Re: [Tsvwg] viewgraphs for a talk in tsvwg in Yokohama tomorrow

Sally,
may be I'm a bit confused, and I hope that you can help me.

My concern about HighSpeedTCP is related to the value of the cwnd you take as 
example.
Nowadys, it seems that the maximum wnd used during transmission by real 
systems is about 32* or 64* MSS (don't forget the rwnd that limits the wnd 
value...). And this is because the end-systems must keep track of all the 
transmitted segments that fit into current transmission window, so that in 
case of packet loss they can retransmit the lost segment.

Neglecting all the possible bottlenecks, but just considering the amount of 
memeory required to keep track of the in fligh packets, we have

 83333*1500 bytes ~ 119Megabytes!

On both sender and receiver side... for every TCP connection
Is this realistic?

I personally don't feel as a big problem the fact that it takes too much time 
to reach window as large as 83333. Simply no end system will ever be able to 
exploit 10Gbps speed with RTT 100ms.

Unless we radically change the sliding window protocol that is at the TCP 
root.

Hope this helps.

+-----------------------------------+
| Marco Mellia - Assistant Professor|
| Tel: 39-011-5644173               |
| Politecnico di Torino             |
| Corso Duca degli Abruzzi 24       |
| Torino - 10129 - Italy            |
| http://www1.tlc.polito.it/mellia  |
+-----------------------------------+

> I am giving a talk in tsvwg tomorrow in Yokohama on the two
> drafts on HighSpeed TCP:
>
> HighSpeed TCP for Large Congestion Windows,
> draft-floyd-tcp-highspeed-00.txt
>
> and:
>
> Limited Slow-Start for TCP with Large Congestion Windows,
> draft-floyd-tcp-slowstart-00.txt
>
> The viewgraphs are at:
> http://www.icir.org/floyd/talks/floyd-tsvwg-Jul02.ps
> http://www.icir.org/floyd/talks/floyd-tsvwg-Jul02.pdf
>
> There is also a HighSpeed Web Page at:
> http://www.icir.org/floyd/hstcp.html
>
> ------
>
> If there is time, I might also talk briefly about a somewhat
> more speculative draft:
>
> Quick-Start for TCP and IP,
> draft-amit-quick-start-00.txt
>
> The viewgraphs for this are at the end of the other viewgraph file.
>
> Quick-Start is designed to allow connections to start up more
> quickly than slow-start, after a pass of feedback from all of
> the routers along the path.
>
>
> Thanks,
> - Sally

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