BGP Extension for SR-MPLS Entropy Label Position
draft-zhou-idr-bgp-srmpls-elp-02

Document Type Active Internet-Draft (individual)
Authors Liu Yao  , Shaofu Peng 
Last updated 2021-02-22
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IDR Working Group                                               Yao. Liu
Internet-Draft                                              Shaofu. Peng
Intended status: Standards Track                               ZTE Corp.
Expires: August 26, 2021                               February 22, 2021

            BGP Extension for SR-MPLS Entropy Label Position
                    draft-zhou-idr-bgp-srmpls-elp-02

Abstract

   This document proposes extensions for BGP to indicate the entropy
   label position in the SR-MPLS label stack when distributing SR Policy
   candidate paths.

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   This Internet-Draft will expire on August 26, 2021.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Terminology and Acronyms  . . . . . . . . . . . . . . . .   3
   3.  Entropy Labels in SR-MPLS Scenario with a Controller  . . . .   3
   4.  BGP Extensions  . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Operations  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Segment Routing (SR) leverages the source routing paradigm.  Segment
   Routing can be instantiated on MPLS data plane which is referred to
   as SR-MPLS [RFC8660].  SR-MPLS leverages the MPLS label stack to
   construct the SR path.

   Entropy labels (ELs) [RFC6790] are used in the MPLS data plane to
   provide entropy for load-balancing.  The idea behind the entropy
   label is that the ingress router computes a hash based on several
   fields from a given packet and places the result in an additional
   label named "entropy label".  Then, this entropy label can be used as
   part of the hash keys used by an LSR.  Using the entropy label as
   part of the hash keys reduces the need for deep packet inspection in
   the LSR while keeping a good level of entropy in the load-balancing.

   [RFC8662] proposes to use entropy labels for SR-MPLS networks and
   mutiple < ELI, EL> pairs may be inserted in the SR-MPLS label stack.
   The ingress node may decide the number and position of the ELI/ELs
   which need to be inserted into the label stack, that is termed as ELP
   (Entropy Label Position).  In some cases, centralized controllers are
   used to perform the TE path computation for intra or inter-domain
   scenarios, thus it is also the responsibility of the controller to
   calculate ELP and inform it to the headend of the SR-TE path.

   [I-D.ietf-idr-segment-routing-te-policy] defines the specific process
   of how the controller/PCE in the SR network passes the path
   calculation result of the SR-TE policy to the headend of the network
   through BGP.

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   This document proposes extensions for BGP to indicate the ELP in the
   segment list when distribute SR Policy candidate paths using BGP for
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