That new fangled ADSL2 thingy

[esh]

Hi folks, looking for a little input, information and guidance.

While some of you are sitting in the (comparative) luxury of a (occasionally functional) FTTC/FTTP connection, it has come to my attention that BT are going to replace the Commodore 64 at my local exchange for something that supplies ADSL2 in the next two months. What I'm looking for is any advice as to whether to investigate this so-called "upgrade" further or hold off. Let me describe the current situation.

Currently on a priority-enabled ADSL Max IDNet connection. It has been very reliable. It is used for (apart from the usual net and email) offsite backups and also enabling us to access files on our local NAS from in the field in a secure manner, receiving the files with any changes being done from the office immediately propagating, which is very handy. Also due to a long story that I won't go into, it's hosting a scientific database which at some times of the year gets a heavy beating during the night hours. For this reason, upload is quite important. More so than the download, if truth be told. But first and foremost, reliability is the no. 1 - this is why I came to IDNet, and why I invested considerable time in setting up a specialised router recently.

ADSL2 promises higher upload and download. Most notably on download, but breaching the mythical 1Mbit upload boundary is tempting. However, I question as to whether I really would see an improvement, and perhaps you can advise here. Over the past year my 8128 synced connection with a 7150 profile has remained steady, but the download speed has started dropping. In 2008, I achieved regular speedtests of 6.9Mbit down, which is pretty much the theoretical boundary for ADSL Max. I'm now somewhere in the 5Mbit regime. Upload has gone from a consistent 83KB/s to 60KB/s. This isn't bad by any means, but it's always disappointing watching your pristine grade line trail off into mediocrity; I was clearly "above average" on speedtest.net two years ago, now I'm sub-par. Alarmingly, at the peak off-peak time (that's midnight-2am, of course!) I now get about 1Mbit down. If BT is really chocked up like this, will I see any improvement at all? Firstly, does anybody have a clue for reliability between the two products?

Download caps I do not mind, my maximum in a month is scraping 40GB. This isn't really important.

Thanks for any insight.

[Steve]

The reality is I believe is that you won't have a choice,if your exchange is adsl2+ enabled you'll be moved over sooner or later. I would hope you'd be ok as you must have a relatively short line so should see an improvement in both upload and download speeds. What we don't know is how 'noisy' your line is as that is key to a successful adsl2+ migration.

[Gary]

The reality is I believe is that you won't have a choice,if your exchange is adsl2+ enabled you'll be moved over sooner or later. I would hope you'd be ok as you must have a relatively short line so should see an improvement in both upload and download speeds. What we don't know is how 'noisy' your line is as that is key to a successful adsl2+ migration.

When I used LLU my attenuation went up, I take it this is a frequency change with adsl2+ Steve? In my new home I sync with interleaving off at 8128 getting the same as eesh pretty much and my noise margin is 12-13 db, so would that make for a good adsl2+ line when and if BT ever upgrade the big key that needs to be wound each day in our exchange to keep the cogs turning 

[DorsetBoy]

ADSL2+ is more sensitive to noise than Max so that will be what governs your throughput.  My LLU ADSL2+ line can synch at around 15 - 16Meg  we get noise bursts here 3 -4 times a day which means the line just stops working at that synch, I had to have the SNR pegged and synch dropped to get over this. I now have a synch around 12 meg and throughput of @10.  My Max line was on fast path, 448/8128 profile of 7150 and throughput @ 6.8meg .  ADSL2+  here needs a low level of interleaving.

[Gary]

ADSL2+ is more sensitive to noise than Max so that will be what governs your throughput.  My LLU ADSL2+ line can synch at around 15 - 16Meg  we get noise bursts here 3 -4 times a day which means the line just stops working at that synch, I had to have the SNR pegged and synch dropped to get over this. I now have a synch around 12 meg and throughput of @10.  My Max line was on fast path, 448/8128 profile of 7150 and throughput @ 6.8meg .  ADSL2+  here needs a low level of interleaving.

Not much chance of us getting any LLU here Dorset, we are a backwater rural BT exchange.

[DorsetBoy]

Not much chance of us getting any LLU here Dorset, we are a backwater rural BT exchange.

That is what I thought Gary, it is not supposed to be available here either and Samknows insists I cannot be on the service I am using  several exchanges that do not list other services do have them.

[Steve]

I think with people on longer lines i.e > 40db downstream att the switch to adsl2+ becomes a bit of a lottery,it just depends how noisy the line is. Unfortunately BT seems to regulate noisy/high error rates on adsl2+ with a banded profile (which has hit some people quite hard). The imposition of a banded profile stabilises the connection as the imposed reduction in downstream sync forces the downstream margin up.

There is a way out for poor performance on adsl2+ and that's to be re modulated back to adslmax

[DorsetBoy]

I think with people on longer lines i.e > 40db downstream att the switch to adsl2+ becomes a bit of a lottery,it just depends how noisy the line is. Unfortunately BT seems to regulate noisy/high error rates on adsl2+ with a banded profile (which has hit some people quite hard). The imposition of a banded profile stabilises the connection as the imposed reduction in downstream sync forces the downstream margin up.

There is a way out for poor performance on adsl2+ and that's to be re modulated back to adslmax

I am on a fairly short line, Max attenuation was 26db , ADSL2+ works in a higher frequency band and is affected by interference a lot more, apparently the "Max" traffic may even be one of the noise problems.

[Gary]

Im on a 32db line, new copper underground so at night it hardly fluctuates which is good, just checked and the only LLU on our exchange is talktalk! So that's out the window for a start. Still no date for WBC. 

[Rik]

The short answer is no-one can give you a definitive answer, esh. For me, my attenuation went up from 57 to 63db, but I still managed to achieve 3.5M rather than 2.5M, with an upload of around 800k. I'm on a 6db target, with interleaving off. By contrast, my Max line could manage a slightly higher upload speed, but needed interleaving on and a 9db target NM for stability.

With ADSL2, we have learnt that this is an indefinable issue called quality, which is not reflected in the stats that the router reports. For the same figures, two people can get widely different results. In addition, the router/MSAN combination has become more critical than was the case with Max.

As has been said, if your exchange has been enabled, sooner or later you will be moved to an MSAN, as  BT remove the DSLAMs - though not necessarily to ADSL2.

In short, I'd be inclined to try ADSL2 and see how it works for you. If it doesn't, IDNet can have you remodulated back to Max.

[esh]

Do I get any warning if I'm going to be moved over anyway? I wonder how quickly this sort of thing happens. If it's very noise dependent, I was thinking of replacing all the faceplates and cabling with good quality stuff (as opposed to "whatever I found in the bottom of the drawer" which is apparently good enough for ADSL1).

I guess I should look into cost as well.

[DorsetBoy]

The noise issues seem to be more in the local environment between home and exchange.

Warning, I believe support send you an email prior to the change over.

[Rik]

What Dorset said and, yes, the better your internal wiring, the stronger chance you have of good results.

[Technical Ben]

Not much chance of us getting any LLU here Dorset, we are a backwater rural BT exchange.

I don't know. There is a good chance you could "catch" the dreaded "TalkTalk" bug. 

[Gary]

I don't know. There is a good chance you could "catch" the dreaded "TalkTalk" bug. 

Thats here, but I'm ignoring it 

[Technical Ben]

It amazes me they could unbundle a ball of yarn let alone a Exchange.

[Rik]

It depends on the conversation, Ben.