IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery
RFC 5089

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Network Working Group                                   JL. Le Roux, Ed.
Request for Comments: 5089                                France Telecom
Category: Standards Track                               JP. Vasseur, Ed.
                                                       Cisco System Inc.
                                                              Y. Ikejiri
                                                      NTT Communications
                                                                R. Zhang
                                                                      BT
                                                            January 2008

                     IS-IS Protocol Extensions for
               Path Computation Element (PCE) Discovery

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   There are various circumstances where it is highly desirable for a
   Path Computation Client (PCC) to be able to dynamically and
   automatically discover a set of Path Computation Elements (PCEs),
   along with information that can be used by the PCC for PCE selection.
   When the PCE is a Label Switching Router (LSR) participating in the
   Interior Gateway Protocol (IGP), or even a server participating
   passively in the IGP, a simple and efficient way to announce PCEs
   consists of using IGP flooding.  For that purpose, this document
   defines extensions to the Intermediate System to Intermediate System
   (IS-IS) routing protocol for the advertisement of PCE Discovery
   information within an IS-IS area or within the entire IS-IS routing
   domain.

Le Roux, et al.             Standards Track                     [Page 1]
RFC 5089      IS-IS Protocol Extensions for PCE Discovery   January 2008

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................4
   3. Overview ........................................................5
      3.1. PCE Discovery Information ..................................5
      3.2. Flooding Scope .............................................5
   4. The IS-IS PCED Sub-TLV ..........................................5
      4.1. PCE-ADDRESS Sub-TLV ........................................6
      4.2. The PATH-SCOPE Sub-TLV .....................................7
      4.3. PCE-DOMAIN Sub-TLV .........................................9
      4.4. NEIG-PCE-DOMAIN Sub-TLV ...................................10
      4.5. PCE-CAP-FLAGS Sub-TLV .....................................10
   5. Elements of Procedure ..........................................11
   6. Backward Compatibility .........................................12
   7. IANA Considerations ............................................12
   8. Security Considerations ........................................12
   9. Manageability Considerations ...................................13
      9.1. Control of Policy and Functions ...........................13
      9.2. Information and Data Model ................................13
      9.3. Liveness Detection and Monitoring .........................13
      9.4. Verify Correct Operations .................................13
      9.5. Requirements on Other Protocols and Functional
           Components ................................................13
      9.6. Impact on Network Operations ..............................14
   10. Acknowledgments ...............................................14
   11. References ....................................................15
      11.1. Normative References .....................................15
      11.2. Informative References ...................................15

1.  Introduction

   [RFC4655] describes the motivations and architecture for a Path
   Computation Element (PCE)-based path computation model for
   Multi-Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS)
   Traffic Engineered Label Switched Paths (TE LSPs).  The model allows
   for the separation of the PCE from a Path Computation Client (PCC)
   (also referred to as a non co-located PCE) and allows for cooperation
   between PCEs (where one PCE acts as a PCC to make requests of the
   other PCE).  This relies on a communication protocol between a PCC
   and PCE, and also between PCEs.  The requirements for such a
   communication protocol can be found in [RFC4657], and the
   communication protocol is defined in [PCEP].

   The PCE architecture requires that a PCC be aware of the location of
   one or more PCEs in its domain, and, potentially, of PCEs in other
   domains, e.g., in the case of inter-domain TE LSP computation.