draft-ietf-dhc-dhcpv6-20.txt   draft-ietf-dhc-dhcpv6-21.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-dhcpv6-19.txt Sun Microsystems, Inc Obsoletes: draft-ietf-dhc-dhcpv6-20.txt Sun Microsystems, Inc
C. Perkins C. Perkins
Nokia Research Center Nokia Research Center
R. Droms(ed.) R. Droms(ed.)
Cisco Systems Cisco Systems
15 Oct 2001 21 Nov 2001
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
draft-ietf-dhc-dhcpv6-20.txt draft-ietf-dhc-dhcpv6-21.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 58 skipping to change at page 1, line 58
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 1 2. Requirements 2
3. Background 1 3. Background 2
4. Design Goals 2 4. Design Goals 3
5. Non-Goals 3 5. Non-Goals 3
6. Terminology 3 6. Terminology 4
6.1. IPv6 Terminology . . . . . . . . . . . . . . . . . . . . 3 6.1. IPv6 Terminology . . . . . . . . . . . . . . . . . . . . 4
6.2. DHCP Terminology . . . . . . . . . . . . . . . . . . . . 5 6.2. DHCP Terminology . . . . . . . . . . . . . . . . . . . . 5
7. DHCP Constants 6 7. DHCP Constants 6
7.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 6 7.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 7
7.2. UDP ports . . . . . . . . . . . . . . . . . . . . . . . . 6 7.2. UDP ports . . . . . . . . . . . . . . . . . . . . . . . . 7
7.3. DHCP message types . . . . . . . . . . . . . . . . . . . 7 7.3. DHCP message types . . . . . . . . . . . . . . . . . . . 7
7.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 8 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 . . . . . . . . . . 9
7.5. Configuration Variables . . . . . . . . . . . . . . . . . 10 7.5. Configuration Variables . . . . . . . . . . . . . . . . . 10
8. Message Formats 10 8. Message Formats 10
8.1. DHCP Solicit Message Format . . . . . . . . . . . . . . . 11 8.1. DHCP Solicit Message Format . . . . . . . . . . . . . . . 11
8.2. DHCP Advertise Message Format . . . . . . . . . . . . . . 11 8.2. DHCP Advertise Message Format . . . . . . . . . . . . . . 11
8.3. DHCP Request Message Format . . . . . . . . . . . . . . . 12 8.3. DHCP Request Message Format . . . . . . . . . . . . . . . 12
8.4. DHCP Confirm Message Format . . . . . . . . . . . . . . . 12 8.4. DHCP Confirm Message Format . . . . . . . . . . . . . . . 12
8.5. DHCP Renew Message Format . . . . . . . . . . . . . . . . 12 8.5. DHCP Renew Message Format . . . . . . . . . . . . . . . . 12
8.6. DHCP Rebind Message Format . . . . . . . . . . . . . . . 12 8.6. DHCP Rebind Message Format . . . . . . . . . . . . . . . 12
8.7. DHCP Reply Message Format . . . . . . . . . . . . . . . . 13 8.7. DHCP Reply Message Format . . . . . . . . . . . . . . . . 13
8.8. DHCP Release Message Format . . . . . . . . . . . . . . . 13 8.8. DHCP Release Message Format . . . . . . . . . . . . . . . 13
8.9. DHCP Decline Message Format . . . . . . . . . . . . . . . 13 8.9. DHCP Decline Message Format . . . . . . . . . . . . . . . 13
8.10. DHCP Reconfigure-init Message Format . . . . . . . . . . 13 8.10. DHCP Reconfigure-init Message Format . . . . . . . . . . 13
8.11. Inform Message Format . . . . . . . . . . . . . . . . . . 14
9. Relay messages 14 9. Relay messages 14
9.1. Relay-forward message . . . . . . . . . . . . . . . . . . 14 9.1. Relay-forward message . . . . . . . . . . . . . . . . . . 14
9.2. Relay-reply message . . . . . . . . . . . . . . . . . . . 15 9.2. Relay-reply message . . . . . . . . . . . . . . . . . . . 15
10. DHCP unique identifier (DUID) 15 10. DHCP unique identifier (DUID) 15
10.1. DUID contents . . . . . . . . . . . . . . . . . . . . . . 15 10.1. DUID contents . . . . . . . . . . . . . . . . . . . . . . 16
10.2. DUID based on link-layer address plus time . . . . . . . 16 10.2. DUID based on link-layer address plus time . . . . . . . 16
10.3. Vendor-assigned unique ID. . . . . . . . . . . . . . . . 17 10.3. Vendor-assigned unique ID. . . . . . . . . . . . . . . . 17
10.4. Link-layer address . . . . . . . . . . . . . . . . . . . 17 10.4. Link-layer address . . . . . . . . . . . . . . . . . . . 18
11. Identity association 18 11. Identity association 18
12. Selecting addresses for assignment to an IA 18 12. Selecting addresses for assignment to an IA 19
13. Reliability of Client Initiated Message Exchanges 19 13. Reliability of Client Initiated Message Exchanges 19
14. Message validation 20 14. Message validation 21
14.1. Use of Transaction-ID field . . . . . . . . . . . . . . . 21 14.1. Use of Transaction-ID field . . . . . . . . . . . . . . . 21
14.2. Solicit message . . . . . . . . . . . . . . . . . . . . . 21 14.2. Solicit message . . . . . . . . . . . . . . . . . . . . . 21
14.3. Advertise message . . . . . . . . . . . . . . . . . . . . 21 14.3. Advertise message . . . . . . . . . . . . . . . . . . . . 21
14.4. Request message . . . . . . . . . . . . . . . . . . . . . 21 14.4. Request message . . . . . . . . . . . . . . . . . . . . . 22
14.5. Confirm message . . . . . . . . . . . . . . . . . . . . . 21 14.5. Confirm message . . . . . . . . . . . . . . . . . . . . . 22
14.6. Renew message . . . . . . . . . . . . . . . . . . . . . . 21 14.6. Renew message . . . . . . . . . . . . . . . . . . . . . . 22
14.7. Rebind message . . . . . . . . . . . . . . . . . . . . . 22 14.7. Rebind message . . . . . . . . . . . . . . . . . . . . . 22
14.8. Decline messages . . . . . . . . . . . . . . . . . . . . 22 14.8. Decline messages . . . . . . . . . . . . . . . . . . . . 22
14.9. Release message . . . . . . . . . . . . . . . . . . . . . 22 14.9. Release message . . . . . . . . . . . . . . . . . . . . . 23
14.10. Reply message . . . . . . . . . . . . . . . . . . . . . . 22 14.10. Reply message . . . . . . . . . . . . . . . . . . . . . . 23
14.11. Reconfigure-init message . . . . . . . . . . . . . . . . 22 14.11. Reconfigure-init message . . . . . . . . . . . . . . . . 23
14.12. Relay-forward message . . . . . . . . . . . . . . . . . . 23 14.12. Inform message . . . . . . . . . . . . . . . . . . . . . 23
14.13. Relay-reply message . . . . . . . . . . . . . . . . . . . 23 14.13. Relay-forward message . . . . . . . . . . . . . . . . . . 23
14.14. Relay-reply message . . . . . . . . . . . . . . . . . . . 23
15. DHCP Server Solicitation 23 15. DHCP Server Solicitation 24
15.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 23 15.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 24
15.1.1. Creation of Solicit messages . . . . . . . . . . 23 15.1.1. Creation of Solicit messages . . . . . . . . . . 24
15.1.2. Transmission of Solicit Messages . . . . . . . . 23 15.1.2. Transmission of Solicit Messages . . . . . . . . 24
15.1.3. Receipt of Advertise messages . . . . . . . . . . 25 15.1.3. Receipt of Advertise messages . . . . . . . . . . 25
15.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 25 15.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 26
15.2.1. Receipt of Solicit messages . . . . . . . . . . . 25 15.2.1. Receipt of Solicit messages . . . . . . . . . . . 26
15.2.2. Creation and transmission of Advertise messages . 26 15.2.2. Creation and transmission of Advertise messages . 26
16. DHCP Client-Initiated Configuration Exchange 26 16. DHCP Client-Initiated Configuration Exchange 27
16.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 27 16.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 27
16.1.1. Creation and transmission of Request messages . . 27 16.1.1. Creation and transmission of Request messages . . 28
16.1.2. Creation and transmission of Confirm messages . . 28 16.1.2. Creation and transmission of Confirm messages . . 29
16.1.3. Creation and transmission of Renew messages . . . 29 16.1.3. Creation and transmission of Renew messages . . . 30
16.1.4. Creation and transmission of Rebind messages . . 31 16.1.4. Creation and transmission of Rebind messages . . 31
16.1.5. Receipt of Reply message in response to a Request, 16.1.5. Creation and Transmission of Inform messages . . 33
Confirm, Renew or Rebind message . . . . . 32 16.1.6. Receipt of Reply message in response to a Request,
16.1.6. Creation and transmission of Release messages . . 33 Confirm, Renew, Rebind or Inform message . 33
16.1.7. Receipt of Reply message in response to a Release 16.1.7. Creation and transmission of Release messages . . 35
