Interesting People mailing list archives

IP: RE: SEE THE LIGHT BOUNCE: Edupage, March 26, 2001


From: David Farber <dave () farber net>
Date: Tue, 27 Mar 2001 06:33:49 -0500



John,

The real question on the table is : is packet switching at all rational in 
the all optical networks of the future. My estimate is the answer is no. A 
long time ago Len Kleinrock and myself independently wrote articles 
strongly suggesting that the nature of very high speed networks was not 
friendly to TCP/IP and the nature of optics is not, in my opinion , 
friendly to conventional packet switching.

Dave

At 05:59 PM 3/26/2001 -0800, you wrote:
From: John Shoch <shoch () alloyventures com>
To: "'farber () cis upenn edu'" <farber () cis upenn edu>

Well, let's not get completely buried by the hype...

--I hope everyone understands that the "current generation of switches"
described here is (I presume) the electro-mechanical switches used to
reconfigure optical links.  The "all optical" MEMS and bubble systems have
switching times which make them useful for configuring and reconfiguring
optical links, but they do not switch at rates which allow them to become
real-time packet switches.  Thus, they will not displace real packet routers
from Cisco, Juniper, et al.
--In-line signal conversion may add expense, but it does not (by itself) add
congestion.  Optical signals can be amplified, but over time, and distance,
the signal degrades.  Optical signals passing through optical switches will,
in many cases, eventually have to be re-generated -- which will still be
done by going through an O-E-O (optical-electronic-optical) conversion.

John Shoch
Alloy Ventures




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