Thanks for your quick reply! Would you be ok to tell me which commercial switches are very slow to process ptp in the transparent mode ?
Our boundary clocks in each technical room will be based on mellanox hardware (but not mellanox branded, it's OEM provided by our partner) with one single Netgear 4350 attached to it, with a few devices connected to it audio devices, probably less than 20 clients) Thanks Surya Le lun. 13 nov. 2023 à 02:40, Richard Cochran <richardcoch...@gmail.com> a écrit : > On Sun, Nov 12, 2023 at 09:57:56PM +0100, Surya Arby wrote: > > > we are considering the use of linux-based switches (hardware timestamping > > provided in the ASIC, linuxptp will be used), the GM will be connected to > > the switch, and all ports will be BC, > > In PTP land, switches and Boundary Clocks are not the same (as you > probably already know, but you seem to conflate the two in this mail) > > > I was wondering if there was any known > > limit to the number of PTP clients behind a BC port in the code ? (an > > intermediate PTP-transparent switch will be used to connect several > clients > > to the BC port) > > There are no hard coded limits in the code. Because the program is > single threaded, there is a practical upper limit somewhere. > > BC mode is essentially stateless WRT the number of clients, so that > memory usage is not a concern. The only limitation is the rate at > which Delay Requests can be handled, as the responses are serialized > by the single threaded ptp4l program. > > TC needs a bit of state for each message needing residence time > correction, and so memory use will increase with the number of PTP > clients. Also, when ptp4l runs in TC mode, the frame residence time > will likely be in the single digit millisecond range. Reducing that > might be challenging, but maybe nobody cares about the residence time > duration? (FWIW I've seen commercial Transparent Switches where the > residence time is in the double digit millisecond range.) > > HTH, > Richard > > >
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