message . . . . . . . . . . . . . . . . . 35 16.1.8. Receipt of Reply message in response to a Release
16.1.8. Creation and transmission of Decline messages . . 35
16.1.9. Receipt of Reply message in response to a Decline
message . . . . . . . . . . . . . . . . . 36 message . . . . . . . . . . . . . . . . . 36
16.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 36 16.1.9. Creation and transmission of Decline messages . . 36
16.2.1. Receipt of Request messages . . . . . . . . . . . 36 16.1.10. Receipt of Reply message in response to a Decline
16.2.2. Receipt of Confirm messages . . . . . . . . . . . 37 message . . . . . . . . . . . . . . . . . 37
16.2.3. Receipt of Renew messages . . . . . . . . . . . . 38 16.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 38
16.2.4. Receipt of Rebind messages . . . . . . . . . . . 39 16.2.1. Receipt of Request messages . . . . . . . . . . . 38
16.2.5. Receipt of Release messages . . . . . . . . . . . 40 16.2.2. Receipt of Confirm messages . . . . . . . . . . . 39
16.2.6. Receipt of Decline messages . . . . . . . . . . . 40 16.2.3. Receipt of Renew messages . . . . . . . . . . . . 39
16.2.7. Sending of Reply messages . . . . . . . . . . . . 41 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 41 17. DHCP Server-Initiated Configuration Exchange 43
17.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 41 17.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 43
17.1.1. Creation and transmission of Reconfigure-init 17.1.1. Creation and transmission of Reconfigure-init
messages . . . . . . . . . . . . . . . . . 41 messages . . . . . . . . . . . . . . . . . 43
17.1.2. Time out and retransmission of Reconfigure-init 17.1.2. Time out and retransmission of Reconfigure-init
messages . . . . . . . . . . . . . . . . . 42 messages . . . . . . . . . . . . . . . . . 44
17.1.3. Receipt of Request messages . . . . . . . . . . . 42 17.1.3. Receipt of Rebind messages . . . . . . . . . . . 44
17.2. Client Behavior . . . . . . . . . . . . . . . . . . . . . 43 17.2. Client Behavior . . . . . . . . . . . . . . . . . . . . . 45
17.2.1. Receipt of Reconfigure-init messages . . . . . . 43 17.2.1. Receipt of Reconfigure-init messages . . . . . . 45
17.2.2. Creation and sending of Request messages . . . . 44 17.2.2. Creation and sending of Rebind messages . . . . . 46
17.2.3. Time out and retransmission of Request messages . 44 17.2.3. Time out and retransmission of Rebind messages . 46
17.2.4. Receipt of Reply messages . . . . . . . . . . . . 44 17.2.4. Receipt of Reply messages . . . . . . . . . . . . 46
18. Relay Behavior 44 18. Relay Behavior 46
18.1. Relaying of client messages . . . . . . . . . . . . . . . 45 18.1. Relaying of client messages . . . . . . . . . . . . . . . 46
18.2. Relaying of server messages . . . . . . . . . . . . . . . 45 18.2. Relaying of server messages . . . . . . . . . . . . . . . 47
19. Authentication of DHCP messages 45 19. Authentication of DHCP messages 47
19.1. DHCP threat model . . . . . . . . . . . . . . . . . . . . 46 19.1. DHCP threat model . . . . . . . . . . . . . . . . . . . . 48
19.2. Security of messages sent between servers and relay agents 46 19.2. Security of messages sent between servers and relay agents 48
19.3. Summary of DHCP authentication . . . . . . . . . . . . . 46 19.3. Summary of DHCP authentication . . . . . . . . . . . . . 48
19.4. Replay detection . . . . . . . . . . . . . . . . . . . . 47 19.4. Replay detection . . . . . . . . . . . . . . . . . . . . 49
19.5. Configuration token protocol . . . . . . . . . . . . . . 47 19.5. Configuration token protocol . . . . . . . . . . . . . . 49
19.6. Delayed authentication protocol . . . . . . . . . . . . . 48 19.6. Delayed authentication protocol . . . . . . . . . . . . . 49
19.6.1. Management issues in the delayed authentication 19.6.1. Management issues in the delayed authentication
protocol . . . . . . . . . . . . . . . . . 48 protocol . . . . . . . . . . . . . . . . . 50
19.6.2. Use of the Authentication option in the delayed 19.6.2. Use of the Authentication option in the delayed
authentication protocol . . . . . . . . . 48 authentication protocol . . . . . . . . . 50
19.6.3. Message validation . . . . . . . . . . . . . . . 49 19.6.3. Message validation . . . . . . . . . . . . . . . 51
19.6.4. Key utilization . . . . . . . . . . . . . . . . . 49 19.6.4. Key utilization . . . . . . . . . . . . . . . . . 51
19.6.5. Client considerations for delayed authentication 19.6.5. Client considerations for delayed authentication
protocol . . . . . . . . . . . . . . . . . 50 protocol . . . . . . . . . . . . . . . . . 52
19.6.6. Server considerations for delayed authentication 19.6.6. Server considerations for delayed authentication
protocol . . . . . . . . . . . . . . . . . 51 protocol . . . . . . . . . . . . . . . . . 53
20. DHCP options 52
20.1. Format of DHCP options . . . . . . . . . . . . . . . . . 52
20.2. DHCP unique identifier option . . . . . . . . . . . . . . 53
20.3. Identity association option . . . . . . . . . . . . . . . 53
20.4. Option request option . . . . . . . . . . . . . . . . . . 56
20.5. Preference option . . . . . . . . . . . . . . . . . . . . 56
20.6. Elapsed Time . . . . . . . . . . . . . . . . . . . . . . 57
20.7. Client message option . . . . . . . . . . . . . . . . . . 57
20.8. Server message option . . . . . . . . . . . . . . . . . . 58
20.9. DSTM Global IPv4 Address Option . . . . . . . . . . . . . 58
20.10. Authentication option . . . . . . . . . . . . . . . . . . 59
20.11. Server unicast option . . . . . . . . . . . . . . . . . . 60
20.12. Domain Search Option . . . . . . . . . . . . . . . . . . 60
20.13. Domain Name Server Option . . . . . . . . . . . . . . . . 61
20.14. Status Code Option . . . . . . . . . . . . . . . . . . . 61
20.15. Circuit-ID Option . . . . . . . . . . . . . . . . . . . . 62
20.16. User Class Option . . . . . . . . . . . . . . . . . . . . 63
20.17. Vendor Class Option . . . . . . . . . . . . . . . . . . . 63
21. Security Considerations 65 20. DHCP options 54
20.1. Format of DHCP options . . . . . . . . . . . . . . . . . 54
20.2. DHCP unique identifier option . . . . . . . . . . . . . . 54
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
22. Year 2000 considerations 65 21. Security Considerations 66
23. IANA Considerations 65 22. Year 2000 considerations 66
23.1. Multicast addresses . . . . . . . . . . . . . . . . . . . 65
23.2. DHCPv6 message types . . . . . . . . . . . . . . . . . . 65
23.3. DUID . . . . . . . . . . . . . . . . . . . . . . . . . . 65
23.4. DHCPv6 options . . . . . . . . . . . . . . . . . . . . . 66
23.5. Status codes . . . . . . . . . . . . . . . . . . . . . . 66
23.6. Authentication option . . . . . . . . . . . . . . . . . . 66
24. Acknowledgments 66 23. IANA Considerations 66
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
A. Comparison between DHCPv4 and DHCPv6 67 24. Acknowledgments 67
B. Full Copyright Statement 69 A. Full Copyright Statement 68
References 69 References 68
Chair's Address 71 Chair's Address 70
Authors' Addresses 71 Authors' Addresses 70
1. Introduction 1. Introduction
This document describes DHCP for IPv6 (DHCP), a UDP [18] This document describes DHCP for IPv6 (DHCP), a UDP [18]
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" [20]. DHCP is a stateful counterpart to
stateless autoconfiguration. Note that both stateful and stateless stateless autoconfiguration. Note that both stateful and stateless
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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 each 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 find DHCP for IPv6 Those readers familiar with DHCP for IPv4 [7] will find DHCP for IPv6
provides a superset of features, and benefits from the additional provides a superset of features, and benefits from the additional
features of IPv6 and freedom from the constraints of backward features of IPv6 and freedom from the constraints of backward
compatibility with BOOTP [5]. For more information about the compatibility with BOOTP [5].
differences between DHCP for IPv6 and DHCP for IPv4, see Appendix A.
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 [3].
