BGP Bestpath Selection Criteria Enhancement
draft-ietf-idr-bgp-bestpath-selection-criteria-12

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IDR Working Group                                           Rajiv Asati
Internet Draft                                            Cisco Systems
Updates: 4271 (if approved)
Intended status: Standards Track
Expires: December 5, 2019
                                                            June 5, 2019

                BGP Bestpath Selection Criteria Enhancement
           draft-ietf-idr-bgp-bestpath-selection-criteria-12.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 would 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.

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   This Internet-Draft will expire on December 5, 2019.

Copyright Notice

   Copyright (c) 2019 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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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........................................5
   6. IANA Considerations............................................5
   7. Acknowledgments................................................5
   8. Appendix.......................................................5
   9. References.....................................................8
   Author's Addresses................................................9

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

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   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",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3. Route Resolvability Condition - Modification

   This document proposes two amendments to 'Route Resolvability