Jitter in Voice Network

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May 26th, 2007
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Dears;


i have attached network design and it is working but i face Delay variations on the Routers at both sites


FYI: R0 is connected to R4 through two Satellite links with delay around 600-900 ms and one link to R3 through satellite link with same delay.


same R2 is connected to R3 through two sat. links with 600-900 ms delay and one link to R4 with same delay.


also there load balancing on R0 and R2 with CEF enabled per source and destination ports.

i do not know what problem is .

can you help me to compensate that jitter effect.


Regards //



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paolo bevilacqua Sun, 05/27/2007 - 08:49
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Hi,


High delay and jitter are characteristics of satellite links and cannot be eliminated.


However, you can tune the "playout-delay" to somewhat conceal the above. Please see:

http://cisco.com/en/US/products/sw/iosswrel/ps1834/products_feature_guide09186a008008033c.html


Hope this helps, please rate post if it does!

teodorgeorgiev Wed, 05/30/2007 - 01:59
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The latency on satellite links surely can not be eliminated, but I can not say the same for the jitter. Non-inclined satellites with CIR will never cause any jitter.



paolo bevilacqua Wed, 05/30/2007 - 18:51
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Hello,


In reality jitter is due to traffic competing for the same link. Any variation in time spent in queue will cause jitter. On satellite links, unless you have SCPC (very expensive), you will always be sharing the link with someone else.

CIR only guarantees a delivery rate over time, not a delivery time.

davecisco Fri, 06/01/2007 - 08:34
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Based on your diagram and what you say above, it seems to me that the voice calls are double hopping (over the sat twice)? If this is correct than your delay is doubled and you will certainly have issues.


With only one sat hop you should be able to get pretty good voice (we are doing it on our network) with voice delay being the only real noticeable issue.


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