A BGP session moves through states as it establishes. Understanding states helps troubleshooting.
The states:
Idle. Initial state. Waiting to start.
Connect. Trying TCP connection to peer.
Active. TCP failed, retrying. (Confusingly named since it means trouble.)
OpenSent. TCP connected, sent OPEN, waiting for peer's OPEN.
OpenConfirm. Received peer's OPEN, sent KEEPALIVE, waiting for peer's KEEPALIVE.
Established. Session up. Exchanging routes.
Stuck in Active? Usually means TCP can't connect. Check IP reachability, firewall rules, and that both sides are configured.