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ADSL - Acceptable Speeds defined

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There's quite a big debate over what is considered as an acceptable speed for IP Stream adsl.

IP Stream adsl is provisioned as a contended service. Traditionally this was 50:1 for Home Products and 20:1 for Office Products. To find more about contention and what it is read my Contention Page.

However, BTw have never actually provisioned adsl on the VP's at this ratio - to do so would mean that speeds would be pretty abysmal and since October 2005 BTw have now started declaring what speeds they find acceptable on their part of the IP Stream Network.

2 Mbps
400 kbps
800 kbps
1 Mbps
200 kbps
400 kbps
512 kbps
100 kbps
200 kbps

Maxdsl BTw STIN 441 states

Max services where the line operates at 2Mb or above may provide End Users, at peak times, with the same data throughput as they would have experienced on an equivalent 2Mb fixed rate Broadband service.
Max services where the line operates below 2Mb may provide End Users, at peak times, with the same data throughput as they would have experienced on an equivalent fixed rate Broadband service (ie BT IPStream Home Max service which operated at 500kbps would have an equivalent service at peak times of that of a BT IPStream Home 500kbps service).

The BT Handbook also gives a further guide

For BT IPstream Max users synchronising at 2272kbit/s or above the BT network through the BRAS will provide a minimum of 2Mbit/s throughput for 90% of the time.
For BT IPstream Max Premium users synchronising at 3424kbit/s or above the BT network through the BRAS will provide a minimum of 3Mbit/s throughput for 90% of the time.

/.. snip .. / We do operate capacity management processes to upgrade capacity in the BT network where performance consistently does not meet these performance levels.

BT Wholesale Speed Test.

To check what speeds you are achieving on the BT side of the Network then you will need to log off from your ISP's network and conduct a BTw SpeedTest. Details on how to do this can be found here.

The BTw speedtest involves you logging off from your ISP, to perform a speedtest which completely eliminates any of your ISPs network. If you are getting slow speeds on the BTw speedtest, then the problem doesn't lie with your ISP, instead it means that the problem is either with your own equipment or congestion on the VP at the exchange.

So what can you do about this?

Hopefully BTw will have already realised that there are problems at your exchange and will have arranged a "fix date". You can check if there is a fix date due by using the checker at either Plusnet UserTools Exchange Checker.

If your exchange is marked as red and has a fix date set, I'm afraid that you may simply have to "grin and bear it" until that date :/

If no fix date has been set it could mean that BTw aren't aware of a problem yet, or the exchange checker hasn't been updated with recent information.

If you are seeing slow speeds, and no fix date has been set then you should complete several BTw speedtests and report the results of these with your ISP.

Reporting to your ISP.

Hopefully your ISP will take this up with BT. ISPs have guidelines set before they can report problems to BT.

On May 11th 2005, BT set the following guidelines to ISPs in a briefing to help set customer expectations.

  • Speeds of between 400Kbps and 2000Kbps are perfectly acceptable for a connection based on the 50:1 Home 2000 product. For other speeds and products see the table below.
  • Even if an exchange is Red and the speeds are consistently below the threshold of 400-2000Kbps, then a fault may be reported.

"The throughput benchmarks for BT IP Stream Home are listed in the table below. These would be regarded as normal service."

2 Mbps
400 - 2000 kbps
800 - 2000 kbps
1 Mbps
200 - 1000 kbps
400 - 1000 kbps
512 kbps
100 -  500 kbps
200 -  500 kbps
256 kbps
50 - 250 kbps

BT state that "speeds outside of these ranges will only be investigated once the customer has discounted any elements which they control" these are listed as:-

  1. The number of End Users that are active across the service provider's BT Centrals
  2. The volume of IP traffic generated compared with the size of BT Central or number of BT Centrals that the service provider has chosen to deploy.
  3. The amount of Internet peering bandwidth employed by the service provider.
  4. The status of the traffic congestion on the Internet.

Conducting a BTw SpeedTest completely eliminates any of the above 4 factors.

"Due to variations within IP networks, especially the Internet, testing should be replicated at suitable time intervals to determine if external influences are affecting performance. A suggested minimum is a test off peak and another at peak times both using the same test facility"

One point to note is that nowhere does it state that the poor speeds must be experienced during an off-peak time before it can be reported to BT. Normal speeds during off peak (ie early hours) simply help clarify that it is congestion on the VP during peak times and that the user is still capable of achieving good speeds if it wasn't for peak time congestion.

Another moot point regarding off peak testing is that the above statement implies that tests can be taken at an external test facility (that could be affected by peak Internet traffic in general). Therefore although the BTw Speedtest would be the best way of testing off peak speeds, it doesn't exclusively mean that the BT speed test should be used off peak to verify speed problems if the user can get good off peak speeds on other speedtests during this period. *

Contact with BT Wholesale

As adsl customers, we are classed as "End Users" and your ISP is actually BTw's "Customer" because it is your ISP that is buying services from BTw.
As such BTw wont speak to us end users without having gone through the correct channels which is through your ISP, so there is no way that we can contact BTw direct to report any problems.

One final note to bear in mind, if BTw do contact you regarding any speed problems that you have, be aware that they will try and fob you off with various excuses. So make sure your own equipment is not faulty and that you have conducted the necessary BTw speed tests.

One excuse that I've heard them try several times now (and actually had it tried on me) was that "its a problem with your own ISP". Be firm on this - If you have conducted the BTw Speedtests and they are also giving you low speeds then there is no way that they should be able to blame your ISP as the BTw speedtest completely takes any part of your ISP's network out of the loop.

* A conversation I had with Ben Verwaayen's office in July 2005 implied that it was the first they had heard of the "00.00 to 07:00 BTw speedtest rule". I was told that as long as you could prove that you were getting consistently low results then your ISP should be able to raise this with BT as a fault.... the 400 kbps is not set in stone either.

Special thanks to Phil Long from Zen for clarification on the BT Wholesale acceptable guidelines.

Update:- a copy of the benchmark statement can be found here

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