NTP Health CHECK

[root@ve1023:Active] config  b monitor ntp_mon list
monitor ntp_mon {
   defaults from external
   run "ntp_mon.pl"
}

[root@ve1023:Active] config  ls -l /config/monitors/
total 19
-rwxr-xr-x 1 root root 3006 Sep 30 00:33 arg_example
lrwxrwxrwx 1 root root   19 Sep 30 01:01 builtins -> /usr/share/monitors
drwxr-xr-x 3 root root 1024 Feb  9 02:43 CPAN
-rwxr-xr-x 1 root root 3145 Feb  9 04:16 ntp_mon.pl
-rwxr-xr-x 1 root root 1454 Sep 30 00:33 sample_monitor
-rwxr-xr-x 1 root root 2252 Nov 14 22:59 testmonitor.sh

in ntp_mon.pl, i added the $node line since it is noted in external monitor wiki.

my $node = $ENV{"NODE_IP"};
$node =~ s/::ffff://;
my $port = $ENV{"NODE_PORT"};

External Monitor wiki
http://devcentral.f5.com/wiki/AdvDesignConfig.ExternalMonitor.ashx

also, i modified condition to mark pool member down if its stratum is 11.

if ($response{'Stratum'} =~ /\d+/) {
    if the stratum is a number
   if ($response{'Stratum'} == 11) {
      return 0;
   } else {
       and it isn't 11
      return 1;
   }
} else {
   return 0;
}

i set up 3 pool members. ntpd is running on 192.168.11.168 and 200.200.200.101 only. anyway, 200.200.200.101 stratum is 10. so, 200.200.200.101 and 200.200.200.102 will be marked down by the monitor.

[root@ve1023:Active] config  b pool ntp_pool list
pool ntp_pool {
   monitor all ntp_mon
   members {
      192.168.11.168:123 {}
      200.200.200.101:123 {}
      200.200.200.102:123 {}
   }
}

[root@ve1023:Active] config  b pool ntp_pool|grep -i pool\ member
+-> POOL MEMBER ntp_pool/192.168.11.168:123   active,up
+-> POOL MEMBER ntp_pool/200.200.200.101:123   inactive,down
+-> POOL MEMBER ntp_pool/200.200.200.102:123   inactive,down