draft-ietf-dhc-dhcpv6-27.txt   draft-ietf-dhc-dhcpv6-28.txt 
Internet Engineering Task Force R. Droms (ed.), Cisco Internet Engineering Task Force R. Droms (ed.), Cisco
INTERNET DRAFT J. Bound, Hewlett Packard INTERNET DRAFT J. Bound, Hewlett Packard
DHC Working Group Bernie Volz, Ericsson DHC Working Group Bernie Volz, Ericsson
Obsoletes: draft-ietf-dhc-dhcpv6-26.txt Ted Lemon, Nominum Obsoletes: draft-ietf-dhc-dhcpv6-27.txt Ted Lemon, Nominum
C. Perkins, Nokia Research Center C. Perkins, Nokia Research Center
M. Carney, Sun Microsystems M. Carney, Sun Microsystems
22 Oct 2003 2 Nov 2002
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
draft-ietf-dhc-dhcpv6-27.txt draft-ietf-dhc-dhcpv6-28.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 150 skipping to change at page 1, line 150
18.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 39 18.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 39
18.2.1. Receipt of Request Messages . . . . . . . . . . . 40 18.2.1. Receipt of Request Messages . . . . . . . . . . . 40
18.2.2. Receipt of Confirm Messages . . . . . . . . . . . 41 18.2.2. Receipt of Confirm Messages . . . . . . . . . . . 41
18.2.3. Receipt of Renew Messages . . . . . . . . . . . . 41 18.2.3. Receipt of Renew Messages . . . . . . . . . . . . 41
18.2.4. Receipt of Rebind Messages . . . . . . . . . . . 42 18.2.4. Receipt of Rebind Messages . . . . . . . . . . . 42
18.2.5. Receipt of Information-request Messages . . . . . 42 18.2.5. Receipt of Information-request Messages . . . . . 42
18.2.6. Receipt of Release Messages . . . . . . . . . . . 43 18.2.6. Receipt of Release Messages . . . . . . . . . . . 43
18.2.7. Receipt of Decline Messages . . . . . . . . . . . 44 18.2.7. Receipt of Decline Messages . . . . . . . . . . . 44
18.2.8. Transmission of Reply Messages . . . . . . . . . 44 18.2.8. Transmission of Reply Messages . . . . . . . . . 44
19. DHCP Server-Initiated Configuration Exchange 44 19. DHCP Server-Initiated Configuration Exchange 45
19.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 45 19.1. Server Behavior . . . . . . . . . . . . . . . . . . . . . 45
19.1.1. Creation and Transmission of Reconfigure Messages 45 19.1.1. Creation and Transmission of Reconfigure Messages 45
19.1.2. Time Out and Retransmission of Reconfigure 19.1.2. Time Out and Retransmission of Reconfigure
Messages . . . . . . . . . . . . . . . . . 46 Messages . . . . . . . . . . . . . . . . . 46
19.2. Receipt of Renew Messages . . . . . . . . . . . . . . . . 46 19.2. Receipt of Renew Messages . . . . . . . . . . . . . . . . 46
19.3. Receipt of Information-request Messages . . . . . . . . . 46 19.3. Receipt of Information-request Messages . . . . . . . . . 46
19.4. Client Behavior . . . . . . . . . . . . . . . . . . . . . 47 19.4. Client Behavior . . . . . . . . . . . . . . . . . . . . . 47
19.4.1. Receipt of Reconfigure Messages . . . . . . . . . 47 19.4.1. Receipt of Reconfigure Messages . . . . . . . . . 47
19.4.2. Creation and Transmission of Renew Messages . . . 48 19.4.2. Creation and Transmission of Renew Messages . . . 48
19.4.3. Creation and Transmission of Information-request 19.4.3. Creation and Transmission of Information-request
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20. Relay Agent Behavior 48 20. Relay Agent Behavior 48
20.1. Relaying a Client Message or a Relay-forward Message . . 49 20.1. Relaying a Client Message or a Relay-forward Message . . 49
20.1.1. Relaying a Message from a Client . . . . . . . . 49 20.1.1. Relaying a Message from a Client . . . . . . . . 49
20.1.2. Relaying a Message from a Relay Agent . . . . . . 49 20.1.2. Relaying a Message from a Relay Agent . . . . . . 49
20.2. Relaying a Relay-reply Message . . . . . . . . . . . . . 50 20.2. Relaying a Relay-reply Message . . . . . . . . . . . . . 50
20.3. Construction of Relay-reply Messages . . . . . . . . . . 50 20.3. Construction of Relay-reply Messages . . . . . . . . . . 50
21. Authentication of DHCP Messages 51 21. Authentication of DHCP Messages 51
21.1. Security of Messages Sent Between Servers and Relay Agents 51 21.1. Security of Messages Sent Between Servers and Relay Agents 51
21.2. Summary of DHCP Authentication . . . . . . . . . . . . . 52 21.2. Summary of DHCP Authentication . . . . . . . . . . . . . 52
21.3. Replay Detection . . . . . . . . . . . . . . . . . . . . 52 21.3. Replay Detection . . . . . . . . . . . . . . . . . . . . 53
21.4. Delayed Authentication Protocol . . . . . . . . . . . . . 52 21.4. Delayed Authentication Protocol . . . . . . . . . . . . . 53
21.4.1. Use of the Authentication Option in the Delayed 21.4.1. Use of the Authentication Option in the Delayed
Authentication Protocol . . . . . . . . . 53 Authentication Protocol . . . . . . . . . 53
21.4.2. Message Validation . . . . . . . . . . . . . . . 54 21.4.2. Message Validation . . . . . . . . . . . . . . . 54
21.4.3. Key Utilization . . . . . . . . . . . . . . . . . 54 21.4.3. Key Utilization . . . . . . . . . . . . . . . . . 55
21.4.4. Client Considerations for Delayed Authentication 21.4.4. Client Considerations for Delayed Authentication
Protocol . . . . . . . . . . . . . . . . . 54 Protocol . . . . . . . . . . . . . . . . . 55
21.4.5. Server Considerations for Delayed Authentication 21.4.5. Server Considerations for Delayed Authentication
Protocol . . . . . . . . . . . . . . . . . 56 Protocol . . . . . . . . . . . . . . . . . 57
21.5. Reconfigure Key Authentication Protocol . . . . . . . . . 57 21.5. Reconfigure Key Authentication Protocol . . . . . . . . . 57
21.5.1. Use of the Authentication Option in the Reconfigure 21.5.1. Use of the Authentication Option in the Reconfigure
Key Authentication Protocol . . . . . . . 57 Key Authentication Protocol . . . . . . . 58
21.5.2. Server considerations for Reconfigure Key protocol 58 21.5.2. Server considerations for Reconfigure Key protocol 58
21.5.3. Client considerations for Reconfigure Key protocol 58 21.5.3. Client considerations for Reconfigure Key protocol 59
22. DHCP Options 58 22. DHCP Options 59
22.1. Format of DHCP Options . . . . . . . . . . . . . . . . . 59 22.1. Format of DHCP Options . . . . . . . . . . . . . . . . . 60
22.2. Client Identifier Option . . . . . . . . . . . . . . . . 59 22.2. Client Identifier Option . . . . . . . . . . . . . . . . 60
22.3. Server Identifier Option . . . . . . . . . . . . . . . . 60 22.3. Server Identifier Option . . . . . . . . . . . . . . . . 61
22.4. Identity Association for Non-temporary Addresses Option . 60 22.4. Identity Association for Non-temporary Addresses Option . 61
22.5. Identity Association for Temporary Addresses Option . . . 62 22.5. Identity Association for Temporary Addresses Option . . . 63
22.6. IA Address Option . . . . . . . . . . . . . . . . . . . . 64 22.6. IA Address Option . . . . . . . . . . . . . . . . . . . . 65
22.7. Option Request Option . . . . . . . . . . . . . . . . . . 65 22.7. Option Request Option . . . . . . . . . . . . . . . . . . 66
22.8. Preference Option . . . . . . . . . . . . . . . . . . . . 65 22.8. Preference Option . . . . . . . . . . . . . . . . . . . . 66
22.9. Elapsed Time Option . . . . . . . . . . . . . . . . . . . 66 22.9. Elapsed Time Option . . . . . . . . . . . . . . . . . . . 67
22.10. Relay Message Option . . . . . . . . . . . . . . . . . . 67 22.10. Relay Message Option . . . . . . . . . . . . . . . . . . 68
22.11. Authentication Option . . . . . . . . . . . . . . . . . . 67 22.11. Authentication Option . . . . . . . . . . . . . . . . . . 68
22.12. Server Unicast Option . . . . . . . . . . . . . . . . . . 68 22.12. Server Unicast Option . . . . . . . . . . . . . . . . . . 69
22.13. Status Code Option . . . . . . . . . . . . . . . . . . . 69 22.13. Status Code Option . . . . . . . . . . . . . . . . . . . 70
22.14. Rapid Commit Option . . . . . . . . . . . . . . . . . . . 69 22.14. Rapid Commit Option . . . . . . . . . . . . . . . . . . . 71
22.15. User Class Option . . . . . . . . . . . . . . . . . . . . 70 22.15. User Class Option . . . . . . . . . . . . . . . . . . . . 71
22.16. Vendor Class Option . . . . . . . . . . . . . . . . . . . 71 22.16. Vendor Class Option . . . . . . . . . . . . . . . . . . . 73
22.17. Vendor-specific Information Option . . . . . . . . . . . 72 22.17. Vendor-specific Information Option . . . . . . . . . . . 73
22.18. Interface-Id Option . . . . . . . . . . . . . . . . . . . 74 22.18. Interface-Id Option . . . . . . . . . . . . . . . . . . . 75
22.19. Reconfigure Message Option . . . . . . . . . . . . . . . 75 22.19. Reconfigure Message Option . . . . . . . . . . . . . . . 76
22.20. Reconfigure Accept Option . . . . . . . . . . . . . . . . 75 22.20. Reconfigure Accept Option . . . . . . . . . . . . . . . . 76
23. Security Considerations 76 23. Security Considerations 77
24. IANA Considerations 77 24. IANA Considerations 78
24.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 78 24.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 79
24.2. DHCP Message Types . . . . . . . . . . . . . . . . . . . 78 24.2. DHCP Message Types . . . . . . . . . . . . . . . . . . . 79
24.3. DHCP Options . . . . . . . . . . . . . . . . . . . . . . 79 24.3. DHCP Options . . . . . . . . . . . . . . . . . . . . . . 80
24.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 80 24.4. Status Codes . . . . . . . . . . . . . . . . . . . . . . 81
24.5. DUID . . . . . . . . . . . . . . . . . . . . . . . . . . 80 24.5. DUID . . . . . . . . . . . . . . . . . . . . . . . . . . 81
25. Acknowledgments 80 25. Acknowledgments 82
26. Changes in draft-ietf-dhc-dhcpv6-27.txt 81 26. Changes in draft-ietf-dhc-dhcpv6-27.txt 82
References 82 27. Changes in draft-ietf-dhc-dhcpv6-28.txt 83
Chair's Address 83 References 84
Authors' Addresses 84 Chair's Address 85
A. Appearance of Options in Message Types 85 Authors' Addresses 86
B. Appearance of Options in the Options Field of DHCP Options 85 A. Appearance of Options in Message Types 87
C. Full Copyright Statement 86 B. Appearance of Options in the Options Field of DHCP Options 87
C. Full Copyright Statement 88
1. Introduction and Overview 1. Introduction and Overview
This document describes DHCP for IPv6 (DHCP), a client/server This document describes DHCP for IPv6 (DHCP), a client/server
protocol that provides managed configuration of devices. protocol that provides managed configuration of devices.
