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by emerongi 2627 days ago
I have a 4G modem. Whenever I watch a video and skip forward a bunch of times, the connection hangs and I have to wait for about a minute before it resumes normal operation.

Is this bufferbloat? I guess what happens is that a bunch of packets get queued up and I have to wait until all of them are delivered?

3 comments

Yes, that sort of jerky behavior is symptomatic of bufferbloat. Multiple 4G and 5G devices have now been measured as having up 1.6 seconds of buffering in them. They are terribly bloated. It was my hope that the algorithms we used to fix wifi ( https://www.usenix.org/system/files/conference/atc17/atc17-h... ) - where we cut latency under load by 25x and sped up performance with a slow station present by 2.5x - would begin to be applied against the bufferbloat problem there. Recently google published how much the fq_codel and ATF algorithms improved their wifi stack, here:

http://flent-newark.bufferbloat.net/~d/Airtime%20based%20que...

Ericson, at least, published a paper showing they recognized the problem: https://www.ericsson.com/en/ericsson-technology-review/archi...

and I do hope that shows up in something, however the chipsets on the handsets themselves also need rational buffer management.

That's probably something else. The server rate limits your client, or the ISP rate limits due to too many bursts, or the client needs to buffer more of the video.

To exclude cases you'd need to watch the network traffic with something like WireShark and look at retransmissions. If it suddenly shoots up and then packets start to trickle later but very slowly, then that could be bufferbloat.

But the 1 minute seems too long.

The whole connection hangs - it's not the server or buffering and I doubt it's the ISP.

Reading more about it, you are correct about 1min being too long, therefore it's probably not (just) bufferbloat.

Probably not. It's just crappy software.