BGP Custom Decision Process
draft-ietf-idr-custom-decision-05

 
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Inter-Domain Routing                                           A. Retana
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                                R. White
Expires: April 25, 2015                                         Ericsson
                                                        October 22, 2014

                      BGP Custom Decision Process
                   draft-ietf-idr-custom-decision-05

Abstract

   The BGP specification defines a Decision Process for installation of
   routes into the Loc-RIB.  This process takes into account an
   extensive series of path attributes, which can be manipulated to
   indicate preference for specific paths.  It is cumbersome (if at all
   possible) for the end user to define policies that will select, after
   partial comparison, a path based on subjective local (domain and/or
   node) criteria.

   This document defines a new Extended Community, called the Cost
   Community, which may be used in tie breaking during the best path
   selection process.  The end result is a local custom decision
   process.

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
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   This Internet-Draft will expire on April 25, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Retana & White           Expires April 25, 2015                 [Page 1]
Internet-Draft         BGP Custom Decision Process          October 2014

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  The BGP Cost Community  . . . . . . . . . . . . . . . . . . .   3
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Deployment Considerations . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Cost Community Point of Insertion Registry . . . . .   7
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .   8
     B.1.  Changes between the -00 and -01 versions. . . . . . . . .   8
     B.2.  Changes between the -01 and -02 versions. . . . . . . . .   8
     B.3.  Changes between the -02 and -03 versions. . . . . . . . .   8
     B.4.  Changes between the -03 and -04 versions. . . . . . . . .   8
     B.5.  Changes between the -04 and -05 versions. . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   There are a number of metrics available within the BGP decision
   process [RFC4271] which can be used to determine the exit point for
   traffic, but there is no metric, or combination of metrics, which can
   be used to break a tie among generally equal paths.

   o  LOCAL_PREF: The LOCAL_PREF is an absolute tie breaker near the
      beginning of the decision process.  There is no way to configure
      the LOCAL_PREF such that the MED, IGP metric, and other metrics
      are considered before breaking a tie.

   o  MED: The MULTI_EXIT_DISC is an indicator of which local entrance
      point an AS would like a peering AS to use; MED isn't suitable to
      break the tie between two equal cost paths learned from two peer
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