Segment Routing interworking with LDP
draft-ietf-spring-segment-routing-ldp-interop-11

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Network Working Group                                   A. Bashandy, Ed.
Internet-Draft                                                Individual
Intended status: Standards Track                        C. Filsfils, Ed.
Expires: October 12, 2018                                     S. Previdi
                                                     Cisco Systems, Inc.
                                                             B. Decraene
                                                            S. Litkowski
                                                                  Orange
                                                          April 10, 2018

                 Segment Routing interworking with LDP
            draft-ietf-spring-segment-routing-ldp-interop-11

Abstract

   A Segment Routing (SR) node steers a packet through a controlled set
   of instructions, called segments, by prepending the packet with an SR
   header.  A segment can represent any instruction, topological or
   service-based.  SR allows to enforce a flow through any topological
   path while maintaining per-flow state only at the ingress node to the
   SR domain.

   The Segment Routing architecture can be directly applied to the MPLS
   data plane with no change in the forwarding plane.  This document
   describes how Segment Routing operates in a network where LDP is
   deployed and in the case where SR-capable and non-SR-capable nodes
   coexist.

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

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   and may be updated, replaced, or obsoleted by other documents at any

Bashandy, et al.        Expires October 12, 2018                [Page 1]
Internet-Draft           Segment Routing and LDP              April 2018

   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 12, 2018.

Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  SR/LDP Ships-in-the-night coexistence . . . . . . . . . . . .   3
     2.1.  MPLS2MPLS, MPLS2IP and IP2MPLS co-existence . . . . . . .   5
   3.  Migration from LDP to SR  . . . . . . . . . . . . . . . . . .   6
   4.  SR and LDP Interworking . . . . . . . . . . . . . . . . . . .   7
     4.1.  LDP to SR . . . . . . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  LDP to SR Behavior  . . . . . . . . . . . . . . . . .   8
     4.2.  SR to LDP . . . . . . . . . . . . . . . . . . . . . . . .   8
       4.2.1.  SR to LDP Behavior  . . . . . . . . . . . . . . . . .  10
       4.2.2.  Interoperability of Multiple SRMSes and Prefix-SID
               advertisements  . . . . . . . . . . . . . . . . . . .  10
   5.  SR/LDP Interworking Use Cases . . . . . . . . . . . . . . . .  12
     5.1.  SR Protection of LDP-based Traffic  . . . . . . . . . . .  12
     5.2.  Eliminating Targeted LDP Session  . . . . . . . . . . . .  14
     5.3.  Guaranteed FRR coverage . . . . . . . . . . . . . . . . .  15
     5.4.  Inter-AS Option C, Carrier's Carrier  . . . . . . . . . .  16
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  17
   7.  Manageability Considerations  . . . . . . . . . . . . . . . .  17
     7.1.  SR and LDP co-existence . . . . . . . . . . . . . . . . .  17
     7.2.  Dataplane Verification  . . . . . . . . . . . . . . . . .  17
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  18
   10. Contributors' Addresses . . . . . . . . . . . . . . . . . . .  18
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  18