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What is Cable Broadband? Iain Laskey looks at the less well known competitor to ADSL – broadband cable. Dave Dorn recently gave the low-down on ADSL which you can read about here. ADSL isn’t the only player in the game though and may even be considered a Johnny-come-lately as broadband cable was available a few months before ADSL. How do they compare? Cable modems are currently available from Telewest and NTL and as such are only available if your area has cable TV provided from either of these two companies or some of their subsidiaries. Cable modems use the same cabling infrastructure as cable TV and accordingly hang off the same connection to your home as cable TV does. The cable modem is attached to a coax cable which then goes to the outside of the house then on to a cabinet in the street. The cable modem connects to the PC via a LAN card. Prior to installation it is normally required that you already have the LAN card installed and configured as the installation engineers normally won’t touch this part of the setting up. It is worth mentioning that the term cable-modem is slightly misleading as it isn’t actually a modem but more akin to a network router. Like ADSL, cable modems are always on 24 hours a day, 7 days a week. Once you are setup by the installation engineer you become a permanent part of the Internet. You never need to request a connection or to dial up. However, you need to be more responsible with your Internet usage and installing a good firewall and anti-virus package are a must if you wish to avoid any nasty intrusions from hackers. This is the same as with ADSL. Speed Whilst cable can go much faster, the current UK implementations only support a maximum of 512kbits per second. However, the cable modems are capable of much more, the speed being throttled down by the cable companies. In due course it is expected that premium services offering speeds such as 1Mbit/sec or 2Mbit/sec will be launched. Like ADSL, the upload speed is slower than download speed but still much faster than any normal modem could manage. How do I get a cable modem? Depending on the area you live in, you either contact your cable supplier - whoever that may be. Some allow you to buy or rent a modem but some only rent as part of the overall package. Unlike ADSL, cable modems neither use nor have any effect on your existing phone lines. What am I allowed to do with a cable modem? Networking your PCs such that they all share the cable-modem is genrally OK although if you have problems with any PC other than the one that was initially configured, you are on your own. Some cable companies will allow you to run a web server but you must password protect it and limit the number of connections that it supports. This might sound like good-ish news but bear in mind that periodically you are allocated a new IP address so trying to access your web server reliably can be difficult without utilising some sort of dynamic IP address mapping service elsewhere on the web. Other services If you wish to access AOL, Compuserve or other services you can by using a LAN or telnet type connection. This is easily done via each system’s setup screen. Odds and ends If you’re a gamer, you may prefer ADSL over cable as cable can get a bit ‘bursty’ sometimes with periods of high speed interrupted by short periods of treacle-like performance. This is no real problem when web browsing or downloading files but could be the kiss of death in the middle of a Quake III frag-fest. On the other hand, cable is currently much cheaper than ADSL. Ultimately it depends on what you need high speed for and your Internet habits.
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