[Cerowrt-devel] Problems testing sqm

Sebastian Moeller moeller0 at gmx.de
Sat Oct 24 03:59:02 EDT 2015

Hi David,

On Oct 24, 2015, at 00:48 , David P. Reed <dpreed at reed.com> wrote:

> Sqm is a way to deal with the dsl or cable modem having bufferbloat. In the configuration described neither end is the problem ... the DUT itself may have bufferbloat.

	But our claim is that we “solved” (at least wired) buffer bloat. And in his case the failure of even our reference platform wndr3700v2 to keep sane latency under load hints at issues; with a configuration issue, or some yet un-solved corner issue with our solution.

> That would be terrible.

	I agree, so let’s try to figure out what is happening here..

Best Regards

> On Oct 23, 2015, Richard Smith <smithbone at gmail.com> wrote:
> On 10/23/2015 02:41 PM, Michael Richardson wrote:
> Richard Smith <smithbone at gmail.com> wrote:
> My test setup:
> Laptop<--1000BaseT-->DUT<--1000baseT-->Server
> So, given that the DUT is the only real constraint in the network, what
> do you expect to see from this setup?
> Given that the probably DUT can't forward at Gb/s, and it certainly can't
> shape anything, it's gonna drop packets, and it's probably gonna drop them in
> Rx, having overrun the Rx-queue (so tail-drop). If there is too much ram
> (bufferbloated), then you'll see different results...
> Setting ingress/egress to 10Mbit/s I expected to see the speed 
> measurements bounce around those limits with the ping times staying in 
> the low double digits of ms. What I saw however, was the data rates 
> going well past 10Mbit limit and pings up to 2000 ms.
> This is what I've seen in prior rrul testing using a the 50/10 cable 
> link at our office and my 25(ish)/6 link at my apartment and a well 
> connected server on the net. That however was using QoS and not SQM.
> Its that a reasonable expectation?
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