draft-ietf-dhc-dhcpv6-21.txt   draft-ietf-dhc-dhcpv6-22.txt 
Internet Engineering Task Force J. Bound Internet Engineering Task Force J. Bound
INTERNET DRAFT Compaq INTERNET DRAFT Compaq
DHC Working Group M. Carney DHC Working Group M. Carney
Obsoletes: draft-ietf-dhc-dhcpv6-20.txt Sun Microsystems, Inc Obsoletes: draft-ietf-dhc-dhcpv6-21.txt Sun Microsystems, Inc
C. Perkins C. Perkins
Nokia Research Center Nokia Research Center
R. Droms(ed.) R. Droms(ed.)
Cisco Systems Cisco Systems
21 Nov 2001 21 Dec 2001
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
draft-ietf-dhc-dhcpv6-21.txt draft-ietf-dhc-dhcpv6-22.txt
Status of This Memo Status of This Memo
This document is a submission by the Dynamic Host Configuration This document is a submission by the Dynamic Host Configuration
Working Group of the Internet Engineering Task Force (IETF). Comments Working Group of the Internet Engineering Task Force (IETF). Comments
should be submitted to the dhcwg@ietf.org mailing list. should be submitted to the dhcwg@ietf.org mailing list.
Distribution of this memo is unlimited. Distribution of this memo is unlimited.
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
skipping to change at page 1, line 47 skipping to change at page 1, line 47
The list of Internet-Draft Shadow Directories can be accessed at: The list of Internet-Draft Shadow Directories can be accessed at:
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
The Dynamic Host Configuration Protocol for IPv6 (DHCP) enables The Dynamic Host Configuration Protocol for IPv6 (DHCP) enables
DHCP servers to pass configuration parameters such as IPv6 network DHCP servers to pass configuration parameters such as IPv6 network
addresses to IPv6 nodes. It offers the capability of automatic addresses to IPv6 nodes. It offers the capability of automatic
allocation of reusable network addresses and additional configuration allocation of reusable network addresses and additional configuration
flexibility. This protocol is a stateful counterpart to "IPv6 flexibility. This protocol is a stateful counterpart to "IPv6
Stateless Address Autoconfiguration" [20], and can be used separately Stateless Address Autoconfiguration" [23], and can be used separately
or concurrently with the latter to obtain configuration parameters. or concurrently with the latter to obtain configuration parameters.
Contents Contents
Status of This Memo i Status of This Memo i
Abstract i Abstract i
1. Introduction 1 1. Introduction 1
2. Requirements 2 2. Requirements 2
3. Background 2 3. Background 2
4. Design Goals 3 4. Design Goals 3
5. Non-Goals 3 5. Non-Goals 4
6. Terminology 4 6. Terminology 4
6.1. IPv6 Terminology . . . . . . . . . . . . . . . . . . . . 4 6.1. IPv6 Terminology . . . . . . . . . . . . . . . . . . . . 4
6.2. DHCP Terminology . . . . . . . . . . . . . . . . . . . . 5 6.2. DHCP Terminology . . . . . . . . . . . . . . . . . . . . 5
7. DHCP Constants 6 7. DHCP Constants 7
7.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 7 7.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 7
7.2. UDP ports . . . . . . . . . . . . . . . . . . . . . . . . 7 7.2. UDP ports . . . . . . . . . . . . . . . . . . . . . . . . 7
7.3. DHCP message types . . . . . . . . . . . . . . . . . . . 7 7.3. DHCP message types . . . . . . . . . . . . . . . . . . . 8
7.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 9 7.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 9
7.4.1. Generic Status Codes . . . . . . . . . . . . . . 9 7.4.1. Generic Status Codes . . . . . . . . . . . . . . 9
7.4.2. Server-specific Status Codes . . . . . . . . . . 9 7.4.2. Server-specific Status Codes . . . . . . . . . . 11
7.5. Configuration Variables . . . . . . . . . . . . . . . . . 10 7.5. Configuration Variables . . . . . . . . . . . . . . . . . 11
8. Message Formats 10 8. Message Formats 12
8.1. DHCP Solicit Message Format . . . . . . . . . . . . . . . 11 8.1. DHCP Solicit Message Format . . . . . . . . . . . . . . . 12
8.2. DHCP Advertise Message Format . . . . . . . . . . . . . . 11 8.2. DHCP Advertise Message Format . . . . . . . . . . . . . . 12
8.3. DHCP Request Message Format . . . . . . . . . . . . . . . 12 8.3. DHCP Request Message Format . . . . . . . . . . . . . . . 13
8.4. DHCP Confirm Message Format . . . . . . . . . . . . . . . 12 8.4. DHCP Confirm Message Format . . . . . . . . . . . . . . . 13
8.5. DHCP Renew Message Format . . . . . . . . . . . . . . . . 12 8.5. DHCP Renew Message Format . . . . . . . . . . . . . . . . 13
8.6. DHCP Rebind Message Format . . . . . . . . . . . . . . . 12 8.6. DHCP Rebind Message Format . . . . . . . . . . . . . . . 14
8.7. DHCP Reply Message Format . . . . . . . . . . . . . . . . 13 8.7. DHCP Reply Message Format . . . . . . . . . . . . . . . . 14
8.8. DHCP Release Message Format . . . . . . . . . . . . . . . 13 8.8. DHCP Release Message Format . . . . . . . . . . . . . . . 14
8.9. DHCP Decline Message Format . . . . . . . . . . . . . . . 13 8.9. DHCP Decline Message Format . . . . . . . . . . . . . . . 14
8.10. DHCP Reconfigure-init Message Format . . . . . . . . . . 13 8.10. DHCP Reconfigure Message Format . . . . . . . . . . . . . 15
8.11. Inform Message Format . . . . . . . . . . . . . . . . . . 14 8.11. Information-Request Message Format . . . . . . . . . . . 15
9. Relay messages 14 9. Relay messages 16
9.1. Relay-forward message . . . . . . . . . . . . . . . . . . 14 9.1. Relay-forward message . . . . . . . . . . . . . . . . . . 16
9.2. Relay-reply message . . . . . . . . . . . . . . . . . . . 15 9.2. Relay-reply message . . . . . . . . . . . . . . . . . . . 17
10. DHCP unique identifier (DUID) 15 10. Representation and use of domain names 17
10.1. DUID contents . . . . . . . . . . . . . . . . . . . . . . 16
10.2. DUID based on link-layer address plus time . . . . . . . 16
10.3. Vendor-assigned unique ID. . . . . . . . . . . . . . . . 17
10.4. Link-layer address . . . . . . . . . . . . . . . . . . . 18
11. Identity association 18 11. DHCP unique identifier (DUID) 17
11.1. DUID contents . . . . . . . . . . . . . . . . . . . . . . 18
11.2. DUID based on link-layer address plus time . . . . . . . 18
11.3. Vendor-assigned unique ID . . . . . . . . . . . . . . . . 19
11.4. Link-layer address . . . . . . . . . . . . . . . . . . . 20
12. Selecting addresses for assignment to an IA 19 12. Identity association 20
13. Reliability of Client Initiated Message Exchanges 19 13. Selecting addresses for assignment to an IA 21
14. Message validation 21 14. Management of temporary addresses 22
14.1. Use of Transaction-ID field . . . . . . . . . . . . . . . 21
14.2. Solicit message . . . . . . . . . . . . . . . . . . . . . 21
14.3. Advertise message . . . . . . . . . . . . . . . . . . . . 21
14.4. Request message . . . . . . . . . . . . . . . . . . . . . 22
14.5. Confirm message . . . . . . . . . . . . . . . . . . . . . 22
14.6. Renew message . . . . . . . . . . . . . . . . . . . . . . 22
14.7. Rebind message . . . . . . . . . . . . . . . . . . . . . 22
14.8. Decline messages . . . . . . . . . . . . . . . . . . . . 22
14.9. Release message . . . . . . . . . . . . . . . . . . . . . 23
14.10. Reply message . . . . . . . . . . . . . . . . . . . . . . 23
14.11. Reconfigure-init message . . . . . . . . . . . . . . . . 23
14.12. Inform message . . . . . . . . . . . . . . . . . . . . . 23
14.13. Relay-forward message . . . . . . . . . . . . . . . . . . 23
14.14. Relay-reply message . . . . . . . . . . . . . . . . . . . 23
15. DHCP Server Solicitation 24 15. Reliability of Client Initiated Message Exchanges 23
15.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 24
15.1.1. Creation of Solicit messages . . . . . . . . . . 24
15.1.2. Transmission of Solicit Messages . . . . . . . . 24
15.1.3. Receipt of Advertise messages . . . . . . . . . . 25
15.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 26
15.2.1. Receipt of Solicit messages . . . . . . . . . . . 26
15.2.2. Creation and transmission of Advertise messages . 26
16. DHCP Client-Initiated Configuration Exchange 27 16. Message validation 24
16.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 27 16.1. Use of Transaction-ID field . . . . . . . . . . . . . . . 25
16.1.1. Creation and transmission of Request messages . . 28 16.2. Solicit message . . . . . . . . . . . . . . . . . . . . . 25
16.1.2. Creation and transmission of Confirm messages . . 29 16.3. Advertise message . . . . . . . . . . . . . . . . . . . . 25
16.1.3. Creation and transmission of Renew messages . . . 30 16.4. Request message . . . . . . . . . . . . . . . . . . . . . 25
16.1.4. Creation and transmission of Rebind messages . . 31 16.5. Confirm message . . . . . . . . . . . . . . . . . . . . . 25
16.1.5. Creation and Transmission of Inform messages . . 33 16.6. Renew message . . . . . . . . . . . . . . . . . . . . . . 26
16.1.6. Receipt of Reply message in response to a Request, 16.7. Rebind message . . . . . . . . . . . . . . . . . . . . . 26
Confirm, Renew, Rebind or Inform message . 33 16.8. Decline messages . . . . . . . . . . . . . . . . . . . . 26
16.1.7. Creation and transmission of Release messages . . 35 16.9. Release message . . . . . . . . . . . . . . . . . . . . . 26
16.1.8. Receipt of Reply message in response to a Release 16.10. Reply message . . . . . . . . . . . . . . . . . . . . . . 26
message . . . . . . . . . . . . . . . . . 36 16.11. Reconfigure message . . . . . . . . . . . . . . . . . . . 27
16.1.9. Creation and transmission of Decline messages . . 36 16.12. Inform message . . . . . . . . . . . . . . . . . . . . . 27
16.1.10. Receipt of Reply message in response to a Decline 16.13. Relay-forward message . . . . . . . . . . . . . . . . . . 27
message . . . . . . . . . . . . . . . . . 37 16.14. Relay-reply message . . . . . . . . . . . . . . . . . . . 27
16.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 38
16.2.1. Receipt of Request messages . . . . . . . . . . . 38
16.2.2. Receipt of Confirm messages . . . . . . . . . . . 39
16.2.3. Receipt of Renew messages . . . . . . . . . . . . 39
16.2.4. Receipt of Rebind messages . . . . . . . . . . . 40
16.2.5. Receipt of Inform messages . . . . . . . . . . . 41
16.2.6. Receipt of Release messages . . . . . . . . . . . 42
16.2.7. Receipt of Decline messages . . . . . . . . . . . 42
16.2.8. Receipt of Decline messages . . . . . . . . . . . 43
16.2.9. Sending of Reply messages . . . . . . . . . . . . 43
17. DHCP Server-Initiated Configuration Exchange 43 17. DHCP Server Solicitation 27
17.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 43 17.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 27
17.1.1. Creation and transmission of Reconfigure-init 17.1.1. Creation of Solicit messages . . . . . . . . . . 28
messages . . . . . . . . . . . . . . . . . 43 17.1.2. Transmission of Solicit Messages . . . . . . . . 28
17.1.2. Time out and retransmission of Reconfigure-init 17.1.3. Receipt of Advertise messages . . . . . . . . . . 29
messages . . . . . . . . . . . . . . . . . 44 17.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 30
17.1.3. Receipt of Rebind messages . . . . . . . . . . . 44 17.2.1. Receipt of Solicit messages . . . . . . . . . . . 30
17.2. Client Behavior . . . . . . . . . . . . . . . . . . . . . 45 17.2.2. Creation and transmission of Advertise messages . 30
17.2.1. Receipt of Reconfigure-init messages . . . . . . 45
17.2.2. Creation and sending of Rebind messages . . . . . 46
17.2.3. Time out and retransmission of Rebind messages . 46
17.2.4. Receipt of Reply messages . . . . . . . . . . . . 46
18. Relay Behavior 46 18. DHCP Client-Initiated Configuration Exchange 31
18.1. Relaying of client messages . . . . . . . . . . . . . . . 46 18.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 31
18.2. Relaying of server messages . . . . . . . . . . . . . . . 47 18.1.1. Creation and transmission of Request messages . . 31
18.1.2. Creation and transmission of Confirm messages . . 33
18.1.3. Creation and transmission of Renew messages . . . 34
18.1.4. Creation and transmission of Rebind messages . . 35
18.1.5. Creation and Transmission of Inform messages . . 36
18.1.6. Receipt of Reply message in response to a Request,
Confirm, Renew, Rebind or Inform message . 37
18.1.7. Creation and transmission of Release messages . . 39
18.1.8. Receipt of Reply message in response to a Release
message . . . . . . . . . . . . . . . . . 40
18.1.9. Creation and transmission of Decline messages . . 40
18.1.10. Receipt of Reply message in response to a Decline
message . . . . . . . . . . . . . . . . . 41
18.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 41
18.2.1. Receipt of Request messages . . . . . . . . . . . 41
18.2.2. Receipt of Confirm messages . . . . . . . . . . . 42
18.2.3. Receipt of Renew messages . . . . . . . . . . . . 43
18.2.4. Receipt of Rebind messages . . . . . . . . . . . 44
18.2.5. Receipt of Inform messages . . . . . . . . . . . 45
18.2.6. Receipt of Release messages . . . . . . . . . . . 45
18.2.7. Receipt of Decline messages . . . . . . . . . . . 46
18.2.8. Receipt of Information-Request messages . . . . . 46
18.2.9. Sending of Reply messages . . . . . . . . . . . . 46
19. Authentication of DHCP messages 47 19. DHCP Server-Initiated Configuration Exchange 47
19.1. DHCP threat model . . . . . . . . . . . . . . . . . . . . 48 19.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 47
19.2. Security of messages sent between servers and relay agents 48 19.1.1. Creation and transmission of Reconfigure messages 47
19.3. Summary of DHCP authentication . . . . . . . . . . . . . 48 19.1.2. Time out and retransmission of Reconfigure
19.4. Replay detection . . . . . . . . . . . . . . . . . . . . 49 messages . . . . . . . . . . . . . . . . . 48
19.5. Configuration token protocol . . . . . . . . . . . . . . 49 19.1.3. Receipt of Renew messages . . . . . . . . . . . . 48
19.6. Delayed authentication protocol . . . . . . . . . . . . . 49 19.2. Receipt of Information-request messages . . . . . . . . . 48
19.6.1. Management issues in the delayed authentication 19.3. Client Behavior . . . . . . . . . . . . . . . . . . . . . 49
protocol . . . . . . . . . . . . . . . . . 50 19.3.1. Receipt of Reconfigure messages . . . . . . . . . 49
19.6.2. Use of the Authentication option in the delayed 19.3.2. Creation and sending of Renew messages . . . . . 50
authentication protocol . . . . . . . . . 50 19.3.3. Creation and sending of Renew messages . . . . . 50
19.6.3. Message validation . . . . . . . . . . . . . . . 51 19.3.4. Time out and retransmission of Renew or
19.6.4. Key utilization . . . . . . . . . . . . . . . . . 51 Information-request messages . . . . . . . 50
19.6.5. Client considerations for delayed authentication 19.3.5. Receipt of Reply messages . . . . . . . . . . . . 50
protocol . . . . . . . . . . . . . . . . . 52
19.6.6. Server considerations for delayed authentication
protocol . . . . . . . . . . . . . . . . . 53
20. DHCP options 54 20. Relay Behavior 50
20.1. Format of DHCP options . . . . . . . . . . . . . . . . . 54 20.1. Relaying of client messages . . . . . . . . . . . . . . . 50
20.2. DHCP unique identifier option . . . . . . . . . . . . . . 54 20.2. Relaying of server messages . . . . . . . . . . . . . . . 51
20.3. Identity association option . . . . . . . . . . . . . . . 55
20.4. IA Address option . . . . . . . . . . . . . . . . . . . . 56
20.5. Option request option . . . . . . . . . . . . . . . . . . 57
20.6. Preference option . . . . . . . . . . . . . . . . . . . . 58
20.7. Elapsed Time . . . . . . . . . . . . . . . . . . . . . . 58
20.8. Client message option . . . . . . . . . . . . . . . . . . 58
20.9. Server message option . . . . . . . . . . . . . . . . . . 59
20.10. DSTM Global IPv4 Address Option . . . . . . . . . . . . . 59
20.11. Authentication option . . . . . . . . . . . . . . . . . . 60
20.12. Server unicast option . . . . . . . . . . . . . . . . . . 61
20.13. Domain Search Option . . . . . . . . . . . . . . . . . . 61
20.14. Domain Name Server Option . . . . . . . . . . . . . . . . 62
20.15. Status Code Option . . . . . . . . . . . . . . . . . . . 63
20.16. Circuit-ID Option . . . . . . . . . . . . . . . . . . . . 63
20.17. User Class Option . . . . . . . . . . . . . . . . . . . . 64
20.18. Vendor Class Option . . . . . . . . . . . . . . . . . . . 65
21. Security Considerations 66 21. Authentication of DHCP messages 51
21.1. DHCP threat model . . . . . . . . . . . . . . . . . . . . 52
21.2. Security of messages sent between servers and relay agents 52
21.3. Summary of DHCP authentication . . . . . . . . . . . . . 52
21.4. Replay detection . . . . . . . . . . . . . . . . . . . . 53
21.5. Configuration token protocol . . . . . . . . . . . . . . 53
21.6. Delayed authentication protocol . . . . . . . . . . . . . 54
21.6.1. Management issues in the delayed authentication
protocol . . . . . . . . . . . . . . . . . 54
21.6.2. Use of the Authentication option in the delayed
authentication protocol . . . . . . . . . 54
21.6.3. Message validation . . . . . . . . . . . . . . . 55
21.6.4. Key utilization . . . . . . . . . . . . . . . . . 55
21.6.5. Client considerations for delayed authentication
protocol . . . . . . . . . . . . . . . . . 56
21.6.6. Server considerations for delayed authentication
protocol . . . . . . . . . . . . . . . . . 58
22. Year 2000 considerations 66 22. DHCP options 58
22.1. Format of DHCP options . . . . . . . . . . . . . . . . . 59
22.2. DHCP unique identifier option . . . . . . . . . . . . . . 59
22.3. Identity association option . . . . . . . . . . . . . . . 60
22.4. IA Address option . . . . . . . . . . . . . . . . . . . . 62
22.5. Requested Temporary Addresses (RTA) Option . . . . . . . 63
22.6. Option request option . . . . . . . . . . . . . . . . . . 64
22.7. Preference option . . . . . . . . . . . . . . . . . . . . 64
22.8. Elapsed Time . . . . . . . . . . . . . . . . . . . . . . 65
22.9. Client message option . . . . . . . . . . . . . . . . . . 65
22.10. Server message option . . . . . . . . . . . . . . . . . . 66
22.11. DSTM Global IPv4 Address Option . . . . . . . . . . . . . 66
22.12. DSTM Tunnel EndPoint Option . . . . . . . . . . . . . . 67
22.13. Authentication option . . . . . . . . . . . . . . . . . . 67
22.14. Server unicast option . . . . . . . . . . . . . . . . . . 68
22.15. Domain Search Option . . . . . . . . . . . . . . . . . . 69
22.16. Domain Name Server Option . . . . . . . . . . . . . . . . 70
22.17. Status Code Option . . . . . . . . . . . . . . . . . . . 70
22.18. Circuit-ID Option . . . . . . . . . . . . . . . . . . . . 71
22.19. User Class Option . . . . . . . . . . . . . . . . . . . . 72
22.20. Vendor Class Option . . . . . . . . . . . . . . . . . . . 72
22.21. SIP Servers Domain Name List . . . . . . . . . . . . . . 74
22.22. SIP Servers IPv6 Address List . . . . . . . . . . . . . . 74
23. IANA Considerations 66 23. Security Considerations 75
23.1. Multicast addresses . . . . . . . . . . . . . . . . . . . 66
23.2. DHCPv6 message types . . . . . . . . . . . . . . . . . . 66
23.3. DUID . . . . . . . . . . . . . . . . . . . . . . . . . . 67
23.4. DHCPv6 options . . . . . . . . . . . . . . . . . . . . . 67
23.5. Status codes . . . . . . . . . . . . . . . . . . . . . . 67
23.6. Authentication option . . . . . . . . . . . . . . . . . . 67
24. Acknowledgments 67 24. Year 2000 considerations 75
A. Full Copyright Statement 68 25. IANA Considerations 75
25.1. Multicast addresses . . . . . . . . . . . . . . . . . . . 75
25.2. DHCPv6 message types . . . . . . . . . . . . . . . . . . 75
25.3. DUID . . . . . . . . . . . . . . . . . . . . . . . . . . 76
25.4. DHCPv6 options . . . . . . . . . . . . . . . . . . . . . 76
25.5. Status codes . . . . . . . . . . . . . . . . . . . . . . 76
25.6. Authentication option . . . . . . . . . . . . . . . . . . 76
References 68 26. Acknowledgments 76
Chair's Address 70 A. Full Copyright Statement 77
Authors' Addresses 70 B. Appearance of Options in Message Types 78
C. Appearance of Options in the Options Field of DHCP Messages 79
References 79
Chair's Address 81
Authors' Addresses 82
1. Introduction 1. Introduction
This document describes DHCP for IPv6 (DHCP), a UDP [18] This document describes DHCP for IPv6 (DHCP), a UDP [20]
client/server protocol designed to reduce the cost of management client/server protocol designed to reduce the cost of management
of IPv6 nodes in environments where network managers require more of IPv6 nodes in environments where network managers require more
control over the allocation of IPv6 addresses and configuration control over the allocation of IPv6 addresses and configuration
of network stack parameters than that offered by "IPv6 Stateless of network stack parameters than that offered by "IPv6 Stateless
Address Autoconfiguration" [20]. DHCP is a stateful counterpart to Address Autoconfiguration" [23]. DHCP is a stateful counterpart to
stateless autoconfiguration. Note that both stateful and stateless stateless autoconfiguration. Note that both stateful and stateless
autoconfiguration can be used concurrently in the same environment, autoconfiguration can be used concurrently in the same environment,
leveraging the strengths of both mechanisms in order to reduce the leveraging the strengths of both mechanisms in order to reduce the
cost of ownership and management of network nodes. cost of ownership and management of network nodes.
DHCP reduces the cost of ownership by centralizing the management DHCP reduces the cost of ownership by centralizing the management
of network resources such as IP addresses, routing information, OS of network resources such as IP addresses, routing information, OS
installation information, directory service information, and other installation information, directory service information, and other
such information on a few DHCP servers, rather than distributing such such information on a few DHCP servers, rather than distributing such
information in local configuration files among each network node. information in local configuration files among all network node.
DHCP is designed to be easily extended to carry new configuration DHCP is designed to be easily extended to carry new configuration
parameters through the addition of new DHCP "options" defined to parameters through the addition of new DHCP "options" defined to
carry this information. carry this information.
Those readers familiar with DHCP for IPv4 [7] will findDHCP for IPv6 Those readers familiar with DHCP for IPv4 [8] will find DHCP for
provides a superset of features, and benefits from the additional IPv6 provides a superset of the features of DHCP and benefits from
features of IPv6 and freedom from the constraints of backward the additional features of IPv6 and freedom from the constraints of
compatibility with BOOTP [5]. backward compatibility with BOOTP [6].
2. Requirements 2. Requirements
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [3]. document, are to be interpreted as described in [4].
This document also makes use of internal conceptual variables This document also makes use of internal conceptual variables
to describe protocol behavior and external variables that an to describe protocol behavior and external variables that an
implementation must allow system administrators to change. The implementation must allow system administrators to change. The
specific variable names, how their values change, and how their specific variable names, how their values change, and how their
settings influence protocol behavior are provided to demonstrate settings influence protocol behavior are provided to demonstrate
protocol behavior. An implementation is not required to have them in protocol behavior. An implementation is not required to have them in
the exact form described here, so long as its external behavior is the exact form described here, so long as its external behavior is
consistent with that described in this document. consistent with that described in this document.
