[Linuxptp-users] Resync to master after network outage

[Petr Kulhavy]

Hi,

I have experienced an odd situation with ptp4l.
I have two devices running ptp4l, one slave-only and the other one master.
They were synchronized and then the network was out for few hours
(switch powered off).
After regaining the network the slave was synchronised to itself and
didn't want to resync to the master as I expected.
After restarting ptp4l on the slave it perfectly synchronized to the master.

Why is that?


The slave configuration is:
slaveOnly 1
delay_mechanism Auto
network_transport UDPv4
time_stamping hardware
step_threshold 1.0

The master runs as: ptp4l -A -i eth0


Thanks
Petr

[Richard Cochran]

Post by Petr Kulhavy
After regaining the network the slave was synchronised to itself and
didn't want to resync to the master as I expected.

A slave cannot synchronize to itself.

Post by Petr Kulhavy
After restarting ptp4l on the slave it perfectly synchronized to the master.
Why is that?

I guess that no announce message got through to the slave. Did you
check it with tcpdump/wireshark?

Thanks,
Richard