Re: Leveraging PTM

On Mon, Sep 04, 2023 at 01:34:48PM +0700, James Clark wrote:
> On Tue, Aug 22, 2023 at 5:58 PM Miroslav Lichvar <[email protected]>
> wrote:
> Currently it doesn't take advantage of PTP support in switches (i.e.
> > the correction field). It would have to be a unicast one-step E2E
> > transparent clock. Do you know any switches that can do that?
> >
> 
> The  IES3110-8TF-R web UI has some configuration options that suggest it
> supports unicast. See attached screenshot. I haven't experimented with it.
> It also has option to select one-step vs two-step, but I haven't
> experimented with that either.

That sounds promising. I'll order one and test it. It would be amazing
if this switch could do what 100x more expensive switches cannot.

> The main point of NTP-over-PTP is to enable HW timestamping of NTP
> > messages on PTP-only NICs. NTP doesn't need HW support in switches to
> > perform well when the network is (moderately) loaded. You can still
> > get sub-microsecond accuracy with good (non-PTP) switches if there
> > are not too many of them between the server and client.
> 
> 
> AS you say, it seems to perform well as is. But if it supported transparent
> switches, could the accuracy with NTP-over-PTP be as good as PTP?

Yes.

-- 
Miroslav Lichvar


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