 Contention begins at the exchange and is often defined by standard ratios such as 50:1 (ADSL). This means that you are competing with 49 other people for your ISP’s limited bandwidth, which could be a backhaul connection of just a few Megabits (Mbps). There are usually more than 50 people on a 50:1 product via any given exchange, but that very much depends on package speed, backhaul size and how your ISP makes the balance between them.
 At first glance this might seem like a doomed design, given that a small group of heavy users could conceivably fill up any bandwidth to the detriment of others. However in reality this usually doesn’t happen because people rarely surf, run at the packages full “advertised” connection speed and download all at the same time, thus capacity is balanced throughout the day. Where did it all go wrong? Earlier this year ISPreview ran an interesting article that involved several ISP’s being interviewed on a number of key subjects (article – ‘ISP’s Talk Migration, ADSL2+ & MAX’), two of the questions posed concerned the impact of faster broadband technologies. It’s worth reading for a better insight into what we’re about to explain. During late 2005 and into early 2006 - ISP’s, especially BT based ADSL providers, began introducing ever faster services. Packages offering ‘up to’ 8Mbps or higher have since become the norm, including a greater emphasis on Capacity Based Charging (CBC). This did two things:
Initially there weren’t many problems, outside of a few notable technical issues, but as more and more consumers switch onto increasingly faster products it becomes clear that existing capacity isn’t keeping pace. Exchanges that had already been ‘crammed’ full of people suddenly began seeing significant drops in speed. Typically ISP’s moved to purchase additional capacity, but at costs of around £300,000 (BT) per annum for a single 155Mbps pipe it is an expensive investment and one dependant upon the “balanced usage” methodology explained earlier. Without the aggressive use of this philosophy everybody would be paying upwards of £100 per month for their broadband. There has also been another and equally significant change, the growing availability of online content, specifically video, music and Internet TV (IPTV) services. This content boom has caused consumers to make more active use of their connections, shifting people away from the living room TV and back onto computers. [Next Page (3)]>>
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