Subject: Confusion on spec in MPLS support of Diff-Serv

From: "Thomas Huang" <[email-masked]>
Date: Wed, 20 Sep 2000 10:35:33 -0700

Hello:

I am not clear if the handling of RVSP path message w/o diffserv object in
the draft is workable (section 5.3 : handling diffserv object - by Le
Faucheur)

In Section 5.3, it says when a LSR receives a PATH message without DIFFSERV
OBJECT, it should interpret this a a request for an E-LSP using the
preconfigured EXP-PHB mapping.
But then it adds that for compatibility, an overwrite option can be
activated for LSRs that don't support diff-serv.

It appears to me that these two things are conflicting because a LSR may
support both diff-serv and non-diff-serv, i.e. how does a LSR know a RSVP
path msg without diffserv object should use preconfigured exp-phb or just
behave as a non-diff-serv aware LSR.

Thanks for any clarification and help.

Thomas

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From: Curtis Villamizar <[email-masked]>
Date: Wed, 20 Sep 2000 16:36:35 -0400

> behave as a non-diff-serv aware LSR.

Unsignaled E-LSP behaves the way the user configures it to behave.  If
it is configured to map all EXP to BE it does so.

Curtis

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From: Francois Le Faucheur <[email-masked]>
Date: Thu, 21 Sep 2000 15:29:43 +0200

Thomas,

>behave as a non-diff-serv aware LSR.

The draft states that the "override option" is a configurable thing.

So:
	-  if the "override option" is not supported or has not been turned on by configuration, then the LSR will consider an LSP signaled without a Diff-Serv object as a Diff-Serv E-LSP that will be using the "preconfigured EXP<-->PHB mapping".

	-  if the "override option" is supported and has been turned on by configuration, then the LSR will consider an LSP signaled without a Diff-Serv object as a non-Diff-Serv LSP that will be granted some non-Diff-Serv QoS treatement (for instance Int-Serv Controlled Load or Guaranteed Service).

Does ths clarify?

Francois

>Thanks for any clarification and help.
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Francois Le Faucheur   
Development Engineer, IOS Layer 3 Services 
Cisco Systems 
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