[Beowulf] layer 3 switches

Mark Hahn hahn at physics.mcmaster.ca
Thu Sep 21 12:13:42 PDT 2006

> Does a layer 3 switch make sense on a Beowulf cluster running on GigE? If so,
> does anyone have any recommendations?

what's wrong with layer2?  do you have specific L3 (IP-addr-based) things
you want to do with the net?

I can't see any reason, except that managed switches can be quite handy,
and they usually come with a bunch of L>2 goop.

I guess if you're worried about MPI and NFS traffic interfering,
QOS and/or VLANS might be useful.  but frankly, why worry about 
MPI latency if you're using Gb?  or why not just double up,
since you probably already have dual ports on every box and Gb 
switches are dirt cheap (at least <=50 pt ones, and if you're 
going past 50 pt, you probably don't care about both file and MPI
traffic being full-bisection...)

I've had pleasant experiences with commodity-level switches (2848, etc)
from HP, though for various reasons, price wasn't factored into this.
then again, I can't complain about the 3com, dlink, netgear switches
I've used either.  cisco does tend to be expensive...

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