Subject: [Pce] I-D Action:draft-ietf-pce-global-concurrent-optimization-08.txt

From: [email-masked]
Date: Tue, 6 Jan 2009 14:30:01 -0800 (PST)

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 (PCEP) Requirements and Protocol Extensions In Support of Global Concurrent Optimization
	Author(s)       : Y. Lee, et al.
	Filename        : draft-ietf-pce-global-concurrent-optimization-08.txt
	Pages           : 27
	Date            : 2009-01-06

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 TE 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 TE LSPs, and their respective constraints,
and look to optimize or re-optimize the entire network to satisfy all
constraints for all TE LSPs.  A GCO may also be applied to some
subset of the TE 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 TE
LSPs (for example, a request for end-to-end protection), it is not
envisaged 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 TE LSPs since the
large scope of the problem and the small benefit of concurrent
reoptimization relative to single TE LSP reoptimization is unlikely
to make the process worthwhile.  Further, applying global concurrent
reoptimization in a network with a high rate of change of TE LSPs
(churn) is not advised because of the likelihood that TE LSPs would
change before they could be globally 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-08.txt

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