Re: [Linuxptp-users] Transparent Clock

[Richard C. <ric...@gm...>]

On Tue, Aug 14, 2018 at 06:50:13PM +0000, Keller, Jacob E wrote:
> In hardware timestamping mode, I believe you just need a device which supports a single clock over multiple ports.

Right.  In practice, you can use the marvell link street devices, as
these already have kernel support.
 
> You can possibly use jbod mode too? I don't have any idea how much that would impact performance though.

Yes, but the performance would be poor.

Another way is to synchronize separate cards by means of HW.  I've
made a 3-port switch using 3 Intel i210 cards whose SDP inputs/outputs
are connected with a little wire.  You arrange a 1-PPS from one card
into others.  (I think I posted an example program some time ago.)
Then you run the PTP stack using the 'free_running' option.

It works pretty well.

HTH,
Richard