Path Computation Element (PCE) Communication Protocol (PCEP)
RFC 5440

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Network Working Group                                   JP. Vasseur, Ed.
Request for Comments: 5440                                 Cisco Systems
Category: Standards Track                               JL. Le Roux, Ed.
                                                          France Telecom
                                                              March 2009

      Path Computation Element (PCE) Communication Protocol (PCEP)

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.

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Vasseur & Le Roux           Standards Track                     [Page 1]
RFC 5440                          PCEP                        March 2009

Abstract

   This document specifies the Path Computation Element (PCE)
   Communication Protocol (PCEP) for communications between a Path
   Computation Client (PCC) and a PCE, or between two PCEs.  Such
   interactions include path computation requests and path computation
   replies as well as notifications of specific states related to the
   use of a PCE in the context of Multiprotocol Label Switching (MPLS)
   and Generalized MPLS (GMPLS) Traffic Engineering.  PCEP is designed
   to be flexible and extensible so as to easily allow for the addition
   of further messages and objects, should further requirements be
   expressed in the future.

Vasseur & Le Roux           Standards Track                     [Page 2]
RFC 5440                          PCEP                        March 2009

Table of Contents

   1. Introduction ....................................................5
      1.1. Requirements Language ......................................5
   2. Terminology .....................................................5
   3. Assumptions .....................................................6
   4. Architectural Protocol Overview (Model) .........................7
      4.1. Problem ....................................................7
      4.2. Architectural Protocol Overview ............................7
           4.2.1. Initialization Phase ................................8
           4.2.2. Session Keepalive ...................................9
           4.2.3. Path Computation Request Sent by a PCC to a PCE ....10
           4.2.4. Path Computation Reply Sent by The PCE to a PCC ....11
           4.2.5. Notification .......................................12
           4.2.6. Error ..............................................14
           4.2.7. Termination of the PCEP Session ....................14
           4.2.8. Intermittent versus Permanent PCEP Session .........15
   5. Transport Protocol .............................................15
   6. PCEP Messages ..................................................15
      6.1. Common Header .............................................16
      6.2. Open Message ..............................................16
      6.3. Keepalive Message .........................................18
      6.4. Path Computation Request (PCReq) Message ..................19
      6.5. Path Computation Reply (PCRep) Message ....................20
      6.6. Notification (PCNtf) Message ..............................21
      6.7. Error (PCErr) Message .....................................22
      6.8. Close Message .............................................23
      6.9. Reception of Unknown Messages .............................23
   7. Object Formats .................................................23
      7.1. PCEP TLV Format ...........................................24