Path Computation Element (pce)
------------------------------

Charter
Last Modified: 2007-09-26

Current Status: Active Working Group

Chair(s):
    JP Vasseur  <[email protected]>
    Adrian Farrel  <[email protected]>

Routing Area Director(s):
    Ross Callon  <[email protected]>
    David Ward  <[email protected]>

Routing Area Advisor:
    Ross Callon  <[email protected]>

Mailing Lists:
    General Discussion:[email protected]
    To Subscribe:      [email protected]
        In Body:       subscribe pce
    Archive:           http://www.ietf.org/mail-archive/web/pce/

Description of Working Group:

The PCE Working Group is chartered to specify a Path Computation
Element
(PCE) based architecture for the computation of paths for MPLS and
GMPLS
Traffic Engineering LSPs.

In this architecture path computation does not occur on the head-end
(ingress) LSR, but on some other path computation entity that may
physically not be located on the head-end LSR.

The PCE WG will work on application of this model within a single
domain
or within a small group of domains (where a domain is a layer, IGP area
or Autonomous System with limited visibility from the head-end LSR).
At this time, applying this model to large groups of domains such as
the
Internet is not thought to be possible, and the PCE WG will not spend
energy on that topic.

The WG will specify a protocol for communication between LSRs (termed
Path Computation Clients - PCCs) and PCEs, and between cooperating
PCEs.
This protocol will be capable of representing requests for path
computation including a full set of constraints, will be able to return
multiple paths, and will include security mechanisms such as
authentication and confidentiality.

The WG will determine requirements for extensions to existing routing
and signaling protocols in support of PCE discovery and signaling of
inter-domain paths. Candidate protocols for extensions are RSVP-TE,
OSPF-TE, ISIS-TE and BGP. Any necessary extensions will be produced in
collaboration with the Working Groups responsible for the protocols.

The Working Group will also work on the definition of metrics to
evaluate path quality, scalability, responsiveness and robustness of
path computation models.

Work Items:

- Functional specification of MPLS and GMPLS Traffic Engineered LSP
path
computation models involving Path Computation Element(s). This
includes the case of computing the paths of intra and inter-domain
TE LSPs. Such path computation includes the generation of primary,
protection and recovery paths, as well as computations for
(local/global) reoptimization and load balancing. The WG will address
the inter-area (single IGP domain) scenario first. WG progress will be
evaluated before inter-AS related work is started.

- Specification of the PCE-based architecture.

- Specification of requirements and protocol extensions related to
the policy, and security aspects of PCE-based path computation
involving
PCEs of multiple administrative entities.

- In cooperation with protocol specific Working Group (OSPF, ISIS, IDR,
MPLS, CCAMP), development of routing (OSPF, ISIS, BGP) and LSP
signaling (RSVP-TE) extensions required to support PCE-based path
computation models.

- Specification of techniques in support of PCE discovery within and
across domains. Where such techniques result in the extensions of
existing protocols (e.g., OSPF, ISIS or BGP), this work will be done in
conjunction with the appropriate WGs.

- Specification of a new communication protocol for use between a PCC
and a PCE, and between PCEs. A single protocol will be selected from
among candidates that include the existing protocols defined in other
WGs.

- Definition of objective metrics to evaluate various criteria such as
the measurement of path quality, response time, robustness and
scalability of path computation models.

Review of the document "Requirements for path computation element in
GMPLS inter-domain networks" produced by the CCAMP WG.

Goals and Milestones:

  Done         Submit first draft of PCE architecture document

  Done         Submit first draft of PCE discovery requirements and protocol
               extensions documents

  Done         Submit first draft of the PCE communication protocol
               requirements

  May 2005       Submit first draft of the definition of objective metrics

  Done         Submit first draft of the PCE communication protocol
               specification

  Done         Submit PCE architecture specification to the IESG to be
               considered as Informational RFC

  Nov 2005       Submit first draft of applicability statement (describing the
               processes and procedures for the use of the PCE architecture,
               protocols and protocol extensions for inter-area MPLS and GMPLS
               Traffic Engineering)

  Done         Submit first draft of the MIB module for the PCE protocol

  Done         Submit PCE communication protocol requirements to the IESG to
               be considered as an Informational RFC

