ATM to the desktop was the way of the future.

Right.

No-one rolled out ATM to the desktop. Everyone rolled out fast ethernet.

Why?

One: They already had ethernet. If you have ethernet, and it's slow, then the obvious solution is fast ethernet, right? Which is a large part of why 100BaseVG-AnyLAN died in the market. You can buy fast ethernet or... What was it again? 100BasicVB something? Let's just get some of that fast ethernet that everyone else is buying.

Two: Speed wins. Fast ethernet is 100mbits. ATM was being pushed for the desktop at 25mbits. 100 is more than 25. End of story.

Three: Price wins. Fast ethernet was cheaper.

Four: The price for ethernet switches fell through the floor. Suddenly, no-one in their right mind was using hubs. That 40% ceiling? Erased, utterly. Now you could not only safely hit 100%, you could safely exceed 100%, because different parts of your network were effectively on different circuits - all handled automatically.

That wiped out ATM's former big advantage - quality of service.

Let's say you had a network that was carrying both phone calls and data, such as terminal sessions to your accounting system. If your network gets full, you can't slow down the traffic on the phone calls, because then people won't be able to understand each other. But you can slow down the terminal sessions. It's annoying, but it still works. ATM looks after this for you.

On old-style ethernet, with a single network segment, once you started pushing too much traffic (and "too much" wasn't actually very much at all), everything would stop working. Both the phone calls and the terminal sessions would fail. (There was actually something called isochronous ethernet that ran 96 ISDN B-channels alongside standard 10mbit ethernet, so as to carry voice and data at the same time. It died.)

On new, switched, fast ethernet, it simply wasn't a problem. The phone calls and the terminal sessions weren't competing for scarce bandwidth anymore, because (a) they were put on different circuits, and (b) bandwidth wasn't scarce.

And ATM dropped dead, as far as computer networks go. The phone companies still haven't worked this out.

Right now, I can buy a 48-port gigabit stackable layer 3 managed network switch and 48 gigabit ethernet cards for the same price as one 155mbit ATM module from Cisco. Which way would you go?

And when you come to upgrade your gigabit ethernet, would you choose 10-gigabit ethernet, or... That other thing?

Posted by: Pixy Misa at 09:51 AM | Comments (2) | Add Comment | Trackbacks (Suck)
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