Re: [conex] Potentially interesting ConEx problem

Mirja Kuehlewind <> Thu, 07 March 2013 21:19 UTC

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From: Mirja Kuehlewind <>
Organization: University of Stuttgart (Germany), IKR
Date: Thu, 07 Mar 2013 22:19:18 +0100
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Subject: Re: [conex] Potentially interesting ConEx problem
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Hi Matt,

> The question I was asking was can ConEx help the content provider know
> which bottleneck prevails?   Bob?

(sorry I'm not Bob but will give it a try anyway)

I don't think ConEx can help here. I believe you assume a scenario where the 
content provider is in most cases the sender. With ConEx information will be 
re-insert form the sender into the network. Thus ECN or loss information thus 
will be sufficient at the sender. 

Anyway as I've been recently looking in loss measurement/estimations methods, 
I actually came over the same question. Here my current ideas:

- The client/receiver might know its access bandwidth and could provide this 
information to the server (in a higher layer protocol) or send some 
measurement traffic to the server or a measurement server

- distinguish self-congestion (only one flow on bottleneck link) form shared 
congestion by looking at the lost pattern, e.g. a flow using cubic or reno 
has a very regular loss burst with a defined number of losses in a defined 
period (I'm currently looking at this) if there is no cross traffic 
disturbing the flow

- correlate the losses (or loss pattern) of multiple flows (from the same 
server to different clients) to see if losses occur at the same time/in the 
same period (see network tomography in literature)

Does this help?