Guy Kewney

Is your broadband connection faster than your modem? What a stupid question to ask, you might think, as if it wasn't obvious.

I mean, modems provide 50Kbps at their best and ADSL is 10 times that, at 512Kbps. So, of course, your broadband must be faster. Well, it isn't.

Part of the problem seems to be deep and complex, but the rest is awfully simple. The hidden bits are really well hidden in the way BT (in particular) runs its network; not the bit in the exchange, but the lines that connect the exchange to the rest of the network.

The simple bit is that the figures that provide the number of 512Kbps don't actually say: 'This is what you get.'

If you connect a pipe that takes 10 gallons a minute to a pump that delivers one gallon a minute, you don't have to be a brain surgeon to realise that you're going to get a gallon a minute at best - and only as long as there's water to pump.

The complex bit is what happens behind the scenes inside BT's network. People who know how that network is configured say there's no difference in the service BT provides to its 512Kbps and 2Mbps customers.

The 2Mbps service looks faster, but that's only because relatively few people use it. In actual fact, the contention ratio inside the BT network is the same for both services.

Now that people are starting to really stress the network, they're finding out that the sceptics are right. If you haven't found this yet, trust me - you will. The fact of the matter is that ADSL isn't only inadequately provisioned, but obsolete.

Look 10 years into the future and the typical household, equipped with two high-definition TV servers plus a standard (for 2013) broadband data feed, will need (absolute minimum) 100Mbps. And that's a typical household.

I recently sat through a tutorial by Seagate on the subject of the differences between a hard disk and a hard disk. If the hard disk is inside a personal video recorder, it has to cope with five (or six) simultaneous data streams being written to, and read from, the hard disk surface.

The incoming (two) video channels are both written in real time, plus a data stream. Then two video channels can be read off in real time to two different viewers and to a DVD writer.

Believe it or not, that application is hugely easier for the disk to handle than reading fragmented files off a Windows PC.

There's capacity on the disk - typically 80GB - to cope with far more bandwidth, both in and out. To me, that means people will want to use this capacity. Why restrict a TV recorder to two channels? Who would not want three or four?

Imagine a household with four simultaneous HDTV input channels coming down the fibre. You're looking at around 150Mbps.

But you simply can't do that down BT's twisted-pair copper wire using DSL technology. And the backbone that BT uses to feed the IP stream to the exchange couldn't come close to coping.

We can be sure that the costs of high-speed switches and routers will drop. Even so, one thing is inescapable: the communications infrastructure is going to need investment to cope with the demands of the future.

Probably, by the time we've installed the communications links capable of delivering it, DSL will be so much a thing of the past and you can pretty much expect to be the only user on your block.

At that time, it may become popular, perhaps, for reverse channel control of satellite links. Otherwise, I think it's time to admit that ADSL is a fad of the last millennium, which was delayed into this one by incompetence.

It will disappear pretty soon.

Like this story? Spread the news by clicking below:

 del.icio.us     Digg this     reddit!