Re: [Bloat] DSLReports Speed Test has latency measurement built-in

["Bill Ver Steeg (versteb)" <versteb@cisco.com>]

For a very low speed link, I suggest that 100ms is not the right target. At 1 Mbps (which is a downstream number that I occasionally see in an ISP), 100ms is only nine 1400 byte packets. 

Non-paced IW10 would suggest that you need to have at least a 10-deep target. Concurrent flows probably drive the target a bit higher. An FQ_AQM solution would have a different target than an AQM solution.

Does anybody have data that quantifies the best target delay for FQ_Codel and Codel/PIE?

Bvs


-----Original Message-----
From: bloat-bounces@lists.bufferbloat.net [mailto:bloat-bounces@lists.bufferbloat.net] On Behalf Of Toke Høiland-Jørgensen
Sent: Friday, April 24, 2015 4:29 AM
To: Sebastian Moeller
Cc: bloat
Subject: Re: [Bloat] DSLReports Speed Test has latency measurement built-in

Sebastian Moeller <moeller0@gmx.de> writes:

> I know this is not perfect and the numbers will probably require 
> severe "bike-shedding”

Since you're literally asking for it... ;)


In this case we're talking about *added* latency. So the ambition should be zero, or so close to it as to be indiscernible. Furthermore, we know that proper application of a good queue management algorithm can keep it pretty close to this. Certainly under 20-30 ms of added latency. So from this, IMO the 'green' or 'excellent' score should be from zero to 30 ms.

The other increments I have less opinions about, but 100 ms does seem to be a nice round number, so do yellow from 30-100 ms, then start with the reds somewhere above that, and range up into the deep red / purple / black with skulls and fiery death as we go nearer and above one second?


I very much think that raising peoples expectations and being quite ambitious about what to expect is an important part of this. Of course the base latency is going to vary, but the added latency shouldn't. And sine we have the technology to make sure it doesn't, calling out bad results when we see them is reasonable!

-Toke
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