The Accumulated IGP Metric Attribute for BGP
draft-ietf-idr-aigp-08

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Last updated 2012-06-04
Replaces draft-rosen-idr-aigp
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Network Working Group                                  Pradosh Mohapatra
Internet Draft                                              Rex Fernando
Intended Status: Proposed Standard                         Eric C. Rosen
Expires: December 4, 2012                            Cisco Systems, Inc.

                                                            James Uttaro
                                                                     ATT

                                                            June 4, 2012

              The Accumulated IGP Metric Attribute for BGP

                       draft-ietf-idr-aigp-08.txt

Abstract

   Routing protocols that have been designed to run within a single
   administrative domain ("IGPs") generally do so by assigning a metric
   to each link, and then choosing as the installed path between two
   nodes the path for which the total distance (sum of the metric of
   each link along the path) is minimized.  BGP, designed to provide
   routing over a large number of independent administrative domains
   ("autonomous systems"), does not make its path selection decisions
   through the use of a metric.  It is generally recognized that any
   attempt to do so would incur significant scalability problems, as
   well as inter-administration coordination problems.  However, there
   are deployments in which a single administration runs several
   contiguous BGP networks.  In such cases, it can be desirable, within
   that single administrative domain, for BGP to select paths based on a
   metric, just as an IGP would do.  The purpose of this document is to
   provide a specification for doing so.

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Mohapatra, et al.                                               [Page 1]



Internet Draft         draft-ietf-idr-aigp-08.txt              June 2012

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Mohapatra, et al.                                               [Page 2]



Internet Draft         draft-ietf-idr-aigp-08.txt              June 2012

Table of Contents

 1          Specification of requirements  .........................   3
 2          Introduction  ..........................................   3
 3          AIGP Attribute  ........................................   5
 3.1        Applicability Restrictions and Cautions  ...............   6
 3.2        Restrictions on Sending/Receiving  .....................   6
 3.3        Creating and Modifying the AIGP Attribute  .............   7
 3.3.1      Originating the AIGP Attribute  ........................   7
 3.3.2      Modifications by the Originator  .......................   8
 3.3.3      Modifications by a Non-Originator  .....................   8
 4          Decision Process  ......................................  10
 4.1        When a Route has an AIGP Attribute  ....................  10
 4.2        When the Route to the Next Hop has an AIGP attribute  ..  11
 5          Deployment Considerations  .............................  12
 6          IANA Considerations  ...................................  12
 7          Security Considerations  ...............................  12
 8          Acknowledgments  .......................................  12
 9          Authors' Addresses  ....................................  13
10          Normative References  ..................................  13
11          Informative References  ................................  14
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