Although VLAN is used to split the broadcast domain, it is necessary to enable communication between two or more VLANs at layer 3 using IP routing. This is called InterVLAN routing and can be configured using both routers and layer 3 switches. This requires allocating a different IP subnet for devices in each VLAN.

We will configure InterVLAN routing by connecting the router to a switch using a single link. All the traffic to other VLANs passes through this link, to the router and back again through this link. This method of configuration is also called router-on-a-stick, as a single link to the router handles all traffic.

InterVLAN on a router

We will use the following topology for this setup:

As stated earlier, each VLAN will have IP addresses from different network ranges and the router's interface will have three IP addresses—each belonging to a different network.

1. After IP addresses have been assigned to all PCs, create the necessary VLANs...