Re: [Linuxptp-users] List of Boundary clocks

[Mozhdeh K. <kam...@gm...>]

I mean, I am thinking of having several virtual machines (such as VBox),
run the linux PTP project on each on them. and I can connect them together
through GRE or other tunnel. Use TC on linux or NeteM to add delay and
jitter .

BR,
Mozhdeh


On Sat, Apr 6, 2013 at 12:18 PM, Richard Cochran
<ric...@gm...>wrote:

> On Thu, Apr 04, 2013 at 01:04:49PM +0200, Mozhdeh Kamel wrote:
> >
> > Actually I am going to design a network to run the PTP protocol(with BC).
> > But the main problem for me is I don't access to real hardware. I though
> > maybe using a PC with several network card (HW time stamping) would help.
> > But, share clock is another problem!!!
>
> With a small modification to ptp4l, you might be able to use multiple,
> separate PCI cards together as a BC. We just need to disable* the check
> in ptp4l that makes sure all the PHC clocks are the save. For example:
>
> port1 eth0 /dev/ptp0 - ptp4l controls this clock, port connected to GM
> port2 eth1 /dev/ptp1 - phc2sys instance 1 slaves this clock to /dev/ptp0
> port3 eth2 /dev/ptp2 - phc2sys instance 2 slaves this clock to /dev/ptp0
>
> In order to test how well phc2sys synchronizes the internal clocks,
> you could run three separate ptp4l instances, one per port, and
> connect all the ports to the same master through a switch. If you set
> the ptp4l "free running" option on ports 2 and 3, then you can measure
> the time error between the phc2sys servo and the PTP network time.
>
> What PTP hardware do you have to choose from?
>
> > Now, I am thinking of possibility to use of virtual switch, router and
> NIC
> > .. Is anyone have experience of it?? Is it possible?
>
> I am not sure what you mean by "virtual" here.
>
> HTH,
> Richard
>
> * Or you could use a Linux kernel version before 3.5, without
>   ETHTOOL_GET_TS_INFO support.
>
>


-- 
*Mozhdeh *