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

["Wei Gengyu" <[e-mail]>]

Hi, all,

No matter what you want to express,
the explanation of your assumed model is incorrect.

Also, see comments inline.

Gengyu

----- Original Message ----- 
From: "Anna Charny (acharny)" <[e-mail]>
To: "Georgios Karagiannis" <[e-mail]>; 
<[e-mail]>; <[e-mail]>
Cc: <[e-mail]>
Sent: Thursday, March 20, 2008 4:33 AM
Subject: Re: [PCN] Concensus questions from Thursday's PCN meeting


> Hi Georgios,
>

>  Assume now that the link in question has a very high overload.  I would
> assume is 5X overload is quite large (Rudiger I am sure will agree :)),
> so let us just take 5.  That means that approximately 80% of traffic of
> this IEA is dropped at the input, so we end up having only 0.2K actually
> leaving this link.

It is wrong.
You can not get 0.2K ACTUALLY!
And because of this, the following calculation is inredible.


>
> Now assume that the admission threshold is set to 80% of your link
> (picking a high value to make things worse). And assume we are running
> SM - or LC-PCN (or whatever other alg that uses excess marking).  Now
> that means that ~20% of our remaining traffic of the IEA aggregate gets
> marked. The egress now sees:  0.2*0.2K=0.04K of marked traffic and
> (M-1)K+0.2*0.8K unmarked traffic.  The CLE now is now ~0.04K/15K~0.002.
> If you need a larger CLE than that, then neither SM, nor, for that
> matter, LC-PCN, would trigger admission stop on that aggregate (without
> probing added).
>
>
> Anna
>

Strongly suggest people refer to textbook about throughput performance of 
congested node.
The throughput of the congested will be different in case the input is 5*X 
and 16*X.

Gengyu 

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