ch. 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 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 RSPAN VLAN. SPAN can create a large amount of traffic. When monitoring VLANs composed of multiple gigabit interfaces, the SPAN traffic can easily overwhelm a single gigabit RSPAN link. Whenever possible, set up a dedicated RSPAN VLAN link between the switches. Voice VLAN Voice VLAN is a feature that allows the 3750 to configure a Cisco IP phone that's connected to the switch. The switch uses CDP to transfer to the phone configura- tion information regarding Class of Service (CoS), and the VLANs to be used for voice and data traffic. By default, this feature is disabled, which results in the phone not receiving configuration instructions from the switch. In this case, the phone will send voice and data over the default VLAN (VLAN 0 on the phone). Chapt