Congestion Control / Avoidance

Modern networks use congestion control and network congestion avoidance techniques to try to avoid congestion collapse. These include: exponential back off in protocols such as 802.11's CSMA/CA and the original Ethernet, window reduction in TCP, and fair queuing in devices such as routers. Another method to avoid the negative effects of network congestion is implementing priority schemes, so that some packets are transmitted with higher priority than others. Priority schemes do not solve network congestion by themselves, but they help to alleviate the effects of congestion for some services.