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Confusion on spec in MPLS support of Diff-Serv

  • From: Francois Le Faucheur <flefauch@cisco.com>
  • Date: Thu, 21 Sep 2000 15:29:43 +0200
  • Cc: "'mpls@uu.net'" <mpls@UU.NET>

Thomas,

At 10:35 20/09/2000 -0700, Thomas Huang wrote:
>
>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.
>

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.
>
>Thomas
> 
_________________________________________________________________
Francois Le Faucheur   
Development Engineer, IOS Layer 3 Services 
Cisco Systems 
Office Phone:   	+33 4 92 96 75 64
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