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<DIV><FONT face=Arial size=2>Hi,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I've put a linux patch at <A
href="http://www.hamilton.ie/net">www.hamilton.ie/net</A> that might be of
interest to those working on tcp for high-speed networks. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>One of the issues that has become pretty clear from
initial tests of new tcp congestion control algorithms in high-speed regimes is
that the standard linux tcp stack often performs poorly due to
implementation problems. This was one of the main themes at the recent
PFLDnet workshop at Argonne. Sack processing is very inefficient, leading
to frequent timeouts, the burst moderation implementation often does more harm
than good and packet reordering etc (which seems to be quite common on real
networks) degrades throughput. I've tried to document some of these
problems in the report at <A
href="http://www.hamilton.ie/net/LinuxHighSpeed.pdf">http://www.hamilton.ie/net/LinuxHighSpeed.pdf</A>.
The problems are sufiiciently serious that they frequently obstruct comparisons
and evaluation of proposed tcp congestion control algorithms. The patch at
<A
href="http://www.hamilton.ie/net/2.4.23.HSv4.patch.gz">http://www.hamilton.ie/net/2.4.23.HSv4.patch.gz</A> tries
to address these problems, and seems to work fairly well in the tests I've
carried out on a variety of machines and network paths. Its still very
much experimental code, however, and comments would be appreciated. The
code is a patch against linux 2.4.23 and includes web100 (with implementations
of scalable cp and high-speed tcp) and also an implementation of
htcp.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Doug</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Hamilton Institute</FONT></DIV>
<DIV><FONT face=Arial size=2><A
href="http://www.hamilton.ie">www.hamilton.ie</A></FONT></DIV></BODY></HTML>