To troubleshoot active state, what condition describes the issue?

• A. The active state means that the IP address in the neighbor statement has been found and a BGP Open packet has been sent, but no response yet; ensure the source IP or network is advertised into the IGP on the neighboring router.
• B. The session is established and routing begins.
• C. The neighbor's AS misconfigured.
• D. The IGP route to the neighbor is down.

Answer: (A)

In this stage of BGP troubleshooting, you’re looking at why the session hasn’t moved beyond the initial connection attempt. The active state means the router has identified the neighbor’s IP and is trying to establish the TCP session, but the remote side hasn’t replied yet. The condition described—having the neighbor IP known and a BGP Open message being sent but no response—points to a reachability issue related to how the local source IP or the connected network is learned by the neighbor. If the source IP used for the BGP session isn’t reachable on the neighbor’s side because the relevant network isn’t advertised in the IGP, the neighbor won’t see the session and won’t respond. So, the fix is to ensure the local source IP (the IP used for the BGP session) is reachable by the neighbor, meaning the interface’s network or the source address is properly advertised in the IGP on the neighboring router. This confirms that the path to the local side is known and packets can be exchanged to complete the TCP handshake.

In contrast, a fully established session would mean the Open message has been exchanged and routing would begin, a misconfigured neighbor AS would typically prevent session establishment altogether, and an IGP route to the neighbor being down would block reachability entirely rather than explaining a stalled Open exchange after the neighbor IP is found.