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<TITLE>RE: [e2e] TCP Loss Differentiation</TITLE>
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<P><FONT SIZE=2>Fred,<BR>
<BR>
Actually, it should be possible to combine existing per-flow<BR>
statistics (e.g. Netflow) with the kind of existing radio-aware<BR>
statistics generated by e.g. RFC4938 (also implemented by Cisco),<BR>
to give a good idea of when loss on a (noisy radio) channel is<BR>
correlated to packet loss, and isn't congestion.<BR>
<BR>
A complete history isn't needed. The last couple of hundred<BR>
ms should do it. All that's being done is combining observations<BR>
about the channel, and about the packets flowing through the link,<BR>
available in existing code.<BR>
<BR>
L.<BR>
<BR>
<<A HREF="http://www.ee.surrey.ac.uk/Personal/L.Wood/">http://www.ee.surrey.ac.uk/Personal/L.Wood/</A>><L.Wood@surrey.ac.uk><BR>
<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: end2end-interest-bounces@postel.org on behalf of Fred Baker<BR>
Sent: Mon 2009-02-23 23:10<BR>
To: Jon Crowcroft<BR>
Cc: end2end-interest list<BR>
Subject: Re: [e2e] TCP Loss Differentiation<BR>
<BR>
<BR>
On Feb 23, 2009, at 3:01 PM, Jon Crowcroft wrote:<BR>
<BR>
> if each router were to record in every packet in a flow, all the <BR>
> packets it had seen, the order it had seen them, and the routers own <BR>
> address, then when any packet arrives, you'd have a cmplete history <BR>
> of packets predeceessors and successors and gaps, and where gaps are <BR>
> caused, and so a receiver can disambiguate on a _per packet_ base <BR>
> when a loss was not congestive...<BR>
<BR>
Great! I'm really excited to hear that every router has now sprouted a <BR>
reason to add a few more gigahunks of memory, and that service <BR>
providers are willing to pay the operational expense in heat and <BR>
power! My product managers will be truly dumbfounded that they had not <BR>
tumbled on that source of revenue in the past. And I'm sure that the <BR>
ISPs will be all too eager to pass the upgrade cost along to their <BR>
customers.<BR>
<BR>
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