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Versions: (draft-wkumari-idr-as0) 00 01 02 03 04 05 06

idr                                                            W. Kumari
Internet-Draft                                                    Google
Intended status: Standards Track                                 R. Bush
Expires: July 13, 2012                         Internet Initiative Japan
                                                             H. Schiller
                                                                 Verizon
                                                                K. Patel
                                                           Cisco Systems
                                                        January 10, 2012


                    Codification of AS 0 processing.
                         draft-ietf-idr-as0-02

Abstract

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

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on July 13, 2012.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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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.  A BGP speaker SHOULD NOT generate or propagate an UPDATE
   with zero in any field where an AS number is expected (for example,
   "4-Octet AS specific Extended Community" [RFC5668]).

   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].

   As UPDATE with zero in any other field where an AS number is expected
   (for example, "4-Octet AS specific Extended Community" [RFC5668])
   SHOULD be treated as malformed and handled appropriately.

   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



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   number zero.


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,
   Keyur Patel, 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.




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

   [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.

   [RFC5668]  Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
              Specific BGP Extended Community", RFC 5668, October 2009.

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.



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   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

   o  Fixed the refernce 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.


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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