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RE: IETF54- Informal discussion on BC Model for DS-TE

Neil and all,

At 10:47 15/07/2002 +0100, neil.2.harrison@bt.com wrote:

I'd agree with this too......our experience of pre-emption schemes in other
technologies tells us we would want to be able to disable them.
So we're hearing:
-i- it should be possible to disable preemption
-ii- when preemption is disabled, the Model should still work reasonably well.
Fair enough.

I also understand that:
-iii- there should be effective use of bandwidth (ie good bandwidth sharing among CTs).
-iv- there should be some isolation (ie a CT cannot hogg the bw of another CT).
-v- there should be protection against QoS degradation (at least of the premium CTs e.g Voice, Premium DAta...).
-vi- the BC model should be reasoanly simple and shouldn't require additional IGP extensions.
Is this right, or are any of those actually non-goals?

Thanks

Francois



regards, Neil

> -----Original Message-----
> From: Geib, Ruediger [mailto:Ruediger.Geib@t-systems.com]
> Sent: 15 July 2002 08:21
> To: gash@att.com
> Cc: te-wg@ops.ietf.org
> Subject: RE: IETF54- Informal discussion on BC Model for DS-TE
>
>
> Hi Jerry
>
> > > Russian Dolls model does not "mandate" the use of
> > > preemption. It just uses it for what it has been specified
> > > for (ie bounce off LSPs when needed).
> > >
> > > My impression is that it is just not possible to simultanesouly :
> > >          -(i) ensure bandwidth sharing (ie no bandwidth wastage)
> > >          -(ii) ensure bandwidth isolation (ie a CT cannot
> > >               have some of its bandwidth taken by another CT)
> > >          -(iii) refuse to use preemption
> > >
> > > I believe SPs have requirements for (i) and (ii) and don't
> > > have a problem with using preemption, which is an existing
> > > TE mechanism.
>
> > Not all SPs assume the use of preemption.  So the default BC
> > model should not assume ('require') the use of preemption to
> > operate efficiently.
>
> Yes, that's correct. I'd prefer a default BC model where
> preemption is an optional add on instead of a mandatory feature.
>
> Regards, Rüdiger
>
>
>

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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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