Causes, impacts, and countermeasures of congestion
Congestion occurs on a link or node when traffic size exceeds the processing capability of the link or node. It is typical of a statistical multiplexing network and can be caused by link failures, insufficient resources, and various other causes. Figure 13 shows some common congestion scenarios.
Figure 13: Traffic congestion causes
Congestion can bring the following negative results:
Increased delay and jitter during packet transmission.
Decreased network throughput and resource use efficiency.
Network resource (memory, in particular) exhaustion and system breakdown.
Congestion is unavoidable in switched networks or multiuser application environments. To improve the service performance of your network, take measures to manage and control it.
One major issue that congestion management deals with is defining a resource dispatching policy to prioritize packets for forwarding when congestion occurs.