The way i read the article is that the f5 is setup as a ntp client to sync its time. Not sure if the firewall will be open to allow udp 123 incoming to a self-ip address or vip. And if you can setup a vip, you'll some how need to point the pool at itself for time time. Must admit not to sure how to do this. My implementions of NTP have been on simple linux servers 3-4 in a suitable location so they are secure and auditable by the security team for the log auditing policies. Have you got any way to sping up 3-4 small linux boxes and use those instead?