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
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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 is the IPv6 Specification [6], the IPv6 Addressing
Architecture [9], IPv6 Stateless Address Autoconfiguration [20], IPv6 Architecture [9], IPv6 Stateless Address Autoconfiguration [20], IPv6
Neighbor Discovery Processing [16], and Dynamic Updates to DNS [22]. Neighbor Discovery Processing [16], and Dynamic Updates to DNS [21].
These specifications enable DHCP to build upon the IPv6 work to These specifications enable DHCP to build upon the IPv6 work to
provide both robust stateful autoconfiguration and autoregistration provide both robust stateful autoconfiguration and autoregistration
of DNS Host Names. of DNS Host Names.
The IPv6 Addressing Architecture specification [9] defines the The IPv6 Addressing Architecture specification [9] 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
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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 [16] is the node discovery protocol in IPv6
which replaces and enhances functions of ARP [17]. To understand which replaces and enhances functions of ARP [17]. 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 [22] is a specification that supports the Dynamic Updates to DNS [21] 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
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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 valid. still valid.
RENEW (5) The Renew message is used by clients to RENEW (5) The Renew message is used by clients to
obtain the addresses assigned to an IA and update the addresses assigned to an IA and
the lifetimes for those addresses, as well as the lifetimes for those addresses, as well as
the current configuration parameters assigned the current configuration parameters assigned
by the server to the client. A client sends by the server to the client. A client sends
a Renew message to the server that originally a Renew message to the server that originally
assigned the IA when the lease on an IA is populated the IA at time T1.
about to expire.
REBIND (6) The Rebind message is used by clients to REBIND (6) The Rebind message is used by clients to
obtain the addresses assigned to an IA and extend the lifetimes of addresses assigned to
the lifetimes for those addresses, as well as an IA, as well as the current configuration
the current configuration parameters assigned parameters assigned by the server to the
by the server to the client. A clients client. A client sends a Rebind message to
sends a Rebind message to all available DHCP all available DHCP servers at time T2 only
servers when the lease on an IA is about to after the client has been unable to contact
expire. the server that originally populated the IA
with a Rebind message.
REPLY (7) The Reply message is used by servers REPLY (7) The Reply message is used by servers
responding to Request, Confirm, Renew, responding to Request, Confirm, Renew,
Rebind, Release and Decline messages. In the Rebind, Release and Decline messages. In the
case of responding to a Request, Confirm, case of responding to a Request, Confirm,
Renew or Rebind message, the Reply contains Renew or Rebind message, the Reply contains
configuration parameters destined for the configuration parameters 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
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connected. connected.
RECONFIG-INIT (10) The Reconfigure-init message is sent by RECONFIG-INIT (10) The Reconfigure-init message is sent by
server(s) to inform client(s) that the server(s) to inform client(s) that the
server(s) has new or updated configuration server(s) has new or updated configuration
parameters, and that the client(s) are to parameters, and that the client(s) are to
initiate a Request/Reply transaction with the initiate a Request/Reply transaction with the
server(s) in order to receive the updated server(s) in order to receive the updated
information. information.
RELAY-FORW (11) The Relay-forward message is used by relays INFORM (11) The Inform message is sent by clients to
request configuration parameters without the
assignment of any IP addresses to the client.
RELAY-FORW (12) The Relay-forward message is used by relays
to forward client messages to servers. The to forward client messages to servers. The
client message is encapsulated in an option client message is encapsulated in an option
in the Relay-forward message. in the Relay-forward message.
RELAY-REPL (12) The Relay-reply message is used by servers RELAY-REPL (13) The Relay-reply message is used by servers
to send messages to clients through a relay. to send messages to clients through a relay.
The server encapsulates the client message The server encapsulates the client message
as an option in the Relay-reply message, as an option in the Relay-reply message,
which the relay extracts and forwards to the which 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
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SOL_TIMEOUT 500 msecs Initial Solicit timeout SOL_TIMEOUT 500 msecs Initial Solicit timeout
SOL_MAX_RT 30 secs Max Solicit timeout value SOL_MAX_RT 30 secs Max Solicit timeout value
REQ_TIMEOUT 250 msecs Initial Request timeout REQ_TIMEOUT 250 msecs Initial Request timeout
REQ_MAX_RT 30 secs Max Request timeout value REQ_MAX_RT 30 secs Max Request timeout value
REQ_MAX_RC 10 Max Request retry attempts REQ_MAX_RC 10 Max Request retry attempts
CNF_TIMEOUT 250 msecs Initial Confirm timeout CNF_TIMEOUT 250 msecs Initial Confirm timeout
CNF_MAX_RT 1 sec Max Confirm timeout CNF_MAX_RT 1 sec Max Confirm timeout
CNF_MAX_RD 10 secs Max Confirm duration CNF_MAX_RD 10 secs Max Confirm duration
REN_TIMEOUT 10 sec Initial Renew timeout REN_TIMEOUT 10 sec Initial Renew timeout
REN_MAX_RT 600 secs Max Renew timeout value REN_MAX_RT 600 secs Max Renew timeout value
REB_TIMEOUT 10 sec Initial Rebind timeout REB_TIMEOUT 10 secs Initial Rebind timeout
REB_MAX_RT 600 secs Max Rebind timeout value REB_MAX_RT 600 secs Max Rebind timeout value
INF_TIMEOUT 500 ms Initial Inform timeout
INF_MAX_RT 30 secs Max Inform timeout value
REL_TIMEOUT 250 msecs Initial Release timeout REL_TIMEOUT 250 msecs Initial Release timeout
REL_MAX_RT 1 sec Max Release timeout REL_MAX_RT 1 sec Max Release timeout
REL_MAX_RC 5 MAX Release/Decline attempts REL_MAX_RC 5 MAX Release/Decline attempts
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
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options See section 20. options See section 20.
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 the 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 20.
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
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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. The address must server-address The IP address of the server.
have sufficient scope to be reachable from the
client.
options See section 20. options See section 20.
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.
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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-init 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-init 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 20.
8.11. DHCP Inform Message Format
msg-type INFORM
transaction-ID An unsigned integer generated by the server used
to identify this Inform message.
server-address MUST be zero.
options See section 20.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | | | msg-type | |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
| link-prefix | | link-address |
| | | |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | | | | |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
| client-return-address | | client-return-address |
| | | |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | | | | |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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-prefix 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 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 "Client message option"; options MUST include a "Client message option";
see section 20.7; MAY include other see section 20.8; 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-forward message.
msg-type RELAY-REPL msg-type RELAY-REPL
link-prefix 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 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 20.8; MAY include other see section 20.9; MAY include other
options options
10. DHCP unique identifier (DUID) 10. 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 20.2 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 must be unique
across all DHCP clients, and it must also be consistent for the same across all DHCP clients, and it must also be consistent for the same
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.
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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 11. 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 IA and a client can identify, group and manage IPv6 addresses. Each
consists of an IAID and a list of associated IPv6 addresses (the list IA consists of an IAID and associated configuration information. A
may be empty). A client associates an IA with one of its interfaces client associates an IA with one of its interfaces and uses the IA to
and uses the IA to obtain IPv6 addresses for that interface from a obtain configuration information for that interface from a server.
server.
The configuration information in an IA consists of one or more IPv6
addresses and other parameters. The parameters are specified as DHCP
options within the IA, and are associated with the addresses in the
IA and the interface to which the IA belongs. Other parameters that
are not associated with a particular interface may be specified in
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,
as defined in RFC2462 [20]. The lifetimes are transmitted from the
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.
An address whose valid lifetime has expired MAY be discarded from the
IA.
See section 20.3 for the representation of an IA in a DHCP message. See section 20.3 for the representation of an IA in a DHCP message.
12. Selecting addresses for assignment to an IA 12. 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:
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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
message was received is a link-local address, then the client message was received is a link-local address, then the client
is on the same link to which the interface over which the is on the same link to which the interface over which the
message was received is attached message was received 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
message was received is not a link-local address, then the message was received is not a link-local address, then the
client is on the link identified by the source address in the client is on the link identified by the source address in the
IP datagram IP datagram
* If the server receives the message from a forwarding relay * If the server receives the message from a forwarding relay
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-prefix 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 13. Reliability of Client Initiated Message Exchanges
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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 if the client
attempts to transmit the original message more than MRD seconds. attempts to transmit the original message more than 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 paragraph 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 14. 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 19.6.5.2.
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14.11. Reconfigure-init message 14.11. Reconfigure-init message
Servers and relay agents MUST discard any received Reconfigure-init Servers and relay agents MUST discard any received Reconfigure-init
messages. messages.
Clients MUST discard any Reconfigure-init messages that do not Clients MUST discard any Reconfigure-init messages that do not
contain an authentication option or that fail the authentication contain an authentication option or that fail the authentication
performed by the client. performed by the client.
14.12. Relay-forward message 14.12. Inform message
Clients MUST discard any received Inform messages.
Relay agents MUST discard any Inform messages received through port
546.
14.13. Relay-forward message
Clients MUST discard any received Relay-forward messages. Clients MUST discard any received Relay-forward messages.
