The configuration of multiple Layer 2 VLANs requires that Layer 3 routing
occur between those VLANs. This inter-VLAN routing can be provided external to
a Layer 2 switch or within a Multilayer Switch through the configuration of
Switch Virtual Interfaces and IP routing. When routing occurs within a Catalyst
Multilayer Switch, Cisco Express Forwarding is deployed to facilitate Layer 3
switching through hardware-based tables providing an optimal packet forwarding
process.