port span vlan

Mark

Ofcourse you could configure vlan based span and monitor the traffic on dest port or you could do that as port based span as well. hope this link would be of help

Yes and I would consider using VACLs instead which are more scalable than spans. Although also depends what type of hardware/gear you are running. Spanning can be very intensive, and for smaller switches, I would stick to port spanning. Spanning trunks is perhaps the most dangerous for overrunning your hardware/memory.