OSPF LSA Types Explained

Hello Sims

Hmm, I’m not quite sure what you’re asking, but I’ll do my best to share with you how LSAs work when you have a stub network.

In OSPF, a stub network is defined as a network with only a single connection to other networks. It means that the network only has one way in and one way out.

When Type 1 LSAs are stored within an OSPF router, they contain information about the connection to each of their OSPF neighbors. Within this information is found the type of link, and one of those types of links is the stub type. You can see that in the first table of the lesson.

If we take a look at a Wireshark capture of an OSPF update, we can see this information clearly. The following shows packet number 12 of this particular capture:

Notice that this OSPF update contains many different LSA types, one of which is an LSA Type 1. This type is expanded, and we can see the type of link that this particular LSA indicates, which is a stub. (See highlighted indicators). Does that make sense?

I hope this has been helpful!