
bgpd - Session Engine


Several Timers per neighbor:
IdleHoldTimer
A START event is generated when it expires. A session in Idle state transforms to Connect on expiration. Conditionally started when a session transforms to Idle state, depending on the cause of the session going back to Idle.
ConnectRetryTimer
Sessions in Active state transform to Connect and retry to open a tcp session on expiration. Started when a session transforms from Connect to Active.
HoldTimer
Started when a sessions reaches the Established state, and restarted on reception of a KEEPALIVE packet. When the HoldTimer expires, the session is assumed dead and is reset to Idle state.
KeepAliveTimer
Every time the KeepaliveTimer expires, a KEEPALIVE message is sent and the timer is restarted. Its start value is usually 1/3 of the HoldTime.