14.13. Relay-reply message 14.14. 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 15. DHCP Server Solicitation
This section describes how a client locates servers. This section describes how a client locates servers that will assign
addresses to IAs belonging to the client.
The client is responsible for creating IAs and requesting that a
server assign configuration information, including IPv6 addresses,
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
describing the IA. Servers that can assign configuration information
to the IA respond to the client with an Advertise message. The
client then initiates a configuration exchange as described in
section 16.
15.1. Client Behavior 15.1. 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 15.1.1. 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 options for any IAs to which it server. The client MUST include IA options for any IAs to which
wants the server to assign addresses. The client MAY choose not to it wants the server to assign addresses. The client MAY include
include any IAs in the Solicit message if it does not need to request addresses in the IAs as a hint to the server about addresses for
that any addresses be assigned. The client MAY include addresses in which the client may have a preference. The client MAY include
the IAs as a hint to the server about addresses for which the client an Option Request Option in the Solicit message. The client MUST
may have a preference. The client MAY include an Option Request NOT include any other options except those specifically allowed as
Option in the Solicit message. The client MUST NOT include any other defined by specific options.
options except those specifically allowed as defined by specific
options.
15.1.2. Transmission of Solicit Messages 15.1.2. 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
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 13, using the
following parameters: following parameters:
IRT SOL_TIMEOUT IRT SOL_TIMEOUT
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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. 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 20.5). Any Solicit that does not include a Preference (section 20.6). 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 more 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 MAY choose to restart the reconfiguration process after
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MAY add a Preference option to carry the preference value for the MAY add a Preference option to carry the preference value for the
Advertise message. 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. If the Solicit message from the the Solicit message from the client. The server MAY include some or
client included no IAs, the server MUST not include any IAs in the all of the IA options from the client in the Advertise message.
Advertise message. If the server will not assign any addresses to
IAs in a subsequent Request from the client, the server MAY choose to If the server will not assign any addresses to IAs in a subsequent
send an Advertise message to the client that includes only a status Request from the client, the server MAY either send an Advertise
code option with the status code set to AddrUnavail and a status message to the client that includes only a status code option with
message for the user. the status code set to AddrUnavail and a status message for the user
or discard the Advertise 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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16. DHCP Client-Initiated Configuration Exchange 16. 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 16.1. Client Behavior
A client will use Request, Confirm, Renew and Rebind messages to A client will use Request, Confirm, Renew, Rebind and Inform messages
acquire and confirm the validity of configuration information. The to acquire and confirm the validity of configuration information.
client uses the server address information from previous Advertise The client uses the server address information and information about
message(s) for use in constructing Request and Renew message(s). IAs from previous Advertise messages for use in constructing Request
Note that a client may request configuration information from one or messages. Note that a client may request configuration information
more servers at any time. from one or more servers at any time.
16.1.1. Creation and transmission of Request messages 16.1.1. Creation and transmission of Request messages
If the client is using stateful address configuration and needs The client uses a Request message to populate IAs with addresses
either an initial set of addresses or additional addresses, it and obtain other configuration information. The client includes
MUST send a Request message to obtain new addresses and other one or more IA options in the Request message, with addresses and
configuration information. The client includes one or more IAs in information about the IAs that were obtained from the server in a
the Request message, to which the server assigns new addresses. The previous Advertise message. The server then returns addresses and
server then returns IA(s) to the client in a Reply message. other information about the IAs to the client in IA options in a
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
"transaction-ID" field. "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 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 be empty. If the client is not requesting that the included IA MUST include the addresses received by the client in a
server assign it any addresses, the client omits the IA option. previous Advertise message.
If the client has a source address that can be used by the server If the client has a source address of sufficient scope that can be
as a return address and the client has received a Client Unicast used by the server as a return address and the client has received
option (section 20.11) from the server, the client SHOULD unicast a Client Unicast option (section 20.12) from the server, the client
the Request message to the server. Otherwise, the client MUST send SHOULD unicast the Request message to the server. Otherwise, the
the Request message to the All_DHCP_Agents multicast address. The client MUST send the Request message to the All_DHCP_Agents multicast
client MUST use an address assigned to the interface for which the address. The client MUST use an address assigned to the interface
client is interested in obtaining configuration information as the for which the client is interested in obtaining configuration
source address in the IP header of the datagram carrying the Request information as the source address in the IP header of the datagram
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
relay agent options in all messages sent by the client. The relay agent options in all messages sent by the client. The
server should enable the use of unicast only when relay server should enable the use of unicast only when relay
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
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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 cells o The client using a wireless technology changes links
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 (if the client is requesting that the server confirm more IA options. The client MUST include the addresses the client
the validity of some IPv6 addresses). If the client does include currently has associated with those IAs.
any IA options, it MUST include the list of addresses the client
currently has associated with that IA.
The client sends the Confirm message to the All_DHCP_Agents The client sends the Confirm 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 Confirm message. 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
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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 13 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 16.1.3. Creation and transmission of Renew messages
IPv6 addresses assigned to a client through an IA use the same To extend the valid and preferred lifetimes associated with
preferred and valid lifetimes as IPv6 addresses obtained through addresses, the client sends a Renew message to the server containing
stateless address autoconfiguration. The server assigns preferred an "IA option" for the IA and its associated addresses. The server
and valid lifetimes to the IPv6 addresses it assigns to an IA. To determines new lifetimes for the addresses in the IA according to the
extend those lifetimes, the client sends a Renew message to the administrative configuration of the server. The server may also add
server containing an "IA option" for the IA and its associated new addresses to the IA. The server may remove addresses from the IA
addresses. The server determines new lifetimes for the addresses in by setting the preferred and valid lifetimes of those addresses to
the IA according to the administrative configuration of the server. zero.
The server may also add new addresses to the IA. The server may
remove addresses from the IA by setting the preferred and valid
lifetimes of those addresses to zero.
The server controls the time at which the client contacts the server The server controls the time at which the client contacts the server
to extend the lifetimes on assigned addresses through the T1 and to extend the lifetimes on assigned addresses through the T1 and T2
T2 parameters assigned to an IA. If the server does not assign an parameters assigned to an IA.
explicit value to T1 or T2 for an IA, T1 defaults to 0.5 times the
shortest preferred lifetime of any address assigned to the IA and
T2 defaults to 0.875 times the shortest preferred lifetime of any
address assigned to the IA.
At time T1 for an IA, the client initiates a Renew/Reply message At time T1 for an IA, the client initiates a Renew/Reply message
exchange to extend the lifetimes on any addresses in the IA. The exchange to extend the lifetimes on any addresses in the IA. The
client includes an IA option with all addresses currently assigned to client includes an IA option with all addresses currently assigned to
the IA in its Renew message. the IA in its Renew message.
The client sets the "msg-type" field to RENEW. The client generates a The client sets the "msg-type" field to RENEW. The client generates a
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 lease on some IAs; note that the client may check the status of the lifetimes of the addresses assigned to those IAs; note that the
other configuration parameters without asking for lease extensions). client may check the status of other configuration parameters without
If the client does include any IA options, it MUST include the list asking for lifetime extensions). If the client does include any IA
of addresses the client currently has associated with that IA. options, it MUST include the list of addresses the client currently
has associated with that IA.
If the client has a source address that can be used by the server as If the client has a source address of sufficient scope that can be
a return address and the client has received a Client Unicast option used by the server as a return address and the client has received
(section 20.11) from the server, the client SHOULD unicast the Renew a Client Unicast option (section 20.12) from the server, the client
message to the server. Otherwise, the client sends the Renew message SHOULD unicast the Renew message to the server. Otherwise, the
to the All_DHCP_Agents multicast address. The client MUST use an client sends the Renew message to the All_DHCP_Agents multicast
address assigned to the interface for which the client is interested address. The client MUST use an address assigned to the interface
in obtaining configuration information as the source address in the for which the client is interested in obtaining configuration
IP header of the datagram carrying the Renew message. information as the source address in the IP header of the datagram
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 13, using the
following parameters: following parameters:
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16.1.4. Creation and transmission of Rebind messages 16.1.4. 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 inserts this value in the "transaction-ID" field. a transaction ID and 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, 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 the more IA options. If the client does include any IA options (if
client is requesting that the server extend the lease on some IAs; the client is requesting that the server extend the lifetimes of
note that the client may check the status of other configuration addresses assigned to those IAs; note that the client may check
parameters without asking for lease extensions), it MUST include the the status of other configuration parameters without asking for
list of addresses the client currently has associated with that IA. 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
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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 13, 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 13 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 lease for the IA expires (see section 11), at which time the when the lifetimes on the addresses assigned to the IA expire (see
client has several alternative actions to choose from: section 11), at which time the client has several alternative actions
to choose from:
- When the lease on the IA expires, 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 server
- Some addresses in the IA may have lifetimes that extend beyond - The client may choose to use a Solicit message to locate a new
the lease of the IA, so the client may choose to continue to use DHCP server and send a Request for the expired IA to the new
those addresses; once all of the addresses have expired, the server
client may choose to locate a new DHCP 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. Receipt of Reply message in response to a Request, Confirm, 16.1.5. Creation and Transmission of Inform messages
Renew or Rebind message
The client uses an Inform message to obtain configuration information
without having addresses assigned to it. The client sets the
"msg-type" field to INFORM. The client generates a transaction ID and
inserts this value in the "transaction-ID" field.
