I have a 2960 Catalyst and I need to know if when I set the SPAN port if it operates by listening and sending traffic or does it just listen. to traffic. The reason I need to know this is because I am have trouble getting my Websense to work properly through the new Catalyst. We had it cconnected to an old Enterasys with a mirrored port and it worked fine.... Any advise....
Both above posts are correct in their respective way.
It depends on whether you are talking about source port (mirrored port) or destination port (SPAN/port to which sniffer is connected to). It sounds like your concern is about destination SPAN port.
Anyway as stated before the mirrored port by default mirrors tx/rx traffic and destination SPAN port only receives traffic by default. You have the option of chaning the default behavior in both cases.
By default the span destination will only be in listening mode.
If you configure ingress traffic forwarding, the destination port forwards traffic at layer2
More info on 2960 spans at this link
HTH, rate if it does