Re: [PCN] Concensus questions from Thursday's PCN meeting

Georgios,

I notice you refer to CLE below. Note that for termination the relevant
parameter is the Sustainable rate, that is the rate of unmarked pkts
(or, if SM being used, this rate is multiplied by the domain-wide
parameter U). 

phil

> -----Original Message-----
> From: pcn-bounces@ietf.org [mailto:pcn-bounces@ietf.org] On Behalf Of
> Georgios Karagiannis
> Sent: 19 March 2008 15:49
> To: 'Steven Blake'
> Cc: pcn@ietf.org
> Subject: Re: [PCN] Concensus questions from Thursday's PCN meeting
> 
> Hi Steven
> 
> Okay, I will have to spend some time on this!
> 
> Best regards,
> Georgios
> 
> 
> > -----Original Message-----
> > From: Steven Blake [mailto:steven.blake@ericsson.com]
> > Sent: woensdag 19 maart 2008 16:43
> > To: Georgios Karagiannis
> > Cc: pcn@ietf.org
> > Subject: RE: [PCN] Concensus questions from Thursday's PCN meeting
> >
> > On Wed, 2008-03-19 at 16:24 +0100, Georgios Karagiannis wrote:
> >
> > > Hi Steven
> > >
> > > Please see that I have included some information into the
> > last bullet:
> > >
> > > - There is an ingress-egress aggregate whose traffic is
> > split across
> > > multiple paths via ECMP.
> > >  - Traffic is admitted along this split path.
> > >  - One (or more) of the paths fails.
> > >  - One (or more) of the remaining paths becomes severely
> > congested (for
> > >    example because there is traffic from other ingress-egress
> > > aggregates flowing along that path).
> > > - <<Due to the ECMP routing not congested paths will
> > forward packets
> > > belonging to
> > >   the same ingress-egress-aggregate that will be unmarked.>>
Marked
> > > packets are
> > >   preferentially dropped at the severely congested
> > >   router(s). As a consequence, not enough marked traffic arrives
at
> > > the egress router to drive the CLE for the ingress-egress
aggregate
> > > above the threshold needed to trigger a response (termination,
say).
> >
> > Ok.  To be specific, the egressrouter  will see some fraction
> > of packets from the severely congested router(s), some of
> > which will be marked, and will see a larger fraction of
> > un-marked packets from the un-pre-congested routers.
> >
> > So let me now ask you this: given N ECMP paths (after a path
> > failure), with one being severely congested and the rest
> > being un-pre-congested, and given a CLE threshold CLE_thresh
> > at the egress router, can you solve for the minimum
> > PCN_lower_threshold value at the severely congested router,
> > where PCN still works (e.g., CLE crosses the threshold), for
> > the two cases where (1) marked packets are preferentially
> > dropped, and (2) marked packets are dropped with equal
> > probability with un-marked packets?
> >
> >
> >
> > Regards,
> >
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> > Steven Blake                <steven.blake@ericsson.com>
> > Ericsson/Redback Networks               +1 919-472-9913
> >
> 
> 
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