NTPsec

scratchy

Report generated: Mon Jan 30 17:15:03 2023 UTC
Start Time: Sun Jan 29 17:15:03 2023 UTC
End Time: Mon Jan 30 17:15:03 2023 UTC
Report Period: 1.0 days

Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -1.455 -1.455 -1.086 -0.048 1.708 2.087 2.087 2.794 3.542 0.735 0.038 ms -2.744 6.762
Local Clock Frequency Offset -3.576 -3.576 -3.551 -2.933 -2.811 -2.803 -2.803 0.739 0.773 0.215 -3.006 ppm -3431 5.225e+04

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 248.614 248.614 260.255 355.839 583.150 668.815 668.815 322.895 420.201 96.972 384.117 µs 35.85 144.8

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 18.188 18.188 21.003 40.614 101.261 110.814 110.814 80.258 92.626 24.701 49.855 ppb 4.963 13.41

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -1.455 -1.455 -1.086 -0.048 1.708 2.087 2.087 2.794 3.542 0.735 0.038 ms -2.744 6.762

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 130.207.244.240

peer offset 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 130.207.244.240 -0.591 -0.591 -0.238 0.725 2.602 2.912 2.912 2.840 3.503 0.726 0.825 ms 1.525 5.018

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 18.26.4.105

peer offset 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 18.26.4.105 -0.783 -0.783 -0.435 0.594 2.183 2.696 2.696 2.618 3.479 0.666 0.610 ms 0.6931 4.31

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 192.5.41.41

peer offset 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.5.41.41 -3.637 -3.637 -3.122 -2.096 -0.380 -0.172 -0.172 2.742 3.465 0.719 -2.108 ms -71.75 322.9

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net)

peer offset 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -1.717 -1.717 -1.469 -0.352 1.342 1.575 1.575 2.811 3.292 0.726 -0.280 ms -6.296 15.56

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer offset 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.186 0.186 0.562 1.594 3.268 3.496 3.496 2.706 3.310 0.797 1.601 ms 4.72 12.69

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer offset 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -1.466 -1.466 -1.053 -0.147 1.702 1.954 1.954 2.755 3.420 0.703 -0.079 ms -3.753 9.175

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 130.207.244.240

peer jitter 130.207.244.240 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 130.207.244.240 0.077 0.077 0.083 0.224 0.915 1.991 1.991 0.832 1.914 0.322 0.355 ms 2.676 11.75

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 18.26.4.105

peer jitter 18.26.4.105 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 18.26.4.105 0.033 0.033 0.038 0.153 0.853 1.365 1.365 0.816 1.332 0.285 0.260 ms 1.783 6.227

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 192.5.41.41

peer jitter 192.5.41.41 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.5.41.41 0.166 0.166 0.188 0.497 2.013 2.079 2.079 1.825 1.913 0.546 0.756 ms 2.271 5.348

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net)

peer jitter 2001:470:0:2c8::2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 34.007 34.007 51.932 159.944 748.541 964.970 964.970 696.609 930.963 214.202 241.146 µs 2.16 6.48

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net)

peer jitter 2604:a880:2:d1::116:d001 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.041 0.041 0.065 0.303 0.996 1.765 1.765 0.930 1.724 0.364 0.433 ms 1.915 6.392

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov)

peer jitter 2610:20:6f15:15::26 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 0.054 0.054 0.141 0.401 1.262 1.639 1.639 1.121 1.585 0.348 0.507 ms 2.744 7.782

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -3.576 -3.576 -3.551 -2.933 -2.811 -2.803 -2.803 0.739 0.773 0.215 -3.006 ppm -3431 5.225e+04
Local Clock Time Offset -1.455 -1.455 -1.086 -0.048 1.708 2.087 2.087 2.794 3.542 0.735 0.038 ms -2.744 6.762
Local RMS Frequency Jitter 18.188 18.188 21.003 40.614 101.261 110.814 110.814 80.258 92.626 24.701 49.855 ppb 4.963 13.41
Local RMS Time Jitter 248.614 248.614 260.255 355.839 583.150 668.815 668.815 322.895 420.201 96.972 384.117 µs 35.85 144.8
Server Jitter 130.207.244.240 0.077 0.077 0.083 0.224 0.915 1.991 1.991 0.832 1.914 0.322 0.355 ms 2.676 11.75
Server Jitter 18.26.4.105 0.033 0.033 0.038 0.153 0.853 1.365 1.365 0.816 1.332 0.285 0.260 ms 1.783 6.227
Server Jitter 192.5.41.41 0.166 0.166 0.188 0.497 2.013 2.079 2.079 1.825 1.913 0.546 0.756 ms 2.271 5.348
Server Jitter 2001:470:0:2c8::2 (clock.nyc.he.net) 34.007 34.007 51.932 159.944 748.541 964.970 964.970 696.609 930.963 214.202 241.146 µs 2.16 6.48
Server Jitter 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.041 0.041 0.065 0.303 0.996 1.765 1.765 0.930 1.724 0.364 0.433 ms 1.915 6.392
Server Jitter 2610:20:6f15:15::26 (time-e-g.nist.gov) 0.054 0.054 0.141 0.401 1.262 1.639 1.639 1.121 1.585 0.348 0.507 ms 2.744 7.782
Server Offset 130.207.244.240 -0.591 -0.591 -0.238 0.725 2.602 2.912 2.912 2.840 3.503 0.726 0.825 ms 1.525 5.018
Server Offset 18.26.4.105 -0.783 -0.783 -0.435 0.594 2.183 2.696 2.696 2.618 3.479 0.666 0.610 ms 0.6931 4.31
Server Offset 192.5.41.41 -3.637 -3.637 -3.122 -2.096 -0.380 -0.172 -0.172 2.742 3.465 0.719 -2.108 ms -71.75 322.9
Server Offset 2001:470:0:2c8::2 (clock.nyc.he.net) -1.717 -1.717 -1.469 -0.352 1.342 1.575 1.575 2.811 3.292 0.726 -0.280 ms -6.296 15.56
Server Offset 2604:a880:2:d1::116:d001 (itchy.podsix.net) 0.186 0.186 0.562 1.594 3.268 3.496 3.496 2.706 3.310 0.797 1.601 ms 4.72 12.69
Server Offset 2610:20:6f15:15::26 (time-e-g.nist.gov) -1.466 -1.466 -1.053 -0.147 1.702 1.954 1.954 2.755 3.420 0.703 -0.079 ms -3.753 9.175
Summary as CSV file

Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of kurtosis. A normal distribution has a kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of skewness. Wikipedia describes it best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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