The moment I wrote “RIP summary routes are not present in the IP routing table” in the RIP Route Database article in the CT3 wiki, I knew it was a recipe for disaster. It’s OK not to advertise what you use (we call this route filters); advertising something you don’t use yourself is slightly stupid.
It didn’t take me long (after I found a few minutes of spare time) to come up with a scenario where RIP interface summary creates a nice routing loop.
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