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You're being ADSL

Posted on 2 Jul 2002 at 17:12

While ADSL in the US seems to be standard fare, in good old Blighty we're taking it a bit more slowly. And we're right to be wary, says Steve Cassidy

Everybody buys computer stuff on the numbers, and nobody wants to know how many people can actually share a single miserable 64Kbits/sec ISDN line. The emphasis is all on hairy-chested 'big iron' networking and wide area connections. I've seen up to 15 people Web browsing through a single 64Kbits/sec line with hardly a complaint, and half a dozen people happily using Citrix MetaFrame down the same width of connection (though when I come home at night and start my mail, newsgroups and cached Web pages coming, I can saturate my own link for 20 minutes or more using four machines).

The point is that what techies do isn't the same as what regular users do, and sizing a connection to cater for the techies is never a good strategy. BT has taken this view by setting its contention ratios - the number of ADSL lines that share a common onward connection to the rest of the internal BT network - so that home users are on 50:1, while business users are on 20:1.

How broad is your band?

For a more realistic evaluation of ADSL, take a look at the Direct Connection services page on www.dircon.net/products.html where there's a handy little table of the different grades of connection, with the 'upstream' bandwidth number clearly presented (that's the speed from you to the ADSL termination, not the speed each user gets to the rest of the world). It basically states that ADSL technology is for single PCs only by default, and you'll need an ADSL-compatible router if you're a business that needs to link multiple PCs. 'Local content' and other buzz phrases don't even get a look in.

The confusion over how much bandwidth you need to serve x users with y amount of traffic has spawned an entire industry of Bandwidth Calculators on the Net, the cutest that I've seen in my quick survey being at www.kessels.com/WebTimer/. This will give you a feel for whether your line is genuinely too slow or whether, in fact, you're simply looking at slow sites (for whatever reason). A great temptation for network administrators is to go for at least a 256Kbits/sec line because it's appealingly faster than the despised home user will ever be able to afford, but the bandwidth calculator does a good job of showing why this isn't such a good assumption.

My opinion of ADSL, as you might expect, is now lukewarm. I think that BT's choice of wording on its site could easily backfire - it appears to promise a 512Kbits/sec connection, when the fact is that only in very ideal circumstances will an end user see 512Kbits/sec. The truth, as known to ISPs and those running small networks with properly-sized external connections, is that few people use anything like the bandwidth they think they're using, and every trick in the book can be pulled - proxies, local and remote caches, network 'chokes' on each user - without the end user being any the wiser. So will I be queuing up for ADSL? Very probably. Will I be recommending it to other private users? With caution. Will I be recommending it to businesses to replace a traditional leased line connection? As presently specified, no.

The Lotus eaters

There was an old saying 'DOS ain't done until Lotus won't run', a bitter reflection on the fact that each revision of MS-DOS made a worse mess of Lotus 1-2-3, which the wags and phrase-coiners figured might not be so accidental. It seems things still stand that way between Lotus/IBM and Microsoft, as if the grand 'market wars' of the mid-1990s are still being fought in one last arena: email systems. More blood is currently spilled over Domino vs Exchange than anything else I've seen lately, and with very good reason. Email turns out to be the way into the hearts of many users who haven't yet been caught up in the sales wars: get an email system into a company and it becomes very hard for them to disengage.