Re: [Linuxptp-users] List of Boundary clocks

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

On Thu, Mar 21, 2013 at 01:28:04PM +0100, Mozhdeh Kamel wrote:
> 
> Can anyone help me with the list of boundary clocks?I wonder whether
> boundary clocks are simple switch with hardware time stamping? what special
> characteristics it must have?

A boundary clock (BC) is more like a router than a switch. It must
intercept incoming PTP messages, and it does not forward them (except
for management messages).

Although linuxptp is designed to work as a BC, I don't know of any
that are using linuxptp. If you want to try the code out, then you
need a computer with two or more ports, all of which share a common
PTP Hardware Clock (PHC). I can think of two ways to do this.

1. Use a computer whose ports all support SW time stamping. This will
   not perform very well, but at least you can see how it works.

2. Get a computer with true HW time stamping support. Note that you
   cannot just use a box with multiple PCI cards, for example. The
   ports must all share *one* clock.

   Some ready made system on chips have this, like the Freescale P2020,
   the MPC8306, and the MPC8309. If you have one of these kits, then
   the ptp4l program should work fine.

   Another possibility is to use the DP83640 PHY, but you must make
   sure to connect the GPIOs in your design so that the PHYs can
   synchronize each other.

HTH,
Richard