Re: [Linuxptp-users] Grandmaster Auto-Negotiation and Reconfiguration of phc2sys to ptp4l Synchronization

[Keller, J. E <jac...@in...>]

Hi Harold,

On Thu, 2015-08-13 at 20:38 +0000, Harold Lapprich wrote:
> To Whom It May Concern,
>  
> Have need for PTP-to-NTP and/or NTP-to-PTP synchronization in the
> opposite direction. When ntpd is used to synchronize the system
> clock, phc2sys can be configured to synchronize PTP grandmaster clock
> to the system clock, ptp4l configured to be the grandmaster clock and
> distribute the time from the system clock via PTP.
>  
> In the case of a PTP slave device phc2sys needs to be used to
> synchronize the system clock to the PTP hardware clock.
>  
> The way the linuxptp applications ptp4l and phc2sys have been written
> a master can drop out and a new one negotiated. And on top of this
> phc2sys recovery takes a while but does recover providing a real
> robust design. But when ptp4l is synchronized to the phc2sys/system
> -time on the master and phc2sys synchronized to ptp4l on the slave
> side a drop out of the grandmaster and negotiation of grandmaster
> will mess up ptp4l to phc2sys for system clock synchronization. The
> only way to avoid this is to be able to recognize a new grand master
> has been negotiated so ntpd is used by the new grandmaster clock
> system to properly configure the phc2sys to ptp4l synchronization. Is
> there any way of detecting the renegotiation of the grandmaster using
> the tools/applications within linuxptp (ideally it would be nice to
> have the system auto-negotiate the grandmaster and reconfigure
> phc2sys to ptp4l synchronization)?
>  
> Harold
>  
>  

I suggest you take a look at the phc2sys -a auto configuration mode
along with timemaster which I believe is provided inside the LinuxPTP
project. This should provide the necessary configuration to use
something like chronyd in this manner you describe.

Regards,
Jake