DHCP can provide a device with addresses assigned by a DHCP server DHCP can provide a device with addresses assigned by a DHCP server
and other configuration information, which are carried in options. and other configuration information, which are carried in options.
DHCP can be extended through the definition of new options to carry DHCP can be extended through the definition of new options to carry
configuration information not specified in this document. configuration information not specified in this document.
DHCP is the "stateful address autoconfiguration protocol" and the DHCP is the "stateful address autoconfiguration protocol" and the
"stateful autoconfiguration protocol" referred to in "IPv6 Stateless "stateful autoconfiguration protocol" referred to in "IPv6 Stateless
Address Autoconfiguration" [20]. Address Autoconfiguration" [21].
The operational models and relevant configuration information for The operational models and relevant configuration information for
DHCPv4 [1][5] and DHCPv6 are sufficiently different that integration DHCPv4 [1][6] and DHCPv6 are sufficiently different that integration
between the two services is not included in this document. If there between the two services is not included in this document. If there
is sufficient interest and demand, integration can be specified is sufficient interest and demand, integration can be specified
in a document that extends DHCPv6 to carry IPv4 addresses and in a document that extends DHCPv6 to carry IPv4 addresses and
configuration information. configuration information.
The remainder of this introduction summarizes DHCP, explaining The remainder of this introduction summarizes DHCP, explaining
the message exchange mechanisms and example message flows. The the message exchange mechanisms and example message flows. The
message flows in sections 1.2 and 1.3 are intended as illustrations message flows in sections 1.2 and 1.3 are intended as illustrations
of DHCP operation rather than an exhaustive list of all possible of DHCP operation rather than an exhaustive list of all possible
client-server interactions. Sections 17, 18 and 19 explain client client-server interactions. Sections 17, 18 and 19 explain client
and server operation in detail. and server operation in detail.
1.1. Protocols and Addressing 1.1. Protocols and Addressing
Clients and servers exchange DHCP messages using UDP [18]. The Clients and servers exchange DHCP messages using UDP [19]. The
client uses a link-local address or addresses determined through client uses a link-local address or addresses determined through
other mechanisms for transmitting and receiving DHCP messages. other mechanisms for transmitting and receiving DHCP messages.
DHCP servers receive messages from clients using a reserved, DHCP servers receive messages from clients using a reserved,
link-scoped multicast address. A DHCP client transmits most messages link-scoped multicast address. A DHCP client transmits most messages
to this reserved multicast address, so that the client need not be to this reserved multicast address, so that the client need not be
configured with the address or addresses of DHCP servers. configured with the address or addresses of DHCP servers.
To allow a DHCP client to send a message to a DHCP server that is not To allow a DHCP client to send a message to a DHCP server that is not
attached to the same link, a DHCP relay agent on the client's link attached to the same link, a DHCP relay agent on the client's link
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description of message relaying by relay agents. description of message relaying by relay agents.
Once the client has determined the address of a server, it may Once the client has determined the address of a server, it may
under some circumstances send messages directly to the server using under some circumstances send messages directly to the server using
unicast. unicast.
1.2. Client-server Exchanges Involving Two Messages 1.2. Client-server Exchanges Involving Two Messages
When a DHCP client does not need to have a DHCP server assign When a DHCP client does not need to have a DHCP server assign
it IP addresses, the client can obtain configuration information it IP addresses, the client can obtain configuration information
such as a list of available DNS servers [7] or NTP servers [21] such as a list of available DNS servers [8] or NTP servers [22]
through a single message and reply exchanged with a DHCP server. through a single message and reply exchanged with a DHCP server.
To obtain configuration information the client first sends an To obtain configuration information the client first sends an
Information-Request message to the All_DHCP_Relay_Agents_and_Servers Information-Request message to the All_DHCP_Relay_Agents_and_Servers
multicast address. Servers respond with a Reply message containing multicast address. Servers respond with a Reply message containing
the configuration information for the client. the configuration information for the client.
This message exchange assumes that the client requires only This message exchange assumes that the client requires only
configuration information and does not require the assignment of any configuration information and does not require the assignment of any
IPv6 addresses. IPv6 addresses.
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from the server. The client sends a Solicit message to the from the server. The client sends a Solicit message to the
All_DHCP_Relay_Agents_and_Servers address to find available DHCP All_DHCP_Relay_Agents_and_Servers address to find available DHCP
servers. Any server that can meet the client's requirements servers. Any server that can meet the client's requirements
responds with an Advertise message. The client then chooses one responds with an Advertise message. The client then chooses one
of the servers and sends a Request message to the server asking of the servers and sends a Request message to the server asking
for confirmed assignment of addresses and other configuration for confirmed assignment of addresses and other configuration
information. The server responds with a Reply message that contains information. The server responds with a Reply message that contains
the confirmed addresses and configuration. the confirmed addresses and configuration.
As described in the previous section, the client sends a Renew As described in the previous section, the client sends a Renew
messages to the server to extend the lifetimes associated with its message to the server to extend the lifetimes associated with its
addresses, allowing the client to continue to use those addresses addresses, allowing the client to continue to use those addresses
without interruption. without interruption.
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 [2]. 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
specific variable names, how their values change, and how their specific variable names, how their values change, and how their
settings influence protocol behavior are provided to demonstrate settings influence protocol behavior are provided to demonstrate
protocol behavior. An implementation is not required to have them in protocol behavior. An implementation is not required to have them in
the exact form described here, so long as its external behavior is the exact form described here, so long as its external behavior is
consistent with that described in this document. consistent with that described in this document.
3. Background 3. Background
The IPv6 Specification provides the base architecture and design of The IPv6 Specification provides the base architecture and design of
IPv6. Related work in IPv6 that would best serve an implementor IPv6. Related work in IPv6 that would best serve an implementor
to study includes the IPv6 Specification [4], the IPv6 Addressing to study includes the IPv6 Specification [5], the IPv6 Addressing
Architecture [8], IPv6 Stateless Address Autoconfiguration [20], IPv6 Architecture [9], IPv6 Stateless Address Autoconfiguration [21], IPv6
Neighbor Discovery Processing [16], and Dynamic Updates to DNS [22]. Neighbor Discovery Processing [17], and Dynamic Updates to DNS [23].
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 [8] 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. The availability of these features means that during initialization. The availability of these features means that
a client can use its link-local address and a well-known multicast a client can use its link-local address and a well-known multicast
address to discover and communicate with DHCP servers or relay agents address to discover and communicate with DHCP servers or relay agents
on its link. on its link.
IPv6 Stateless Address Autoconfiguration [20] specifies procedures IPv6 Stateless Address Autoconfiguration [21] specifies procedures
by which a node may autoconfigure addresses based on router by which a node may autoconfigure addresses based on router
advertisements [16], and the use of a valid lifetime to support advertisements [17], and the use of a valid lifetime to support
renumbering of addresses on the Internet. In addition the renumbering of addresses on the Internet. In addition the
protocol interaction by which a node begins stateless or stateful protocol interaction by which a node begins stateless or stateful
autoconfiguration is specified. DHCP is one vehicle to perform autoconfiguration is specified. DHCP is one vehicle to perform
stateful autoconfiguration. Compatibility with stateless address stateful autoconfiguration. Compatibility with stateless address
autoconfiguration is a design requirement of DHCP. autoconfiguration is a design requirement of DHCP.
IPv6 Neighbor Discovery [16] is the node discovery protocol in IPv6 IPv6 Neighbor Discovery [17] is the node discovery protocol in IPv6
which replaces and enhances functions of ARP [17]. To understand which replaces and enhances functions of ARP [18]. 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 [23] 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. Terminology 4. Terminology
This sections defines terminology specific to IPv6 and DHCP used in This sections defines terminology specific to IPv6 and DHCP used in
this document. this document.
4.1. IPv6 Terminology 4.1. IPv6 Terminology
IPv6 terminology relevant to this specification from the IPv6 IPv6 terminology relevant to this specification from the IPv6
Protocol [4], IPv6 Addressing Architecture [8], and IPv6 Stateless Protocol [5], IPv6 Addressing Architecture [9], and IPv6 Stateless
Address Autoconfiguration [20] is included below. Address Autoconfiguration [21] is included below.
address An IP layer identifier for an interface address An IP layer identifier for an interface
or a set of interfaces. or a set of interfaces.
host Any node that is not a router. host Any node that is not a router.
IP Internet Protocol Version 6 (IPv6). The IP Internet Protocol Version 6 (IPv6). The
terms IPv4 and IPv6 are used only in terms IPv4 and IPv6 are used only in
contexts where it is necessary to avoid contexts where it is necessary to avoid
ambiguity. ambiguity.
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unicast address An identifier for a single interface. unicast address An identifier for a single interface.
A packet sent to a unicast address is A packet sent to a unicast address is
delivered to the interface identified by delivered to the interface identified by
that address. that address.