3. Background 3. Background
The IPv6 Specification provides the base architecture and design of The IPv6 Specification provides the base architecture and design of
IPv6. Related work in IPv6 that would best serve an implementor IPv6. Related work in IPv6 that would best serve an implementor
to study is the IPv6 Specification [6], the IPv6 Addressing to study includes the IPv6 Specification [7], the IPv6 Addressing
Architecture [9], IPv6 Stateless Address Autoconfiguration [20], IPv6 Architecture [10], IPv6 Stateless Address Autoconfiguration [23],
Neighbor Discovery Processing [16], and Dynamic Updates to DNS [21]. IPv6 Neighbor Discovery Processing [18], and Dynamic Updates to
These specifications enable DHCP to build upon the IPv6 work to DNS [24]. These specifications enable DHCP to build upon the
provide both robust stateful autoconfiguration and autoregistration IPv6 work to provide both robust stateful autoconfiguration and
of DNS Host Names. autoregistration of DNS Host Names.
The IPv6 Addressing Architecture specification [9] defines the The IPv6 Addressing Architecture specification [10] defines the
address scope that can be used in an IPv6 implementation, and the address scope that can be used in an IPv6 implementation, and the
various configuration architecture guidelines for network designers various configuration architecture guidelines for network designers
of the IPv6 address space. Two advantages of IPv6 are that support of the IPv6 address space. Two advantages of IPv6 are that support
for multicast is required, and nodes can create link-local addresses for multicast is required, and nodes can create link-local addresses
during initialization. This means that a client can immediately use during initialization. This means that a client can immediately use
its link-local address and a well-known multicast address to begin its link-local address and a well-known multicast address to begin
communications to discover neighbors on the link. For instance, a communications to discover neighbors on the link. For instance, a
client can send a Solicit message and locate a server or relay. client can send a Solicit message and locate a server or relay.
IPv6 Stateless Address Autoconfiguration [20] specifies procedures IPv6 Stateless Address Autoconfiguration [23] specifies procedures
by which a node may autoconfigure addresses based on router by which a node may autoconfigure addresses based on router
advertisements [16], and the use of a valid lifetime to support advertisements [18], and the use of a valid lifetime to support
renumbering of addresses on the Internet. In addition the renumbering of addresses on the Internet. In addition the
protocol interaction by which a node begins stateless or stateful protocol interaction by which a node begins stateless or stateful
autoconfiguration is specified. DHCP is one vehicle to perform autoconfiguration is specified. DHCP is one vehicle to perform
stateful autoconfiguration. Compatibility with stateless address stateful autoconfiguration. Compatibility with stateless address
autoconfiguration is a design requirement of DHCP (see Section 4). autoconfiguration is a design requirement of DHCP (see Section 4).
IPv6 Neighbor Discovery [16] is the node discovery protocol in IPv6 IPv6 Neighbor Discovery [18] is the node discovery protocol in IPv6
which replaces and enhances functions of ARP [17]. To understand which replaces and enhances functions of ARP [19]. To understand
IPv6 and stateless address autoconfiguration it is strongly IPv6 and stateless address autoconfiguration it is strongly
recommended that implementors understand IPv6 Neighbor Discovery. recommended that implementors understand IPv6 Neighbor Discovery.
Dynamic Updates to DNS [21] is a specification that supports the Dynamic Updates to DNS [24] is a specification that supports the
dynamic update of DNS records for both IPv4 and IPv6. DHCP can use dynamic update of DNS records for both IPv4 and IPv6. DHCP can use
the dynamic updates to DNS to integrate addresses and name space to the dynamic updates to DNS to integrate addresses and name space to
not only support autoconfiguration, but also autoregistration in not only support autoconfiguration, but also autoregistration in
IPv6. IPv6.
4. Design Goals 4. Design Goals
- DHCP is a mechanism rather than a policy. Network administrators - DHCP is a mechanism rather than a policy. Network administrators
set their administrative policies through the configuration set their administrative policies through the configuration
parameters they place upon the DHCP servers in the DHCP domain parameters they place upon the DHCP servers in the DHCP domain
they're managing. DHCP is simply used to deliver parameters they're managing. DHCP is simply used to deliver parameters
according to that policy to each of the DHCP clients within the according to that policy to each of the DHCP clients within the
domain. domain.
- DHCP is compatible with IPv6 stateless address - DHCP is compatible with IPv6 stateless address
autoconfiguration [20], statically configured, non-participating autoconfiguration [23], statically configured, non-participating
nodes and with existing network protocol implementations. nodes and with existing network protocol implementations.
- DHCP does not require manual configuration of network parameters - DHCP does not require manual configuration of network parameters
on DHCP clients, except in cases where such configuration is on DHCP clients, except in cases where such configuration is
needed for security reasons. A node configuring itself using needed for security reasons. A node configuring itself using
DHCP should require no user intervention. DHCP should require no user intervention.
- DHCP does not require a server on each link. To allow for scale - DHCP does not require a server on each link. To allow for scale
and economy, DHCP must work across DHCP relays. and economy, DHCP must work across DHCP relays.
- DHCP clients can operate on a link without IPv6 routers present. - DHCP clients can operate on a link without IPv6 routers present.
- DHCP will provide the ability to renumber network(s) when - DHCP will provide the ability to renumber network(s) when
required by network administrators [4]. required by network administrators [5].
- A DHCP client can make multiple, different requests for - A DHCP client can make multiple, different requests for
configuration parameters when necessary from one or more DHCP configuration parameters when necessary from one or more DHCP
servers at any time. servers at any time.
- DHCP will contain the appropriate time out and retransmission - DHCP will contain the appropriate time out and retransmission
mechanisms to efficiently operate in environments with high mechanisms to efficiently operate in environments with high
latency and low bandwidth characteristics. latency and low bandwidth characteristics.
5. Non-Goals 5. Non-Goals
skipping to change at page 4, line 18 skipping to change at page 4, line 30
log. log.
6. Terminology 6. Terminology
This sections defines terminology specific to IPv6 and DHCP used in This sections defines terminology specific to IPv6 and DHCP used in
this document. this document.
6.1. IPv6 Terminology 6.1. IPv6 Terminology
IPv6 terminology relevant to this specification from the IPv6 IPv6 terminology relevant to this specification from the IPv6
Protocol [6], IPv6 Addressing Architecture [9], and IPv6 Stateless Protocol [7], IPv6 Addressing Architecture [10], and IPv6 Stateless
Address Autoconfiguration [20] is included below. Address Autoconfiguration [23] is included below.
address An IP layer identifier for an interface or address An IP layer identifier for an interface
a set of interfaces. or a set of interfaces.
unicast address An identifier for a single interface. unicast address An identifier for a single interface.
A packet sent to a unicast address is A packet sent to a unicast address is
delivered to the interface identified by delivered to the interface identified by
that address. that address.
multicast address An identifier for a set of interfaces multicast address An identifier for a set of interfaces
(typically belonging to different nodes). (typically belonging to different
A packet sent to a multicast address is nodes). A packet sent to a multicast
delivered to all interfaces identified by address is delivered to all interfaces
that address. identified by that address.
host Any node that is not a router. host Any node that is not a router.
IP Internet Protocol Version 6 (IPv6). The IP Internet Protocol Version 6 (IPv6). The
terms IPv4 and IPv6 are used only in terms IPv4 and IPv6 are used only in
contexts where it is necessary to avoid contexts where it is necessary to avoid
ambiguity. ambiguity.
interface A node's attachment to a link. interface A node's attachment to a link.
link A communication facility or medium over link A communication facility or medium over
which nodes can communicate at the link which nodes can communicate at the link
layer, i.e., the layer immediately below layer, i.e., the layer immediately below
IP. Examples are Ethernet (simple or IP. Examples are Ethernet (simple or
bridged); Token Ring; PPP links, X.25, bridged); Token Ring; PPP links, X.25,
Frame Relay, or ATM networks; and Internet
(or higher) layer "tunnels", such as
tunnels over IPv4 or IPv6 itself.
link-layer identifier A link-layer identifier for an interface. Frame Relay, or ATM networks; and
Examples include IEEE 802 addresses for Internet (or higher) layer "tunnels",
Ethernet or Token Ring network interfaces, such as tunnels over IPv4 or IPv6
and E.164 addresses for ISDN links. itself.
link-layer identifier A link-layer identifier for an
interface. Examples include IEEE 802
addresses for Ethernet or Token Ring
network interfaces, and E.164 addresses
for ISDN links.
link-local address An IPv6 address having link-only link-local address An IPv6 address having link-only
scope, indicated by having the prefix scope, indicated by having the prefix
(FE80::0000/64), that can be used to reach (FE80::0000/64), that can be used to
neighboring nodes attached to the same reach neighboring nodes attached to
link. Every interface has a link-local the same link. Every interface has a
address. link-local address.
message A unit of data carried in a packet,
exchanged between DHCP agents and clients.
neighbor A node attached to the same link. neighbor A node attached to the same link.
node A device that implements IP. node A device that implements IP.
packet An IP header plus payload. packet An IP header plus payload.
prefix The initial bits of an address, or a set prefix The initial bits of an address, or a
of IP address that share the same initial set of IP address that share the same
bits. initial bits.
prefix length The number of bits in a prefix. prefix length The number of bits in a prefix.
router A node that forwards IP packets not router A node that forwards IP packets not
explicitly addressed to itself. explicitly addressed to itself.
6.2. DHCP Terminology 6.2. DHCP Terminology
Terminology specific to DHCP can be found below. Terminology specific to DHCP can be found below.
skipping to change at page 6, line 32 skipping to change at page 6, line 42
client(s). client(s).
DHCP relay (or relay) A node that acts as an intermediary to DHCP relay (or relay) A node that acts as an intermediary to
deliver DHCP messages between clients deliver DHCP messages between clients
and servers, and is on the same link as and servers, and is on the same link as
a client. a client.
DHCP agent (or agent) Either a DHCP server on the same link as DHCP agent (or agent) Either a DHCP server on the same link as
a client, or a DHCP relay. a client, or a DHCP relay.
DUID A DHCP Unique IDentifier for a client. DUID A DHCP Unique IDentifier for a client;
each DHCP client has exactly one DUID
Identity association (IA) A collection of addresses assigned to Identity association (IA) A collection of addresses assigned to
a client. Each IA has an associated a client. Each IA has an associated
IAID. An IA may have 0 or more addresses IAID. An IA may have 0 or more addresses
associated with it. associated with it.
Identity association identifier (IAID) An identifier for an IA, Identity association identifier (IAID) An identifier for an IA,
chosen by the client. Each IA has an chosen by the client. Each IA has an
IAID, which is chosen to be unique among IAID, which is chosen to be unique among
all IAIDs for IAs belonging to that all IAIDs for IAs belonging to that
client. client.
message A unit of data carried in a packet,
exchanged between DHCP agents and
clients.
transaction-ID An unsigned integer to match responses transaction-ID An unsigned integer to match responses
with replies initiated either by a with replies initiated either by a
client or server. client or server.
7. DHCP Constants 7. DHCP Constants
This section describes various program and networking constants used This section describes various program and networking constants used
by DHCP. by DHCP.
7.1. Multicast Addresses 7.1. Multicast Addresses
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with server(s), either because they want to send with server(s), either because they want to send
messages to all servers or because they do not know messages to all servers or because they do not know
the server(s) unicast address(es). Note that in order the server(s) unicast address(es). Note that in order
for a client to use this address, it must have an for a client to use this address, it must have an
address of sufficient scope to be reachable by the address of sufficient scope to be reachable by the
server(s). All servers within the site are members of server(s). All servers within the site are members of
this multicast group. this multicast group.
7.2. UDP ports 7.2. UDP ports
DHCP uses the following destination UDP [18] port numbers. While DHCP uses the following destination UDP [20] port numbers. While
source ports MAY be arbitrary, client implementations SHOULD permit source ports MAY be arbitrary, client implementations SHOULD permit
their specification through a local configuration parameter to their specification through a local configuration parameter to
facilitate the use of DHCP through firewalls. facilitate the use of DHCP through firewalls.
546 Client port. Used by servers as the destination port 546 Client port. Used by servers as the destination port
for messages sent to clients and relays. Used by relay for messages sent to clients and relays. Used by relay
agents as the destination port for messages sent to agents as the destination port for messages sent to
clients. clients.
547 Agent port. Used as the destination port by clients 547 Agent port. Used as the destination port by clients
for messages sent to agents. Used as the destination for messages sent to agents. Used as the destination
port by relays for messages sent to servers. port by relays for messages sent to servers.
7.3. DHCP message types 7.3. DHCP message types
DHCP defines the following message types. More detail on these DHCP defines the following message types. More detail on these
message types can be found in Section 8. Message types 0 and 13-255 message types can be found in Section 8. Message types not listed
are reserved for future use. The message code for each message type here are reserved for future use. The message code for each message
is shown with the message name. type is shown with the message name.
SOLICIT (1) The Solicit message is used by clients to SOLICIT (1) The Solicit message is used by clients to
locate servers. locate servers.
ADVERTISE (2) The Advertise message is used by servers ADVERTISE (2) The Advertise message is used by servers
responding to Solicits. responding to Solicits.
REQUEST (3) The Request message is used by clients REQUEST (3) The Request message is used by clients to
to request configuration parameters from request configuration parameters from servers.
servers.
CONFIRM (4) The Confirm message is used by clients to CONFIRM (4) The Confirm message is used by clients to
confirm that the addresses assigned to an IA confirm that the addresses assigned to an IA
and the lifetimes for those addresses, as and the lifetimes for those addresses, as
well as the current configuration parameters well as the current configuration parameters
assigned by the server to the client are assigned by the server to the client are still
still valid. valid.
RENEW (5) The Renew message is used by clients to RENEW (5) The Renew message is used by clients to
update the addresses assigned to an IA and update the addresses assigned to an IA and the
the lifetimes for those addresses, as well as lifetimes for those addresses, as well as the
the current configuration parameters assigned current configuration parameters assigned by
by the server to the client. A client sends the server to the client. A client sends a
a Renew message to the server that originally Renew message to the server that originally
populated the IA at time T1. populated the IA at time T1.
REBIND (6) The Rebind message is used by clients to REBIND (6) The Rebind message is used by clients to extend
extend the lifetimes of addresses assigned to the lifetimes of addresses assigned to an IA,
an IA, as well as the current configuration as well as the current configuration parameters
parameters assigned by the server to the assigned by the server to the client. A
client. A client sends a Rebind message to client sends a Rebind message to all available
all available DHCP servers at time T2 only DHCP servers at time T2 only after the client
after the client has been unable to contact has been unable to contact the server that
the server that originally populated the IA originally populated the IA with a Renew
with a Rebind message. message.
REPLY (7) The Reply message is used by servers REPLY (7) The Reply message is used by servers responding
responding to Request, Confirm, Renew, to Request, Confirm, Renew, Rebind, Release and
Rebind, Release and Decline messages. In the Decline messages. In the case of responding to
case of responding to a Request, Confirm, a Request, Confirm, Renew or Rebind message,
Renew or Rebind message, the Reply contains the Reply contains configuration parameters
configuration parameters destined for the destined for the client.
client.
RELEASE (8) The Release message is used by clients to RELEASE (8) The Release message is used by clients to
return one or more IP addresses to servers. indicate to a server that the client will no
longer use one or more addresses in an IA.
DECLINE (9) The Decline message is used by clients to DECLINE (9) The Decline message is used by clients to
indicate that the client has determined that indicate that the client has determined that
one or more addresses in an IA are already one or more addresses in an IA are already
in use on the link to which the client is in use on the link to which the client is
connected. connected.
RECONFIG-INIT (10) The Reconfigure-init message is sent by RECONFIGURE (10) The Reconfigure message is sent by server(s)
server(s) to inform client(s) that the to inform client(s) that the server(s) has new
server(s) has new or updated configuration or updated configuration parameters, and that
parameters, and that the client(s) are to the client(s) are to initiate a Request/Reply
initiate a Request/Reply transaction with the transaction with the server(s) in order to
server(s) in order to receive the updated receive the updated information.
information.
INFORM (11) The Inform message is sent by clients to INFORMATION-REQUEST (11) The Information-request message is sent
request configuration parameters without the by clients to request configuration parameters
assignment of any IP addresses to the client. without the assignment of any IP addresses to
the client.
RELAY-FORW (12) The Relay-forward message is used by relays RELAY-FORW (12) The Relay-forward message is used by relays to
to forward client messages to servers. The forward client messages to servers. The client
client message is encapsulated in an option message is encapsulated in an option in the
in the Relay-forward message. Relay-forward message.
RELAY-REPL (13) The Relay-reply message is used by servers RELAY-REPL (13) The Relay-reply message is used by servers to
to send messages to clients through a relay. send messages to clients through a relay. The
The server encapsulates the client message server encapsulates the client message as an
as an option in the Relay-reply message, option in the Relay-reply message, which the
which the relay extracts and forwards to the relay extracts and forwards to the client.
client.
7.4. Status Codes 7.4. Status Codes
This section describes status codes exchanged between DHCP This section describes status codes exchanged between DHCP
implementations. These status codes may appear in the Status Code implementations. These status codes may appear in the Status Code
option or in the status field of an IA. option or in the status field of an IA.
7.4.1. Generic Status Codes 7.4.1. Generic Status Codes
The status codes in this section are used between clients and servers The status codes in this section are used between clients and servers
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The status codes in this section are used by servers to convey status The status codes in this section are used by servers to convey status
conditions to clients. The following table contains the status conditions to clients. The following table contains the status
codes, the name for each code (as used in this document) and a brief codes, the name for each code (as used in this document) and a brief
description. Note that the numeric values do not start at 1, nor are description. Note that the numeric values do not start at 1, nor are
they consecutive. The status codes are organized in logical groups. they consecutive. The status codes are organized in logical groups.
Name Code Description Name Code Description
---- ---- ----------- ---- ---- -----------
NoBinding 32 Client record (binding) unavailable NoBinding 32 Client record (binding) unavailable
ConfNoMatch 33 Client record Confirm not match IA ConfNoMatch 33 Client record Confirm doesn't match IA
RenwNoMatch 34 Client record Renew not match IA RenwNoMatch 34 Client record Renew doesn't match IA
RebdNoMatch 35 Client record Rebind not match IA RebdNoMatch 35 Client record Rebind doesn't match IA
InvalidSource 36 Invalid Client IP address InvalidSource 36 Invalid Client IP address
NoServer 37 Relay cannot find Server Address NoPrefixMatch 37 One or more prefixes of the addresses
NoPrefixMatch 38 One or more prefixes of the addresses
in the IA is not valid for the link in the IA is not valid for the link
from which the client message was received from which the client message was received
ICMPError 64 Server unreachable (ICMP error)
7.5. Configuration Variables 7.5. Configuration Variables
This section presents a table of client and server configuration This section presents a table of client and server configuration
variables and the default or initial values for these variables. variables and the default or initial values for these variables.
Parameter Default Description Parameter Default Description
------------------------------------- -------------------------------------
MIN_SOL_DELAY 1 sec Min delay of first Solicit MIN_SOL_DELAY 1 sec Min delay of first Solicit
MAX_SOL_DELAY 5 secs Max delay of first Solicit MAX_SOL_DELAY 5 secs Max delay of first Solicit
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DEC_TIMEOUT 250 msecs Initial Release timeout DEC_TIMEOUT 250 msecs Initial Release timeout
DEC_MAX_RT 1 sec Max Release timeout DEC_MAX_RT 1 sec Max Release timeout
DEC_MAX_RC 5 MAX Release/Decline attempts DEC_MAX_RC 5 MAX Release/Decline attempts
8. Message Formats 8. Message Formats
All DHCP messages sent between clients and servers share an identical All DHCP messages sent between clients and servers share an identical
fixed format header and a variable format area for options. Not all fixed format header and a variable format area for options. Not all
fields in the header are used in every message. fields in the header are used in every message.
All values in the message header and in options are in network byte All values in the message header and in options are in network order.
order.
The following diagram illustrates the DHCP message header: The following diagram illustrates the format of DHCP messages sent
between clients and servers:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | transaction-ID | | msg-type | transaction-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| server-address | | server-address |
| (16 octets) | | (16 octets) |
| | | |
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unused fields in a message MUST be transmitted as zeroes and ignored unused fields in a message MUST be transmitted as zeroes and ignored
by the receiver of the message. by the receiver of the message.
8.1. DHCP Solicit Message Format 8.1. DHCP Solicit Message Format
msg-type SOLICIT msg-type SOLICIT
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Solicit message. to identify this Solicit message.
server-address (unused) MUST be 0 server-address (Unused) MUST be zero
options See section 20. options See section 22.
8.2. DHCP Advertise Message Format 8.2. DHCP Advertise Message Format
msg-type ADVERTISE msg-type ADVERTISE
transaction-ID An unsigned integer used to identify this transaction-ID An unsigned integer used to identify this
Advertise message. Copied from the Solicit Advertise message. Copied from the Solicit
message received from the client. message received from the client.
server-address The IP address of the server that generated this server-address The IP address of the server that generated this
message. The address must have sufficient scope message. The address must have sufficient scope
to be reachable from the client. to be reachable from the client.
options See section 20. options See section 22.
8.3. DHCP Request Message Format 8.3. DHCP Request Message Format
msg-type REQUEST msg-type REQUEST
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Request message. to identify this Request message.
server-address The IP address of the server to which this server-address The IP address of the server to which this
message is directed, copied from an Advertise message is directed, copied from an Advertise
message. message.
options See section 20. options See section 22.
8.4. DHCP Confirm Message Format 8.4. DHCP Confirm Message Format
msg-type CONFIRM msg-type CONFIRM
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Confirm message. to identify this Confirm message.
server-address MUST be zero. server-address MUST be zero.
options See section 20. options See section 22.
8.5. DHCP Renew Message Format 8.5. DHCP Renew Message Format
msg-type RENEW msg-type RENEW
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Renew message. to identify this Renew message.
server-address The IP address of the server to which this Renew server-address The IP address of the server to which this Renew
message is directed, which MUST be the address message is directed, which MUST be the address
of the server from which the IAs in this message of the server from which the IAs in this message
were originally assigned. were originally assigned.
options See section 20. options See section 22.
8.6. DHCP Rebind Message Format 8.6. DHCP Rebind Message Format
msg-type REBIND msg-type REBIND
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Rebind message. to identify this Rebind message.
server-address MUST be zero. server-address MUST be zero.
options See section 20. options See section 22.
8.7. DHCP Reply Message Format 8.7. DHCP Reply Message Format
msg-type REPLY msg-type REPLY
transaction-ID An unsigned integer used to identify this transaction-ID An unsigned integer used to identify this
Reply message. Copied from the client Request, Reply message. Copied from the client Request,
Confirm, Renew or Rebind message received from Confirm, Renew or Rebind message received from
the client. the client.
server-address The IP address of the server. server-address The IP address of the server.
options See section 20. options See section 22.
8.8. DHCP Release Message Format 8.8. DHCP Release Message Format
msg-type RELEASE msg-type RELEASE
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Release message. to identify this Release message.
server-address The IP address of the server that assigned the server-address The IP address of the server that assigned the
addresses. addresses.
options See section 20. options See section 22.
8.9. DHCP Decline Message Format 8.9. DHCP Decline Message Format
msg-type DECLINE msg-type DECLINE
transaction-ID An unsigned integer generated by the client used transaction-ID An unsigned integer generated by the client used
to identify this Decline message. to identify this Decline message.
server-address The IP address of the server that assigned the server-address The IP address of the server that assigned the
addresses. addresses.
options See section 20. options See section 22.
8.10. DHCP Reconfigure-init Message Format 8.10. DHCP Reconfigure Message Format
msg-type RECONFIG-INIT msg-type RECONFIG
transaction-ID An unsigned integer generated by the server used transaction-ID An unsigned integer generated by the server used
to identify this Reconfigure-init message. to identify this Reconfigure message.
server-address The IP address of the DHCP server issuing the server-address The IP address of the DHCP server issuing the
Reconfigure-init message. The address must have Reconfigure message. The address must have
sufficient scope to be reachable from the client. sufficient scope to be reachable from the client.
options See section 20. options See section 22.
8.11. DHCP Inform Message Format 8.11. Information-Request Message Format
msg-type INFORM msg-type INFORM
transaction-ID An unsigned integer generated by the server used transaction-ID An unsigned integer generated by the client used
to identify this Inform message. to identify this Inform message.
server-address MUST be zero. server-address Contains IP address of server to which this
message is directed, or 0 if any server may
respond.
options See section 20. options See section 22.
9. Relay messages 9. Relay messages
Relay agents exchange messages with servers to forward messages Relay agents exchange messages with servers to forward messages
between clients and servers that are not connected to the same link. between clients and servers that are not connected to the same link.
There are two relay messages, which share the following format: There are two relay messages, which share the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 15, line 4 skipping to change at page 16, line 41
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following sections describe the use of the Relay message header. The following sections describe the use of the Relay message header.
