What is Network Congestion?

Have you ever found yourself staring at your screen, waiting for a webpage to load, or a file to download, only to be left frustrated by sluggish Internet speeds? It’s like being stuck in a traffic jam during rush hour, with no end in sight. But instead of honking your horn and yelling at other drivers, you might be wondering what’s causing the holdup. Well, fear not, fellow internet user, because the culprit might just be network congestion.

What is Network Congestion?

Network Congestion occurs when the traffic flowing through a network exceeds its maximum capacity. In most cases, congestion is a temporary issue with the network caused due to a sudden upsurge of traffic, however, sometimes, a network is continually congested, indicating a deeper problem. End-users perceive network congestion as a Network Slowdown or a very large delay in processing requests.

Network congestion is also a contributing factor in the following underlying issues:

  • High Latency – In a congested network, the time taken by a packet to reach its destination increases significantly, hence a higher latency rate is observed.
  • Connection timeouts – Ideally, the service should wait for the arrival of packets but in several cases, the connection terminates due to timeout.
  • Packet loss – Many packets cannot reach their destination if the network is congested, and will be dropped eventually due to timeout.

network congestion

Causes of network congestion

As with any troubleshooting process, understanding the root cause of network congestion is critical to resolving it. Some are more common than others, but it’s important to recognize all of them if you want to know how to manage them.

Unneeded traffic
Unneeded traffic is a common cause of network congestion. This will show up on networks in different ways. For example, someone streaming Netflix or YouTube videos at work would count as “unneeded” in a lot of situations and cause congestion since video traffic uses a lot of bandwidth. Other examples would be unsolicited traffic like advertisements or junk VoIP phone calls tying up your bandwidth. You should be able to identify unneeded traffic using your network management console.

Misconfigured traffic
A typical business network plays host to a lot of different traffic types. There’s broadcast traffic for network operation, multicast traffic for real-time media streams, and unicast traffic to support the data transfer, voice, and video functions we use every day. What we’d call “business critical” traffic can be any one of these types, but it’s important to understand and prioritize what it is. All traffic is intermixed, and in most networks they’re treated equally by network devices, meaning they all get an equal share of bandwidth. If this is not understood and configured correctly, problems are just a matter of time. This is where Quality of Service (QoS) protocols save the day.

Just like vehicles traveling down the highway, Quality of Service shares the same network, but in an unequal way. Traffic is classified and forwarded based on preset rules. QoS allows you to add a bit of special treatment to your business-critical traffic and real-time applications, getting them through congestion quicker.

Highway time again. If an oversized load is moving down the highway, it’s required to stay in the rightmost lane, where slow traffic is supposed to go. But if the oversized load wanders another lane… excessive traffic congestion is back. On the other hand, a presidential motorcade is going to have a police escort, allowing it to slip past everyone else with the highest priority.

Business-critical traffic
In a smooth-running network, the network manager will decide which types of traffic qualifies as “business-critical”, and reserve the bulk of the bandwidth for it. That could range from voice traffic on a VoIP network in a business call center to the order entry system for a large eCommerce business. The remaining bandwidth is left for other types of traffic.

Effects of Network Congestion

The consequences of network congestion can have far-reaching implications:

  • Increased Latency: Network congestion causes delays in data transmission, resulting in higher latency. Latency refers to the time it takes for data to travel from its source to its destination. Higher latency can hinder real-time applications such as video conferencing or online gaming, where responsiveness is critical.
  • Packet Loss: Congestion can lead to packet loss, where data packets are dropped due to network overload. Packet loss can trigger retransmissions, which further worsen congestion and degrade network performance.
  • Reduced Throughput:  Network congestion restricts the network’s throughput, which refers to the amount of data that can be transmitted within a given time period. Reduced throughput translates into slower download and upload speeds, hindering productivity and user experience.
  • Network Degradation: Congestion can cause the overall degradation of network performance. Applications that rely on the network, such as cloud services or data-intensive operations, may experience significant disruptions and become unusable during periods of congestion.

network congestion

How to solve network congestion problems

  • Traffic and bandwidth monitoring: The first step to resolve network congestion is to identify issues such as over-utilization of devices, insufficient bandwidth, and more. Monitoring networks also provide sufficient insights to identify problematic areas. You can also use network performance monitoring tools to identify such issues quickly. Once you get insights into your network performance and how data traffic flows, you can upgrade your devices, bandwidth, or network hardware to maximize the benefit.
  • Segmenting and prioritizing: Segmenting your network into small subnets increases efficiency by letting you prioritize traffic. This also helps you accurately monitor network traffic. Segmenting networks can reduce data traffic, producing a more viable network. Prioritization refers to the capacity to minimize traffic. Critical network traffic areas need more attention than others.


Network congestion poses significant challenges in computer networks, impacting performance, user experience, and productivity. By understanding the causes and effects of congestion and implementing proactive measures to mitigate its occurrence, network administrators can ensure smooth and efficient network operations. Regular network monitoring, capacity planning, traffic prioritization, and the use of congestion control mechanisms are essential components of congestion management.


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