Their website links [1] to a presentation at Stanford [2]. Mendel Rosenblum briefly compares their concept with PTP at about 45:54. He says:

> Those people [fintech, etc.] are interested in our stuff, so obviously [that] means that thing [PTP] is not perfect for them. Part of the problem is, you’re trying to measure individual packets that are going through and get times. It means you have some clock there that you’re reading, and when it goes into the switch, and when it comes out, like, what is that clock doing in terms of its varying in frequency, and stuff like that. And then you get one sample and try to make things of it. It sorta pales in comparison to this big data approach we’re looking about.

This seems like a mischaracterization of PTP (802.1AS), which does use multiple samples to syntonize.

[1] https://www.clockwork.io/resource/ [2] https://www.youtube.com/watch?v=Opf9CBwP5R8

Not just that, but PTP switches modify the frame header to take into account the delta of the propagation delay through the switch. Everything is synced to the GM clock which is typically sync'd to GPS and your GM clock can itself be designed to ensure stability (e.g. temperature controlled oscillator). Furthermore, if reading the incoming data using a specialized NIC (they do this in finance, high speed trading for example) the timestamps are decoded in hardware. All this is done at the layer 2 level.

Applications like Spanner work with nanosecond-level time difference between datacenters. PTP works in microseconds and can even go up to a few milliseconds, making it useless for actual time sensitive use cases.

Spanner works fine with millisecond-level timestamps. Spanner needs accuracy, not precision: it relies on knowing the bounds on the the current time, which may be wide.

I think you are confusing PTP and NTP. NTP is in the range of low microseconds to a few milliseconds (with hardware time-stamping can actually do much better than that though), while PTP can synchronize time to better than 100ns.

A very good overview of the different solutions can be found here: https://ying-zhang.github.io/time/2021-02-revisiting-sync/ seems to be more of a pushing the envelope than snake oil to me, but what do i know

From the standpoint of having used 1588, I agree. I assume the greyed out nature of your post means it isn’t popular which is a little baffling given the truth in it.