9.1. Relay-forward message 9.1. Relay-forward message
The following table defines the use of message fields in a The following table defines the use of message fields in a
Relay-forward message. Relay-forward message.
msg-type RELAY-FORW msg-type RELAY-FORW
link-address An address with a prefix that is assigned link-address An address with a prefix that is assigned
to the link from which the client should to the link from which the client should
be assigned an address. be assigned an address.
client-return-address The source address from the IP datagram client-return-address The IPv6 source address in which the
in which the message from the client was message from the client was received by
received by the relay agent the relay agent
options MUST include a "Client message option"; options MUST include a "Client message option";
see section 20.8; MAY include other see section 22.9; MAY include other
options added by the relay agent options added by the relay agent
9.2. Relay-reply message 9.2. Relay-reply message
The following table defines the use of message fields in a The following table defines the use of message fields in a
Relay-forward message. Relay-reply message.
msg-type RELAY-REPL msg-type RELAY-REPL
link-address An address with a prefix that is assigned link-address The link-address copied from the
to the link from which the client should Relay-forward message; used by the relay
be assigned an address. agent to select the link on which the
message is returned to the client
client-return-address The source address from the IP datagram client-return-address The source address from the IP datagram
in which the message from the client was in which the message from the client was
received by the relay agent received by the relay agent
options MUST include a "Server message option"; options MUST include a "Server message option";
see section 20.9; MAY include other see section 22.10; MAY include other
options options
10. DHCP unique identifier (DUID) 10. Representation and use of domain names
So that domain names may be encoded uniformly and compactly, a
domain name or a list of domain names is encoded using the technique
described in sections 3.1 and 4.1.4 of RFC1035 [15]. Section 4.1.4
of RFC1035 describes how more than one domain name can be represented
in a list of domain names. For use in this specification, in a
list of domain names, the compression pointer (see section 4.1.4 of
RFC1035) refers to the offset within the list.
If a single domain name is being used by a vendor as a vendor
identifier, then the vendor MUST ensure that the domain name has not
previously been used by a different vendor.
11. DHCP unique identifier (DUID)
Each DHCP client has a DUID. DHCP servers use DUIDs to identify Each DHCP client has a DUID. DHCP servers use DUIDs to identify
clients for the selection of configuration parameters and in clients for the selection of configuration parameters and in
the association of IAs with clients. See section 20.2 for the the association of IAs with clients. See section 22.2 for the
representation of a DUID in a DHCP message. representation of a DUID in a DHCP message.
Servers MUST treat DUIDs as opaque values and MUST only compare DUIDs Servers MUST treat DUIDs as opaque values and MUST only compare DUIDs
for equality. Servers MUST NOT in any other way interpret DUIDs. for equality. Servers MUST NOT in any other way interpret DUIDs.
Servers MUST NOT restrict DUIDs to the types defined in this document Servers MUST NOT restrict DUIDs to the types defined in this document
as additional DUID types may be defined in the future. as additional DUID types may be defined in the future.
The DUID is carried in an option because it may be variable length The DUID is carried in an option because it may be variable length
and because it is not required in all DHCP options (e.g., messages and because it is not required in all DHCP options (e.g., messages
sent by servers need not include a DUID). The DUID must be unique sent by servers need not include a DUID). The DUID is designed to
across all DHCP clients, and it must also be consistent for the same be unique across all DHCP clients, and consistent for any specific
client - that is, the DUID used by a client SHOULD NOT change over client - that is, the DUID used by a client SHOULD NOT change over
time; for example, as a result of network hardware reconfiguration. time, for example, as a result of network hardware reconfiguration.
The motivation for having more than one type of DUID is that the DUID The motivation for having more than one type of DUID is that the DUID
must be globally unique, and must also be easy to generate. The sort must be globally unique, and must also be easy to generate. The sort
of globally-unique identifier that is easy to generate for any given of globally-unique identifier that is easy to generate for any given
device can differ quite widely. Also, some devices may not contain device can differ quite widely. Also, some devices may not contain
any persistent storage. Retaining a generated DUID in such a device any persistent storage. Retaining a generated DUID in such a device
is not possible, so the DUID scheme must accommodate such devices. is not possible, so the DUID scheme must accommodate such devices.
10.1. DUID contents 11.1. DUID contents
A DUID consists of a sixteen-bit type code represented in network A DUID consists of a sixteen-bit type code represented in network
order, followed by a variable number of octets that make up the order, followed by a variable number of octets that make up the
actual identifier. A DUID can be no more than 256 octets long. The actual identifier. A DUID can be no more than 256 octets long. The
following types are currently defined: following types are currently defined:
1 Link-layer address plus time 1 Link-layer address plus time
2 Vendor-assigned unique ID 2 Vendor-assigned unique ID
3 Link-layer address 3 Link-layer address
Formats for the variable field of the DUID for each of the above Formats for the variable field of the DUID for each of the above
types are shown below. types are shown below.
10.2. DUID based on link-layer address plus time 11.2. DUID based on link-layer address plus time
This type of DUID consists of four octets containing a time value, This type of DUID consists of four octets containing a time value,
followed by a two octet network hardware type code, followed by followed by a two octet network hardware type code, followed by
link-layer address of any one network interface that is connected link-layer address of any one network interface that is connected
to the DHCP client device at the time that the DUID is generated. to the DHCP client device at the time that the DUID is generated.
The time value is the time that the DUID is generated represented The time value is the time that the DUID is generated represented
in seconds since midnight (UTC), January 1, 2000, modulo 2^32. The in seconds since midnight (UTC), January 1, 2000, modulo 2^32. The
hardware type MUST be a valid hardware type assigned by the IANA as hardware type MUST be a valid hardware type assigned by the IANA as
described in the section on ARP in RFC 826. Both the time and the described in the section on ARP in RFC 826. Both the time and the
hardware type are stored in network order. hardware type are stored in network order.
skipping to change at page 17, line 13 skipping to change at page 19, line 16
DUID should be used in configuring all network interfaces connected DUID should be used in configuring all network interfaces connected
to the device, regardless of which interface's link-layer address was to the device, regardless of which interface's link-layer address was
used to generate the DUID. used to generate the DUID.
DHCP clients using this type of DUID MUST store the DUID in stable DHCP clients using this type of DUID MUST store the DUID in stable
storage, and MUST continue to use this DUID even if the network storage, and MUST continue to use this DUID even if the network
interface used to generate the DUID is removed. DHCP clients that do interface used to generate the DUID is removed. DHCP clients that do
not have any stable storage MUST NOT use this type of DUID. not have any stable storage MUST NOT use this type of DUID.
DHCP clients that use this DUID SHOULD attempt to configure the time DHCP clients that use this DUID SHOULD attempt to configure the time
prior to generating the DUID, if that is possible, and MUST use some prior to generating the DUID, if that is possible, and MUST use
sort of time source (e.g., a real-time clock) in generating the some sort of time source (e.g., a real-time clock) in generating
DUID, even if that time source is not configured by the user prior the DUID, even if that time source could not be configured prior to
to generating the DUID. The use of a time source makes it unlikely generating the DUID. The use of a time source makes it unlikely that
that if the network interface is removed from the client and another two identical DUIDs will be generated if the network interface is
client then uses the same network interface to generate a DUID, removed from the client and another client then uses the same network
that two identical DUIDs will be generated. A DUID collision is interface to generate a DUID. A DUID collision is very unlikely even
very unlikely even if the clocks haven't been configured prior to if the clocks haven't been configured prior to generating the DUID.
generating the DUID.
This method of DUID generation is recommended for all general purpose This method of DUID generation is recommended for all general purpose
computing devices such as desktop computers and laptop computers, and computing devices such as desktop computers and laptop computers, and
also for devices such as printers, routers, and so on, that contain also for devices such as printers, routers, and so on, that contain
some form of writable non-volatile storage. some form of writable non-volatile storage.
10.3. Vendor-assigned unique ID. 11.3. Vendor-assigned unique ID
The vendor-assigned unique ID consists of an eight-octet The vendor-assigned unique ID consists of an eight-octet
vendor-unique identifier, followed by the vendor's registered domain vendor-unique identifier, followed by the vendor's registered domain
name. name.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VUID (64 bits) | | VUID (64 bits) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. domain name (variable length) . . domain name (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The structure of the VUID is left up to the vendor defining it, but The structure of the VUID is left up to the vendor defining it, but
each device containing such a VUID MUST be unique to each device each device containing such a VUID MUST be unique to each device
that is using it, and MUST be assigned to the device at the time of that is using it, and MUST be assigned to the device at the time of
manufacture and stored in some form of non-volatile storage. The manufacture and stored in some form of non-volatile storage. The
VUID SHOULD be recorded in non-erasable storage. The domain name is VUID SHOULD be recorded in non-erasable storage. The domain name
simply any domain name that has been legally registered by the vendor is simply any domain name that has been legally registered by the
in the domain name system, stored in canonical form. An example DUID vendor in the domain name system [14], stored in the form described
of this type might look like this: in section 10.
An example DUID of this type might look like this:
+--+---+---+---+-+-+-+--+---+---+--+---+---+---+---+--+--+---+---+ +--+---+---+---+-+-+-+--+---+---+--+---+---+---+---+--+--+---+---+
|12|192|132|221|3|0|9|18|101|120|97|109|112|108|101|46|99|111|109| |12|192|132|221|3|0|9|18|101|120|97|109|112|108|101|46|99|111|109|
+--+---+---+---+-+-+-+--+---+---+--+---+---+---+---+--+--+---+---+ +--+---+---+---+-+-+-+--+---+---+--+---+---+---+---+--+--+---+---+
This is eight octets of VUID data, followed by "example.com" This is eight octets of VUID data, followed by "example.com"
represented in ASCII. represented in ASCII.
10.4. Link-layer address 11.4. Link-layer address
This type of DUID consists of a two octet network hardware type code, This type of DUID consists of a two octet network hardware type code,
followed by the link-layer address of any one network interface that followed by the link-layer address of any one network interface that
is permanently connected to the DHCP client device. The hardware is permanently connected to the DHCP client device and cannot be
type MUST be a valid hardware type assigned by the IANA as described removed. The hardware type MUST be a valid hardware type assigned by
in the section on ARP in RFC 826. The hardware type is stored in the IANA as described in the section on ARP in RFC 826. The hardware
network order. type is stored in network order.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hardware type (16 bits) | | | Hardware type (16 bits) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. . . .
. link-layer address (variable length) . . link-layer address (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 18, line 45 skipping to change at page 20, line 47
interfaces connected to the device, regardless of which interface's interfaces connected to the device, regardless of which interface's
link-layer address was used to generate the DUID. link-layer address was used to generate the DUID.
This type of DUID is recommended for devices that have a This type of DUID is recommended for devices that have a
permanently-connected network interface with a link-layer address and permanently-connected network interface with a link-layer address and
do not have nonvolatile, writable stable storage. This type of DUID do not have nonvolatile, writable stable storage. This type of DUID
MUST NOT be used by DHCP clients that cannot tell whether or not a MUST NOT be used by DHCP clients that cannot tell whether or not a
network interface is permanently attached to the device on which the network interface is permanently attached to the device on which the
DHCP client is running. DHCP client is running.
11. Identity association 12. Identity association
An "identity-association" (IA) is a construct through which a server An "identity-association" (IA) is a construct through which a server
and a client can identify, group and manage IPv6 addresses. Each and a client can identify, group and manage IPv6 addresses. Each IA
IA consists of an IAID and associated configuration information. A consists of an IAID and associated configuration information.
client associates an IA with one of its interfaces and uses the IA to
obtain configuration information for that interface from a server. A client must associate at least one distinct IA with each of
its network interfaces and uses that IA to obtain configuration
information from a server for that interface. Other distinct IAs may
be associated with applications. Each IA must be associated with
exactly one interface.
The IAID uniquely identifies the IA and must be chosen to be unique
among the IAIDs on the client. The IAID is chosen by the client.
For any given use of an IA by the client, the IAID for that IA MUST
be consistent across restarts of the DHCP client. The client may
maintain consistency either by storing the IAID in non-volatile
storage or by using an algorithm that will consistently produce the
same IAID as long as the configuration of the client has not changed.
There may be no way for a client to maintain consistency of the IAIDs
if it does not have non-volatile storage and the client's hardware
configuration changes.
The configuration information in an IA consists of one or more IPv6 The configuration information in an IA consists of one or more IPv6
addresses and other parameters. The parameters are specified as DHCP addresses and other parameters. The parameters are specified as DHCP
options within the IA, and are associated with the addresses in the options within the IA, and are associated with the addresses in the
IA and the interface to which the IA belongs. Other parameters that IA and the interface to which the IA belongs. Other parameters that
are not associated with a particular interface may be specified in are not associated with a particular interface may be specified in
the options section of a DHCP message, outside the scope of any IA. the options section of a DHCP message, outside the scope of any IA.
Each address in an IA has a preferred lifetime and a valid lifetime, Each address in an IA has a preferred lifetime and a valid lifetime,
as defined in RFC2462 [20]. The lifetimes are transmitted from the as defined in RFC2462 [23]. The lifetimes are transmitted from the
DHCP server to the client in the IA option. The lifetimes apply to DHCP server to the client in the IA option. The lifetimes apply to
the use of IPv6 addresses as described in section 5.5.4 of RFC2462. the use of IPv6 addresses as described in section 5.5.4 of RFC2462.
An address whose valid lifetime has expired MAY be discarded from the An address whose valid lifetime has expired MAY be discarded from the
IA. IA.
See section 20.3 for the representation of an IA in a DHCP message. See section 22.3 for the representation of an IA in a DHCP message.
12. Selecting addresses for assignment to an IA 13. Selecting addresses for assignment to an IA
A server selects addresses to be assigned to an IA according to the A server selects addresses to be assigned to an IA according to the
address assignment policies determined by the server administrator address assignment policies determined by the server administrator
and the specific information the server determines about the client and the specific information the server determines about the client
from the following sources: from the following sources:
- The link to which the client is attached: - The link to which the client is attached:
* If the server receives the message directly from the client * If the server receives the message directly from the client
and the source address in the IP datagram in which the and the source address in the IP datagram in which the
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agent, then the client is on the same link as the one to agent, then the client is on the same link as the one to
which the interface identified by the link-address field in which the interface identified by the link-address field in
the message from the relay is attached the message from the relay is attached
- The DUID supplied by the client - The DUID supplied by the client
- Other information in options supplied by the client - Other information in options supplied by the client
- Other information in options supplied by the relay agent - Other information in options supplied by the relay agent
13. Reliability of Client Initiated Message Exchanges The addresses that the server selects for the client MUST be valid on
the link to which the interface is attached, regardless of the way in
which the server selects the addresses.
14. Management of temporary addresses
A client may be assigned temporary addresses [17]. Clients and
servers simply label addresses as "temporary". DHCPv6 handling
of address lifetimes and lifetime extensions is no different for
temporary addresses. DHCPv6 says nothing about details of temporary
addresses like lifetimes, lifetime extensions, how clients use
temporary addresses, rules for generating successive temporary
addresses, etc.
In DHCP, temporary addresses are identified with T-bit set in the IA
Address Option(see section 22.4). A client may have zero or more
temporary addresses. Addresses with the T-bit set MUST be intended
for the client to use for the general purposes described in RFC3041.
Addresses that otherwise have short lifetimes or are not intended to
be renewed by the server MUST NOT have the T-bit set.
Clients ask for temporary addresses and servers assign them. When a
client sends an IA to a server, the client lists all of the temporary
addresses it knows about and optionally indicates how many additional
temporary addresses it wants in the Requested Temporary Addresses
Option 22.5. The server compares the number of requested additional
temporary addresses against any previously allocated temporary
addresses for the IA that were not reported by the client in the
IA but still have some reasonable preferred lifetime left. If the
number of temporary addresses is less than the requested number, the
server adds additional temporary addresses to the IA to satisfy the
requested number (subject to server policy).
DISCUSSION:
It is important that the server include any allocated
temporary addresses that were not reported by the client as
it is possible the client never received an earlier Reply
that contained these additional temporary addresses. If
the server did not consider these, a client that fails to
receive a server's reply might cause the server to allocate
many temporary addresses.
When the valid lifetime on a temporary address expires, both the
client and server silently discard the address from the IA. The
discarded address no longer counts against the client's allotment of
temporary addresses.
A server SHOULD NOT assign a client temporary addresses without the
client having specifically asked for it. The client is not obligated
to install address(es) that it receives and did not request and can
release any addresses it does not want.
The server MAY update the DNS for a temporary address as described in
section 4 of RFC3041, and MUST NOT update the DNS in any other way
for a temporary address.
15. Reliability of Client Initiated Message Exchanges
DHCP clients are responsible for reliable delivery of messages in the DHCP clients are responsible for reliable delivery of messages in the
client-initiated message exchanges described in sections 15 and 16. client-initiated message exchanges described in sections 17 and 18.
If a DHCP client fails to receive an expected response from a server, If a DHCP client fails to receive an expected response from a server,
the client must retransmit its message. This section describes the the client must retransmit its message. This section describes the
retransmission strategy to be used by clients in client-initiated retransmission strategy to be used by clients in client-initiated
message exchanges. message exchanges.
Note that the procedure described in this section is slightly
modified for use with the Solicit message (section 17.1.2).
The client begins the message exchange by transmitting a message to The client begins the message exchange by transmitting a message to
the server. The message exchange terminates when either the client the server. The message exchange terminates when either the client
successfully receives the appropriate response or responses from a successfully receives the appropriate response or responses from a
server or servers, or when the message exchange is considered to have server or servers, or when the message exchange is considered to have
failed according to the retransmission mechanism described below. failed according to the retransmission mechanism described below.
The client retransmission behavior is controlled and describe by five The client retransmission behavior is controlled and described by the
variables: following variables:
RT Retransmission timeout RT Retransmission timeout
IRT Initial retransmission time IRT Initial retransmission time
MRC Maximum retransmission count MRC Maximum retransmission count
MRT Maximum retransmission time MRT Maximum retransmission time
MRD Maximum retransmission duration MRD Maximum retransmission duration
skipping to change at page 21, line 9 skipping to change at page 24, line 35
MRT specifies an upper bound on the value of RT. If MRT has a value MRT specifies an upper bound on the value of RT. If MRT has a value
of 0, there is no upper limit on the value of RT. Otherwise: of 0, there is no upper limit on the value of RT. Otherwise:
if (RT > MRT) if (RT > MRT)
RT = MRT + RAND*MRT RT = MRT + RAND*MRT
MRC specifies an upper bound on the number of times a client may MRC specifies an upper bound on the number of times a client may
retransmit a message. If MRC has a value of 0, the client MUST retransmit a message. If MRC has a value of 0, the client MUST
continue to retransmit the original message until a response is continue to retransmit the original message until a response is
received. Otherwise, the message exchange fails if the client received. Otherwise, the message exchange fails once the client has
attempts to transmit the original message more than MRC times. transmitted the message MRC times.
MRD specifies an upper bound on the length of time a client may MRD specifies an upper bound on the length of time a client may
retransmit a message. If MRD has a value of 0, the client MUST retransmit a message. If MRD has a value of 0, the client MUST
continue to retransmit the original message until a response is continue to retransmit the original message until a response is
received. Otherwise, the message exchange fails if the client received. Otherwise, the message exchange fails once the client has
attempts to transmit the original message more than MRD seconds. transmitted the message MRD seconds.
If both MRC and MRD are non-zero, the message exchange fails whenever If both MRC and MRD are non-zero, the message exchange fails whenever
either of the conditions specified in the previous paragraph are met. either of the conditions specified in the previous two paragraphs are
met.
Implementations SHOULD verify that for retransmissions that MRC,
MRT, and MRD are not all set to zero for any retransmission case.
14. Message validation 16. Message validation
Servers MUST discard any received messages that include Servers MUST discard any received messages that include
authentication information and fail the authentication check by the authentication information and fail the authentication check by the
server. server.
Clients MUST discard any received messages that include Clients MUST discard any received messages that include
authentication information and fail the authentication check by the authentication information and fail the authentication check by the
client, except as noted in section 19.6.5.2. client, except as noted in section 21.6.5.2.
14.1. Use of Transaction-ID field 16.1. Use of Transaction-ID field
The "transaction-ID" field holds a value used by clients and servers The "transaction-ID" field holds a value used by clients and servers
to synchronize server responses to client messages. A client SHOULD to synchronize server responses to client messages. A client SHOULD
choose a different transaction-ID for each new message it sends. A choose a different transaction-ID for each new message it sends. A
client MUST leave the transaction-ID unchanged in retransmissions of client MUST leave the transaction-ID unchanged in retransmissions of
a message. a message.
14.2. Solicit message 16.2. Solicit message
Clients MUST discard any received Solicit messages. Clients MUST discard any received Solicit messages.
Relay agents MUST discard any Solicit messages received through port Relay agents MUST discard any Solicit messages received through port
546. 546.
14.3. Advertise message 16.3. Advertise message
Clients MUST discard any received Advertise messages in which the Clients MUST discard any received Advertise messages in which the
"Transaction-ID" field value does not match the value the client used "Transaction-ID" field value does not match the value the client used
in its Solicit message. in its Solicit message.
Servers and relay agents MUST discard any received Advertise Servers and relay agents MUST discard any received Advertise
messages. messages.
14.4. Request message 16.4. Request message
Clients MUST discard any received Request messages. Clients MUST discard any received Request messages.
Relay agents MUST discard any Request messages received through port Relay agents MUST discard any Request messages received through port
546. 546.
Servers MUST discard any received Request message in which the value Servers MUST discard any received Request message in which the value
in the ``server-address'' field does not match any of the addresses in the "server-address" field does not match any of the addresses
used by the server. used by the server.
14.5. Confirm message 16.5. Confirm message
Clients MUST discard any received Confirm messages. Clients MUST discard any received Confirm messages.
Relay agents MUST discard any Confirm messages received through port Relay agents MUST discard any Confirm messages received through port
546. 546.
14.6. Renew message 16.6. Renew message
Clients MUST discard any received Renew messages. Clients MUST discard any received Renew messages.
Relay agents MUST discard any Renew messages received through port Relay agents MUST discard any Renew messages received through port
546. 546.
Servers MUST discard any received Renew message in which the value in Servers MUST discard any received Renew message in which the value in
the ``server-address'' field does not match any of the addresses used the "server-address" field does not match any of the addresses used
by the server. by the server.
14.7. Rebind message 16.7. Rebind message
Clients MUST discard any received Rebind messages. Clients MUST discard any received Rebind messages.
Relay agents MUST discard any Rebind messages received through port Relay agents MUST discard any Rebind messages received through port
546. 546.
14.8. Decline messages 16.8. Decline messages
Clients MUST discard any received Decline messages. Clients MUST discard any received Decline messages.
Relay agents MUST discard any Decline messages received through port Relay agents MUST discard any Decline messages received through port
546. 546.
Servers MUST discard any received Decline message in which the value Servers MUST discard any received Decline message in which the value
in the ``server-address'' field does not match any of the addresses in the "server-address" field does not match any of the addresses
used by the server. used by the server.
14.9. Release message 16.9. Release message
Clients MUST discard any received Release messages. Clients MUST discard any received Release messages.
Relay agents MUST discard any Release messages received through port Relay agents MUST discard any Release messages received through port
546. 546.
Servers MUST discard any received Release message in which the value Servers MUST discard any received Release message in which the value
in the ``server-address'' field does not match any of the addresses in the "server-address" field does not match any of the addresses
used by the server. used by the server.
14.10. Reply message 16.10. Reply message
Clients MUST discard any received Reply messages in which the Clients MUST discard any received Reply messages in which the
``transaction-ID'' field in the message does not match the value used "transaction-ID" field in the message does not match the value used
in the original message. in the original message.
Servers and relay agents MUST discard any received Reply messages. Servers and relay agents MUST discard any received Reply messages.
14.11. Reconfigure-init message 16.11. Reconfigure message
Servers and relay agents MUST discard any received Reconfigure-init Servers and relay agents MUST discard any received Reconfigure
messages. messages.
Clients MUST discard any Reconfigure-init messages that do not Clients MUST discard any Reconfigure messages that do not contain an
contain an authentication option or that fail the authentication authentication option or that fail the authentication performed by
performed by the client. the client.
14.12. Inform message 16.12. Inform message
Clients MUST discard any received Inform messages. Clients MUST discard any received Inform messages.
Relay agents MUST discard any Inform messages received through port Relay agents MUST discard any Inform messages received through port
546. 546.
14.13. Relay-forward message 16.13. Relay-forward message
Clients MUST discard any received Relay-forward messages. Clients MUST discard any received Relay-forward messages.
14.14. Relay-reply message 16.14. Relay-reply message
Clients and servers MUST discard any received Relay-reply messages. Clients and servers MUST discard any received Relay-reply messages.
15. DHCP Server Solicitation 17. DHCP Server Solicitation
This section describes how a client locates servers that will assign This section describes how a client locates servers that will assign
addresses to IAs belonging to the client. addresses to IAs belonging to the client.
The client is responsible for creating IAs and requesting that a The client is responsible for creating IAs and requesting that a
server assign configuration information, including IPv6 addresses, server assign configuration information, including IPv6 addresses,
to the IA. The client first creates an IA and assigns it an IAID. to the IA. The client first creates an IA and assigns it an IAID.
