Bgp peer down reason including:
1: Configuration lead peer down(1)
2: Receive notification(2)
3: Receive error packet(3)
4: Hold timer expire(4)
5: Remote peer not reachable(5)
6: Direct connect-interface down(6)
7: Route limit(7)
8: Peer is not up for a specified long time(8)
100: Alarm clear(100)