Why isn’t my broadband fast? It could be the contention ratio.
Have you ever signed up to a supposedly super-fast ADSL2+ broadband internet plan, but discovered the speed you were getting at home was much slower than advertised? This could be the result of the contention ratio at your local phone exchange. Put simply, the contention ratio is how many people are sharing the same internet connection from the local exchange’s DSLAM infrastructure.
In the world of computer networking, the ratio of potential maximum users on the internet to actual bandwidth available to them all is called the contention ratio. The problem of a slow broadband speed arises when a large number of people attempt to get on the internet at the same time, but there’s only so much bandwidth available for them to collectively use. This is most obvious at peak times in the evenings or on weekends when many people want to get online simultaneously. The total amount of bandwidth available for your personal use can diminish rapidly.
So what does this mean for people researching which internet service provider to sign up with? Ask what their contention ratio is! Most ISPs offer between 20:1 and 50:1. If you’re on a 20:1 contention ratio, this amounts to sharing your bandwidth with 19 other subscribers. Therefore, the lower the ratio the better for you, as the chances of having too much web traffic on the information superhighway is lessened.
Contention is a standard feature of all ADSL broadband connections that sadly has to be dealt with. 50:1 is quite a common ratio for most residential users, but lower ratios are available, often for a higher cost. If you are sharing your connection with 49 other people, some of which just happen to be heavy users who dedicate their free time to downloading movies and watching online TV, things may get frustrating at times.
For this reason providers have special business deals that offer ratios of between 10:1 and 20:1, so that companies need never worry about having a slow connection to the internet. However, it should be noted most residential users rarely have any issues with a 50:1 ratio. It’s only a problem when numerous users are downloading large amounts of data at once.
Another question to ask the provider is how many ports they have available within their DSLAM equipment at your local exchange. If they’ve rented out nearly all of their ports, there’s a higher chance numerous people will be on the web at the same time. Each connection at the exchange hooks into a single port, so a lot of free ports amounts to having less people to share your bandwidth.
Also important to be aware of is there are numerous other variables that could be affecting your broadband speed, such as how far away your home is from the local telephone exchange. The further you are from the exchange, the slower the connection is when it reaches your property. The copper wire telephone infrastructure may also be old or faulty, and there’s always the chance your modem or actual computer has issues that need attention. If the problem is a direct result of your contention ratio, do your utmost so that it doesn’t create a ‘contentious’ issue at home!