The client then transmits a Solicit message containing an IA option The client then transmits a Solicit message containing an IA option
describing the IA. Servers that can assign configuration information describing the IA. Servers that can assign configuration information
to the IA respond to the client with an Advertise message. The to the IA respond to the client with an Advertise message. The
client then initiates a configuration exchange as described in client then initiates a configuration exchange as described in
section 16. section 18.
15.1. Client Behavior 17.1. Client Behavior
A client uses the Solicit message to discover DHCP servers configured A client uses the Solicit message to discover DHCP servers configured
to serve addresses on the link to which the client is attached. to serve addresses on the link to which the client is attached.
15.1.1. Creation of Solicit messages 17.1.1. Creation of Solicit messages
The client sets the "msg-type" field to SOLICIT. The client generates The client sets the "msg-type" field to SOLICIT. The client generates
a transaction ID and inserts this value in the "transaction-ID" a transaction ID and inserts this value in the "transaction-ID"
field. field.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client MUST include IA options for any IAs to which server. The client MUST include one or more IA options for any IAs
it wants the server to assign addresses. The client MAY include to which it wants the server to assign addresses. The client MAY
addresses in the IAs as a hint to the server about addresses for include addresses in the IAs as a hint to the server about addresses
which the client may have a preference. The client MAY include for which the client has a preference. The client MAY include an
an Option Request Option in the Solicit message. The client MUST Option Request Option in the Solicit message. The client MUST NOT
NOT include any other options except those specifically allowed as include any other options except those specifically allowed as
defined by specific options. defined by specific options.
15.1.2. Transmission of Solicit Messages 17.1.2. Transmission of Solicit Messages
The client sends the Solicit message to the All_DHCP_Agents The client sends the Solicit message to the All_DHCP_Agents
multicast address. The client MUST use an IPv6 address assigned multicast address. The client MUST use an IPv6 address assigned
to the interface for which the client is interested in obtaining to the interface for which the client is interested in obtaining
configuration information as the source address in the IP header of configuration information as the source address in the IP header of
the datagram carrying the Solicit message. the datagram carrying the Solicit message.
The Solicit message MUST be transmitted on the link that the The Solicit message MUST be transmitted on the link that the
interface for which configuration information is being obtained interface for which configuration information is being obtained
is attached to. The client SHOULD send the message through that is attached to. The client SHOULD send the message through that
interface. The client MAY send the message through another interface interface. The client MAY send the message through another interface
attached to the same link if and only if the client is certain the attached to the same link if and only if the client is certain the
two interface are attached to the same link. two interface are attached to the same link.
The first Solicit message from the client on the interface MUST The first Solicit message from the client on the interface MUST
be delayed by a random amount of time between MIN_SOL_DELAY and be delayed by a random amount of time between MIN_SOL_DELAY and
MAX_SOL_DELAY. This random delay desynchronizes clients which start MAX_SOL_DELAY. This random delay desynchronizes clients which start
at the same time (e.g., after a power outage). at the same time (e.g., after a power outage).
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT SOL_TIMEOUT IRT SOL_TIMEOUT
MRT SOL_MAX_RT MRT SOL_MAX_RT
MRC 0 MRC 0
MRD 0 MRD 0
The mechanism in section 13 is modified as follows for use in the The mechanism in section 15 is modified as follows for use in the
transmission of Solicit messages. The message exchange is not transmission of Solicit messages. The message exchange is not
terminated by the receipt of an Advertise before SOL_TIMEOUT has terminated by the receipt of an Advertise before SOL_TIMEOUT has
elapsed. Rather, the client collects Advertise messages until elapsed. Rather, the client collects Advertise messages until
SOL_TIMEOUT has elapsed. The first RT MUST be selected to be SOL_TIMEOUT has elapsed. Also, the first RT MUST be selected to be
strictly greater than SOL_TIMEOUT by choosing RAND to be strictly strictly greater than SOL_TIMEOUT by choosing RAND to be strictly
greater than 0. greater than 0.
A client MUST collect Advertise messages for SOL_TIMEOUT seconds, A client MUST collect Advertise messages for SOL_TIMEOUT seconds,
unless it receives an Advertise message with a preference value unless it receives an Advertise message with a preference value
of 255. The preference value is carried in the Preference option of 255. The preference value is carried in the Preference option
(section 20.6). Any Solicit that does not include a Preference (section 22.7). Any Solicit that does not include a Preference
option is considered to have a preference value of 0. If the client option is considered to have a preference value of 0. If the client
receives an Advertise message with a preference value of 255, then receives an Advertise message with a preference value of 255, then
the client MAY act immediately on that Advertise message without the client MAY act immediately on that Advertise message without
waiting for any more additional Advertise messages. waiting for any additional Advertise messages.
A DHCP client SHOULD choose MRC and MRD to be 0. If the DHCP client A DHCP client SHOULD choose MRC and MRD to be 0. If the DHCP client
is configured with either MRC or MRD set to a value other than is configured with either MRC or MRD set to a value other than
0, it MUST stop trying to configure the interface if the message 0, it MUST stop trying to configure the interface if the message
exchange fails. After the DHCP client stops trying to configure the exchange fails. After the DHCP client stops trying to configure the
interface, it MAY choose to restart the reconfiguration process after interface, it SHOULD choose to restart the reconfiguration process
some external event, such as user input, system restart, or when the after some external event, such as user input, system restart, or
client is attached to a new link. when the client is attached to a new link.
15.1.3. Receipt of Advertise messages 17.1.3. Receipt of Advertise messages
The client MUST ignore any Advertise message that includes a Status The client MUST ignore any Advertise message that includes a Status
Code option containing the value AddrUnavail, with the exception that Code option containing the value AddrUnavail, with the exception that
the client MAY display the associated status message to the user. the client MAY display the associated status message to the user.
Upon receipt of one or more valid Advertise messages, the client Upon receipt of one or more valid Advertise messages, the client
selects one or more Advertise messages based upon the following selects one or more Advertise messages based upon the following
criteria. criteria.
- Those Advertise messages with the highest server preference value - Those Advertise messages with the highest server preference value
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preference value, addresses advertised, when the advertisement was preference value, addresses advertised, when the advertisement was
received, and so on. Depending on the requirements of the user that received, and so on. Depending on the requirements of the user that
invoked the DHCP client, the client MAY initiate a configuration invoked the DHCP client, the client MAY initiate a configuration
exchange with the server(s) immediately, or MAY defer this exchange exchange with the server(s) immediately, or MAY defer this exchange
until later. until later.
If the client needs to select an alternate server in the case that a If the client needs to select an alternate server in the case that a
chosen server does not respond, the client chooses the next server chosen server does not respond, the client chooses the next server
according to the criteria given above. according to the criteria given above.
15.2. Server Behavior 17.2. Server Behavior
A server sends an Advertise message in response to Solicit messages A server sends an Advertise message in response to Solicit messages
it receives to announce the availability of the server to the client. it receives to announce the availability of the server to the client.
15.2.1. Receipt of Solicit messages 17.2.1. Receipt of Solicit messages
The server determines the information about the client and its The server determines the information about the client and its
location as described in section 12. If administrative policy location as described in section 13. If administrative policy
permits the server to respond to the client, the server will generate permits the server to respond to the client, the server will generate
and send an Advertise message to the client. and send an Advertise message to the client.
15.2.2. Creation and transmission of Advertise messages 17.2.2. Creation and transmission of Advertise messages
The server sets the "msg-type" field to ADVERTISE and copies the The server sets the "msg-type" field to ADVERTISE and copies the
contents of the transaction-ID field from the Solicit message contents of the transaction-ID field from the Solicit message
received from the client to the Advertise message. The server places received from the client to the Advertise message. The server
one of its IP addresses (determined through administrator setting) places one of its IP addresses in the "server-address" field of the
in the "server-address" field of the Advertise message. The server Advertise message. The administrator must be able to configure the
MAY add a Preference option to carry the preference value for the address used in the "server-address" field. The server MAY add a
Advertise message. Preference option to carry the preference value for the Advertise
message.
The server implementation SHOULD allow the setting of a server The server implementation SHOULD allow the setting of a server
preference value by the administrator. The server preference value preference value by the administrator. The server preference value
MUST default to zero unless otherwise configured by the server MUST default to zero unless otherwise configured by the server
administrator. administrator.
The server MUST include IA options in the Advertise message The server MUST include IA options in the Advertise message
containing any addresses that would be assigned to IAs contained in containing any addresses that would be assigned to IAs contained in
the Solicit message from the client. The server MAY include some or the Solicit message from the client. The server MAY include some or
all of the IA options from the client in the Advertise message. all of the IA options from the client in the Advertise message.
If the server will not assign any addresses to IAs in a subsequent If the server will not assign any addresses to IAs in a subsequent
Request from the client, the server MAY either send an Advertise Request from the client, the server SHOULD either send an Advertise
message to the client that includes only a status code option with message to the client that includes only a status code option with
the status code set to AddrUnavail and a status message for the user the status code set to AddrUnavail and a status message for the user
or discard the Advertise message. or not respond to the Solicit message.
The server MAY include other options the server will return to the The server MAY include other options the server will return to the
client in a subsequent Reply message. The information in these client in a subsequent Reply message. The information in these
options will be used by the client in the selection of a server if options will be used by the client in the selection of a server if
the client receives more than one Advertise message. The server the client receives more than one Advertise message. The server
SHOULD include options specifying values for options requested by the SHOULD include options specifying values for options requested by the
client in an Option Request Option included in the Solicit message. client in an Option Request Option included in the Solicit message.
If the Solicit message was received directly by the server, the If the Solicit message was received directly by the server, the
server unicasts the Advertise message directly to the client using server unicasts the Advertise message directly to the client using
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be unicast through the interface on which the Solicit message was be unicast through the interface on which the Solicit message was
received. received.
If the Solicit message was received in a Relay-forward message, If the Solicit message was received in a Relay-forward message,
the server constructs a Relay-reply message with the Advertise the server constructs a Relay-reply message with the Advertise
message in the payload of a "server-message" option. The server message in the payload of a "server-message" option. The server
unicasts the Relay-reply message directly to the relay agent using unicasts the Relay-reply message directly to the relay agent using
the address in the source address field from the IP datagram in which the address in the source address field from the IP datagram in which
the Relay-forward message was received. the Relay-forward message was received.
16. DHCP Client-Initiated Configuration Exchange 18. DHCP Client-Initiated Configuration Exchange
A client initiates a message exchange with a server or servers to A client initiates a message exchange with a server or servers to
acquire or update configuration information of interest. The client acquire or update configuration information of interest. The client
may initiate the configuration exchange as part of the operating may initiate the configuration exchange as part of the operating
system configuration process or when requested to do so by the system configuration process or when requested to do so by the
application layer. application layer.
16.1. Client Behavior 18.1. Client Behavior
A client will use Request, Confirm, Renew, Rebind and Inform messages A client will use Request, Confirm, Renew, Rebind and Inform messages
to acquire and confirm the validity of configuration information. to acquire and confirm the validity of configuration information.
The client uses the server address information and information about The client uses the server address information and information about
IAs from previous Advertise messages for use in constructing Request IAs from previous Advertise messages for use in constructing Request
messages. Note that a client may request configuration information messages. Note that a client may request configuration information
from one or more servers at any time. from one or more servers at any time.
16.1.1. Creation and transmission of Request messages 18.1.1. Creation and transmission of Request messages
The client uses a Request message to populate IAs with addresses The client uses a Request message to populate IAs with addresses
and obtain other configuration information. The client includes and obtain other configuration information. The client includes
one or more IA options in the Request message, with addresses and one or more IA options in the Request message, with addresses and
information about the IAs that were obtained from the server in a information about the IAs that were obtained from the server in a
previous Advertise message. The server then returns addresses and previous Advertise message. The server then returns addresses and
other information about the IAs to the client in IA options in a other information about the IAs to the client in IA options in a
Reply message. Reply message.
The client generates a transaction ID and inserts this value in the The client generates a transaction ID and inserts this value in the
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The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client adds any other appropriate options, including server. The client adds any other appropriate options, including
one or more IA options (if the client is requesting that the server one or more IA options (if the client is requesting that the server
assign it some network addresses). The list of addresses in each assign it some network addresses). The list of addresses in each
included IA MUST include the addresses received by the client in a included IA MUST include the addresses received by the client in a
previous Advertise message. previous Advertise message.
If the client has a source address of sufficient scope that can be If the client has a source address of sufficient scope that can be
used by the server as a return address and the client has received used by the server as a return address and the client has received
a Client Unicast option (section 20.12) from the server, the client a Server Unicast option (section 22.14) from the server, the client
SHOULD unicast the Request message to the server. Otherwise, the SHOULD unicast the Request message to the server. Otherwise, the
client MUST send the Request message to the All_DHCP_Agents multicast client MUST send the Request message to the All_DHCP_Agents multicast
address. The client MUST use an address assigned to the interface address. The client MUST use an address assigned to the interface
for which the client is interested in obtaining configuration for which the client is interested in obtaining configuration
information as the source address in the IP header of the datagram information as the source address in the IP header of the datagram
carrying the Request message. carrying the Request message.
DISCUSSION: DISCUSSION:
Use of multicast and relay agents enables the inclusion of Use of multicast and relay agents enables the inclusion of
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agent options will not be used. agent options will not be used.
If the client multicasts the Request message, the message MUST be If the client multicasts the Request message, the message MUST be
transmitted on the link that the interface for which configuration transmitted on the link that the interface for which configuration
information is being obtained is attached to. The client SHOULD send information is being obtained is attached to. The client SHOULD send
the message through that interface. The client MAY send the message the message through that interface. The client MAY send the message
through another interface attached to the same link if and only if through another interface attached to the same link if and only if
the client is certain the the two interface are attached to the same the client is certain the the two interface are attached to the same
link. link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT REQ_TIMEOUT IRT REQ_TIMEOUT
MRT REQ_MAX_RT MRT REQ_MAX_RT
MRC REQ_MAX_RC MRC REQ_MAX_RC
MRD 0 MRD 0
If the message exchange fails, the client MAY choose one of the If the message exchange fails, the client MAY choose one of the
following actions: following actions:
- Select another server from a list of servers known to the client; - Select another server from a list of servers known to the client;
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MRC REQ_MAX_RC MRC REQ_MAX_RC
MRD 0 MRD 0
If the message exchange fails, the client MAY choose one of the If the message exchange fails, the client MAY choose one of the
following actions: following actions:
- Select another server from a list of servers known to the client; - Select another server from a list of servers known to the client;
e. g., servers that responded with an Advertise message e. g., servers that responded with an Advertise message
- Initiate the server discovery process described in section 15 - Initiate the server discovery process described in section 17
- Terminate the configuration process and report failure - Terminate the configuration process and report failure
16.1.2. Creation and transmission of Confirm messages 18.1.2. Creation and transmission of Confirm messages
Whenever a client may have moved to a new link, its IPv6 addresses Whenever a client may have moved to a new link, its IPv6 addresses
and other configuration information may no longer be valid. Examples and other configuration information may no longer be valid. Examples
of times when a client may have moved to a new link include: of times when a client may have moved to a new link include:
o The client reboots o The client reboots
o The client is physically disconnected from a wired connection o The client is physically disconnected from a wired connection
o The client returns from sleep mode o The client returns from sleep mode
o The client using a wireless technology changes links o The client using a wireless technology changes access points
In any situation when a client may have moved to a new link, the In any situation when a client may have moved to a new link, the
client MUST initiate a Confirm/Reply message exchange. The client client MUST initiate a Confirm/Reply message exchange. The client
includes any IAs, along with the addresses associated with those IAs, includes any IAs, along with the addresses associated with those IAs,
in its Confirm message. Any responding servers will indicate the in its Confirm message. Any responding servers will indicate the
acceptability of the addresses with the status in the Reply message acceptability of the addresses with the status in the Reply message
it returns to the client. it returns to the client.
The client sets the "msg-type" field to CONFIRM. The client generates The client sets the "msg-type" field to CONFIRM. The client generates
a transaction ID and inserts this value in the "transaction-ID" a transaction ID and inserts this value in the "transaction-ID"
field. field.
The client sets the "server-address" field to 0. The client sets the "server-address" field to 0.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client adds any appropriate options, including one or server. The client adds any appropriate options, including one or
more IA options. The client MUST include the addresses the client more IA options. The client MUST include the addresses the client
currently has associated with those IAs. currently has associated with those IAs.
The client sends the Confirm message to the All_DHCP_Agents The client sends the Confirm message to the All_DHCP_Agents multicast
multicast address. The client MUST use an IPv6 address assigned address. The client MUST use an IPv6 address that the client has
to the interface for which the client is interested in obtaining confirmed to be valid on the link to which it is currently attached
configuration information as the source address in the IP header of and that is assigned to the interface for which the client is
the datagram carrying the Confirm message. interested in obtaining configuration information as the source
address in the IP header of the datagram carrying the Confirm
message.
The Confirm message MUST be transmitted on the link that the The Confirm message MUST be transmitted on the link that the
interface for which configuration information is being obtained interface for which configuration information is being obtained
is attached to. The client SHOULD send the message through that is attached to. The client SHOULD send the message through that
interface. The client MAY send the message through another interface interface. The client MAY send the message through another interface
attached to the same link if and only if the client is certain the attached to the same link if and only if the client is certain the
the two interface are attached to the same link. the two interface are attached to the same link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT CNF_TIMEOUT IRT CNF_TIMEOUT
MRT CNF_MAX_RT MRT CNF_MAX_RT
MRC 0 MRC 0
MRD CNF_MAX_RD MRD CNF_MAX_RD
If the client receives no responses before the message transmission If the client receives no responses before the message transmission
process as described in section 13 terminates, the client SHOULD process as described in section 15 terminates, the client SHOULD
continue to use any IP addresses, using the last known lifetimes for continue to use any IP addresses, using the last known lifetimes for
those addresses, and SHOULD continue to use any other previously those addresses, and SHOULD continue to use any other previously
obtained configuration parameters. obtained configuration parameters.
16.1.3. Creation and transmission of Renew messages 18.1.3. Creation and transmission of Renew messages
To extend the valid and preferred lifetimes associated with To extend the valid and preferred lifetimes associated with
addresses, the client sends a Renew message to the server containing addresses, the client sends a Renew message to the server containing
an "IA option" for the IA and its associated addresses. The server an "IA option" for the IA and its associated addresses. The server
determines new lifetimes for the addresses in the IA according to the determines new lifetimes for the addresses in the IA according to the
administrative configuration of the server. The server may also add administrative configuration of the server. The server may also add
new addresses to the IA. The server may remove addresses from the IA new addresses to the IA. The server may remove addresses from the IA
by setting the preferred and valid lifetimes of those addresses to by setting the preferred and valid lifetimes of those addresses to
zero. zero.
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transaction ID and inserts this value in the "transaction-ID" field. transaction ID and inserts this value in the "transaction-ID" field.
The client places the address of the destination server in the The client places the address of the destination server in the
"server-address" field. "server-address" field.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client adds any appropriate options, including one or server. The client adds any appropriate options, including one or
more IA options (if the client is requesting that the server extend more IA options (if the client is requesting that the server extend
the lifetimes of the addresses assigned to those IAs; note that the the lifetimes of the addresses assigned to those IAs; note that the
client may check the status of other configuration parameters without client may check the status of other configuration parameters without
asking for lifetime extensions). If the client does include any IA asking for lifetime extensions). The client MUST include the list
options, it MUST include the list of addresses the client currently of addresses the client currently has associated with the IAs in the
has associated with that IA. Renew message.
If the client has a source address of sufficient scope that can be If the client has a source address of sufficient scope that can be
used by the server as a return address and the client has received used by the server as a return address and the client has received
a Client Unicast option (section 20.12) from the server, the client a Server Unicast option (section 22.14) from the server, the client
SHOULD unicast the Renew message to the server. Otherwise, the SHOULD unicast the Renew message to the server. Otherwise, the
client sends the Renew message to the All_DHCP_Agents multicast client sends the Renew message to the All_DHCP_Agents multicast
address. The client MUST use an address assigned to the interface address. The client MUST use an address assigned to the interface
for which the client is interested in obtaining configuration for which the client is interested in obtaining configuration
information as the source address in the IP header of the datagram information as the source address in the IP header of the datagram
carrying the Renew message. carrying the Renew message.
If the Renew message is multicast, it MUST be transmitted on the If the Renew message is multicast, it MUST be transmitted on the
link that the interface for which configuration information is being link that the interface for which configuration information is being
obtained is attached to. The client SHOULD send the message through obtained is attached to. The client SHOULD send the message through
that interface. The client MAY send the message through another that interface. The client MAY send the message through another
interface attached to the same link if and only if the client is interface attached to the same link if and only if the client is
certain the the two interface are attached to the same link. certain the the two interface are attached to the same link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT REN_TIMEOUT IRT REN_TIMEOUT
MRT REP_MAX_RT MRT REP_MAX_RT
MRC 0 MRC 0
MRD 0 MRD 0
The mechanism in section 13 is modified as follows for use in the The mechanism in section 15 is modified as follows for use in the
transmission of Renew messages. The message exchange is terminated transmission of Renew messages. The message exchange is terminated
when time T2 is reached (see section 16.1.4), at which time the when time T2 is reached (see section 18.1.4), at which time the
client begins a Rebind message exchange. client begins a Rebind message exchange.
16.1.4. Creation and transmission of Rebind messages 18.1.4. Creation and transmission of Rebind messages
At time T2 for an IA (which will only be reached if the server to At time T2 for an IA (which will only be reached if the server to
which the Renew message was sent at time T1 has not responded), which the Renew message was sent at time T1 has not responded),
the client initiates a Rebind/Reply message exchange. The client the client initiates a Rebind/Reply message exchange. The client
includes an IA option with all addresses currently assigned to the includes an IA option with all addresses currently assigned to the
IA in its Rebind message. The client sends this message to the IA in its Rebind message. The client sends this message to the
All_DHCP_Agents multicast address. All_DHCP_Agents multicast address.
The client sets the "msg-type" field to REBIND. The client generates The client sets the "msg-type" field to REBIND. The client generates
a transaction ID and inserts this value in the "transaction-ID" a transaction ID and inserts this value in the "transaction-ID"
field. field.
The client sets the "server-address" field to 0. The client sets the "server-address" field to 0.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client adds any appropriate options, including one or server. The client adds any appropriate options, including one or
more IA options. If the client does include any IA options (if more IA options. The client MUST include the list of addresses the
the client is requesting that the server extend the lifetimes of client currently has associated with the IAs in the Rebind message.
addresses assigned to those IAs; note that the client may check
the status of other configuration parameters without asking for
lifetime extensions), it MUST include the list of addresses the
client currently has associated with that IA.
The client sends the Rebind message to the All_DHCP_Agents The client sends the Rebind message to the All_DHCP_Agents
multicast address. The client MUST use an IPv6 address assigned multicast address. The client MUST use an IPv6 address assigned
to the interface for which the client is interested in obtaining to the interface for which the client is interested in obtaining
configuration information as the source address in the IP header of configuration information as the source address in the IP header of
the datagram carrying the Rebind message. the datagram carrying the Rebind message.
The Rebind message MUST be transmitted on the link that the interface The Rebind message MUST be transmitted on the link that the interface
for which configuration information is being obtained is attached for which configuration information is being obtained is attached
to. The client SHOULD send the message through that interface. The to. The client SHOULD send the message through that interface. The
client MAY send the message through another interface attached to the client MAY send the message through another interface attached to the
same link if and only if the client is certain the the two interface same link if and only if the client is certain the the two interface
are attached to the same link. are attached to the same link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT REB_TIMEOUT IRT REB_TIMEOUT
MRT REB_MAX_RT MRT REB_MAX_RT
MRC 0 MRC 0
MRD 0 MRD 0
The mechanism in section 13 is modified as follows for use in the The mechanism in section 15 is modified as follows for use in the
transmission of Rebind messages. The message exchange is terminated transmission of Rebind messages. The message exchange is terminated
when the lifetimes on the addresses assigned to the IA expire (see when the lifetimes of all of the addresses assigned to the IA expire
section 11), at which time the client has several alternative actions (see section 12), at which time the client has several alternative
to choose from: actions to choose from:
- The client may choose to use a Solicit message to locate a new - The client may choose to use a Solicit message to locate a new
DHCP server and send a Request for the expired IA to the new DHCP server and send a Request for the expired IA to the new
server server
- The client may have other addresses in other IAs, so the client - The client may have other addresses in other IAs, so the client
may choose to discard the expired IA and use the addresses in the may choose to discard the expired IA and use the addresses in the
other IAs other IAs
16.1.5. Creation and Transmission of Inform messages 18.1.5. Creation and Transmission of Inform messages
The client uses an Inform message to obtain configuration information The client uses an Inform message to obtain configuration information
without having addresses assigned to it. The client sets the without having addresses assigned to it. The client sets the
"msg-type" field to INFORM. The client generates a transaction ID and "msg-type" field to INFORM. The client generates a transaction ID and
inserts this value in the "transaction-ID" field. inserts this value in the "transaction-ID" field.
