If we configure the branch routers as stub routers they will not receive queries from our HQ routers. This is a very good technique to stop query traffic!
Why do we call it a stub? You have probably seen one before! A tree that is cut off is called a stub…there’s nothing attached to it anymore.
If you look at our branch routers they are like the tree. There are no other routers behind the branch routers and we don’t want to use them as backup paths so why bother querying them? EIGRP stubs are not an “all or nothing” solution. We have different flavors so you can choose to which types of routes the stub router should receive queries or not.
Here are the flavors we have:
- Receive-only: The stub router will not advertise any network.
- Connected: allows the stub router to advertise directly connected networks.
- Static: allows the stub router to advertise static routes (you have to redistribute them).
- Summary: allows the stub router to advertise summary routes.
- Redistribute:allows the stub router to advertise redistributed routes.
The default is connected + summary. If you like you can mix some of the options with the exception of receive-only because it denies all advertisements. Redistribution is the importing and exporting of routing information from one routing protocol to another.
Let’s look at some configuration examples for the different stub types!
To demonstrate the different stub types I will use the following topology: