Re: [aqm] ping loss "considered harmful"

Mikael Abrahamsson <swmike@swm.pp.se> Mon, 02 March 2015 10:17 UTC

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Date: Mon, 2 Mar 2015 11:17:33 +0100 (CET)
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Brian Trammell <ietf@trammell.ch>
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Cc: bloat <bloat@lists.bufferbloat.net>, Dave Taht <dave.taht@gmail.com>, "cerowrt-devel@lists.bufferbloat.net" <cerowrt-devel@lists.bufferbloat.net>, "aqm@ietf.org" <aqm@ietf.org>
Subject: Re: [aqm] ping loss "considered harmful"
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On Mon, 2 Mar 2015, Brian Trammell wrote:

> Gaming protocols do this right - latency measurement is built into the 
> protocol.

I believe this is the only way to do it properly, and the most likely 
easiest way to get this deployed would be to use the TCP stack.

We need to give users an easy-to-understand metric on how well their 
Internet traffic is working. So the problem here is that the users can't 
tell how well it's working without resorting to ICMP PING to try to figure 
out what's going on.

For instance, if their web browser had insight into what the TCP stack was 
doing then it could present information a lot better to the user. Instead 
of telling the user "time to first byte" (which is L4 information), it 
could tell the less novice user about packet loss, PDV, reordering, RTT, 
how well concurrent connections to the same IP address are doing, tell 
more about *why* some connections are slow instead of just saying "it took 
5.3 seconds to load this webpage and here are the connections and how long 
each took". For the novice user there should be some kind of expert system 
that collects data that you can send to the ISP that also has an expert 
system to say "it seems your local connection delays packets", please 
connect to a wired connection and try again". It would know if the problem 
was excessive delay, excessive delay that varied a lot, packet loss, 
reordering, or whatever.

We have a huge amount of information in our TCP stacks that either are 
locked in there and not used properly to help users figure out what's 
going on, and there is basically zero information flow between the 
applications using TCP and the TCP stack itself. Each just tries to do its 
best on its own layer.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se