What are congestion, delay, and jitter?
A. An interface experiences congestion when it is presented with more traffic than it can handle. Network congestion points are strong candidates for Quality of Service (QoS) mechanisms. The following is an example of typical congestion points: Network congestion results in delay. A network and its devices introduce several kinds of delays, as explained in Understanding Delay in Packet Voice Networks. Variation in delay is known as jitter, as explained in Understanding Jitter in Packet Voice Networks (Cisco IOS Platforms). Both delay and jitter need to be controlled and minimized to support real-time and interactive traffic.
