Detect if node is half-dead with an iRule?

[root@ve1023:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
   set static::response_timeout  5
}

when HTTP_REQUEST {
   log local0. "Received request, beginning response monitor interval. [clock seconds]"
   set monitor_id [\
      after $static::response_timeout {
         LB::detach
         LB::reselect pool foo2
         log local0. "Timeout $static::response_timeout milliseconds elapsed without server response. [clock seconds]"
      }\
   ]
}

when HTTP_RESPONSE {
   log local0. "Received server response."
   if {[info exists monitor_id]} {
      log local0. "Canceling after script with id $monitor_id"
      after cancel $monitor_id
   }
}
}

 curl -i http://172.28.19.79
...no response...

[root@ve1023:Active] config  tail -f /var/log/ltm
Nov 18 09:52:49 local/tmm notice tmm[24220]: 013e0001:5: Tcpdump starting bcast on :::0 from 127.1.1.1:42905
Nov 18 09:52:59 local/tmm info tmm[24220]: Rule myrule : Received request, beginning response monitor interval. 1321638779
Nov 18 09:52:59 local/tmm info tmm[24220]: Rule myrule : Timeout 5 milliseconds elapsed without server response. 1321638779

[root@ve1023:Active] config  tcpdump -nni 0.0 port 80 or port 88
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on 0.0, link-type EN10MB (Ethernet), capture size 108 bytes
09:52:59.853876 IP 172.28.19.253.49633 > 172.28.19.79.80: S 1454416003:1454416003(0) win 5840 
09:52:59.853911 IP 172.28.19.79.80 > 172.28.19.253.49633: S 1517764163:1517764163(0) ack 1454416004 win 4380 
09:52:59.855952 IP 172.28.19.253.49633 > 172.28.19.79.80: . ack 1 win 46 
09:52:59.855977 IP 172.28.19.253.49633 > 172.28.19.79.80: P 1:155(154) ack 1 win 46 
09:52:59.856051 IP 200.200.200.10.49633 > 200.200.200.101.88: S 3113407707:3113407707(0) win 4380 
09:52:59.857029 IP 200.200.200.101.88 > 200.200.200.10.49633: S 1833697333:1833697333(0) ack 3113407708 win 5792 
09:52:59.857038 IP 200.200.200.10.49633 > 200.200.200.101.88: . ack 1 win 4380 
09:52:59.857047 IP 200.200.200.10.49633 > 200.200.200.101.88: P 1:155(154) ack 1 win 4380 
09:52:59.857983 IP 200.200.200.101.88 > 200.200.200.10.49633: . ack 155 win 54 
09:52:59.860978 IP 200.200.200.10.49633 > 200.200.200.101.88: F 155:155(0) ack 1 win 4380 
09:52:59.861895 IP 200.200.200.101.88 > 200.200.200.10.49633: F 1:1(0) ack 156 win 54 
09:52:59.861909 IP 200.200.200.10.49633 > 200.200.200.101.88: . ack 2 win 4380 
09:52:59.955864 IP 172.28.19.79.80 > 172.28.19.253.49633: . ack 155 win 4534