ISP Review - ISP's On ADSLMax Concerns

ISP Review Questions ISP's Over ADSLMax Problems

ISP's On ADSLMax Concerns
By Mark 'Winter' Jackson : Jun 7th - 2006 : Page 2 of 5

"Yes we have noticed this - a stable 2mb line can and does operate at say 1.5mb and BT claim this is acceptable."

2) Prior to ADSLMax many surfers will have experienced rock solid pre-set speeds on their line, yet after the regrade some have witnessed speeds dropping significantly below their pre-MAX setting.

BT has been cagey about dealing with such complaints, sighting ADSL as a “best efforts” service and pointing to 400Kbps and below as the only level where it becomes truly concerned. Surely this should not be the case, especially with MAX being billed as “faster”.

Do you not feel that the system should operate some kind of safeguard, determined by a lines pre-MAX best speed, so that the connection never falls below its pre-MAX level? This would also give customers some confidence and criteria with which to judge their ISP’s ability to deliver the service.

******: Yes we have noticed this - a stable 2mb line can and does operate at say 1.5mb and BT claim this is acceptable. The Max products should at a worst case operate at 2.5mb if on a line that previously managed 2mb. The trouble comes with the FTR and the MSR set by BT on the lines after the 10 day period. With the contention ratio applied to the FTR it really does bring the minimum speed of a line right down and lowers the point at which speed issues can be reported.

Vispa: I think that would be nice, yes, but this is not IPStream, its MAX and as such works differently. I think a much wider trial should have been completed before this went on general release but then I’m not a BT technician. In the early days of ADSL I was one of the BT guinea pigs and believe me, the service was shocking, working for a few hours a day if you were lucky. The support was equally appalling with the poor BT support bod reading from his script every-time you called. As the weeks turned to months the service improved and it wasn’t long before they got it right and we have the service (IPStream) we now enjoy more or less stable and more importantly, reliable.

I don’t think it will take them too long to iron out the bugs in the DSL MAX systems that are causing the issues. I just wish they would be honest with us so we can inform our customers accordingly. People understand there can be issues and while they do not like it they are prepared to put up with it providing they are kept informed of progress. It’s when we have nothing to tell them that it becomes an issue because that makes us, the ISP look incompetent!

NewNet: We have had some users experience lower throughput speeds than they were achieving with their previous fixed rate service. It is probably fair to say that users have tended to check speeds much more than perhaps previously – bringing the lower speeds to the fore. Some users have found that regarding to MAX has highlighted deficiencies within their own local cabling and with micro-filters etc. But – it is clear that some users have experienced variable speeds and throughputs lower than they expected.


There is confusion between the download sync speed and the actual throughput. Sync speed is the speed that the end user modem or router synchronises with the DSLAM at the local exchange – and will be dependent on line length, line quality and other factors (and may vary according to local factors including random electrical interference (noise). Throughput is dependent on many external factors including remote server load and performance, contention with other users in the virtual pipe, core network, ISP connection and external networks.

Unfortunately the end user expectation has been set by advertising – Download speeds up to 8Mb/s (particularly by BT). There is a mis-match between what BT may understand by ‘Download Speed’ and that of the end-user. The end-user will see this term as relating to throughput – BT see it as the sync rate between the CTE and the DSLAM.

------[specific response to the last paragraph of Q2]------

I can understand the feeling behind this – but cannot agree that this should be the case. MAX is a more sensitive technology than the fixed rate service and is more dependent on local conditions – including local user wiring, quality (and availability or otherwise) of micro-filters. It is likely that very little will change as far as the ISP is concerned – any differences may well be due to the change in delivery (from fixed rate to MAX ADSL) and outside of the control of the ISP.

There is a reported problem that BRAS settings have reverted to the previous fixed rate speed. BT are aware of this and are expecting a fix within the next 10 days.

I would not want users to feel that any change in service (negative change in service) was due to the ISP – almost certainly not the case.

3) There is a fear that the instability of ADSLMax speeds (in relation to no.2 above) could, in the future, be used as an excuse by some providers to cover their own performance problems.

Do you foresee this as a concern, not so much for your own provider, but the industry as a whole?

******: Yes, I think a lot of ISP's will use this as an excuse to cover performance issues. But I think it will be most apparent with those ISP's that only have 1 BT Central, as the smaller the inter-connects to BT the more likely contention will apply to the ISP itself. A bigger concern though would be those ISP's that offer unlimited services without any safeguards. A 8mb line running continually at say 6.5mb for a day can download 70GB or 2100GB in a month - usage at that level, which is not uncommon, rapidly saturates BT Centrals - which will effect the speeds of all other users.

Vispa: Yes I do see this as a major concern. The problem here is that I do not believe the VP’s in the actual exchange have enough bandwidth to cope and I also believe that some of the smaller ISP’s like ourselves are going to suffer as well. The problem we have is that just a handful of MAX users (say half a dozen) all hammering P2P downloads will have the ability to bring a 34Mb central to its knees! You do the maths 6 X 6Mb = 36Mb. This is a central that is capable of handling at least 1200 consecutive connections with ease. I do not believe that BT have worked this into their equations.

NewNet: There is no doubt that MAX has increased the demand on ISP networks. ISPs are having to look at increasing network capacity to meet demands, potentially requiring substantial investment. ISPs are aware of the pattern of usage on their networks and can compare performance levels to usage patterns.

But, the pattern of low customer reported speed does not always mirror the ISP utilisation pattern – many users report slow speeds even when ISP networks are at lowest levels of utilisation.

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