Err no mention of PTP at all? There are hardly any oscillators which can be plugged into a host which have any decent holdover. One should never expect them to

Err no mention of PTP at all? There are hardly any oscillators which can be plugged into a host which have any decent holdover. One should never expect them to run in reasonable time. Standard TCXO prob losses 100 ms a day. Rubidium loses 0.01 ms a day. Time providers include the perceived accuracy of the clock in the protocol so that the client can make a decision about which time source to use. Relying on the oscillator is never done in time critical applications except in emergency states where GPS is out of service. Of course a lot of people run relative clock domains, which is just a pretty bad idea for most applications.