nanog mailing list archives

Re: "Does TCP Need an Overhaul?" (internetevolution, via slashdot)


From: Sam Stickland <sam_mailinglists () spacething org>
Date: Mon, 07 Apr 2008 11:29:05 +0100


Kevin Day wrote:
Yeah, I guess the point I was trying to make is that once you throw SACK into the equation you lose the assumption that if you drop TCP packets, TCP slows down. Before New Reno, fast-retransmit and SACK this was true and very easy to model. Now you can drop a considerable number of packets and TCP doesn't slow down very much, if at all. If you're worried about data that your clients are downloading you're either throwing away data from the server (which is wasting bandwidth getting all the way to you) or throwing away your clients' ACKs. Lost ACKs do almost nothing to slow down TCP unless you've thrown them *all* away.
If this was true surely it would mean that drop models such WRED/RED are becoming useless?

Sam


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