Configuring router-on-a-stick inter-VLAN routing

This section describes how to configure router-on-a-stick inter-VLAN routing on a Cisco switch.

Scenario – Router with a single interface

Unlike legacy inter-VLAN routing, the router-on-a-stick option (see Figure 4.8) of the inter-VLAN routing concept uses a different approach to enable communication among VLANs. In this scenario, the router establishes a trunk link with the switch where the VLANs are configured. Then, on the router side, the subinterfaces are configured with the appropriate IP addresses in a way that each subinterface represents a separate subnet, maps a specific VLAN, and tags the frame for the VLANs. In addition, assigning the IP addresses in a PC's interface as per the corresponding subnets of the subinterfaces,the router can then perform communication among VLANs by traversing the trunk link:

Figure 4.8. Router-in-a-stick inter-VLAN routing

The following represents the configurations on a switch, and displaying VLAN information...