Network Congestion Troubleshooting Guide

The modern business environment requires a fast, stable, and secure network infrastructure that can connect all its digital devices – be they locally or remotely located. It also requires a high uptime so clients can stay in contact with the business. Thus, issues like severe network congestion can severely affect a business’s overall performance.

Definition of network congestion

The simple definition of network congestion is that it is what occurs when a network is overburdened with more data packet traffic than it can handle.

Basically, a backup of data packets occurs when too many communication and data requests are simultaneously made over a network that doesn’t have enough bandwidth – which could have been reduced due to various reasons – to carry it all at once.

Although network congestions are usually a Local Area Network (LAN) issue, they can also occur on the Internet in cases where cloud computing, remote access, or hybrid networking architectures are involved.

Problems caused by network congestions

Some problems that may arise because of a congested network would be:

  • Slowing down of data packets delivery
  • Timeouts causing data packets to be dropped
  • Impossible for connected devices to communicate with one another
  • The inability of new devices to join the network or for clients to contact the business for service processing or business transactions

Depending on the length of the network’s downtime, the business could lose revenue and their clients’ trust. The worst-case scenario can occur if, and when, network congestion isn’t remedied in time and leads to the total collapse of the business’ communication and processing capabilities resulting in substantial losses.

Causes of network congestions

The main causes of network congestions include (but are not limited to):

  • Improperly configured network connectivity devices or poor network architecture, segmentation, or design causing packet collisions, data loss, broadcast storms, and IP conflicts.
  • Poor network growth forecasting or not anticipating trends, traffic surges, and resource consumption.
  • Low bandwidth limitations creating unpredicted data bottlenecks.
  • Too many users, applications, or devices using the network.
  • Misconfigured or zealous antiviruses running in excess and over-consuming resources and slowing everything else down.
  • Outdated, legacy, faulty, and incompatible network devices being used on a modern network and then being expected to keep up with the performance of the latest software and hardware technology.
  • Security breaches like Cryptojacking – hacking devices and networks for illegal mining of Bitcoins – consuming a lot of computing power.

As we can see, the causes for the congestion themselves have their roots in just as many faults – both internal and external – and the only way to stop them is by keeping a vigilant eye on the whole network setup.

Effects of network congestions

Now, as can be imagined, these conditions would hamper the smooth workings of business; especially if they cater to online clients or have remote workers that need to stay in constant contact with the HQ. But, there’s more; they could be the reason for:

  • The inability for devices – internal or external – to join the network and thus causing communication errors between applications and servers that may need to synchronize regularly, for example.
  • Deterioration of services and processes can affect the business’ ability to deliver on products and services.
  • The total collapse of the network – especially if the network congestion is not contained, managed, and fully remedied.

If regular bouts of network congestions persist, the negative effects will add up and result in poor overall performance, negative customer satisfaction, and ultimately a shuttered business.

Signs of a network congestion

Some signs that can alert administrators to network congestions include:

  • Slow network connectivity – especially if it is sudden and unanticipated.
  • Delays or jitters in data packet relays – especially within a limited environment that shouldn’t be acting so.
  • Dropped packets that should have otherwise been delivered without a hitch.
  • Loss of communication between applications, devices, and servers when there is no reason to be so.

In case of an issue, the loudest complaints will almost always come from users and customers. That is why there needs to be a system in place to take notice of any early grumbles about the deterioration of a network or application’s response times.

How can network congestions be prevented?

Network administrators can implement two strategies to prevent a total collapse of their network: Network congestion control and Network congestion avoidance.

Network congestion control strategies involve:

  • Modulation – controlling incoming traffic from overwhelming a network by reducing packet rates.
  • Flow control – preventing origin devices from overwhelming destination devices when communicating with one another.

Network congestion avoidance strategies involve:

  • Watching for packet losses or delays in queues and adjusting a network’s packet transmission rates.
  • Managing data queues by rearranging packets by priority or even dropping them – temporarily or permanently – if they are deemed unnecessary.

These two strategies involve tactics that like:

  • Monitoring data packages that are on the network
  • Implementing a UAC (User Access Control) system that is always on top of accounts, roles, and privileges
  • Denying access to unauthorized users and devices
  • Removing legacy and defunct devices and replacing them with more modern and efficient ones

Using network performance monitoring tools

The good news here is that there are great network monitoring and administration tools on the market that can help keep an eye on networks and alert admins whenever there are issues or any suspicious activities.

