Measuring network quality to better understand the end-user experience

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You’re visiting your family for the holidays and you connect to the WiFi, and then notice Netflix isn’t loading as fast as it normally does. You go to speed.cloudflare.com, fast.com, speedtest.net, or type “speed test” into Google Chrome to figure out if there is a problem with your Internet connection, and get something that looks like this:

If you want to see what that looks like for you, try it yourself here. But what do those numbers mean? How do those numbers relate to whether or not your Netflix isn’t loading or any of the other common use cases: playing games or audio/video chat with your friends and loved ones? Even network engineers find that speed tests are difficult to relate to the user experience of… using the Internet.

Amazingly, speed tests have barely changed in nearly two decades, even though the way we use the Internet has changed a lot. With so many more people on the Internet, the gaps between speed tests and the user’s experience of network quality are growing. The problem is so important that the Internet’s standards organization is paying attention, too.

From a high-level, there are three grand network test challenges:

1. Finding ways to efficiently and accurately measure network quality, and convey to end-users if and how the quality affects their experience.
2. When a problem is found, figuring out where the problem exists, be it the wireless connection, or one many cables and machines that make up the Internet.
3. Understanding a single user’s test results in context of their neighbors’, or archiving the results to, for example, compare neighborhoods or know if the network is getting better or worse.

Cloudflare is excited to announce a new Aggregated Internet Measurement (AIM) initiative to help address all three challenges. AIM is a new and open format for displaying Internet quality in a way that makes sense to end users of the Internet, around use cases that demand specific types of Internet performance while still retaining all of the network data engineers need to troubleshoot problems on the Internet. We’re excited to partner with Measurement Lab on this project and store all of this data in a publicly available repository that you can access to analyze the data behind the scores you see on your speed test page, whose source code is now open-sourced along with the AIM score calculations.

What is a speed test?

A speed test is a point-in-time measurement of your Internet connection. When you connect to any speed test, it typically tries to fetch a large file (important for video streaming), performs a packet loss test (important for gaming), measures jitter (important for video/VoIP calls), and latency (important for all Internet use cases). The goal of this test is to measure your Internet connection’s ability to perform basic tasks.

There are some challenges with this approach that start with a simple observation: At the “network-layer” of the Internet that moves data and packets around, there are three and only three measures that can be directly observed. They are,

• available bandwidth, sometimes known as “throughput”;
• packet loss, which occurs at extremely low levels throughout the Internet at steady state; and
• latency, often referred to as the round-trip time (RTT).

These three attributes are tightly interwoven. In particular, the portion of available bandwidth that a user actually achieves (throughput) is directly affected by loss and latency. Your computer uses loss and latency to decide when to send a packet, or not. Some loss and latency is expected, even needed! Too much of either, and bandwidth starts to fall.

These are simple numbers, but their relationship is far from simple. Think about all the ways to add two numbers to equal as much as one-hundred, x + y ≤ 100. If x and y are just right, then they add to one hundred. However, there are many combinations of x and y that do. Worse is that if either x or y or both are a little wrong, then they add to less than one-hundred. In this example, x and y are loss and latency, and 100 is the available bandwidth.

There are other forces at work, too, and these numbers do not tell the whole story. But they are the only numbers that are directly observable. Their meaning and the reasons they matter for diagnosis are important, so let’s discuss each one of those in order and how Aggregated Internet Measurement tries to solve each of these.

What do the numbers in a speed test mean?

Most speed tests will run and produce the numbers you saw above: bandwidth, latency, jitter, and packet loss. Let’s break down each of these numbers one by one to explain what they mean:

Bandwidth

Bandwidth is the maximum throughput/capacity over a communication link. The common analogy used to define bandwidth is if your Internet connection is a highway, bandwidth is how many lanes the highway has and cars that fit on it. Bandwidth has often been called “speed” in the past because Internet Service Providers (ISPs) measure speed as the amount of time it takes to download a large file, and having more bandwidth on your connection can make that happen faster.

