On 24 May 2021, at 06:09, Livingood, Jason via Bloat 
<[email protected]> wrote:

> I’m looking for opinions here re bloat-busting techniques like AQM in the 
> context of network neutrality (NN). The worry I have is whether some 
> non-technical people will misunderstand how AQM works & conclude that 
> implementing it may violate NN because it would make interactive traffic 
> perform better than it does today. That is true of course – it’s a design 
> goal of AQM, but non-interactive traffic performs as well as it always has – 
> it is not disadvantaged.

There’s a faulty assumption buried in this, a common misunderstanding that we 
need to correct.

Consistently lower delay benefits *all* applications. The lower the round-trip 
time, the better TCP fast-retransmit works. TCP connection setup is faster. The 
TLS handshake is faster. The less buffering in the network, the less 
application-layer buffering is required for streaming video, giving quicker 
startup times, and quicker random access. If you try to make a list of 
applications that *don’t* benefit from lower delays, you’ll probably end up 
with an empty list.

This is why I’ve been advocating for making low delay available for *any* 
traffic that chooses to opt-in to this smarter queue management, not 
selectively for just some privileged traffic. I’m not making any subjective 
value judgement that video conferencing traffic is more important or more 
deserving that streaming video traffic, or weather forecasts, or driving 
directions, or software downloads. I do not support traffic prioritization 
schemes that privilege some traffic types over others. I support making low 
delay available to *all* traffic that agrees to behave properly and cooperate 
to keep the queues short -- meaning packet pacing, responding appropriately to 
congestion signals, etc.

Delay reduction is not an either/or choice. In order for some traffic to 
benefit other traffic doesn’t have to suffer. It’s not a zero-sum game. 
Eliminating standing queues in network buffers benefits all traffic. This can 
be hard to communicate because it seems counter to human intuition. It sounds 
too good to be true. In normal human life this is uncommon. When first class 
passengers board the plane first, all economy passengers wait a little bit 
longer as a result. Computer network queueing doesn’t operate like that, which 
makes it hard to explain by analogy to everyday experiences that most people 
understand.

I talked about this six years ago in my presentation at the Apple developer 
conference:
<https://developer.apple.com/videos/play/wwdc2015/719/?time=2702>

There’s also a neat demo a little earlier in that same video:
<https://developer.apple.com/videos/play/wwdc2015/719/?time=2520>

Stuart Cheshire

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