A BGP session is stuck in the "Connect" state. Which of the following is the most likely reason?

A BGP session being "stuck" in the Connect state means the local router has sent a TCP SYN packet to initiate a connection on port 179 but has not received a TCP SYN-ACK response from the remote peer. This indicates a failure in the TCP three-way handshake. The most likely cause is an issue on the remote peer or the path to it. This includes the remote peer not being configured with a matching neighbor statement, its BGP process not running, or a firewall/ACL blocking incoming TCP port 179 traffic.

A. A local misconfiguration (e.g., wrong peer IP) is possible, but issues on the remote side are a more common and direct cause for a lack of TCP response.
C. If BGP were administratively disabled locally, the router would not attempt to initiate a connection and would remain in the Idle state.
D. This is a specific instance of the correct answer (B). While true, option B is more comprehensive as it covers other remote issues like firewalls.

1. Y. Rekhter, T. Li, S. Hares, "RFC 4271: A Border Gateway Protocol 4 (BGP-4)," IETF, January 2006, Section 8.2.2.2, "Connect State". The description implies that the state persists while "waiting for the TCP connection to be completed," pointing to a lack of response from the peer.

2. Nokia, "7750 SR OS Router Configuration Guide," Release 22.10.R1, Part No: 3HE 18149 AAAD TQZZA, 2022, BGP Troubleshooting Section. This documentation typically correlates the Connect state with Layer 3/4 reachability problems, such as incorrect remote configuration, ACLs, or the remote BGP process being inactive.