21CN: It's not the data saviour

If there's more, we'll take more


Column It does seem to be a rule of data processing that we use all we can get of it. As BT starts to test its 21st century networking (21CN) with partners like Entanet, it's a safe bet that this rule will mean the dream of universal high speed data will turn sour as people try to squeeze more data through a limited pipe.

The world of broadband is, largely, a mess right now because of this rule. When we first heard of ADSL, most of us looked at our 54 kilobit modems and just swooned at the thought of all that bandwidth - 512 kilobits.

And today, we have eight megabit download speeds and "free broadband for life" - and yet, somehow, the service seems to stutter and hiccup, and drop. And then there are the "unlimited" downloads which are unlimited until you reach the maximum.

Just for fun, I set up a TalkTalk broadband installation and ran a ping test. Over an hour or so, the number of pings lost averaged about 20 per cent or more. I tried talking over Skype with it, and pretty much gave up. It works fine for browsing the web, and that's pretty much it.

So when 21CN starts its trials in Birmingham this November, there will no doubt be those who say "Wow, 24 megabits. That won't get congested." And they will be wrong.

The problem with ordinary broadband is that a lot of ISPs assumed they could work out their data budgets by calculating how much stuff people wanted to download. Much to their astonishment, it turns out people want to upload too.

And the main problem with people uploading isn't the obvious one (that the upload capacity is inadequate) but that the data they upload is being downloaded too. It multiplies all traffic to the point where congestion becomes a real problem.

As one small ISP recently complained to me: "To stay in business, we've had to cut prices. But the prices we pay to the network operator are fixed. So today, we cannot supply a 100 per cent 24/seven service. We can't even supply 100 per cent times Contention Ratio 7x24 to all users. We have to rely on the fact that most users don't use anything like that level of their available bandwidth most of the time."

But as peer to peer services become more popular, the amount of bandwidth used goes up. And for anybody using an internet phone, like Skype, the first effect of that is that there are blips and glitches and interruptions in the speech.

Skype strenuously denies this, but talking to customers, I find a general acceptance of reality: the once-excellent audio quality is now only good for a short time - after five minutes of a conversation it tends to degrade.

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