Congestion

In modern networks, avoiding congestive collapse involves the application of network congestion avoidance techniques along with congestion control, such as:

• Exponential backoff protocols that use algorithm feedback to decrease data packet throughput to acceptable rates
• Priority techniques to allow only critical data stream transmission
• Allocation of appropriate network resources in anticipation of required increases in data packet throughput

Congestion has been described as a fundamental effect of limited network resources, especially router processing time and link throughput. Traffic directing processes, performed by routers on the Internet and other networks, use a microprocessor. Cumulative router processing time greatly impacts network congestion. In fact, intermediate routers may actually discard data packets when they exceed its handling capability. When this occurs, additional data packets may be sent to make up for unreceived packets, which exacerbates the problem. Network congestion often leads to congestion collapse.

Avoiding network congestion and collapse requires two major components:

• Routers capable of reordering or dropping data packets when received rates reach critical levels
• Flow control mechanisms that respond appropriately when data flow rates reach critical levels