Gigabit Switch

Mark Hahn hahn at
Tue Nov 11 13:27:34 EST 2003

> > 1) Is there any benefit to using "managed"
> >    switch rather than the "unmanaged" ones?
> Frequently "managed" switches are a negative.
> An Ethernet switch should "just work".

indeed.  I usually take an Occam's apprach to features, too.
but I was chatting with a big-gbe switch vendor last week,
and thought of a couple of features which could be useful for HPC:

1. suppose you could attach a QOS/TOS tag to small packets, and 
have the switch give them preferential treatment.  for instance,
if there's a congested port with a backlog, let small packets 
"cut" the queue.

2. the vendor claims that multicast is reliable.  I've often pondered
whether multicast would be worth using in clusters, since it's going
to be faster than even a tree-based multicast (as MPICH/LAM do, I think).

3. it would be neat to be able to query performance/load/queueing stats
from the switch on a per-port basis.

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