Packet loss

Packet loss is exactly what it sounds like: some packets are sent from a source to a destination, but the packets are not received by the destination. This can be very impactful for many applications, because if information is lost in transit en route to the receiver, it an e ifiult fr te recvr t udrsnd wt s bng snt (it can be difficult for the receiver to understand what is being sent).

Latency

Latency is the time it takes for a packet/message to travel from point A to point B. At its core, the Internet is composed of computers sending signals in the form of electrical signals or beams of light over cables to other computers. Latency has generally been defined as the time it takes for that electrical signal to go from one computer to another over a cable or fiber. Therefore, it follows that one way to reduce latency is to shrink the distance the signals need to travel to reach their destination.

There is a distinction in latency between idle latency and latency under load. This is because there are queues at routers and switches that store data packets when they arrive faster than they can be transmitted. Queuing is normal, by design, and keeps data flowing correctly. However, if the queues are too big, or when other applications behave very differently from yours, the connection can feel slower than it actually is. This event is called bufferbloat.

In our AIM test we look at idle latency to show you what your latency could be, but we also collect loaded latency, which is a better reflection of what your latency is during your day-to-day Internet experience.

Jitter

Jitter is a special way of measuring latency. It is the variance in latency on your Internet connection. If jitter is high, it may take longer for some packets to arrive, which can impact Internet scenarios that require content to be delivered in real time, such as voice communication.

A good way to think about jitter is to think about a commute to work along some route or path. Latency, alone, asks “how far am I from the destination measured in time?” For example, the average journey on a train is 40 minutes. Instead of journey time, jitter asks, “how consistent is my travel time?” Thinking about the commute, a jitter of zero means the train always takes 40 minutes. However, if the jitter is 15 then, well, the commute becomes a lot more challenging because it could take anywhere from 25 to 55 minutes.

But even if we understand these numbers, for all that they might tell us what is happening, they are unable to tell us where something is happening.

Is WiFi or my Internet connection the problem?

When you run a speed test, you’re not just connecting to your ISP, you’re also connecting to your local network which connects to your ISP. And your local network may have problems of its own. Take a speed test that has high packet loss and jitter: that generally means something on the network could be dropping packets. Normally, you would call your ISP, who will often say something like “get closer to your WiFi access point or get an extender”.

This is important — WiFi uses radio waves to transmit information, and materials like brick, plaster, and concrete can interfere with the signal and make it weaker the farther away you get from your access point. Mesh WiFi appliances like Nest WiFi and Eero periodically take speed tests from their main access point specifically to help detect issues like this. So having potential quick solutions for problems like high packet loss and jitter and giving that to users up front can help users better ascertain if the problem is related to their wireless connection setup.

While this is true for most issues that we see on the Internet, it often helps if network operators are able to look at this data in aggregate in addition to simply telling users to get closer to their access points. If your speed test went to a place where your network operator could see it and others in your area, network engineers may be able to proactively detect issues before users report them. This not only helps users, it helps network providers as well, because fielding calls and sending out technicians for issues due to user configuration are expensive in addition to being time consuming.

This is one of the goals of AIM: to help solve the problem before anyone picks up a phone. End users can get a series of tips that will help them understand what their Internet connection can and can’t do and how they can improve it in an easy-to-read format, and network operators can get all the data they need to detect last mile issues before anyone picks up a phone, saving time and money. Let’s talk about how that can work with a real example.

An example from a real life

When you get a speed test result, the numbers you get can be confusing. This is because you may not understand how those numbers combine to impact your Internet experience. Let’s talk about a real life example and how that impacts you.

Say you work in a building with four offices and a main area that looks like this:

You have to make video calls to her clients all day and you sit in the office farthest away from the wireless access point. Your calls are dropping constantly and you’re having a really bad experience. When you runs a speed test from her office, she sees this result:

How can you make sense of these? A network engineer would take a look at the high jitter and the packet loss and think “well this user probably needs to move closer to the router to get a better signal”. But you may take a look at these results and have no idea, and have to ask a network engineer for help, which could lead to a call to your ISP, wasting the time and money of everyone. But you shouldn’t have to consult a network engineer to figure out if you need to move your WiFi access point, or if your ISP isn’t giving her a good experience.

