[Beowulf] Terrible scaling with a Cisco Catalyst 2948G-GE-TX Switch

[Felix Rauch Valenti]

On Fri, 11 Mar 2005 15:56:26 -0500, Mauricio Carrillo Tripp
<trippm at gmail.com> wrote:
[...]
> I recently got another 32 pc's to build a new cluster, but this time I had to
> buy a more expensive switch (Cisco Catalyst 2948G-GE-TX, ~$3,000). To
> my surprise, the scaling is just TERRIBLE, and after a lot of tests I finally
> found that the problem is the switch (I'm not sure what or why exactly, though).
[...]

I don't know about the 2948G you mention above, but we had some
serious performance problems with a 2900XL about 4 years ago. You can
find my mails from back then in the list archives:

http://www.beowulf.org/archive/2001-August/004688.html
http://www.beowulf.org/archive/2002-May/007161.html
http://www.scyld.com/pipermail/beowulf/2001-May/003763.html

Basically the switch's performance broke down completely as soon as
more than half of its ports where fully loaded with full-duplex
communication.

- Felix