ADSL1 gives better sync speed than ADSL2+ (noisy line)

A few weeks I posted about this, but I now note that since setting my router to ADSL1 (G.dmt) instead of ADSL2+ I'm definitely getting a better sync speed!

Since my line was upgraded to 21CN last march I've mostly been getting a sync of 6656 which gives me a 5.5MB bras rate, but a few weeks ago I tried tweaking the settings on my router (the aaisp supplied zyxel P-660HW-T1 v2) and have have changed the modulation type from ADSL2+ to g.dmt (ADSL1) using the router command: wan adsl opencmd gdmt. It can also be changed via the web interface I think.

I have also noticed that the online "ping graph" seems to show a lot less green ping spikes since using ADSL1, so it definitely seems better for noisy lines. Hopefully my bras profile will eventually update to 7150 but I realise this can take up to 3 days.

Conclusion: I'd say that this is a good tweak for anyone with a noisy line who is getting poor speeds under ADSL2+

My routers stats under adsl1:

P-660HW-T> wan adsl chandata
DSL standard: ADSL_G.dmt
near-end interleaved channel bit rate: 0 kbps
near-end fast channel bit rate: 8128 kbps
far-end interleaved channel bit rate: 0 kbps
far-end fast channel bit rate: 1024 kbps

Edited by deleted (Sat 02-Jan-10 18:40:06)

and what does adsl2 give you (adsl2 not adsl2+)

Hi

ADSL1 is probably giving you a better connection simply due to compatibility between your kit when using ADSL2+ and the kit at the exchange.

If you had a modem/router using a different (or newer chipset/firmware) you may well find the opposite is true.

Everyone's mileage will vary with something like this, and the technology used in ADSL2/2+ should give a faster sync but only where compatibility issues don't exist.

Regards

Phil

In reply to a post by Chrysalis:

and what does adsl2 give you (adsl2 not adsl2+)

Chrysalis - I did try ADSL2 for a few days, but it still seemed to show quite a few errors. Also I notice that both ADSL2+ and ADSL2 showed green "spikes" on my ping graph, but ADSL1 does not show these spikes. Generally green spikes when line is inactive are not good news!

eg (green spikes) http://boliston.files.wordpress.com/2010/01/greengra...

versus (no green spikes) http://boliston.files.wordpress.com/2010/01/nograss1...

Edited by deleted (Sun 03-Jan-10 14:23:49)

yeah not good then

I would suggest try a different router, some routers just dont handle adsl2/+ good at all.

Do you have the stats for your line when you were on ADSL2+?

I have thought about trying this and you have just sparked my interest again.

Matt

my stats are with ukonline who utilise easynet LLU kit so different but is an example.

on adsl1 I have tried 3 different routers, speedtouch 585v6 netgear dg834gt and billion 7402. All achieved similiar synch speeds, the variable been stability, out of the 3 the speedtouch was the most stable.

on adsl2/+ a very different story. All 3 routers synch badly on adsl2+, on adsl2, the speedtouch and netgear 834GT got mid to high 5000's albeit not very stable. The billion 7402 achieves anything from about 5800 to 7400kbit, its variable because the service supports SRA which varies the synch speed without disconnects and also the time of day. I also tried a 4th router on adsl2 the netgear dg834v5 which uses a similiar chipset to the billion 7402 and synched well. So one router on adsl2 would get me around 5500-5600 not that stable on adsl2 and another 5800-7400 (average around 6400) with uptime of many months and no packet loss. These are all estimates from memory as its months since I used a different router on this line.

In reply to a post by PhilipD:

Hi

ADSL1 is probably giving you a better connection simply due to compatibility between your kit when using ADSL2+ and the kit at the exchange.

I don't think so. When Sky put my home ADSL service on to ADSL2+, my sync speeds immediately dropped from 5000kbps to 3500kbpps. This was tested on a variety of routers (including Sky's supplied DG834T), and the result was always the same. My lines (I have two ADSL connections) are both very noisy, and ADSL2+ doesn't seem to work well with noisy lines.

My AAISP business ADSL connection is being migrated over to AAISP's Be service next week, and it will be interesting to see how that performs if there is an option to try ADSL2+ on that.

Hi

I don't think so. When Sky put my home ADSL service on to ADSL2+, my sync speeds immediately dropped from 5000kbps to 3500kbpps. This was tested on a variety of routers (including Sky's supplied DG834T), and the result was always the same. My lines (I have two ADSL connections) are both very noisy, and ADSL2+ doesn't seem to work well with noisy lines.

All lines are noisy

If ADSL2+ struggled with noisy lines it wouldn't be giving the majority of people that use it a faster speed.

Something is wrong with your line and connection or the kit you tried all had the same compatibility issue, a full tone chart and line stats from ADSL1 and ADSL2+ on your line should go a long way to see what is happening, if you have them lets have a look.

Regards

Phil

unless I am mistaken the majority of adsl2+ users in the uk are still using LLU isp's and those isps tend to cherry pick short lines.

Its not unusual for a long line to synch lower on adsl2+ than adsl1. However I would expect adsl2 to improve on adsl1.