We have 2 routers(router1 & router2) that are connected to each other in NY city. Also, Router1 is connected to Router3 in Philly and Router2 is connected to Router4 in Boston. We r running BGP on the routers...The router1-router3 path is the primary path and had to be taken down to repair the circuit. So, the traffic is currently going through the router2-router4 path. When the router1-router 3 circuit is back up again, how do we ascertain that the BGP updates are going through it as opposed to the backup path?