Subject: [Pce] I-D Action:draft-ietf-pce-global-concurrent-optimization-04.txt

From: [email-masked]
Date: Mon, 14 Jul 2008 08:30:02 -0700 (PDT)

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Path Computation Element Working Group of the IETF.

	Title           : Path Computation Element Communication Protocol (PCECP) Requirements and Protocol Extensions In Support of Global Concurrent Optimization
	Author(s)       : Y. Lee, et al.
	Filename        : draft-ietf-pce-global-concurrent-optimization-04.txt
	Pages           : 30
	Date            : 2008-07-14

The Path Computation Element (PCE) is a network component,
application, or node that is capable of performing path computations
at the request of Path Computation Clients (PCCs).  The PCE is
applied in Multiprotocol Label Switching Traffic Engineering
(MPLS-TE) networks and in Generalized MPLS (GMPLS) networks to
determine the routes of Label Switched Paths (LSPs) through the
network.  In this context a PCC may be a Label Switching Router
(LSR), a Network Management System (NMS), or another PCE.  The Path
Computation Element Communication Protocol (PCEP) is specified for
communications between PCCs and PCEs, and between cooperating PCEs.

When computing or re-optimizing the routes of a set of LSPs through a
network it may be advantageous to perform bulk path computations in
order to avoid blocking problems and to achieve more optimal network-
wide solutions.  Such bulk optimization is termed Global Concurrent
Optimization (GCO).  A GCO is able to simultaneously consider the
entire topology of the network and the complete set of existing LSPs,
and their respective constraints, and look to optimize or re-optimize
the entire network to satisfy all constraints for all LSPs.  A GCO
may also be applied to some subset of the LSPs in a network.  The GCO
application is primarily a Network Management System (NMS) solution.

While GCO is applicable to any simultaneous request for multiple LSPs
(for example, a request for end-to-end protection), it is not
invisaged that global concurrent reoptimization would be applied in a
network (such as an MPLS-TE network) that contains a very large
number of very low bandwidth or zero bandwidth LSPs since the large
scope of the problem and the small benefit of concurrent
reoptimization relative to single LSP reoptimization is unlikely to
make the process worthwhile.  Further, applying global concurrent
reoptimization in a network with a high rate of change of LSPs
(churn) is not advised because of the likelihood that LSPs would
change before they could be gloablly reoptimized.  Global
reoptimization is more applicable to stable networks such as
transport networks or those with long-term TE LSP tunnels.

This document provides application-specific requirements and the PCEP
extensions in support of GCO applications.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-pce-global-concurrent-optimization-04.txt

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