Signalling ERLD using BGP-LS
draft-vandevelde-idr-bgp-ls-segment-routing-rld-03

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Last updated 2017-07-19 (latest revision 2017-04-24)
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IDR Working Group                                   G. Van de Velde, Ed.
Internet-Draft                                             W. Henderickx
Intended status: Standards Track                                M. Bocci
Expires: October 26, 2017                                          Nokia
                                                                K. Patel
                                                                  Arrcus
                                                          April 24, 2017

                      Signalling ERLD using BGP-LS
           draft-vandevelde-idr-bgp-ls-segment-routing-rld-03

Abstract

   This document defines the attributes to use for BGP-LS to expose a
   node or link ERLD "Entropy capable Readable Label Depth" to a
   centralised controller (PCE/SDN).

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 [1].

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   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on October 26, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   4.  ERLD support by a node  . . . . . . . . . . . . . . . . . . .   3
   5.  ERLD support by a link  . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   When Segment Routing tunnels are computed by a centralised
   controller, it is beneficial that the controller knows the ERLD
   (Entropy capable Readable Label Depth) of each node or link a tunnel
   traverses.  A network node signalling an ERLD MUST support the
   ability to read the signalled number of labels before any action is
   done upon the packet and SHOULD support entropy awareness found
   within the signalled ERLD depth.

   ERLD awareness of each node and link will allow a network SDN
   controller to influence the path used for each tunnel.  The SDN
   controller may for example only create tunnels with a label stack
   smaller or equal as the ERLD of each node and link on the path.  This
   will allow the network to behave accordingly (e.g.  make use of
   Entropy Labels to improve ECMP) upon the imposed Segment Routing
   labels on each packet.

   This document describes how to use BGP-LS to expose the ERLD of a
   node.

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