draft-ietf-dhc-dhcpv6-stateless-01.txt   draft-ietf-dhc-dhcpv6-stateless-02.txt 
Network Working Group R. Droms Network Working Group R. Droms
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Expires: April 5, 2004 October 6, 2003 Expires: May 25, 2004 November 25, 2003
A Guide to Implementing Stateless DHCPv6 Service A Guide to Implementing Stateless DHCPv6 Service
draft-ietf-dhc-dhcpv6-stateless-01.txt draft-ietf-dhc-dhcpv6-stateless-02.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on April 5, 2004. This Internet-Draft will expire on May 25, 2004.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
Stateless DHCPv6 service is used by nodes to obtain configuration Stateless DHCPv6 service is used by nodes to obtain configuration
information such as the addresses of DNS recursive name servers that information such as the addresses of DNS recursive name servers that
does not require the maintenance of any dynamic state for individual does not require the maintenance of any dynamic state for individual
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"Stateless DHCP" refers to the use of DHCP to provide configuration "Stateless DHCP" refers to the use of DHCP to provide configuration
information to clients that does not require the server to maintain information to clients that does not require the server to maintain
dynamic state about the DHCP clients. dynamic state about the DHCP clients.
3. Overview 3. Overview
This document assumes that a node using stateless DHCP configuration This document assumes that a node using stateless DHCP configuration
is not using DHCP for address assignment, and that a node has is not using DHCP for address assignment, and that a node has
determined at least a link-local address as described in section 5.3 determined at least a link-local address as described in section 5.3
of RFC2461 [5] of RFC2461 [4]
To obtain configuration parameters through stateless DHCP, a node To obtain configuration parameters through stateless DHCP, a node
uses the DHCP Information-request message. DHCP servers respond to uses the DHCP Information-request message. DHCP servers respond to
the node's message with a Reply message that carries the DNS the node's message with a Reply message that carries configuration
configuration parameters. The Reply message from the server can parameters for the node. The Reply message from the server can carry
carry configuration information such as a list of DNS recursive name configuration information such as a list of DNS recursive name
servers and SIP servers. servers [3] and SIP servers [5].
This document does not apply to the function of DHCPv6 relay agents
as described in RFC 3315. A network element can provide both DHCPv6
server and DHCPv6 relay service. For example, a network element can
provide stateless DHCPv6 service to hosts requesting stateless DHCP
service, while relaying messages from hosts requesting address
assignment through DHCPv6 to another DHCPv6 server.
4. Basic Requirements for Implementation of DHCP 4. Basic Requirements for Implementation of DHCP
Several sections of the DHCP specification provide background Several sections of the DHCP specification provide background
information or define parts of the specification that are common to information or define parts of the specification that are common to
all implementations: all implementations:
1-4: give an introduction to DHCPv6 and an overview of DHCP message 1-4: give an introduction to DHCPv6 and an overview of DHCP message
flows flows
5: defines constants used throughout the protocol specification 5: defines constants used throughout the protocol specification
6, 7: illustrates the format of DHCP messages 6, 7: illustrates the format of DHCP messages
8: describes the representation of Domain Names 8: describes the representation of Domain Names
9: defines the "DHCP unique identifier" (DUID) optionally used to 9: defines the "DHCP unique identifier" (DUID)
identify DHCP participants
13-16: describe DHCP message transmission, retransmission and 13-16: describe DHCP message transmission, retransmission and
validation validation
21: describes authentication for DHCP 21: describes authentication for DHCP
5. Implementation of stateless DHCP 5. Implementation of Stateless DHCP
The client indicates that it is requesting configuration information The client indicates that it is requesting configuration information
by sending an Information-request message that includes an Option by sending an Information-request message that includes an Option
Request option specifying the options that it wishes to receive from Request option specifying the options that it wishes to receive from
the DHCP server. For example, if the client is attempting to obtain the DHCP server. For example, if the client is attempting to obtain
DNS configuration information, it includes either or both of the DNS a list of DNS recursive name servers, it identifier the DNS Recursive
configuration options in the Information-request message. The server Name Server option in the Information-request message. The server
determines the appropriate configuration parameters for the client determines the appropriate configuration parameters for the client
based on its configuration policies and responds with a Reply message based on its configuration policies and responds with a Reply message
containing the requested parameters. In this example, the server containing the requested parameters. In this example, the server
would respond with DNS configuration parameters. would respond with DNS configuration parameters.
