BGP Bestpath Selection Criteria Enhancement
draft-ietf-idr-bgp-bestpath-selection-criteria-08

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Last updated 2017-10-10
Replaces draft-asati-idr-bgp-bestpath-selection-criteria
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IDR Working Group                                           Rajiv Asati
Internet Draft                                            Cisco Systems
Intended status: Standards Track
Expires: April 10, 2018
                                                        October 10, 2017

                BGP Bestpath Selection Criteria Enhancement
           draft-ietf-idr-bgp-bestpath-selection-criteria-08.txt

Abstract

   BGP specification [RFC4271] prescribes 'BGP next-hop reachability'
   as one of the key 'Route Resolvability Condition' that must be
   satisfied before the BGP bestpath candidate selection. This
   condition, however, may not be sufficient (as explained in the
   Appendix section) and desire further granularity.

   This document defines enhances the "Route Resolvability Condition"
   to facilitate the next-hop to be resolved in the chosen data plane.

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 10, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Internet-Draft BGP Bestpath Selection Criteria Enhanced October 10, 2017

   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
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Table of Contents

   1. Introduction...................................................2
   2. Specification Language.........................................3
   3. Route Resolvability Condition - Modification...................3
   4. Conclusions....................................................4
   5. Security Considerations........................................4
   6. IANA Considerations............................................5
   7. Acknowledgments................................................5
   8. Appendix.......................................................5
   9. References.....................................................7
   Author's Addresses................................................8

1. Introduction

   As per BGP specification [RFC4271], when a router receives a BGP
   path, BGP must qualify it as the valid candidate prior to the BGP
   bestpath selection using the 'Route Resolvability Condition'
   (section#9.1.2.1 of RFC4271]. After the path gets qualified as the
   bestpath candidate, it becomes eligible to be the bestpath, and may
   get advertised out to the neigbhor(s), if it became the bestpath.

   However, in BGP networks that utilize data plane protocol other than
   IP, such as MPLS [RFC3031] etc. to forward the received traffic
   towards the next-hop, the above qualification condition may not be
   sufficient. In fact, this may expose the BGP networks to experience
   traffic blackholing i.e. traffic loss, due to malfunctioning of the
   chosen data plane protocol to the next-hop. This is explained
   further in the Appendix section.

   This document defines further granularity to the "Route
   Resolvability Condition" by (a) resolving the BGP next-hop

Asati, Rajiv            Expires April 10, 2018                 [Page 2]
Internet-Draft BGP Bestpath Selection Criteria Enhanced October 10, 2017

   reachability in the forwarding database of a particular data plane
   protocol, and (b) optionally including the BGP next-hop "path
   availability" check.

   The goal is to enable BGP to select the bestpaths based on whether
   or not the corresponding nexthop can be resolved in the valid data
   plane.

2. Specification Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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