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How must intepret jitter value in cmr dump file

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Nov 6th, 2005
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My users reports some poor voice quality calls from PSTN. So i would troubleshoot this. In my cmr dump files i see only jitter values from 60 to 105 on connections from ip phones to my voice gateways. In all other cases this value is zero. How must interpret this value.



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gogasca Sun, 11/06/2005 - 17:26
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Ok,by definition, jitter is the difference in time between a packet´s expected arrival time and the time the packet actually arrives.

The jitter value in CMR is an stimate of the statistical variance of the RTP data packet interarrival time measured in ms and expressed as an unsigned integer.

The interarrival jitter is defined to be the mean derivation (smoothed absoluted value) of the difference in packet spacing at the receiver compared to the sender for a pair of packets, If the connection mode is "send only" the value is zero.

I widely recommend you to follow this link.


http://www.cisco.com/warp/public/779/largeent/it/ese/srnd.html

Check this part:

Network Infrastructure and Quality of Service

http://www-search.cisco.com/en/US/tech/tk652/tk698/tsd_technology_support_protocol_home.html


http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a008044750a.html#wp1043687



HTH

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