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IPSLA jitter Statistic not correct?

eric10316

I have tried to compare the raw data from Solarwinds and the statistics in the switch.

The jitter(S-to-D and D-to-S) results are totally different even I have set the same time interval.

Have any idea about this problem ?

THANKS

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tom.rybka

Do you mean a single UDP Jitter operation providing metric values or two directional UDP Jitter operations from S to D and vice versa. Can you be please more specific about the differences? Have you compared the most recent stats at the same moment (note that IPSLA Manager polls stats updates twice as fast as operation frequency is, thus there may be certain delay for it to get refreshed)?

Thanks.

eric10316

Yes, this is a single UDP Jitter operation.

The value comes from the device is shown below:

However, the result comes from SolarWinds IP SLA Manager is not the same:

----------------------------------------

Here are the basic information:

Interval Between Packets: 20
Number Of Packets: 20
Request Packet Data Size: 64

tom.rybka

I have couple of additional questions:

Which version of IPSLA Manager do you use?
Which table/view have you captured the second picture from?

eric10316

1. ipsla manager 3.5.1

i exported the raw data of "Min/Max/Avg graph of Jitter (Source → Target)" which sampling interval is 1 minute.

For reference:

The UDP Jitter setting is:

Frequency: 60s

Interval Between Packets: 20

Number Of Packets: 20
Request Packet Data Size: 64

tom.rybka

First of all, your screenshot highlights the operations statistics for directional latency whereas you reference to jitter values in the text.

If I consider the jitter values from the screenshot, it is not really the same number, but it is close to the AVG value. Now, I am not sure what formula does the router use for calculation of the values, anyway IPSLA Manager use the following MIB OIDs' values from the switch to calculate it on its own (and it may explain certain differences):

jitterSD = jitterSumSD / jitterNumSD

where

jitterSumSD = rttMonLatestJitterOperSumOfPositivesSD + rttMonLatestJitterOperSumOfNegativesSD
jitterNumSD = rttMonLatestJitterOperNumOfPositivesSD + rttMonLatestJitterOperNumOfNegativesSD

(Please note that the values are in milliseconds in the database.)

eric10316

I would also like to know the calculating method on the latency and one way delay.

Thanks

mcbridea

Eric,

Thomas shows the calculations a few posts up from this one.

Andy

tom.rybka

Appending the formulas for latency and one-way delays:

Latency = rttMonLatestJitterOperRTTSum / rttMonLatestJitterOperNumOfRTT

OneWayDelaySD = rttMonLatestJitterOperOWSumSD / rttMonLatestJitterOperNumOfOW

OneWayDelayDS = rttMonLatestJitterOperOWSumDS / rttMonLatestJitterOperNumOfOW