We have seen that using VLANs to segment a switched network provides improved performance, manageability, and security. Trunks are used to carry information from multiple VLANs between devices. However, because these VLANs have segmented the network, a Layer 3 process is required to allow traffic to move from one network segment to another.

This Layer 3 routing process can either be implemented using a router or a Layer 3 switch interface. The use of a Layer 3 device provides a method for controlling the flow of traffic between network segments, including network segments created by VLANs.

This chapter focuses on the methods used for the implementation of inter-VLAN routing. It includes configurations for both the use of a router and a Layer 3 switch. It also describes issues encountered when implementing inter-VLAN routing and standard troubleshooting techniques.