Re: [Linuxptp-users] Issue when partner machine reboots

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

> -----Original Message-----
> From: Richard Cochran [mailto:ric...@gm...]
> Sent: Friday, May 04, 2012 6:06 AM
> To: Keller, Jacob E
> Cc: lin...@li...
> Subject: Re: [Linuxptp-users] Issue when partner machine reboots
> 
> On Thu, May 03, 2012 at 10:37:30PM +0000, Keller, Jacob E wrote:
> > I am having an issue when two machines are hooked up for ptp. If one
> > side reboots, the other side will never recover. This happens even
> > after the port timeout for reseting the fault. I think the reason this
> > occurs is because the socket for UDP goes invalid when the interface
> > goes down because of the loss of link. Is there a way to solve this so
> > that ptp4l would properly re-initialize when coming back? (attempt to
> > re-get the entire sockets etc?)
> >
> > Or is this just an invalid usecase and I should expect to have to
> > reset the daemon if its partners go down?
> 
> I am aware of the problem with a link down. Once the link does down, the UDP
> socket is no longer valid. I don't really understand why that should be the
> case, but probably we will just have to live with it.
> 
> I think the solution will be to open an additional netlink socket and poll for
> the link events. Link down should trigger a port fault, and then the port
> reset will then re-open the socket.
> 
> But that will take some time.
> 
> Thanks,
> Richard

Ok. For now I had validation try using the l2 ethernet packets. Reset doesn't
make these invalid. I believe the reason why UDP sockets go down is because the
IP address becomes invalid when the socket loses link. (Even if the same IP
address came back!) I like the idea of a netlink socket that could trigger a
proper port reset. Right now the default port reset doesn't appear to reset the
socket. (It does get a fault because it is unable to transmit,but the socket isn't
reset when it clears the fault.)