[c-nsp] Best Practices for quickly removing routes when BGP peer drops

[Gert Doering]

Hi,

On Wed, Dec 10, 2025 at 07:12:25PM +0100, Lukas Tribus via cisco-nsp wrote:
> I don't understand.
> 
> How is this supposed to work without transient loops and without
> tunneling (label unicast/vpnv4), when your core has yet to converge?
> 
> For this to work the internal routers you cross all would have to
> converge their FIB at the same time at the same speed and in the same
> order?
> 
> What am I missing here?

Without labels ("any sort of tunnels") you would see transient loops,
but convergence would still be faster if the edge already has a candidate
backup path - as compared to "send withdraw, wait for the other side(s)
to process the withdraw, and send the new-best path back".  So it will
be converged after "process withdraw, select new path".

gert
-- 
"If was one thing all people took for granted, was conviction that if you 
 feed honest figures into a computer, honest figures come out. Never doubted 
 it myself till I met a computer with a sense of humor."
                             Robert A. Heinlein, The Moon is a Harsh Mistress

Gert Doering - Munich, Germany                             gert at greenie.muc.de
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