We take RIP first because we do not have to do anything specific for load balancing. If there are multiple paths to reach a network destination with the same metric, RIP automatically load balances them. We will be using an interface type known as loopback to achieve this. A loopback is a virtual interface that behaves like a real interface and takes IP addresses.

We'll use the same topology we've been using throughout this chapter, and just add an extra interface. On router R4, we will add a loopback interface by using the following steps: