Overview

A switch with multiple VLANs requires a means of passing Layer 3 traffic between those VLANs. This module describes both the process and various methods of routing traffic from VLAN to VLAN. A router that is external to the Layer 2 switch hosting the VLANs can provide the Inter-VLAN routing. When routing occurs within a Catalyst Multilayer Switch, Cisco Express Forwarding (CEF) is deployed to facilitate Layer 3 switching through hardware-based tables providing an optimal packet forwarding process. When implementing CEF, routing is enabled between VLANs through the configuration of Switched Virtual Interfaces associated with the various VLANs on the multilayer switch.