Subject: [Pce] I-D ACTION:draft-ietf-pce-of-01.txt

From: [email-masked]
Date: Mon, 19 Nov 2007 12:15:02 -0500

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		: Encoding of Objective Functions in Path Computation Element communication Protocol (PCEP)
	Author(s)	: J. Le Roux, et al.
	Filename	: draft-ietf-pce-of-01.txt
	Pages		: 17
	Date		: 2007-11-19
	
The computation of one or a series 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(s), referred to as an objective 
   function (e.g. minimum cost path, widest path, etc.). A Path 
   Computation Element (PCE) may support one or multiple objective 
   functions, and it is desired for a Path Computation Client (PCC) to 
   automatically discover the set of objective functions supported by a 
   PCE. Furthermore, it may be useful for a PCC to specify in a path 
   computation request the required objective function to be used by the 
   PCE to compute a TE LSP or a set of TE LSPs. Thus the aim of this 
   document is to define extensions to the PCE communication Protocol 
   (PCEP) in order to allow a PCC to discover the set of objective 
   functions supported by a PCE as well as to allow a PCC to indicate in 
   a path computation request the required objective function and a PCE 
   to indicate in a path computation reply the objective function that 
   was used for path computation.

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From: "LE ROUX Jean-Louis RD-CORE-LAN" <[email-masked]>
Date: Mon, 26 Nov 2007 20:59:40 +0100

Hi all,

Here are the changes in this new revision:

-The discovery of the Objective Functions (OF) supported by a PCE used to rely on the PCED TLV carried in ISIS/OSPF.  Actually for scalability reasons, the OSPF/ISIS PCED TLV has been closed, and no new sub-TLVs can be added, so we can no longer rely on the PCED TLV for OF discovery. 
Following the requirements set forth in RFC 4657 & 4674, and as OF can be considered as a detailed capability, its discovery could rely on PCEP. 
For that purpose we moved OF discovery from ISIS/OSPF to PCEP. A new PCEP TLV has been defined, the OF-List TLV, to be carried within the Open object. This allows discovering the OF supported by a PCE during session setup phase.

-We factorized the transport of the OF in a PCRep for a synchronized computation:
"When the PCE wants to indicate to the PCC the objective function that was used for the synchronized computation of a set of paths, the PCRep message MUST include the corresponding SVEC object directly followed by the OF object, which MUST NOT be repeated for each elementary request."

-Also we made some rewording for the sake of clarity.

Of course your feedback/comments are welcome.

Regards,

J-L, J-P, Young

> -----Message d'origine-----
> De : [email-masked] [mailto:[email-masked]] 
> Envoyé : lundi 19 novembre 2007 18:15
> À : [email-masked]
> Cc : [email-masked]
> Objet : [Pce] I-D ACTION:draft-ietf-pce-of-01.txt 
> 
> A New Internet-Draft is available from the on-line 
> Internet-Drafts directories.
> 	Title		: Encoding of Objective Functions in 
> Path Computation Element communication Protocol (PCEP)
> To remove yourself from the I-D Announcement list, send a 
> message to [email-masked] with the word 
> unsubscribe in the body of the message. 
> Internet-Drafts are also available by anonymous FTP. Login 
> with the username "anonymous" and a password of your e-mail 
> address. After logging in, type "cd internet-drafts" and then 
> http://www.ietf.org/shadow.html or 
> ftp://ftp.ietf.org/ietf/1shadow-sites.txt
> 
> Below is the data which will enable a MIME compliant mail 
> reader implementation to automatically retrieve the ASCII 
> version of the Internet-Draft.
>