NTP: BigIP LB Upable to sync

Clock differences may be a cuplrit in this case. Certainly there may be other possibilities for the sync problem. Sometimes we have been able to sort out with reconfiguring the ha.

As you can see from the ntpq -np command there is a failed ntp connection. The ntp daemon is still in initialization phase. What is interesting is that you can see ntp traffic to and from the BIG-IPs. See SOL10240: Verifying NTP peer server communications, sample of a failed ntp connection.

We have seen something similar a couple of times (with two different customers) where the ntp traffic went via wrong interface and failed. The ntp server(s) were behind a routed connection from management interface. One of the BIG-IPs in the pair tried to reach ntp via data plane (TMM interface) and the other via management plane, even though the configs were identical in this respect. TMM ntp connection failed, and also resulted problems in config syncing.

In our case the suspect seemed to be a bug (or feature) explained in SOL10239: Traffic originating from management processes may not use the intended management address or management routes. Adding a static route for the ntp servers to the management routing table corrected the problem in those cases.