[e2e] ethernet jitter

"Alexander Carôt" alexander_carot at gmx.net
Sun Aug 20 03:20:09 PDT 2006

Hello to all,

after a period of silence from my side I have a question coming up.

I could tell you the whole story which would be pretty long so for now I just give you the conclusion : 

I observed that in ethernet networks, that jitter starts even when 30% of the bandwidth capacity is used and increases with the used bandwidth. At 30% it appears every 2-3 seconds with a variation of 1-2 ms which goes up to 15-25ms constantly at 90% used bandwidth. In all the cases there was enough bandwidth for my existing UDP-audio stream which I also measured the jitter with. The additional traffic was either TCP-traffic or additional UDP-traffic - all the same behavior.

In order to have the same preconditions I used a 10MBit/s line between two buildings on campus as the reference. Interesing is that the same behavior was observed with just two machines connected with a crossed cable and network cards configured with 10MBit/s.

Configured with 100MBit/s it was the same behavior but of course it required 10 times more traffic to reach the 30% load.

Can anyone confirm these measurements or do you know papers concerning this subject ? 

I'd appreciate any hint from you.

Thanks a lot in advance,

-- A l e x
Dipl.-Ing. Alexander Carôt
Email : Alexander at Carot.de
Tel.: +49 (0)177 5719797

phd-candidate at www.isnm.de

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