nanog mailing list archives
Re: Recommendation on NTP appliances/devices
From: Dan Drown <dan-nanog () drown org>
Date: Fri, 04 Apr 2014 10:57:24 -0500
Quoting Julien Goodwin <nanog () studio442 com au>:
Show my anything short of a classic SONET transmission system (orperhaps sync-E) where you actually have something with jitter that low [tens of microseconds].
Since you asked, here you go: http://i.imgur.com/DvMJd5y.pngTwo EndRun Unison GPS NTP servers, one in New York metro and one in London metro. They're connected via 10G over dark fiber (along with a bunch of networking gear doing more than just measuring time). Measurements taken from ntp running on the New York server, the blue line is the offset between the two clocks (in ms, left labels) and the pink line is the rtt (in ms, right labels).
90th percentile of the offsets is 34 microseconds, and 10th percentile is 5 microseconds.
You can see a spike in one-way latency near sample "590". Most likely culprit is of one of the firewalls being busy (there's two in this path).
Current thread:
- Re: Recommendation on NTP appliances/devices, (continued)
- Re: Recommendation on NTP appliances/devices Rob Seastrom (Apr 03)
- Re: Recommendation on NTP appliances/devices Chris Adams (Apr 03)
- Re: Recommendation on NTP appliances/devices Rob Seastrom (Apr 03)
- Re: Recommendation on NTP appliances/devices George Herbert (Apr 03)
- Re: Recommendation on NTP appliances/devices Will Orton (Apr 03)
- Re: Recommendation on NTP appliances/devices Saku Ytti (Apr 03)
- Re: Recommendation on NTP appliances/devices Julien Goodwin (Apr 04)
- Re: Recommendation on NTP appliances/devices Saku Ytti (Apr 04)
- Re: Recommendation on NTP appliances/devices Julien Goodwin (Apr 04)
- Re: Recommendation on NTP appliances/devices Saku Ytti (Apr 04)
- Re: Recommendation on NTP appliances/devices Dan Drown (Apr 04)
- Re: Recommendation on NTP appliances/devices Rob Seastrom (Apr 03)
- Re: Recommendation on NTP appliances/devices bmanning (Apr 03)