Network Working Group G. Michaelson Request for Comments: DRAFT APNIC Expires December 2006 Canonical representation of 4-byte AS numbers draft-michaelson-4byte-as-representation-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract A single representation for 4-byte AS numbers is proposed, to avoid any confusion in interpreting the two 2-byte quantities that make them. The syntax chosen avoids collision with BGP community string parsing of AS numbers. It is recommended that only this representation be used by all documents and systems referring to 4-byte AS numbers. Nomenclature 1.0 Proposed canonical 4-byte AS representation 4 Byte AS numbers are defined in . It is proposed to identify 4-byte AS Numbers using a syntax of <high order 16 bit value in decimal>.<low order 16 bit value in decimal>. Accordingly, a 4-byte AS Number of value 65546 (decimal) would be identified as "1.10". 2.0 Terminology "2-byte only AS Numbers" refers to AS Numbers in the range 0 - 65535 "4-byte only AS Numbers" refers to AS Numbers in the range 1.0 - 65535.65535 (decimal range 65,536 - 4,294,967,295) "4-byte AS Numbers" refers to AS Numbers in the range 0.0 - 65535.65535 (decimal range 0 - 4,294,967,295) 3.0 Discussion To avoid confusion, a single notation to represent 4-byte AS is required. Initially, the ":" was proposed to separate the 2-byte components. However this clashes with use of the ":" character in community attribute syntax. This notation has been informally adopted by at least one vendor, and used consistently in presentations in the RIR community towards the deployment of 4-byte AS. Therefore it seems sensible to formalize its use as the preferred representation of a 4-byte AS. 4.0 Author's Note: This proposal was motivated by a discussion with Geoff Huston. The text of the definition of a 4-byte AS is taken from . 5.0 Security Considerations Security considerations are not discussed in this memo. 6.0 Author's Address: George Michaelson APNIC Level 1, 33 Park Road, Milton, Q4064 Australia 7.0 References  http://www1.ietf.org/internet-drafts/draft-ietf-idr-as4bytes-12.txt  http://www.ripe.net/ripe/policies/proposals/2005-12.html 8.0 Comments & Feedback Comments are solicited and should be addressed to the working group's mailing list at firstname.lastname@example.org and/or the author. 9.0 Authors email address email@example.com 10.0 Copyright Declaration Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights." "This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.