4.2. DHCP Terminology 4.2. DHCP Terminology
Terminology specific to DHCP can be found below. Terminology specific to DHCP can be found below.
appropriate to the link an address is "appropriate to the link" appropriate to the link An address is "appropriate to the link"
when the address is consistent with the when the address is consistent with the
DHCP server's knowledge of the network DHCP server's knowledge of the network
topology, prefix assignment and address topology, prefix assignment and address
assignment policies. assignment policies.
binding A binding (or, client binding) is a binding A binding (or, client binding) is a
group of server data records containing group of server data records containing
the information the server has about the information the server has about
the addresses in an IA or configuration the addresses in an IA or configuration
information explicitly assigned to the information explicitly assigned to the
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necessary to avoid ambiguity. necessary to avoid ambiguity.
DHCP client (or client) A node that initiates requests on a link DHCP client (or client) A node that initiates requests on a link
to obtain configuration parameters from to obtain configuration parameters from
one or more DHCP servers. one or more DHCP servers.
DHCP domain A set of links managed by DHCP and DHCP domain A set of links managed by DHCP and
operated by a single administrative operated by a single administrative
entity. entity.
DHCP realm A names used to identify the DHCP DHCP realm A name used to identify the DHCP
administrative domain from which a DHCP administrative domain from which a DHCP
authentication key was selected. authentication key was selected.
DHCP relay agent (or relay agent) A node that acts as an DHCP relay agent (or relay agent) A node that acts as an
intermediary to deliver DHCP messages intermediary to deliver DHCP messages
between clients and servers, and is on between clients and servers, and is on
the same link as the client. the same link as the client.
DHCP server (or server) A node that responds to requests from DHCP server (or server) A node that responds to requests from
clients, and may or may not be on the clients, and may or may not be on the
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all IAIDs for IAs belonging to that all IAIDs for IAs belonging to that
client. client.
Identity association for non-temporary addresses (IA_NA) An IA Identity association for non-temporary addresses (IA_NA) An IA
that carries assigned addresses that are that carries assigned addresses that are
not temporary addresses (see "identity not temporary addresses (see "identity
association for temporary addresses") association for temporary addresses")
Identity association for temporary addresses (IA_TA) An IA that Identity association for temporary addresses (IA_TA) An IA that
carries temporary addresses (see RFC carries temporary addresses (see RFC
3041 [15]). 3041 [16]).
message A unit of data carried as the payload message A unit of data carried as the payload
of a UDP datagram, exchanged among DHCP of a UDP datagram, exchanged among DHCP
servers, relay agents and clients. servers, relay agents and clients.
Reconfigure key An key supplied to a client by a server Reconfigure key An key supplied to a client by a server
used to provide security for Reconfigure used to provide security for Reconfigure
messages. messages.
relaying A DHCP relay agent relays DHCP messages relaying A DHCP relay agent relays DHCP messages
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peer-address Copied from the Relay-forward message peer-address Copied from the Relay-forward message
options MUST include a "Relay Message option"; see options MUST include a "Relay Message option"; see
section 22.10; MAY include other options section 22.10; MAY include other options
8. Representation and Use of Domain Names 8. Representation and Use of Domain Names
So that domain names may be encoded uniformly, a domain name or a So that domain names may be encoded uniformly, a domain name or a
list of domain names is encoded using the technique described in list of domain names is encoded using the technique described in
section 3.1 of RFC1035 [13]. A domain name or list of domain names section 3.1 of RFC1035 [14]. A domain name or list of domain names
in DHCP MUST NOT be stored in compressed form as described in section in DHCP MUST NOT be stored in compressed form as described in section
4.1.4 of RFC1035. 4.1.4 of RFC1035.
9. DHCP Unique Identifier (DUID) 9. DHCP Unique Identifier (DUID)
Each DHCP client and server has a DUID. DHCP servers use DUIDs to Each DHCP client and server has a DUID. DHCP servers use DUIDs to
identify clients for the selection of configuration parameters and identify clients for the selection of configuration parameters and
in the association of IAs with clients. DHCP clients use DUIDs to in the association of IAs with clients. DHCP clients use DUIDs to
identify a server in messages where a server needs to be identified. identify a server in messages where a server needs to be identified.
See sections 22.2 and 22.3 for the representation of a DUID in a DHCP See sections 22.2 and 22.3 for the representation of a DUID in a DHCP
skipping to change at page 14, line 30 skipping to change at page 14, line 30
9.2. DUID Based on Link-layer Address Plus Time [DUID-LLT] 9.2. DUID Based on Link-layer Address Plus Time [DUID-LLT]
This type of DUID consists of a two octet type field containing the This type of DUID consists of a two octet type field containing the
value 1, a two octet hardware type code, four octets containing value 1, a two octet hardware type code, four octets containing
a time value, followed by link-layer address of any one network a time value, followed by link-layer address of any one network
interface that is connected to the DHCP device at the time that the interface that is connected to the DHCP device at the time that the
DUID is generated. The time value is the time that the DUID is DUID is generated. The time value is the time that the DUID is
generated represented in seconds since midnight (UTC), January 1, generated represented in seconds since midnight (UTC), January 1,
2000, modulo 2^32. The hardware type MUST be a valid hardware type 2000, modulo 2^32. The hardware type MUST be a valid hardware type
assigned by the IANA as described in RFC826 [17]. Both the time and assigned by the IANA as described in RFC826 [18]. Both the time and
the hardware type are stored in network byte order. The link-layer the hardware type are stored in network byte order. The link-layer
address is stored in canonical form, as described in RFC2464 [3]. address is stored in canonical form, as described in RFC2464 [4].
The following diagram illustrates the format of a DUID-LLT: The following diagram illustrates the format of a DUID-LLT:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 | hardware type (16 bits) | | 1 | hardware type (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| time (32 bits) | | time (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Despite our best efforts, it is possible that this algorithm for Despite our best efforts, it is possible that this algorithm for
generating a DUID could result in a client identifier collision. generating a DUID could result in a client identifier collision.
A DHCP client that generates a DUID-LLT using this mechanism MUST A DHCP client that generates a DUID-LLT using this mechanism MUST
provide an administrative interface that replaces the existing DUID provide an administrative interface that replaces the existing DUID
with a newly-generated DUID-LLT. with a newly-generated DUID-LLT.
9.3. DUID Assigned by Vendor Based on Enterprise Number [DUID-EN] 9.3. DUID Assigned by Vendor Based on Enterprise Number [DUID-EN]
This form of DUID is assigned by the vendor to the device. It This form of DUID is assigned by the vendor to the device. It
consists of the vendor's registered Private Enterprise Number as consists of the vendor's registered Private Enterprise Number as
maintained by IANA [9] followed by a unique identifier assigned by maintained by IANA [10] followed by a unique identifier assigned by
the vendor. The following diagram summarizes the structure of a the vendor. The following diagram summarizes the structure of a
DUID-EN: DUID-EN:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2 | enterprise-number | | 2 | enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number (contd) | | | enterprise-number (contd) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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. (variable length) . . (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The source of the identifier is left up to the vendor defining it, The source of the identifier is left up to the vendor defining it,
but each identifier part of each DUID-EN MUST be unique to the device but each identifier part of each DUID-EN MUST be unique to the device
that is using it, and MUST be assigned to the device at the time of that is using it, and MUST be assigned to the device at the time of
manufacture and stored in some form of non-volatile storage. The manufacture and stored in some form of non-volatile storage. The
generated DUID SHOULD be recorded in non-erasable storage. The generated DUID SHOULD be recorded in non-erasable storage. The
enterprise-number is the vendor's registered Private Enterprise enterprise-number is the vendor's registered Private Enterprise
Number as maintained by IANA [9]. The enterprise-number is stored as Number as maintained by IANA [10]. The enterprise-number is stored
an unsigned 32 bit number. as an unsigned 32 bit number.
An example DUID of this type might look like this: An example DUID of this type might look like this:
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
| 0 | 2 | 0 | 0 | 0 | 9| 12|192| | 0 | 2 | 0 | 0 | 0 | 9| 12|192|
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
|132|221| 3 | 0 | 9 | 18| |132|221| 3 | 0 | 9 | 18|
+---+---+---+---+---+---+ +---+---+---+---+---+---+
This example includes the two-octet type of 2, the Enterprise This example includes the two-octet type of 2, the Enterprise
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(0x0CC084D303000912). (0x0CC084D303000912).
9.4. DUID Based on Link-layer Address [DUID-LL] 9.4. DUID Based on Link-layer Address [DUID-LL]
This type of DUID consists of two octets containing the DUID type 3, This type of DUID consists of two octets containing the DUID type 3,
a two octet network hardware type code, followed by the link-layer a two octet network hardware type code, followed by the link-layer
address of any one network interface that is permanently connected to address of any one network interface that is permanently connected to
the client or server device. For example, a host that has a network the client or server device. For example, a host that has a network
interface implemented in a chip that is unlikely to be removed and interface implemented in a chip that is unlikely to be removed and
used elsewhere could use a DUID-LL. The hardware type MUST be a valid used elsewhere could use a DUID-LL. The hardware type MUST be a valid
hardware type assigned by the IANA as described in RFC826 [17]. hardware type assigned by the IANA as described in RFC826 [18].
The hardware type is stored in network byte order. The link-layer The hardware type is stored in network byte order. The link-layer
address is stored in canonical form, as described in RFC2464 [3]. address is stored in canonical form, as described in RFC2464 [4].
The following diagram illustrates the format of a DUID-LL: The following diagram illustrates the format of a DUID-LL:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 3 | hardware type (16 bits) | | 3 | hardware type (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. link-layer address (variable length) . . link-layer address (variable length) .
. . . .
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same IAID as long as the configuration of the client has not changed. same IAID as long as the configuration of the client has not changed.
There may be no way for a client to maintain consistency of the IAIDs There may be no way for a client to maintain consistency of the IAIDs
if it does not have non-volatile storage and the client's hardware if it does not have non-volatile storage and the client's hardware
configuration changes. configuration changes.
The configuration information in an IA consists of one or more IPv6 The configuration information in an IA consists of one or more IPv6
addresses along with the times T1 and T2 for the IA. See section 22.4 addresses along with the times T1 and T2 for the IA. See section 22.4
for the representation of an IA in a DHCP message. for the representation of an IA in a DHCP message.
Each address in an IA has a preferred lifetime and a valid lifetime, Each address in an IA has a preferred lifetime and a valid lifetime,
as defined in RFC2462 [20]. The lifetimes are transmitted from the as defined in RFC2462 [21]. The lifetimes are transmitted from the
DHCP server to the client in the IA option. The lifetimes apply to DHCP server to the client in the IA option. The lifetimes apply to
the use of IPv6 addresses as described in section 5.5.4 of RFC2462. the use of IPv6 addresses as described in section 5.5.4 of RFC2462.
