INTERNET-DRAFT R. Hinden, Nokia February 4, 2003 S. Deering, Cisco IPv6 Global Unicast Address Format for the 2000::/3 Prefix 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- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This internet draft expires on August 4, 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. draft-ietf-ipv6-unicast-aggr-v2-01.txt [Page 1] INTERNET-DRAFT IPv6 Address Format for 2000::/3 Prefix February 2003 1.0 Introduction This document defines the unicast address format for the 2000::/3 (001 binary) prefix. The address format defined in this document is consistent with the IPv6 Protocol [IPV6] and the "IPv6 Addressing Architecture" [ARCH]. It is designed to facilitate scalable Internet routing. RFC2374, "An IPv6 Aggregatable Global Unicast Address Format" defined a structured allocation structure of global unicast IPv6 addresses with named fields (e.g., TLA, NLA, etc.). While this approach was originally thought to be a good way to allocate IPv6 addresses, subsequent experience and discussion showed that it would be better to leave flexibility in the definition of IPv6 allocation policies to the Internet Address Registries, in order to allow a better balance among the competing requirements. This is consistent with the recommendations made by the IAB and IESG in [RFC3177]. This document removes the defined structure and generalizes the fields in the global unicast address format. This documented replaces RFC2374, "An IPv6 Aggregatable Global Unicast Address Format". RFC 2374 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 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 draft-ietf-ipv6-unicast-aggr-v2-01.txt [Page 2] INTERNET-DRAFT IPv6 Address Format for 2000::/3 Prefix February 2003 and to be constructed in Modified EUI-64 format. The specific format of global unicast address under the 2000::/3 prefix is: | 3 | n bits | 61-n bits | 64 bits | +---+--------------------+-----------+----------------------------+ |001| 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 Acknowledgments The authors would like to express our thanks to Margaret Wasserman, Brian Carpenter, Pekka Savola, Alain Durand, Fred Templin, Michel Py, and Jun-ichiro itojun Hagino for their review and constructive comments. 4.0 References Normative [ARCH] Hinden, R., "IP Version 6 Addressing Architecture", Internet Draft, , 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. [RFC3177] IAB/IESG, "Recommendations on IPv6 Address Allocations to Sites" RFC3177, September 2001. 5.0 Security Considerations IPv6 addressing documents do not have any direct impact on Internet infrastructure security. draft-ietf-ipv6-unicast-aggr-v2-01.txt [Page 3] INTERNET-DRAFT IPv6 Address Format for 2000::/3 Prefix February 2003 6.0 Authors' Addresses Robert M. Hinden Nokia 313 Fairchild Drive Mountain View, CA US email: hinden@iprg.nokia.com Stephen E. Deering Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 US email: deering@cisco.com draft-ietf-ipv6-unicast-aggr-v2-01.txt [Page 4]