Hi,
Simple persistence is now known as source address persistence or source address affinity. Using source address persistence, requests from the same client IP address (or subnet) are persisted to the same server.
If LTM marks a pool member down, the pool's setting for 'action on service down' is used. You can check the online help for details for the option:
Action on Service Down
Specifies how the system should respond when the target pool member becomes unavailable. The default is None.
* None: Specifies that the system does not select a different node. Selecting None causes the system to send traffic to the node even if it is down, until the next health check is done.
* Reject: Specifies that the system sends an RST or ICMP message.
* Drop: Specifies that the system simply cleans up the connection.
* Reselect: Specifies that the system selects a different node. Selecting Reselect causes the system to send traffic to a different node after receiving the message that the original node is down.
Aaron