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What is Network Congestion?

Network congestion happens when a network node or link carries more data traffic than it can efficiently handle, usually leading to reduced quality of service, packet loss, and high latency. When demand for bandwidth exceeds capacity, it causes slow buffering, and timed-out congestions.

Think of it just like traffic congestion on a highway at rush hour. There are too many cars (data packets) trying to use the same road (network link) at the same time. So, traffic slows to a crawl. Common causes of network congestion are: too many devices sending data simultaneously, bottlenecks at routers or switches that can’t process fast enough, and sudden traffic spikes. 

A few of the ways networks try to manage this congestion is with TCP congestion control, a protocol that automatically slows transmission rates when it detects packet loss. Quality of Service (QoS) routers that prioritize certain traffic types over others can also help mitigate the loss of service quality. Internet service providers (ISPs) have also been known to throttle certain types of traffic during peak hours. Another solution is content delivery networks (CDNs), which distribute load across many servers geographically.