Packet loss: What it is and what causes it

Packet loss is an invisible online connectivity issue that can impact your online experience. Here’s what it is and how to manage it.

The convenience of a connected home can sometimes be offset by certain connectivity hurdles that have the potential to negatively affect your experience.

‘Packet loss’ is a connectivity issue that can impact web surfing, file transfers, voice over internet protocol (VoIP) calls, video/audio streaming, and online gaming.

Let’s shine a light on this often-invisible connectivity woe.

What is packet loss?

First, let’s break down the term.

The first part, ‘packet’, is technical shorthand for ‘data packet’.

Regardless of what you’re doing on the internet, consistent online connectivity is reliant on your home network’s ability to send and receive data packets.

The second part of the term, ‘loss’, is more straightforward.

It refers to an instance where one or more data packets fail to reach its or their intended destination.

Certain applications tend to be built with packet loss in mind, which means you may never notice if a low number of packets are dropped, as they’re seamlessly re-requested and retransmitted.

In other online scenarios, packet loss can result in a reduced experience.

For instance, online gaming and file transfers are dependent on zero packet loss for a smooth (gaming) or complete (file transfer) experience.

What packet loss looks like

The effect of packet loss may be different depending on what you’re doing online.

If you’re surfing the web, a single lost (or ‘dropped’) data packet may result in a webpage not opening on an initial website-visit attempt.

In terms of file transfer or downloading, the transferred file may become corrupted.

For videoconferencing, packet loss can result in a noticeable jitter (audio and/or video oddities).

The same is true of steaming audio or video – locally or online  – in that packet loss may result in audio or video jitters similar to videoconferencing.

It’s much the same with VOIP calls, where packet loss may result in skipped or distorted audio transmission.

In terms of online gaming, packet loss can lead to freezes in real-time gameplay, disconnections to game servers, or inconsistencies in player control-input registry.

Local network packet loss

There are several factors that might lead to packet loss, either on your local home network or the external online network.

Wi-fi can lead to packet loss if the total wireless bandwidth of your home network is in use, but with modern routers this is unlikely.

The same is also true of Ethernet connections, or home networks with a mix of wi-fi and Ethernet (wired) connections, if the bandwidth capacity has been exhausted.

If the total local network bandwidth – determined by your modem/router – is in use, your modem/router may choose to dynamically deprioritise network traffic to a specific or multiple device/s, which may result in packet loss.

Local network packet loss can also be caused by outdated firmware on your modem/router or older networking drivers on connected devices.

Refer to the website of your devices to check on how to update these.

Online packet loss

In terms of external, online network connections, packet loss may be an unfortunate result of how the internet works.

Here’s how.

When connecting to any online destination, the data packets must first travel from device to your modem/router.

On the way to its destination, the packets then pass through your external IP address, past your retail service provider’s networking systems, and then jumps between servers (called ‘server hops’) on its way to where you want to go.

On a high-speed broadband connection, this process will likely happen in fractions of a second (latency issues notwithstanding).

But if there is packet loss at one of the server hops, data transmitted back to your device may be lost and arrive incomplete.

Testing for packet loss

You can use a computer to determine whether potential packet loss is occurring at a local network (modem/router) level, or whether it’s happening externally (online).

In terms of Windows devices, Microsoft has this article for explaining how to use a ‘traceroute’ test to determine whether potential packet loss is a local or external issue.

There are also steps for running traceroute on Mac OSX and Linux/Unix.

Though somewhat complicated, here’s what to bear in mind when running the test.

Let’s use a hypothetical example:

After running a traceroute test on our mystery connection, the first two IP addresses in the list of results refer to local network connections.

In this case, the first is your router and the second is your modem, even if your modem and router are bundled into the same modem/router device.

The third IP address result is your retail service provider.

The additional IP addresses between your retail service provider and your IP address are the previously-mentioned server hops.

Isolating packet loss

If you suspect packet loss is happening on your home connection, you’d start by running the traceroute test on the first local network IP addresses, before moving on to your retail service provider and the server hops.

Any time the traceroute test returns a ‘Request timed out’ result, this means the test experienced packet loss somewhere between your computer and the destination IP address.

If those ‘Request timed out’ messages come back on the first IP address, the issue is likely with your router (or modem/router).

If you receive the same message when traceroute testing the third IP address, you can contact your retail service provider to run external diagnostic tests on your connection.

If the ‘Request timed out’ messages occur at the server hop stage, unfortunately, that’s usually outside of your control, though it might be worth mentioning to your retail service provider.

Outside of running traceroute tests, packet loss may be outside of your control, short of ensuring you have adequate bandwidth on your local network and checking that your networking software/firmware is up to date.

At the very least, you can often identify where you might be dropping packets, and, if they do happen to be outside of your local private network, talk to your retail service provider about next steps.