Jitter and intrapacket delay

[Urtho]

On 2007-07-17, at 18:38, Carter Bullard wrote:

> Hey Urtho,
> Remember, the values are in uSec, and jitter is really std  
> deviation, rather
> than variance, so the number could have been much larger.
> With all the loss, yes you can get stdev's that are astronomical.   
> Did you
> calculate this from a packet file, like I suggested?   With a  
> packet file, you
> can actually go back and verify the numbers.

variance[ms] = stddev^0.5/1000 ?

>
> not sure that I understand the NaN in the last one though.  If you
> aggregate the data too much, you do end up with overflow conditions
> on the sum of squares that we are carrying along.  The value is a
> 64-bit float, so it should carry a lot of data, but when dealing with
> uSec differences, the sum of squares can get pretty high pretty fast.
>

I get NaNs probably because of 60s flow collection interval instead  
of default 5.
Also the insane values are present only in case of a microflow - eg 9  
packet RTP flow :)

So I wrote a simple perl filter that shows me only abnormal stuff and  
I see that a lot of my (long) calls have non standard 50pps RATE.
Will have to investigate.

Small question - does destination packet loss mean - packet lost in  
src->dst dir or quite the opposite ?

Anyway - thanks for the great piece of software !!!!

Urtho,