The Catalyst 4003 and 4006 Layer 3 Services module is a 32-port Layer 2 10/100 Ethernet module with a 4-port Gigabit Ethernet Layer 3 uplink module. The Catalyst 4003 and 4006 Layer 3 Services module provides interVLAN routing for the Catalyst 4000 family switch and provides Layer 3 switching between the Gigabit Ethernet interfaces.The Catalyst 4003 and 4006 Layer 3 Services module occupies a single slot in the chassis and has two internal full-duplex Gigabit Ethernet interfaces that connect directly to the Catalyst 4000 family switch backplane to provide routing capability. The 32 10/100 Ethernet interfaces are controlled by the Catalyst 4000 switch supervisor engine. The two external and two internal Gigabit Ethernet interfaces are configured from the Layer 3 services module console. To configure the Layer 3 services module for interVLAN routing, you also must configure the internal Layer 2 Gigabit Ethernet interfaces from the supervisor engine console. You can group the two internal Gigabit Ethernet interfaces into a single Gigabit EtherChannel or configure them as independent interfaces (links). If channeled, the internal Gigabit Ethernet channel supports trunking using the IEEE 802.1Q protocol. You also can configure each Gigabit Ethernet interface (link) independently as a separate VLAN trunk or nontrunked routed interface.