The client sets the "server-address" field to 0. The client sets the "server-address" field to 0.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client adds any appropriate options such as an ORO to server. The client adds any appropriate options such as an ORO to
indicate to the server what configuration information the client is indicate to the server what configuration information the client is
interested in obtaining. interested in obtaining. The client MUST NOT include any IA options.
The client MUST use an IPv6 address assigned to the interface for The client MUST use an IPv6 address assigned to the interface for
which the client is interested in obtaining configuration information which the client is interested in obtaining configuration information
as the source address in the IP header of the datagram carrying the as the source address in the IP header of the datagram carrying the
Rebind message. Rebind message.
If the client has an IPv6 address of sufficient scope, the If the client has an IPv6 address of sufficient scope, the client MAY
client MAY choose to send the Inform message to the Allmulticast choose to send the Inform message to the All_DHCP_Servers multicast
address. Otherwise, the client MUST send the Inform message to the address. Otherwise, the client MUST send the Inform message to the
All_DHCP_Agents multicast address. All_DHCP_Agents multicast address.
The Inform message MUST be transmitted on the link that the interface The Inform message MUST be transmitted on the link that the interface
for which configuration information is being obtained is attached for which configuration information is being obtained is attached
to. The client SHOULD send the message through that interface. The to. The client SHOULD send the message through that interface. The
client MAY send the message through another interface attached to the client MAY send the message through another interface attached to the
same link if and only if the client is certain the the two interface same link if and only if the client is certain the the two interface
are attached to the same link. are attached to the same link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT INF_TIMEOUT IRT INF_TIMEOUT
MRT INF_MAX_RT MRT INF_MAX_RT
MRC 0 MRC 0
MRD 0 MRD 0
16.1.6. Receipt of Reply message in response to a Request, Confirm, 18.1.6. Receipt of Reply message in response to a Request, Confirm,
Renew, Rebind or Inform message Renew, Rebind or Inform message
Upon the receipt of a valid Reply message in response to a Upon the receipt of a valid Reply message in response to a Request,
Request, Confirm, Renew or Rebind message, the client extracts the Confirm, Renew, Rebind or Inform message, the client extracts the
configuration information contained in the Reply. The client MAY configuration information contained in the Reply. The client MAY
choose to report any status code or message from the status code choose to report any status code or message from the status code
option in the Reply message. option in the Reply message.
The client SHOULD perform duplicate address detection [20] on each of The client SHOULD perform duplicate address detection [23] on each
the addresses in any IAs it receives in the Reply message. If any of of the addresses in any IAs it receives in the Reply message after
the addresses are found to be in use on the link, the client sends a a Request message. If any of the addresses are found to be in use
Decline message to the server as described in section 16.1.9. on the link, the client sends a Decline message to the server as
described in section 18.1.9.
The client records the T1 and T2 times for each IA in the Reply The client records the T1 and T2 times for each IA in the Reply
message. The client records any addresses included with IAs in message. The client records any addresses included with IAs in
the Reply message. The client updates the preferred and valid the Reply message. The client updates the preferred and valid
lifetimes for the addresses in the IA from the lifetime information lifetimes for the addresses in the IA from the lifetime information
in the IA option. The client leaves any addresses that the client in the IA option. The client leaves any addresses that the client
has associated with the IA that are not included in the IA option has associated with the IA that are not included in the IA option
unchanged. unchanged.
The client SHOULD respond to the server with a Release message for
any addresses in the Reply message that have a valid lifetime of 0.
The client constructs and transmits this message as described in
section 18.1.7.
If the Reply was received in response to a Renew or Rebind message, If the Reply was received in response to a Renew or Rebind message,
the client must update the information in any IA option contained in the client must update the information in any IA option contained in
the Reply message. The client adds any new addresses from the IA the Reply message. The client adds any new addresses from the IA
option to the IA, updates lifetimes for existing addresses in the IA option to the IA, updates lifetimes for existing addresses in the IA
from the IA option and discards any addresses with a lifetime of zero from the IA option and discards any addresses with a lifetime of zero
in the IA option. in the IA option.
Management of the specific configuration information is detailed in Management of the specific configuration information is detailed in
the definition of each option, in section 20. the definition of each option, in section 22.
When the client receives a NoPrefixMatch status in an IA from the When the client receives a NoPrefixMatch status in an IA from the
server the client can assume it needs to send a Request to the server server the client can assume it needs to send a Request to the server
to obtain appropriate addresses for the IA. If the client receives to obtain appropriate addresses for the IA. If the client receives
any Reply messages that do not indicate a NoPrefixMatch status, the any Reply messages that do not indicate a NoPrefixMatch status, the
client can use the addresses in the IA and ignore any messages that client can use the addresses in the IA and ignore any messages that
do indicate a NoPrefixMatch status. do indicate a NoPrefixMatch status.
When the client receives an AddrUnavail status in an IA from the When the client receives an AddrUnavail status in an IA from the
server for a Request message the client will have to find a new server for a Request message the client will have to find a new
server to create an IA. server to create an IA.
When the client receives a NoBinding status status in an IA from the When the client receives a NoBinding status in an IA from the server
server for a Confirm message the client can assume it needs to send a for a Confirm message the client can assume it needs to send a
Request to reestablish an IA with the server. Request to reestablish an IA with the server.
When the client receives a ConfNoMatch status in an IA from the When the client receives a ConfNoMatch status in an IA from the
server for a Confirm message the client can send a Renew message to server for a Confirm message the client can send a Renew message to
the server to extend the lifetimes of the addresses. the server to extend the lifetimes of the addresses.
When the client receives a NoBinding status in an IA from the server When the client receives a NoBinding status in an IA from the server
for a Renew message the client can assume it needs to send a Request for a Renew message the client can assume it needs to send a Request
to reestablish an IA with the server. to reestablish an IA with the server.
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to reestablish an IA with the server or try another server. to reestablish an IA with the server or try another server.
When the client receives a RebdNoMatch status in an IA from the When the client receives a RebdNoMatch status in an IA from the
server for a Rebind message the client can assume it needs to send a server for a Rebind message the client can assume it needs to send a
Request to reestablish an IA with the server or try another server. Request to reestablish an IA with the server or try another server.
When the client receives an AddrUnavail status in an IA from the When the client receives an AddrUnavail status in an IA from the
server for a Rebind message the client can assume it needs to send a server for a Rebind message the client can assume it needs to send a
Request to reestablish an IA with the server or try another server. Request to reestablish an IA with the server or try another server.
16.1.7. Creation and transmission of Release messages 18.1.7. Creation and transmission of Release messages
The client sets the "msg-type" field to RELEASE. The client generates The client sets the "msg-type" field to RELEASE. The client generates
a transaction ID and places this value in the "transaction-ID" field. a transaction ID and places this value in the "transaction-ID" field.
The client places the IP address of the server that allocated the The client places the IP address of the server that allocated the
address(es) in the "server-address" field. address(es) in the "server-address" field.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client includes options containing the IAs it is server. The client includes options containing the IAs it is
releasing in the "options" field. The addresses to be released releasing in the "options" field. The addresses to be released
MUST be included in the IAs. The client continues to use any other MUST be included in the IAs. The client continues to use any other
addresses in the IA. The appropriate "status" field in the options addresses in the IAs. The appropriate "status" field in the options
MUST be set to indicate the reason for the release. MUST be set to indicate the reason for the release.
The client MUST NOT use any of the addresses in the IAs in the The client MUST NOT use any of the addresses in the IAs in the
message as the source address in the Release message or in any message as the source address in the Release message or in any
subsequently transmitted message. subsequently transmitted message.
If the client has a source address of sufficient scope that can be If the client has a source address of sufficient scope that can be
used by the server as a return address and the client has received used by the server as a return address and the client has received
a Client Unicast option (section 20.12) from the server, the client a Server Unicast option (section 22.14) from the server, the client
SHOULD unicast the Release message to the server. Otherwise, the SHOULD unicast the Release message to the server. Otherwise, the
client MUST send the Release message to the All_DHCP_Agents multicast client MUST send the Release message to the All_DHCP_Agents multicast
address. The client MUST use an address for the interface to which address. The client MUST use an address for the interface to which
the IAs in the Release message are assigned as the source address for the IAs in the Release message are assigned as the source address for
the Release message. the Release message.
DISCUSSION: DISCUSSION:
Use of multicast and relay agents enables the inclusion of Use of multicast and relay agents enables the inclusion of
relay agent options in all messages sent by the client. The relay agent options in all messages sent by the client. The
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link that the interface for which configuration information is being link that the interface for which configuration information is being
obtained is attached to. The client SHOULD send the message through obtained is attached to. The client SHOULD send the message through
that interface. The client MAY send the message through another that interface. The client MAY send the message through another
interface attached to the same link if and only if the client is interface attached to the same link if and only if the client is
certain the the two interface are attached to the same link. certain the the two interface are attached to the same link.
A client MAY choose to wait for a Reply message from the server in A client MAY choose to wait for a Reply message from the server in
response to the Release message. If the client does wait for a response to the Release message. If the client does wait for a
Reply, the client MAY choose to retransmit the Release message. Reply, the client MAY choose to retransmit the Release message.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT REL_TIMEOUT IRT REL_TIMEOUT
MRT 0 MRT 0
MRC REL_MAX_MRC MRC REL_MAX_MRC
MRD 0 MRD 0
The client MUST abandon the attempt to release addresses if the The client MUST abandon the attempt to release addresses if the
Release message exchange fails. Release message exchange fails.
The client MUST stop using all of the addresses in the IA(s) being The client MUST stop using all of the addresses in the IA(s) being
released as soon as the client begins the Release message exchange released as soon as the client begins the Release message exchange
process. If an IA is released but the Reply from a DHCP server process. If an IA is released but the Reply from a DHCP server
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is lost, the client will retransmit the Release message, and the is lost, the client will retransmit the Release message, and the
server may respond with a Reply indicating a status of "Nobinding". server may respond with a Reply indicating a status of "Nobinding".
Therefore, the client does not treat a Reply message with a status Therefore, the client does not treat a Reply message with a status
of "Nobinding" in a Release message exchange as if it indicates an of "Nobinding" in a Release message exchange as if it indicates an
error. error.
Note that if the client fails to release the IA, the addresses Note that if the client fails to release the IA, the addresses
assigned to the IA will be reclaimed by the server when the lifetime assigned to the IA will be reclaimed by the server when the lifetime
of the address expires. of the address expires.
16.1.8. Receipt of Reply message in response to a Release message 18.1.8. Receipt of Reply message in response to a Release message
Upon receipt of a valid Reply message, the client can consider the Upon receipt of a valid Reply message, the client can consider the
Release event successful. Release event successful.
16.1.9. Creation and transmission of Decline messages 18.1.9. Creation and transmission of Decline messages
The client sets the "msg-type" field to DECLINE. The client generates The client sets the "msg-type" field to DECLINE. The client generates
a transaction ID and places this value in the "transaction-ID" field. a transaction ID and places this value in the "transaction-ID" field.
The client places the IP address of the server that allocated the The client places the IP address of the server that allocated the
address(es) in the "server-address" field. address(es) in the "server-address" field.
The client MUST include a DUID option to identify itself to the The client MUST include a DUID option to identify itself to the
server. The client includes options containing the IAs it is server. The client includes options containing the IAs it is
declining in the "options" field. The addresses to be declined MUST declining in the "options" field. The addresses to be declined MUST
be included in the IAs. The client continues to use other addresses be included in the IAs. The client continues to use other addresses
in the IAs. The appropriate "status" field in the options MUST be in the IAs. The appropriate "status" field in the options MUST be
set to indicate the reason for declining the address. set to indicate the reason for declining the address.
The client MUST NOT use any of the addresses in the IAs in the The client MUST NOT use any of the addresses in the IAs in the
message as the source address in the Decline message or in any message as the source address in the Decline message or in any
subsequently transmitted message. subsequently transmitted message.
If the client has a source address of sufficient scope that can be If the client has a source address of sufficient scope that can be
used by the server as a return address and the client has received used by the server as a return address and the client has received
a Client Unicast option (section 20.12) from the server, the client a Server Unicast option (section 22.14) from the server, the client
SHOULD unicast the Decline message to the server. Otherwise, the SHOULD unicast the Decline message to the server. Otherwise, the
client MUST send the Decline message to the All_DHCP_Agents multicast client MUST send the Decline message to the All_DHCP_Agents multicast
address. The client MUST use an IPv6 address for the interface to address. The client MUST use an IPv6 address for the interface to
which the IAs in the Decline message are assigned as the source which the IAs in the Decline message are assigned as the source
address for the Decline message. address for the Decline message.
DISCUSSION: DISCUSSION:
Use of multicast and relay agents enables the inclusion of Use of multicast and relay agents enables the inclusion of
relay agent options in all messages sent by the client. The relay agent options in all messages sent by the client. The
server MUST NOT enable the use of unicast for a client when server MUST NOT enable the use of unicast for a client when
relay agent options are required for that client. relay agent options are required for that client.
If the Decline message is multicast, it MUST be transmitted on the If the Decline message is multicast, it MUST be transmitted on the
link that the interface for which configuration information is being link that the interface for which configuration information is being
obtained is attached to. The client SHOULD send the message through obtained is attached to. The client SHOULD send the message through
that interface. The client MAY send the message through another that interface. The client MAY send the message through another
interface attached to the same link if and only if the client is interface attached to the same link if and only if the client is
certain the the two interface are attached to the same link. certain the the two interface are attached to the same link.
The client transmits the message according to section 13, using the The client transmits the message according to section 15, using the
following parameters: following parameters:
IRT DEC_TIMEOUT IRT DEC_TIMEOUT
MRT DEC_MAX_RT MRT DEC_MAX_RT
MRC DEC_MAX_RC MRC DEC_MAX_RC
MRD 0 MRD 0
The client MUST abandon the attempt to decline addresses if the The client MUST abandon the attempt to decline addresses if the
Decline message exchange fails. Decline message exchange fails.
16.1.10. Receipt of Reply message in response to a Decline message 18.1.10. Receipt of Reply message in response to a Decline message
Upon receipt of a valid Reply message, the client can consider the Upon receipt of a valid Reply message, the client can consider the
Decline event successful. Decline event successful.
16.2. Server Behavior 18.2. Server Behavior
For this discussion, the Server is assumed to have been configured in For this discussion, the Server is assumed to have been configured in
an implementation specific manner with configuration of interest to an implementation specific manner with configuration of interest to
clients. clients.
16.2.1. Receipt of Request messages 18.2.1. Receipt of Request messages
The server MAY choose to discard Request messages received via The server MAY choose to discard Request messages received via
unicast from a client to which the server has not sent a unicast unicast from a client to which the server has not sent a unicast
option. option.
When the server receives a Request and IA option(s) are included the When the server receives a Request the client is requesting the
client is requesting the configuration of a new IA by the server. configuration of a new IA by the server. The server MUST take the
The server MUST take the IA from the client and associate a binding IA from the client and associate a binding for that client in an
for that client in an implementation-specific manner within the implementation-specific manner within the configuration parameter
configuration parameter database for DHCP clients managed by the database for DHCP clients managed by the server.
server.
Upon the receipt of a valid Request message from a client the server Upon the receipt of a valid Request message from a client the server
can respond to, (implementation-specific administrative policy can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. satisfied) the server scans the options field.
The server then constructs a Reply message and sends it to the The server then constructs a Reply message and sends it to the
client. client.
The server SHOULD process each option for the client in an The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply implementation-specific manner. The server MUST construct a Reply
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the Reply message with the status field set to AddrUnavail and no the Reply message with the status field set to AddrUnavail and no
addresses in the IA. addresses in the IA.
For any IAs to which the server can assign addresses, server includes For any IAs to which the server can assign addresses, server includes
the IA with addresses and other configuration parameters a status of the IA with addresses and other configuration parameters a status of
Success, and add the IA as a new client binding. Success, and add the IA as a new client binding.
The server adds options to the Reply message for any other The server adds options to the Reply message for any other
configuration information to be assigned to the client. configuration information to be assigned to the client.
16.2.2. Receipt of Confirm messages 18.2.2. Receipt of Confirm messages
When the server receives a Confirm message, the client is requesting When the server receives a Confirm message, the client is requesting
confirmation that the configuration information it will use is valid. confirmation that the configuration information it will use is valid.
The server SHOULD locate the binding for that client and compare the The server SHOULD locate the binding for that client and compare the
information in the Confirm message from the client to the information information in the Confirm message from the client to the information
associated with that client. associated with that client.
Upon the receipt of a valid Confirm message from a client the server Upon the receipt of a valid Confirm message from a client the server
can respond to, (implementation-specific administrative policy can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. satisfied) the server scans the options field.
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transaction-ID The transaction-ID from the Confirm message. transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface server address One of the IP addresses assigned to the interface
through which the server received the message through which the server received the message
from the client. from the client.
The Reply message from the server MUST contain a Status Code option The Reply message from the server MUST contain a Status Code option
and MUST NOT include any other options. and MUST NOT include any other options.
16.2.3. Receipt of Renew messages 18.2.3. Receipt of Renew messages
The server MAY choose to discard Renew messages received via unicast The server MAY choose to discard Renew messages received via unicast
from a client to which the server has not sent a unicast option. from a client to which the server has not sent a unicast option.
Upon the receipt of a valid Renew message from a client the server Upon the receipt of a valid Renew message from a client the server
can respond to, (implementation-specific administrative policy can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. satisfied) the server scans the options field.
When the server receives a Renew and IA option from a client it When the server receives a Renew and IA option from a client it
SHOULD locate the clients binding and verify the information in the SHOULD locate the clients binding and verify the information in the
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T1/T2 times if the default is not being used, and set status to T1/T2 times if the default is not being used, and set status to
Success. The server may choose to change the list of addresses and Success. The server may choose to change the list of addresses and
the lifetimes of addresses in IAs that are returned to the client. the lifetimes of addresses in IAs that are returned to the client.
The server SHOULD process each option for the client in an The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply implementation-specific manner. The server MUST construct a Reply
message containing the following values: message containing the following values:
msg-type REPLY msg-type REPLY
transaction-ID The transaction-ID from the Renew message. transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface server address One of the IP addresses assigned to the interface
through which the server received the message through which the server received the message
from the client. from the client.
16.2.4. Receipt of Rebind messages 18.2.4. Receipt of Rebind messages
Upon the receipt of a valid Rebind message from a client the server Upon the receipt of a valid Rebind message from a client the server
can respond to, (implementation-specific administrative policy can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. satisfied) the server scans the options field.
When the server receives a Rebind and IA option from a client it When the server receives a Rebind and IA option from a client it
SHOULD locate the clients binding and verify the information in the SHOULD locate the clients binding and verify the information in the
IA from the client matches the information stored for that client. IA from the client matches the information stored for that client.
If the server cannot find a client entry for this IA the server If the server cannot find a client entry for this IA the server
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server SHOULD send back the IA to the client with new lifetimes and server SHOULD send back the IA to the client with new lifetimes and
T1/T2 times if the default is not being used, and set status to T1/T2 times if the default is not being used, and set status to
Success. Success.
The server SHOULD process each option for the client in an The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply implementation-specific manner. The server MUST construct a Reply
message containing the following values: message containing the following values:
msg-type REPLY msg-type REPLY
transaction-ID The transaction-ID from the Rebind message. transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface server address One of the IP addresses assigned to the interface
through which the server received the message through which the server received the message
from the client. from the client.
There is a significant difference between Renew and Rebind messages: 18.2.5. Receipt of Inform messages
Because the Renew message is processed by a single server, the
responding server can actually change the addresses in the IA.
However, because multiple servers may respond to a Rebind, all they
can safely do is update T1, T2 (for the IA) and lifetimes (for
individual addresses).
16.2.5. Receipt of Inform messages
When the server receives an Inform message, the client is requesting When the server receives an Inform message, the client is requesting
configuration information that does not include the assignment of any configuration information that does not include the assignment of any
addresses. The server SHOULD determine all configuration parameters addresses. The server SHOULD determine all configuration parameters
appropriate to the client, based on the server configuration policies appropriate to the client, based on the server configuration policies
known to the server. known to the server.
Upon the receipt of a valid Inform message from a client the server Upon the receipt of a valid Inform message from a client the server
can respond to, (implementation-specific administrative policy can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. The server then satisfied) the server scans the options field. The server then
constructs a Reply message and sends it to the client. constructs a Reply message and sends it to the client.
The server SHOULD process each option for the client in an The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply implementation-specific manner. The server MUST construct a Reply
message containing the following values: message containing the following values:
msg-type REPLY msg-type REPLY
transaction-ID The transaction-ID from the Inforrm message. transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface server address One of the IP addresses assigned to the interface
through which the server received the message through which the server received the message
from the client. from the client.
The server adds options to the Reply message for all of the The server adds options to the Reply message for all of the
configuration parameters to be returned to the client. configuration parameters to be returned to the client.
16.2.6. Receipt of Release messages 18.2.6. Receipt of Release messages
The server MAY choose to discard Release messages received via The server MAY choose to discard Release messages received via
unicast from a client to which the server has not sent a unicast unicast from a client to which the server has not sent a unicast
option. option.
Upon the receipt of a valid Release message, the server examines the Upon the receipt of a valid Release message, the server examines the
IAs and the addresses in the IAs for validity. If the IAs in the IAs and the addresses in the IAs for validity. If the IAs in the
message are in a binding for the client and the addresses in the IAs message are in a binding for the client and the addresses in the IAs
have been assigned by the server to those IAs, the server deletes have been assigned by the server to those IAs, the server deletes
the addresses from the IAs and makes the addresses available for the addresses from the IAs and makes the addresses available for
assignment to other clients. assignment to other clients. The server ignores invalid addresses
(though it may choose to log an error if it finds an invalid
address).
If all of the IAs were valid and the addresses successfully released, After all the addresses have been processed, the server generates a
the server generates a Reply message and includes a Status Code Reply message and includes a Status Code option with value Success.
option with value Success. The server MUST NOT include any other The server MUST NOT include any other options in the Reply message.
options in the Reply message.
A server is not required to (but may choose to as an implementation A server is not required to (but may choose to as an implementation
strategy) retain any record of an IA from which all of the addresses strategy) retain any record of an IA from which all of the addresses
have been released. have been released.
16.2.7. Receipt of Decline messages 18.2.7. Receipt of Decline messages
The server MAY choose to discard Decline messages received via The server MAY choose to discard Decline messages received via
unicast from a client to which the server has not sent a unicast unicast from a client to which the server has not sent a unicast
option. option.
Upon the receipt of a valid Decline message, the server examines the Upon the receipt of a valid Decline message, the server examines the
IAs and the addresses in the IAs for validity. If the IAs in the IAs and the addresses in the IAs for validity. If the IAs in the
message are in a binding for the client and the addresses in the IAs message are in a binding for the client and the addresses in the IAs
have been assigned by the server to those IA, the server deletes have been assigned by the server to those IA, the server deletes
the addresses from the IAs. The server SHOULD mark the addresses the addresses from the IAs. The server SHOULD mark the addresses
declined by the client so that those addresses are not assigned to declined by the client so that those addresses are not assigned to
other clients, and MAY choose to make a notification that addresses other clients, and MAY choose to make a notification that addresses
were declined. were declined. The server ignores invalid addresses (though it may
choose to log an error if it finds an invalid address).
If all of the IAs were valid and the addresses successfully declined, After all the address have been processed, the server generates a
the server generates a Reply message and includes a Status Code Reply message and includes a Status Code option with value Success.
option with value Success. The server MUST NOT include any other The server MUST NOT include any other options in the Reply message.
options in the Reply message.
16.2.8. Receipt of Decline messages 18.2.8. Receipt of Information-Request messages
Upon the receipt of a valid Inform message, the server determines the Upon the receipt of a valid Inform message, the server determines the
appropriate configuration parameters and returns those parameters to appropriate configuration parameters and returns those parameters to
the client in a Reply message. The server MUST NOT include any IA the client in a Reply message. The server MUST NOT include any IA
options in the Reply message. options in the Reply message.
16.2.9. Sending of Reply messages 18.2.9. Sending of Reply messages
If the Request, Confirm, Renew, Rebind, Release, Decline or Inform If the Request, Confirm, Renew, Rebind, Release, Decline or Inform
message from the client was originally received in a Relay-forward message from the client was originally received in a Relay-forward
message from a relay, the server places the Reply message in the message from a relay, the server places the Reply message in the
options field of a Relay-response message and copies the link-address options field of a Relay-response message and copies the link-address
and client-return-address fields from the Relay-forward message into and client-return-address fields from the Relay-forward message into
the Relay-response message. the Relay-response message.
The server then unicasts the Reply or Relay-reply to the source The server then unicasts the Reply or Relay-reply to the source
address from the IP datagram in which the original message was address from the IP datagram in which the original message was
received. received.
