Jitter is a variation in packet transit delay caused by queuing, contention and serialization effects on the path through the network. In general, higher levels of jitter are more likely to occur on either slow or heavily congested links. It is expected that the increasing use of “QoS” control mechanisms such as class based queuing, bandwidth reservation and of higher speed links such as 100 Mbit Ethernet, E3/T3 and SDH will reduce the incidence of jitter related problems at some stage in the future, however jitter will remain a problem for some time to come.
Root cause of Jitter
There are mainly two types of jitter
1. Type A – constant jitter. This is a roughly constant level of packet to packet delay variation.
2. Type B – transient jitter. This is characterized by a substantial incremental delay that may be incurred by a single packet.
3. Type C – short term delay variation. This is characterized by an increase in delay that persists for some number of packets, and may be accompanied by an increase in packet to packet delay variation. Type C jitter is commonly associated with congestion and route changes.
References:
http://www.voiptroubleshooter.com/indepth/jittersources.html
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