ADSL Details

IP Stream ADSL (Broadband)

IP Stream ADSL is the platform recommended for business use because it is a higher quality line, effectively delivering more bandwidth. Unlike Data Stream lines an IP Stream line cannot be further contended by the provider (see contention below).

Data Stream ADSL (Broadband)

Data stream broadband is a lower class of line and is often used by ISP for residential customers. It is not uncommon though for Data Stream lines to be sold to businesses because they are cheaper and far too often price is all that is considered.

The Myth About 8Mb “Max” Broadband Service

The most significant point about 8Mb broadband is that it is rarely if ever 8Mb at the users office. This is because the service degrades the further you get from the exchange and due to the quality of the line and connections along the way. Even if you were located next door to the exchange you are unlikely to achieve the top speed of 8Mb. 8Mb broadband is a rate adaptive service which means that during the first 10 days of service the line will try to achieve the fastest stable speed. The speed of the line will increase steadily until the quality degrades then the line is reset. Doing this repeatedly for up to 10 days will enable the line to establish the highest speed at which it is stable and then it is fixed at that speed.

Contention Ratios

A contention ratio or 20:1 means that 20 users can effectively share the same line. Of course as businesses we would all like to have a dedicated line but that is not financially viable on an ADSL line. If 20 other users sharing your line seems like a lot, then consider that businesses are frequently sold 50:1 contention ratio lines. BT tend not to quote these figures for their lines any more, some say because they could not guarantee that the figures were not exceeded. ISP’s have been known to take a 50:1 contention ratio line and contend it even further within their own network so contention ratio is a significant aspect to consider.

ADSL2+

With many exchanges now becoming ADSL2+ enabled this gives businesses and consumers alike the opportunity to significantly increase the potential of their ADSL provision. In theory, ADSL2+ can have a download speed of 24Mb and an upload speed of 2Mb. This is a significant increase in performance but still suffers from the issue of degradation over distance from the exchange. Still if your particular location is subject to 50% degradation let’s say, 50% of 24Mb is better than 50% of 8Mb.