These tools are also known as Quality of Service (QoS) tools because they make sure the network offers quality service by:

  • Prioritizing the packets to ensure sensitive and time-critical data does not get lost or dropped.
  • Monitoring network usage – or abuse – to look out for any issues that may cause congestion.
  • Alerting administrators if any thresholds have been surpassed or milestones are not met.
  • Auditing and reporting on activities to help with troubleshooting as well as trend analysis for forecasting.

We will have a detailed look at each one, but here’s a brief list of the best network monitoring tools admins can use to prevent network congestion:

  1. SolarWinds NetFlow Traffic Analyzer EDITOR’S CHOICE A product from the leader in the network monitoring and administration tools field, it gives real-time updates of the health of a network and integrates with other powerful products in the networking field to ensure deep, informative insights.
  2. ManageEngine NetFlow Analyzer (FREE TRIAL) A popular tool that is ideal for complex networking environments and can be used to ensure QoS policies are in place and being applied appropriately. Get a 30-day free trial.
  3. Site 24×7 Cloud Network Monitoring Software (FREE TRIAL) This would be the ideal choice for cloud networks and administrators who can monitor their infrastructure remotely with the help of numerous free tools. Start a 30-day free trial.
  4. Paessler PRTG Network Monitoring (FREE TRIAL) Apart from the network, this tool also includes monitoring of databases to control their impact on communication performance. Highly customizable maps show the network in a more comprehensible format. Start a 30-day free trial.
  5. Datadog Network Monitoring Another SaaS tool, it has a light footprint and is easy to implement and use. Scaling up is easy and it uses AI for smarter analysis.

Network congestion monitoring tools

Our methodology for selecting traffic management systems

We reviewed the market for network traffic analyzers and assessed the options based on the following criteria:

  • Extraction of traffic data from routers
  • The ability to communicate with NetFlow, sFlow, J-Flow, NetStream, and IP-FIX
  • Cisco NBAR for application traffic assessment
  • IP SLA, Mean Opinion Score, and Quality of Service measurements for VoIP traffic
  • Assistance in implementing traffic shaping
  • A free trial or a demo for an opportunity to check out the system before buying
  • Value for money from a network traffic analyzer that can also help improve congestion problems

1. SolarWinds NetFlow Traffic Analyzer (FREE TRIAL)

SolarWinds Website Header

SolarWinds is one of the best in the network and hardware management and monitoring tools industry – proof lies in SolarWinds NetFlow Traffic Analyzer.

Key Features:

  • NetFlow, J-Flow, sFlow, NetStream, and IPFIX
  • NBAR2 application recognition
  • Class-based Quality of Service
  • IP SLA Manager
  • Stack layer correlation

Why do we recommend it?

SolarWinds NetFlow Traffic Analyzer extracts traffic data from each network device. As each interface on each device has a finite capacity, tracking utilization will identify when a particular link is overloaded. Combining this service with the Network Performance Monitor’s network map to assist capacity planning and traffic shaping measures.

The main purpose of NetFlow Traffic Analyzer (NTA) is to collect traffic data, correlate it into a consumable format, and present it to admins in web-based dashboards and reports for further handling.

These highly-informative dashboards help to quickly identify and tackle root causes of issues; simply dragging-and-dropping network performance metrics into a common timeline results in immediate visual correlations across all network data and NetFlow analytics.

SolarWinds network map

Also, the tool can help admins review their historical data to identify things like peak bandwidth usage times which, in turn, helps them develop future scaling strategies.

As a matter of fact, the tool tracks both IPv4 and IPv6 packet flow records and works with other popular network flow monitoring tools – like Cisco NetFlow, Juniper J-Flow, sFlow, Huawei NetStream, and IPFIX flow – to help identify applications and protocols that consume too much bandwidth.

It spots any unusual changes in application traffic patterns and alerts admins in case of device failure to send data packets; the tool can even work in the virtual realm – it can give insights into flow data from VMware vSphere switches.

In fact, NTA performs tasks like filtering out east-west traffic on specific VMMs (Virtual Machine Monitors).

Admins can gain deeper insight into HTTP and HTTPS traffic – the corresponding protocols for the unsecured (port 80) and secured (port443) data traffic, respectively – without the need for additional tools.

This tool has the ability to monitor and analyze Wireless LAN Controller (WLC) traffic to keep track of mobile and portable devices and their wireless bandwidth consumption which is then presented in customizable network traffic reports.

