draft-ietf-dhc-dhcpv6-opt-prefix-delegation-01.txt   draft-ietf-dhc-dhcpv6-opt-prefix-delegation-02.txt 
DHC Working Group O. Troan DHC Working Group O. Troan
Internet-Draft R. Droms Internet-Draft R. Droms
Expires: May 28, 2003 Cisco Systems Expires: August 11, 2003 Cisco Systems
November 27, 2002 February 10, 2003
IPv6 Prefix Options for DHCPv6 IPv6 Prefix Options for DHCPv6
draft-ietf-dhc-dhcpv6-opt-prefix-delegation-01.txt draft-ietf-dhc-dhcpv6-opt-prefix-delegation-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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This Internet-Draft will expire on May 28, 2003. This Internet-Draft will expire on August 11, 2003.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract Abstract
The Prefix Delegation options provide a mechanism for automated The Prefix Delegation options provide a mechanism for automated
delegation of IPv6 prefixes using DHCP. This mechanism is intended delegation of IPv6 prefixes using DHCP. This mechanism is intended
for delegating long-lived prefix from a delegating router to a for delegating long-lived prefix from a delegating router to a
requesting router, across an administrative boundary, where the requesting router, across an administrative boundary, where the
delegating router does not require knowledge about the topology of delegating router does not require knowledge about the topology of
the links in the network to which the prefixes will be assigned. the links in the network to which the prefixes will be assigned.
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2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Model and Applicability . . . . . . . . . . . . . . . . . . 4 4. Model and Applicability . . . . . . . . . . . . . . . . . . 4
5. Identity Association for Prefix Delegation . . . . . . . . . 6 5. Identity Association for Prefix Delegation . . . . . . . . . 6
6. Overview of DHCP with Prefix Delegation . . . . . . . . . . 7 6. Overview of DHCP with Prefix Delegation . . . . . . . . . . 7
7. Interface Selection . . . . . . . . . . . . . . . . . . . . 7 7. Interface Selection . . . . . . . . . . . . . . . . . . . . 7
8. Identity Association for Prefix Delegation Option . . . . . 8 8. Identity Association for Prefix Delegation Option . . . . . 8
9. IA_PD Prefix option . . . . . . . . . . . . . . . . . . . . 9 9. IA_PD Prefix option . . . . . . . . . . . . . . . . . . . . 9
10. Delegating Router Solicitation . . . . . . . . . . . . . . . 11 10. Delegating Router Solicitation . . . . . . . . . . . . . . . 11
10.1 Requesting router behaviour . . . . . . . . . . . . . . . . 11 10.1 Requesting router behaviour . . . . . . . . . . . . . . . . 11
10.2 Delegating router behaviour . . . . . . . . . . . . . . . . 12 10.2 Delegating router behaviour . . . . . . . . . . . . . . . . 11
11. Requesting router initiated prefix delegation . . . . . . . 12 11. Requesting router initiated prefix delegation . . . . . . . 12
11.1 Requesting router behaviour . . . . . . . . . . . . . . . . 12 11.1 Requesting router behaviour . . . . . . . . . . . . . . . . 13
11.2 Delegating Router behaviour . . . . . . . . . . . . . . . . 14 11.2 Delegating Router behaviour . . . . . . . . . . . . . . . . 14
12. Prefix Delegation reconfiguration . . . . . . . . . . . . . 15 12. Prefix Delegation reconfiguration . . . . . . . . . . . . . 15
12.1 Delegating Router behaviour . . . . . . . . . . . . . . . . 15 12.1 Delegating Router behaviour . . . . . . . . . . . . . . . . 15
12.2 Requesting Router behaviour . . . . . . . . . . . . . . . . 15 12.2 Requesting Router behaviour . . . . . . . . . . . . . . . . 15
13. Relay agent behaviour . . . . . . . . . . . . . . . . . . . 15 13. Relay agent behaviour . . . . . . . . . . . . . . . . . . . 15
14. Security Considerations . . . . . . . . . . . . . . . . . . 15 14. Security Considerations . . . . . . . . . . . . . . . . . . 15
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . 16
16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 16. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
17. Changes since revision-01 . . . . . . . . . . . . . . . . . 16
Normative References . . . . . . . . . . . . . . . . . . . . 16 Normative References . . . . . . . . . . . . . . . . . . . . 16
Informative References . . . . . . . . . . . . . . . . . . . 17 Informative References . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17
