-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 As an aside, I would love to see a presentation on keeping time in sync on Linuxen, with a deep dive into the innards of NTP. Sounds like GTALUG has the talent pool for such a presentation...
- --Bob. On 16/03/15 12:33 PM, Mike wrote: > PTP at IP (layer 3) still needs hardware-based (PHY or MAC level) > timestamping in order to achieve O(nanoseconds) and O(ppb) > performance in phase and frequency. The best performance is > achieved with this support at every link that time sync data > traverses. > > Telco nerds use Synchronous Ethernet besides... > > Mike > > On Mon, Mar 16, 2015 at 8:16 AM, David Thornton > <[email protected]> wrote: > >> "There is PTP support in Linux, but you need an Ethernet card >> with the right timestamping feature plugged into a switch that >> does PTP too." >> >> You can do PTP over IP but I understand you can also deploy >> "dedicated" networks that JUST do PTP ( no ip ). >> >> It is the dedicate nets you are talking about ? >> >> The sexiest PTP hardware I've seen is the solarflare stuff. >> >> David >> >> >> >> >> On Sun, Mar 15, 2015 at 5:58 PM, Anthony de Boer <[email protected]> >> wrote: >> >>> Stewart C. Russell wrote: >>>> On 2015-03-14 10:09 PM, David Thornton wrote: >>>>> My finance client's use ptp not ntp. >>>> >>>> Is PTP particularly hard to use? It looks like an ISO >>>> standard, so will likely be fiddly but complete. >>> >>> Accuracy numbers in PTP are measured in nanoseconds, while the >>> NTP world talks milliseconds. So if you have that sort of >>> accuracy requirement (power system phasors, etc) you probably >>> want PTP with the appropriate dedicated hardware, while >>> garden-variety Unix admins just want log records to show up >>> with the right second. >>> >>> There is PTP support in Linux, but you need an Ethernet card >>> with the right timestamping feature plugged into a switch that >>> does PTP too. >>> >>> Meanwhile, ntpd is getting a bit long in the tooth[0] and the >>> ntimed project looks interesting. >>> >>> [0] "support for hardware clocks EBay has never heard of" >>> >>> -- Anthony de Boer --- Talk Mailing List [email protected] >>> http://gtalug.org/mailman/listinfo/talk >>> >> >> >> --- Talk Mailing List [email protected] >> http://gtalug.org/mailman/listinfo/talk >> >> > > > > --- Talk Mailing List [email protected] > http://gtalug.org/mailman/listinfo/talk > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) Comment: Ensure confidentiality, authenticity, non-repudiability iEYEARECAAYFAlUM16kACgkQuRKJsNLM5eoKhgCg/zqAXoZpc5f/M5l1eo4SrZKr EXsAn0UERQBOidCsekZvI2hrYVkbn7bD =9YUp -----END PGP SIGNATURE----- --- Talk Mailing List [email protected] http://gtalug.org/mailman/listinfo/talk