The client sets the "server-address" field to 0.
The client MUST include a DUID option to identify itself to the
server. The client adds any appropriate options such as an ORO to
indicate to the server what configuration information the client is
interested in obtaining.
The client MUST use an IPv6 address assigned to the interface for
which the client is interested in obtaining configuration information
as the source address in the IP header of the datagram carrying the
Rebind message.
If the client has an IPv6 address of sufficient scope, the
client MAY choose to send the Inform message to the Allmulticast
address. Otherwise, the client MUST send the Inform message to the
All_DHCP_Agents multicast address.
The Inform message MUST be transmitted on the link that the interface
for which configuration information is being obtained is attached
to. The client SHOULD send the message through that interface. 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
are attached to the same link.
The client transmits the message according to section 13, using the
following parameters:
IRT INF_TIMEOUT
MRT INF_MAX_RT
MRC 0
MRD 0
16.1.6. Receipt of Reply message in response to a Request, Confirm,
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, Confirm, Renew or Rebind message, the client extracts the Request, Confirm, Renew or Rebind 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 [20] on each of
the addresses in any IAs it receives in the Reply message. If any of the addresses in any IAs it receives in the Reply message. If any of
the addresses are found to be in use on the link, the client sends a the addresses are found to be in use on the link, the client sends a
Decline message to the server as described in section 16.1.8. Decline message to the server as described in section 16.1.9.
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.
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 Reply message. The client adds any new addresses from 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
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 20.
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 status in an IA from the
server for a Confirm message the client can assume it needs to send a server 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 lease for 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.
When the client receives a RenwNoMatch status in an IA from the When the client receives a RenwNoMatch status in an IA from the
server for a Renew message the client can assume it needs to send a server for a Renew 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 an AddrUnavail status in an IA from the When the client receives an AddrUnavail status in an IA from the
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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.
16.1.6. Creation and transmission of Release messages 16.1.7. 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 appropriate "status" field in the MUST be included in the IAs. The client continues to use any other
options MUST be set to indicate the reason for the release. addresses in the IA. The appropriate "status" field in the options
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 that can be used by the server If the client has a source address of sufficient scope that can be
as a return address and the client has received a Client Unicast used by the server as a return address and the client has received
option (section 20.11) from the server, the client SHOULD unicast the a Client Unicast option (section 20.12) from the server, the client
Release message to the server. Otherwise, the client MUST send the SHOULD unicast the Release message to the server. Otherwise, the
Release message to the All_DHCP_Agents multicast address. The client client MUST send the Release message to the All_DHCP_Agents multicast
MUST use an address for the interface to which the IAs in the Release address. The client MUST use an address for the interface to which
message are assigned as the source address for the Release message. the IAs in the Release message are assigned as the source address for
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
server should enable the use of unicast only when relay server MUST NOT enable the use of unicast for a client when
agent options will not be used. relay agent options are required for that client.
If the Release message is multicast, it MUST be transmitted on the If the Release 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.
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
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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
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 lease assigned to the IA will be reclaimed by the server when the lifetime
associated with it expires. of the address expires.
16.1.7. Receipt of Reply message in response to a Release message 16.1.8. 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, and SHOULD return the successful status to Release event successful.
the application layer, if an application initiated the release.
16.1.8. Creation and transmission of Decline messages 16.1.9. 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 released declining in the "options" field. The addresses to be declined MUST
MUST be included in the IAs. The appropriate "status" field in the be included in the IAs. The client continues to use other addresses
options MUST be set to indicate the reason for declining the address. in the IAs. The appropriate "status" field in the options MUST be
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 that can be used by the server If the client has a source address of sufficient scope that can be
as a return address and the client has received a Client Unicast used by the server as a return address and the client has received
option (section 20.11) from the server, the client SHOULD unicast the a Client Unicast option (section 20.12) from the server, the client
Decline message to the server. Otherwise, the client MUST send the SHOULD unicast the Decline message to the server. Otherwise, the
Decline message to the All_DHCP_Agents multicast address. The client client MUST send the Decline message to the All_DHCP_Agents multicast
MUST use an IPv6 address for the interface to which the IAs in the address. The client MUST use an IPv6 address for the interface to
Release message are assigned as the source address for the Decline which the IAs in the Decline message are assigned as the source
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 should enable the use of unicast only when relay server MUST NOT enable the use of unicast for a client when
agent options will not be used. 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 13, using the
following parameters: following parameters:
skipping to change at page 36, line 19 skipping to change at page 37, line 48
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.
16.1.9. Receipt of Reply message in response to a Decline message 16.1.10. 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 16.2. 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 16.2.1. 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
client is requesting the configuration of a new IA by the server.
The server MUST take the IA from the client and associate a binding
for that client in an implementation-specific manner within the
configuration parameter database for DHCP clients managed by the
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
message containing the following values: message containing the following values:
msg-type REPLY msg-type REPLY
transaction-ID The transaction-ID from the Request message. transaction-ID The transaction-ID from the Request 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.
When the server receives a Request and IA option is included the
client is requesting the configuration of a new IA by the server.
The server MUST take the IA from the client and associate a binding
for that client in an implementation-specific manner within the
configuration parameter database for DHCP clients managed by the
server.
If the server finds that the prefix on one or more IP addresses in If the server finds that the prefix on one or more IP addresses in
any IA in the message fro the client is not a valid prefix for the any IA in the message from the client is not a valid prefix for the
link to which the client is connected, the server MUST return the IA link to which the client is connected, the server MUST return the IA
to the client with the status field set to NoPrefixMatch. to the client with the status field set to NoPrefixMatch.
If the server cannot provide addresses to the client it SHOULD If the server cannot assign any addresses to any of the IAs in
send back an empty IA to the client with the status field set to the message from the client, the server SHOULD include the IAs in
AddrUnavail. the Reply message with the status field set to AddrUnavail and no
addresses in the IA.
If the server can provide addresses to the client it MUST send back For any IAs to which the server can assign addresses, server includes
the IA to the client with all fields entered and a status of Success, the IA with addresses and other configuration parameters a status of
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 16.2.2. Receipt of Confirm messages
Upon the receipt of a valid Confirm message from a client the server
can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field.
The server then constructs a Reply message and sends it to the
client.
The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply
message containing the following values:
msg-type REPLY
transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface
through which the server received the message
from the client.
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
can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field.
If the server cannot determine if the information in the Confirm If the server cannot determine if the information in the Confirm
message is valid or invalid, the server MUST NOT send a reply to the message is valid or invalid, the server MUST NOT send a reply to the
client. For example, if the server does not have a binding for the client. For example, if the server does not have a binding for the
client, but the configuration information in the Confirm message client, but the configuration information in the Confirm message
appears valid, the server does not reply. appears valid, the server does not reply.
If the server finds that the information for the client does not If the server finds that the information for the client does not
match what is in the binding for that client or the configuration match what is in the binding for that client or the configuration
information is not valid, the server sends a Reply message containing information is not valid, the server sends a Reply message containing
a Status Code option with the value ConfNoMatch. a Status Code option with the value ConfNoMatch.
If the server finds that the information for the client does match If the server finds that the information for the client does match
the information in the binding for that client, and the configuration the information in the binding for that client, and the configuration
information is still valid, the server sends a Reply message information is still valid, the server sends a Reply message
containing a Status Code option with the value Success. containing a Status Code option with the value Success.
The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply
message containing the following values:
msg-type REPLY
transaction-ID The transaction-ID from the Confirm message.
server address One of the IP addresses assigned to the interface
through which the server received the message
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 16.2.3. 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.
The server then constructs a Reply message and sends it to the When the server receives a Renew and IA option from a client it
client. SHOULD locate the clients binding and verify the information in the
IA from the client matches the information stored for that client.
If the server cannot find a client entry for this IA the server
SHOULD return an IA containing no addresses with status set to
NoBinding.
If the server finds that the addresses in the IA for the client
do not match the client binding the server should return an IA
containing no addresses with status set to RenwNoMatch.
If the server cannot Renew addresses for the client it SHOULD send
back an IA containing no addresses to the client with the status
field set to AddrUnavail.
If the server finds the addresses in the IA for the client then the
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
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 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 Confirm message. transaction-ID The transaction-ID from the Renew 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.
When the server receives a Renew and IA option from a client it 16.2.4. Receipt of Rebind messages
Upon the receipt of a valid Rebind message from a client the server
can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field.
