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What is ADSL? David Dorn examines the latest buzzword in internet connections and answers some of the questions you may have about it. To start right at the beginning, ADSL stands for Asymmetric Digital Subscriber Line – and it’s the “DSL” bit that’s the important one. At the very simplest level, ADSL is a digital connection between your PC and the Internet, much like a network card connects your PC to another in your building. Where ADSL differs from the dialup modem or ISDN connection you’re probably using now is that it’s “always on” – that is to say, there’s meant to be no break in the connection – if you click on a URL that you have a shortcut on your desktop, it should open immediately. Speed So that’s the very simple theory – what about speed? Well, it’s fast. The basic provision in the UK is 512kbits per second downstream and 256kbits per second upstream. Compared to a V90 modem, which does 33kbits per second upstream and (in theory) can do 56kbits per second downstream, ADSL is up to ten times faster. That means that a large download that might take ten minutes on a V90 modem will happen in around a minute on ADSL. Can anyone have it? That depends on where you live. At the moment, you need to be connected to an exchange that is enabled for ADSL (or RADSL), and be within about 5.5 kilometres from it as the copper crawls. The latest incarnation of ADSL is RADSL (Rate Adaptive DSL), which has a greater distance tolerance than ADSL, which really only works up to around 2.7 kilometres from the exchange. The easy way to find out whether you can have either flavour is to order it from your preferred source and let them do the line test. If it passes, you can have it. If it doesn’t you can’t. There are no hard and fast rules, unfortunately – it’s all down to the line quality. How do I get it? This is quite straightforward. You place an order, the line is checked and if it passes, an engineer will come to install it. (R)ADSL piggy-backs your existing telephone line, which you can still use, even while you’re “online” and using the ADSL connection. There’s nothing for you to supply other than a PC to connect it all to – your chosen provider will supply all the technical gubbins and boxes to make the thing actually work. I’ve got a home network what are my options? You can go two ways here – one way is to order a network enabled ADSL installation, which is aimed, frankly, rather more at businesses, and therefore tends to cost rather more. Alternatively, you can order a single user installation (which usually runs via USB) and install Internet Connection Sharing on the PC your ADSL line is connected to. That way, all the machines on your network can take advantage of the increased bandwidth you’ll have. What’s this “Upstream” and “Downstream”, then? Anything you send from your PC to the Internet goes “upstream”, while anything you receive to your machine from the Internet comes “downstream”. So, when you click on a hyperlink, your browser sends a few characters upstream to request the page that the hyperlink points to, and the the page comes downstream to your PC so you can see it. You send very little information upstream, but get a lot back downstream – hence the difference in speeds. The only time that tends to change is if you maintain a Web site, in which case you’ll be sending lots of information upstream when you FTP you pages to your host server – but it’s still a whole lot faster by ADSL than it is by dialup. I need a static IP address You’re not alone. Many services and FTP upload sites for secured services require that anyone entering them can be uniquely identified by IP address. Originally, ADSL was dynamic IP only, but most providers now offer static or fixed IP addresses – usually at a small premium. So, yes, you’ll be OK for doing your online work with a new ADSL installation. Would I be better off with cable? It’s early days to say, yet. One of the challenges with Cable is that cable modems share bandwidth with all other users on that leg of the cable network – and the signal is prone to Radio Frequency interference. ADSL, at the moment, is reported to be consistently faster. So, it’s all down to price and whether or not you can get a cable connection. I want to continue using AOL and/or CompuServe or other similar providers Good for you. It’s not a problem. AOL and CompuServe both allow a “telnet” connection, where you can, as long as you’re a member of either service, use their respective software over an Internet connection you have already started. The hows vary from version to version, but it’s very easy to set up, and could make your AOL or CompuServe experience an awful lot faster. Of course, AOL will be able to provide you with ADSL soon anyway! (click here to find out more) Anything else I need to know? Yes. If you only ever come online once a week, ADSL is not for you. If, however, you regularly find that your connection is too slow for you to do what you want to do in the time you have available, or if you spend lots of time online – perhaps you work from home – then it’s very much worth investigating further. If you’re an online gamer, then why are you still here? Go get it ordered!
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