Codification of AS 0 processing.
draft-ietf-idr-as0-03

idr                                                            W. Kumari
Internet-Draft                                                    Google
Intended status: Standards Track                                 R. Bush
Expires: July 19, 2012                         Internet Initiative Japan
                                                             H. Schiller
                                                                 Verizon
                                                                K. Patel
                                                           Cisco Systems
                                                        January 16, 2012

                    Codification of AS 0 processing.
                         draft-ietf-idr-as0-03

Abstract

   This document proscribes the use of AS 0 in BGP OPEN and AS_PATH /
   AS4_PATH BGP attribute.

Status of this Memo

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   This Internet-Draft will expire on July 19, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . . . 3
   2.  Behavior  . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Changes / Author Notes.  . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Introduction

   Autonomous System 0 is listed in the IANA Autonomous System Number
   Registry as "Reserved - May be use to identify non-routed networks"
   ([IANA.AS_Numbers]).

   [I-D.ietf-sidr-iana-objects] specifies that AS number zero in a ROA
   is used to mark an NLRI which is to be marked as Invalid.

   No clear statement that AS 0 was proscribed could be found in any BGP
   specification.

   As at least two implementations discard routes containing AS 0 (and
   to allow approaches such as the above) this document codifies this
   behavior.

1.1.  Requirements notation

   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 [RFC2119].

2.  Behavior

   A BGP speaker MUST NOT originate or propagate a route with an AS
   number of zero in the AS_PATH, AS4_PATH, AGGREGATOR or AS4_AGGREGATOR
   attributes.

   An UPDATE message that contains the AS number of zero in the AS_PATH
   or AS4_PATH attribute MUST be considered as malformed, and be handled
   by the procedures specified in [I-D.ietf-idr-error-handling].

   An UPDATE message that contains the AS number of zero in the
   AGGREGATOR or AS4_AGGREGATOR attribute MUST be considered as
   malformed, and be handled by the procedures specified in
   [I-D.ietf-idr-rfc4893bis].

   If a BGP speaker receives zero as the peer AS in an OPEN message, it
   MUST abort the connection and send a NOTIFICATION with Error Code
   "OPEN Message Error" and subcode "Bad Peer AS" (see [RFC4271] Section
   6.2).  A router MUST NOT initiate a connection claiming to be AS
   number zero.

   Authors of future protocol extensions that carry the Autonomous
   System number are encouraged keep in mind that AS number zero is
   reserved and to provide clear direction on how to handle AS number
   zero.

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3.  IANA Considerations

   The IANA is requested to update the Reference for number 0 in the
   "Autonomous System (AS) Numbers" registry to reference this document.

4.  Security Considerations

   By allowing resource holders to say that AS 0 is the only valid
   origin for a route, we allow them to state that a particular address
   resource is not in use.  By ensuring that all implementations that
   see AS 0 in a route ignore that route, we prevent a malicious party
   from announcing routes containing AS 0 in an attempt to hijack those
   resources.

   In addition, by standardizing the behavior upon reception of an
   AS_PATH (or AS4_PATH) containing AS 0, this document makes the
   behavior better defined, and security gotchas often lurk in the
   undefined spaces.

5.  Acknowledgements

   The authors wish to thank Enke Chen, Brian Dickson, Bruno Decraene,
   Robert Raszuk, Jakob Heitz, Danny McPherson, Chris Morrow, iLya, John
   Scudder, Jeff Tantsura, Daniel Ginsburg and Susan Hares.  Apologies
   to those we may have missed, it was not intentional.

6.  References

6.1.  Normative References

   [I-D.ietf-idr-error-handling]
              Scudder, J., Chen, E., Mohapatra, P., and K. Patel,
              "Revised Error Handling for BGP UPDATE Messages",
              draft-ietf-idr-error-handling-00 (work in progress),
              November 2011.

   [I-D.ietf-idr-rfc4893bis]
              Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
              Number Space", draft-ietf-idr-rfc4893bis-04 (work in
              progress), July 2011.

   [IANA.AS_Numbers]
              IANA, "Autonomous System (AS) Numbers",
              <http://www.iana.org/assignments/as-numbers>.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

6.2.  Informative References

   [I-D.ietf-sidr-iana-objects]
              Manderson, T., Vegoda, L., and S. Kent, "RPKI Objects
              issued by IANA", draft-ietf-sidr-iana-objects-03 (work in
              progress), May 2011.

Appendix A.  Changes / Author Notes.

   [RFC Editor: Please remove this section before publication ]

   Draft accepted as IDR Doc, notes reset.  Please see notes for
   draft-wkumari-idr-as0.xml for prior comments.

   Changes -00.

   o  Added AS4_PATH -- Robert Raszuk.
   o  Change "bgp listener" to "bgp speaker" -- Enke Chen
   o  Consistent use of AS_PATH (v., AS-PATH and AS PATH) -- Danny
      McPherson
   o  New text for Sec 2 P1 -- Enke / Keyur / Scudder,
      http://www.ietf.org/mail-archive/web/idr/current/msg05786.html
   o  I made a boo boo -- I had the file open in 2 editors, made changes
      in one and overwrote them by saving on the other, then checked the
      broken one into SVN.  Apologies to all whose comments I may have
      missed...

   Changes -01

   o  The WG thread
      http://www.ietf.org/mail-archive/web/idr/current/msg05685.html
      showed a very strong preference for separating the error
      definition and handling -- the chairs also showed a prefernce to
      Publish this and point to the error handling that Enke will write.
   o  The originally suggested text ("An UPDATE message that contains
      the AS number of zero in the AS-PATH attribute MUST be...") only
      referenced the AS-PATH, readded AS4_PATH, *AGGREGATOR as suggested
      by Robert Raszak and Danny.

   Changes -02

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   o  Fixed the reference for *AGGREGATOR.  This required breaking it
      out into two sentences / clauses.
   o  Added text on other places where an AS can show up (e.g: "4-Octet
      AS specific Extended Community" [RFC5668]) -- thanks to Keyur.

   Changes - 03
   o  Removed text on other places where an AS can show up (e.g:
      "4-Octet AS specific Extended Community" [RFC5668]).
   o  Added *very* generic "Authors of future protocol extensions..."
      text

Authors' Addresses

   Warren Kumari
   Google
   1600 Amphitheatre Parkway
   Mountain View, CA  94043
   US

   Email: warren@kumari.net

   Randy Bush
   Internet Initiative Japan
   5147 Crystal Springs
   Bainbridge Island, WA  98110
   US

   Email: randy@psg.com

   Heather Schiller
   Verizon
   22001 Loudoun County Parkway
   Ashburn  20147
   US

   Email: heather.schiller@verizon.com

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   Keyur Patel
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Phone:
   Fax:
   Email: keyupate@cisco.com
   URI:

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