Router-on-a-stickis a type of router configuration in which a single physical interface manages traffic between multiple VLANs on a network. The router interface have to be configured to operate as a trunk link and is connected to a switch port (SW1) which will have to be configured in trunk mode. The router receives VLAN tagged traffic on the trunk interface from the nearby switch SW1, and forwards the routed traffic out to VLAN tagged destination using the same interface.
A router has two Fast Ethernet interfaces and needs to connect to four VLANs in the local network. How can you accomplish this task, using the fewest physical interfaces and without decreasing network  performance?
answer: Implement a router-on-a-stick configuration