A guide to ADSL Broadband MAX

All 2020Media broadband services use BT ADSL MAX. This offers the fastest broadband speeds available using existing BT lines.

Why is ADSL MAX different?

ADSL Max offers faster download and upload speeds than the standard ADSL service.
ADSL Max Premium offers a maximum downstream line rate of 8Mbps and a maximum upload speed of 800Kbps.
ADSL Max Standard offers a maximum downstream line rate of 8Mbps and a maximum upload speed of 400Kbps.
ADSL Max Premium traffic is prioritised over ADSL MAX Standard traffic.

ADSL MAX is rate adaptive - what does this mean?

The rate adaptive nature of ADSL MAX means that you will get the best speed possible from ADSL taking into consideration environmental factors that effect ADSL MAX, such as distance from the BT Exchange and quality of copper.

Faster speeds with ADSL MAX?

How line rate varies with distance from exchange

The speed that you see through your ADSL MAX broadband can be dependent on many factors including the contention of your ISP and the performance of any hardware, PC, Servers, Switches etc.

This said, ADSL Max usually gives a faster speed than standard ADSL.

As a rule of thumb it is good practice to plan for around 50% data throughput of the quoted downstream rate of your ADSL MAX broadband. There can be wide variations from speedtest sites and servers at different times of the day. The official speedtest site is http://speedtester.bt.com/

ADSL MAX routers provide a sync speed of up to 8128Kbps. Many routers sync at this speed but most ADSL MAX circuits' peak throughput is around 6500Kbps.

Download performance will be below the quoted line sync rate. If the router sync rate is showing 8128Kbps then the maximum throughput will be 7150Kbps. If the ADSL MAX broadband sync is 3000Kbps then the maximum throughput will be 2500Kbps. Under normal business conditions ADSL MAX throughput is likely to be below these throughput rates.

How does ADSL MAX work out the optimum speed

When upgrading to ADSL MAX the BT network synchronises between the ADSL router and the DSLAM in the BT Exchange at regular intervals to identify the Maximum Stable Rate or MSR.

The sync data is collected over the training period where both the upper and lower line rates of the ADSL MAX are identified. After the 10 day training period the lower line rate is rounded down to produce the MSR. A figure 30% below the MSR is taken as the Fault Threshold Rate or FTR.

What is the 'training period'?

The training period is typically known as the first 10 days after an ADSL MAX installation where the router synchronises with the DSLAM in the BT Exchange. Data is captured to determine the optimum ADSL MAX sync speed.

The BT network system stores the line sync data provided by the DSLAM and outputs a line profile known as the BRAS setting. BT runs Digital Line Management DLR on the ADSL MAX and the line characteristics are continually monitored. If the sync falls below the previously set line rate then retraining will automatically occur. If the line quality improves automatic retraining will not occur and manual re-sync is required.