The gist of my problem is that my upload profile was 10Mbps, then 20Mbps after the upgrade, but my achieved speed has never been more than 5.7Mbps, which is exactly what the BT checker predicted.

It may just be that due to the distance of your property from the cabinet (or possibly external influences such as electrical noise) that is the best that can be achieved on your line.

Might be worth asking the BT folks if they can tell you what speed your line is actually synchronised at with the cabinet DSLAM (as opposed to what the profile is set to or the BT checker estimates say).

If the line can only physically manage to synchronise at say 6Mbps then no amount of fettling the profile upwards is going to make any difference (if indeed it has any part to play at all as they seem to suggest).

I'd hope the BT Retail staff have access to this information to aid their diagnostics rather than it being held 'secret' by Openreach (part of the BT Group but operated entirely separately).

Your two posts triggered a thought, unfortunately not directly related to the question.

I can't remember seeing any BT speed test results for FTTC where the upstream IP Profile has not been either 10Mbps or 2Mbps. Neither however can I remember ever seeing an upstream IP Profile on ADSLx.

Bear in mind that on FTTC we have two overlapping DLMs .

Openreach have a "product setting" to cap the line speeds. I don't think they have IP Profiling within that. That DLM is the actual line controller, with (surmising) ISP-requested settings passed in from ...

... the BT Wholesale DLM, which I think applies a patch in its original downstreaming profile system. That takes the sync reported by Openreach and generates an IP Profile at around 97.69% of sync. (See Bald_Eagle1 posts). ADSL2+ sets it to 88.2%. IPSC (ex ADSL) appears to apply the original "up to 8Mbps" profile table.

(The BTW IP Profile has always done as you surmise - stop traffic too fast for the line arriving at the DSLAM).

Now I start guessing/proposing. It is highly likely that the BT Wholesale DLM contains fields for both downstream and upstream IP Profile, in case an upstream one was ever required. Pre-fibre, I suggest that was always filled with 448/832kbps for ADSL, and some unknown number for ADSL2+. (1.4/2.5Mbsp?).

To function on FTTC that upstream field needs a value. 2000/10000/(15000)/20000.

Discuss .

I don't have FTTC myself so I am speculating and extrapolating from knowledge gained over far too many years working in telco / ISP land.

Your explanation makes sense - the upstream profile figure may only exist because it 'must' e.g. it is a mandatory value in some underlying system or database, but is not actually used for anything so is just populated with the maximum upload speed dictated by the product specification. However, the actual governance of the upload is achieved using line synchronisation parameters e.g. the cabinet dslam caps the maximum upstream synch rate to 2Mbps, 10Mbps, 20Mbps etc. as per the product and then at synch time the line makes best efforts to achieve up to that speed.

With that in mind there would be absolutely no point doing any profiling further upstream, it would just be unnecessary configuration and management overhead on network devices upstream into the core.

So in the OP's case I suspect the best upstream synch speed the line can achieve is ~6Mbps - clearly in this circumstance changing the maximum allowed upstream synch from 10Mbps to 20Mbps on the DSLAM achieves nothing - the line is still just making best efforts. So actually when the BT Care folks suggest that referring to the Openreach checker estimate is more useful than referring to the IP profile. However, one sincerely hopes they have access to diagnostics tools that can tell them what the actual line synchronisation speeds are (along with the other useful stuff like SNR, attenuation, error measures etc.)

Yes, without explicitly saying so, I was agreeing with you and providing a plausible explanation of how the DLM programmers' moinds worked several years ago.

As for

However, one sincerely hopes they have access to diagnostics tools that can tell them what the actual line synchronisation speeds are (along with the other useful stuff like SNR, attenuation, error measures etc.)

and anything similar. Nope!

The estimates on the Wholesale checkers were produced by Moses. The attitude throughout the BT Group is that they are right, and no evidence to the contrary is accepted. The figures from engineers' test equipment is ignored. This has been the case for years.

We had a case the other day where a disgrunted user stuck on a 2Mbps upstream FTTC product, where it was obvious he could get more, was refused even at BT CEO level.
http://forums.thinkbroadband.com/bt/t/4114496-help-p...

I think it's unfair to pile the whole BT Group into one bag like that. From my experience there is still plenty of realistic boffinry going on regards improving testing, diagnostics and repair in dusty corners not just within the BT Group but also within the industry as whole.

I see two main reasons for the perceived decline in flexibility when it comes to this area. The rigid chinese walling of the various companies within BT Group (and within other large players in this industry) and the industry-wide desire to compete for custom purely on price-point alone.

I won't go on in a public forum, it could be detrimental to me

And no, I don't nor ever have worked for any part of the BT Group before anyone accuses me of astro-turfing.

The Group CEO Office should be able to cause action to be taken when Openreach engineer equipment reports a line is achieving upstream speeds 700% greater than a database says. Particularly when the upstream figure reported is consistent with the user's actual downstream and the estimates are consistent with each other.

Nothing to do with Chinese Walls. Simple common sense. Little technical understanding needed, and that should be easily obtained through a 3-minute internal phone call.

We are not talking about the high-tech areas. We are talking about obvious database errors, with no acceptance that they could be wrong, never mind there being no system facility to correct them.

In reply to a post by RobertoS:

I can't remember seeing any BT speed test results for FTTC where the upstream IP Profile has not been either 10Mbps or 2Mbps. Neither however can I remember ever seeing an upstream IP Profile on ADSLx.

Bear in mind that on FTTC we have two overlapping DLMs .

Openreach have a "product setting" to cap the line speeds. I don't think they have IP Profiling within that. That DLM is the actual line controller, with (surmising) ISP-requested settings passed in from ...

My results on speedtester.bt.com have always said 20mbps for the upload (except of course when I was on the 40/10 service). Downstream IP profile varies according to my downstream line speed, however nomatter what my upstream sync speed is, upstream IP profile has always remained at exactly 20.

I think the ideas proposed for why are correct as well - i.e. that there is no need for upstream profiling as the rate limiting hop of the line itself is already past by the time data reaches the profiler.

So while one can reasonably accurately deduce their downstream sync speed from their downstream IP profile, the upstream profile provides no such clues and there is no way whatsoever for a customer using the official equipment as provided to see their upstream sync speed.

It is certainly not the case that your upload will only be what the checker states, as the checker states I'll get 53/13 and this speedtest suggests otherwise.

What's more likely the case is nomatter what your IP profile states, your upstream will be the maximum your line can support up to the limit of the service you're paying for. In this case it just seems the checker was exceptionally accurate with its prediction.

Edited by deleted (Thu 03-May-12 03:01:57)

WOAH there tiger. I was simply trying to explain how the internal machinations go in the industry without elucidating.

If you want to rage by all means continue to hit [email protected]

The attitude throughout the BT Group is that they are right, and no evidence to the contrary is accepted.

I posed some questions in private, and response was similar, i.e. nothing wrong with products. It is the tester, or wireless, AV software or PC.