LTM's external monitors are incredibly flexible, fairly easy to implement, and especially useful for monitoring applications for which there is no built-in monitor template. They give you the ability...
Just to add one more thing to the below advice - as long as your monitor node supports IPv6, you can modify the script to REMOVE the route domain from the IP string that the F5 passes to your script, by replacing the:
IP=`echo ${1} | sed 's/::ffff://'
with
IP=`echo ${1} | sed 's/%100//' (or whatever your route domain is...)
Then follow the suggestion below and the square brackets around the IP variable, and add the g to the curl command.