Wireshark · Ethereal-users: Re: [Ethereal-users] Jitter Measurement

[John Graves <jhgraves@xxxxxxxxxxxx>]

Scott Lowrey wrote:
> According to the original RFC, jitter should be measured by comparing 
> the interarrival time at the receiver with the difference in sample 
> times as measured by the sender.  The former is obtained by measuring 
> discussion a few months back on that subject:
>
> http://www.ethereal.com/lists/ethereal-users/200411/msg00051.html
Scott,

Thank you.   That is the information I was looking for and it confirms 
my suspicions as to the method of computation.  My fear was that 
Ethereal was understating jitter and that is still not clear.  In a lab 
setting, you would have the ability to both measure and control 
differences in arrival time by absolute methods.  The question still 
remains about how jitter is calculated by equipment manufacturers.  It 
is not enough to know that VoIP falls apart at 100ms of jitter, and that 
you should set the jitter buffer slight more than the average jitter on 
the circuit.  Ah well.....the mysteries of IT...er life

John G.