Full Copyright Statement . . . . . . . . . . . . . . . . . . 18 Full Copyright Statement . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
This document describes new options for DHCP, which provide a This document describes new options for DHCP, which provide a
mechanism for the delegation of IPv6 prefixes. Through these mechanism for the delegation of IPv6 prefixes. Through these
options, a delegating router can delegate prefixes to authorised options, a delegating router can delegate prefixes to authorised
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In a message sent by a requesting router to a delegating router, the In a message sent by a requesting router to a delegating router, the
values in the fields can be used to indicate the requesting router's values in the fields can be used to indicate the requesting router's
preference for those values. The requesting router may send a value preference for those values. The requesting router may send a value
of zero to indicate no preference. A requesting router may set the of zero to indicate no preference. A requesting router may set the
IPv6 prefix field to zero and a given value in the prefix-length IPv6 prefix field to zero and a given value in the prefix-length
field to indicate a preference for the size of the prefix to be field to indicate a preference for the size of the prefix to be
delegated. delegated.
In a message sent by a delegating router the preferred and valid In a message sent by a delegating router the preferred and valid
lifetimes should be set to the values specified in section "Router lifetimes should be set to the values of AdvPreferredLifetime and
Configuration Variables" of RFC2461 [3], unless administratively AdvValidLifetime as specified in section "Router Configuration
configured. Variables" of RFC2461 [3], unless administratively configured.
In a message sent by a delegating router to a requesting router, the The values in the preferred and valid lifetimes are the number of
requesting router MUST use the value in the valid lifetime field and seconds remaining for each lifetime.
MAY use the value in the preferred lifetime field. The values in the
preferred and valid lifetimes are the number of seconds remaining for
each lifetime.
An IA_PD Prefix option may appear only in an IA_PD option. More than An IA_PD Prefix option may appear only in an IA_PD option. More than
one IA_PD Prefix Option can appear in a single IA_PD option. one IA_PD Prefix Option can appear in a single IA_PD option.
The status of any operations involving this IA_PD Prefix option is The status of any operations involving this IA_PD Prefix option is
indicated in a Status Code option in the IAprefix-options field. indicated in a Status Code option in the IAprefix-options field.
10. Delegating Router Solicitation 10. Delegating Router Solicitation
The requesting router locates and selects a delegating router in the The requesting router locates and selects a delegating router in the
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prefix(es) to the requesting router, the delegating router selects prefix(es) to the requesting router, the delegating router selects
the prefix(es) to be delegated to the requesting router. The the prefix(es) to be delegated to the requesting router. The
mechanism through which the delegating router selects prefix(es) for mechanism through which the delegating router selects prefix(es) for
delegation is not specified in this document. Examples of ways in delegation is not specified in this document. Examples of ways in
which the delegating router might select prefix(es) for a requesting which the delegating router might select prefix(es) for a requesting
router include: static assignment based on subscription to an ISP; router include: static assignment based on subscription to an ISP;
dynamic assignment from a pool of available prefixes; selection based dynamic assignment from a pool of available prefixes; selection based
on an external authority such as a RADIUS server using the Framed- on an external authority such as a RADIUS server using the Framed-
IPv6-Prefix option as described in RFC 3162 [7]. IPv6-Prefix option as described in RFC 3162 [7].
If the delegating router cannot delegate any prefixes to an IA_PD in
the message from the requesting router, the delegating router MUST
include the IA_PD in the Reply message with no prefixes in the IA_PD
and a Status Code option in the IA_PD containing status code
NoPrefixAvail.
