[Linuxptp-users] Want to reduce offset (which is distance dependant) between boundary clocks.

[aniket <an...@gm...>]

Hi...very good afternoon to all.

Myself Aniket Hendre, project engineer C from National Centre for Radio 
Astrophysics, India.

I am synchronising two boundary clocks using ptp4l. I found that the 
offset at the slave PHY clock from master PHY clock varies with respect 
to distance between these clocks.

In my first experiment,  master and slave are 2 Km away from each other. 
In this case I got offset at slave PHY clock around 50 nano second.

In second experiment I relocate my slave around 20 Km from master where 
I got offset of 150 nano seconds.
 
Ideally the offset between PHY clocks should remain constant though we 
are varying distance between them (correct me if I am wrong).

For both experiments mentioned above I am issuing following common 
command 
ptp4l -i eth1 -m. I have connected these two machine using fibre optic 
cable with media converter on both ends. My both ethernet ports are 
supporting IEEE1588.

Do we need to specify any parameter (which is distance dependant) while 
issuing above command? Because there are many PROGRAM AND CLOCK OPTIONS 
in ptp4l. Do we need to set any specific option?

Please help.

Thanks in advance
Aniket Hendre