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

"Georgios Karagiannis" <karagian@cs.utwente.nl> Thu, 20 March 2008 09:46 UTC

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From: Georgios Karagiannis <karagian@cs.utwente.nl>
To: philip.eardley@bt.com, steven.blake@ericsson.com
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Date: Thu, 20 Mar 2008 10:36:21 +0100
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Cc: pcn@ietf.org
Subject: Re: [PCN] Concensus questions from Thursday's PCN meeting
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Hi Phil

Indeed I am refering to SM!

Best regards,
Georgios 

> -----Original Message-----
> From: philip.eardley@bt.com [mailto:philip.eardley@bt.com] 
> Sent: woensdag 19 maart 2008 17:16
> To: karagian@cs.utwente.nl; steven.blake@ericsson.com
> Cc: pcn@ietf.org
> Subject: RE: [PCN] Concensus questions from Thursday's PCN meeting
> 
> Ok - you'd forgotten to remind us of that!
> Note that you're making the assumption of SM [for CL (is 
> excess rate marking just for termination) the requirement is 
> to see one mark.]
> 
> > -----Original Message-----
> > From: Georgios Karagiannis [mailto:karagian@cs.utwente.nl]
> > Sent: 19 March 2008 16:10
> > To: Eardley,PL,Philip,CXR9 R; steven.blake@ericsson.com
> > Cc: pcn@ietf.org
> > Subject: RE: [PCN] Concensus questions from Thursday's PCN meeting
> > 
> > Hi Phil
> > 
> > But in order to trigger the admission control and flow termination, 
> > the situation CLE > 1% has to be first triggered.
> > 
> > Best regards,
> > Georgios
> > 
> > 
> > > -----Original Message-----
> > > From: philip.eardley@bt.com [mailto:philip.eardley@bt.com]
> > > Sent: woensdag 19 maart 2008 17:07
> > > To: karagian@cs.utwente.nl; steven.blake@ericsson.com
> > > Cc: pcn@ietf.org
> > > Subject: 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
> > > > >
> > > >
> > > >
> > > > _______________________________________________
> > > > PCN mailing list
> > > > PCN@ietf.org
> > > > https://www.ietf.org/mailman/listinfo/pcn
> > >
> > 
> 


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