17. DHCP Server-Initiated Configuration Exchange 19. DHCP Server-Initiated Configuration Exchange
A server initiates a configuration exchange to cause DHCP clients A server initiates a configuration exchange to cause DHCP clients
to obtain new addresses and other configuration information. For to obtain new addresses and other configuration information. For
example, an administrator may use a server-initiated configuration example, an administrator may use a server-initiated configuration
exchange when links in the DHCP domain are to be renumbered. Other exchange when links in the DHCP domain are to be renumbered. Other
examples include changes in the location of directory servers, examples include changes in the location of directory servers,
addition of new services such as printing, and availability of new addition of new services such as printing, and availability of new
software (system or application). software (system or application).
17.1. Server Behavior 19.1. Server Behavior
A server sends a Reconfigure-init message to cause a client to A server sends a Reconfigure message to cause a client to initiate
initiate immediately a Rebind/Reply message exchange with the server. immediately a Renew/Reply or Information-request/Reply message
exchange with the server.
17.1.1. Creation and transmission of Reconfigure-init messages 19.1.1. Creation and transmission of Reconfigure messages
The server sets the "msg-type" field to RECONFIG-INIT. The server The server sets the "msg-type" field to RECONFIGURE. The server
generates a transaction-ID and inserts it in the "transaction-ID" generates a transaction-ID and inserts it in the "transaction-ID"
field. The server places its address (of appropriate scope) in the field. The server places its address (of appropriate scope) in the
"server-address" field. "server-address" field.
The server MAY include an ORO option to inform the client of what The server MAY include an ORO option to inform the client of what
information has been changed or new information that has been added. information has been changed or new information that has been added.
In particular, the server specifies the IA option in the ORO if the In particular, the server specifies the IA option in the ORO if the
server wants the client to obtain new address information. server wants the client to obtain new address information.
The server MUST include an authentication option with the appropriate The server MUST include an authentication option with the appropriate
settings and add that option as the last option in the "options" settings and add that option as the last option in the "options"
field of the Reconfigure-init message. field of the Reconfigure message.
The server MUST NOT include any other options in the Reconfigure-init The server MUST NOT include any other options in the Reconfigure
except as specifically allowed in the definition of individual except as specifically allowed in the definition of individual
options. options.
A server sends each Reconfigure-init message to a single DHCP client, A server sends each Reconfigure message to a single DHCP client,
using an IPv6 unicast address of sufficient scope belonging to the using an IPv6 unicast address of sufficient scope belonging to the
DHCP client. The server may obtain the address of the client through DHCP client. The server may obtain the address of the client through
the information that the server has about clients that have been in the information that the server has about clients that have been in
contact with the server, or the server may be configured with the contact with the server, or the server may be configured with the
address of the client through some external agent. address of the client through some external agent.
To reconfigure more than one client, the server unicasts a separate To reconfigure more than one client, the server unicasts a separate
message to each client. The server may initiate the reconfiguration message to each client. The server may initiate the reconfiguration
of multiple clients concurrently; for example, a server may send of multiple clients concurrently; for example, a server may
a Reconfigure-init message to additional clients while previous send a Reconfigure message to additional clients while previous
reconfiguration message exchanges are still in progress. reconfiguration message exchanges are still in progress.
The Reconfigure-init message causes the client to initiate a The Reconfigure message causes the client to initiate a Renew/Reply
Rebind/Reply message exchange with the server. The server interprets or Information-request/Reply message exchange with the server. The
the receipt of a Rebind message from the client as satisfying the server interprets the receipt of a Renew or Information-request
Reconfigure-init message request. message from the client as satisfying the Reconfigure message
request.
17.1.2. Time out and retransmission of Reconfigure-init messages 19.1.2. Time out and retransmission of Reconfigure messages
If the server does not receive a Rebind message from the client If the server does not receive a Renew or Information-request message
in RECREP_MSG_TIMEOUT milliseconds, the server retransmits from the client in RECREP_MSG_TIMEOUT milliseconds, the server
the Reconfigure-init message, doubles the RECREP_MSG_TIMEOUT retransmits the Reconfigure message, doubles the RECREP_MSG_TIMEOUT
value and waits again. The server continues this process until value and waits again. The server continues this process until
REC_MSG_ATTEMPTS unsuccessful attempts have been made, at which point REC_MSG_ATTEMPTS unsuccessful attempts have been made, at which point
the server SHOULD abort the reconfigure process for that client. the server SHOULD abort the reconfigure process for that client.
Default and initial values for RECREP_MSG_TIMEOUT and Default and initial values for RECREP_MSG_TIMEOUT and
REC_MSG_ATTEMPTS are documented in section 7.5. REC_MSG_ATTEMPTS are documented in section 7.5.
17.1.3. Receipt of Rebind messages 19.1.3. Receipt of Renew messages
The server generates and sends Reply message(s) to the client as The server generates and sends Reply message(s) to the client as
described in section 16.2.9, including in the "options" field new described in section 18.2.9, including in the "options" field new
values for configuration parameters. values for configuration parameters.
It is possible that the client may send a Rebind message after the It is possible that the client may send a Renew message after the
server has sent a Reconfigure-init but before the Reconfigure-init is server has sent a Reconfigure but before the Reconfigure is received
received by the client. In this case, the Rebind message from the by the client. In this case, the Renew message from the client
client may not include all of the IAs and requests for parameters to may not include all of the IAs and requests for parameters to be
be reconfigured by the server. To accommodate this scenario, the reconfigured by the server. To accommodate this scenario, the server
server MAY choose to send a Reply with the IAs and other parameters MAY choose to send a Reply with the IAs and other parameters to be
to be reconfigured, even if those IAs and parameters were not in the reconfigured, even if those IAs and parameters were not in the Renew
Rebind message from the client. message from the client.
17.2. Client Behavior 19.2. Receipt of Information-request messages
A client MUST always monitor UDP port 546 for Reconfigure-init If the server has assigned addresses to one or more IAs that belong
messages on interfaces upon which it has acquired DHCP parameters. to the responding client, the server MUST silently discard the
Since the results of a reconfiguration event may affect application Information-request message.
layer programs, the client SHOULD log these events, and MAY notify
these programs of the change through an implementation-specific
interface.
17.2.1. Receipt of Reconfigure-init messages The server generates and sends Reply message(s) to the client as
described in section 18.2.9, including in the "options" field new
values for configuration parameters.
Upon receipt of a valid Reconfigure-init message, the client It is possible that the client may send an Information-request
initiates a Rebind/Reply transaction with the server. While the message after the server has sent a Reconfigure but before
Rebind/Reply transaction is in progress, the client silently discards the Reconfigure is received by the client. In this case, the
any Reconfigure-init messages it receives. Information-request message from the client may not include all of
the IAs and requests for parameters to be reconfigured by the server.
To accommodate this scenario, the server MAY choose to send a Reply
with the IAs and other parameters to be reconfigured, even if those
IAs and parameters were not in the Information-request message from
the client.
19.3. Client Behavior
A client MUST always monitor UDP port 546 for Reconfigure messages
on interfaces for which it has acquired DHCP parameters. Since the
results of a reconfiguration event may affect application layer
programs, the client SHOULD log these events, and MAY notify these
programs of the change through an implementation-specific interface.
19.3.1. Receipt of Reconfigure messages
Upon receipt of a valid Reconfigure message, the client initiates a
transaction with the server. While the transaction is in progress,
the client silently discards any Reconfigure messages it receives.
If the client has IAs with addresses that have been assigned by the
server from which the Reconfigure message was received, the client
MUST respond with a Renew message. Otherwise, the client responds
with an Information-request message.
DISCUSSION: DISCUSSION:
The Reconfigure-init message acts as a trigger that signals The Reconfigure message acts as a trigger that signals the
the client to complete a successful Rebind/Reply message client to complete a successful message exchange. Once
exchange. Once the client has received a Reconfigure-init, the client has received a Reconfigure, the client proceeds
the client proceeds with the Rebind/Reply message with the message exchange (retransmitting the Renew or
exchange (retransmitting the Rebind if necessary); the Information-request message if necessary); the client
client ignores any additional Reconfigure-init messages ignores any additional Reconfigure messages (regardless
(regardless of the transaction ID in the Reconfigure-init of the transaction ID in the Reconfigure message) until
message) until the Rebind/Reply exchange is complete. the exchange is complete. Subsequent Reconfigure messages
Subsequent Reconfigure-init messages (again independent (again independent of the transaction ID) cause the client
of the transaction ID) cause the client to initiate a new to initiate a new exchange.
Rebind/Reply exchange.
How does this mechanism work in the face of duplicated How does this mechanism work in the face of duplicated or
or retransmitted Reconfigure-init messages? Duplicate retransmitted Reconfigure messages? Duplicate messages
messages will be ignored because the client will begin will be ignored because the client will begin the exchange
the Rebind/Reply exchange after the receipt of the after the receipt of the first Reconfigure. Retransmitted
first Reconfigure-init. Retransmitted messages will messages will either trigger the exchange (if the first
either trigger the Rebind/Reply exchange (if the first Reconfigure was not received by the client) or will be
Reconfigure-init was not received by the client) or will ignored. The server can discontinue retransmission of
be ignored. The server can discontinue retransmission of Reconfigure messages to the client once the server receives
Reconfigure-init messages to the client once the server the Renew or Information-request message from the client.
receives the Rebind from the client.
It might be possible for a duplicate or retransmitted It might be possible for a duplicate or retransmitted
Reconfigure-init to be sufficiently delayed (and delivered Reconfigure to be sufficiently delayed (and delivered out of
out of order) to arrive at the client after the Rebind/Reply order) to arrive at the client after the exchange (initiated
exchange (initiated by the original Reconfigure-init) has by the original Reconfigure) has been completed. In this
been completed. In this case, the client would initiate a case, the client would initiate a redundant exchange. The
redundant Rebind/Reply exchange. The likelihood of delayed likelihood of delayed and out of order delivery is small
and out of order delivery is small enough to be ignored. enough to be ignored. The consequence of the redundant
exchange is inefficiency rather than incorrect operation.
The consequence of the redundant exchange is inefficiency 19.3.2. Creation and sending of Renew messages
rather than incorrect operation.
17.2.2. Creation and sending of Rebind messages When responding to a Reconfigure, the client creates and sends
the Renew message in exactly the same manner as outlined in
section 18.1.3, with the exception: if the server included on ORO
option specifying the IA option, the client MUST include IA options
containing the addresses the client currently has assigned to ALL IAs
for the interface through which the Reconfigure message was received.
When responding to a Reconfigure-init, the client creates and 19.3.3. Creation and sending of Renew messages
sends the Rebind message in exactly the same manner as outlined in
section 16.1.1 with the following difference:
IAs The client includes IA options containing the addresses the When responding to a Reconfigure, the client creates and sends the
client currently has assigned to those IAs for the interface Information-request message in exactly the same manner as outlined in
through which the Reconfigure-init message was received. section 18.1.5.
17.2.3. Time out and retransmission of Rebind messages 19.3.4. Time out and retransmission of Renew or Information-request
messages
The client uses the same variables and retransmission algorithm as The client uses the same variables and retransmission algorithm as it
it does with Rebind messages generated as part of a client-initiated does with Rebind or Information-request messages generated as part
configuration exchange. See section 16.1.1 for details. of a client-initiated configuration exchange. See section 18.1.3
and 18.1.5 for details.
17.2.4. Receipt of Reply messages 19.3.5. Receipt of Reply messages
Upon the receipt of a valid Reply message, the client extracts the Upon the receipt of a valid Reply message, the client extracts the
contents of the "options" field, and sets (or resets) configuration contents of the "options" field, and sets (or resets) configuration
parameters appropriately. The client records and updates the parameters appropriately. The client records and updates the
lifetimes for any addresses specified in IAs in the Reply message. lifetimes for any addresses specified in IAs in the Reply message.
If the configuration parameters changed were requested by the If the configuration parameters changed were requested by the
application layer, the client notifies the application layer of the application layer, the client notifies the application layer of the
changes using an implementation-specific interface. changes using an implementation-specific interface.
As discussed in section 17.1.3, the Reply from the server may include 20. Relay Behavior
IAs and parameters that were not included in the Rebind message from
the client. The client MUST configure itself with all of the IAs and
parameters in the Reply from the server.
18. Relay Behavior
For this discussion, the Relay MAY be configured to use a list of For this discussion, the Relay MAY be configured to use a list of
server destination addresses, which MAY include unicast addresses, server destination addresses, which MAY include unicast addresses,
the All_DHCP_Servers multicast address, or other multicast addresses the All_DHCP_Servers multicast address, or other multicast addresses
selected by the network administrator. If the Relay has not been selected by the network administrator. If the Relay has not been
explicitly configured, it MUST use the All_DHCP_Servers multicast explicitly configured, it MUST use the All_DHCP_Servers multicast
address as the default. address as the default.
18.1. Relaying of client messages 20.1. Relaying of client messages
When a Relay receives a valid client message, it constructs a When a Relay receives a valid client message, it constructs a
Relay-forward message. The relay places an address with a prefix Relay-forward message. The relay places an address with a prefix
assigned to the link on which the client should be assigned an assigned to the link on which the client should be assigned an
address in the link-address field. This address will be used by the address in the link-address field. This address will be used by the
server to determine the link from which the client should be assigned server to determine the link from which the client should be assigned
an address and other configuration information. an address and other configuration information.
If the relay cannot use the address in the link-address field to If the relay cannot use the address in the link-address field to
identify the interface through which the response to the client identify the interface through which the response to the client
will be forwarded, the relay MUST include a circuit-id option (see will be forwarded, the relay MUST include a circuit-id option (see
section 20.16)in the Relay-forward message. The server will include section 22.18)in the Relay-forward message. The server will include
the circuit-id option in its Relay-reply message. the circuit-id option in its Relay-reply message.
The relay copies the source address from the IP datagram in which the The relay copies the source address from the IP datagram in which the
message was received from the client into the client-return-address message was received from the client into the client-return-address
field in the Relay-forward message. field in the Relay-forward message.
The relay constructs a "client-message" option 20.8 that contains The relay constructs a "client-message" option 22.9 that contains
the entire message from the client in the data field of the the entire message from the client in the data field of the
option. The relay places the "relay-message" option along with any option. The relay places the "relay-message" option along with any
"relay-specific" options in the options field of the Relay-forward "relay-specific" options in the options field of the Relay-forward
message. The Relay then sends the Relay-forward message to the list message. The Relay MUST send the Relay-forward message to the list
of server destination addresses that it has been configured with. of server destination addresses that it has been configured with and
MUST NOT send the message just to the server (if present) identified
in the server-address field in the client message.
18.2. Relaying of server messages 20.2. Relaying of server messages
When the relay receives a Relay-reply message, it extracts the server When the relay receives a Relay-reply message, it extracts the server
message from the "server-message" option. If the Relay-reply message message from the "server-message" option. If the Relay-reply message
includes a circuit-id option, the relay forwards the message from the includes a circuit-id option, the relay forwards the message from the
server to the client on the link identified by the circuit-id option. server to the client on the link identified by the circuit-id option.
Otherwise, the relay forwards the message on the link identified Otherwise, the relay forwards the message on the link identified
by the link-address field. In either case, the relay forwards the by the link-address field. In either case, the relay forwards the
message to the address in the client-return-address field in the message to the address in the client-return-address field in the
Relay-reply message. Relay-reply message.
19. Authentication of DHCP messages 21. Authentication of DHCP messages
Some network administrators may wish to provide authentication of Some network administrators may wish to provide authentication of
the source and contents of DHCP messages. For example, clients may the source and contents of DHCP messages. For example, clients may
be subject to denial of service attacks through the use of bogus be subject to denial of service attacks through the use of bogus
DHCP servers, or may simply be misconfigured due to unintentionally DHCP servers, or may simply be misconfigured due to unintentionally
instantiated DHCP servers. Network administrators may wish to instantiated DHCP servers. Network administrators may wish to
constrain the allocation of addresses to authorized hosts to avoid constrain the allocation of addresses to authorized hosts to avoid
denial of service attacks in "hostile" environments where the network denial of service attacks in "hostile" environments where the network
medium is not physically secured, such as wireless networks or medium is not physically secured, such as wireless networks or
college residence halls. college residence halls.
Because of the risk of denial of service attacks against DHCP Because of the risk of denial of service attacks against DHCP
clients, the use of authentication is mandated in Reconfigure-init clients, the use of authentication is mandated in Reconfigure
messages. A DHCP server MUST include an authentication option in messages. A DHCP server MUST include an authentication option in
Reconfigure-init messages sent to clients. Reconfigure messages sent to clients.
The DHCP authentication mechanism is based on the design of The DHCP authentication mechanism is based on the design of
authentication for DHCP for IPv4 [8]. authentication for DHCP for IPv4 [9].
19.1. DHCP threat model 21.1. DHCP threat model
The threat to DHCP is inherently an insider threat (assuming a The threat to DHCP is inherently an insider threat (assuming a
properly configured network where DHCPv6 ports are blocked on the properly configured network where DHCPv6 ports are blocked on the
perimeter gateways of the enterprise). Regardless of the gateway perimeter gateways of the enterprise). Regardless of the gateway
configuration, however, the potential attacks by insiders and configuration, however, the potential attacks by insiders and
outsiders are the same. outsiders are the same.
The attack specific to a DHCP client is the possibility of the The attack specific to a DHCP client is the possibility of the
establishment of a "rogue" server with the intent of providing establishment of a "rogue" server with the intent of providing
incorrect configuration information to the client. The motivation incorrect configuration information to the client. The motivation
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"theft of service", or to circumvent auditing for any number of "theft of service", or to circumvent auditing for any number of
nefarious purposes. nefarious purposes.
The threat common to both the client and the server is the resource The threat common to both the client and the server is the resource
"denial of service" (DoS) attack. These attacks typically involve "denial of service" (DoS) attack. These attacks typically involve
the exhaustion of valid addresses, or the exhaustion of CPU or the exhaustion of valid addresses, or the exhaustion of CPU or
network bandwidth, and are present anytime there is a shared network bandwidth, and are present anytime there is a shared
resource. In current practice, redundancy mitigates DoS attacks the resource. In current practice, redundancy mitigates DoS attacks the
best. best.
19.2. Security of messages sent between servers and relay agents 21.2. Security of messages sent between servers and relay agents
Relay agents and servers that choose to exchange messages securely Relay agents and servers that choose to exchange messages securely
use the IPsec mechanisms for IPv6 [10]. The way in which IPsec use the IPsec mechanisms for IPv6 [11]. The way in which IPsec
is employed by relay agents and servers is not specified in this is employed by relay agents and servers is not specified in this
document. document.
19.3. Summary of DHCP authentication 21.3. Summary of DHCP authentication
Authentication of DHCP messages is accomplished through the use of Authentication of DHCP messages is accomplished through the use of
the Authentication option. The authentication information carried the Authentication option. The authentication information carried
in the Authentication option can be used to reliably identify the in the Authentication option can be used to reliably identify the
source of a DHCP message and to confirm that the contents of the DHCP source of a DHCP message and to confirm that the contents of the DHCP
message have not been tampered with. message have not been tampered with.
The Authentication option provides a framework for multiple The Authentication option provides a framework for multiple
authentication protocols. Two such protocols are defined here. authentication protocols. Two such protocols are defined here.
Other protocols defined in the future will be specified in separate Other protocols defined in the future will be specified in separate
documents. documents.
The protocol field in the Authentication option identifies the The protocol field in the Authentication option identifies the
specific protocol used to generate the authentication information specific protocol used to generate the authentication information
carried in the option. The algorithm field identifies a specific carried in the option. The algorithm field identifies a specific
algorithm within the authentication protocol; for example, the algorithm within the authentication protocol; for example, the
algorithm field specifies the hash algorithm used to generate the algorithm field specifies the hash algorithm used to generate the
message authentication code (MAC) in the authentication option. The message authentication code (MAC) in the authentication option. The
replay detection method (RDM) field specifies the type of replay replay detection method (RDM) field specifies the type of replay
skipping to change at page 49, line 14 skipping to change at page 53, line 17
The protocol field in the Authentication option identifies the The protocol field in the Authentication option identifies the
specific protocol used to generate the authentication information specific protocol used to generate the authentication information
carried in the option. The algorithm field identifies a specific carried in the option. The algorithm field identifies a specific
algorithm within the authentication protocol; for example, the algorithm within the authentication protocol; for example, the
algorithm field specifies the hash algorithm used to generate the algorithm field specifies the hash algorithm used to generate the
message authentication code (MAC) in the authentication option. The message authentication code (MAC) in the authentication option. The
replay detection method (RDM) field specifies the type of replay replay detection method (RDM) field specifies the type of replay
detection used in the replay detection field. detection used in the replay detection field.
19.4. Replay detection 21.4. Replay detection
The Replay Detection Method (RDM) field determines the type of replay The Replay Detection Method (RDM) field determines the type of replay
detection used in the Replay Detection field. detection used in the Replay Detection field.
If the RDM field contains 0x00, the replay detection field MUST be If the RDM field contains 0x00, the replay detection field MUST be
set to the value of a monotonically increasing counter. Using a set to the value of a monotonically increasing counter. Using a
counter value such as the current time of day (e.g., an NTP-format counter value such as the current time of day (e.g., an NTP-format
timestamp [12]) can reduce the danger of replay attacks. This method timestamp [13]) can reduce the danger of replay attacks. This method
MUST be supported by all protocols. MUST be supported by all protocols.
19.5. Configuration token protocol 21.5. Configuration token protocol
If the protocol field is 0, the authentication information field If the protocol field is 0, the authentication information field
holds a simple configuration token. The configuration token is an holds a simple configuration token. The configuration token is an
opaque, unencoded value known to both the sender and receiver. The opaque, unencoded value known to both the sender and receiver. The
sender inserts the configuration token in the DHCP message and the sender inserts the configuration token in the DHCP message and the
receiver matches the token from the message to the shared token. If receiver matches the token from the message to the shared token. If
the configuration option is present and the token from the message the configuration option is present and the token from the message
does not match the shared token, the receiver MUST discard the does not match the shared token, the receiver MUST discard the
message. message.
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protection against inadvertently instantiated DHCP servers. protection against inadvertently instantiated DHCP servers.
DISCUSSION: DISCUSSION:
The intent here is to pass a constant, non-computed token The intent here is to pass a constant, non-computed token
such as a plain-text password. Other types of entity such as a plain-text password. Other types of entity
authentication using computed tokens such as Kerberos authentication using computed tokens such as Kerberos
tickets or one-time passwords will be defined as separate tickets or one-time passwords will be defined as separate
protocols. protocols.
19.6. Delayed authentication protocol 21.6. Delayed authentication protocol
If the protocol field is 1, the message is using the "delayed If the protocol field is 1, the message is using the "delayed
authentication" mechanism. In delayed authentication, the client authentication" mechanism. In delayed authentication, the client
requests authentication in its Solicit message and the server replies requests authentication in its Solicit message and the server replies
with an Advertise message that includes authentication information. with an Advertise message that includes authentication information.
This authentication information contains a nonce value generated by This authentication information contains a nonce value generated by
the source as a message authentication code (MAC) to provide message the source as a message authentication code (MAC) to provide message
authentication and entity authentication. authentication and entity authentication.
The use of a particular technique based on the HMAC protocol [11] The use of a particular technique based on the HMAC protocol [12]
using the MD5 hash [19] is defined here. using the MD5 hash [21] is defined here.
19.6.1. Management issues in the delayed authentication protocol 21.6.1. Management issues in the delayed authentication protocol
The "delayed authentication" protocol does not attempt to address The "delayed authentication" protocol does not attempt to address
situations where a client may roam from one administrative domain situations where a client may roam from one administrative domain
to another, i.e. interdomain roaming. This protocol is focused on to another, i.e. interdomain roaming. This protocol is focused on
solving the intradomain problem where the out-of-band exchange of a solving the intradomain problem where the out-of-band exchange of a
shared secret is feasible. shared secret is feasible.
19.6.2. Use of the Authentication option in the delayed authentication 21.6.2. Use of the Authentication option in the delayed authentication
protocol protocol
In a Solicit message, the Authentication option carries the Protocol, In a Solicit message, the Authentication option carries the Protocol,
Algorithm, RDM and Replay detection fields, but no Authentication Algorithm, RDM and Replay detection fields, but no Authentication
information. information.
In an Advertise, Request, Renew, Rebind or Confirm message, the In an Advertise, Request, Renew, Rebind, Confirm, Decline, Release
Authentication option carries the Protocol, Algorithm, RDM and Replay or Information-request message, the Authentication option carries
detection fields and Authentication information. The format of the the Protocol, Algorithm, RDM and Replay detection fields and
Authentication information is: Authentication information. The format of the Authentication
information is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Secret ID (32 bits) | | Secret ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| HMAC-MD5 (128 bits) | | HMAC-MD5 (128 bits) |
| | | |
| | | |
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authentication information for delayed authentication, algorithm 1: authentication information for delayed authentication, algorithm 1:
Replay Detection - as defined by the RDM field Replay Detection - as defined by the RDM field
K - a secret value shared between the source and K - a secret value shared between the source and
destination of the message; each secret has a destination of the message; each secret has a
unique identifier (secret ID) unique identifier (secret ID)
secret ID - the unique identifier for the secret value secret ID - the unique identifier for the secret value
used to generate the MAC for this message used to generate the MAC for this message
HMAC-MD5 - the MAC generating function. HMAC-MD5 - the MAC generating function.
