Scenario:
A Virtual Server is load balancing connections to a pool with 2 pool members. During maintenance window, one of the two pool members is disabled and maintenance is completed followed by the other pool member.
However, as the users make continuous API calls every 5 seconds, the existing TCP connection never bleeds out. Even after waiting for 24 hours, connections still exist on the disabled pool member.
Solution:
By default, F5 makes load balancing decision when the 1st HTTP request within a TCP connection is received. Subsequent HTTP request within the TCP connection are sent to the same pool member as the very 1st HTTP request.
By enabling OneConnect profile with a /32 netmask (255.255.255.255), we were able to force the F5 to make load balancing decision for every HTTP request instead of its default behavior.
The OneConnect profile used along with disabled or forced-offline setting will move the connection from the failed pool member to the active pool member.