NTP performance, events, and notes on using NTP (or alternative presentation)

NTP offset graph PC Pixie
1.66GHz Intel Atom, 1GB
FreeBSD 8.2, NTP Server

ntpd 4.2.7
GPS 18 LVC GPS/PPS reference
NTP offset graph PC Feenix
Intel Pentium 4 1.9GHz, 1GB
Windows XP SP3, Main EUMETCast RX

ntpd 4.2.7
Sure GPS evaluation board reference

NTP offset graph

PC Stamsund
2.8GHz Pentium 4 HT, 3GB
Windows-7 Ultimate 32-bit, EUMETCast backup

ntpd 4.2.7
GPS 18x LVC GPS/PPS reference
NTP offset graph PC Alta
Intel i5-760 2.8GHz quad-core 8GB
Windows-7 64-bit, Interactive

ntpd 4.2.7
Sure GPS evaluation board reference
NTP offset graph PC Bacchus
Intel Pentium III 550MHz, 512MB
Windows 2000 Server SP4, APT RX

ntpd 4.2.7
Synced from PC Pixie/Feenix/Stamsund
(sometimes from GPS 18 LVC/PPS)
NTP offset graph PC Hydra
AMD 64 3200+, 2GB
Windows-7 Ultimate 64-bit, EUMETCast tests

ntpd 4.2.7
Synced from PC Pixie/Feenix/Stamsund

NTP offset graph

PC Molde
Intel Atom D330 dual-core HT, 4GB
Windows-7 64-bit, Compact Entertainment PC
ntpd 4.2.7

WiFi synced from PC Pixie/Feenix/Stamsund

NTP offset graph

PC Narvik
Intel E6600 dual-core 2.4GHz, 3GB
Windows XP Pro SP3, Interactive

ntpd 4.2.7
Synced from PC Pixie/Feenix/Stamsund
NTP offset graph PC Puffin
Intel E8300 dual-core, 3GB
Windows Vista SP2, Interactive use

ntpd 4.2.7
WiFi synced from PC Pixie/Feenix/Stamsund
NTP offset graph Portable PC Bergen
Intel T5450 dual-core 1.66GHz, 2GB
Windows-8 32-bit, Interactive use

ntpd 4.2.7
WiFi synced from PC Pixie/Feenix/Stamsund
NTP offset graph Portable PC Mercury
Intel Celeron 1.6GHz, 1.25GB
Windows-7 Home Premium 32-bit, Interactive

ntpd 4.2.7
WiFi synced from PC Pixie/Feenix/Stamsund
NTP offset graph Portable PC Torvik
Intel T3000 dual-core 1.8GHz, 2GB
Windows-8 32-bit, Interactive

ntpd 4.2.7
WiFi synced from PC Pixie/Feenix/Stamsund
NTP offset graph Portable PC Ystad
Intel N455 Atom, 2GB
Windows-7 Starter 32-bit, Plane Plotter use

ntpd 4.2.7
WiFi synced from PC Pixie/Feenix/Stamsund

Click on a graph for weekly, monthly and yearly data


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 graphs above (100ms for Gemini, 3ms for most PCs, and 500µs for the much more accurate PCs Feenix and Stamsund).  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
 
Sure GPS (1)
puck indoors
USB powered
GPS 18x LVC
puck indoors
USB powered
|| || || ||
Internet 
backup ==>
sources   
  PC Pixie
 Stratum-1 server 
FreeBSD 8.2
   PC Bacchus 
NTP client
Win 2000
  PC Feenix
 Stratum-1 server 
Win XP Home
== Potential
=== NTP ===
peers
== PC Stamsund
 Stratum-1 server 
Win-7 32-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
Raspberry Pi 1 
NTP client
Linux
    PC Alta
NTP client
Win-7 64-bit 
PC Hydra
 NTP client 
Win-7 64-bit
PC Puffin
NTP Client
 Vista Home 
  PC Ystad
NTP Client
 Win-7 32-bit 
|| ||
U-blox 6M
model board
indoors
Sure GPS (2)
puck indoors
USB powered

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.

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>