Aggregated Internet Measurement assigns qualitative assessments to the numbers on your speed test to help you make sense of these numbers. We’ve created scenario-specific scores, which is a singular qualitative value that is calculated on a scenario level: we calculate different quality scores based on what you’re trying to do. To start, we’ve created three AIM scores: Streaming, Gaming, and WebChat/RTC. Those scores weigh each metric differently based on what Internet conditions are required for the application to run successfully.

The AIM scoring rubric assigns point values to your connection based on the tests. We’re releasing AIM with a “weighted score,” in which the point values are calculated based on what metrics matter the most in those scenarios. These point scores aren’t designed to be static, but to evolve based on what application developers, network operators, and the Internet community discover about how different performance characteristics affect application experience for each scenario – and it’s one more reason to post the data to M-Lab, so that the community can help design and converge on good scoring mechanisms.

Here is the full rubric and each of the point values associated with the metrics today:

And here’s a quick overview of what values matter and how we calculate scores for each scenario:

• Streaming: download bandwidth + unloaded latency + packet loss + (loaded latency - unloaded latency difference)
• Gaming: packet loss + unloaded latency + (loaded latency - unloaded latency difference)
• RTC/video: packet loss + jitter + unloaded latency + (loaded latency - unloaded latency difference)

To calculate each score, we take the point values from your speed test and calculate that out of the total possible points for that scenario. So based on the result, we can give your Internet connection a judgment for each scenario: Bad, Poor, Average, Good, and Great. For example, for Video calls, packet loss, jitter, unloaded latency, and the difference between loaded and unloaded latency matter when determining whether or not your Internet quality is good for video calls. We add together the point values derived from your speed test values and we get a score that shows how far away from the perfect video call experience your Internet quality is. Based on your speed test, here are the AIM scores from your office far away from the access point:

So instead of saying “Your bandwidth is X and your jitter is Y”, we can say “Your Internet is okay for Netflix, but poor for gaming, and only average for Zoom”. In this case, moving the WiFi access point to a more centralized location turned out to be the solution, and turned your AIM scores into this:

You can even see these results on the Cloudflare speed test today as a Network Quality Score:

In this particular case, there was no call required to the ISP, and no network engineers were consulted. Simply moving the access point closer to the middle of the office improved the experience for everyone, and no one needed to pick up the phone, providing a more seamless experience for everyone.

AIM takes the metrics that network engineers care about and it translates them into a more human-readable metric that’s based on the applications you are trying to use. Aggregated data is anonymous (in compliance with our privacy policy), so that your ISP can actually look up speed tests in your metro area and that use your ISP and get the underlying data to help translate user complaints into something that is actionable by network engineers. Additionally, policy makers and researchers can examine the aggregate data to better understand what users in their communities are experiencing to help lobby for better Internet quality.

Working conditions

Here’s an interesting question: When you run a speed test, where are you connecting to and what is the Internet like at the other end of the connection? One of the challenges that speed tests often face is that the servers you run your test against are not the same servers that run or protect your websites. Because of this, the network paths your speed test may take to the host on the other side may be vastly different, and may even be optimized to serve as many speed tests as possible. This means that your speed test is not actually testing the path that your traffic normally takes when it’s reaching the applications you normally use. The tests that you ran are measuring a network path, but it’s not the network path you use on a regular basis.

Speed tests should be run under real-world network conditions that reflect how people use the Internet, with multiple applications, browser tabs, and devices all competing for connectivity. This concept of measuring your Internet connection using application-facing tools and doing so while your network is being used as much as possible is called measuring under working conditions. Today, when speed tests run, they make entirely new connections to a website that is reserved for testing network performance. Unfortunately, day-to-day Internet usage isn’t done on new connections to dedicated speed test websites. This is actually by design for many Internet applications, which rely on reusing the same connection to a website to provide a better performing experience to the end-user by eliminating costly latency incurred by establishing encryption, exchanging of certificates, and more.

