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

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.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

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