Re: TECH: wireless gets real

From: Eugene Leitl (
Date: Tue Jul 10 2001 - 04:00:26 MDT

On Mon, 9 Jul 2001, Ken Clements wrote:

> Be very careful about using geographic data for wireless routing.

I will.

> Plenty of folks have done this in the past and been sorry. You can

That doesn't surprise me in the least. It's too early yet. If you're too
early, you get burned.

> get pointers by asking Google for "wireless geographic routing."
> Also have a look at my post:


> Geographic routing works well in places where the physical space maps
> well into the communication link space (Kansas) and is problematic

Of course, it's the prerequisite. That's why I mentioned cellular
wireless, which is orderly as if taken from Christaller.

> when it does not (Manhattan). The shortest physical distance may not
> be the shortest latency. Wireless links are stochastic. Just because

Sure, we don't live in a perfect world. But the point is not to choose the
best possible link (it will come later, when the connectivity map will
resemble the physical map, and routers will measure relativistic signal
TOF latency), the point is to have a progress metric, so you can chuck out
monster routing tables, and overwhelming admin traffic.

> you got a packet through a link quickly this time, does not mean you
> will be able to do so next time. Often the best route in

Yes, ATM did it better. As I said, IP is b0rken.

> communication space looks very strange when you see it represented on
> a map.

If you use cut-through, you can measure the line length inbetween.

-- Eugen* Leitl <a href="">leitl</a>
ICBMTO : N48 10'07'' E011 33'53''
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