Re: Is the advertisement (IGP) of available BW at each pre-emption le vel is a DS-TE- requirement ?

[Francois Le Faucheur <flefauch@cisco.com>]

Choudhury,

At 20:17 09/11/2001 -0500, Jim Boyle wrote:

>On Fri, 9 Nov 2001, Choudhury, Sanjaya wrote:
>
> >
> >       Hi! I have few questions related to the LSP pre-emption in a DS-TE
> >       environment. I will appreciate, your help with these questions.
> >
> >       Q1. If we support pre-emption _across_ different DiffServ classes,
> >       then what is the advantage in advertising available bandwidth for
> > each
> >       class at _each pre-emption level_ ?
>
>There is no agreed upon protocol proposal for DS-TE right now, preemption
>within and across class types is an issue that has been raised on the
>list.  At this point, the requirements document is under a revision which
>should clarify the need (or lack of need) for this, the revision is
>expected in the next week (or so).  Francois or one of his co-authors
>may answer your question more directly, as you are refering to their
>proposal.

Our previous draft discussed the advantages of advertising bw at each 
preemption level for each Class-Type.
This includes :
         - ability to use one given preemption simultaneously by multiple CTs
         - no dependency on consistent configuration of CT/preemption mapping
         - easier migration scenarios

However, after discussing more with some Service Providers, it seems that 
smaller IGP advertisement maybe more important than these above 
benefits.  We are currently working on merging several of the earlier 
proposals into a common one which would advertise a total of 8 bandwidth 
values.

Francois



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Francois Le Faucheur
Development Engineer, IOS Layer 3 Services
Cisco Systems
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Email:                 flefauch@cisco.com
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