Monitor settings - Interval, Timeout, etc.

Hi Randy, I wondered that a while back and did some testing using nc and telnet while running tcpdump. My tests were run on early 10.x BIG-IP LTM using an HTTP monitor. Note sure which exact version. From my notes:

 

 

The interval takes effect whenever an HTTP health monitor connects to the pool member. This behavior is different if the health monitor passes or fails. For a passing monitor, the succesful GET will close the connection and mark the pool member up. The LTM will then use the interval timer to establish a new connection. For the default interval/timeout 5/16, the health monitor may invoke a new connection and GET around every 5 seconds.

 

 

For a failed monitor, the LTM will establish a connection to the pool member and send up to 4 GET's, per the interval set, before closing the connection. If, after 4 GET's, the timeout has not been met, the LTM will establish a new connection and will continue this behavior until the timeout has been exceeded. At that time the LTM will mark a pool member down.