The sender computes the MAC using the HMAC generation algorithm [11] The sender computes the MAC using the HMAC generation algorithm [12]
and the MD5 hash function [19]. The entire DHCP message (except and the MD5 hash function [21]. The entire DHCP message (except
the MAC field of the authentication option itself), including the the MAC field of the authentication option itself), including the
DHCP message header and the options field, is used as input to the DHCP message header and the options field, is used as input to the
HMAC-MD5 computation function. The 'secret ID' field MUST be set to HMAC-MD5 computation function. The 'secret ID' field MUST be set to
the identifier of the secret used to generate the MAC. the identifier of the secret used to generate the MAC.
DISCUSSION: DISCUSSION:
Algorithm 1 specifies the use of HMAC-MD5. Use of a Algorithm 1 specifies the use of HMAC-MD5. Use of a
different technique, such as HMAC-SHA, will be specified as different technique, such as HMAC-SHA, will be specified as
a separate protocol. a separate protocol.
Delayed authentication requires a shared secret key for each Delayed authentication requires a shared secret key for each
client on each DHCP server with which that client may wish client on each DHCP server with which that client may wish
to use the DHCP protocol. Each secret key has a unique to use the DHCP protocol. Each secret key has a unique
identifier that can be used by a receiver to determine which identifier that can be used by a receiver to determine which
secret was used to generate the MAC in the DHCP message. secret was used to generate the MAC in the DHCP message.
Therefore, delayed authentication may not scale well in an Therefore, delayed authentication may not scale well in an
architecture in which a DHCP client connects to multiple architecture in which a DHCP client connects to multiple
administrative domains. administrative domains.
19.6.3. Message validation 21.6.3. Message validation
To validate an incoming message, the receiver first checks that To validate an incoming message, the receiver first checks that
the value in the replay detection field is acceptable according the value in the replay detection field is acceptable according
to the replay detection method specified by the RDM field. Next, to the replay detection method specified by the RDM field. Next,
the receiver computes the MAC as described in [11]. The receiver the receiver computes the MAC as described in [12]. The receiver
MUST set the 'MAC' field of the authentication option to all 0s for MUST set the 'MAC' field of the authentication option to all 0s for
computation of the MAC. If the MAC computed by the receiver does not computation of the MAC. If the MAC computed by the receiver does not
match the MAC contained in the authentication option, the receiver match the MAC contained in the authentication option, the receiver
MUST discard the DHCP message. MUST discard the DHCP message.
19.6.4. Key utilization 21.6.4. Key utilization
Each DHCP client has a key, K. The client uses its key to encode Each DHCP client has a key, K. The client uses its key to encode
any messages it sends to the server and to authenticate and verify any messages it sends to the server and to authenticate and verify
any messages it receives from the server. The client's key SHOULD any messages it receives from the server. The client's key SHOULD
be initially distributed to the client through some out-of-band be initially distributed to the client through some out-of-band
mechanism, and SHOULD be stored locally on the client for use in all mechanism, and SHOULD be stored locally on the client for use in all
authenticated DHCP messages. Once the client has been given its key, authenticated DHCP messages. Once the client has been given its key,
it SHOULD use that key for all transactions even if the client's it SHOULD use that key for all transactions even if the client's
configuration changes; e.g., if the client is assigned a new network configuration changes; e.g., if the client is assigned a new network
address. address.
Each DHCP server MUST know, or be able to obtain in a secure manner, Each DHCP server MUST know, or be able to obtain in a secure manner,
the keys for all authorized clients. If all clients use the same the keys for all authorized clients. If all clients use the same
key, clients can perform both entity and message authentication for key, clients can perform both entity and message authentication for
all messages received from servers. However, the sharing of keys all messages received from servers. However, the sharing of keys
is strongly discouraged as it allows for unauthorized clients to is strongly discouraged as it allows for unauthorized clients to
masquerade as authorized clients by obtaining a copy of the shared masquerade as authorized clients by obtaining a copy of the shared
key. To authenticate the identity of individual clients, each client key. To authenticate the identity of individual clients, each client
MUST be configured with a unique key. MUST be configured with a unique key.
19.6.5. Client considerations for delayed authentication protocol 21.6.5. Client considerations for delayed authentication protocol
19.6.5.1. Sending Solicit messages 21.6.5.1. Sending Solicit messages
When the client sends a Solicit message and wishes to use When the client sends a Solicit message and wishes to use
authentication, it includes an Authentication option with the desired authentication, it includes an Authentication option with the desired
protocol, algorithm, RDM and replay detection field as described protocol, algorithm, RDM and replay detection field as described
in section 19.6. The client does not include any authentication in section 21.6. The client does not include any authentication
information in the Authentication option. information in the Authentication option.
19.6.5.2. Receiving Advertise messages 21.6.5.2. Receiving Advertise messages
The client validates any Advertise messages containing an The client validates any Advertise messages containing an
Authentication option specifying the delayed authentication protocol Authentication option specifying the delayed authentication protocol
using the validation test described in section 19.6.3. using the validation test described in section 21.6.3.
Client behavior if no Advertise messages include authentication Client behavior if no Advertise messages include authentication
information or pass the validation test is controlled by local policy information or pass the validation test is controlled by local policy
on the client. According to client policy, the client MAY choose to on the client. According to client policy, the client MAY choose to
respond to a Advertise message that has not been authenticated. respond to a Advertise message that has not been authenticated.
The decision to set local policy to accept unauthenticated messages The decision to set local policy to accept unauthenticated messages
should be made with care. Accepting an unauthenticated Advertise should be made with care. Accepting an unauthenticated Advertise
message can make the client vulnerable to spoofing and other message can make the client vulnerable to spoofing and other
attacks. If local users are not explicitly informed that the client attacks. If local users are not explicitly informed that the client
skipping to change at page 52, line 46 skipping to change at page 57, line 7
A client MUST be configurable to discard unauthenticated messages, A client MUST be configurable to discard unauthenticated messages,
and SHOULD be configured by default to discard unauthenticated and SHOULD be configured by default to discard unauthenticated
messages. A client MAY choose to differentiate between Advertise messages. A client MAY choose to differentiate between Advertise
messages with no authentication information and Advertise messages messages with no authentication information and Advertise messages
that do not pass the validation test; for example, a client might that do not pass the validation test; for example, a client might
accept the former and discard the latter. If a client does accept an accept the former and discard the latter. If a client does accept an
unauthenticated message, the client SHOULD inform any local users and unauthenticated message, the client SHOULD inform any local users and
SHOULD log the event. SHOULD log the event.
19.6.5.3. Sending Request, Confirm, Renew, Rebind or Release messages 21.6.5.3. Sending Request, Confirm, Renew, Rebind, Decline or Release
messages
If the client authenticated the Advertise message through which the If the client authenticated the Advertise message through which the
client selected the server, the client MUST generate authentication client selected the server, the client MUST generate authentication
information for subsequent Request, Confirm, Renew, Rebind or Release information for subsequent Request, Confirm, Renew, Rebind or Release
messages sent to the server as described in section 19.6. When the messages sent to the server as described in section 21.6. When the
client sends a subsequent message, it MUST use the same secret used client sends a subsequent message, it MUST use the same secret used
by the server to generate the authentication information. by the server to generate the authentication information.
19.6.5.4. Receiving Reply messages 21.6.5.4. Sending Information-request messages
If the client has negotiated a secret with the server through a
previous message exchange, the client MUST use the same secret used
by the server to generate the authentication information. If the
client has not negotiated a secret with the server, the client MUST
use a secret that has been selected for the client through some
external mechanism.
21.6.5.5. Receiving Reply messages
If the client authenticated the Advertise it accepted, the client If the client authenticated the Advertise it accepted, the client
MUST validate the associated Reply message from the server. The MUST validate the associated Reply message from the server. The
client MUST discard the Reply if the message fails to pass validation client MUST discard the Reply if the message fails to pass validation
and MAY log the validation failure. If the Reply fails to pass and MAY log the validation failure. If the Reply fails to pass
validation, the client MUST restart the DHCP configuration process by validation, the client MUST restart the DHCP configuration process by
sending a Solicit message. The client MAY choose to remember which sending a Solicit message. The client MAY choose to remember which
server replied with a Reply message that failed to pass validation server replied with a Reply message that failed to pass validation
and discard subsequent messages from that server. and discard subsequent messages from that server.
If the client accepted an Advertise message that did not include If the client accepted an Advertise message that did not include
authentication information or did not pass the validation test, the authentication information or did not pass the validation test, the
client MAY accept an unauthenticated Reply message from the server. client MAY accept an unauthenticated Reply message from the server.
19.6.6. Server considerations for delayed authentication protocol 21.6.5.6. Receiving Reconfigure messages
19.6.6.1. Receiving Solicit messages and Sending Advertise messages The client MUST validate the Reconfigure message from the server.
The client MUST discard the Reconfigure if the message fails to pass
validation and MAY log the validation failure.
21.6.6. Server considerations for delayed authentication protocol
21.6.6.1. Receiving Solicit messages and Sending Advertise messages
The server selects a secret for the client and includes The server selects a secret for the client and includes
authentication information in the Advertise message returned to the authentication information in the Advertise message returned to the
client as specified in section 19.6. The server MUST record the client as specified in section 21.6. The server MUST record the
identifier of the secret selected for the client and use that same identifier of the secret selected for the client and use that same
secret for validating subsequent messages with the client. secret for validating subsequent messages with the client.
19.6.6.2. Receiving Request, Confirm, Renew, Rebind or Release messages 21.6.6.2. Receiving Request, Confirm, Renew, Rebind or Release messages
and Sending Reply messages and Sending Reply messages
The server uses the secret identified in the message and validates The server uses the secret identified in the message and validates
the message as specified in section 19.6.3. If the message fails to the message as specified in section 21.6.3. If the message fails to
pass validation or the server does not know the secret identified by pass validation or the server does not know the secret identified by
the 'secret ID' field, the server MUST discard the message and MAY the 'secret ID' field, the server MUST discard the message and MAY
choose to log the validation failure. choose to log the validation failure.
If the message passes the validation procedure, the server responds If the message passes the validation procedure, the server responds
to the specific message as described in section 16.2. The server to the specific message as described in section 18.2. The server
MUST include authentication information generated using the secret MUST include authentication information generated using the secret
identified in the received message as specified in section 19.6. identified in the received message as specified in section 21.6.
19.6.6.3. Sending Reconfigure-Init messages 21.6.6.3. Sending Reconfigure messages
The server MUST include authentication information in a The server MUST include authentication information in a Reconfigure
Reconfigure-Init message, generated as specified in section 19.6 message, generated as specified in section 21.6 using the secret the
using the secret the server initially selected for the client to server initially negotiated with the client to which the Reconfigure
which the Reconfigure-Init message is to be sent. message is to be sent.
20. DHCP options If the server has not previously negotiated a secret with the client,
the server MUST use a secret that has been selected for the client
through some external mechanism.
22. DHCP options
Options are used to carry additional information and parameters Options are used to carry additional information and parameters
in DHCP messages. Every option shares a common base format, as in DHCP messages. Every option shares a common base format, as
described in section 20.1. described in section 22.1. All values in options is represented in
network order.
This document describes the DHCP options defined as part of the base This document describes the DHCP options defined as part of the base
DHCP specification. Other options may be defined in the future in a DHCP specification. Other options may be defined in the future in a
separate document. separate document.
20.1. Format of DHCP options 22.1. Format of DHCP options
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len | | option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data | | option-data |
| (option-len octets) | | (option-len octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code An unsigned integer identifying the specific option option-code An unsigned integer identifying the specific option
type carried in this option. type carried in this option.
option-len An unsigned integer giving the length of the data in option-len An unsigned integer giving the length of the
this option in octets. option-data field in this option in octets.
option-data The data for the option; the format of this data option-data The data for the option; the format of this data
depends on the definition of the option. depends on the definition of the option.
20.2. DHCP unique identifier option DHCPv6 options are scoped by using encapsulation. Some options apply
generally to the client, some are specific to an IA, and some are
specific to the addresses within an IA. These latter two cases are
discussed in sections 22.3 and 22.4.
22.2. DHCP unique identifier option
The DHCP unique identifier option is used to carry a DUID. The format The DHCP unique identifier option is used to carry a DUID. The format
for the DUID is keyed to mark the type of identifier and is of for the DUID is keyed to mark the type of identifier and is of
variable length. The format of the DUID option is: variable length. The format of the DUID option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION DUID | option-len | | OPTION DUID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID type | DUID | | DUID type | DUID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
. DUID (cont.) . . DUID (cont.) .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20.3. Identity association option 22.3. Identity association option
The identity association option is used to carry an identity The identity association option is used to carry an identity
association, the parameters associated with the IA and the addresses association, the parameters associated with the IA and the addresses
assigned to the IA. assigned to the IA.
The format of the IA option is: The format of the IA option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 55, line 32 skipping to change at page 60, line 32
| T2 | | T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IA Status | | | IA Status | |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
. Options . . Options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_IA (TBD) option-code OPTION_IA (TBD)
option-len Variable; equal to 13 + number of bytes option-len See section 22.
required for ``options''
IAID The unique identifier for this IA; chosen by IAID The unique identifier for this IA.
the client
T1 The time at which the client contacts the T1 The time at which the client contacts the
server from which the addresses in the IA server from which the addresses in the IA
were obtained to extend the lifetimes of the were obtained to extend the lifetimes of the
addresses assigned to the IA. addresses assigned to the IA.
T2 The time at which the client contacts any T2 The time at which the client contacts any
available server to extend the lifetimes of available server to extend the lifetimes of
the addresses assigned to the IA. the addresses assigned to the IA.
IA status Status of the IA in this option. IA status Status of the IA in this option.
options Options associated with this IA options Options associated with this IA.
The Options field carries those options that are specific to this
IA. This includes all of the Address Options to carry the addresses The Options field encapsulates those options that are specific
associated with this IA. to this IA. For example, all of the Address Options carrying the
addresses associated with this IA are in the Options field.
Note that an IA has no explicit "lifetime" or "lease length" of Note that an IA has no explicit "lifetime" or "lease length" of
its own. When the lifetimes of all of the addresses in an IA have its own. When the lifetimes of all of the addresses in an IA have
expired, the IA can be considered as having expired. T1 and T2 expired, the IA can be considered as having expired. T1 and T2
are included to give servers explicit control over when a client are included to give servers explicit control over when a client
recontacts the server about a specific IA. recontacts the server about a specific IA.
20.4. IA Address option In a message sent by a client to a server, values in the T1 and
T2 fields indicate the client's preference for those parameters.
The client may send 0 if it has no preference for T1 and T2. In a
message sent by a server to a client, the client MUST use the values
in the T1 and T2 fields for the T1 and T2 parameters. The values in
the T1 and T2 fields are the number of seconds until T1 and T2.
The server MUST set the T1 and T2 times to values that will allow
the client to extend as appropriate the lifetimes of any addresses
in the IA. If the server does not intend for a client to extend the
lifetimes of a particular address in an IA, the server MAY set the
renewal time values to occur after the lifetimes on that address
expire.
T1 is the time at which the client SHOULD begin the lifetime
extension process by sending a Renew message to the server that
originally assigned the addresses to the IA. T2 is the time at which
the client SHOULD start sending a Rebind message to any server. A
client MAY begin the lifetime extension process prior to T1 if it
needs additional addresses for some reason.
T1 and T2 are specified as unsigned integers that specify the time
in seconds relative to the time at which the messages containing the
option is received.
22.4. IA Address option
The IA Address option is used to specify IPv6 addresses associated
with an IA. The IA Address option must be encapsulated in the
Options field of an Identity Association option. The Options field
encapsulates those options that are specific to this address.
The format of the IA Address option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAADDR | option-len | | OPTION_IAADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T| addr status | prefix length | | |T| addr status | prefix length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| IPv6 address | | IPv6 address |
| (16 octets) | | (16 octets) |
skipping to change at page 56, line 39 skipping to change at page 62, line 37
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid lifetime (cont.) | | | valid lifetime (cont.) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. . . .
. Options . . Options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_IADDR (TBD) option-code OPTION_IADDR (TBD)
option-len The number of bytes in the data area of this option option-len See section 22.
T When set to 1, indicates that this address is a T When set to 1, indicates that this address is a
"temporary address" [15]; when set to 0, the address "temporary address" [17]; when set to 0, the address
is not a temporary address. is not a temporary address.
The 'T' bit identifies the associated address as
a temporary address. If the server is configured
to assign temporary addresses to the client, the
server marks those temporary addresses with the 'T'
bit. The number of temporary addresses assigned to
the client and the lifetimes of those addresses is
determined by the administrative configuration of
the server. The 'T' bit only identifies an address
as a temporary address; identification of an address
as "temporary" has no implication on the lifetime of
the extensibility of the lifetime of the address.
addr status Status of this address in this IA. addr status Status of this address in this IA.
prefix length Prefix length for this address. prefix length Prefix length for this address.
IPv6 address An IPv6 address IPv6 address An IPv6 address
preferred lifetime The preferred lifetime for the IPv6 address in preferred lifetime The preferred lifetime for the IPv6 address in
the option. the option.
valid lifetime The valid lifetime for the IPv6 address in the valid lifetime The valid lifetime for the IPv6 address in the
skipping to change at page 57, line 19 skipping to change at page 63, line 4
prefix length Prefix length for this address. prefix length Prefix length for this address.
IPv6 address An IPv6 address IPv6 address An IPv6 address
preferred lifetime The preferred lifetime for the IPv6 address in preferred lifetime The preferred lifetime for the IPv6 address in
the option. the option.
valid lifetime The valid lifetime for the IPv6 address in the valid lifetime The valid lifetime for the IPv6 address in the
option option
options Options associated with this address options Options associated with this address
The IA Address option is used to specify IPv6 addresses associated In a message sent by a client to a server, values in the preferred
with an IA. It may only appear in an IA option. and valid lifetime fields indicate the client's preference for those
parameters. The client may send 0 if it has no preference for the
preferred and valid lifetimes. In a message sent by a server to a
client, the client MUST use the values in the preferred and valid
lifetime fields for the preferred and valid lifetimes. The values in
the preferred and valid lifetimes are the number of seconds remaining
in each lifetime.
The Options field carries those options that are specific to this One or more IA Address Options can appear anywhere in an IA option.
address.
20.5. Option request option 22.5. Requested Temporary Addresses (RTA) Option
The Requested Temporary Addresses (RTA) option is used by a client to
request a server to assign additional temporary addresses to an IA.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RTA | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| num-requested |
+-+-+-+-+-+-+-+-+
option-code OPTION_RTA (TBD)
option-len See section 22.
num-requested The number of additional temporary addresses the
client is requesting. This is an unsigned value.
This option MUST only be sent by a client and only in a Solicit,
Request, Renew, or Rebind message. It MUST only appear encapsulated
within an Identity association option. A client that does not need
any additional temporary addresses does not need to include this
option.
22.6. Option request option
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ORO | option-len | | OPTION_ORO | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| requested-option-code-1 | requested-option-code-2 | | requested-option-code-1 | requested-option-code-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_ORO (TBD) option-code OPTION_ORO (TBD)
option-len Variable; equal to twice the number of option codes option-len See section 22.
carried in this option.
option-data A list of the option codes for the options requested requested-option-code-n The option code for an option requested by
in this option. the client.
A client MAY include an Option Request option in a Solicit, Request, A client MAY include an Option Request option in a Solicit, Request,
Renew, Rebind or Confirm message to inform the server about options Renew, Rebind or Confirm message to inform the server about options
the client wants the server to send to the client. the client wants the server to send to the client.
20.6. Preference option 22.7. Preference option
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_PREFERENCE | option-len | | OPTION_PREFERENCE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pref value | | pref value |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
option-code OPTION_PREFERENCE (TBD) option-code OPTION_PREFERENCE (TBD)
option-len MUST be 1 option-len See section 22.
option-data The preference value for the server in this message. pref value The preference value for the server in this message.
A server MAY include a Preference option in an Advertise message to A server MAY include a Preference option in an Advertise message to
control the selection of a server by the client. See section 15.1.3 control the selection of a server by the client. See section 17.1.3
for the use of the Preference option by the client and the for the use of the Preference option by the client and the
interpretation of Preference option data value. interpretation of Preference option data value.
20.7. Elapsed Time 22.8. Elapsed Time
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ELAPSED_TIME | option_len | | OPTION_ELAPSED_TIME | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| elapsed time | | elapsed time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_ELAPSED_TIME (TBD) option-code OPTION_ELAPSED_TIME (TBD)
option-len MUST be 2 option-len See section 22.
option-data The amount of time since the client began its elapsed time The amount of time since the client began its
current DHCP transaction. This time is expressed in current DHCP transaction. This time is expressed in
hundredths of a second (10^-2 seconds). hundredths of a second (10^-2 seconds).
A client MAY include an Elapsed Time option in messages to indicate A client MAY include an Elapsed Time option in messages to indicate
how long the client has been trying to complete a DHCP transaction. how long the client has been trying to complete a DHCP transaction.
Servers MAY use the data value in this option as input to policy Servers and Relay Agents MAY use the data value in this option
controlling how a server responds to a client message. as input to policy controlling how a server responds to a client
message.
22.9. Client message option
20.8. Client message option
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CLIENT_MSG | option-len | | OPTION_CLIENT_MSG | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DHCP client message |
| | | |
. DHCP client message .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CLIENT_MSG (TBD) option-code OPTION_CLIENT_MSG (TBD)
option-len Variable; equal to the length of the forwarded DHCP option-len See section 22.
client message.
option-data The message received from the client; forwarded DHCP client message The message received from the client;
verbatim to the server. forwarded verbatim to the server.
A relay agent forwards a message from a client to a server as the A relay agent forwards a message from a client to a server as the
contents of a Client Message option in a Relay-forward message. contents of a Client Message option in a Relay-forward message.
20.9. Server message option 22.10. Server message option
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SERVER_MSG | option-len | | OPTION_SERVER_MSG | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DHCP server message |
| | | |
. DHCP server message .
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SERVER_MSG (TBD) option-code OPTION_SERVER_MSG (TBD)
option-len Variable; equal to the length of the forwarded DHCP option-len See section 22.
server message.
option-data The message received from the server; forwarded DHCP server message The message received from the server;
verbatim to the client. forwarded verbatim to the client.
A server sends a DHCP message to be forwarded to a client by a relay A server sends a DHCP message to be forwarded to a client by a relay
agent as the contents of a Server Message option in a Relay-reply agent as the contents of a Server Message option in a Relay-reply
message. message.
20.10. DSTM Global IPv4 Address Option 22.11. DSTM Global IPv4 Address Option
The DSTM Global IPv4 Address Option informs a client or server that The DSTM Global IPv4 Address Option informs a client or server that
the Identity Association Option (IA) following this option will the Identity Association Option (IA) encapsulated in this option
contain an IPv4-Mapped IPv6 Address [9] in the case of a Client contains or requests an IPv4-Mapped IPv6 Address [10], as used in the
receiving the option, or is a Request for an IPv4-Mapped IPv6 Address ``Dual Stack Transition Mechanism'' (DSTM) [3].
from a client in the case of a DHCPv6 Server receiving the option.
The option can also provide a set of IPv6 addresses to be used as the
Tunnel Endpoint (TEP) to encapsulate an IPv6 packet within IPv6.
This option can be used with the Request, Reply, and Reconfigure-Init 0 1 2 3
Messages for cases where a server wants to assign to clients 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
IPv4-Mapped IPv6 Addresses, thru the Option Request Option (ORO). +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DSTM | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_DSTM (TBD)
option-len See section 22.
options Options associated with DSTM.
One Identity Association Option MUST always be encapsulated within
the DSTM Global IPv4 Address Option options field and that Identity
Association MUST only be used for IPv4-Mapped IPv6 Addresses.
A DSTM Tunnel End Point Option MAY be encapsulated within the DSTM
Global IPv4 Address Option to specify one or more tunnel endpoints.
DISCUSSION:
By encapsulation the Identity Association Option within
the DSTM Global IPv4 Address Option, a server that does
not support the address type will simply ignore the entire
option and therefore not improperly allocate any addresses
to the Identity Association. This technique of using an
address typing option, SHOULD be used for other address
types that may be needed in the future.
22.12. DSTM Tunnel EndPoint Option
A DSTM Tunnel EndPoint Option can be used to provide a set of IPv6
addresses to be used as the Tunnel Endpoint (TEP) to encapsulate an
IPv6 packet within IPv6.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DSTM | option-length | | OPTION_DSTM_TEP | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel End Point (TEP) | | Tunnel End Point (TEP) |
| (If Present) |
| (16 octets) | | (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option code OPTION_DSTM (TBD) option-code OPTION_DSTM_TEP (TBD)
option length Variable: 0 or multiple of 16 option-len See section 22.
tunnel end point IPv6 Address or addresses if Present tunnel end point IPv6 address or addresses.
