bgpd - Session Engine Finite State Machine for each neighbor States: None: new, uninitialized neighbor, internal state Idle: no connections accepted, none attempted Connect: trying to open a tcp connection via connect(2) Active: accepting tcp connection from neighbor, not trying to open one OpenSent: tcp connection established, OPEN message sent OpenConfirm: received OPEN message from peer, waiting for first KEEPALIVE Established: fully established BGP session, KEEPALIVEs are exchanged regularily, routes are exchanged