Can health monitor maintain TCP connection?

I haven't been in the load balancing business very long, so I'm just guessing here, but it sounds like a passive monitor could be used to watch regular traffic going back and forth between clients and servers, and decide based on some indication from the server when to mark it as overloaded or whatever. I think the 'in conjunction' must come into play because if you were to mark a member of the pool as down, clients can't reach it, so there are no responses to check to mark it as up again, and it would be down forever. If you run the passive monitor on some traffic that is being generated as part of one of the regular health checks, there would be the possibility that the server would start responding correctly and would be enabled for regular traffic.

I did set this up to answer the question "so there are no responses to check to mark it as up again" and have found that the response to the client is the object parsed by the iRule (not the monitor traffic) and the pool member becomes down. Then the monitor comes around and marks it back up until another client request is parsed and marks the member down again. Note: I set the iRule to trigger on 200 OK to make this easier. Client connection results: HTTP/1.1 200 OK Date: Tue, 10 Feb 2015 22:00:48 GMT Server: Apache/2.2.22 (Ubuntu) MISS MISS HTTP/1.1 200 OK Date: Tue, 10 Feb 2015 22:00:48 GMT Server: Apache/2.2.22 (Ubuntu) MISS MISS ------------------------------------------------------------------ What is logged to /var/log/ltm: notice mcpd[6987]: 01071681:5: SNMP_TRAP: Virtual /Common/me2 has become available err tmm[10521]: 01010221:3: Pool /Common/test1 now has available members err tmm[10521]: 01010028:3: No members available for pool /Common/test1 notice mcpd[6987]: 01070638:5: Pool /Common/test1 member /Common/10.12.23.27:80 monitor status iRule down. [ /Common/gateway_icmp: up ] [ was up for 0hr:0min:0sec ] notice mcpd[6987]: 01071682:5: SNMP_TRAP: Virtual /Common/me2 has become unavailable notice mcpd[6987]: 01070727:5: Pool /Common/test1 member /Common/10.12.23.27:80 monitor status up. [ /Common/gateway_icmp: up ] [ was iRule down for 0hr:0min:1sec ] notice mcpd[6987]: 01071681:5: SNMP_TRAP: Virtual /Common/me2 has become available err tmm[10521]: 01010221:3: Pool /Common/test1 now has available members err tmm[10521]: 01010028:3: No members available for pool /Common/test1 notice mcpd[6987]: 01070638:5: Pool /Common/test1 member /Common/10.12.23.27:80 monitor status iRule down. [ /Common/gateway_icmp: up ] [ was up for 0hr:0min:0sec ] notice mcpd[6987]: 01071682:5: SNMP_TRAP: Virtual /Common/me2 has become unavailable notice mcpd[6987]: 01070727:5: Pool /Common/test1 member /Common/10.12.23.27:80 monitor status up. [ /Common/gateway_icmp: up ] [ was iRule down for 0hr:0min:1sec ]