Yes, NetScope does support VLANs. NetScope enables you to monitor and shape VLAN traffic based on the VLAN tag (the optional IEEE 802.1Q tag in the ethernet frame header). Instead of creating a policy based on IP address ranges or ports simply select the VLAN text box and enter the VLAN value. Refer to Policy Manager article category for more information on creating and editing policies.
This enables you to monitor and shape your network traffic based on VLAN tags, which is simpler if your network is already set up to use them.