> -----Original Message----- > From: Petr Machata [mailto:pe...@mellanox.com] > Sent: Thursday, June 20, 2019 1:50 AM > To: linuxptp-devel@lists.sourceforge.net > Subject: Re: [Linuxptp-devel] [Linuxptp-users] forcing PASSIVE role for a > port? > > > Keller, Jacob E <jacob.e.kel...@intel.com> writes: > > >> > From: Sanjay Bhandari [mailto:san...@ziffusion.com] > >> > Is there a way to set a port in the PASSIVE role with ptp4l? > >> > > >> > Essentially, we want to listen in on the protocol, but not generate ANY > >> > protocol > >> messages ourselves. Nor do we want to set the PHC from any master. > >> > > >> > Is there a way to achieve this? > >> > >> Does using free_running, along with --slave-only do what you want? > >> > >> I don't think you're going to get a mode which only listens and doesn't do > >> ANY > >> messages back out... For that I'd suggest tcpdump and implement a filter > >> that can > >> read the PTP messages and show relevant fields for you. > > WireShark has some related display filters, for example: > > $ tshark -i sw1p49 -Y 'ptp.v2.messageid in {0 8}' > Capturing on 'sw1p49' > 1 0.000000000 2001:db8:1::1 → ff0e::181 PTPv2 108 Sync Message > 2 0.000079209 2001:db8:1::1 → ff0e::181 PTPv2 108 Follow_Up Message > 7 0.500071357 2001:db8:1::1 → ff0e::181 PTPv2 108 Sync Message > 8 0.500152168 2001:db8:1::1 → ff0e::181 PTPv2 108 Follow_Up Message >
Yea, if all you want to do is sniff, this would work. By design, syncing even as a slave requires you to send at least some packets out to help calculate the delay and offset. Thanks, Jake _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
