Causes of Packet Loss & How to Mitigate Them

Packet loss can significantly hinder productivity and communication. Picture a busy highway during rush hour: too many cars trying to use the same lanes cause delays and accidents. Similarly, excessive data over a corporate network can lead to congestion, resulting in slowdowns and lost information packets. This can disrupt critical business activities, from video conferencing to cloud uploads.

Network congestion

Network congestion occurs when too much data is sent over a network at the same time. It’s the equivalent of too many cars trying to use the same road at the same time. That congestion causes a jam that slows all the traffic. 

Similarly, network congestion means data packets can get delayed or even dropped because the network nodes, like routers and switches, can't keep up.

When streaming videos, a congested internet connection will cause your video quality to drop, or the video may freeze while waiting for buffering. The service might downscale video quality to compensate for the packets that never made it to your device.

Another example is when you're uploading a large file to the cloud during peak internet usage times. You'll notice the upload takes too long and sometimes fails. Your ISP's network might be congested from everyone being online, so your packets get delayed or dropped altogether.

Faulty hardware

The tiniest issue with your devices can cause packet loss. Frayed or damaged cables can cause data to be corrupted as it travels. Replacing the cable will instantly fix the problem. 

Routers and switches can also malfunction, causing packet loss. They can have bad ports that mess up data transmission. Devices connected to that specific port will lose packets, while everything else works fine. Swapping to another port will fix the problem.

Another piece of hardware that may fail and cause packet loss is your network interface cards (NICs). A bad NIC can cause intermittent connectivity issues. Replacing the NIC will solve your packet loss issue.

Software bugs

Packet loss can often be traced back to software issues in the network stack. 

A bug in the firmware of a network switch, for example, can take you an entire weekend to uncover. 

It’s not just network hardware that is vulnerable to bugs. Application-level software can be just as vulnerable. For instance, a TCP/IP stack implementation in an operating system. 

A bug in the retransmission logic can lead to packets being dropped repeatedly, regardless of the network conditions. The packet loss may be down to a minor update that caused the TCP/IP stack to mismanage ACK packets.

Commercial software is also not immune to bugs. A bug in the deep packet inspection engine of a firewall application may incorrectly flag legitimate traffic as malicious, leading to a significant number of dropped packets. 

Wireless interference

Wireless interference can be a real pain when it comes to packet loss in networking. Video buffering is a common consequence of packet loss resulting from wireless interference.

A major source of wireless interference is other electronic devices. Microwave ovens and cordless phones can affect Wi-Fi signals. Another is overlapping Wi-Fi channels. When too many routers nearby use the same channel, they fight for airspace. 

Imagine being in a crowded room where everyone’s trying to talk over each other. No one can hear anything. That’s what happens with overlapping Wi-Fi channels. Even weather can play a role. Heavy rain, for instance, can degrade Wi-Fi performance. 

Physical obstructions can also interfere with your Wi-Fi signals. Walls, floors, and even large furniture can weaken Wi-Fi signals. You may need to install a Wi-Fi extender to get a signal strong enough to work from your basement. 

Network configurations

A network configuration is the arrangement and setup of network devices, protocols, and connections that make a network function. Think of it as the blueprint for how data flows from one point to another.

Configuring a router, for example, is more involved than simply plugging things in. You have to set up your router’s SSID, which is the name of your Wi-Fi network. It’s the name you see when you search for available networks on your devices.

Subnets also play a crucial role in network configurations. A subnet is a smaller network within a larger network. Subnetting helps in managing and optimizing the network. It also helps in prioritizing certain traffic. Therefore, prioritizing the wrong traffic may cause packet loss, meaning persistent interruptions during important team meetings.

Misconfiguring the firewall can also cause packet loss. A firewall acts as a security guard for your network, deciding what data gets in and what stays out. If you don’t assign your ports correctly, you will struggle to get your critical applications to work.

DNS (Domain Name System) is another aspect critical for managing packet loss. When you type a web address like `www.example.com`, DNS translates it into an IP address so your browser can load the website. Setting your router to use a reliable DNS service, like Google DNS or OpenDNS, can speed up your browsing experience.

Port forwarding, which redirects communication requests from one address and port number to another, is also prone to misconfiguration. While it is helpful for things like hosting a web server, it can be tricky to configure. You may have to forward a port on your router to your computer’s internal IP address.

Wireless network settings are another essential part of network configurations. Make sure to use encryption such as WPA3 to secure your Wi-Fi. If you leave your network open by mistake, unauthorized people may use up your bandwidth streaming videos and playing video games.

