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

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From: John Graves <jhgraves@xxxxxxxxxxxx>
Date: Mon, 11 Apr 2005 23:30:33 -0400


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.