What is “working latency”?June 15, 2022
Apple and Ookla have recently launched new tools for measuring real-world network performance 1,2 . They measure “working latency,” but what is it exactly 3,4 ?
In short, working latency measures how badly other internet traffic can affect your video conference or gaming session. Let me explain:
Most computer networks are idle most of the time. When you measure latency on an idle network, for instance by pinging Google, you typically get the best-case latency. This is a bit like using Google maps travel times outside of rush-hour traffic and assuming that that is how traffic conditions are at all times of the day.
What about travel times during rush-hour traffic? That is where the problems are likely to be anyways, right? Tests for working latency create traffic to ensure the network is working on something, and then measure latency. This produces more realistic results because we often travel during rush hour (it’s rush hour for a reason!). In fact, your own everyday internet use, like loading a website or sending an email, can trigger a short-lived rush-hour event. Many home routers allow “greedy” applications (like internet browsing, downloads, and video streaming) to cause delays for latency-sensitive traffic (video conference, gaming). Working latency measures how bad this can get.
Ideally, the working latency should be as close to the idle latency as possible. If the difference between the two is more than 30 ms, it is likely to cause problems. The good news is that the issue can be fixed, even if your ISP does not cooperate 5 . If your network has this ailment, here are a few things you can do:
Try calling your ISP and asking why their working latency is bad
Upgrade your home router and WiFi network
Change some devices, like game consoles, to Ethernet instead of WiFi
You can test your working latency right now, using this excellent tool directly from the browser: https://www.waveform.com/tools/bufferbloat
ISPs can use methods like Broadband Forums QED 6 standard to monitor working latency in their networks.
Finally, a big thanks to the folks at the bufferbloat mailing list for their help in editing and reviewing this article.
1 Apple’s RPM (Round-trips per minute): https://randomneuronsfiring.com/using-apples-rpm-tool/
2 Ooklas “loaded latency” (Android/iOS): https://www.ookla.com/articles/introducing-loaded-latency
3 BITAG report, “Latency Explained” https://www.bitag.org/documents/BITAG_latency_explained.pdf
4 Working latency is related to bufferbloat. More resources here: https://www.bufferbloat.net
6 Broadband Forums QED standard: https://www.broadband-forum.org/download/TR-452.1.pdf