G. Huston
APNIC
September 20, 2005


    BGP support for 4-Byte AS Numbers - Implementation Survey Report
                

Abstract

   This document provides a survey of BGP-4 4-Byte AS Number support
   implementations.


1.  Survey Summary

   This document provides a survey of BGP-4 4-Byte AS Number Support
   [ID.4ByteAS] implementations.  After a brief summary, each response
   is listed.  The editor, makes no claim as to the accuracy of the
   information provided.


2.  Summary Forms

2.1.  Juniper Networks

   Organization: Juniper Networks

   Person filling out this form:
      Bruno Rijsman <brijsman@juniper.net>

   Implementation:
      JUNOSe 4-1-0 and later

   Does the implementation include all parts of the specification:
      Yes

   Are there parts of the specification that are unclear where the
   implementor had to exercise some judgement that may impact
   interoperability?
      *  It isn't clear what to do if the information in the old as-path
         is inconsistent with the information in the new as-path.
      *  There some places where AS numbers are used where it wasn't
         clear how to deal with 4-octet as-numbers (e.g. extended
         communities).
      *  It isn't spelled out that this capability cannot be dynamically
         negotiated.

   Has there been any interoperability testing?
      Yes; no problems were discovered.

      1.  NEW / OLD ineroperability testing with:
             Juniper ERX (older version which does not support draft)
             Juniper M/T/J
             Cisco 7500

      2.  NEW / NEW interoperability testing with:
             Juniper M/T/J
             Redback SmartEdge

      3.  Most deployed Juniper ERX routers run code which supports
          4-octet AS-numbers (and the feature is enabled by default).
          This provides some confidence that the draft does not cause
          interoperability problems.  Note however that the NEW_AS_PATH
          attribute is not generated unless the AS-path contains at
          least one AS-number greater than 65535 which is -as far as we
          know- not yet the case in the Internet today.


   Has there been testing of the interface between this implementation
   and the 2-byte BGP implementation on the NEW (4-byte) to OLD (2byte)
   update path?
      Yes

   Has there been testing of the OLD (2-byte) to NEW (4-byte) path?
      Yes

   Have there been any issues noted with the mechanism to reconstruct
   the 4-byte AS path from the NEW_AS-PATH attribute and the 2-byte AS
   Path on an OLD -NEW BGP update session?
      It isn't clear what to do if the information in the old as-path is
      inconsistent with the information in the new as-path.

   Any other comments regarding the implementation
      Some older versions of Cisco IOS send an unsupported capability
      notification (instead of ignoring the capability) when they
      receive a capability advertisement which they don't recognize and
      which has non-empty data.  The 4-octet as-number capability is
      such a capability.  Our implementation recognizes this
      notification and stops automatically stops advertising the 4-octet
      as-numbers capability (and others) until the next hard clear on
      the BGP session.

2.2.  Redback

   Organization: Redback

   Person filling out this form:
      Albert Tian <tian@redback.com>

   Does the implementation include all parts of the specification:
      Yes

   Are there parts of the specification that are unclear where the
   implementor had to exercise some judgement that may impact
   interoperability?
      No.

   Has there been any interoperability testing?
      Yes

   Has there been testing of the interface between this implementation
   and the 2-byte BGP implementation on the NEW (4-byte) to OLD (2byte)
   update path?
      Yes (Cisco: 2-byte; Redback: 4 byte).

   Has there been testing of the OLD (2-byte) to NEW (4-byte) path?


      Yes. (Cisco: 2-byte; Redback: 4-byte).

   Have there been any issues noted with the mechanism to reconstruct
   the 4-byte AS path from the NEW_AS-PATH attribute and the 2-byte AS
   Path on an OLD -NEW BGP update session?
      No

   Have there been any issues noted with the mechanism to reconstruct
   the 4-byte AS path from the NEW_AS-PATH attribute and the 2-byte AS
   Path on an OLD -> NEW BGP update session?
      No.

   Any other comments regarding the implementation
      No


3.  IANA Considerations

   No IANA considerations are noted in this document


4.  Security Considerations

   Security considerations are documented in [ID.4ByteAS].

5.  References

   [ID.4ByteAS]
              Vohra, Q. and E. Chen, "BGP support for four-octet AS
              number space", Work in progress, Internet
              Draft: draft-ietf-idr-as4bytes-10.txt, July 2005.


Author's Address

   Geoff Huston
   Asia Pacific Network Information Centre

   Email: gih@apnic.net
   URI:   http://www.apnic.net