We have 2 external routers, OSPF on the inside and BGP on the outside.
We had some cabling people knock out our primary router cable at 7:45 one morning, and it didn't cut over to the secondary router, after 15 minutes the problem was identified and the circuit restored.
I have tested the fail over by disconnecting the cable, after 10 minutes it still hadn't failed over so I logged onto the secondary router to check it out. I pinged the next hop, and then the link came up (I'm not sure if it was coincidence as I didn't check the link for another minute, it may not have been instantaneous).
I plugged the cable in and rebooted the second router to restore the route to the primary and tried it all again, this time it cut over after 3 minutes.
Did the ping kick it into life, why would this be the case?