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
SHOULD return an empty IA with status set to NoBinding. SHOULD return an IA containing no addresses with status set to
NoBinding.
If the server finds that the addresses in the IA for the client do If the server finds that the addresses in the IA for the client
not match the clients binding the server should return an empty IA do not match the client binding the server should return an IA
with status set to RenwNoMatch. containing no addresses with status set to RebdNoMatch.
If the server cannot Renew addresses for the client it SHOULD If the server cannot Rebind addresses for the client it SHOULD send
send back an empty IA to the client with the status field set to back an IA containing no addresses to the client with the status
AddrUnavail. field set to AddrUnavail.
If the server finds the addresses in the IA for the client then the If the server finds the addresses in the IA for the client then the
server SHOULD send back the IA to the client with new lease times server SHOULD send back the IA to the client with new lifetimes and
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.
16.2.4. Receipt of Rebind messages
Upon the receipt of a valid Rebind message from a client the server
can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field.
The server then 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 Confirm message. transaction-ID The transaction-ID from the Rebind 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.
When the server receives a Rebind and IA option from a client it
SHOULD locate the clients binding and verify the information in the
IA from the client matches the information stored for that client.
If the server cannot find a client entry for this IA the server
SHOULD return an empty IA with status set to NoBinding.
If the server finds that the addresses in the IA for the client do
not match the clients binding the server should return an empty IA
with status set to RebdNoMatch.
If the server cannot Rebind addresses for the client it SHOULD
send back an empty IA to the client with the status field set to
AddrUnavail.
If the server finds the addresses in the IA for the client then the
server SHOULD send back the IA to the client with new lease times
and T1/T2 times if the default is not being used, and set status to
Success.
There is a significant difference between Renew and Rebind messages: There is a significant difference between Renew and Rebind messages:
Because the Renew message is processed by a single server, the Because the Renew message is processed by a single server, the
responding server can actually change the addresses in the IA. responding server can actually change the addresses in the IA.
However, because multiple servers may respond to a Rebind, all they However, because multiple servers may respond to a Rebind, all they
can safely do is update T1, T2 (for the IA) and lifetimes (for can safely do is update T1, T2 (for the IA) and lifetimes (for
individual addresses). individual addresses).
16.2.5. Receipt of Release messages 16.2.5. Receipt of Inform messages
When the server receives an Inform message, the client is requesting
configuration information that does not include the assignment of any
addresses. The server SHOULD determine all configuration parameters
appropriate to the client, based on the server configuration policies
known to the server.
Upon the receipt of a valid Inform message from a client the server
can respond to, (implementation-specific administrative policy
satisfied) the server scans the options field. The server then
constructs a Reply message and sends it to the client.
The server SHOULD process each option for the client in an
implementation-specific manner. The server MUST construct a Reply
message containing the following values:
msg-type REPLY
transaction-ID The transaction-ID from the Inforrm message.
server address One of the IP addresses assigned to the interface
through which the server received the message
from the client.
The server adds options to the Reply message for all of the
configuration parameters to be returned to the client.
16.2.6. 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 then generates a Reply message. If all of the IAs were If all of the IAs were valid and the addresses successfully released,
valid and the addresses successfully released, the server includes the server generates a Reply message and includes a Status Code
a Status Code option with value Success. If any of the IAs were option with value Success. The server MUST NOT include any other
invalid or if any of the addresses were not successfully released, options in the Reply message.
the server leaves all of the IAs in the message unchanged (the server
releases none of the addresses in any of the IAs in the message) and
includes a Status Code option with value NoBinding. The server MUST
NOT include any other options in the Reply message.
A client can send an option containing an IA with no listed addresses
to release implicitly all of the addresses in the IA.
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.
16.2.6. Receipt of Decline messages 16.2.7. 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 then generates a Reply message. If all of the IAs were If all of the IAs were valid and the addresses successfully declined,
valid and the addresses successfully declined,, the server includes the server generates a Reply message and includes a Status Code
a Status Code option with value Success. If any of the IAs were option with value Success. The server MUST NOT include any other
invalid or if any of the addresses were not successfully declined, options in the Reply message.
the server leaves all of the IAs in the message unchanged (the server
releases none of the addresses in any of the IAs in the message) and
includes a Status Code option with value NoBinding. The server MUST
NOT include any other options in the Reply message.
A client can send an option containing an IA with no listed addresses 16.2.8. Receipt of Decline messages
to decline implicitly all of the addresses in the IA.
16.2.7. Sending of Reply messages Upon the receipt of a valid Inform message, the server determines the
appropriate configuration parameters and returns those parameters to
the client in a Reply message. The server MUST NOT include any IA
options in the Reply message.
If the Request, Confirm, Renew, Rebind, Release or Decline message 16.2.9. Sending of Reply messages
from the client was originally received in a Relay-forward message
from a relay, the server places the Reply message in the options If the Request, Confirm, Renew, Rebind, Release, Decline or Inform
field of a Relay-response message and copies the link-prefix and message from the client was originally received in a Relay-forward
client-return-address fields from the Relay-forward message into the message from a relay, the server places the Reply message in the
Relay-response message. options field of a Relay-response message and copies the link-address
and client-return-address fields from the Relay-forward message into
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 17. 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 17.1. Server Behavior
A server sends a Reconfigure-init message to cause a client to A server sends a Reconfigure-init message to cause a client to
initiate immediately a Request/Reply message exchange with the initiate immediately a Rebind/Reply message exchange with the server.
server.
17.1.1. Creation and transmission of Reconfigure-init messages 17.1.1. Creation and transmission of Reconfigure-init messages
The server sets the "msg-type" field to RECONFIG-INIT. The server The server sets the "msg-type" field to RECONFIG-INIT. 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.
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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 send
a Reconfigure-init message to additional clients while previous a Reconfigure-init 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-init message causes the client to initiate a
Request/Reply message exchange with the server. The server Rebind/Reply message exchange with the server. The server interprets
interprets the receipt of a Request message from the client as the receipt of a Rebind message from the client as satisfying the
satisfying the Reconfigure-init message request. Reconfigure-init message request.
17.1.2. Time out and retransmission of Reconfigure-init messages 17.1.2. Time out and retransmission of Reconfigure-init messages
If the server does not receive a Request message from the client If the server does not receive a Rebind message from the client
in RECREP_MSG_TIMEOUT milliseconds, the server retransmits in RECREP_MSG_TIMEOUT milliseconds, the server retransmits
the Reconfigure-init message, doubles the RECREP_MSG_TIMEOUT the Reconfigure-init 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 Request messages 17.1.3. Receipt of Rebind 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 16.2.7, including in the "options" field new described in section 16.2.9, including in the "options" field new
values for configuration parameters. values for configuration parameters.
It is possible that the client may send a Request message after the It is possible that the client may send a Rebind message after the
server has sent a Reconfigure-init but before the Reconfigure-init server has sent a Reconfigure-init but before the Reconfigure-init is
is received by the client. In this case, the Request message from received by the client. In this case, the Rebind message from the
the client may not include all of the IAs and requests for parameters client may not include all of the IAs and requests for parameters to
to be reconfigured by the server. To accommodate this scenario, the be reconfigured by the server. To accommodate this scenario, the
server MAY choose to send a Reply with the IAs and other parameters 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 to be reconfigured, even if those IAs and parameters were not in the
Request message from the client. Rebind message from the client.
17.2. Client Behavior 17.2. Client Behavior
A client MUST always monitor UDP port 546 for Reconfigure-init A client MUST always monitor UDP port 546 for Reconfigure-init
messages on interfaces upon which it has acquired DHCP parameters. messages on interfaces upon which it has acquired DHCP parameters.
Since the results of a reconfiguration event may affect application Since the results of a reconfiguration event may affect application
layer programs, the client SHOULD log these events, and MAY notify layer programs, the client SHOULD log these events, and MAY notify
these programs of the change through an implementation-specific these programs of the change through an implementation-specific
interface. interface.
17.2.1. Receipt of Reconfigure-init messages 17.2.1. Receipt of Reconfigure-init messages
Upon receipt of a valid Reconfigure-init message, the client Upon receipt of a valid Reconfigure-init message, the client
initiates a Request/Reply transaction with the server. While initiates a Rebind/Reply transaction with the server. While the
the Request/Reply transaction is in progress, the client silently Rebind/Reply transaction is in progress, the client silently discards
discards any Reconfigure-init messages it receives. any Reconfigure-init messages it receives.
DISCUSSION: DISCUSSION:
The Reconfigure-init message acts as a trigger that signals The Reconfigure-init message acts as a trigger that signals
the client to complete a successful Request/Reply message the client to complete a successful Rebind/Reply message
exchange. Once the client has received a Reconfigure-init, exchange. Once the client has received a Reconfigure-init,
the client proceeds with the Request/Reply message the client proceeds with the Rebind/Reply message
exchange (retransmitting the Request if necessary); the exchange (retransmitting the Rebind if necessary); the
client ignores any additional Reconfigure-init messages client ignores any additional Reconfigure-init messages
(regardless of the transaction ID in the Reconfigure-init (regardless of the transaction ID in the Reconfigure-init
message) until the Request/Reply exchange is complete. message) until the Rebind/Reply exchange is complete.
