BGP extensions of SR policy for path protection
draft-lp-idr-sr-path-protection-00

Document Type Active Internet-Draft (individual)
Authors Liu Yao  , Shaofu Peng 
Last updated 2020-10-14
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IDR WG                                                          Yao. Liu
Internet-Draft                                              Shaofu. Peng
Intended status: Standards Track                         ZTE Corporation
Expires: April 17, 2021                                 October 14, 2020

            BGP extensions of SR policy for path protection
                   draft-lp-idr-sr-path-protection-00

Abstract

   This document proposes extensions of BGP in order to provide path
   protection within a candidate path when delivering SR policy.  And it
   also extends BGP-LS to provide some extra information of the segment
   list in a candidate path in the advertisement.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on April 17, 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  BGP Extensions for Advertising Segment List . . . . . . . . .   3
     2.1.  Extensions of Segment List sub-TLV  . . . . . . . . . . .   3
     2.2.  List Identifier Sub-TLV . . . . . . . . . . . . . . . . .   3
       2.2.1.  List Protection Sub-TLV . . . . . . . . . . . . . . .   4
   3.  BGP-LS Extensions for Distributing Segment List States  . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Segment Routing [RFC8402] allows a headend node to steer a packet
   flow along any path.

   [I-D.ietf-spring-segment-routing-policy] details the concepts of SR
   Policy and steering into an SR Policy.  An SR Policy is a set of
   candidate paths, each consisting of one or more segment lists.  The
   headend of an SR Policy may learn multiple candidate paths for an SR
   Policy.

   When SR policies are involved and a strict compliance of the policy
   is required, an end-to-end protection should be preferred over a
   local repair mechanism.

   Candidate path can be used for path protection, that is, the lower
   preference candidate path may be designated as the backup for a
   specific or all (active) candidate path(s).

   Despite using candidate path for protection, protection at segment
   list level within an candidate path is also useful.

   [I-D.ietf-idr-segment-routing-te-policy] specifies BGP extensions for
   the advertisement of SR Policies and each candidate path is carried
   in an NLRI, if candidate path is used for protection ,the BGP origin
   must generate multiple NLRIs.  If protection at segment list level is
   possible, only one NLRI is needed which makes the advertisement more
   simple.

   On the other hand, protection in and between candidate path can be
   combined together to provide a more comprehensive protection
   mechanism.

   This document proposes extensions of BGP in order to provide path
   protection in an candidate path when delivering SR policy.

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   [I-D.ietf-idr-te-lsp-distribution] describes a mechanism to collect
   the SR policy information that is locally available in a node and
   advertise it into BGP Link State (BGP-LS) updates.  This document
   also extends it to provide some extra information of the segment list
   in a candidate path in the BGP-LS advertisement.
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