LDP Downstream-on-Demand in Seamless MPLS
RFC 7032

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Internet Engineering Task Force (IETF)                  T. Beckhaus, Ed.
Request for Comments: 7032                           Deutsche Telekom AG
Category: Standards Track                                    B. Decraene
ISSN: 2070-1721                                                   Orange
                                                         K. Tiruveedhula
                                                        Juniper Networks
                                                 M. Konstantynowicz, Ed.
                                                              L. Martini
                                                     Cisco Systems, Inc.
                                                            October 2013

               LDP Downstream-on-Demand in Seamless MPLS

Abstract

   Seamless MPLS design enables a single IP/MPLS network to scale over
   core, metro, and access parts of a large packet network
   infrastructure using standardized IP/MPLS protocols.  One of the key
   goals of Seamless MPLS is to meet requirements specific to access
   networks including high number of devices, device position in network
   topology, and compute and memory constraints that limit the amount of
   state access devices can hold.  This can be achieved with LDP
   Downstream-on-Demand (DoD) label advertisement.  This document
   describes LDP DoD use cases and lists required LDP DoD procedures in
   the context of Seamless MPLS design.

   In addition, a new optional TLV type in the LDP Label Request message
   is defined for fast-up convergence.

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 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7032.

Beckhaus, et al.             Standards Track                    [Page 1]
RFC 7032                         LDP DoD                    October 2013

Copyright Notice

   Copyright (c) 2013 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
   (http://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.

Beckhaus, et al.             Standards Track                    [Page 2]
RFC 7032                         LDP DoD                    October 2013

Table of Contents

   1. Introduction ....................................................4
   2. Reference Topologies ............................................6
      2.1. Access Topologies with Static Routing ......................6
      2.2. Access Topologies with Access IGP .........................10
   3. LDP DoD Use Cases ..............................................11
      3.1. Initial Network Setup .....................................12
           3.1.1. AN with Static Routing .............................12
           3.1.2. AN with Access IGP .................................13
      3.2. Service Provisioning and Activation .......................14
      3.3. Service Changes and Decommissioning .......................16
      3.4. Service Failure ...........................................17
      3.5. Network Transport Failure .................................17
           3.5.1. General Notes ......................................17
           3.5.2. AN Failure .........................................18
           3.5.3. AN/AGN Link Failure ................................19
           3.5.4. AGN Failure ........................................20
           3.5.5. AGN Network-Side Reachability Failure ..............20
   4. LDP DoD Procedures .............................................20
      4.1. LDP Label Distribution Control and Retention Modes ........21
      4.2. LDP DoD Session Negotiation ...............................23
      4.3. Label Request Procedures ..................................23
           4.3.1. Access LSR/ABR Label Request .......................23
           4.3.2. Label Request Retry ................................24
      4.4. Label Withdraw ............................................25
      4.5. Label Release .............................................26