Based on the following show ip bgp neighbor 10.1.1.1 output:
R1#show ip bgp neighbors 10.1.1.1
BGP neighbor is 10.1.1.1, remote AS 65103, external link BGP version 4, remote under ID 0.0.0.0
BGP state = Active
Last read 00:00:04, hold time is 180, keepalive interval is 60 seconds
Received 44 messages, 0 notifications, 0 in queue Sent 45 messages, 6 notifications, 0 in queue
Route refresh request: received 0, sent 0
Default minimum time between advertisement runs in 30 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 0
Index 2, Offset 0, Mask 0x4
0 accepted prefixes consume 0 bytes
Prefix advertised 0, suppressed 0, withdraw 0
Number of NLRIs in the update sent: max 0, min 0 Connections established 7; dropped 7
Last reset 00:05:18, due to BGP Notification received, peer in wrong AS
External BGP neighbor may be up to 2 hops away.
No active TCP connection
What is causing the BGP session to the 10.1.1.1 neighbor to toggle between the Idle and Active state?
A.
There is an AS number configuration error.
B.
The BGP neighbor 10.1.1.1 is not reachable.
C.
The EBGP-multihop value for neighbor 10.1.1.1 is set to the default value.
D.
The BGP session is using the loopback interface but the update source is not set to specify the loopback interface.
Explanation:
The key is looking at the last section of the output. We specified the neighbor in AS 65103 but received an error (Notification) that it is not in that AS.