RFC 1930 (rfc1930) - Page 1 of 10

Guidelines for creation, selection, and registration of an Autonomous System (AS)

Network Working Group                                       J. Hawkinson
Request for Comments: 1930                                    BBN Planet
BCP: 6                                                          T. Bates
Category: Best Current Practice                                      MCI
                                                              March 1996


          Guidelines for creation, selection, and registration
                      of an Autonomous System (AS)

Status of this Memo

   This document specifies an Internet Best Current Practices for the
   Internet Community, and requests discussion and suggestions for
   improvements.  Distribution of this memo is unlimited.

Abstract

   This memo discusses when it is appropriate to register and utilize an
   Autonomous System (AS), and lists criteria for such.  ASes are the
   unit of routing policy in the modern world of exterior routing, and
   are specifically applicable to protocols like EGP (Exterior Gateway
   Protocol, now at historical status; see [EGP]), BGP (Border Gateway
   Protocol, the current de facto standard for inter-AS routing; see
   [BGP-4]), and IDRP (The OSI Inter-Domain Routing Protocol, which the
   Internet is expected to adopt when BGP becomes obsolete; see [IDRP]).
   It should be noted that the IDRP equivalent of an AS is the RDI, or
   Routing Domain Identifier.

Table of Contents

   1. Introduction ............................................    2
   2. Motivation ..............................................    2
   3. Definitions .............................................    2
   4. Common errors in allocating ASes ........................    5
   5. Criteria for the decision -- do I need an AS?  ..........    5
   5.1 Sample Cases ...........................................    6
   5.2 Other Factors ..........................................    7
   6. Speculation .............................................    7
   7. One prefix, one origin AS ...............................    8
   8. IGP issues ..............................................    8
   9. AS Space exhaustion .....................................    8
   10. Reserved AS Numbers ....................................    9
   11. Security Considerations ................................    9
   12. Acknowledgments ........................................    9
   13. References .............................................    9
   14. Authors' Addresses .....................................   10




Hawkinson & Bates        Best Current Practice