BGP Request for Advertising Candidate Path of Segment Routing TE Policies
draft-li-ldr-bgp-request-cp-sr-te-policy-00

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Network Working Group                                              Z. Li
Internet-Draft                                                        Li
Intended status: Standards Track                                  Huawei
Expires: January 9, 2020                                   July 08, 2019

    BGP Request for Advertising Candidate Path of Segment Routing TE
                                Policies
              draft-li-ldr-bgp-request-cp-sr-te-policy-00

Abstract

   An SR Policy is a set of candidate paths.  The headend of an SR
   Policy may learn multiple candidate paths for an SR Policy via a
   number of different mechanisms, e.g., CLI, NetConf, PCEP, or BGP.
   BGP distribute candidate paths has been defined in
   [I-D.ietf-idr-segment-routing-te-policy].  This document defines an
   extension of BGP to request BGP speaker(controller) advertise the
   candidate paths.  The goal is to unify the protocol when the
   candidate path of SR Policy provision is via BGP to reduce the
   network complexity and potential bugs cause by different protocol
   interactions.

Requirements 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 RFC 2119 [RFC2119].

Status of This Memo

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   This Internet-Draft will expire on January 9, 2020.

Li & Li                  Expires January 9, 2020                [Page 1]
Internet-Draft         BGP Trigger SR TE Policies              July 2019

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview of BGP UPDATE Message for Request SR TE policy
       candidate path advertising  . . . . . . . . . . . . . . . . .   3
   4.  BGP request UPDATE Message Encoding . . . . . . . . . . . . .   4
     4.1.  Extention of SR Policy NLRI . . . . . . . . . . . . . . .   4
     4.2.  New SR Policy and Tunnel Encapsulation Attribute  . . . .   5
     4.3.  New SR Policy Sub-TLVs  . . . . . . . . . . . . . . . . .   5
       4.3.1.  LSPA Sub-TLV  . . . . . . . . . . . . . . . . . . . .   5
       4.3.2.  SVEC Sub-TLV  . . . . . . . . . . . . . . . . . . . .   7
       4.3.3.  Metric Sub-TLV  . . . . . . . . . . . . . . . . . . .   8
       4.3.4.  Include Route Sub-TLV . . . . . . . . . . . . . . . .   9
       4.3.5.  Load-Balancing Sub-TLV  . . . . . . . . . . . . . . .  10
   5.  IANA  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  11
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   An SR Policy defined in [I-D.ietf-spring-segment-routing-policy] is a
   set of candidate paths.  The headend of an SR Policy may be informed
   by various means including: Configuration, PCEP[RFC8281] or
   BGP[I-D.ietf-idr-segment-routing-te-policy] . All these mechanisms
   are PCE/Controller initiated, but in some situations headend maybe
   want pull one or a set of candidate paths from PCE/Controller rather
   than get all information passively.  Actually PCEP can use request
   and reply messages defined in [RFC5440]to match this requirement but
   the mechanism is not clear when controller advertise candidate path
   via BGP protocol.
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