One document matched: draft-haas-idr-flowspec-redirect-rt-bis-00.txt

Internet Engineering Task Force                             J. Haas, Ed.
Internet-Draft                                          Juniper Networks
Updates: 5575 (if approved)                             November 5, 2013
Intended status: Standards Track
Expires: May 9, 2014


       Clarification of the Flowspec Redirect Extended Community
               draft-haas-idr-flowspec-redirect-rt-bis-00

Abstract

   This document clarifies the formatting of the the BGP Flowspec
   Redirect Extended Community, originally documented in RFC 5575.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on May 9, 2014.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5











































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1.  Introduction

   Dissemination of Flow Specification Rules [RFC5575], commonly known
   as BGP Flowspec, provided for a BGP Extended Community [RFC4360] that
   served to redirect traffic to a VRF routing instance that matched the
   flow specification NLRI.  In that RFC, the Redirect Extended
   Community was documented as follows:

   : +--------+--------------------+--------------------------+
   : | type   | extended community | encoding                 |
   : +--------+--------------------+--------------------------+
   : | 0x8008 | redirect           | 6-byte Route Target      |
   : +--------+--------------------+--------------------------+
   :
   : [...]
   :
   : Redirect:  The redirect extended community allows the traffic to be
   : redirected to a VRF routing instance that lists the specified
   : route-target in its import policy.  If several local instances
   : match this criteria, the choice between them is a local matter
   : (for example, the instance with the lowest Route Distinguisher
   : value can be elected).  This extended community uses the same
   : encoding as the Route Target extended community [RFC4360].
   : [...]
   :
   : 11. IANA Considerations
   : [...]
   :
   : The following traffic filtering flow specification rules have been
   : allocated by IANA from the "BGP Extended Communities Type -
   : Experimental Use" registry as follows:
   : [...]
   :
   : 0x8008 - Flow spec redirect

   The IANA registry of BGP Extended Communities clearly identifies
   communities of specific formats.  For example, "Two-octet AS Specific
   Extended Community" [RFC4360], "Four-octet AS Specific Extended
   Community" [RFC5668] and "IPv4 Address Specific Extended Community"
   [RFC4360].  Route Targets [RFC4360] identify this format in the high-
   order (Type) octet of the Extended Community and set the value of the
   low-order (Sub-Type) octet to 0x02.  The Value field of the Route
   Target Extended Community is intended to be interpreted in the
   context of its format.

   Since the Redirect Extended Community only registered a single code-
   point in the IANA BGP Extended Community registry, a common
   interpretation of the Redirect Extended Community's "6-byte Route



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   Target" has been to look for any matching Route Target sharing the
   same Value portion of its Extended Community.  Thus, multiple Route
   Targets provisioned in a router's VRFs might match even though the
   format was different.

   This "Value wildcard" behavior does not matched deployed
   implementations of BGP Flowspec.  Deployed implementations of BGP
   Flowspec use the following formatting for the Redirect Extended
   Community:

   +--------+--------------------+-------------------------------------+
   | type   | extended community | encoding                            |
   +--------+--------------------+-------------------------------------+
   | 0x8008 | redirect AS-2byte  | 2-octet AS, 4-octet Value           |
   | 0x8108 | redirect IPv4      | 4-octet IPv4 Address, 2-octet Value |
   | 0x8208 | redirect AS-4byte  | 4-octet AS, 2-octet Value           |
   +--------+--------------------+-------------------------------------+

   It should be noted that the low-order nybble of the Redirect's Type
   field corresponds to the Route Target Extended Community format field
   (Type).  (See [RFC4360], Secs. 3.1, 3.2 and [RFC5668], Sec. 2.)  The
   low order octet (Sub-Type) of the Redirect Extended Community remains
   0x08, contrasted to 0x02 for Route Targets.


2.  IANA Considerations

   IANA is requested to update the "BGP Extended Communities Type -
   Experimental Use" registry as follows:

               0x8008 - Flow spec redirect AS-2byte
               0x8108 - Flow spec redirect IPv4
               0x8208 - Flow spec redirect AS-4byte


3.  Security Considerations

   This document introduces no additional security considerations than
   those already covered in [RFC5575].


4.  Acknowledgements

   The contents of this document was raised as part of implementation
   discussions of BGP Flowspec with the following individuals:






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      Andrew Karch (Cisco)

      Robert Raszuk (NTT I3)

      Adam Simpson (Alcatel-Lucent)

      Matthieu Texier (Arbor Networks)

      Kaliraj Vairavakkalai (Juniper)


5.  Normative References

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, February 2006.

   [RFC5575]  Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, August 2009.

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


Author's Address

   Jeffrey Haas (editor)
   Juniper Networks
   1194 N. Mathida Ave.
   Sunnyvale, CA  94089
   US

   Email: jhaas@juniper.net


















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