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

[Giles Heron <giles@packetexchange.net>]

yes, I'd agree with Neil on this.

regardless of the problem we're trying to solve I'm far from sure that
pre-emption is a good answer.  I'd rather know a-priori what LSPs I have
in my network than have a model where LSPs can get bumped off the
network by other LSPs.

Giles

On Mon, 2002-07-15 at 09:47, 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.
> 
> 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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Giles Heron    Principal Network Architect    PacketExchange Ltd.
ph: +44 7880 506185              "if you build it they will yawn"
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