Apple's new 'Responsiveness' test in iOS 15 and macOS 12
UPDATE - Wi-Fi is hard…
Turns out the device I used to capture this traffic (wasn’t my nXG) just didn’t pick up on the data that was being transmitted…
Here’s a TCP dump courtesy of Kieran Roberts - turns out Apple is sending a bunch of data and it’s all heading to one of Apple’s CDNs.
So whilst it now isn’t only checking the WLAN (which is a shame as I liked the idea of just checking the internal network quality) it is probably a more useful test for developers, which is what it’s aimed at.
I’ve left the original post below (just for humility)
The Apple Network Responsiveness test measures the responsiveness of a network, or its ability to multitask when multiple devices and apps are sharing the network at the same time. But what is it actually doing?
You can read about it from Apple here
It seems like a great, repeatable metric to see what the ‘air quality is like for Wi-Fi. Whilst this isn’t going to replace the speedtest test for normal people this looks like it could be a helpful Airtime test for pros.
How to test responsiveness (on iOS / iPadOS)
You can run the Apple Network Responsiveness test on iOS, iPadOS, or macOS.
On your iOS or iPadOS device
Join the Wi-Fi network that you want to test.
Go to the Wi-Fi Profiles and Logs page on Apple's developer website. You might need to log in to your Apple Developer account.
Tap Profile to download the Wi-Fi profile. Open the Settings app, then tap Profile Downloaded. Tap Install to begin installing the "WiFi Performance Diagnostics" profile. Follow the on-screen instructions to finish installing the profile.
Once the profile is installed, go to Settings > Wi-Fi.
Tap the Info icon ‘i’ next to your network, then tap Diagnostics.
Next to Responsiveness, tap Test.
If you want to test it on your mac running the beta version of Monterey (everyone does that right?!?!) you can just type: “networkquality” (sans quote marks) into Terminal. You’ll get something like this…
So what does Apple tell us about this new test? Not much as you’d expect!
Under the test result, you get a small bit of information.
Responsiveness measures the quality of your network by the number of roundtrips completed per minute (RPM) under working conditions.
If you click ‘learn more’ you get the following:
About RPM
How does it affect me?
Responsiveness measures the quality of your network while it is actively being used. You can experience this in normal use cases when you are making a FaceTime call and you (or someone else on the same network) is transferring a large file or otherwise actively using the Internet connection. When responsiveness is slow, it means your network has a low ability to do multiple things at the same time. You might experience a slow network when others are actively using the same network as well. A high responsiveness means your network support serving multiple services at the same time, such as making a FaceTime call and transferring large amounts of data.
What is RPM?
RPM is a measure of a round trips per minute, indicating how many transactions your device can do over the Internet in one minute. The higher the rpm score, the better your user experience will be.
How does it compare to ther tests?
Responsiveness is a new way of measuring your networks quality, focusing primarily on the reactivity of your network during simultaneous use by multiple devices or multiple services. One other test measure throughput or ping latency, responsiveness adds another dimension to enable you to evaluate the network quality.
They do have a link to a KB Article link at the end of the explanation n but it 404’s…
So what does this mean? Well, i’ll be honest I wasn;t sure what it was doing or how it was doing it but I channelled my inner MacKenzie and did a packet capture…
Here it is if you want to look for yourself.
Turns out it’s a bunch of RTS/CTS
This makes perfect sense but seems to go against some of the things Apple are saying in their descriptions of what’s happening… in the KB Article they mention SQM (Smart Queue Management) which for me was a way of fixing buffer bloat at the router… they also mention that RPM is measuring “how many transactions your device can do over the Internet in one minute”.
So are we testing WLAN performance or Internet performance? The packets seem to suggest its WLAN performance but Apple is indicating its WAN performance…
Maybe more testing is needed!!
