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

NTP offset graph PC Pixie
1.66GHz Intel Atom, 1GB
FreeBSD 8.0
NTP Server

ntpd 4.2.4p5-a(1)
GPS 18 LVC & PPS reference
NTP offset graph PC Feenix
Intel Pentium 4 1.9GHz, 1GB
Windows XP SP3
Main EUMETCast RX

ntpd 4.2.6
GPS 18 LVC GPS/PPS reference

NTP offset graph

PC Stamsund
2.8GHz Pentium 4 HT, 3GB
Windows XP Pro SP3
EUMETCast backup

ntpd 4.2.6
GPS 18x LVC GPS/PPS reference
NTP offset graph PC Bacchus
Intel Pentium III 550MHz, 512MB
Windows 2000 Server SP4
APT RX

ntpd 4.2.6
Synched from PC Feenix
(sometimes from GPS/PPS)
NTP offset graph PC Gemini
AMD-64 X2 4400, 3GB
Windows Vista Ultimate SP2
Test-bed

ntpd 4.2.6
Synched from PC Feenix
NTP offset graph PC Hydra
AMD 64 3200+, 2GB
Windows-7 Ultimate 64-bit
EUMETCast - test PC

ntpd 4.2.4p6 (273)
Synched from PC Feenix

NTP offset graph

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

ntpd 4.2.6
Synched from PC Feenix
NTP offset graph PC Puffin
Intel E8300 dual-core, 3GB
Windows Vista SP2
Interactive use

ntpd 4.2.4p6 (273)
WiFi synched from PC Feenix
NTP offset graph PC Torvik
Intel T3000 dual-core 1.8GHz, 2GB
Windows-7 Home Premium 32-bit
Interactive use

ntpd 4.2.4p6 (273)
WiFi synched from PC Feenix

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
 parallel RS-232
    GPS18 LVC
puck on roof
GPS 18x LVC
puck indoors
GPS 18 LVC
 parallel RS-232 
|| || ||        ||
Internet 
backup ==>
sources   
  PC Pixie
 Stratum-1 server 
FreeBSD 8.0
PC Feenix
 Stratum-1 server 
Win XP Home
== NTP
peer
== PC Stamsund
 Stratum-1 server 
Win-7 32-bit
    Serial => USB
converter
    Other
Portable
PCs
| | |        || |
Cable modem 
ISP: Virgin Media 
<==>  100Mb/s and 1Gb/s LAN <==> WiFi - Wireless-N
| | | |     || | |
Internet 
backup ==>
sources 
 PC Bacchus 
NTP client
Win 2000
PC Gemini 
NTP client
Win Vista 32-bit
      PC Hydra
 NTP client 
Win-7 64-bit
PC Narvik
NTP client
Win XP Pro
PC Puffin
NTP Client
 Vista Home 
PC Torvik
NTP Client
Win-7 32-bit

Normally, there are normally two stratum-1 NTP servers, 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 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.

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>