Re: [Linuxptp-users] (no subject)

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

On Tue, Jul 12, 2016 at 09:04:25PM +0200, Baya Oussena wrote:
> so my idea is to have two ptpd daemon as slave on the I/O board
> controller . One of the slave daemon will communicate with the front master
> and the other will communicate  with the other master at  back of the train.

Okay, so this is starting to make sense.  Another question:  Why does
the controller need both master times?  Is it for redundancy, or are
there two control loops, each synchronized to a different engine?
 
> I read about configuring domain. How could I use this idea.

So you only have one physical Ethernet port and one PHC, right?

You have a number of options, but I haven't tried any of them!

Here are a few ideas:

- There are different ideas out there about redundancy for PTP.
  Supporting any of these properly (within one process) would be quite
  some work, I should think.

- If you have only one PHC, then you must run one or both ptp4l
  instance with option "free_running 1".  You can still run your
  servos, using the data from the TIME_STATUS_NP management query.

- Simply using two different domains *might* work, if not with UDP
  then at least Layer-2 should work.

- You can also consider using two different transports to isolate the
  pairs, like UDP and Layer-2.

- Another idea is to run Layer-2 and isolate using VLANs.

Good luck,
Richard