Subsequent Reconfigure-init messages (again independent Subsequent Reconfigure-init messages (again independent
of the transaction ID) cause the client to initiate a new of the transaction ID) cause the client to initiate a new
Request/Reply 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 retransmitted Reconfigure-init messages? Duplicate or retransmitted Reconfigure-init messages? Duplicate
messages will be ignored because the client will begin messages will be ignored because the client will begin
the Request/Reply exchange after the receipt of the the Rebind/Reply exchange after the receipt of the
first Reconfigure-init. Retransmitted messages will first Reconfigure-init. Retransmitted messages will
either trigger the Request/Reply exchange (if the first either trigger the Rebind/Reply exchange (if the first
Reconfigure-init was not received by the client) or will Reconfigure-init was not received by the client) or will
be ignored. The server can discontinue retransmission of be ignored. The server can discontinue retransmission of
Reconfigure-init messages to the client once the server Reconfigure-init messages to the client once the server
receives the Request 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 Reconfigure-init to be sufficiently delayed (and delivered
delivered out of order) to arrive at the client after out of order) to arrive at the client after the Rebind/Reply
the Request/Reply exchange (initiated by the original exchange (initiated by the original Reconfigure-init) has
Reconfigure-init) has been completed. In this case, the been completed. In this case, the client would initiate a
client would initiate a redundant Request/Reply exchange. redundant Rebind/Reply exchange. The likelihood of delayed
The 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.
17.2.2. Creation and sending of Request messages The consequence of the redundant exchange is inefficiency
rather than incorrect operation.
17.2.2. Creation and sending of Rebind messages
When responding to a Reconfigure-init, the client creates and When responding to a Reconfigure-init, the client creates and
sends the Request message in exactly the same manner as outlined in sends the Rebind message in exactly the same manner as outlined in
section 16.1.1 with the following difference: section 16.1.1 with the following difference:
IAs The client includes IA options containing the addresses the IAs The client includes IA options containing the addresses the
client currently has assigned to those IAs for the interface client currently has assigned to those IAs for the interface
through which the Reconfigure-init message was received. through which the Reconfigure-init message was received.
17.2.3. Time out and retransmission of Request messages 17.2.3. Time out and retransmission of Rebind messages
The client uses the same variables and retransmission algorithm as it The client uses the same variables and retransmission algorithm as
does with Request messages generated as part of a client-initiated it does with Rebind messages generated as part of a client-initiated
configuration exchange. See section 16.1.1 for details. configuration exchange. See section 16.1.1 for details.
17.2.4. Receipt of Reply messages 17.2.4. 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 As discussed in section 17.1.3, the Reply from the server may include
IAs and parameters that were not included in the Request message from 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 the client. The client MUST configure itself with all of the IAs and
parameters in the Reply from the server. parameters in the Reply from the server.
18. Relay Behavior 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 18.1. 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-prefix 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-prefix 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 20.15)in the Relay-forward message. The server will include section 20.16)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 20.7 that contains The relay constructs a "client-message" option 20.8 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 then sends 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.
18.2. Relaying of server messages 18.2. 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-prefix option. 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 19. 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
skipping to change at page 54, line 18 skipping to change at page 55, line 24
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 IA | option-len | | OPTION IA | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) | | IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 | | T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 | | T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IA status | num-addrs |T| addr status | prefix length | | IA Status | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+ |
| | . Options .
| IPv6 address | . .
| (16 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T| addr status | prefix length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| IPv6 address |
| (16 octets) |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | preferred lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pref. lifetime (cont.) | valid lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid lifetime (cont.) |T| addr status | prefix length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 address |
| (16 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_IA (TBD) option-code OPTION_IA (TBD)
option-len Variable; equal to 24 + num-addrs*26 option-len Variable; equal to 13 + number of bytes
required for ``options''
IA ID The unique identifier for this IA; chosen by IA ID The unique identifier for this IA; chosen by
the client 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.
T When set to 1, indicates that this address is
a "temporary address" [15]; when set to 0,
the address is not a temporary address.
IA status Status of the IA in this option. IA status Status of the IA in this option.
num-addrs An unsigned integer giving the number of options Options associated with this IA
addresses carried in this IA option (MAY be The Options field carries those options that are specific to this
zero). IA. This includes all of the Address Options to carry the addresses
associated with this IA.
addr status Status of the addresses in this IA. 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
expired, the IA can be considered as having expired. T1 and T2
are included to give servers explicit control over when a client
recontacts the server about a specific IA.
20.4. IA Address option
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_IAADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T| addr status | prefix length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| IPv6 address |
| (16 octets) |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | preferred lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pref. lifetime (cont.) | valid lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid lifetime (cont.) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. Options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_IADDR (TBD)
option-len The number of bytes in the data area of this option
T When set to 1, indicates that this address is a
"temporary address" [15]; when set to 0, the 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.
prefix length Prefix length for this address. prefix length Prefix length for this address.
IPv6 address An IPv6 address assigned to this IA. IPv6 address An IPv6 address
preferred lifetime The preferred lifetime for the associated preferred lifetime The preferred lifetime for the IPv6 address in
IPv6 address. the option.
valid lifetime The valid lifetime for the associated IPv6 valid lifetime The valid lifetime for the IPv6 address in the
address. option
The "IPv6 address", "preferred lifetime" and "valid lifetime" fields options Options associated with this address
are repeated for each address in the IA option (as determined by the
"num-addrs" field).
Note that an IA has no explicit "lifetime" or "lease length" of The IA Address option is used to specify IPv6 addresses associated
its own. When the lifetimes of all of the addresses in an IA have with an IA. It may only appear in an IA option.
expired, the IA can be considered as having expired. T1 and T2
are included to give servers explicit control over when a client
recontacts the server about a specific IA.
The 'T' bit identifies the associated address as a temporary address. The Options field carries those options that are specific to this
If the server is configured to assign temporary addresses to the address.
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.
20.4. Option request option 20.5. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 56, line 29 skipping to change at page 58, line 5
option-len Variable; equal to twice the number of option codes option-len Variable; equal to twice the number of option codes
carried in this option. carried in this option.
option-data A list of the option codes for the options requested option-data A list of the option codes for the options requested
in this option. in this option.
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.
20.5. Preference option 20.6. 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 MUST be 1
option-data The preference value for the server in this message. option-data 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 15.1.3
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.
20.6. Elapsed Time 20.7. 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)
skipping to change at page 57, line 28 skipping to change at page 58, line 49
option-data The amount of time since the client began its option-data 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 MAY use the data value in this option as input to policy
controlling how a server responds to a client message. controlling how a server responds to a client message.
20.7. 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 Variable; equal to the length of the forwarded DHCP
client message. client message.
option-data The message received from the client; forwarded option-data The message received from the client; forwarded
verbatim to the server. verbatim to the server.
20.8. Server message option 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.
20.9. 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 Variable; equal to the length of the forwarded DHCP
server message. server message.
option-data The message received from the server; forwarded option-data The message received from the server; forwarded
verbatim to the client. verbatim to the client.
20.9. DSTM Global IPv4 Address Option 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
message.
20.10. 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) following this option will
contain an IPv4-Mapped IPv6 Address [9] in the case of a Client contain an IPv4-Mapped IPv6 Address [9] in the case of a Client
receiving the option, or is a Request for an IPv4-Mapped IPv6 Address receiving the option, or is a Request for an IPv4-Mapped IPv6 Address
from a client in the case of a DHCPv6 Server receiving the option. 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 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. Tunnel Endpoint (TEP) to encapsulate an IPv6 packet within IPv6.
This option can be used with the Request, Reply, and Reconfigure-Init This option can be used with the Request, Reply, and Reconfigure-Init
skipping to change at page 59, line 4 skipping to change at page 60, line 27
| Tunnel End Point (TEP) | | Tunnel End Point (TEP) |
| (If Present) | | (If Present) |
| (16 octets) | | (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option code OPTION_DSTM (TBD) option code OPTION_DSTM (TBD)
option length Variable: 0 or multiple of 16 option length Variable: 0 or multiple of 16
tunnel end point IPv6 Address or addresses if Present tunnel end point IPv6 Address or addresses if Present
A DSTM IPv4 Global Address Option MUST only apply to the IA following A DSTM IPv4 Global Address Option MUST only apply to the IA following
this option. this option.