11. Selecting Addresses for Assignment to an IA 11. 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 some combination of the following sources: from some combination of the following sources:
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- 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
Any address assigned by a server that is based on an EUI-64 Any address assigned by a server that is based on an EUI-64
identifier MUST include an interface identifier with the "u" identifier MUST include an interface identifier with the "u"
(universal/local) and "g" (individual/group) bits of the interface (universal/local) and "g" (individual/group) bits of the interface
identifier set appropriately, as indicated in section 2.5.1 of RFC identifier set appropriately, as indicated in section 2.5.1 of RFC
2373 [8]. 2373 [9].
A server MUST NOT assign an address that is otherwise reserved for A server MUST NOT assign an address that is otherwise reserved for
some other purpose. For example, a server MUST NOT assign reserved some other purpose. For example, a server MUST NOT assign reserved
anycast addresses, as defined in RFC2526, from any subnet. anycast addresses, as defined in RFC2526, from any subnet.
12. Management of Temporary Addresses 12. Management of Temporary Addresses
A client may request the assignment of temporary addresses (see A client may request the assignment of temporary addresses (see
RFC 3041 [15] for the definition of temporary addresses). DHCPv6 RFC 3041 [16] for the definition of temporary addresses). DHCPv6
handling of address assignment is no different for temporary handling of address assignment is no different for temporary
addresses. DHCPv6 says nothing about details of temporary addresses addresses. DHCPv6 says nothing about details of temporary addresses
like lifetimes, how clients use temporary addresses, rules for like lifetimes, how clients use temporary addresses, rules for
generating successive temporary addresses, etc. generating successive temporary addresses, etc.
Clients ask for temporary addresses and servers assign them. Clients ask for temporary addresses and servers assign them.
Temporary addresses are carried in the Identity Association for Temporary addresses are carried in the Identity Association for
Temporary Addresses (IA_TA) option (see section 22.5). Each IA_TA Temporary Addresses (IA_TA) option (see section 22.5). Each IA_TA
option contains at most one temporary address for each of the option contains at most one temporary address for each of the
prefixes on the link to which the client is attached. prefixes on the link to which the client is attached.
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Clients and servers MUST discard any received Relay-reply messages. Clients and servers MUST discard any received Relay-reply messages.
16. Client Source Address and Interface Selection 16. Client Source Address and Interface Selection
When a client sends a DHCP message to the When a client sends a DHCP message to the
All_DHCP_Relay_Agents_and_Servers address, it SHOULD send the All_DHCP_Relay_Agents_and_Servers address, it SHOULD send the
message through the interface for which configuration information is message through the interface for which configuration information is
being requested. However, the client MAY send the message through being requested. However, the client MAY send the message through
another interface attached to the same link if and only if the another interface attached to the same link if and only if the
client is certain the two interface are attached to the same link. client is certain the two interfaces are attached to the same link.
The client MUST use a link-local address assigned to the interface The client MUST use a link-local address assigned to the interface
for which is is requesting configuration information as the source for which is is requesting configuration information as the source
address in the header of the IP datagram. address in the header of the IP datagram.
When a client sends a DHCP message directly to a server using unicast When a client sends a DHCP message directly to a server using unicast
(after receiving the Server Unicast option from that server), the (after receiving the Server Unicast option from that server), the
source address in the header of the IP datagram MUST be an address source address in the header of the IP datagram MUST be an address
assigned to the interface for which the client is interested in assigned to the interface for which the client is interested in
obtaining configuration and which is suitable for use by the server obtaining configuration and which is suitable for use by the server
in responding to the client. in responding to the client.
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addresses in the IAs as a hint to the server about addresses for addresses in the IAs as a hint to the server about addresses for
which the client has a preference. The client MUST NOT include any which the client has a preference. The client MUST NOT include any
other options in the Solicit message except as specifically allowed other options in the Solicit message except as specifically allowed
in the definition of individual options. in the definition of individual options.
The client uses IA_NA options to request the assignment of The client uses IA_NA options to request the assignment of
non-temporary addresses and uses IA_TA options to request the non-temporary addresses and uses IA_TA options to request the
assignment of temporary addresses. Either IA_NA or IA_TA options, or assignment of temporary addresses. Either IA_NA or IA_TA options, or
a combination of both can be included in DHCP messages. a combination of both can be included in DHCP messages.
The client MUST include an Option Request option (see section 22.7) The client SHOULD include an Option Request option (see section 22.7)
to indicate the options the client is interested in receiving. The to indicate the options the client is interested in receiving. The
client MAY additionally include instances of those options that are client MAY additionally include instances of those options that are
identified in the Option Request option with data values as hints identified in the Option Request option with data values as hints
to the server about parameter values the client would like to have to the server about parameter values the client would like to have
returned. returned.
The client MUST include a Reconfigure Accept option (see The client includes a Reconfigure Accept option (see section 22.20)
section 22.20) indicating whether or not the client is willing to if the client is willing to accept Reconfigure messages from the
accept Reconfigure messages from the server. server.
17.1.2. Transmission of Solicit Messages 17.1.2. Transmission of Solicit Messages
The first Solicit message from the client on the interface MUST be The first Solicit message from the client on the interface MUST be
delayed by a random amount of time between 0 and SOL_MAX_DELAY. In delayed by a random amount of time between 0 and SOL_MAX_DELAY. In
the case of a Solicit message transmitted when DHCP is initiated the case of a Solicit message transmitted when DHCP is initiated
by IPv6 Neighbor Discovery, the delay gives the amount of time to by IPv6 Neighbor Discovery, the delay gives the amount of time to
wait after IPv6 Neighbor Discovery causes the client to invoke the wait after IPv6 Neighbor Discovery causes the client to invoke the
stateful address autoconfiguration protocol (see section 5.5.3 of stateful address autoconfiguration protocol (see section 5.5.3 of
RFC2462). This random delay desynchronizes clients which start at RFC2462). This random delay desynchronizes clients which start at
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includes its server identifier in a Server Identifier option and includes its server identifier in a Server Identifier option and
copies the Client Identifier from the Solicit message into the copies the Client Identifier from the Solicit message into the
Advertise message. Advertise message.
The server MAY add a Preference option to carry the preference value The server MAY add a Preference option to carry the preference value
for the Advertise message. The server implementation SHOULD allow for the Advertise message. The server implementation SHOULD allow
the setting of a server preference value by the administrator. the setting of a server preference value by the administrator.
The server preference value MUST default to zero unless otherwise The server preference value MUST default to zero unless otherwise
configured by the server administrator. configured by the server administrator.
The server MUST add a Reconfigure Accept option to indicate whether The server includes a Reconfigure Accept option if the server wants
the client is required to accept or discard any Reconfigure messages to require that the client accept Reconfigure messages.
it receives.
The server includes options the server will return to the client in The server includes options the server will return to the client in
a subsequent Reply message. The information in these options may a subsequent Reply message. The information in these options may
be used by the client in the selection of a server if the client be used by the client in the selection of a server if the client
receives more than one Advertise message. If the client has included receives more than one Advertise message. If the client has included
an Option Request option in the Solicit message, the server includes an Option Request option in the Solicit message, the server includes
options in the Advertise message containing configuration parameters options in the Advertise message containing configuration parameters
for all of the options identified in the Option Request option for all of the options identified in the Option Request option
that the server has been configured to return to the client. The that the server has been configured to return to the client. The
server MAY return additional options to the client if it has been server MAY return additional options to the client if it has been
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Solicit-Reply message exchange will be deployed so that only Solicit-Reply message exchange will be deployed so that only
one server will respond to a Solicit message. If more than one server will respond to a Solicit message. If more than
one server responds, the client will only use the addresses one server responds, the client will only use the addresses
from one of the servers and the addresses from the other from one of the servers and the addresses from the other
servers will be committed to the client but not used by the servers will be committed to the client but not used by the
client. client.
The server includes a Rapid Commit option in the Reply message to The server includes a Rapid Commit option in the Reply message to
indicate that the Reply is in response to a Solicit message. indicate that the Reply is in response to a Solicit message.
The server MUST add a Reconfigure Accept option to indicate whether The server includes a Reconfigure Accept option if the server wants
the client is required to accept or discard any Reconfigure messages to require that the client accept Reconfigure messages.
the client receives.
The server produces the Reply message as though it had received The server produces the Reply message as though it had received
a Request message, as described in section 18.2.1. The server a Request message, as described in section 18.2.1. The server
transmits the Reply message as described in section 18.2.8. transmits the Reply message as described in section 18.2.8.
18. DHCP Client-Initiated Configuration Exchange 18. DHCP Client-Initiated Configuration Exchange
A client initiates a message exchange with a server or servers A client initiates a message exchange with a server or servers
to acquire or update configuration information of interest. The to acquire or update configuration information of interest. The
client may initiate the configuration exchange as part of the client may initiate the configuration exchange as part of the
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The client MUST include a Client Identifier option to identify itself The client MUST include a Client Identifier option to identify itself
to the server. The client adds any other appropriate options, to the server. The client adds any other appropriate options,
including one or more IA options (if the client is requesting that including one or more IA options (if the client is requesting that
the server assign it some network addresses). the server assign it some network addresses).
The client MUST include an Option Request option (see section 22.7) The client MUST include an Option Request option (see section 22.7)
to indicate the options the client is interested in receiving. The to indicate the options the client is interested in receiving. The
client MAY include options with data values as hints to the server client MAY include options with data values as hints to the server
about parameter values the client would like to have returned. about parameter values the client would like to have returned.
The client MUST include a Reconfigure Accept option (see section The client includes a Reconfigure Accept option (see section
indicating whether or not the client is willing to accept Reconfigure indicating whether or not the client is willing to accept Reconfigure
messages from the server. messages from the server.
The client transmits the message according to section 14, using the The client transmits the message according to section 14, using the
following parameters: following parameters:
IRT REQ_TIMEOUT IRT REQ_TIMEOUT
MRT REQ_MAX_RT MRT REQ_MAX_RT
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not to respond to the message at all. The client MUST include a not to respond to the message at all. The client MUST include a
Client Identifier option if the Information-Request message will be Client Identifier option if the Information-Request message will be
authenticated. authenticated.
The client MUST include an Option Request option (see section 22.7) The client MUST include an Option Request option (see section 22.7)
to indicate the options the client is interested in receiving. The to indicate the options the client is interested in receiving. The
client MAY include options with data values as hints to the server client MAY include options with data values as hints to the server
about parameter values the client would like to have returned. about parameter values the client would like to have returned.