If the requesting router includes an IA_PD Prefix option in the IA_PD If the requesting router includes an IA_PD Prefix option in the IA_PD
option in its Solicit message, the delegating router MAY choose to option in its Solicit message, the delegating router MAY choose to
use the information in that option to select the prefix(es) or prefix use the information in that option to select the prefix(es) or prefix
size to be delegated to the requesting router. size to be delegated to the requesting router.
The delegating router sends an Advertise message to the requesting The delegating router sends an Advertise message to the requesting
router in the same way as described in section "Creation and router in the same way as described in section "Creation and
transmission of Advertise messages" in the DHCP specification [6]. transmission of Advertise messages" in the DHCP specification [6].
The delegating router MUST include an IA_PD option, identifying any The delegating router MUST include an IA_PD option, identifying any
prefix(es) that the delegating router will delegate to the requesting prefix(es) that the delegating router will delegate to the requesting
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ask for such verification include: ask for such verification include:
o The requesting router reboots. o The requesting router reboots.
o The requesting router's upstream link flaps. o The requesting router's upstream link flaps.
o The requesting router is physically disconnected from a wired o The requesting router is physically disconnected from a wired
connection. connection.
If such verification is needed the requesting router MUST initiate a If such verification is needed the requesting router MUST initiate a
Renew/Reply message exchange as described in the section "Creation Rebind/Reply message exchange as described in the section "Creation
and Transmission of Renew Messages" of the DHCP specification [6]. and Transmission of Rebind Messages" of the DHCP specification [6],
The requesting router includes any IA_PDs, along with prefixes with the exception that the retransmission parameters should be set
associated with those IA_PDs in its Renew message. as for the Confirm message, described in the section "Creation and
Transmission of Confirm Messages" of the DHCP specification [6]. The
requesting router includes any IA_PDs, along with prefixes associated
with those IA_PDs in its Rebind message.
Each prefix has valid and preferred lifetimes whose duration is Each prefix has valid and preferred lifetimes whose duration is
specified in the IA_PD Prefix option for that prefix. The requesting specified in the IA_PD Prefix option for that prefix. The requesting
router uses Renew and Rebind messages to request the extension of the router uses Renew and Rebind messages to request the extension of the
lifetimes of a delegated prefix. lifetimes of a delegated prefix.
The requesting router uses a Release message to return a delegated The requesting router uses a Release message to return a delegated
prefix to a delegating router. The prefixes to be released MUST be prefix to a delegating router. The prefixes to be released MUST be
included in the IA_PDs. included in the IA_PDs.
The Confirm and Decline message types are not used with Prefix The Confirm and Decline message types are not used with Prefix
Delegation. Delegation.
Upon the receipt of a valid Reply message, the requesting router Upon the receipt of a valid Reply message, for each IA_PD the
assigns a subnet from each of the delegated prefixes to each of the requesting router assigns a subnet from each of the delegated
links to which it is attached, with the following exception: the prefixes to each of the links to which the associated interfaces are
requesting router MUST NOT assign any delegated prefixes or subnets attached, with the following exception: the requesting router MUST
from the delegated prefix(es) to the link through which it received NOT assign any delegated prefixes or subnets from the delegated
the DHCP message from the delegating router. prefix(es) to the link through which it received the DHCP message
from the delegating router.
When a requesting router subnets a delegated prefix, it must assign When a requesting router subnets a delegated prefix, it must assign
additional bits to the prefix to generate unique, longer prefixes. additional bits to the prefix to generate unique, longer prefixes.