A node uses the Client Identifier option to identify itself to a A node uses the Client Identifier option to identify itself to a
server, because the server administrator may want to customize the server, because the server administrator may want to customize the
server's response to each node, based on the node's identity. server's response to each node, based on the node's identity.
5.1 Messages required for stateless DHCP Whenever a client may have moved to a new link, the configuration
parameters obtained for the interfaces on that link may no longer be
appropriate for the link to which the client is attached. Examples
of times when a client may have moved to a new link include:
o The client reboots.
o The client is physically connected to a wired connection.
o The client returns from sleep mode.
o The client using a wireless technology changes access points.
In any situation when a client may have moved to a new link, the
client initiates an Information-request/Reply message exchange.
5.1 Messages Required for Stateless DHCP Service
Clients and servers implement the following messages for stateless Clients and servers implement the following messages for stateless
DHCP service; the section numbers in this list refer to the DHCPv6 DHCP service; the section numbers in this list refer to the DHCPv6
specification: specification:
Information-request: sent by a DHCP client to a server to request DNS Information-request: sent by a DHCP client to a server to request
configuration parameters (sections 18.1.5 and 18.2.5) configuration parameters (sections 18.1.5 and 18.2.5)
Reply: sent by a DHCP server to a client containing the Reply: sent by a DHCP server to a client containing
DNS configuration parameters (sections 18.2.6 and 18.2.8) configuration parameters (sections 18.2.6 and 18.2.8)
In addition, servers and relay agents implement the following In addition, servers and relay agents implement the following
messages for stateless DHCP service: messages for stateless DHCP service; the section numbers in this list
refer to the DHCPv6 specification:
Relay-forward: Sent by a DHCP relay agent to carry the client message Relay-forward: Sent by a DHCP relay agent to carry the client message
to a server (section 15.13) to a server (section 15.13)
Relay-reply: Sent by a DHCP server to carry a response message to Relay-reply: Sent by a DHCP server to carry a response message to
the relay agent (section 15.14) the relay agent (section 15.14)
5.2 Options required for stateless DHCP service 5.2 Options Required for Stateless DHCP Service
Clients and servers implement the following options for stateless Clients and servers implement the following options for stateless
DHCP service; the section numbers in this list refer to the DHCPv6 DHCP service; the section numbers in this list refer to the DHCPv6
specification: specification:
Option Request: specifies the configuration information that the Option Request: specifies the configuration information that the
client is requesting from the server (section 22.7) client is requesting from the server (section 22.7)
Status Code: used to indicate completion status or other status Status Code: used to indicate completion status or other status
information (section 22.13) information (section 22.13)
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Servers and relay agents implement the following options for Servers and relay agents implement the following options for
stateless DHCP service; the section numbers in this list refer to the stateless DHCP service; the section numbers in this list refer to the
DHCPv6 specification: DHCPv6 specification:
Client message: Sent by a DHCP relay agent in a Relay-forward message Client message: Sent by a DHCP relay agent in a Relay-forward message
to carry the client message to a server (section 20) to carry the client message to a server (section 20)
Server message: Sent by a DHCP server in a Relay-reply message to Server message: Sent by a DHCP server in a Relay-reply message to
carry a response message to the relay agent (section 20) carry a response message to the relay agent (section 20)
Interface-ID: Sent by the DHCP relay agent and returned by the Interface-ID: Sent by the DHCP relay agent and returned by the
server to identify the interface to use to forward a message to server to identify the interface to use to forward a message to
the client (section 22.18) the client (section 22.18)
5.3 Options used for configuration information 5.3 Options Used for Configuration Information
Clients and servers use the following options to pass configuration Clients and servers use the following options to pass configuration
information to clients; note that other options for configuration information to clients; note that other options for configuration
information may be specified in future Internet Standards: information may be specified in future Internet Standards:
