BGP update-source vs neighbor ip

This is one of those "I’m not really sure what I’m asking" type questions.

FINALLY, I found a decent explanation of the BGP update-source command and its usefulness: Neighbors mightn’t be directly connected, and therefore there can be alternative paths through the AS to the same neighbor, but arriving on a different interface.

The update-source command also lets you name a loopback address as the update-source (as long as the address is routable through the AS); and apparently, this is the way to go; a loopback interface will never go down.

So…and here’s where the not-sure-what-I’m-asking part comes into play…why bother with separate commands here? Why not just set up a loopback address on the routers you want to run BGP and use that address in the neighbor…remote-as command?

Does it make a whole bunch of sense to give an IP address in the neighbor statement, when _all_ of that address’s uses are going to be performed instead by a different, update-source address?

I welcome your answers.

Or your interpretation of what my question is.

I’m tired.

Zzzzzzz

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