OSPF and loopback interfaces

You have seen that I have configured a loopback address in the previous lab, so let me explain to you why we really use them. We can use them for a variety of reasons. Laziness is one reason. I don't want to create a LAN, so I use loopback interfaces instead. They can be used for real purposes, such as diagnostics. You can always source a loopback address. Also, you would have an interface that never goes down, because it is virtual.

Most importantly, they are used in the election process of the designated router and back-up designated router, but we will get to that in a little bit. So, loopback interfaces can help us a lot and configuring them is very simple.

This is how you would configure a loopback address: ...

Get CCNA Routing and Switching 200-125 Certification Guide now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.