I'm a bit of a newb to the world of networking, so please bear with me.

I work in an environment with many separate vlans spanning several
switches (say about a dozen). Today we had an incident where suddenly
traffic was going ballistic on most ports in the network. Doing a
tcpdump on a particular host on this network, you could actually see
unicast traffic that was neither destined to or coming from the host.
Or, to put it another way, it almost looked like the host was on a hub,
where you could see packets travelling between other hosts on the
network to other destinations.

We shut off some ports where some new windows servers were brought up
today. As soon as those ports were taken offline, then tcpdumps on the
other hosts went to normal (i.e. the only traffic you could see were
broadcasts, or unicasts to and from that host).

Can anyone think of a likely explanation for this?

Please let me know if I'm not making sense!

Thanks in advance,

-S