Sonic → Re: Uncapped ADSL2+ with SNR margins vs. Capped ADSL

Thanks to all who replied!

Sonic has capped (fixed?) my bit rate at 6.008 Mb and ADSL (DSL1?) and and things are working better, although I am still losing sync a few times each night depending on how many neighbors have lamp dimmers running and how badly the PG&E poles are arcing nearby :0. (I'm a radio ham and I can hear the interference on MF/MF frequencies, and it is correlated with DSL performance.) I found a Cat3 RJ11 to RJ11 patch cable with seems to have helped a little.

To refine my original question: What would be the speed/stability tradeoffs of 6 Mb DSL1 and whatever the default SNR margin setting is (6db?), vs trying a DSL2 or 2+ connection, with the SNR margin bumped up to 12 or 15 dB?

OTOH Sonic very quickly "capped [my] line at 6008kbps and locked the service type to ADSL" so I assume that is the preferred approach to my situation.

-wsanders

I should add - in the next couple weeks I plan to install a whole house splitter, which should be good for a few db of SNR reduction. I can also give a before/after report on the SNR as reported by my modem.

Switching from the original ADSL (now often called ADSL1 to avoid ambiguity) to ADSL2 uses the same transmit power and frequency range but due to protocol enhancements is able to increase the maximum downstream data rate from 8Mbps to 12Mbps.

I'm not sure whether any of the changes make the ADSL2 signal more sensitive to noise but if not then you should see higher speed with ADSL2.

ADSL2+ is an entirely different story because of the expanded frequency range.

I suggest you pick a time when the call volume at Sonic.net is low (it shows on their website) and ask a support person to spend some time with you to try whether switching to an ADSL2 (not ADSL2+) profile will get you more speed.

Thanks - I tried unchecking ADSL2+ and leaving ADSL2 enabled on my modem before Sonic locked me down. My sync rate dropped down to 6-ish from 7-1/2-ish. My CO distance is about 9K ft so this is about what you'd expect. So as far as I can tell both 1 and 2 negotiate the same speed.

However, the SNR reported by the modem for all proto versions was 6 +- a few db, which is the default for Cisco DSLAMS. As I understand it the SNR reported by the modem should more or less match the margin configured at the DSLAM end.

So as an experiment I might see if Sonic can reenable 2 or 2+ and bump up the margin to 9,12,15, or whatever dB. Based on what I can find out about the protocol, this may actually result in the circuit training more frequently, with negligible speed increase. I can't recall but either 2 or 2+ is also supposed to retrain a lot faster than 1, also.

I'll understand if they can't - they may just have a few profiles available to use. Their techs are great but they might go crazy tweaking individual params for every customer 9k ft+ from the CO.

6 Mb is a neighborhood speed record. I'm happy with even sub-6-Mb downloads (800 k uploads would be nice though), but streaming audio is the killer app at our house and we and prefer stability to speed.

We have ASSIA DSM available on the network - rather than guess, I'd suggest you just ask our staff to push the loop into PO (performance optimization), and let is work it for four or five days. It takes some time as it gathers stats, but in many cases achieves stability and max stable rate. It's quick, easy, and works better in many cases than manual settings.

-Dane

Thanks Dane, I'll give it a try. Great job you are doing with Fusion!

Back on ADSL2 (not +), we enabled interleaving and all the hard frame errors went away and were replaced by correctable ones. There is a negligible effect on latency. The line is synced at 8 down and 1.2 up and dropped an internet radio stream only twice last night between 10 and midnight and there were no further drops between midnight and 8 AM. We'll leave the performance monitoring stuff on for a few days and see what happens.

I've also made a few changes to my inside wiring - I cut the loop of crappy untwisted 4-pair at the computer desk wall jack and wired in a pseudo-whole-house splitter dongle in such a way that it's a straight run from the NID to the DSL modem, then downstream to all the house phones. Sooner or later I'll install a Cat-5 run from outside to the modem, and a real whole house splitter.

Good job!