Path Computation Element BOF (pce)

Thursday, August 5 at 1300-1500
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CHAIRS: JP Vasseur (jvasseur@cisco.com) 
        Adrian Farrel (adrian@olddog.co.uk) 

DESCRIPTION:

In certain MPLS TE networks it may be beneficial or desirable to have path 
computation performed by a distinct node (termed the Path Computation 
Element  (PCE) that is not the LSR that needs to know the path. This BOF 
examines the scope of such function, what extensions to existing protocols 
might required, what additional protocols may need to be developed, and 
whether there is cuase and support for this work within the IETF.

AGENDA:

1) Introduction, admin, statement of objectives of the BOF (10 minutes)
2) Overview of PCE-based LSP Path computation (10 minutes)
         - terminology
         - dichotomy (centralized versus distributed, statefull versus 
           stateless, ...)
3) Requirements for PCE-based path computation (5 minutes)
         - for intra-area TE LSP (packet and non packet LSP, multiple 
criteria optimization techniques, online/offline)
         - for inter-area and inter-AS TE (shared information or 
           collaborative computation)
4) Functional requirements of a PCE-based path computation system  (10 minutes)
         - Framework,
         - Path computation model
         - discovery of PCEs within a network
         - distribution of TE information to PCEs
         - LSR-PCE communication
         - Monitoring and Management (MIBs)
         - Policy/Security/Confidentiality in the context of inter-providers
5) Current status of drafts and early implementations (10 minutes)
6) Why should this be IETF work? (5 minutes)
         - CCAMP or new Working Group?
         - Is this work limited to MPLS-TE? What about BGP route servers?
7) Proposed charter (see below) (10 minutes)
8) Open discussion (50 minutes)
9) Summary and conclusions (10 minutes)

Proposed WG Charter

Organizational Overview
The PCE working group coordinates the work within the IETF of defining the 
operation of path computation elements within the Internet. Path 
computation elements are responsible for computing paths through IP 
networks for uses such as traffic engineering so that a prime consumer of 
such paths might be an MPLS-TE LSR. Areas of responsibility will include 
the collection of attributes relevant to the computation of paths, the 
discovery by LSRs of available path computation elements, the communication 
with LSRs for the request of path computation, the collaboration between 
path computation elements within the network, and analysis of path 
computation algorithms with a view to ensuring consistency between computed 
paths. The working group will work closely with many working groups in the 
Routing Area including the OSPF, IS-IS, IDR, MPLS and CCAMP working groups.

Working Group Scope
The PCE working group scope includes:
- Definition  of Generalized Traffic Engineered LSP paths computation 
  techniques involving Path Computation Element(s). This includes the intra 
  IGP area, inter IGP area, inter-AS and inter-provider TE LSPs path 
  computation for Point-to-Point, Point-to-Multipoint and 
  Multipoint-to-Multipoint TE LSPs.
- Definition of protocol-independent metrics and constraints defining path 
  quality measurement criteria, algorithm complexity and scalability criteria 
  related to path computation techniques.
- Definition of requirements for communication between LSRs and PCEs 
  including routing extensions in support of PCE discovery techniques within 
  an IGP area and across multiple IGP areas, ASes and Provider networks, and 
  including the development of new protocols or protocol extensions for 
  requesting path computation and supplying responses. Any protocol 
  extensions will developed in conjunction with the working groups in charge 
  of the specific protocols.
- Specification of routing (OSPF, ISIS, BGP) and signalling extensions 
  (RSVP-TE) required by PCE-based path computation techniques. The extensions 
  will developed in conjunction with the working groups in charge of the 
  specific protocols.
- Specification of requirements and protocol extensions related to the 
  policy, security and confidentiality aspects of PCE-based path computation 
  techniques involving PCEs of multiple Providers.
- Definition of MIBs, management procedures related to the protocol 
  extensions defined by the WG

In doing this work, the WG will closely work with at least the following 
other WGs: CCAMP, MPLS, ISIS, OSPF, IDR. The WG will also cooperate with 
the ITU-T  and OIF.

Goals and Milestones

Dates for milestones to be decided later.

         Post strawman WG goals and charter.

         Submit WG document defining the framework and applicability of the 
         PCE model.

         Select a single candidate protocol from communication between LSRs 
         and PCEs.

         Submit document(s) that define various path computation models

         Submit an analysis document examining the requirements for coherent
         computation techniques and the implication of cooperation between 
         PCEs.

         Submit a document defining the protocol for communication between 
         LSRs and PCEs.

         Submit document(s) defining extensions to routing and signalling 
         protocols necessary to support the use of a PCE model within MPLS 
         networks.

         Submit a document defining MIB modules for modeling and management 
         of PCE systems.