wdiff draft-ietf-ipv6-unicast-aggr-v2-01.txt draft-ietf-ipv6-unicast-aggr-v2-02.txt

INTERNET-DRAFT R. Hinden, Nokia
February 4, 26, 2003 S. Deering, Cisco
E. Nordmark, Sun

IPv6 Global Unicast Address Format for the 2000::/3 Prefix

<draft-ietf-ipv6-unicast-aggr-v2-01.txt>

<draft-ietf-ipv6-unicast-aggr-v2-02.txt>

Status of this Memo

This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
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The list of current Internet-Drafts can be accessed at
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This internet draft expires on August 4, 26, 2003.

Abstract

This document defines the unicast address format for the 2000::/3
(001 binary) prefix. The address format defined in this document is
consistent with RFC2460 "Internet Protocol, Version 6 (IPv6)
Specification" and RFCXXXX "IP Version 6 Addressing Architecture".

This documented replaces

RFC2374 "An IPv6 Aggregatable Global Unicast Address Format". RFC2374 will become historic.

1.0 Introduction

This document defines the unicast address format for the 2000::/3
(001 binary) prefix. The address format Format" defined in this document is
consistent with the
an IPv6 Protocol [IPV6] address allocation structure that includes TLA (Top Level
Aggregator) and NLA (Next Level Aggregator). This document replaces
RFC2374, and makes RFC 2374 and the "IPv6 Addressing
Architecture" [ARCH]. It is designed to facilitate scalable Internet
routing.

RFC2374, TLA/NLA structure historic.

1.0 Introduction

RFC2374 "An IPv6 Aggregatable Global Unicast Address Format" defined
an IPv6 address allocation structure that includes TLA (Top Level
Aggregator) and NLA (Next Level Aggregator). This document replaces
RFC2374, and makes RFC 2374 and the TLA/NLA structure historic.

2.0 TLA/NLA Made Historic

The TLA/NLA scheme has been replaced by a structured coordinated allocation
policy defined by the Regional Internet Registries (RIRs) [IPV6RIR].

Part of the motivation for obsoleting the TLA/NLA structure is
technical; for instance, there is concern that TLA/NLA is not the
technically best approach at this stage of the deployment of IPv6.
Moreover, the allocation of global unicast IPv6 addresses
with named fields (e.g., TLA, NLA, etc.).

While this approach was originally thought to be a good way is related to
allocate IPv6 addresses, subsequent experience policy and discussion showed
that it would be better
to leave flexibility in the definition stewardship of the IP address space and routing table size,
which the RIRs have been managing for IPv4. It is likely that the
RIRs' policy will evolve as IPv6 allocation policies deployment proceeds.

The IETF has provided technical input to the Internet Address Registries, in order
to allow a better balance among RIRs (for example,
[RFC3177]), which the competing requirements. This is
consistent with RIRs have taken into account when defining
their address allocation policy.

RFC2374 was the recommendations definition of addresses for Format Prefix 001
(2000::/3) which is formally made historic by this document. Even
though currently only 2000::/3 is being delegated by the IAB and IESG in
[RFC3177].

This document removes IANA,
implementations should not make any assumptions about 2000::/3 being
special, since the IANA might later be directed to delegate currently
unassigned parts of the defined structure and generalizes IPv6 address space to the
fields purpose of Global
Unicast as well.

The SLA (subnet local aggregator) field in the global unicast address format. RFC2374 remains in
function but with a different name in [ARCH]. Its new name is
"subnet ID".

This documented replaces RFC2374, "An IPv6 Aggregatable Global
Unicast Address Format". RFC 2374 RFC2374 will become historic.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].

2.0

3.0 Address Format

The general format for IPv6 global unicast addresses as defined in
"IP Version 6 Addressing Architecture" [ARCH] is as follows:

| n bits | m bits | 128-n-m bits |
+------------------------+-----------+----------------------------+
+-------------------------+-----------+----------------------------+
| global routing prefix | subnet ID | interface ID |
+------------------------+-----------+----------------------------+
+-------------------------+-----------+----------------------------+

where the global routing prefix is a (typically hierarchically-
structured) value assigned to a site (a cluster of subnets/links),
the subnet ID is an identifier of a subnet within the site, and the
interface ID is as defined in section 2.5.1 of [ARCH].

[ARCH] also requires that all unicast addresses, except those that
start with binary value 000, have Interface IDs that are 64 bits long
and to be constructed in Modified EUI-64 format. The specific format of
global unicast address under the 2000::/3
prefix in this case is:

| 3 | n bits | 61-n 64-n bits | 64 bits |
+---+--------------------+-----------+----------------------------+
|001|
+-------------------------+-----------+----------------------------+
| global routing prefix | subnet ID | interface ID |
+---+--------------------+-----------+----------------------------+
+-------------------------+-----------+----------------------------+

where the routing prefix is a value assigned to a identify a site (a
cluster of subnets/links), the subnet ID is an identifier of a subnet
within the site, and the interface ID is in modified EUI-64 format as
defined in [ARCH].

3.0

An example of the resulting format of global unicast address under
the 2000::/3 prefix that is currently being delegated by the IANA and
consistent with the recommendations in RFC3177 is:

4.0 Acknowledgments

The authors would like to express our thanks to Margaret Wasserman,
Brian Carpenter, Pekka Savola, Alain Durand, Brian
Carpenter, Fred Templin, Julian Sellers, Jun-ichiro itojun Hagino,
Margaret Wasserman, Michel Py, Pekka Savola, Tatuya Jinmei, and Jun-ichiro itojun Hagino
Thomas Narten for their review and constructive comments.

4.0

5.0 References

Normative

[ARCH] Hinden, R., "IP Version 6 Addressing Architecture",
Internet Draft, <draft-ietf-ipngwg-addr-arch-v3-11.txt>,
October 2002.

[IPV6] Deering, S., R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC2460, December 1998.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC2119, BCP14, March 1997.

Non-Normative

[IPV6RIR] APNIC, ARIN, RIPE NCC, "IPv6 Address Allocation and
Assignment Policy", Document ID: ripe-267,
http://www.ripe.net/ripe/docs/ipv6policy.html, January 22,
2003.

[RFC3177] IAB/IESG, "Recommendations on IPv6 Address Allocations to
Sites" RFC3177, September 2001.

5.0

6.0 Security Considerations

IPv6 addressing documents do not have any direct impact on Internet
infrastructure security.

6.0

7.0 Authors' Addresses

Robert M. Hinden email: bob.hinden@nokia.com
Nokia
313 Fairchild Drive
Mountain View, CA
US

email: hinden@iprg.nokia.com
Stephen E. Deering email: deering@cisco.com
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
US

Erik Nordmark email: deering@cisco.com erik.nordmark@sun.com
Sun Microsystems Laboratories
180, avenue de l'Europe
38334 SAINT ISMIER Cedex
France