Applicability of the Path Computation Element (PCE) to Point-to-Multipoint (P2MP) MPLS and GMPLS Traffic Engineering (TE)
RFC 5671

Network Working Group                                        S. Yasukawa
Request for Comments: 5671                                           NTT
Category: Informational                                   A. Farrel, Ed.
                                                      Old Dog Consulting
                                                            October 2009

         Applicability of the Path Computation Element (PCE) to
   Point-to-Multipoint (P2MP) MPLS and GMPLS Traffic Engineering (TE)

Abstract

   The Path Computation Element (PCE) provides path computation
   functions in support of traffic engineering in Multiprotocol Label
   Switching (MPLS) and Generalized MPLS (GMPLS) networks.

   Extensions to the MPLS and GMPLS signaling and routing protocols have
   been made in support of point-to-multipoint (P2MP) Traffic Engineered
   (TE) Label Switched Paths (LSPs).

   This document examines the applicability of PCE to path computation
   for P2MP TE LSPs in MPLS and GMPLS networks.  It describes the
   motivation for using a PCE to compute these paths and examines which
   of the PCE architectural models are appropriate.

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

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Yasukawa & Farrel            Informational                      [Page 1]
RFC 5671             PCE for P2MP MPLS and GMPLS TE         October 2009

Table of Contents

   1. Introduction ....................................................2
   2. Architectural Considerations ....................................4
      2.1. Offline Computation ........................................4
      2.2. Online Computation .........................................4
           2.2.1. LSR Loading .........................................5
           2.2.2. PCE Overload ........................................6
           2.2.3. PCE Capabilities ....................................6
   3. Fragmenting the P2MP Tree .......................................7
   4. Central Replication Points ......................................8
   5. Reoptimization and Modification .................................9
   6. Repair .........................................................10
   7. Disjoint Paths .................................................11
   8. Manageability Considerations ...................................11
      8.1. Control of Function and Policy ............................11
      8.2. Information and Data Models ...............................11
      8.3. Liveness Detection and Monitoring .........................12
      8.4. Verifying Correct Operation ...............................12
      8.5. Requirements on Other Protocols and Functional
           Components ................................................12
      8.6. Impact on Network Operation ...............................13
   9. Security Considerations ........................................13
   10. Acknowledgments ...............................................13
   11. References ....................................................13
      11.1. Normative References .....................................13
      11.2. Informative References ...................................13

1.  Introduction

   The Path Computation Element (PCE) defined in [RFC4655] is an entity
   that is capable of computing a network path or route based on a
   network graph and of applying computational constraints.  The
   intention is that the PCE is used to compute the path of Traffic
   Engineered Label Switched Paths (TE LSPs) within Multiprotocol Label
   Switching (MPLS) and Generalized MPLS (GMPLS) networks.

   [RFC4655] defines various deployment models that place PCEs
   differently within the network.  The PCEs may be collocated with the
   Label Switching Routers (LSRs), may be part of the management system
   that requests the LSPs to be established, or may be positioned as one
   or more computation servers within the network.

   Requirements for point-to-multipoint (P2MP) MPLS TE LSPs are