  Done         Submit PCE discovery protocol extensions specifications to the
               IESG to be considered as a Proposed Standard

  Dec 2005       Submit PCE communication protocol specification to the IESG to
               be considered as a Proposed Standard

  Feb 2006       Submit the applicability and metrics documents to the
               considered as Informational RFCIESG to be

  Feb 2006       Evaluate WG progress, recharter or close


Internet-Drafts:

Posted Revised         I-D Title   <Filename>
------ ------- --------------------------------------------
Nov 2005 Mar 2008   <draft-ietf-pce-pcep-12.txt>
               Path Computation Element (PCE) Communication Protocol (PCEP)

Nov 2005 Nov 2007   <draft-ietf-pce-inter-layer-req-06.txt>
               PCC-PCE Communication and PCE Discovery Requirements for
               Inter-Layer Traffic Engineering

Apr 2006 Jan 2008   <draft-ietf-pce-inter-layer-frwk-06.txt>
               Framework for PCE-Based Inter-Layer MPLS and GMPLS Traffic
               Engineering

Aug 2006 Nov 2007   <draft-ietf-pce-policy-enabled-path-comp-03.txt>
               Policy-Enabled Path Computation Framework

Aug 2006 Feb 2008   <draft-ietf-pce-interas-pcecp-reqs-04.txt>
               Inter-AS Requirements for the Path Computation Element
               Communication Protocol (PCECP)

Aug 2006 Feb 2008   <draft-ietf-pce-brpc-07.txt>
               A Backward Recursive PCE-based Computation (BRPC) procedure to
               compute shortest inter-domain Traffic Engineering Label
               Switched Paths

Dec 2006 Feb 2008   <draft-ietf-pce-disc-mib-02.txt>
               Definitions of Managed Objects for Path Computation Element
               Discovery

Jan 2007 Feb 2008   <draft-ietf-pce-manageability-requirements-03.txt>
               Inclusion of Manageability Sections in PCE Working Group Drafts

Apr 2007 Mar 2008   <draft-ietf-pce-pcep-xro-05.txt>
               Extensions to the Path Computation Element Communication
               Protocol (PCEP) for Route Exclusions

May 2007 Feb 2008   <draft-ietf-pce-path-key-02.txt>
               Preserving Topology Confidentiality in Inter-Domain Path
               Computation Using a Key-Based Mechanism

Jun 2007 Feb 2008   <draft-ietf-pce-global-concurrent-optimization-02.txt>
               Path Computation Element Communication Protocol (PCECP)
               Requirements and Protocol Extensions In Support of Global
               Concurrent Optimization

Sep 2007 Feb 2008   <draft-ietf-pce-of-02.txt>
               Encoding of Objective Functions in Path Computation Element
               communication Protocol (PCEP)

Sep 2007 Feb 2008   <draft-ietf-pce-monitoring-01.txt>
               A set of monitoring tools for Path Computation Element based
               Architecture

Oct 2007 Oct 2007   <draft-ietf-pce-dste-00.txt>
               Diff-Serv Aware Class Type Object for Path Computation Element
               Communication Protocol

Feb 2008 Feb 2008   <draft-ietf-pce-inter-layer-ext-00.txt>
               Extensions to the Path Computation Element communication
               Protocol (PCEP) for Inter-Layer MPLS and GMPLS Traffic
               Engineering

Request For Comments:

 RFC   Stat Published     Title
------- -- ----------- ------------------------------------
RFC4655 I    Aug 2006    A Path Computation Element (PCE) Based Architecture

RFC4657 I    Sep 2006    Path Computation Element (PCE) Communication Protocol
                      Generic Requirements

RFC4674 I    Oct 2006    Requirements for Path Computation Element (PCE)
                      Discovery

RFC4927 I    Jun 2007    PCE Communication Protocol (PCECP) Specific Requirements
                      for Inter-Area Multi Protocol Label Switching (MPLS) and
                      Generalized MPLS (GMPLS) Traffic Engineering

RFC5089 PS   Jan 2008    IS-IS Protocol Extensions for Path Computation Element
                      (PCE) Discovery

RFC5088 PS   Jan 2008    OSPF Protocol Extensions for Path Computation Element
                      (PCE) Discovery

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