[Cerowrt-devel] Equivocal results with using 3.10.28-14

Sebastian Moeller moeller0 at gmx.de
Mon Feb 24 17:02:35 EST 2014

Hi Fred,
On Feb 24, 2014, at 16:24 , Fred Stratton <fredstratton at imap.cc> wrote:

> How are you measuring the link speed?
> With SQM enabled, I have speedtest.net results far below the values at which the gateway syncs.
> IF the gateway syncs at 12000/1000, the speedtest figures are 9500/850
> The performance I obtain with streaming video is very good, tweaking the extra settings in SQM on 3.10.28-16
> I am sure you are aware that you will never achieve the values quoted by the ISP.

	But the current rate given by the modem is a pretty true measurement of the bandwidth between the modem and the DSLAM, independent on the marketing numbers of the ISP ;)

> How long is your line? Downstream attenuation is a proxy for this.

	Once the sync is working this does not matter any more, having seen Rich's line stats, he has a very clean ADSL with SNRM of 22 and 11 and almost no errors (not even many FECs).

Best Regards

> Are you using ADSL2+, or some other protocol? Does the device even tell you?
> On 24/02/14 14:36, Rich Brown wrote:
>> CeroWrt 3.10.28-14 is doing a good job of keeping latency low. But... it has two other effects:
>> - I don't get the full "7 mbps down, 768 kbps up" as touted by my DSL provider (Fairpoint). In fact, CeroWrt struggles to get above 6.0/0.6 mbps.
>> - When I adjust the SQM parameters to get close to those numbers, I get increasing levels of packet loss (5-8%) during a concurrent ping test.
>> So my question to the group is whether this behavior makes sense: that we can have low latency while losing ~10% of the link capacity, or that getting close to the link capacity should induce large packet loss...
>> Experimental setup:
>> I'm using a Comtrend 583-U DSL modem, that has a sync rate of 7616 kbps down, 864 kbps up. Theoretically, I should be able to tell SQM to use numbers a bit lower than those values, with an ATM plus header overhead with default settings.
>> I have posted the results of my netperf-wrapper trials at http://richb-hanover.com - There are a number of RRUL charts, taken with different link rates configured, and with different link layers.
>> I welcome people's thoughts for other tests/adjustments/etc.
>> Rich Brown
>> Hanover, NH USA
>> PS I did try the 3.10.28-16, but ran into troubles with wifi and ethernet connectivity. I must have screwed up my local configuration - I was doing it quickly - so I rolled back to
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