The SPAN reflector feature enables multicast traffic as well as other traffic that requires central rewrite engine to be switched when it comes from the Firewall Service Module (FWSM). For example, for each FWSM in a switch, the SPAN reflector feature is enabled. This feature uses one SPAN session.
In order to enable the SPAN reflector feature, use the monitor session servicemodulecommand and in order to disable or delete a session, use the no form of this command
Note: If you have a fabric enabled Supervisor card and you disable the span you will loose all multicast, GRE, and Distributed Etherchannel traffic that is transiting the FWSM. Thus it is recommended that you do not disable the span reflector.