The first Information-request message from the client on the The first Information-request message from the client on the
interface MUST be delayed by a random amount of time between 0 interface MUST be delayed by a random amount of time between 0 and
and INF_MAX_DELAY.The client transmits the message according to INF_MAX_DELAY. In the case of a Solicit message transmitted when DHCP
is initiated by IPv6 Neighbor Discovery, the delay gives the amount
of time to wait after IPv6 Neighbor Discovery causes the client to
invoke the stateful address autoconfiguration protocol (see section
5.5.3 of RFC2462). The client transmits the message according to
section 14, using the following parameters: section 14, using the following parameters:
IRT INF_TIMEOUT IRT INF_TIMEOUT
MRT INF_MAX_RT MRT INF_MAX_RT
MRC 0 MRC 0
MRD 0 MRD 0
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18.1.8. Receipt of Reply Messages 18.1.8. Receipt of Reply Messages
Upon the receipt of a valid Reply message in response to a Solicit Upon the receipt of a valid Reply message in response to a Solicit
(with a Rapid Commit option), Request, Confirm, Renew, Rebind or (with a Rapid Commit option), Request, Confirm, Renew, Rebind or
Information-request message, the client extracts the configuration Information-request message, the client extracts the configuration
information contained in the Reply. The client MAY choose to report information contained in the Reply. The client MAY choose to report
any status code or message from the status code option in the Reply any status code or message from the status code option in the Reply
message. message.
The client SHOULD perform duplicate address detection [20] on each The client SHOULD perform duplicate address detection [21] on each
of the addresses in any IAs it receives in the Reply message before of the addresses in any IAs it receives in the Reply message before
using that address for traffic. If any of the addresses are found using that address for traffic. If any of the addresses are found
to be in use on the link, the client sends a Decline message to the to be in use on the link, the client sends a Decline message to the
server as described in section 18.1.7. server as described in section 18.1.7.
If the Reply was received in response to a Solicit (with a Rapid If the Reply was received in response to a Solicit (with a Rapid
Commit option), Request, Renew or Rebind message, the client updates Commit option), Request, Renew or Rebind message, the client updates
the information it has recorded about IAs from the IA options the information it has recorded about IAs from the IA options
contained in the Reply message: contained in the Reply message:
- Record T1 and T2 times - Record T1 and T2 times
- Add any new addresses in the IA option to the IA as recorded by - Add any new addresses in the IA option to the IA as recorded by
the client the client
- Update lifetimes for any addresses in the IA option that the - Update lifetimes for any addresses in the IA option that the
client already has recorded in the IA client already has recorded in the IA
- Discard any addresses from the IA as recorded by the client that - Discard any addresses from the IA as recorded by the client that
have a lifetime of 0 in the IA Address option have a valid lifetime of 0 in the IA Address 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 22. the definition of each option, in section 22.
If the client receives a Reply message with a Status Code containing If the client receives a Reply message with a Status Code containing
UnspecFail, the server is indicating that it was unable to process UnspecFail, the server is indicating that it was unable to process
the message due to an unspecified failure condition. If the client the message due to an unspecified failure condition. If the client
retransmits the original message to the same server to retry the retransmits the original message to the same server to retry the
desired operation, the client MUST limit the rate at which it desired operation, the client MUST limit the rate at which it
retransmits the message and limit the duration of the time during retransmits the message and limit the duration of the time during
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If the server cannot assign any addresses to an IA in the message If the server cannot assign any addresses to an IA in the message
from the client, the server MUST include the IA in the Reply message from the client, the server MUST include the IA in the Reply message
with no addresses in the IA and a Status Code option in the IA with no addresses in the IA and a Status Code option in the IA
containing status code NoAddrsAvail. containing status code NoAddrsAvail.
For any IAs to which the server can assign addresses, the server For any IAs to which the server can assign addresses, the server
includes the IA with addresses and other configuration parameters and includes the IA with addresses and other configuration parameters and
records the IA as a new client binding. records the IA as a new client binding.
The server MUST add a Reconfigure Accept option to indicate whether The server includes a Reconfigure Accept option if the server wants
the client should accept any Reconfigure messages. to require that the client accept Reconfigure messages.
The server includes other options containing configuration The server includes other options containing configuration
information to be returned to the client as described in information to be returned to the client as described in
section 18.2. section 18.2.
18.2.2. Receipt of Confirm Messages 18.2.2. Receipt of Confirm Messages
When the server receives a Confirm message, the server determines if When the server receives a Confirm message, the server determines if
the addresses in the Confirm message are appropriate to the link to the addresses in the Confirm message are appropriate to the link to
which the client is attached. If all of the addresses in the Confirm which the client is attached. If all of the addresses in the Confirm
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When the server receives a Decline message via unicast from a When the server receives a Decline message via unicast from a
client to which the server has not sent a unicast option, the server client to which the server has not sent a unicast option, the server
discards the Decline message and responds with a Reply message discards the Decline message and responds with a Reply message
containing a Status Code option with value UseMulticast, a Server containing a Status Code option with value UseMulticast, a Server
Identifier option containing the server's DUID, the Client Identifier Identifier option containing the server's DUID, the Client Identifier
option from the client message and no other options. option from the client message and no other options.
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
the addresses from the IAs. The server SHOULD mark the addresses addresses from the IAs. The server ignores addresses not assigned
declined by the client so that those addresses are not assigned to to the IA (though it may choose to log an error if it finds such an
other clients, and MAY choose to make a notification that addresses address).
were declined. The server ignores addresses not assigned to the IA
(though it may choose to log an error if it finds such an address). The client has found any addresses in the Decline messages to be
already in use on its link. Therefore, the server SHOULD mark the
addresses declined by the client so that those addresses are not
assigned to other clients, and MAY choose to make a notification that
addresses were declined. Local policy on the server determines when
the addresses identified in a Decline message may be made available
for assignment.
After all the address have been processed, the server generates a After all the address have been processed, the server generates a
Reply message and includes a Status Code option with value Success, Reply message and includes a Status Code option with value Success,
a Server Identifier option with the server's DUID and a Client a Server Identifier option with the server's DUID and a Client
Identifier option with the client's DUID. For each IA in the Decline Identifier option with the client's DUID. For each IA in the Decline
message for which the server has no binding information, the server message for which the server has no binding information, the server
adds an IA option using the IAID from the Release message and adds an IA option using the IAID from the Release message and
includes a Status Code option with the value NoBinding in the IA includes a Status Code option with the value NoBinding in the IA
option. No other options are included in the IA option. option. No other options are included in the IA option.
18.2.8. Transmission of Reply Messages 18.2.8. Transmission of Reply Messages
If the original message was received directly by the server, the If the original message was received directly by the server, the
server unicasts the Reply message directly to the client using the server unicasts the Reply message directly to the client using the
address in the source address field from the IP datagram in which the address in the source address field from the IP datagram in which the
original message was received. The Reply message MUST be unicast original message was received. The Reply message MUST be unicast
through the interface on which the original message was received. through the interface on which the original message was received.
If the original message was received in a Relay-forward message, If the original message was received in a Relay-forward message,
the server constructs a Relay-reply message with the Reply message the server constructs a Relay-reply message with the Reply message
in the payload of a Relay Message option (see section!22.10). If in the payload of a Relay Message option (see section 22.10). If
the Relay-forward messages included an Interface-id option, the the Relay-forward messages included an Interface-id option, the
server copies that option to the Relay-reply message. The server server copies that option to the Relay-reply message. The server
unicasts the Relay-reply message directly to the relay agent using unicasts the Relay-reply message directly to the relay agent using
the address in the source address field from the IP datagram in which the address in the source address field from the IP datagram in which
the Relay-forward message was received. the Relay-forward message was received.
19. DHCP Server-Initiated Configuration Exchange 19. DHCP Server-Initiated Configuration Exchange
A server initiates a configuration exchange to cause DHCP clients A server initiates a configuration exchange to cause DHCP clients
to obtain new addresses and other configuration information. For to obtain new addresses and other configuration information. For
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the source and contents of DHCP messages. For example, clients may the source and contents of DHCP messages. For example, clients may
be subject to denial of service attacks through the use of bogus be subject to denial of service attacks through the use of bogus
DHCP servers, or may simply be misconfigured due to unintentionally DHCP servers, or may simply be misconfigured due to unintentionally
instantiated DHCP servers. Network administrators may wish to instantiated DHCP servers. Network administrators may wish to
constrain the allocation of addresses to authorized hosts to avoid constrain the allocation of addresses to authorized hosts to avoid
denial of service attacks in "hostile" environments where the network denial of service attacks in "hostile" environments where the network
medium is not physically secured, such as wireless networks or medium is not physically secured, such as wireless networks or
college residence halls. college residence halls.
The DHCP authentication mechanism is based on the design of The DHCP authentication mechanism is based on the design of
authentication for DHCPv4 [6]. authentication for DHCPv4 [7].
21.1. Security of Messages Sent Between Servers and Relay Agents 21.1. Security of Messages Sent Between Servers and Relay Agents
Relay agents and servers that exchange messages securely use the Relay agents and servers that exchange messages securely use the
IPsec mechanisms for IPv6 [10]. Relay agents and servers MUST IPsec mechanisms for IPv6 [11]. Relay agents and servers MUST
support manual configuration and installation of static keys. If support manual configuration and installation of static keys. If
a client message is relayed through multiple relay agents, each of a client message is relayed through multiple relay agents, each of
the relay agents must have established independent, pairwise trust the relay agents must have established independent, pairwise trust
relationships. That is, if messages from client C will be relayed by relationships. That is, if messages from client C will be relayed by
relay agent A to relay agent B and then to the server, relay agents A relay agent A to relay agent B and then to the server, relay agents A
and B must be configured to use IPSec for the messages they exchange, and B must be configured to use IPSec for the messages they exchange,
and relay agent B and the server must be configured to use IPSec for and relay agent B and the server must be configured to use IPSec for
the messages they exchange. the messages they exchange.
Relay agents and servers that support secure relay agent to server Relay agents and servers that support secure relay agent to server
or relay agent to relay agent communication, MUST include an IPsec or relay agent to relay agent communication use IPsec under the
implementation with the following restrictions: following conditions:
- The IPsec implementation MUST use ESP Selectors Relay agents are manually configured with the
addresses of the relay agent or server to which
DHCP messages are to be forwarded. Each relay
agent and server that will be using IPsec for
securing DHCP messages must also be configured
with a list of the relay agents to which messages
will be returned. The selectors for the relay
agents and servers will be the pairs of addresses
defining relay agents and servers that exchange
DHCP messages on the DHCPv6 UDP ports 546 and
547.
