The value of tmnxPtpMasterClockAddress indicates, along with
the value of tmnxPtpMasterClockAddressType, the IP address of the
Parent Clock.
If tmnxPtpMasterClockAddressType and tmnxPtpMasterClockAddress
specify an IPv4 address of 0.0.0.0, this indicates that the
local clock is currently the parent/master clock.