Scott,
If you highlight a RTP stream, and go Statistics > RTP > Stream Analysis
It shows you both sides of an RTP conversation, and one of the
statistics is Jitter. I was looking at that and going back to the
inter-packet times and trying to figure out how Jitter is measured.
What I see in a lot of sessions is a growth and decline of Jitter across
the session, and usually one side is worse than the other. I am trying
to understand if jitter is an important variable in diagnosing voice
that goes into the toilet or just another interesting set of numbers.
Is this an estimated amount of jitter or is this absolute? Can I use
this as a sign that the voip traffic starts to degrade with only 10-15
ms of jitter. Specs on the equipment say that it can tolerate up to 100
ms of jitter before the buffer blows.
John G.
Scott Lowrey wrote:
I don't know how Ethereal measures jitter. (Does it? :)
RFC 3550 explains the concept and the required formulas for RTP/RTCP.
In a nutshell, jitter is a statistical measurement of the packet
inter-arrival time variation in a stream, and is expressed in units of
time.
There are other definitions of jitter, most dealing with electronic
communications and circuitry.
John Graves wrote:
Looking at the numbers for packets included in the RTP stream
analysis, it is not clear to me how jitter is measured. Can someone
point me to an explanation of this or explain how it is determined?
--
*Scott Lowrey*
Test Engineering Manager
NexTone Communications <http://nextone.com>
Gaithersburg, Maryland USA
/1.240.912.1369/
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--
John Graves
Dynamic Devices Inc.
781-245-9100
Your source for
Security, Wireless LANS & Wide Area Networking for converged Data, Voice and Video