More importantly, businesses that have VoIP, e-commerce, or cloud-based applications running on their networks can use this tool to organize and prioritize their data packets to achieve QoS policy optimization.

Finally, SolarWinds NetFlow Traffic Analyzer integrates well with their network User Device Tracker which provides user contact info and switch port location – allowing admins to contact their users to ask them to reduce their bandwidth usage or kick them off the network if they don’t comply.

Who is it recommended for?

This system is suitable for mid-sized and large organizations. The NetFlow Traffic Analyzer requires the presence of the Network Performance Monitor, both of which can be bought together in the Network Bandwidth Analyzer Pack. This bundle provides live status monitoring of network devices and traffic data extraction plus troubleshooting tools.


  • Supports multiple protocols great for monitoring Cisco equipment and other popular infrastructure vendors
  • Both tools work well alongside each other to help view traffic patterns and bandwidth usage
  • Easy-to-use interface automatically highlights bandwidth hogs and other network traffic outliers
  • Scales well, designed for large enterprise networks
  • Can view traffic on a per-hop basis, allowing for granular traffic analysis


  • Built for enterprise use, not designed for small home networks

Download a 30-day fully-functional Free Trial of SolarWinds NetFlow Traffic Analyzer.


SolarWinds NetFlow Traffic Analyzer is our top pick for a network congestion troubleshooting tool because it enables analysis of all types of traffic and lets you decide how you can get the best value out of your existing network infrastructure and avoid the expense of buying in more capacity. With this tool, you can identify which applications need to be prioritized and then implement queuing on network devices in order to give interactive applications, such as VoIP, priority. This system helps you to identify bottlenecks on your network and reroute traffic to relieve that choke point.

Official Site:

OS: Windows Server

2. ManageEngine NetFlow Analyzer (FREE TRIAL)

ManageEngine Website Header
ManageEngine NetFlow Analyzer, a network monitoring tool that is popular among administrators of complex networking environments.

Key Features:

  • Bottleneck identification
  • VoIP performance tracking
  • Traffic shaping tools
  • Class-based Quality of Service

Why do we recommend it?

ManageEngine NetFlow Analyzer is a similar product to the SolarWinds NetFlow Traffic Analyzer. Both are delivered as a software bundle and both extract traffic data from switches using the NetFlow protocol and adaptations of that system, such as sFlow and J-Flow. Use this package to detect traffic bottlenecks and implement traffic shaping.

It has real-time reports and graphs that give a comprehensive insight into network traffic, the top applications running on a network. This ensures mission-critical processes run as expected –and a customizable dashboard that shows all relevant traffic information in one place.

The tool also has capacity planning reports for trend analysis and forecasting requirements.

It has Class-Based Quality of Service (CBQoS) reports ensuring that QoS policies are being enforced effectively and allow admins to easily prioritize their network traffic as they may see fit.

ManageEngine NetFlow Analyzer dashboard

NetFlow Analyzer monitors WLCs for statistics on bandwidth which can also be used in reports with drill-down capabilities for in-depth information on WLAN, SSIDS, APs (Access Points), and QoS.

There are numerous add-ons and plugins that help with tasks like monitoring of critical factors that can affect VoIP and video quality, and WAN Round Trip Time (RTT) monitoring to ensure seamless WAN connectivity.

It can be used to stop bandwidth hogging by reconfiguring policies with traffic-shaping techniques.

The tool works seamlessly with routers and switches to monitor network traffic, WAN link availability, latency, and overall performance to keep an eye on the network as a whole. It can even view just segments in case more detailed information is required about a particular department’s network consumption, for example.

Who is it recommended for?

This tool is suitable for use by mid-sized and large organizations. There is a Free edition available, but that will only monitor two interfaces. The lowest capacity available with the Professional edition is for 10 interfaces and the lower Standard plan would be cheaper, except that the minimum capacity is for 500 interfaces.


  • Both tools work well alongside each other monitors to help view traffic patterns and bandwidth usage
  • Easy-to-use interface automatically highlights bandwidth hogs and other network traffic outliers
  • Scale well, designed for large enterprise networks
  • Can view traffic on a per-hop basis, allowing for granular traffic analysis


  • Built for enterprise use, not designed for small home networks

Download a 30-day Free Trial of ManageEngine NetFlow Analyzer.

ManageEngine NetFlow Analyzer Start a 30-day FREE Trial

3. Site24x7 Cloud Network Monitoring Software (FREE TRIAL)

Site 24x7 Website Header

Site24x7 is a cloud-based monitoring service that offers end-to-end monitoring including a Network Monitor with impressive network supervising capabilities and checks for bottlenecks or overloads.

