[j-nsp] Summarize Global Table

[Pavel Lunin]

Robert, is there any non-production implementation of simple-va, which we
could play with?

The main concern here is, of course, whether a router will
be infinitely installing/withdrawing tons of FIB entries because of
'natural' prefix flaps, how much black-hole/loop this will create in
practice, and how to deal with it. Did anyone perform some research of this?
Any reports exist?