Signaling Composite Candidate Path of SR Policy using BGP-LS
draft-li-idr-bgpls-sr-policy-composite-path-00

Document Type Active Internet-Draft (individual)
Authors Hao Li  , Mengxiao Chen  , Changwang Lin
Last updated 2021-02-02
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Network Working Group                                              H. Li
Internet-Draft                                                   M. Chen
Intended status: Standards Track                                  C. Lin
Expires: August 6, 2021                                              H3C
                                                        February 2, 2021

      Signaling Composite Candidate Path of SR Policy using BGP-LS
             draft-li-idr-bgpls-sr-policy-composite-path-00

Abstract

   Segment Routing is a source routing paradigm that explicitly
   indicates the forwarding path for packets at the ingress node.  An SR
   Policy is associated with one or more candidate paths, and each
   candidate path is either dynamic, explicit or composite.  This
   document specifies the extensions to BGP Link State (BGP-LS) to carry
   composite candidate path information in the advertisement of an SR
   policy.

Status of This Memo

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   This Internet-Draft will expire on August 6, 2021.

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   include Simplified BSD License text as described in Section 4.e of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  BGP-LS Extensions for Composite Candidate Path  . . . . . . .   3
     3.1.  Constituent SR Policy TLV . . . . . . . . . . . . . . . .   3
   4.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   As described in [RFC7752], BGP Link State (BGP-LS) provides a
   mechanism by which link-state and TE information can be collected
   from networks and shared with external components using the BGP
   routing protocol.

   Segment routing (SR) [RFC8402] is a source routing paradigm that
   explicitly indicates the forwarding path for packets at the ingress
   node.  The ingress node steers packets into a specific path according
   to the Segment Routing Policy (SR Policy) as defined in
   [I-D.ietf-spring-segment-routing-policy].

   An SR Policy is associated with one or more candidate paths.  A
   composite candidate path acts as a container for grouping of SR
   Policies.  As described in section 2.2 in
   [I-D.ietf-spring-segment-routing-policy], the composite candidate
   path construct enables combination of SR Policies, each with explicit
   candidate paths and/or dynamic candidate paths with potentially
   different optimization objectives and constraints, for a load-
   balanced steering of packet flows over its constituent SR Policies.

   [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-LS updates.  This document extends it to
   provide some extra information to carry composite candidate path
   information in the BGP-LS advertisement.

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2.  Terminology

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