Load Balancing/Failover Question

I agree. The F5 does not re-balance the connections when a previously down server comes back up. Load balancing decision is made once for the life of a connection, and a new decision is only made when new connections are established.

If you think about it, how does the F5 decide when and which connections to kill? Because assuming this is TCP, you will have to kill the connections, and hope that the end software will establish new connections, which will then get load-balanced. There is no way to silently migrate a TCP connection from one server to another (the other server will not have the context needed to transparently continue processing the migrated connection).

If the connections are long-lived (as they seem to be) and have periods of inactivity (idleness), and the clients can reconnect transparently, then you can lower idle timeouts on your TCP profile so that reconnection attempts cause load-balancing to take place. The F5 will TCP RST a connection when the idle timeout is reached, and the client will if designed so, reconnect.

Ultimately, with irules, almost anything is possible, but it will require a pretty clever and complex irule to accomplish this by reading pool member states, and randomly killing some connections if the desired pattern of pool member availability happens (your LB Method will need to be Least Connections)