Key Features:

  • Monitors routers and switches
  • Tests LANs, internet connections, and wireless systems
  • VoIP monitoring

Why do we recommend it?

Site24x7 Network Monitoring is part of a cloud platform of system monitoring services. This bundle includes both network device monitoring and bandwidth analysis services. The system can extract flow metrics from switches and it also provides tools for troubleshooting. As well as observing network traffic, this package can measure the performance of internet connection between sites and to cloud platforms.

To begin with, the network monitoring tool keeps an eye on almost all connectivity devices: firewalls, VPNs, printers, and even UPS’.

It, in fact, monitors routers and switches to spot spikes, and bottlenecks and looks out for suspicious activities.

Also, it visualizes the connection and devices’ health with the help of interactive maps and dashboards which allows for complete insight into a network.

Being a SaaS, administrators don’t even need to be onsite; they can monitor their network uptimes using mobile devices or remotely manage multiple networks from a single cloud platform.

Automated or unattended monitoring can be done with the On-Premises Poller – which collects data according to set poll intervals – which sends information back to a data collector that can then be further used as input for reports.

This also means alerts can be sent to administrators located anywhere via SMS, emails, and even voice calls.

The On-Premises Poller – which can be configured to monitor a single IP address or a range of them (up to a whole network) – can also notify admins about downtime within a minute of a monitored device going down.

Site 24x7 On-Premises Poller architecture

Other metrics that can be monitored include: undersized or oversized packets, dropped packets, jabber packets, VPN latency, Interface collisions, and much more.

There are real-time reports and status updates for all nodes and devices and even a Network Operations Center (NOC) view to help with coordinated troubleshooting.

Site24x7 interfaces NOC view

Admins can drill down on key metrics like response times or packet losses, for example, and combine them with a certain device to get deeper insights that help understand the current overall status of the device. They can identify issues before they happen, and even allow for future forecasting based on current trends.

Who is it recommended for?

This system is suitable for businesses of all sizes. Site24x7 offers plans that include all of the modules on the platform, rather than charging separately for each module. Thus, you get server and application monitoring in with your network traffic analysis system. Plans are priced according to capacity with the smallest options suitable for small businesses.


  • Features a mobile app for both Android and iOS
  • Can measure can detect latency, jitter, and performance over time, making it a viable long-term solution for ping monitoring
  • Can integrate and monitor up to 200 different vendor devices
  • The free version can support up to hosts, making it a great introductory option for smaller businesses


  • Site24x7 is a feature-dense platform that can take time to fully learn all of its features and customization options

Finally, Site24x7 offers other free tools that can help administrators with managing their networks including a subnet calculator (IPv4 and IPv6), random password generator, blacklist checker, and more. Download a 30-day Free trial of Site24x7 Network Monitoring Software.

Site24x7 Network Monitoring Software Start a 30-day FREE Trial

4. Paessler PRTG Network Monitor (FREE TRIAL)

Paessler Website Header

Paessler also makes products that cover IT infrastructures from end to end, and its PRTG Network Monitor tool monitors all the devices, systems, and traffic on a network.

Key Features:

  • NetFlow, J-Flow, sFlow, and IPFIX
  • QoS, CBQoS, and IP SLA
  • Connection quality tests

Why do we recommend it?

Paessler PRTG Network Monitor is a large package of sensors that include many network traffic analysis features, which include flow metric gathering sensors for NetFlow, IPFIX, and sFlow, among others. The tool is able to identify overloaded switches and can also measure the quality of connections.

It monitors bandwidth to see how much resource is being used by applications and devices while also keeping a close eye on the datasets from databases to see how they cope with traffic and data access during read/write sessions; this helps spot delays and overloads with the databases themselves or the platforms they sit on.

Databases that can be monitored include MySQL, Microsoft SQL v2, Oracle SQL v2, and PostgreSQL. Admins can also use the generic ADO SQL v2 Sensor or even create their own customized sensors if all else fails.

The tool manages applications to analyze their efficiency when sending data packets on the network during inter-device communication or while executing data queries.

It centrally monitors all assets in the cloud as well as those located locally on a LAN – it can in fact cover a diverse number of devices via SNMP.

Paessler Network Monitor dashboard

The highly customizable real-time maps with live status information can be viewed from customizable dashboards with the PRTG Map Designer. It can integrate all network components using more than 300 different map objects such as device and status icons, traffic charts, top lists, and lots more.