- Packet authentication MUST be applied Mode Relay agents and servers use transport mode and
ESP. The information in DHCP messages is not
generally considered confidential, so encryption
need not be used (i.e., NULL encryption can be
used).
- Encryption MAY be applied (i.e., NULL encryption can be used) Key management Because the relay agents and servers must be
manually configured, no automated key management
is required.
Security policy DHCP messages between relay agents and servers
should only be accepted from DHCP peers as
identified in the local configuration.
Authentication Shared keys, indexed to the source IP address of
the received DHCP message, are adequate in this
application.
Availability Appropriate IPsec implementations are likely to
be available for servers and for relay agents in
more featureful devices used in enterprise and
core ISP networks. IPsec is less likely to be
available for relay agents in low end devices
primarily used in the home or small office
markets.
21.2. Summary of DHCP Authentication 21.2. Summary of DHCP Authentication
Authentication of DHCP messages is accomplished through the use of Authentication of DHCP messages is accomplished through the use of
the Authentication option (see section 22.11). The authentication the Authentication option (see section 22.11). The authentication
information carried in the Authentication option can be used to information carried in the Authentication option can be used to
reliably identify the source of a DHCP message and to confirm that reliably identify the source of a DHCP message and to confirm that
the contents of the DHCP message have not been tampered with. the contents of the DHCP message have not been tampered with.
The Authentication option provides a framework for multiple The Authentication option provides a framework for multiple
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detection used in the replay detection field. detection used in the replay detection field.
21.3. Replay Detection 21.3. Replay Detection
The Replay Detection Method (RDM) field determines the type of replay The Replay Detection Method (RDM) field determines the type of replay
detection used in the Replay Detection field. detection used in the Replay Detection field.
If the RDM field contains 0x00, the replay detection field MUST If the RDM field contains 0x00, the replay detection field MUST
be set to the value of a monotonically increasing counter. Using be set to the value of a monotonically increasing counter. Using
a counter value such as the current time of day (for example, an a counter value such as the current time of day (for example, an
NTP-format timestamp [12]) can reduce the danger of replay attacks. NTP-format timestamp [13]) can reduce the danger of replay attacks.
This method MUST be supported by all protocols. This method MUST be supported by all protocols.
21.4. Delayed Authentication Protocol 21.4. Delayed Authentication Protocol
If the protocol field is 2, the message is using the "delayed If the protocol field is 2, the message is using the "delayed
authentication" mechanism. In delayed authentication, the client authentication" mechanism. In delayed authentication, the client
requests authentication in its Solicit message and the server replies requests authentication in its Solicit message and the server replies
with an Advertise message that includes authentication information. with an Advertise message that includes authentication information.
This authentication information contains a nonce value generated by This authentication information contains a nonce value generated by
the source as a message authentication code (MAC) to provide message the source as a message authentication code (MAC) to provide message
authentication and entity authentication. authentication and entity authentication.
The use of a particular technique based on the HMAC protocol [11] The use of a particular technique based on the HMAC protocol [12]
using the MD5 hash [19] is defined here. using the MD5 hash [20] is defined here.
21.4.1. Use of the Authentication Option in the Delayed Authentication 21.4.1. Use of the Authentication Option in the Delayed Authentication
Protocol Protocol
In a Solicit message, the client fills in the protocol, algorithm In a Solicit message, the client fills in the protocol, algorithm
and RDM fields in the Authentication option with the client's and RDM fields in the Authentication option with the client's
preferences. The client sets the replay detection field to zero and preferences. The client sets the replay detection field to zero and
omits the authentication information field. The client sets the omits the authentication information field. The client sets the
option-len field to 11. option-len field to 11.
In all other messages, the protocol and algorithm fields identifies In all other messages, the protocol and algorithm fields identifies
the method used to construct the contents of the authentication the method used to construct the contents of the authentication
information field. The RDM field identifies the method used to information field. The RDM field identifies the method used to
construct the contents of the replay detection field. The format of construct the contents of the replay detection field.
the Authentication information is:
The format of the Authentication information is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DHCP realm | | DHCP realm |
| (variable length) | | (variable length) |
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| key ID | | key ID |
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| (128 bits) | | (128 bits) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DHCP realm The DHCP realm that identifies the key used to DHCP realm The DHCP realm that identifies the key used to
generate the HMAC-MD5 value generate the HMAC-MD5 value
key ID The key identifier that identified the key used to key ID The key identifier that identified the key used to
generate the HMAC-MD5 value generate the HMAC-MD5 value
HMAC-MD5 The message signature generated by applying MD5 to HMAC-MD5 The message authentication code generated by applying
the DHCP message using the key identified by the DHCP MD5 to the DHCP message using the key identified by
realm, client DUID and key ID the DHCP realm, client DUID and key ID
The sender computes the MAC using the HMAC generation algorithm [11] The sender computes the MAC using the HMAC generation algorithm [12]
and the MD5 hash function [19]. The entire DHCP message (setting and the MD5 hash function [20]. The entire DHCP message (setting
the MAC field of the authentication option to zero), including the the MAC field of the authentication option to zero), including the
DHCP message header and the options field, is used as input to the DHCP message header and the options field, is used as input to the
HMAC-MD5 computation function. HMAC-MD5 computation function.
DISCUSSION: DISCUSSION:
Algorithm 1 specifies the use of HMAC-MD5. Use of a Algorithm 1 specifies the use of HMAC-MD5. Use of a
different technique, such as HMAC-SHA, will be specified as different technique, such as HMAC-SHA, will be specified as
a separate protocol. a separate protocol.
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administrative domains. administrative domains.
21.4.2. Message Validation 21.4.2. Message Validation
Any DHCP message that includes more than one authentication option Any DHCP message that includes more than one authentication option
MUST be discarded. MUST be discarded.
To validate an incoming message, the receiver first checks that To validate an incoming message, the receiver first checks that
the value in the replay detection field is acceptable according to the value in the replay detection field is acceptable according to
the replay detection method specified by the RDM field. Next, the the replay detection method specified by the RDM field. Next, the
receiver computes the MAC as described in [11]. The entire DHCP receiver computes the MAC as described in [12]. The entire DHCP
message (setting the MAC field of the authentication option to 0), message (setting the MAC field of the authentication option to 0),
is used as input to the HMAC-MD5 computation function. If the MAC is used as input to the HMAC-MD5 computation function. If the MAC
computed by the receiver does not match the MAC contained in the computed by the receiver does not match the MAC contained in the
authentication option, the receiver MUST discard the DHCP message. authentication option, the receiver MUST discard the DHCP message.
21.4.3. Key Utilization 21.4.3. Key Utilization
Each DHCP client has a set of keys. Each key is identifier by <DHCP Each DHCP client has a set of keys. Each key is identifier by <DHCP
realm, client DUID, key id>. Each key also has a lifetime. The key realm, client DUID, key id>. Each key also has a lifetime. The key
may not be used past the end of its lifetime. The client's keys may not be used past the end of its lifetime. The client's keys
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Note that an IA_NA has no explicit "lifetime" or "lease length" of Note that an IA_NA has no explicit "lifetime" or "lease length" of
its own. When the valid lifetimes of all of the addresses in an its own. When the valid lifetimes of all of the addresses in an
IA_NA have expired, the IA_NA can be considered as having expired. IA_NA have expired, the IA_NA can be considered as having expired.
T1 and T2 are included to give servers explicit control over when a T1 and T2 are included to give servers explicit control over when a
client recontacts the server about a specific IA_NA. client recontacts the server about a specific IA_NA.
In a message sent by a client to a server, values in the T1 and T2 In a message sent by a client to a server, values in the T1 and T2
fields indicate the client's preference for those parameters. The fields indicate the client's preference for those parameters. The
client sets T1 and T2 to 0 if it has no preference for those values. client sets T1 and T2 to 0 if it has no preference for those values.
In a message sent by a server to a client, the client MUST use the In a message sent by a server to a client, the client MUST use the
values in the T1 and T2 fields for the T1 and T2 parameters. The values in the T1 and T2 fields for the T1 and T2 parameters, unless
values in the T1 and T2 fields are the number of seconds until T1 and those values in those fields are 0. The values in the T1 and T2
T2. fields are the number of seconds until T1 and T2.
The server selects the T1 and T2 times to allow the client to extend The server selects the T1 and T2 times to allow the client to extend
the lifetimes of any addresses in the IA_NA before the lifetimes the lifetimes of any addresses in the IA_NA before the lifetimes
expire, even if the server is unavailable for some short period of expire, even if the server is unavailable for some short period of
time. Recommended values for T1 and T2 are .5 and .8 times the time. Recommended values for T1 and T2 are .5 and .8 times the
shortest preferred lifetime of the addresses in the IA, respectively. shortest preferred lifetime of the addresses in the IA, respectively.
If the time at which the addresses in an IA_NA are to be renewed is If the time at which the addresses in an IA_NA are to be renewed is
to be left to the discretion of the client, the server sets T1 and T2 to be left to the discretion of the client, the server sets T1 and T2
to 0. to 0.
22.5. Identity Association for Temporary Addresses Option 22.5. Identity Association for Temporary Addresses Option
The Identity Association for Temporary Addresses (IA_TA) option is The Identity Association for Temporary Addresses (IA_TA) option is
used to carry an IA_TA, the parameters associated with the IA_TA and used to carry an IA_TA, the parameters associated with the IA_TA and
the addresses associated with the IA_TA. All of the addresses in this the addresses associated with the IA_TA. All of the addresses in this
option are used by the client as temporary addresses, as defined in option are used by the client as temporary addresses, as defined in
RFC 3041 [15]. The format of the IA_TA option is: RFC 3041 [16]. The format of the IA_TA option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_TA | option-len | | OPTION_IA_TA | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) | | IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. IA_TA-options . . IA_TA-options .
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In a message sent by a client to a server, values in the preferred In a message sent by a client to a server, values in the preferred
and valid lifetime fields indicate the client's preference for those and valid lifetime fields indicate the client's preference for those
parameters. The client may send 0 if it has no preference for the parameters. The client may send 0 if it has no preference for the
preferred and valid lifetimes. In a message sent by a server to a preferred and valid lifetimes. In a message sent by a server to a
client, the client MUST use the values in the preferred and valid client, the client MUST use the values in the preferred and valid
lifetime fields for the preferred and valid lifetimes. The values in lifetime fields for the preferred and valid lifetimes. The values in
the preferred and valid lifetimes are the number of seconds remaining the preferred and valid lifetimes are the number of seconds remaining
in each lifetime. in each lifetime.
