the destination. All monitor commands can be negated: 3750 (config) #no monitor session 11 source interface Gi1/0/11 - 12 You can remove all local SPAN, all RSPAN, or all SPAN sessions as a group by adding the local, remote, or all keywords: Chapter 19: Catalyst 3750 Features 3750 (config)#no monitor session ? <1-66> SPAN session number Remove all SPAN sessions in the box local Remove Local SPAN sessions in the box remote Remove Remote SPAN sessions in the box You should always remove your SPAN sessions when you no longer need them. SPAN takes up system resources, and there can be confusion if someone plugs a device into the SPAN destination port. RSPAN works the same way that SPAN does, with the exception that the destination interface is on another switch. The switches must be connected with an RSPAN VLAN. To create an RSPAN VLAN, configure a VLAN and add the remote-span command: 3750-1 (config)#vlan 777 3750-1 (config-vlan)# remote-span If you're running VTP, you may not need to create the VLAN, but you will still need to configure it for RSPAN. In either case, the steps are the same. On the source switch, specify the destination as the RSPAN VLAN: 3750-1(config)#monitor session 11 destination remote vlan 777 You can enter a destination VLAN that has not been configured as an RSPAN VLAN, but, alas, it won't work. Now, on the destination switch, configure the same VLAN as an RSPAN VLAN. Once you've done that, configure a monitor session to receive the RSPAN being sent from the source switch: 3750-2 (config)#vlan 777 3750-2 (config-vlan)# remote-span 3750-2 (config)# monitor session 11 source remote vlan 777 There is no requirement for the monitor session numbers to be the same, but as I like to say, simple is good. If you have not configured the source switch to be the RSPAN source, you will get an error: 3750-2 (config) #monitor session 11 source remote vlan 777 % Cannot add RSPAN VLAN as source for SPAN session 11 as it is not a RSPAN Destination session When using RSPAN, don't use an existing trunk for your 