> The difference in the protocol (L1_SYNC TLV vs SSM) seems to me quite small > when compared to the rest.
This is my concern, as this statement is false. SyncE describes an ITU-T network synchronization method for the distribution of frequency over a transport network, using the L1 physical layer clock (Ethernet or OTN). Details of the network limits, equipment clock requirements, protocol and architecture are contained in numerous ITU-T recommendations (G.826x). The use of the SyncE clock to assist PTP is described in G.8273.2 for T-BC/T-TSC (and also in G.8273.4 as a option for T-BC-P/T-TSC-P). In this case, the SyncE clock does not need to be coherent or congruent with the PTP clock. The L1_SYNC TLV is a Layer-1 based synchronization performance enhancement for PTP (described in Annex L of IEEE 1588-2019). The key aspect of the scheme illustrated by the high accuracy model is that the physical clock signal and the time of the PTP Instance are coherent. Yes, both methods can be used to syntonize the Timestamping Clocks in all PTP Instances to within the required tolerance with respect to the Grandmaster Clock, but how to use SyncE vs L1_SYNC in the protocol (ptp4l) is different - one is managed with the protocol (L1_SYNC) the other by it's own protocol (synce4l). I'm not arguing there could not be shared support code, but to the uninformed developer, synce4l could be mistaken for L1_SYNC (i.e. mistakenly use the PHC for "SyncE" clock management). Also, as Richard highlighted, the development of synce4l and ptp4l are mutual exclusive, so it does not make sense for the synce4l code submissions to be reviewed by the linuxptp development community, as they are not the right audience (as unlikely familiar with the ITU-T recommendations that synce4l must follow). Greg Greg Armstrong Principal System Architect, Timing Products Division Renesas Electronics Canada Limited Mobile: 1-613-218-9373 -----Original Message----- From: Miroslav Lichvar <mlich...@redhat.com> Sent: June 1, 2022 3:33 AM To: Greg Armstrong <greg.armstrong...@renesas.com> Cc: Richard Cochran <richardcoch...@gmail.com>; piotr.kwapulin...@intel.com; anatolii.gerasyme...@intel.com; andrzej.saw...@intel.com; linuxptp-devel@lists.sourceforge.net Subject: Re: [Linuxptp-devel] [PATCH 00/11] synce4l: add software for Synchronous Ethernet On Tue, May 31, 2022 at 02:42:00PM +0000, Greg Armstrong wrote: > This is the reason synce4l (based on an ITU-T physical layer protocol, > G.8264) should be separate from linuxptp project and be it's own standalone > project; so that it does NOT get confused with L1_SYNC TLV from IEEE > 1588-2019 (if/when it gets added to linuxptp). The HA profile's use of the > physical layer clock is not the same as ITU-T definition of SyncE. If synce4l remained specific to G.8264, the confusion could be avoided by renaming it to something else. (I don't have a suggestion at the moment.) There are plenty of conflicting options in linuxptp. The advantage of having both supported in linuxptp, no matter if the actual HW support is for both in synce4l or separately in ptp4l and synce4l, is that the support code can be shared. The difference in the protocol (L1_SYNC TLV vs SSM) seems to me quite small when compared to the rest. -- Miroslav Lichvar _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
