The Catalyst 4000 Layer 3 Services module supports two external and two internal Layer 3 Gigabit Ethernet interfaces which run IOS software and 32 10/100 Layer 2 ports which are configurable from the supervisor engine. Map all Layer 2 ports on the Catalyst 4000 family switch with VLANs and trunks to the Layer 3 interfaces on the Catalyst 4000 Layer 3 Services module.