LDP Extensions to Support Maximally Redundant Trees
RFC 8320

Document Type RFC - Proposed Standard (February 2018; No errata)
Last updated 2018-02-22
Replaces draft-atlas-mpls-ldp-mrt
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Loa Andersson
Shepherd write-up Show (last changed 2017-03-03)
IESG IESG state RFC 8320 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Deborah Brungard
Send notices to tsaad@cisco.com, mpls-chairs@ietf.org
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                          A. Atlas
Request for Comments: 8320                               K. Tiruveedhula
Category: Standards Track                                      C. Bowers
ISSN: 2070-1721                                         Juniper Networks
                                                             J. Tantsura
                                                              Individual
                                                            IJ. Wijnands
                                                     Cisco Systems, Inc.
                                                           February 2018

          LDP Extensions to Support Maximally Redundant Trees

Abstract

   This document specifies extensions to the Label Distribution Protocol
   (LDP) to support the creation of Label Switched Paths (LSPs) for
   Maximally Redundant Trees (MRTs).  A prime use of MRTs is for unicast
   and multicast IP/LDP Fast Reroute, which we will refer to as
   "MRT-FRR".

   The sole protocol extension to LDP is simply the ability to advertise
   an MRT Capability.  This document describes that extension and the
   associated behavior expected for Label Switching Routers (LSRs) and
   Label Edge Routers (LERs) advertising the MRT Capability.

   MRT-FRR uses LDP multi-topology extensions, so three multi-topology
   IDs have been allocated from the MPLS MT-ID space.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8320.

Atlas, et al.                Standards Track                    [Page 1]
RFC 8320             LDP Extensions to Support MRTs        February 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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Atlas, et al.                Standards Track                    [Page 2]
RFC 8320             LDP Extensions to Support MRTs        February 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Overview of LDP Signaling Extensions for MRT  . . . . . . . .   6
     4.1.  MRT Capability Advertisement  . . . . . . . . . . . . . .   6
       4.1.1.  Interaction of MRT Capability and MT Capability . . .   7
       4.1.2.  Interaction of LDP MRT Capability with IPv4 and IPv6    8
     4.2.  Use of the Rainbow MRT MT-ID  . . . . . . . . . . . . . .   8
     4.3.  MRT-Blue and MRT-Red FECs . . . . . . . . . . . . . . . .   8
     4.4.  Interaction of MRT-Related LDP Advertisements with the
           MRT Topology and Computations . . . . . . . . . . . . . .   9
   5.  LDP MRT FEC Advertisements  . . . . . . . . . . . . . . . . .  10
     5.1.  MRT-Specific Behavior . . . . . . . . . . . . . . . . . .  10
       5.1.1.  ABR Behavior and Use of the Rainbow FEC . . . . . . .  10
       5.1.2.  Proxy-Node Attachment Router Behavior . . . . . . . .  11
     5.2.  LDP Protocol Procedures in the Context of MRT Label
           Distribution  . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.1.  LDP Peer in RFC 5036  . . . . . . . . . . . . . . . .  12
       5.2.2.  Next Hop in RFC 5036  . . . . . . . . . . . . . . . .  13
       5.2.3.  Egress LSR in RFC 5036  . . . . . . . . . . . . . . .  13
       5.2.4.  Use of Rainbow FEC to Satisfy Label Mapping Existence
               Requirements in RFC 5036  . . . . . . . . . . . . . .  15
       5.2.5.  Validating FECs in the Routing Table  . . . . . . . .  15
       5.2.6.  Recognizing New FECs  . . . . . . . . . . . . . . . .  15
       5.2.7.  Not Propagating Rainbow FEC Label Mappings  . . . . .  15
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   7.  Potential Restrictions on MRT-Related MT-ID Values Imposed by
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