Subject: [Pce] Path Computation Element Working Group in the IETF

From: "Adrian Farrel" <[email-masked]>
Date: Sat, 5 Mar 2005 09:27:11 -0000

To: Mr. Yoichi Maeda, chairman ITU-T Study Group 15
Cc: Mr. Scott Bradner, IETF liaison coordinator with the ITU-T
      Alex Zinin and Bill Fenner, IETF Routing Area Directors
From: Adrian Farrel and JP Vasseur, IETF PCE working group chairs
Subject: Path Computation Element Working Group in the IETF
For: Action
Deadline: 1st April 2005

Dear Mr. Maeda,

We would like to inform you and Study Group 15 of the creation of a new
working group within the IETF to work on the Path Computation Element
(PCE). The charter of this working group is shown below and provides a
brief definition of the PCE. Further understanding of what the IETF means
by PCE can be found in
http://www.ietf.org/internet-drafts/draft-ash-pce-architecture-01.txt
although this should be seen as a work in progress.

We believe that some work may already have been carried out within the
ITU-T (probably within SG15) on determining a functional architecture for
a similar logical entity - that is, for a logically distinct control plane
component that is responsible for performing path computations. We are
anxious to leverage this work so that we can produce a solution that most
closely matches the needs of the ITU-T community, so that we do not waste
effort re-inventing anything, and so that we can move our own work
forwards as rapidly as possible.

Could you please pass this liaison to all interested parties within the
ITU-T and particularly to the Questions that may have worked on a similar
topic with a request that they give us pointers to all related and
previous work. Once we have established direct contact with the relevant
groups we will continue to liaise our progress to them and will solicit
their opinions especially with respect to architecture and functional
requirements.

Thank you for your help.

Best regards,
Adrian Farrel and JP Vasseur

=====
Path Computation Element Working Group Charter

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 obustness 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:
Feb 05  Submit first draft of PCE architecture document
Feb 05  Submit first draft of PCE discovery requirements and protocol
extensions
        documents
Apr 05  Submit first draft of the PCE communication protocol requirements
May 05  Submit first draft of the definition of objective metrics
Jul 05  Submit first draft of the PCE communication protocol specification
Aug 05  Submit PCE architecture specification to the IESG to be considered
as
        Informational RFC
Nov 05  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)
Nov 05  Submit first draft of the MIB module for the PCE protocol
Dec 05  Submit PCE communication protocol requirements to the IESG to be
considered
        as an Informational RFC
Dec 05  Submit PCE discovery protocol extensions specifications to the
IESG to be
        considered as a Proposed Standard
Dec 05  Submit PCE communication protocol specification to the IESG to be
considered
        as a Proposed Standard
Feb 06  Submit the applicability and metrics documents to the IESG to be
considered as
        Informational RFC
Feb 06  Evaluate WG progress, recharter or close

_______________________________________________
Pce mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/pce

---

From: Yoichi Maeda <[email-masked]>
Date: Sat, 19 Mar 2005 23:07:22 +0900

Dear Adrian;

Thank you for your information.  I am sorry for my delayed reply to your
initial e-mail. I have been in Geneva for two weeks.

As for your question on the PCE-WG issue, I have surveyed and identified
that Q.6, Q.12 and Q.14 in SG15 will be relevant for your PCE issues.  I
have transferred your information to each Questions and asked their
replies.
   ****
6/15 Characteristics of optical systems for terrestrial transport networks 
12/15 Transport network architectures 
14/15 Management and control of transport systems and equipment 
   ****
We are interested in the study and we will appoint a liaison officer in
order to follow the activities of PCE-WG if required.  I hope we can
send a Liaison Statement to you before April.

Best regards,

Yoichi

On Sat, 5 Mar 2005 09:27:11 -0000

> Feb 06  Evaluate WG progress, recharter or close

******************************************************
Yoichi MAEDA
   NTT Corporation, Access Service Systems Laboratories,
   Chairman ITU-T Study Group 15
Address: 1-6 Nakase, Mihama-ku, Chiba-shi, 261-0023, JAPAN
Tel:  +81-43-211-3274,   Fax: +81-43-211-8282
E-mail:  [email-masked]
*******************************************************