A DSTM IPv4 Global Address Option MUST only apply to the IA following A DSTM Tunnel EndPoint Option MUST NOT be used except when
this option. encapsulated in a DSTM Global IPv4 Address option.
20.11. Authentication option 22.13. Authentication option
The Authentication option carries authentication information to The Authentication option carries authentication information to
authenticate the identity and contents of DHCP messages. The use of authenticate the identity and contents of DHCP messages. The use of
the Authentication option is described in section 19. the Authentication option is described in section 21.
The format of the Authentication option is: The format of the Authentication option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_AUTH | option-length | | OPTION_AUTH | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | Algorithm | RDM | Replay detect.| | Protocol | Algorithm | RDM | Replay detect.|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection (64 bits) | | Replay Detection (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay cont. | Auth. Info | | Replay cont. | Auth. Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Authentication Information | | Authentication Information |
| | | |
skipping to change at page 61, line 4 skipping to change at page 68, line 22
| Protocol | Algorithm | RDM | Replay detect.| | Protocol | Algorithm | RDM | Replay detect.|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay Detection (64 bits) | | Replay Detection (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replay cont. | Auth. Info | | Replay cont. | Auth. Info |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Authentication Information | | Authentication Information |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_AUTH (TBD) option-code OPTION_AUTH (TBD)
option-length Variable option-len See section 22.
protocol The authentication protocol used in protocol The authentication protocol used in
this authentication option this authentication option
algorithm The algorithm used in the algorithm The algorithm used in the
authentication protocol authentication protocol
RDM The replay detection method used in RDM The replay detection method used in
this authentication option this authentication option
Replay detection The replay detection information for Replay detection The replay detection information for
the RDM the RDM
Authentication information The authentication information, Authentication information The authentication information,
as specified by the protocol and as specified by the protocol and
algorithm used in this authentication algorithm used in this authentication
option option
20.12. Server unicast option 22.14. Server unicast option
This option is used by a server to send to a client to inform The server MAY send this option to a client to indicate to the client
the client it MAY send a Request, Renew, Release, and Decline by that is allowed to unicast messages to the server. When a client
unicasting directly to the server instead of the All_DHCPv6_Agents receives this option, where permissible, the client MAY send messages
Multicast address as an optimization, when the client as an address to the server using the IPv6 address that the server specifies in the
of sufficient scope to reach the server. server address field in this option.
Details about when the client may send messages to the server using
unicast are in section 18.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_UNICAST | option-length | | OPTION_UNICAST | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_UNICAST (TBD) option-code OPTION_UNICAST (TBD)
option-length 0 option-len See section 22.
This option only applies to the server address that sends this to the
client.
20.13. Domain Search Option 22.15. Domain Search Option
This option provides a list of domain names a client can use to This option provides a list of domain names a client can use to
resolve DNS names. resolve DNS names.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DOMAIN_SEARCH_LIST | option-length | | OPTION_DOMAIN_SEARCH_LIST | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Search List | | Domain Search List |
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_DOMAIN_SEARCH_LIST (TBD) option-code OPTION_DOMAIN_SEARCH_LIST (TBD)
option-length variable option-len See section 22.
Domain Search List The DNS domain search list the client Domain Search List The DNS domain search list the client
should use to resolve names. should use to resolve names.
So that the search list may be encoded compactly and uniformly, The domain search list is stored in the option according to
search strings in the search list are concatenated and encoded using section 10.
the technique described in section 3.1 of [13].
For use in this specification, the compression pointer (see section
4.1.4 of [13]) refers to the offset within the SearchString portion
of the option.
20.14. Domain Name Server Option 22.16. Domain Name Server Option
This option provides a list of Domain Name System [13] that a client This option provides a list of one or more IP addresses of DNS
name resolver can use to access DNS services. There must be at least servers to which a client's DNS resolver MAY send DNS [14] queries.
1 server listed in this option. The DNS servers are listed in the order of preference for use by the
client resolver.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_DNS_SERVERS | option_length | | OPTION_DNS_SERVERS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| DNS server (IP address) | | DNS server (IP address) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| DNS server (IP address) | | DNS server (IP address) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_DNS_SERVERS (11) option-code OPTION_DNS_SERVERS (11)
option-length variable
option-len See section 22.
DNS server IPv6 address of a DNS name server for the DNS server IPv6 address of a DNS name server for the
client to use. The DNS servers are listed in client to use.
the order of preference for use by the client
resolver.
20.15. Status Code Option 22.17. Status Code Option
This option returns indications of status not related to a specific This option returns a status indication related to the DHCP message
option. in which it appears.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_STATUS_CODE | option-length | | OPTION_STATUS_CODE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| status-code | status-message | | status-code | status-message |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_STATUS_CODE (TBD) option-code OPTION_STATUS_CODE (TBD)
option-len See section 22.
option-length variable
status-code The numeric code for the status encoded in status-code The numeric code for the status encoded in
this option. The status codes are defined in this option. The status codes are defined in
section 7.4. section 7.4.
status-message A UTF-8 encoded text string, which MUST NOT status-message A UTF-8 encoded text string, which MUST NOT
be null-terminated. be null-terminated.
20.16. Circuit-ID Option 22.18. Circuit-ID Option
This option provides a mechanism through which a relay agent can The relay agent MAY send the Circuit-ID option to identify the
identify the network attachment point through which a message was circuit-id on which the client message was received.
received from a DHCP client.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CIRCUIT_ID | option_length | | OPTION_CIRCUIT_ID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Circuit-ID | | Circuit-ID |
. . . .
. . . .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CIRCUIT_ID (TBD) option-code OPTION_CIRCUIT_ID (TBD)
option-length variable option-len See section 22.
Circuit-ID An opaque value of arbitrary length; this Circuit-ID An opaque value of arbitrary length generated
value must uniquely identify one of the by the relay agent.
network attachments used by the relay agent
20.17. User Class Option The server MUST copy the Circuit-ID option from the Relay-Forward
message into the Relay-Reply message the server sends to the relay
agent in response to the Relay-Forward message. This option MUST NOT
appear in any message except a Relay-Forward or Relay-Reply message.
22.19. User Class Option
This option is used by a client to identify the type or category of This option is used by a client to identify the type or category of
user or applications it represents. The information contained in user or applications it represents. The information contained in
this option is an opaque field that represents the user class of this option is an opaque field that represents the user class of
which the client is a member. Based on this class, a DHCP server which the client is a member. The user class information carried in
selects the appropriate address pool to assign an address to the this option MUST be configurable on the client.
client and the appropriate configuration parameters.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_USER_CLASS | option-len | | OPTION_USER_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| user class data | | user class data |
| . . . | | . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code TBD option-code TBD
option-len Variable; If n user classes are carried option-len See section 22.
by the option, the length of the option
option-len = sum of each of the user class
lengths + 2*n.
option-data The user classes carried by the client. user class data The user classes carried by the client.
The user class option may contain one or more instances of user class The user class option MUST contain one or more instances of user
data. Each instance of the user class data is formatted as follows: class data. Each instance of the user class data is formatted as
follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
| user class1 len | user1 class data | | user class len | user class data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
The user class length is two octets long and specifies the length of The user class len is two octets long and specifies the length of the
the opaque user class data in network byte order. opaque user class data in network order.
Servers may interpret the meanings of multiple class specifications Servers can interpret the meanings of multiple class specifications
in an implementation dependent or configuration dependent manner, in an implementation dependent or configuration dependent manner,
and so the use of multiple classes by a DHCP client should be based and so the use of multiple classes by a DHCP client should be based
on the specific server implementation and configuration which will on the specific server implementation and configuration which will
be used to process that User class option. Servers not equipped to be used to process that User class option. Servers not equipped to
interpret the user class information sent by a client MUST ignore it interpret the user class information sent by a client MUST ignore it
(although it may be reported). (although it may be reported).
20.18. Vendor Class Option 22.20. Vendor Class Option
This option is used by clients and servers to exchange vendor- This option is used by clients and servers to exchange
specific information. The definition of this information is vendor vendor-specific information. The definition of this information
specific. The vendor is indicated in the vendor class identifier is vendor specific. The vendor is indicated in the vendor
option. Servers not equipped to interpret the vendor-specific class identifier option. Servers not equipped to interpret
information sent by a client MUST ignore it (although it may be the vendor-specific information sent by a client MUST ignore it
reported). Clients which do not receive desired vendor-specific (although it may be reported). Clients which do not receive desired
information SHOULD make an attempt to operate without it, although vendor-specific information SHOULD make an attempt to operate without
they may do so(and announce they are doing so) in a degraded mode. it, although they may do so (and announce they are doing so) in a
degraded mode.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_VENDOR_CLASS | option-len | | OPTION_VENDOR_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| vendor-id |
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data | | option-data |
| . . . | . .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code TBD option-code TBD
option-len Variable option-len See section 22.
option-data The information is an opaque object of vendor-id A domain name belonging to the vendor used to
option-len octets, presumably interpreted identify the vendor that defined this vendor
by vendor-specific code on the clients and class option.
servers
If a vendor potentially encodes more than one item of information option-data An opaque object of option-len octets,
in this option, then the vendor SHOULD encode the option using presumably interpreted by vendor-specific
"Encapsulated vendor-specific options". code on the clients and servers
The Encapsulated vendor-specific options field SHOULD be encoded as a The vendor-id must adhere to the rules in section 10.
sequence of code/length/value fields of identical syntax to the DHCP
options field.
When encapsulated vendor-specific extensions are used, each of the The Encapsulated vendor-specific options field MUST be encoded as
encapsulated options is formatted as follows. a sequence of code/length/value fields of identical format to the
DHCP options field. Each of the encapsulated options is formatted as
follows.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| opt_code | opt_len | | opt-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data | | option-data |
| . . . | | . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
opt_code The code for the encapsulated option
opt_len The length of the encapsulated option opt-code The code for the encapsulated option
option-len See section 22.
option-data The data area for the encapsulated option option-data The data area for the encapsulated option
21. Security Considerations 22.21. SIP Servers Domain Name List
Section 19 describes a threat model and an option that provides an This option specifies a list of fully-qualified domain names
to be used by the SIP client to locate a SIP server (see
<draft-ietf-sip-srv-02.txt> [22] for more details.
The option MAY contain multiple domain names, but these SHOULD refer
to different SRV records, rather than different A records. Domain
names SHOULD be listed in order of preference.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIP_SERVER_D | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SIP Server Domain Name List |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SIP_SERVER_D (TBD)
option-len See section 22.
SIP Server Domain List The list of SIP servers the client
should use (see section 10 for
encoding details).
22.22. SIP Servers IPv6 Address List
This option specifies a list of IPv6 addresses indicating
SIP outbound proxy servers available to the client (see
<draft-ietf-sip-srv-02.txt> [22] for more details. Servers SHOULD be
listed in order of preference.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SIP_SERVER_A | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SIP Server (IP address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SIP Server (IP address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SIP_SERVER_A (TBD)
option-len See section 22.
SIP Server IPv6 address of a SIP server for the client to use.
The servers are listed in the order of preference for
use by the client.
23. Security Considerations
Section 21 describes a threat model and an option that provides an
authentication framework to defend against that threat model. authentication framework to defend against that threat model.
22. Year 2000 considerations 24. Year 2000 considerations
Since all times are relative to the current time of the transaction, Since all times are relative to the current time of the transaction,
there is no problem within the DHCPv6 protocol related to any there is no problem within the DHCPv6 protocol related to any
hardcoded dates or two-digit representation of the current year. hardcoded dates or two-digit representation of the current year.
23. IANA Considerations 25. IANA Considerations
This document defines several new name spaces associated with DHCPv6 This document defines several new name spaces associated with DHCPv6
and DHCPv6 options. IANA is requested to manage the allocation of and DHCPv6 options. IANA is requested to manage the allocation of
values from these name spaces, which are described in the remainder values from these name spaces, which are described in the remainder
of this section. These name spaces are all to be managed separately of this section. These name spaces are all to be managed separately
from the name spaces defined for DHCPv4 [7, 2]. from the name spaces defined for DHCPv4 [8, 2].
New values in each of these name spaces should be approved by the New values in each of these name spaces should be approved by the
process of IETF consensus [14]. process of IETF consensus [16].
23.1. Multicast addresses 25.1. Multicast addresses
Section 7.1 defines the following multicast addresses, which have Section 7.1 defines the following multicast addresses, which have
been assigned by IANA for use by DHCPv6: been assigned by IANA for use by DHCPv6:
All_DHCP_Agents address: FF02::1:2 All_DHCP_Agents address: FF02::1:2
All_DHCP_Servers address: FF05::1:3 All_DHCP_Servers address: FF05::1:3
IANA is requested to manage definition of additional multicast IANA is requested to manage definition of additional multicast
addresses in the future. addresses in the future.
23.2. DHCPv6 message types 25.2. DHCPv6 message types
IANA is requested to record the message types defined in section 7.3. IANA is requested to record the message types defined in section 7.3.
IANA is requested to manage definition of additional message types in IANA is requested to manage definition of additional message types in
the future. the future.
23.3. DUID 25.3. DUID
IANA is requested to record the DUID types defined in section 10.1. IANA is requested to record the DUID types defined in section 11.1.
IANA is requested to manage definition of additional DUID types in IANA is requested to manage definition of additional DUID types in
the future. the future.
23.4. DHCPv6 options 25.4. DHCPv6 options
IANA is requested to assign option-codes to the options defined IANA is requested to assign option-codes to the options defined
in section 20.1. IANA is requested to manage the definition of in section 22.1. IANA is requested to manage the definition of
additional DHCPv6 option-codes in the future. additional DHCPv6 option-codes in the future.
23.5. Status codes 25.5. Status codes
IANA is requested to record the status codes defined in section 7.4. IANA is requested to record the status codes defined in section 7.4.
IANA is requested to manage the definition of additional status codes IANA is requested to manage the definition of additional status codes
in the future. in the future.
23.6. Authentication option 25.6. Authentication option
Section 19 defines three new name spaces associated with the Section 21 defines three new name spaces associated with the
Authentication Option (section 20.11), which are to be created and Authentication Option (section 22.13), which are to be created and
maintained by IANA: Protocol, Algorithm and RDM. maintained by IANA: Protocol, Algorithm and RDM.
Initial values assigned from the Protocol name space are 0 (for the Initial values assigned from the Protocol name space are 0 (for the
configuration token Protocol in section 19.5) and 1 (for the delayed configuration token Protocol in section 21.5) and 1 (for the delayed
authentication Protocol in section 19.6). Additional protocols may authentication Protocol in section 21.6). Additional protocols may
be defined in the future. be defined in the future.
The Algorithm name space is specific to individual Protocols. That The Algorithm name space is specific to individual Protocols. That
is, each Protocol has its own Algorithm name space. The guidelines is, each Protocol has its own Algorithm name space. The guidelines
for assigning Algorithm name space values for a particular protocol for assigning Algorithm name space values for a particular protocol
should be specified along with the definition of a new Protocol. should be specified along with the definition of a new Protocol.
For the configuration token Protocol, the Algorithm field MUST be For the configuration token Protocol, the Algorithm field MUST be
0, as described in section 19.5. For the delayed authentication 0, as described in section 21.5. For the delayed authentication
Protocol, the Algorithm value 1 is assigned to the HMAC-MD5 Protocol, the Algorithm value 1 is assigned to the HMAC-MD5
generating function as defined in section 19.6. Additional generating function as defined in section 21.6. Additional
algorithms for the delayed authentication protocol may be defined in algorithms for the delayed authentication protocol may be defined in
the future. the future.
The initial value of 0 from the RDM name space is assigned to the The initial value of 0 from the RDM name space is assigned to the
use of a monotonically increasing value as defined in section 19.4. use of a monotonically increasing value as defined in section 21.4.
Additional replay detection methods may be defined in the future. Additional replay detection methods may be defined in the future.
24. Acknowledgments 26. Acknowledgments
Thanks to the DHC Working Group for their time and input into the Thanks to the DHC Working Group for their time and input into
specification. Ralph Droms and Thomas Narten have had a major the specification. In particular, thanks also for the consistent
role in shaping the continued improvement of the protocol by their input, ideas, and review by (in alphabetical order) Brian Carpenter,
careful reviews. Many thanks to Matt Crawford, Erik Nordmark, Gerald Matt Crawford, Francis Dupont, Ted Lemon, Josh Littlefield, Gerald
Maguire, and Mike Carney for their studied review as part of the Maguire, Jack McCann, Thomas Narten, Erik Nordmark, Yakov Rekhter,
Last Call process. Thanks also for the consistent input, ideas, and Mark Stapp, Matt Thomas, Sue Thomson, Bernie Volz and Phil Wells.
review by (in alphabetical order) Brian Carpenter, Francis DuPont,
Ted Lemon, Jack McCann, Yakov Rekhter, Matt Thomas, Sue Thomson,
Bernie Volz and Phil Wells.
Thanks to Steve Deering and Bob Hinden, who have consistently Thanks to Steve Deering and Bob Hinden, who have consistently
taken the time to discuss the more complex parts of the IPv6 taken the time to discuss the more complex parts of the IPv6
specifications. specifications.
Bill Arbaugh reviewed the authentication mechanism described in Bill Arbaugh reviewed the authentication mechanism described in
section 19. section 21.
The Domain Search option described in section 20.13 is based on the The Domain Search option described in section 22.15 is based on the
DHCPv4 domain search option, [1], and was reviewed by Bernard Aboba. DHCPv4 domain search option, [1], and was reviewed by Bernard Aboba.
And, thanks to Steve Deering for pointing out at IETF 51 in London
that the DHCPv6 specification has (at least currently) the highest
revision number of any Internet Draft.
A. Full Copyright Statement A. Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved. Copyright (C) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, are included on all such copies and derivative works. However,
skipping to change at page 68, line 50 skipping to change at page 78, line 5
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
B. Appearance of Options in Message Types
The following table indicates with a "*" the options are allowed in
each DHCP message type:
DUID IA RTA ORO Pref Time Client Server DSTM DSTM
Forw. Forw. Addr Tunn
Solicit * * * *
Advert. * * * * * * *
Request * * * *
Confirm * * * *
Renew * * * *
Rebind * * * *
Decline * * * *
Release * * * *
Reply * * * * * * *
Reconf. * *
Inform. * *
R-forw. * *
R-repl. * *
Auth Server Domain Domain Status Circ. User Vendor
Unica. Search Server Code ID Class Class
Solicit * * *
Advert. * * *
Request * * *
Confirm * * *
Renew * * *
Rebind * * *
Decline * * * *
Release * * * *
Reply * * * * *
Reconf. *
Inform. * * *
R-forw. * *
R-repl. * *
C. Appearance of Options in the Options Field of DHCP Messages
The following table indicates with a "*" where options can appear in
the options field or encapsulated in other options:
Option IA IAADDR RTA DSTM Client Server
Field Addr Forw. Forw.
Client msg. * *
Server msg. * *
DUID *
IA * *
IAADDR *
RTA *
ORO *
Pref *
Time *
Client Forw. *
Server Forw. *
DSTM Addr. *
DSTM Tunnel *
Authentic. *
Server Uni. *
Dom. Srch. *
Dom. Server *
Status Cod. * * *
Circ. ID * *
User Class *
Vend. Class *
References References
[1] B. Aboba. DHCP Domain Search Option. Internet Draft, Internet [1] B. Aboba. DHCP Domain Search Option. Internet Draft, Internet
Engineering Task Force, December 2000. Work in progress. Engineering Task Force, December 2000. Work in progress.
[2] S. Alexander and R. Droms. DHCP Options and BOOTP Vendor [2] S. Alexander and R. Droms. DHCP Options and BOOTP Vendor
Extensions, March 1997. RFC 2132. Extensions, March 1997. RFC 2132.
[3] S. Bradner. Key words for use in RFCs to Indicate Requirement [3] J. Bound, L. Toutain, F. Dupont, O. Medina, A. Hossam, and
A. Durand. Dual Stack Transition Mechanism (DSTM). Internet
Draft, Internet Engineering Task Force, November 2001. Work in
progress.
[4] S. Bradner. Key words for use in RFCs to Indicate Requirement
Levels, March 1997. RFC 2119. Levels, March 1997. RFC 2119.
[4] S. Bradner and A. Mankin. The Recommendation for the IP Next [5] S. Bradner and A. Mankin. The Recommendation for the IP Next
Generation Protocol, January 1995. RFC 1752. Generation Protocol, January 1995. RFC 1752.
[5] W.J. Croft and J. Gilmore. Bootstrap Protocol, September 1985. [6] W.J. Croft and J. Gilmore. Bootstrap Protocol, September 1985.
RFC 951. RFC 951.
[6] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6) [7] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6)
Specification, December 1998. RFC 2460. Specification, December 1998. RFC 2460.
[7] R. Droms. Dynamic Host Configuration Protocol, March 1997. RFC [8] R. Droms. Dynamic Host Configuration Protocol, March 1997. RFC
2131. 2131.
[8] R. Droms and W. Arbaugh. Authentication for DHCP Messages. [9] R. Droms, Editor, W. Arbaugh, and Editor. Authentication for
Internet Draft, Internet Engineering Task Force, January 2001. DHCP Messages, June 2001. RFC 3118.
Work in progress.
[9] R. Hinden and S. Deering. IP Version 6 Addressing Architecture, [10] R. Hinden and S. Deering. IP Version 6 Addressing Architecture,
July 1998. RFC 2373. July 1998. RFC 2373.
[10] S. Kent and R. Atkinson. Security Architecture for the Internet [11] S. Kent and R. Atkinson. Security Architecture for the Internet
Protocol, November 1998. RFC 2401. Protocol, November 1998. RFC 2401.
[11] H. Krawczyk, M. Bellare, and R. Canetti. HMAC: Keyed-Hashing [12] H. Krawczyk, M. Bellare, and R. Canetti. HMAC: Keyed-Hashing
for Message Authentication, February 1997. RFC 2104. for Message Authentication, February 1997. RFC 2104.
[12] David L. Mills. Network Time Protocol (Version 3) [13] David L. Mills. Network Time Protocol (Version 3)
Specification, Implementation, March 1992. RFC 1305. Specification, Implementation, March 1992. RFC 1305.
[13] P.V. Mockapetris. Domain names - implementation and [14] P.V. Mockapetris. Domain names - concepts and facilities,
November 1987. RFC 1034.
[15] P.V. Mockapetris. Domain names - implementation and
specification, November 1987. RFC 1035. specification, November 1987. RFC 1035.
[14] T. Narten and H. Alvestrand. Guidelines for Writing an IANA [16] T. Narten and H. Alvestrand. Guidelines for Writing an IANA
Considerations Section in RFCs, October 1998. RFC 2434. Considerations Section in RFCs, October 1998. RFC 2434.
[15] T. Narten and R. Draves. Privacy Extensions for Stateless [17] T. Narten and R. Draves. Privacy Extensions for Stateless
Address Autoconfiguration in IPv6, January 2001. RFC 3041. Address Autoconfiguration in IPv6, January 2001. RFC 3041.
[16] T. Narten, E. Nordmark, and W. Simpson. Neighbor Discovery for [18] T. Narten, E. Nordmark, and W. Simpson. Neighbor Discovery for
IP Version 6 (IPv6), December 1998. RFC 2461. IP Version 6 (IPv6), December 1998. RFC 2461.
[17] D.C. Plummer. Ethernet Address Resolution Protocol: Or [19] D.C. Plummer. Ethernet Address Resolution Protocol: Or
converting network protocol addresses to 48.bit Ethernet address converting network protocol addresses to 48.bit Ethernet address
for transmission on Ethernet hardware, November 1982. RFC 826. for transmission on Ethernet hardware, November 1982. RFC 826.
[18] J. Postel. User Datagram Protocol, August 1980. RFC 768. [20] J. Postel. User Datagram Protocol, August 1980. RFC 768.
[19] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC [21] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC
1321. 1321.
[20] S. Thomson and T. Narten. IPv6 Stateless Address [22] H. Schulzrinne and J. Rosenberg. SIP: Session Initiation
Protocol -- Locating SIP Servers. Internet Draft, Internet
Engineering Task Force, March 2001. Work in progress.
[23] S. Thomson and T. Narten. IPv6 Stateless Address
Autoconfiguration, December 1998. RFC 2462. Autoconfiguration, December 1998. RFC 2462.
[21] P. Vixie, Ed., S. Thomson, Y. Rekhter, and J. Bound. Dynamic [24] P. Vixie, Ed., S. Thomson, Y. Rekhter, and J. Bound. Dynamic
Updates in the Domain Name System (DNS UPDATE), April 1997. RFC Updates in the Domain Name System (DNS UPDATE), April 1997. RFC
2136. 2136.
Chair's Address Chair's Address
The working group can be contacted via the current chair: The working group can be contacted via the current chair:
Ralph Droms Ralph Droms
Cisco Systems Cisco Systems
300 Apollo Drive 300 Apollo Drive
 End of changes. 

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