An IA Address option may appear only in an IA option or an IA_TA An IA Address option may appear only in an IA option or an IA_TA
option. More than one IA Address Options can appear in an IA option option. More than one IA Address Option can appear in an IA option
or an IA_TA option. or an IA_TA option.
The status of any operations involving this IA Address is indicated The status of any operations involving this IA Address is indicated
in a Status Code option in the IAaddr-options field. in a Status Code option in the IAaddr-options field.
22.7. Option Request Option 22.7. Option Request Option
The Option Request option is used to identify a list of options in The Option Request option is used to identify a list of options in
a message between a client and a server. The format of the Option a message between a client and a server. The format of the Option
Request option is: Request option is:
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server-address The IP address to which the client should send server-address The IP address to which the client should send
messages delivered using unicast messages delivered using unicast
The server specifies the IPv6 address to which the client is to send The server specifies the IPv6 address to which the client is to send
unicast messages in the server-address field. When a client receives unicast messages in the server-address field. When a client receives
this option, where permissible and appropriate, the client sends this option, where permissible and appropriate, the client sends
messages directly to the server using the IPv6 address specified in messages directly to the server using the IPv6 address specified in
the server-address field of the option. the server-address field of the option.
When the server sends a Unicast option to the client, some messages
from the client will not be relayed by Relay Agents, and will not
include Relay Agent options from the Relay Agents. Therefore, a
server should only send a Unicast option to a client when Relay
Agents are not sending Relay Agent options. A DHCP server rejects
any messages sent inappropriately using unicast to ensure that
messages are relayed by Relay Agents when Relay Agent optinos are in
use.
Details about when the client may send messages to the server using Details about when the client may send messages to the server using
unicast are in section 18. unicast are in section 18.
22.13. Status Code Option 22.13. Status Code Option
This option returns a status indication related to the DHCP message This option returns a status indication related to the DHCP message
or option in which it appears. The format of the Status Code option or option in which it appears. The format of the Status Code option
is: is:
0 1 2 3 0 1 2 3
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null-terminated. null-terminated.
A Status Code option may appear in the options field of a DHCP A Status Code option may appear in the options field of a DHCP
message and/or in the options field of another option. If the Status message and/or in the options field of another option. If the Status
Code option does not appear in a message in which the option could Code option does not appear in a message in which the option could
appear, the status of the message is assumed to be Success. appear, the status of the message is assumed to be Success.
22.14. Rapid Commit Option 22.14. Rapid Commit Option
The Rapid Commit option is used to signal the use of the two message The Rapid Commit option is used to signal the use of the two message
exchange for address assignment. exchange for address assignment. The format of the Rapid Commit
option is:
The format of the Rapid Commit option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RAPID_COMMIT | 0 | | OPTION_RAPID_COMMIT | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_RAPID_COMMIT (14) option-code OPTION_RAPID_COMMIT (14)
option-len 0 option-len 0
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the client. the client.
The problem of unused addresses can be minimized, for The problem of unused addresses can be minimized, for
example, by designing the DHCP service so that only one example, by designing the DHCP service so that only one
server responds to the Solicit or by using relatively short server responds to the Solicit or by using relatively short
lifetimes for assigned addresses. lifetimes for assigned addresses.
22.15. User Class Option 22.15. User Class Option
The User Class option is used by a client to identify the type or The User Class option is used by a client to identify the type or
category of user or applications it represents. The format of the category of user or applications it represents.
User Class option is:
The format of the User Class option is:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_USER_CLASS | option-len | | OPTION_USER_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. user-class-data . . user-class-data .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_USER_CLASS (15) option-code OPTION_USER_CLASS (15)
option-len Length of user class data field option-len Length of user class data field
user-class-data The user classes carried by the client. user-class-data The user classes carried by the client.
The information contained in the data area of this option is The information contained in the data area of this option is
contained in one or more opaque fields that represent the user contained in one or more opaque fields that represent the user
class or classes of which the client is a member. A server selects class or classes of which the client is a member. A server selects
configuration information for the client based on the classes configuration information for the client based on the classes
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includes a User Class option containing those classes that were includes a User Class option containing those classes that were
successfully interpreted by the server, so that the client can be successfully interpreted by the server, so that the client can be
informed of the classes interpreted by the server. informed of the classes interpreted by the server.
22.16. Vendor Class Option 22.16. Vendor Class Option
This option is used by a client to identify the vendor that This option is used by a client to identify the vendor that
manufactured the hardware on which the client is running. The manufactured the hardware on which the client is running. The
information contained in the data area of this option is contained information contained in the data area of this option is contained
in one or more opaque fields that identify details of the hardware in one or more opaque fields that identify details of the hardware
configuration. configuration. The format of the Vendor Class option is:
The format of the Vendor Class option is:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_VENDOR_CLASS | option-len | | OPTION_VENDOR_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number | | enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. vendor-class-data . . vendor-class-data .
. . . . . . . . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_VENDOR_CLASS (16) option-code OPTION_VENDOR_CLASS (16)
option-len 4 + length of vendor class data field option-len 4 + length of vendor class data field
enterprise-number The vendor's registered Enterprise Number as enterprise-number The vendor's registered Enterprise Number as
registered with IANA [9]. registered with IANA [10].
vendor-class-data The hardware configuration of the host on vendor-class-data The hardware configuration of the host on
which the client is running. which the client is running.
The vendor-class-data is composed of a series of separate items, The vendor-class-data is composed of a series of separate items,
each of which describes some characteristic of the client's hardware each of which describes some characteristic of the client's hardware
configuration. Examples of vendor-class-data instances might include configuration. Examples of vendor-class-data instances might include
the version of the operating system the client is running or the the version of the operating system the client is running or the
amount of memory installed on the client. amount of memory installed on the client.
skipping to change at page 73, line 23 skipping to change at page 74, line 23
. . . .
. option-data . . option-data .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_VENDOR_OPTS (17) option-code OPTION_VENDOR_OPTS (17)
option-len 4 + length of option-data field option-len 4 + length of option-data field
enterprise-number The vendor's registered Enterprise Number as enterprise-number The vendor's registered Enterprise Number as
registered with IANA [9]. registered with IANA [10].
option-data An opaque object of option-len octets, option-data An opaque object of option-len octets,
interpreted by vendor-specific code on the interpreted by vendor-specific code on the
clients and servers clients and servers
The definition of the information carried in this option is vendor The definition of the information carried in this option is vendor
specific. The vendor is indicated in the enterprise-number field. specific. The vendor is indicated in the enterprise-number field.
Use of vendor-specific information allows enhanced operation, Use of vendor-specific information allows enhanced operation,
utilizing additional features in a vendor's DHCP implementation. utilizing additional features in a vendor's DHCP implementation.
A DHCP client that does not receive requested vendor-specific A DHCP client that does not receive requested vendor-specific
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use of a "DHCP realm" in the shared key allows identification of use of a "DHCP realm" in the shared key allows identification of
administrative domains so that a client can select the appropriate administrative domains so that a client can select the appropriate
key or keys when roaming between administrative domains. However, key or keys when roaming between administrative domains. However,
the Delayed Authentication protocol does not define any mechanism the Delayed Authentication protocol does not define any mechanism
for sharing of keys, so a client may require separate keys for each for sharing of keys, so a client may require separate keys for each
administrative domain it encounters. The use of shared keys may not administrative domain it encounters. The use of shared keys may not
scale well and does not provide for repudiation of compromised keys. scale well and does not provide for repudiation of compromised keys.
This protocol is focused on solving the intradomain problem where the This protocol is focused on solving the intradomain problem where the
out-of-band exchange of a shared key is feasible. out-of-band exchange of a shared key is feasible.
Because of the opportunity for attack through the Reconfigure
message, a DHCP client MUST discard any Reconfigure message that
does not include authentication or that does not pass the validation
process for the authentication protocol.
The Reconfigure Key protocol described in section 21.5 provides The Reconfigure Key protocol described in section 21.5 provides
protection against use of a Reconfigure message by a malicious DHCP protection against use of a Reconfigure message by a malicious DHCP
server to mount a denial of service or man-in-the-middle attack on a server to mount a denial of service or man-in-the-middle attack on
client. a client. This protocol can be compromised by an attacker that can
intercept the initial message in which the DHCP server sends the key
to the client.
Communication between a server and a relay agent and communication Communication between a server and a relay agent and communication
between relay agents can be secured through the use of IPSec, as between relay agents can be secured through the use of IPSec, as
described in section 21.1. The use of manual configuration and described in section 21.1. The use of manual configuration and
installation of static keys are acceptable in this instance because installation of static keys are acceptable in this instance because
relay agents and the server will belong to the same administrative relay agents and the server will belong to the same administrative
domain and the relay agents will require other specific configuration domain and the relay agents will require other specific configuration
(for example, configuration of the DHCP server address) as well as (for example, configuration of the DHCP server address) as well as
the IPSec configuration. the IPSec configuration.
skipping to change at page 77, line 49 skipping to change at page 79, line 4
domain and the relay agents will require other specific configuration domain and the relay agents will require other specific configuration
(for example, configuration of the DHCP server address) as well as (for example, configuration of the DHCP server address) as well as
the IPSec configuration. the IPSec configuration.
24. IANA Considerations 24. IANA Considerations
This document defines several new name spaces associated with DHCPv6 This document defines several new name spaces associated with DHCPv6
and DHCPv6 options: and DHCPv6 options:
- Message types - Message types
- Status codes - Status codes
- DUID - DUID
- Option codes - Option codes
IANA is requested to manage a registry of values for each of these IANA is requested to manage a registry of values for each of these
name spaces, which are described in the remainder of this section. name spaces, which are described in the remainder of this section.
These name spaces are all to be managed separately from the name These name spaces are all to be managed separately from the name
spaces defined for DHCPv4. spaces defined for DHCPv4.
New multicast addresses, message types, status codes and DUID types New multicast addresses, message types, status codes and DUID types
are assigned via Standards Action [14]. are assigned via Standards Action [15].
