[Beowulf] local and private net on one switch?

[David Mathog]

So I was tracing cables today in a rack I just started managing and
realized  that the rat's nest held quite a surprise - the networks for
both the local and private nets were plugged into the same (dumb)
switch.  That is, both 192.168 and 131.215 packets are bouncing around
inside the same switch.  There is a single cable from the switch to the
campus net (131.215).  I've never heard of mixing nets like that on a
switch, but it seems to be working more or less ok.  Presumably the
machines are seeing martian packets from broadcasts from the other net,
but since not one of them had a firewall running (does this surprise
you?) nothing was logging those events.  

My question is, aside from the obvious security issues, is that sort of
configuration "legal"?  It had been running that way for quite a while,
with no obvious problems resulting.

And yes, I will be separating the two nets as soon as possible.

Thanks,

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