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Network Working Group G. Huston
Request for Comments: 5396 G. Michaelson
Category: Standards Track APNIC
December 2008
Textual Representation of Autonomous System (AS) Numbers
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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Abstract
A textual representation for Autonomous System (AS) numbers is
defined as the decimal value of the AS number. This textual
representation is to be used by all documents, systems, and user
interfaces referring to AS numbers.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Taxonomy of Representation Formats . . . . . . . . . . . . . . 2
3. Representation of AS Number Values . . . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 3
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 3
7. Informative References . . . . . . . . . . . . . . . . . . . . 3
Huston & Michaelson Standards Track [Page 1]
RFC 5396 ASN Notation December 2008 1. Introduction A textual representation for Autonomous System (AS) numbers is defined as the decimal value of the AS number. This textual representation is to be used by all documents, systems, and user interfaces referring to AS numbers. This document notes a number of potential representation formats and proposes the adoption of a decimal value notation for AS numbers, or "asplain" according to the representation taxonomy described here. 2. Taxonomy of Representation Formats A taxonomy of representation for AS numbers is as follows: asplain refers to a syntax scheme of representing all AS numbers using decimal integer notation. Using asplain notation, an AS number of value 65526 would be represented as the string "65526" and an AS number of value 65546 would be represented as the string "65546". asdot+ refers to a syntax scheme of representing all AS numbers using a notation of two integer values joined by a period character: <high order 16-bit value in decimal>.<low order 16-bit value in decimal>. Using asdot+ notation, an AS number of value 65526 would be represented as the string "0.65526" and an AS number of value 65546 would be represented as the string "1.10". asdot refers to a syntax scheme of representing AS number values less than 65536 using asplain notation and representing AS number values equal to or greater than 65536 using asdot+ notation. Using asdot notation, an AS number of value 65526 would be represented as the string "65526" and an AS number of value 65546 would be represented as the string "1.10". 3. Representation of AS Number Values To avoid confusion, a single textual notation is useful for documentation, configuration systems, reports, and external tools and information repositories. The decimal value representation, or "asplain" is proposed as the textual notation to use for AS numbers. The "asplain" representation represents the number as its decimal value, without any field delimiter, corresponding to the lack of any internal structure required by the use of AS numbers in the inter- domain routing context. Huston & Michaelson Standards Track [Page 2]
RFC 5396 ASN Notation December 2008 4. IANA Considerations IANA Registries should use decimal representation ("asplain") for AS numbers. 5. Security Considerations This document does not refer to matters associated with security of routing systems. 6. Acknowledgments The terminology of "asplain", "asdot", and "asdot+" was originally devised and described by Juergen Kammer in January 2007 [KAMMER2007]. 7. Informative References [KAMMER2007] Kammer, J., "AS Number Formats", Jan 2007, <http://quagga.ncc.eurodata.de/asnumformat.html>. Authors' Addresses Geoff Huston Asia Pacific Network Information Centre EMail: gih@apnic.net George Michaelson Asia Pacific Network Information Centre EMail: ggm@apnic.net Huston & Michaelson Standards Track [Page 3]