[toast0]

Bufferbloat is alive and well. Try a t-mobile 5g home gateway. Oof.

I think cable modems have had a ton of improvement, and more fiber in our diet helps, but mobile can be tricky, and wifi is still highly variable (there's promising signs, but I don't know how many people update their access points)

[commandersaki]

Is it though, or is it just a scapegoat or a red herring, especially in the case with a wireless medium? That's been my experience with quick claims to bufferbloat, it's usually something else at play. But again ymmv.

[Zarathustra30]

There's always something else at play. Bufferbloat hides problems from the systems that can easily solve them. It doesn't cause problems, it makes them worse.

[toast0]

I mean, I did a speed test with t-mobile 5g home internet, download speed was impressive, but so was the difference in ping time during the download vs otherwise.

Sure, wireless is complex, but there were definitely some way too big buffers in the path. Add in some difficulty integrating their box into my network, and it wasn't for me.

[commandersaki]

Fair enough, I concede with your assessment, my understanding of bufferbloat (which I have to relearn everytime I look at it) is that the telltale sign is ping to any destination that traverses the uplink exhibits higher latency than usual when you're saturating your download. It's just a tricky thing to test given variability of conditions (and what might be deemed as expected operation) which is why I'm usually hesitant and sceptical, and I don't trust those speedtest websites to gauge it properly.

[ectospheno]

Every speed test I tried that measures latency under load shows a large difference between fq_codel on and off.

[esseph]

This is very much a problem ISPs have to deal with as big pipes feed small pipes.

[commandersaki]

What do ISPs have to actually determine these issues outside of sketchy speedtest websites and vague reports or concerns from customers? What about placing probes in the correct places (e.g. in conditions where there is no additional loss or introduced latency between the end user and uplink). Also is this an actual problem that users are really having, or is it perceived because some benchmark / speedtest gave you a score.

There's a lot of issues and variables at play; this isn't a case of "it's always DNS". What tools do ISPs even have at their disposal and how accurate are they and does it uncover the actual problem users are experiencing? This is the real issue that ISPs of all size have to deal with.

[ryao]

You don’t need a speed test website to see this problem. Just run a ping on your own while doing a big download that saturates your connection and bufferbloat will happen unless there is some active queue management to prevent the ping packets from waiting in the queue behind the download packets. This happens anytime that there is a fast/slow transition in the internet and the slow connection cannot keep up. To prevent packet loss, the packets will be buffered, which works well for short spikes, but prolonged activity will result in a noticeable backlog and if buffers are allowed to be sufficiently big, you can get arbitrarily long delays, which are visible in ping times.

The worst that I have ever seen was about 30 seconds when visiting a foreign country where bufferbloat was occurring at peering links. The bufferbloat in peering links is likely visible from western countries if you ping residential IPs in developing countries and monitor the ping times over days. Some parts of the day will have very high ping times while others will not. The high ping times will be the buffer bloat.

In most western countries, the bufferbloat typically occurs at people’s home internet connections. As is the case in all cases of buffer bloat, the solution is to be willing to drop packets when the connection is saturated. If you limit the bandwidth just below what the connection can handle, you can do active queue management to solve the problem.

That said, I suggest you stop posting replies. Your crusade against the idea of buffer bloat makes you look bad to anyone with enough networking knowledge to understand what bufferbloat is. I also strongly suspect I wrote an explanation that you will take zero time to understand and rather than take my advice, you will post another reply to continue your crusade. :/

[toast0]

> Also is this an actual problem that users are really having, or is it perceived because some benchmark / speedtest gave you a score.

The actual problem is I'm on a voip call and someone starts a big download (steam) and latency and jitter go to hell and the call is unusable. Bufferbloat test confirms that latency dramatically increases under load. Or same call but someone starts uploading something big.

If troublesome buffers are at the last mile connection and the ISP provides a modem/router, adding QoS limiting downloads and uploads to about 90% of the acheived physical connection will avoid the issue. The buffers are still too big, but they won't fill under normal conditions, so it's not a problem. You could still fill the buffers if there's a big flow that doesn't use effective congestion control, or a large enough number of flows so that the minimum send rate is still too much; or when the physical connection rate changes, but good enough. Many ISPs do this, and so you hear a lot less complaining about bufferbloat on say Comcast these days; also, this is an effective best practice, so less need for papers, reports and case studies... it's a matter of getting the practices in the wild and maybe figuring out how to do it better for wireless systems with rapidly changing rates.

Otherwise, ISP visibility can be limited. Not all equipment will report on buffer use, and even if it does, it may not report on a per port basis, and even then, the timing of measurement might miss things. What you're looking for is a 'standing buffer' where a port always has at least N packets waiting and the buffer does not drain for a meaningful amount of time. Ideally, you'd actually measure the buffer length in milliseconds, rather than packets, but that's asking a lot of the equipment.

There's a balance to be met as well. Smaller buffers mean packet drops, which is appropriate when dealing with standing buffers; but too small of buffers leads to problems if your flows are prone to 'micro bursts', lots of packets at once potentially on many flows, and then calm for a while. It's better to have room to buffer those.

[esseph]

codel/CAKE also came from that project, no middlebox needed.