Detecting packet loss with network monitoring tools.

Wireshark

Wireshark is a powerful packet analyzer that you can use to capture packets in real-time and analyze the data to see precisely where packets are being lost. You can filter the captured data to look for specific types of packets, making it easier to spot issues.

PingPlotter

More user-friendly than Wireshark, PingPlotter is excellent for visualizing packet loss over time. It allows you to see which hops along a route are losing packets. It's helpful to pinpoint where the problem lies in your network path.

My Traceroute (MTR) 

MTR is a solid choice for those who prefer open-source tools. It combines the functionality of the traceroute and ping programs in a single network diagnostic tool. MTR provides continuous feedback about the route your packets take and how successful they are. It's less polished than PingPlotter but still quite effective.

Nagios

Nagios is an excellent network monitoring system that can alert you to packet loss. It is perfect if you're managing a large network. You set up various checks, and it notifies you if something goes wrong. Though it can be a bit complex to configure, it’s pretty powerful.

SolarWinds network performance monitor

SolarWinds is an enterprise solution that offers comprehensive monitoring capabilities and can give you valuable insights into packet loss. It's got a nice graphical interface and can integrate with other SolarWinds tools if you are already using them.

Ping

Ping is a basic network utility that can tell you a lot about the state of the network. By sending packets of data to a specific IP address and waiting for a response, ping helps you understand if the data is getting through and tells you how long it takes.

For example, if you notice users complaining about slow internet speeds or dropped connections, you can open up a terminal and type `ping google.com.` This command sends a series of ICMP Echo Request messages to Google’s servers. 

If everything works well, you will see lines of replies from Google, each showing the time it took for the round trip. This time is measured in milliseconds (ms).

However, if there's packet loss, you will see that some packets don't return. The terminal might show something like `Request timed out` or `Destination Host Unreachable,` indicating that some of those little packets you sent didn’t return. For example, if you send 10 packets and only 8 come back, that’s a 20% packet loss.

The ping tool also summarizes the number of packets sent, received, and lost, along with the minimum, maximum, and average trip time. This summary helps you get a quick snapshot of network performance. 

If you see that packet loss is present, know there's an issue that needs addressing, such as network congestion, faulty hardware, or even configuration issues.

Traceroute

Traceroute is like a roadmap for your data packets, showing the path they take to reach their destination. This is handy for identifying where packets might be getting lost.

When you run a traceroute command, it sends out a series of packets with increasing time-to-live (TTL) values. Each "hop" or router along the path decreases the TTL by one. When the TTL hits zero, the router sends back a message. This way, traceroute maps out the route, hop by hop, until it reaches the target server or hits a snag.

Say you're experiencing packet loss from your computer to a website like example.com. You would open your terminal or command prompt and type `traceroute example.com` on Unix-based systems or `tracert example.com` on Windows. Then, you’d see a series of lines, each representing a hop. Each line lists the hop number, the router IP, and the round-trip times for the packets.

Now, if you see asterisks (*) instead of times, it indicates a lost packet or that the router is not responding. For instance, if the output looks something like this:

Here, hops 2 and 5 show packet loss. Hop 2 may be ignoring ICMP requests, but hop 5 suggests there’s an issue.

When you see consistent packet loss at a specific hop, it’s usually a sign of trouble. If multiple hops show packet loss, it might mean network congestion or a broader issue affecting several routers.

How to mitigate packet loss

1. Keep your hardware firmware up to date.

Ensure network devices, like routers and switches, are running the latest firmware. Firmware updates often include fixes for bugs that could be causing packet loss. A router that frequently drops packets may have missed a firmware update.

2. Replace worn cables and old hardware.

Replacing old, worn-out Ethernet cables can reduce packet loss significantly. It's a good idea to regularly check all your cables and replace any that show signs of wear and tear.

3. Monitor your network traffic. 

Heavy traffic can overwhelm your network, leading to packet loss. Tools like Wireshark and PRTG Network Monitor can help you identify when and where traffic spikes occur. 

A significant increase in traffic during certain times of the day may point to an automated backup running during peak hours. Scheduling these backups for off-peak hours can dramatically improve network performance.

Quality of Service (QoS) settings on your routers and switches can also help. QoS prioritizes critical network traffic to ensure that essential data gets through even during high congestion. For example, you can prioritize VoIP traffic to avoid choppy audio on calls.

4. Change the Wi-Fi channel.

Changing the Wi-Fi channel or moving the router to a more central location can fix the wireless interference that may be slowing your Wi-Fi and causing packet loss. Moving your router just a few feet may result in a noticeable improvement in signal strength.