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BGP Neighbor down states

BGP Neighbor down states

Troubleshooting for BGP neighbor down. We can check with  #debug ip bgp events command. 

When the neighbor interface shut down we can see the log like that.

*Mar  1 00:57:57.451: BGP: 10.1.12.2 remote close, state CLOSED
*Mar  1 00:57:57.451: BGP: 10.1.12.2 -reset the session
*Mar  1 00:57:57.451: BGPNSF state: 10.1.12.2 went from nsf_not_active to nsf_not_active
*Mar  1 00:57:57.455: BGP: 10.1.12.2 went from Established to Idle
*Mar  1 00:57:57.455: %BGP-5-ADJCHANGE: neighbor 10.1.12.2 Down Peer closed the session

When neighbor advertise again with wrong AS after established.

*Mar  1 01:03:01.827: BGP: 10.1.12.2 remote close, state CLOSEWAIT
*Mar  1 01:03:01.827: BGP: 10.1.12.2 -reset the session
*Mar  1 01:03:01.827: BGPNSF state: 10.1.12.2 went from nsf_not_active to nsf_not_active
*Mar  1 01:03:01.827: BGP: 10.1.12.2 went from Established to Idle
*Mar  1 01:03:01.827: %BGP-5-ADJCHANGE: neighbor 10.1.12.2 Down Peer closed the session

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