iRule to test tcp availability

[root@ve10:Active] config  b virtual bar list
virtual bar {
   snat automap
   pool foo
   destination 172.28.19.252:any
   ip protocol 6
   rules myrule
}
[root@ve10:Active] config  b pool foo list
pool foo {
   members {
      200.200.200.101:any {}
      200.200.200.102:any {}
      200.200.200.111:any {}
      200.200.200.112:any {}
   }
}
[root@ve10:Active] config  b rule myrule list
rule myrule {
   when CLIENT_ACCEPTED {
  set c 1
  log local0. "--"
  log local0. "\[table lookup tbl[TCP::local_port]\] [table lookup tbl[TCP::local_port]]"
  if { [table lookup tbl[TCP::local_port]] ne "" } {
    node [table lookup tbl[TCP::local_port]]
    log local0. "node [table lookup tbl[TCP::local_port]]"
  }
}
when LB_SELECTED {
  log local0. "\[LB::server addr\] [LB::server addr]"
}
when LB_FAILED {
  if { $c < [active_members foo] } {
    LB::reselect pool foo
    log local0. "LB::reselect pool foo"
    incr c
  }
}
when SERVER_CONNECTED {
  table set "tbl[TCP::remote_port]" [IP::remote_addr]
  log local0. "table set \"tbl[TCP::remote_port]\" [IP::remote_addr]"
  log local0. "connection [IP::client_addr]:[TCP::client_port] > [clientside {IP::local_addr}]:[clientside {TCP::local_port}] > [IP::remote_addr]:[TCP::remote_port]"
}
}

 1st request: load balance and save successful pool member

Mar 12 22:17:36 local/tmm info tmm[4950]: Rule myrule : --
Mar 12 22:17:36 local/tmm info tmm[4950]: Rule myrule : [table lookup tbl80]
Mar 12 22:17:36 local/tmm info tmm[4950]: Rule myrule : [LB::server addr] 200.200.200.101
Mar 12 22:17:36 local/tmm info tmm[4950]: Rule myrule : table set "tbl80" 200.200.200.101
Mar 12 22:17:36 local/tmm info tmm[4950]: Rule myrule : connection 172.28.19.251:43695 > 172.28.19.252:80 > 200.200.200.101:80

 2nd request: send request to the pool member previously saved

Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : --
Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : [table lookup tbl80] 200.200.200.101
Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : node 200.200.200.101
Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : [LB::server addr] 200.200.200.101
Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : table set "tbl80" 200.200.200.101
Mar 12 22:17:44 local/tmm info tmm[4950]: Rule myrule : connection 172.28.19.251:43696 > 172.28.19.252:80 > 200.200.200.101:80

 3rd request: if server is changed to another pool member (i.e. 200.200.200.101:80 is no longer availabe), load balance and save new successful pool member

Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : --
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : [table lookup tbl80] 200.200.200.101
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : node 200.200.200.101
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : [LB::server addr] 200.200.200.101
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : LB::reselect pool foo
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : [LB::server addr] 200.200.200.111
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : table set "tbl80" 200.200.200.111
Mar 12 22:18:02 local/tmm info tmm[4950]: Rule myrule : connection 172.28.19.251:43697 > 172.28.19.252:80 > 200.200.200.111:80