DNS Recursive Name Servers: specifies the DNS recursive name servers DNS Recursive Name Servers: specifies the DNS recursive name servers
[7] the client uses for name resolution; see "DNS Configuration [7] the client uses for name resolution; see "DNS Configuration
options for DHCPv6" [3] options for DHCPv6" [3]
DNS search list: specifies the domain names to be searched DNS search list: specifies the domain names to be searched
during name resolution; see "DNS Configuration options for DHCPv6" during name resolution; see "DNS Configuration options for DHCPv6"
[3] [3]
SIP Servers: specifies the SIP servers the client uses SIP Servers: specifies the SIP servers the client uses
to obtain a list of domain names of IPv6 addresses that can be to obtain a list of domain names of IPv6 addresses that can be
mapped to one or more SIP outbound proxy servers [4] mapped to one or more SIP outbound proxy servers [5]
5.4 Other options used in stateless DHCP 5.4 Other Options Used in Stateless DHCP
Clients and servers may implement the following options for stateless Clients and servers may implement the following options for stateless
DHCP service; the section numbers in this list refer to the DHCPv6 DHCP service; the section numbers in this list refer to the DHCPv6
specification, RFC 3315>: specification:
Preference: Sent by a DHCP server to indicate the preference Preference: Sent by a DHCP server to indicate the preference
level for the server (section 22.8) level for the server (section 22.8)
Elapsed time: Sent by a DHCP client to indicate the time since the Elapsed time: Sent by a DHCP client to indicate the time since the
client began the DHCP configuration process (section 22.9) client began the DHCP configuration process (section 22.9)
User Class: Sent by a DHCP client to give additional information User Class: Sent by a DHCP client to give additional information
to the server for selecting configuration parameters for the to the server for selecting configuration parameters for the
client (section 22.15) client (section 22.15)
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service may be used to mount spoofing, man-in-the-middle, service may be used to mount spoofing, man-in-the-middle,
denial-of-service and other attacks. These attacks are described in denial-of-service and other attacks. These attacks are described in
more detail in the specifications for each of the options that carry more detail in the specifications for each of the options that carry
configuration information. Authenticated DHCPv6, as described in configuration information. Authenticated DHCPv6, as described in
sections 21 and 22.11 of the DHCPv6 specification, can be used to sections 21 and 22.11 of the DHCPv6 specification, can be used to
avoid attacks mounted through the stateless DHCPv6 service. avoid attacks mounted through the stateless DHCPv6 service.
8. Acknowledgments 8. Acknowledgments
Jim Bound, Ted Lemon and Bernie Volz reviewed this document and Jim Bound, Ted Lemon and Bernie Volz reviewed this document and
contributed editorial suggestions. Thanks to Peter Barany, Christian contributed editorial suggestions. Thanks to Peter Barany, Tim
Huitema and Pekka Savola for their review and comments. Chown, Christian Huitema, Tatuya Jinmei, Ted Lemon, Pekka Savola and
Juha Wiljakka for their review and comments.
Normative References Normative References
[1] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. [1] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 3315, July 2003. RFC 3315, July 2003.
[2] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) [2] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC 2460, December 1998. Specification", RFC 2460, December 1998.
Informative References
[3] Droms, R., "DNS Configuration Options for DHCPv6", [3] Droms, R., "DNS Configuration Options for DHCPv6",
draft-ietf-dhc-dhcpv6-opt-dnsconfig-04 (work in progress), draft-ietf-dhc-dhcpv6-opt-dnsconfig-04 (work in progress),
August 2003. August 2003.
[4] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration [4] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for
IP Version 6 (IPv6)", RFC 2461, December 1998.
[5] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
Protocol (DHCPv6) Options for Session Initiation Protocol (SIP) Protocol (DHCPv6) Options for Session Initiation Protocol (SIP)
Servers", RFC 3319, July 2003. Servers", RFC 3319, July 2003.
Informative References
[5] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for
IP Version 6 (IPv6)", RFC 2461, December 1998.
[6] Thomson, S. and T. Narten, "IPv6 Stateless Address [6] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998. Autoconfiguration", RFC 2462, December 1998.
[7] Mockapetris, P., "Domain names - concepts and facilities", STD [7] Mockapetris, P., "Domain names - concepts and facilities", STD
13, RFC 1034, November 1987. 13, RFC 1034, November 1987.
Author's Address Author's Address
Ralph Droms Ralph Droms
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