New DHCP option codes are tentatively assigned after the New DHCP option codes are tentatively assigned after the
specification for the associated option, published as an Internet specification for the associated option, published as an Internet
Draft, has received expert review by a designated expert [14]. The Draft, has received expert review by a designated expert [15]. The
final assignment of DHCP option codes is through Standards Action, as final assignment of DHCP option codes is through Standards Action, as
defined in RFC2434 [14]. defined in RFC2434 [15].
This document also references three name spaces in section 21 that This document also references three name spaces in section 21 that
are associated with the Authentication Option (section 22.11). These are associated with the Authentication Option (section 22.11). These
name spaces are defined by the authentication mechanism for DHCPv4 in name spaces are defined by the authentication mechanism for DHCPv4 in
RFC3118 [6]. RFC3118 [7].
The authentication name spaces currently registered by IANA will The authentication name spaces currently registered by IANA will
apply to both DHCPv6 and DHCPv4. In the future, specifications that apply to both DHCPv6 and DHCPv4. In the future, specifications that
define new Protocol, Algorithm and RDM mechanisms will explicitly define new Protocol, Algorithm and RDM mechanisms will explicitly
define whether the new mechanisms are used with DHCPv4, DHCPv6 or define whether the new mechanisms are used with DHCPv4, DHCPv6 or
both. both.
24.1. Multicast Addresses 24.1. Multicast Addresses
Section 5.1 defines the following multicast addresses, which have Section 5.1 defines the following multicast addresses, which have
skipping to change at page 81, line 4 skipping to change at page 82, line 12
DUID-LL 3 DUID-LL 3
25. Acknowledgments 25. Acknowledgments
Thanks to the DHC Working Group and the members of the IETF for Thanks to the DHC Working Group and the members of the IETF for
their time and input into the specification. In particular, thanks their time and input into the specification. In particular, thanks
also for the consistent input, ideas, and review by (in alphabetical also for the consistent input, ideas, and review by (in alphabetical
order) Bernard Aboba, Bill Arbaugh, Thirumalesh Bhat, Steve Bellovin, order) Bernard Aboba, Bill Arbaugh, Thirumalesh Bhat, Steve Bellovin,
A. K. Vijayabhaskar, Brian Carpenter, Matt Crawford, Francis Dupont, A. K. Vijayabhaskar, Brian Carpenter, Matt Crawford, Francis Dupont,
Kim Kinnear, Fredrik Lindholm, Tony Lindstrom, Josh Littlefield, Richard Hussong, Kim Kinnear, Fredrik Lindholm, Tony Lindstrom, Josh
Gerald Maguire, Jack McCann, Shin Miyakawa, Thomas Narten, Erik Littlefield, Gerald Maguire, Jack McCann, Shin Miyakawa, Thomas
Nordmark, Jarno Rajahalme, Yakov Rekhter, Mark Stapp, Matt Thomas, Narten, Erik Nordmark, Jarno Rajahalme, Yakov Rekhter, Mark Stapp,
Sue Thomson, Tatuya Jinmei and Phil Wells. Matt Thomas, Sue Thomson, Tatuya Jinmei 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.
And, thanks to Steve Deering for pointing out at IETF 51 in London And, thanks to Steve Deering for pointing out at IETF 51 in London
that the DHCPv6 specification has the highest revision number of any that the DHCPv6 specification has the highest revision number of any
Internet Draft. Internet Draft.
26. Changes in draft-ietf-dhc-dhcpv6-27.txt 26. Changes in draft-ietf-dhc-dhcpv6-27.txt
skipping to change at page 82, line 26 skipping to change at page 83, line 31
- Reconfigure message includes IA option to specifically identify - Reconfigure message includes IA option to specifically identify
IAs that are to be modified. IAs that are to be modified.
- Reconfigure Accept option allows client to tell server if it - Reconfigure Accept option allows client to tell server if it
will do Reconfigure and allows server to control whether client will do Reconfigure and allows server to control whether client
accepts Reconfigure accepts Reconfigure
- Use of Reconfigure Key message is a new protocol in DHCP - Use of Reconfigure Key message is a new protocol in DHCP
authentication authentication
27. Changes in draft-ietf-dhc-dhcpv6-28.txt
- Added sentence to next to last paragraph of section 23, noting
that the Reconfigure Ksy protocol can be compromised by an
attacker that can intercept the key sent from the server to the
client.
- Added paragraph emphasizing that a client MUST discard any
Reconfigure message that is not authenticated or does not pass
authentication.
- Added paragraph to section 18.2.7 clarifying that the client has
included the address in a Decline message because it found that
the address is already in use, and that the server should not
reuse the address as allowed by local policy.
- Added paragraph to section 22.12 clarifying that use of the
Unicast option precludes use of Relay Agent options, and that a
server discards unicast messages when the Unicast option has not
been sent, to ensure use of Relay Agent options.
- Edited section 21.1 to describe the use of ipsec according to
"Guidelines for Mandating the Use of IPsec" [2].
- Changed "MUST..." to "SHOULD include an Option Request option" in
section 17.1.1, to match description in section 22.7 of when a
client uses the option.
- Edited sections 17.1.1, 17.2.2, 17.2.3, 18.1.1 and 18.2.1
to match the definition of the Reconfigure Accept option in
section 22.20.
- Added text to section 18.1.5 specifying that delay of first
message is measured from receipt of router advertisement.
References References
[1] S. Alexander and R. Droms. DHCP Options and BOOTP Vendor [1] S. Alexander and R. Droms. DHCP Options and BOOTP Vendor
Extensions, March 1997. RFC 2132. Extensions, March 1997. RFC 2132.
[2] S. Bradner. Key words for use in RFCs to Indicate Requirement [2] S. Bellovin. Guidelines for Mandating the Use of IPsec, October
2002. work in progress.
[3] S. Bradner. Key words for use in RFCs to Indicate Requirement
Levels, March 1997. RFC 2119. Levels, March 1997. RFC 2119.
[3] M. Crawford. Transmission of IPv6 Packets over Ethernet [4] M. Crawford. Transmission of IPv6 Packets over Ethernet
Networks, December 1998. RFC 2464. Networks, December 1998. RFC 2464.
[4] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6) [5] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6)
Specification, December 1998. RFC 2460. Specification, December 1998. RFC 2460.
[5] R. Droms. Dynamic Host Configuration Protocol, March 1997. RFC [6] R. Droms. Dynamic Host Configuration Protocol, March 1997. RFC
2131. 2131.
[6] R. Droms, Editor, W. Arbaugh, and Editor. Authentication for [7] R. Droms, Editor, W. Arbaugh, and Editor. Authentication for
DHCP Messages, June 2001. RFC 3118. DHCP Messages, June 2001. RFC 3118.
[7] R. (ed.) Droms. DNS Configuration options for DHCPv6. Internet [8] R. (ed.) Droms. DNS Configuration options for DHCPv6. Internet
Draft, Internet Engineering Task Force, April 2002. Work in Draft, Internet Engineering Task Force, April 2002. Work in
progress. progress.
[8] R. Hinden and S. Deering. IP Version 6 Addressing Architecture, [9] R. Hinden and S. Deering. IP Version 6 Addressing Architecture,
July 1998. RFC 2373. July 1998. RFC 2373.
[9] IANA. Private Enterprise Numbers. [10] IANA. Private Enterprise Numbers.
http://www.iana.org/assignments/enterprise-numbers.html. http://www.iana.org/assignments/enterprise-numbers.html.
[10] S. Kent and R. Atkinson. Security Architecture for the Internet [11] S. Kent and R. Atkinson. Security Architecture for the Internet
Protocol, November 1998. RFC 2401. Protocol, November 1998. RFC 2401.
[11] H. Krawczyk, M. Bellare, and R. Canetti. HMAC: Keyed-Hashing [12] H. Krawczyk, M. Bellare, and R. Canetti. HMAC: Keyed-Hashing
for Message Authentication, February 1997. RFC 2104. for Message Authentication, February 1997. RFC 2104.
[12] David L. Mills. Network Time Protocol (Version 3) [13] David L. Mills. Network Time Protocol (Version 3)
Specification, Implementation, March 1992. RFC 1305. Specification, Implementation, March 1992. RFC 1305.
[13] P.V. Mockapetris. Domain names - implementation and [14] P.V. Mockapetris. Domain names - implementation and
specification, November 1987. RFC 1035. specification, November 1987. RFC 1035.
[14] T. Narten and H. Alvestrand. Guidelines for Writing an IANA [15] T. Narten and H. Alvestrand. Guidelines for Writing an IANA
Considerations Section in RFCs, October 1998. RFC 2434. Considerations Section in RFCs, October 1998. RFC 2434.
[15] T. Narten and R. Draves. Privacy Extensions for Stateless [16] T. Narten and R. Draves. Privacy Extensions for Stateless
Address Autoconfiguration in IPv6, January 2001. RFC 3041. Address Autoconfiguration in IPv6, January 2001. RFC 3041.
[16] T. Narten, E. Nordmark, and W. Simpson. Neighbor Discovery for [17] T. Narten, E. Nordmark, and W. Simpson. Neighbor Discovery for
IP Version 6 (IPv6), December 1998. RFC 2461. IP Version 6 (IPv6), December 1998. RFC 2461.
[17] D.C. Plummer. Ethernet Address Resolution Protocol: Or [18] D.C. Plummer. Ethernet Address Resolution Protocol: Or
converting network protocol addresses to 48.bit Ethernet address converting network protocol addresses to 48.bit Ethernet address
for transmission on Ethernet hardware, November 1982. RFC 826. for transmission on Ethernet hardware, November 1982. RFC 826.
[18] J. Postel. User Datagram Protocol, August 1980. RFC 768. [19] J. Postel. User Datagram Protocol, August 1980. RFC 768.
[19] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC [20] R. Rivest. The MD5 Message-Digest Algorithm, April 1992. RFC
1321. 1321.
[20] S. Thomson and T. Narten. IPv6 Stateless Address [21] S. Thomson and T. Narten. IPv6 Stateless Address
Autoconfiguration, December 1998. RFC 2462. Autoconfiguration, December 1998. RFC 2462.
[21] A. K. Vijayabhaskar. Time Configuration Options for DHCPv6. [22] A. K. Vijayabhaskar. Time Configuration Options for DHCPv6.
Internet Draft, Internet Engineering Task Force, May 2002. Work Internet Draft, Internet Engineering Task Force, May 2002. Work
in progress. in progress.
[22] P. Vixie, Ed., S. Thomson, Y. Rekhter, and J. Bound. Dynamic [23] 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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