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

"Georgios Karagiannis" <karagian@cs.utwente.nl> Wed, 26 March 2008 09:52 UTC

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From: Georgios Karagiannis <karagian@cs.utwente.nl>
To: 'Steven Blake' <steven.blake@ericsson.com>
References: <1B6169C658325341A3B8066E23919E1CF64CFA@S4DE8PSAANK.mitte.t-com.de><75A199C5D243C741BF3D3F1EBCEF9BA503B34667@E03MVZ1-UKDY.domain1.systemhost.net><004e01c889d1$6d01e4f0$810c5982@dynamic.ewi.utwente.nl><1205939802.3021.9.camel@neutrino><005501c889d5$5acccdf0$810c5982@dynamic.ewi.utwente.nl><1205941357.3021.18.camel@neutrino><000401c88ab4$35903a10$810c5982@dynamic.ewi.utwente.nl><1206458384.3065.24.camel@neutrino> <000301c88f1f$ccd972a0$810c5982@dynamic.ewi.utwente.nl>
Date: Wed, 26 Mar 2008 10:49:37 +0100
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Cc: pcn@ietf.org
Subject: Re: [PCN] Concensus questions from Thursday's PCN meeting
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Hi Steven

The comments that I have sent in the previous email cannot be clearly seen.
Please see again in line:

 

> -----Original Message-----
> From: pcn-bounces@ietf.org [mailto:pcn-bounces@ietf.org] On 
> Behalf Of Georgios Karagiannis
> Sent: woensdag 26 maart 2008 10:00
> To: 'Steven Blake'
> Cc: pcn@ietf.org
> Subject: Re: [PCN] Concensus questions from Thursday's PCN meeting
> 
> Hi Steven
> 
> Please see in line!
>  
> 
> > -----Original Message-----
> > From: Steven Blake [mailto:steven.blake@ericsson.com]
> > Sent: dinsdag 25 maart 2008 16:20
> > To: Georgios Karagiannis
> > Cc: pcn@ietf.org
> > Subject: RE: [PCN] Concensus questions from Thursday's PCN meeting
> > 
> > On Thu, 2008-03-20 at 18:59 +0100, Georgios Karagiannis wrote:
> > 
> > [snip]
> > 
> > > When router is preferentially dropping marked packets:
> > > 
> > > PCN_lower_threshold (1) < C1*(99%) - 1%* (C2 + C3 + C4 + C5)
> > > 
> > > 
> > > 
> > > 
> > > -----------------------------------------------------
> > > 
> > > When router is dropping marked and unmarked packets are 
> with equal 
> > > probability p:
> > > 
> > > 
> > > PCN_lower_threshold (2) < MINIMUM {C1; SECOND_PART}, where:
> > > 
> > >                 [(C1 + C6) - 1%C1 - 1%(C2 + C3 + C4 + C5)]}
> > >  SECOND_PART=                 ----------------------------
> > >                                     50%
> > > 
> > > PCN_lower_threshold (2) < MINIMUM {C1; SECOND_PART}, where:
> > > 
> > >               [(2*C1) - 1%C1 - 1%(C2 + C3 + C4 + C5)]}
> > > SECOND_PART =            --------------------------------
> > >                             50%
> > > 
> > > => PCN_lower_threshold (2) < C1
> > > 
> > > 
> > > Therefore, the second scheme (2) can be considered more 
> robust and 
> > > more stable then the first scheme.
> > 
> > Georgios,
> > 
> > If I assume that C1 = C2 = C3 = C4 = C5, then
> > 
> > PCN_lower_threshold(1) < (0.99 * C1) - (0.01 * 4 * C1) = 0.95 * C1
> > 
> > whereas
> > 
> > PCN_lower_threshold(2) < C1
> > 
> > I think you will agree that this is not a significant difference.
> 

Georgios: For this example, yes, but note that not all links 
in the PCN domain will support equal bandwidth!
Consider that the following situation occurs:
 
 C2=C3=C4=C5= 10*C1
 Thenn (1) will be:
 
PCN_lower_threshold(1) < (0.99 * C1) - (0.01 * 4 * 10 *C1) 

 PCN_lower_thhershold (1) < C1 (0.99 - 0.4) 

 PCN_lower_thhershold (1) < C1 * 0.59


 Whereas:
 
 PCN_lower_threshold (2) < C1
 
 Best regards,
 Georgios
> 
> 
> 
> 
> 
> > 
> > 
> > Regards,
> > 
> > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> > Steven Blake                <steven.blake@ericsson.com>
> > Ericsson/Redback Networks               +1 919-472-9913
> > 
> 
> 
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