NTP Timekeeping - events, using NTP, performance graphs

Note on the performance graphs.  Please note, because I happen to use MRTG to gather and plot this data, and negative values aren't allowed, I needed to add a bias to the actual offset to derive the performance graphs.   An ideal timekeeper would therefore display a straight line at the mid-scale level.  The value plotted is the offset from the server clock that the NTP servers on each of the PCs reports when interrogated, every five minutes.  There appears to be an oddity with MRTG in that is looses small figures in the year data, so you may see a gradual drift upwards in some of the data, and that is probably just a recording artefact.
How I obtain this data.

Hardware and OS configuration

GPS 18 LVC
puck on roof
 paralleled RS-232
 
GPS 18x LVC
puck indoors
USB powered
   
|| || ||
Internet 
backup ==>
sources   
  PC Pixie
Stratum-1
FreeBSD 8.2
     PC Bacchus 
Stratum-1
Win 2000
    PC Feenix
Stratum-1
Win XP Pro
        PC Stamsund
Stratum-1
Win-8 64-bit
PC Molde
NTP Client
Win-7 64-bit
    Other
portable
devices
| | | | | |
Cable modem 
ISP: Virgin Media 
<=>  100Mb/s and 1Gb/s LAN <=> WiFi - Wireless-N
| | | | | | |
Internet 
backup ==>
sources 
PC Narvik
NTP client
Win XP Pro
PC Alta
Stratum-1
Win-7 64-bit
RasPi-1 
Stratum-1
Linux
  RasPi-2
Stratum-1
Linux 
PC Old-Feenix
 NTP client 
Win-XP Home
PC Puffin
NTP Client
 Vista Home 
  PC Ystad
NTP Client
 Win-7 32-bit 
  RasPi-3..6
Stratum-1
Linux 
|| || || ||
Sure GPS #2
puck indoors
USB powered
AdaFruit GPS
breakout board
indoor antenna
Trimble
Resolution SMT
indoor antenna
Chinese
U-blox
indoor antenna
GPS with
indoor
antennas

From April 2010, my primary NTP server is a FreeBSD server Pixie.  There are also two stratum-1 NTP servers, sometimes peered together, each fed from a separate GPS receiver.  One of the GPS receivers had its RS-232 output parallel-connected so that a temporary test could be made, and this was most recently used with a serial-to-USB converter box for testing the feasibility of using a USB connection where the PC has no serial port.  The parallel connection is also infrequently used for checking test versions of ntpd.exe on PC Bacchus, so Bacchus may well be a stratum-1 server at any particular time.  From April 2010, the FreeBSD server Pixie normally uses that parallel feed. The performance graph should be a good indicator!  Internet backup servers are configured for all PCs, with a much longer poll interval.  From February 2011 a Sure GPS module was added to the configuration - just as an experiment - and that is now feeding PC Feenix, with the paralleled RS-232 from the GPS-18 puck on the roof now feeding both the FreeBSD box Pixie and the Windows 2000 box, Bacchus.  In March 2011, a second Sure GPS board was acquired for testing, and used to check out 64-bit Windows-7 with a PPS kernel-mode driver.  In later 2012, two Raspberry Pi credit-card sized computers were obtained (RasPi-1 and RasPi-2 above), and tested with a couple of different GPS receivers.  More Raspberry Pi cards and GPS receivers have continued to be acquired and tested.

Active NTP Versions

Configuration changes and other events

Please note that some transients are caused by system reboots, e.g. after a security update, and these events are not usually individually recorded.

NTP Notes

For my own system

External links

Hardware suppliers - in alphabetical order - vendor-supplied descriptions

 

MRTG Multi Router Traffic Grapher
2.15.0 Tobias Oetiker <oetiker@ee.ethz.ch> and Dave Rand <dlr@bungi.com>