20.10. Authentication option 20.11. 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 19.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 60, line 5 skipping to change at page 61, line 25
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
20.11. Server unicast option 20.12. Server unicast option
This option is used by a server to send to a client to inform This option is used by a server to send to a client to inform
the client it MAY send a Request, Renew, Release, and Decline by the client it MAY send a Request, Renew, Release, and Decline by
unicasting directly to the server instead of the All_DHCPv6_Agents unicasting directly to the server instead of the All_DHCPv6_Agents
Multicast address as an optimization, when the client as an address Multicast address as an optimization, when the client as an address
of sufficient scope to reach the server. of sufficient scope to reach the server.
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-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_UNICAST (TBD) option-code OPTION_UNICAST (TBD)
option-length 0 option-length 0
This option only applies to the server address that sends this to the This option only applies to the server address that sends this to the
client. client.
20.12. Domain Search Option 20.13. 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-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Search List | | Domain Search List |
skipping to change at page 60, line 49 skipping to change at page 62, line 23
option-code OPTION_DOMAIN_SEARCH_LIST (TBD) option-code OPTION_DOMAIN_SEARCH_LIST (TBD)
option-length variable option-length variable
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, So that the search list may be encoded compactly and uniformly,
search strings in the search list are concatenated and encoded using search strings in the search list are concatenated and encoded using
the technique described in section 4.1 of [13]. the technique described in section 3.1 of [13].
For use in this specification, the compression pointer (see section For use in this specification, the compression pointer (see section
4.1.4 of [13]) refers to the offset within the SearchString portion 4.1.4 of [13]) refers to the offset within the SearchString portion
of the option. of the option.
20.13. Domain Name Server Option 20.14. Domain Name Server Option
This option provides a list of Domain Name System [13] that a client This option provides a list of Domain Name System [13] that a client
name resolver can use to access DNS services. There must be at least name resolver can use to access DNS services. There must be at least
1 server listed in this option. 1 server listed in this 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_DNS_SERVERS | option_length | | OPTION_DNS_SERVERS | option_length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| DNS server (IP address) | | DNS server (IP address) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_DNS_SERVERS (11) option-code OPTION_DNS_SERVERS (11)
option-length variable option-length variable
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 DNS servers are listed in
the order of preference for use by the client the order of preference for use by the client
resolver. resolver.
20.14. Status Code Option 20.15. Status Code Option
This option returns indications of status not related to a specific This option returns indications of status not related to a specific
option. 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_STATUS_CODE | option-length | | OPTION_STATUS_CODE | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| status-code | status-message | | status-code | status-message |
skipping to change at page 62, line 4 skipping to change at page 63, line 26
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-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| status-code | status-message | | status-code | status-message |
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_STATUS_CODE (TBD) option-code OPTION_STATUS_CODE (TBD)
option-length variable 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.
20.15. Circuit-ID Option 20.16. Circuit-ID Option
This option provides a mechanism through which a relay agent can This option provides a mechanism through which a relay agent can
identify the network attachment point through which a message was identify the network attachment point through which a message was
received from a DHCP client. 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_length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CIRCUIT_ID | option_length | | OPTION_CIRCUIT_ID | option_length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Circuit-ID | | Circuit-ID |
. . . .
. . . .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CIRCUIT_ID (TBD) option-code OPTION_CIRCUIT_ID (TBD)
option-length variable option-length variable
Circuit-ID An opaque value of arbitrary length; this Circuit-ID An opaque value of arbitrary length; this
value must uniquely identify one of the value must uniquely identify one of the
network attachments used by the relay agent network attachments used by the relay agent
20.16. User Class Option 20.17. 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. Based on this class, a DHCP server
selects the appropriate address pool to assign an address to the selects the appropriate address pool to assign an address to the
client and the appropriate configuration parameters. 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 63, line 49 skipping to change at page 65, line 9
the opaque user class data in network byte order. the opaque user class data in network byte order.
Servers may interpret the meanings of multiple class specifications Servers may 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).
20.17. Vendor Class Option 20.18. Vendor Class Option
This option is used by clients and servers to exchange vendor- This option is used by clients and servers to exchange vendor-
specific information. The definition of this information is vendor specific information. The definition of this information is vendor
specific. The vendor is indicated in the vendor class identifier specific. The vendor is indicated in the vendor class identifier
option. Servers not equipped to interpret the vendor-specific option. Servers not equipped to interpret the vendor-specific
information sent by a client MUST ignore it (although it may be information sent by a client MUST ignore it (although it may be
reported). Clients which do not receive desired vendor-specific reported). Clients which do not receive desired vendor-specific
information SHOULD make an attempt to operate without it, although information SHOULD make an attempt to operate without it, although
they may do so(and announce they are doing so) in a degraded mode. they may do so(and announce they are doing so) in a degraded mode.
skipping to change at page 66, line 20 skipping to change at page 67, line 26
23.5. Status codes 23.5. 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 23.6. Authentication option
Section 19 defines three new name spaces associated with the Section 19 defines three new name spaces associated with the
Authentication Option (section 20.10), which are to be created and Authentication Option (section 20.11), 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 19.5) and 1 (for the delayed
authentication Protocol in section 19.6). Additional protocols may authentication Protocol in section 19.6). 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
skipping to change at page 67, line 12 skipping to change at page 68, line 19
Ted Lemon, Jack McCann, Yakov Rekhter, Matt Thomas, Sue Thomson, Ted Lemon, Jack McCann, Yakov Rekhter, Matt Thomas, Sue Thomson,
Bernie Volz and Phil Wells. 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 19.
The Domain Search option described in section 20.12 is based on the The Domain Search option described in section 20.13 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.
A. Comparison between DHCPv4 and DHCPv6 A. Full Copyright Statement
This appendix is provided for readers who will find it useful to see
a model and architecture comparison between DHCPv4 [7, 2] and DHCPv6.
There are three key reasons for the differences:
o IPv6 inherently supports a new model and architecture for
communications and autoconfiguration of addresses.
o DHCPv6 benefits from the new IPv6 features.
o New features were added to support the expected evolution and
the existence of more complicated Internet network service
requirements.
IPv6 Architecture/Model Changes:
o The link-local address permits a node to have an address
immediately when the node boots, which means all clients have a
source IP address at all times to locate an on-link server or
relay.
o The need for BOOTP compatibility and the broadcast flag have been
removed.
o Multicast and address scoping in IPv6 permit the design of
discovery packets that would inherently define their range by the
multicast address for the function required.
o Stateful autoconfiguration has to coexist and integrate with
stateless address autoconfiguration supporting duplicate address
detection [20] and the two IPv6 address lifetimes, to facilitate
the dynamic renumbering of addresses and the management of those
addresses.
o Multiple addresses per interface are inherently supported in
IPv6.
o Some DHCPv4 options are unnecessary now because the configuration
parameters are either obtained through IPv6 Neighbor Discovery or
the Service Location protocol [21].
DHCPv6 Architecture/Model Changes:
o The message type is the first octet in the packet.
o IPv6 Address allocations are now handled in a message option as
opposed to the message header.
o Client/Server bindings are now mandatory and take advantage
of the link-local address of the client to always permit
communications either directly from an on-link server, or from a
off-link server through an on-link relay.
o Servers are discovered by a client Solicit, followed by a server
Advertise message
o The client will know if the server is on-link or off-link.
o The on-link relay may locate off-link server addresses from
system configuration or by the use of a site-wide multicast
packet.
o ACKs and NAKs are not used.
o The server assumes the client receives its responses unless it
receives a retransmission of the same client request. This
permits recovery in the case where the network has faulted.
o Clients can issue multiple, unrelated Request messages to the
same or different servers.
o The function of DHCPINFORM is inherent in the new packet design;
a client can request configuration parameters other than IPv6
addresses in the optional option headers.
o Clients MUST listen to their UDP port for the new
Reconfigure-init message from servers.
o New options have been defined.
With the changes just enumerated, we can support new user features,
including
o Configuration of Dynamic Updates to DNS
o Address deprecation, for dynamic renumbering.
o Relays can be preconfigured with server addresses, or use of
multicast.
o Authentication
o Clients can ask for multiple IP addresses.
o Addresses can be reclaimed using the Reconfigure-init message.
o Integration between stateless and stateful address
autoconfiguration.
o Enabling relays to locate off-link servers.
B. 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,
this document itself may not be modified in any way, such as by this document itself may not be modified in any way, such as by
skipping to change at page 70, line 51 skipping to change at page 70, line 11
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. [18] J. Postel. User Datagram Protocol, August 1980. RFC 768.
[19] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC [19] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC
1321. 1321.
[20] S. Thomson and T. Narten. IPv6 Stateless Address [20] S. Thomson and T. Narten. IPv6 Stateless Address
Autoconfiguration, December 1998. RFC 2462. Autoconfiguration, December 1998. RFC 2462.
[21] J. Veizades, E. Guttman, C. Perkins, and S. Kaplan. Service [21] P. Vixie, Ed., S. Thomson, Y. Rekhter, and J. Bound. Dynamic
Location Protocol, June 1997. RFC 2165.
[22] 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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