Admins can truly customize these maps using custom HTML. Once done, they can then share their maps as a URL that can be accessed either publicly or only internally on their LAN.

Who is it recommended for?

This service is suitable for any business because it is so adaptable. The software package runs on Windows Server. However, if you don’t have that operating system on-site, you can opt for the SaaS version. Buyers pay for an allowance of sensors and then choose which of the monitoring systems to activate.


  • Designed to be an infrastructure monitoring tool that supports multiple sensor types such as NetFlow, sFlow, and J-Flow
  • Offers additional monitoring on the same platform, supporting infrastructure, network, and application performance monitoring
  • Captures packet headers only, helps speed up analysis and keep storage costs down for long-term collection
  • Uses simple yet intuitive graphing for traffic visualization


  • Very detailed platform that takes time to learn and fully utilize all of the features available

Directly download the Free Unlimited Version of PRTG Network Monitor for 30 days. After 30 days, PRTG reverts to a free version.

Paessler PRTG Network Monitor Start a 30-day FREE Trial

5. Datadog Network Monitoring Tool

Datadog Website Header

Datadog is another company that offers a Network Monitoring Tool as SaaS. This Datadog network performance monitoring tool keeps an eye on networks that are located on-site, remotely, in the cloud, or even a hybrid one that utilizes all of these architectures.

Key Features:

  • Monitors LANs, internet, and cloud
  • Queries network devices
  • Tracks virtual systems

Why do we recommend it?

Datadog Network Monitoring is implemented in two modules. The first of these is the Network Device Monitoring service, which uses SNMP to check on the statuses of system hardware. The second is the Network Performance Monitoring service and it is this package that you will need in order to monitor networks for congestion and troubleshoot for solutions.

Apart from the network, the tool also monitors apps, services, and devices that use the connection; this means, the Network Monitoring tool consolidates the data garnered from monitoring the network with information collected from other inputs to paint a full picture.

If administrators need even more in-depth information, the tool can be extended further with APIs.

Being a SaaS tool makes it easy to install because all that is required is to deploy an Agent that is available for all major operating systems including Windows, macOS, Linux, and Docker.

The Agent also means the tool has a light digital footprint and won’t affect the network’s performance. It also has its own storage to keep the collected data, and scalability is a breeze that won’t waste time or require great technical know-how.

The browser-based interface makes it easy and convenient to use, but it is also pretty straightforward to master the dashboard – which is not only aesthetically pleasing but also highly informative – that comes with features like drill-down reports in real-time and traffic flow monitoring that displays the results in graphs that are highly customizable.

DataDog Network Map

Datadog uses AI Machine Learning to allow the tool to forecast future trends based on the analysis of current data.

Who is it recommended for?

This is an affordable solution but, unlike the Site24x7 service, you have to choose modules from a list and pay for each in order to assemble a system monitoring package. The Network Performance Monitor works well with the Network Device Monitor and both of these modules rely on the presence of the Infrastructure Monitoring plan for network discovery.


  • Offers advanced troubleshooting features and root cause analysis to help reduce TTR
  • Cloud-based SaaS product allows monitoring with no server deployments or onboarding costs
  • Can monitor both internally and externally giving network admins a holistic view of network performance and accessibility
  • Supports auto-discovery that builds network topology maps on the fly
  • Changes made to the network are reflected in near real-time
  • Allows businesses to scale their monitoring efforts reliably through flexible pricing options


  • Would like to see a longer trial period for testing

Download a 14-day Free Trial of Datadog Network Monitoring Tool.

Using network monitoring tools against network congestion

Ok, now that we have seen the best network monitoring tools, let’s see what we can use them for when trying to avoid network congestion:

  • Keep track of the traffic to see what is passing in the network and decide whether it belongs there or not.
  • Use the tools to isolate rogue users, applications, services, and devices.
  • Use Net Flow to track packet attributes like time taken, timeouts, and dropped packets and use them as metrics to gauge the networks’ performances using reports and graphs.
  • Auto-monitor networks around the clock and set milestones or benchmarks for alerts.
  • Keep an eye on said alerts and respond to them ASAP.
  • Use maps to make sure the network topography is as it should be and that all packets are flowing – in to, out of, and across various architectures – without issues.

Tackling these tasks will ensure no network congestion cripples a business’s processes and prevent any causative issues from occurring in the first place.

We would like to know of any network monitoring tools you have used; leave us a comment below.