RFC 5541 on Encoding of Objective Functions in the Path Computation Element Communication Protocol (PCEP)

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        RFC 5541

        Title:      Encoding of Objective Functions in 
                    the Path Computation Element Communication Protocol 
                    (PCEP) 
        Author:     JL. Le Roux, JP. Vasseur,
                    Y. Lee
        Status:     Standards Track
        Date:       June 2009
        Mailbox:    [e-mail], 
                    [e-mail], 
                    [e-mail]
        Pages:      23
        Characters: 45589
        Updates/Obsoletes/SeeAlso:   None

        I-D Tag:    draft-ietf-pce-of-06.txt

        URL:        http://www.rfc-editor.org/rfc/rfc5541.txt

The computation of one or a set of Traffic Engineering Label Switched
Paths (TE LSPs) in MultiProtocol Label Switching (MPLS) and
Generalized MPLS (GMPLS) networks is subject to a set of one or more
specific optimization criteria, referred to as objective functions
(e.g., minimum cost path, widest path, etc.).

In the Path Computation Element (PCE) architecture, a Path
Computation Client (PCC) may want a path to be computed for one or
more TE LSPs according to a specific objective function.  Thus, the
PCC needs to instruct the PCE to use the correct objective function.
Furthermore, it is possible that not all PCEs support the same set of
objective functions; therefore, it is useful for the PCC to be able to
automatically discover the set of objective functions supported by
each PCE.

This document defines extensions to the PCE communication Protocol
(PCEP) to allow a PCE to indicate the set of objective functions it
supports.  Extensions are also defined so that a PCC can indicate in
a path computation request the required objective function, and
a PCE can report in a path computation reply the objective
function that was used for path computation.

This document defines objective function code types for six
objective functions previously listed in the PCE requirements work,
and provides the definition of four new metric types that apply to a
set of synchronized requests.  [STANDARDS TRACK]

This document is a product of the Path Computation Element Working Group of the IETF.

This is now a Proposed Standard Protocol.

STANDARDS TRACK: 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.

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