From http://www.unix.com/shell-programming-and-scripting/240459-script-start-services-based-dependent-services-other-aix-machine.html

Dependent script start.sh

while true
do
   if nc -w 2 server2 9999 < /dev/null > /dev/null 2>&1
   then
       # Service is currently running
       [ "$PREV" = "NOT" ]  && /path/to/your/script
       PREV="RUNNING"
  else
      # Service 2 is not running on server2
      PREV="NOT" 
  fi
done