[Beowulf] which 24 port unmanaged GigE switch?

[David Mathog]

Bruno Coutinho  wrote:
> 2010/4/5 David Mathog <mathog at caltech.edu>
> >
> > OK, Netgear is officially scratched off the list.
> > Two votes for HP.
> > Anybody have experience with a D-Link GigE switch?
> >
> 
> 
> The D-link DGS-1024D and DGS-1224T behave like Netgears.
> Once you have many links at near full speed they start to drop packets.
> 
> D-link DGS-3100-24 handles large all to all traffic reasonably well,
but has
> some fans that seem to be very weak.

Dropping packets is one thing (D-Link), dropping dead and needing to be
rebooted (Netgear) is another.  In the case of the reported Netgear
problems it sounds a lot like under heavy load these may be overheating
and crashing.  The D-link issue you describe sounds more like a real
performance problem, as if it cannot actually deliver the claimed
forwarding capacity.

What's bothering me though is that both D-link and Netgear claim the
same top forwarding rate as the more expensive switches, at 48 Gbps. 
Giving them the benefit of the doubt, that they are not intentionally
misrepresenting the speed of these units, perhaps there is some other
variable in play which degrades their performance more than the other
switches?  For instance, cable quality.  Were you using cat 5, cat 5e,
or cat 6 on the D-links that dropped packets under heavy load?  Perhaps
with lower speed patch cables the less expensive switches cannot meet
their published specs?

This is another one of those cases where having a benchmark would be
enormously helpful.  Since reviews for these devices are hardly ever
published, it would at least be nice if end users had a simple way to
compare the performance they observe with different devices.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech