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BGP Custom Decision Process
draft-ietf-idr-custom-decision-04

Document type: Active Internet-Draft (idr WG)
Document stream: IETF
Last updated: 2013-11-18
Intended RFC status: Unknown
Other versions: plain text, pdf, html

IETF State: WG Document
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: I-D Exists
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Inter-Domain Routing                                           A. Retana
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                                R. White
Expires: May 22, 2014
                                                       November 18, 2013

                      BGP Custom Decision Process
                   draft-ietf-idr-custom-decision-04

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
   Task Force (IETF).  Note that other groups may also distribute
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   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 May 22, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  The BGP Cost Community  . . . . . . . . . . . . . . . . . . .   3
   4.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   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
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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.

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   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

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