AIM is helping to solve this problem in several ways. The first is that we’ve implemented all of our tests the same way our applications would, and measure them under working conditions. We measure loaded latency to show you how your Internet connection behaves when you’re actually using it. You can see it on the speed test today:

The second is that we are collecting speed test results against endpoints that you use today. By measuring speed tests against Cloudflare and other sites, we are showing end user Internet quality against networks that are frequently used in your daily life, which gives a better idea of what actual working conditions are.

AIM database

We’re excited to announce that AIM data is publicly available today through a partnership with Measurement Lab (M-Lab), and end-users and network engineers alike can parse through network quality data across a variety of networks. M-Lab and Cloudflare will both be calculating AIM scores derived from their speed tests and putting them into a shared database so end-users and network operators alike can see Internet quality from as many points as possible across a multitude of different speed tests.

For just a sample of what we’re seeing, let’s take a look at a visual we’ve made using this data plotting scores from only Cloudflare data per scenario in Tokyo, Japan for the first week of October:

Based on this, you can see that out of the 5,814 speed tests run, 50.7% of those users had a good streaming quality, but 48.2% were only average. Gaming appears to be relatively hard in Tokyo as 39% of users had a poor gaming experience, but most users had a pretty average-to-decent RTC experience. Let’s take a look at how that compares to some of the other cities we see:

Based on our data, we can see that most users do okay for video streaming except for Mumbai, which is a bit behind. Users generally have a variable gaming experience due to high latency being the primary driver behind the gaming score, but their RTC apps do slightly better, being generally average in all the locales.

Collaboration with M-Lab

M-Lab is an open, Internet measurement repository whose mission is to measure the Internet, save the data, and make it universally accessible and useful. In addition to providing free and open access to the AIM data for network operators, M-Lab will also be giving policy makers, academic researchers, journalists, digital inclusion advocates, and anyone who is interested access to the data they need to make important decisions that can help improve the Internet.

In addition to already being an established name in open sharing of Internet quality data to policy makers and academics, M-Lab already provides a “speed” test called Network Diagnostic Test (NDT) that is the same speed test you run when you type “speed test” into Google. By partnering with M-Lab, we are getting Aggregated Internet Measurement metrics from many more users. We want to partner with other speed tests as well to get the complete picture of how Internet quality is mapped across the world for as many users as possible. If you measure Internet performance today, we want you to join us to help show users what their Internet is really good for.

Speed test, now open sourced

In addition to partnering with M-Lab, we’ve also open-sourced our speed test client. Open-sourcing the speed test is an important step towards giving applications access to speed measurements through Cloudflare, and an easy way to start calculating AIM scores for your application. Our speed test is now embeddable as a javascript application so that you can perform network quality tests without needing to navigate to the browser. The application not only provides you all of the measurements we use for our speed test today, but also uploads the results in a private fashion to Cloudflare. The repository also shows how we are calculating the AIM scores, so that you can see the inner workings of how network quality is being defined to end-users and how that changes in real-time. To get started developing with our open-source speed test, check out the open-source link.

A bright future for Internet quality

We’re excited to put this data together to show Internet quality across a variety of tests and networks. We’re going to be analyzing this data and improving our scoring system, and we’ve open-sourced it so that you can see how we are using speed test measurements to score Internet quality across a variety of different applications and even implement AIM yourself. We’ve also put our AIM scores in the speed test alongside all of the tests you see today so that you can finally get a better understanding of what your Internet is good for.

If you’re running a speed test today and you’re interested in partnering with us to help gather data on how users experience Internet quality, reach out to us and let’s work together to help make the Internet better. And if you’re running an application that wants to measure Internet quality, check out our open source repo so that you can start developing today.

Figuring out what your Internet is good for shouldn’t require you to become a networking expert; that’s what we’re here for. With AIM and our collaborators at MLab, we want to be able to tell you what your Internet can do and use that information to help make the Internet better for everyone.