Sarah, David, I've changed my Minpoll and Maxpoll settings as suggested by David and now getting much better results (1 - 2 mS) when settled for the Meinberg Stratum 1 units. I'm also using Meinberg's version of NTP (6.2.6).
I'm still experimenting with settings, but it looks like my original post regarding the Ethernet over Power adapters might have been a red herring. Rob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Sarah White Sent: 13 February 2013 01:42 To: Discussion of precise time and frequency measurement Subject: [time-nuts] Network jitter with NTP David, Thanks for posting that. I'm currently doing some testing over wifi links myself, and found that page very useful. You do a really good job documenting your experiences with GPS-based NTP refclocks, and I appreciate all the hard work. I just wanted to ask though, are you compiling your own NTP now or what? http://www.davehart.net/ntp/win/x86.please.see.http.support.ntp.org-people-h art-win-x86/ but then under http://support.ntp.org/people/hart/win/x86/ ... most recent seems to be ntp-4.2.7p310 ^Basically, you were previously documenting use of dave hart's builds (overlaid over a meinberg ntp install or otherwise) Sorry rob, I don't have any experience with powerline adapters, but I'm treating your experiences (which don't seem to be promising) as a data point showing that they're no better for timing than using wifi... I'm getting high & unpredictable jitter with NTP over wifi as well (compared to cat 6 RJ-45 crossover cable directly between NTP servers) 1-20ms jitter for 5ghz band, 802.11n connection running with bitrate manually limited to 6mbit/s 5-70ms jitter for the 2.4ghz band, 802.11g connection running with bitrate auto-negotiation (up to 54mbit/s) ... My best case scenario for NTP jitter is about 0-5ms between a stratum 1 and a stratum 2 server directly connected via gigabit ethernet crossover (and the stratum 1 itself with a connected refclock seems to be at a baseline of 0-1ms most of the time, and rarely higher than 2ms) Those are just rough estimates based on casual observation, and I haven't done any long-term measurements yet like David Taylor's work... I'm "getting there" though it's coming slowly because of my trouble with learning curve in this area. --Sarah P.S. I renamed this post. The title "Possibly off topic - Jitter on Ethernet over poweradapters" seemed silly. > Rob, > > It's not quite clear which direction you are measuring. I take it > your Meinberg servers are "perfect" in NTP terms, and you are > monitoring from the house? Or vice-versa? Anyway, my first guess is > that jitter might be not dissimilar to Wi-Fi, in which case my > lightly-loaded Wi-Fi results might be a starting point: > > http://www.satsignal.eu/mrtg/performance_ntp_wifi.php > > Note the improvement with Windows-8 and the latest NTP (top graph, PC > Bergen), and the others are somewhat variable. > > Cheers, > David _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.