i have experienced in the past that when i take the bgp peer down [ shut ] , sessions are being affected .
when a bgp peer tears down, what happens to a session ?
i know in the bgp rib level it has another path to go to .
because there is only one best path, this means that this path only would be installed to rib-fib and the old one be removed.
and this i suppose - takes time .
my question is - during this time do the packets drop ? what happens to them ?
from the router's point of view, is there a difference between shutting the peer and stopping the advertisements ?
is that where and why cisco nsf/bgp graceful restart got into work ?
here is a scenario :
Cust peers to two different ISP's and advertise the same /24 prefx to both .
would like to move all in and out traffic to a single isp without interruption .
* no they cannot have a more specific prefixes to advertise to the other peer and thus "drying" one of the peers .