For example, if the requesting router in Figure 1 were delegated For example, if the requesting router in Figure 1 were delegated
3FFE:FFFF:0::/48, it might generate 3FFE:FFFF:0:1::/64 and 3FFE:FFFF:0::/48, it might generate 3FFE:FFFF:0:1::/64 and
3FFE:FFFF:0:2::/64 for assignment to the two links in the subscriber 3FFE:FFFF:0:2::/64 for assignment to the two links in the subscriber
network. If the requesting router were delegated 3FFE:FFFF:0::/48 network. If the requesting router were delegated 3FFE:FFFF:0::/48
and 3FFE:FFFF:1::/48, it might assign 3FFE:FFFF:0:1::/64 and and 3FFE:FFFF:1::/48, it might assign 3FFE:FFFF:0:1::/64 and
3FFE:FFFF:1:1::/64 to one of the links, and 3FFE:FFFF:0:2::/64 and 3FFE:FFFF:1:1::/64 to one of the links, and 3FFE:FFFF:0:2::/64 and
3FFE:FFFF:1:2::/64 for assignment to the other link. 3FFE:FFFF:1:2::/64 for assignment to the other link.
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IANA is requested to assign a status code to the NoPrefixAvail status IANA is requested to assign a status code to the NoPrefixAvail status
code from the status-code space as defined in section "Status Codes" code from the status-code space as defined in section "Status Codes"
of the DHCPv6 specification [6]. of the DHCPv6 specification [6].
16. Acknowledgements 16. Acknowledgements
Thanks for the input and review by (in alphabetical order) Steve Thanks for the input and review by (in alphabetical order) Steve
Deering, Dave Forster, Brian Haberman, Tatuya Jinmei, Shin Miyakawa, Deering, Dave Forster, Brian Haberman, Tatuya Jinmei, Shin Miyakawa,
Pekka Savola, Bernie Volz, Trevor Warwick and Toshi Yamasaki. Pekka Savola, Bernie Volz, Trevor Warwick and Toshi Yamasaki.
17. Changes since revision-01
o Clarified the usage of how Preferred/Valid lifetimes should be
used in Router Advertisements.
o Clarified the use of NoPrefixAvail in the case were the delegating
router cannot delegate any prefixes.
o Use Rebind/Reply message exchange for binding confirmation rather
than Renew/Reply.
Normative References Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[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.
[3] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for [3] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery for
IP Version 6 (IPv6)", RFC 2461, December 1998. IP Version 6 (IPv6)", RFC 2461, December 1998.
[4] Hinden, R. and S. Deering, "IP Version 6 Addressing [4] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998. Architecture", RFC 2373, July 1998.
[5] Thomson, S. and T. Narten, "IPv6 Stateless Address [5] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998. Autoconfiguration", RFC 2462, December 1998.
[6] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R. [6] Droms, R., "Dynamic Host Configuration Protocol for IPv6
Droms (ed.), "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", draft-ietf-dhc-dhcpv6-28 (work in progress), November
(DHCPv6)", draft-ietf-dhc-dhcpv6-27 (work in progress), 2002.
September 2002.
[7] Aboba, B., Zorn, G. and D. Mitton, "RADIUS and IPv6", RFC 3162, [7] Aboba, B., Zorn, G. and D. Mitton, "RADIUS and IPv6", RFC 3162,
August 2001. August 2001.
Informative References Informative References
[8] Miyakawa, S., "Requirements for IPv6 prefix delegation", draft- [8] Miyakawa, S., "Requirements for IPv6 prefix delegation", draft-
ietf-ipv6-prefix-delegation-requirement-00 (work in progress), ietf-ipv6-prefix-delegation-requirement-00 (work in progress),
November 2002. November 2002.
Authors' Addresses Authors' Addresses
Ole Troan Ole Troan
Cisco Systems Cisco Systems
4 The Square 250 Longwater Avenue
Stockley Park Reading RG2 6GB
Uxbridge UB11 1BL
United Kingdom United Kingdom
Phone: +44 20 8824 8666 Phone: +44 20 8824 8666
EMail: ot@cisco.com EMail: ot@cisco.com
Ralph Droms Ralph Droms
Cisco Systems Cisco Systems
300 Apollo Drive 300 Apollo Drive
Chelmsford, MA 01824 Chelmsford, MA 01824
USA USA
Phone: +1 978 497 4733 Phone: +1 978 497 4733
EMail: rdroms@cisco.com EMail: rdroms@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of
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