Guide to ADSL and Cable Broadband - Part 2 of 3

Though cable broadband is not as readily available as ADSL, it is on the increase in the UK and is already well-established in the United States where there were more than 22.5million cable modem users as far back as 2005. So how does cable broadband work and what are its advantages?

What is cable broadband and how does it work?

A cable modem allows data to be sent over the cable television structure by taking advantage of unused bandwidth on the network. As a result you need to live in an area that is served by cable – but you do not require a BT phone line.

In the UK, most of the cable internet connections are supplied by Virgin Media. Previously they were supplied by ntl:Telewest, but Virgin Media completed a takeover of the group in 2006. If you do not already have a cable line, you will need to arrange for a representative to visit your home and install a line – usually this will be accompanied by a set-up fee

The installation process sees a cable modem attached to a coax cable which goes outside the house and on to a cabinet in the street. In order to work with your PC, it is usually necessary to install a LAN card – this is something you will usually have to do yourself as engineers generally won’t get involved in the set-up process. In effect, although it is called a ‘cable modem’, it acts more like a network router.

Many cable modems will also incorporate their own router alongside the modem functionality. Even though they may appear within the same device, functionality is kept separate from the modem. As a result, both the wireless router and the cable modem will have their own distinct IP and MAC addresses.

Cable modems are usually available as part of a broadband package from most leading providers. With other services you can buy or rent a cable modem directly from the supplier.

As with ADSL the download speeds available on cable are much higher than the upload speeds. However, cable broadband has potentially faster download speeds than ADSL and can even get as high as 50Mb for some business broadband packages. Some cable companies may allow you to run your own web server at home but bear in mind that your IP address may be replaced periodically which can make access difficult.