Path Computation Element BOF (pce)

Thursday, August 5 at 1300-1500
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CHAIRS: JP Vasseur ([email protected])
       Adrian Farrel ([email protected])

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.

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