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Just want to clarify the definition of terms here...

First of all, swithces and routers are different things, as ob1mike pointed out. The best explanation of the difference is one I heard in a post in FrozenCanuck's board a while back. Somebody there said it's best to think of a fork in a train track. If that fork were controlled by a switch, then it could send an entire train to one side, or to another. If that fork were controlled by a router, then the router could send each individual car in the train on whichever route it wanted to. It does this by examining data in the packets (i.e. the train cars) which give it directions. Since you can only read data electronically in the present day, doing this (optical routing) entirely in the optical will be a challenge that if/when overcome, will deserve a Nobel Prize, IMHO.

Optical switches, however, are more likely to be achieved in the near future. In the current SONET-based telecommunications system, fiber carries data from one local loop to another. Let's keep using the train metaphor. If I were taking Amtrak from New York to Los Angeles, I'd want to take an express. But the current telecommunications system means has some limitations. Mainly, light can only travel so far before needing to be regenerated (Corvis and Qtera [now part of Nortel] have been working on ultra-long haul, which will be explained shortly. Sycamore is also working on this, though they're probably a bit behind). So this means that the "light train" has to stop every few hundred miles, be converted into electricity, and then resent over fiber optics. Any data that branched off before L.A. was then sent whereever it was going, say Kansas City.

This was fine before light could be sent long distances without electrical regeneration. But now, as mentioned above, light can be sent (by Corvis, Nortel, and hopefully soon Sycamore) across the country all in the optical. Which, again, is fine if you're doing the New York to L.A. express route. But what if you want to get off at Kansas City? Either lay a whole separate railroad track there (dig new fiber--expensive!), or just make a "smart train station." This is where optical cross connects (OXC) come in. A special type of switch, an OXC can let data coming in over the long haul wires pass through entirely in the optical, while diverting local-bound traffic to the correct places. One with an electrical core, like Sycamore's converts the signals to electricity to do this. One with an optical core would not need to do this.

Check out Light Reading (, under Reports. They have an article called "optical illusions" which debunks many companies' claims of building an all optical cross connect. Evidently, only Lucent has built a true optical core cross connect, but its drawbacks are severe enough to make its utility questionable. Corvis has been telling everyone who will listen that they've built a true OXC, but like the Wizard of Oz, they keep shouting, "Pay no attention to the man behind the curtains, pulling all the levers." That is, they won't let anyone actually look at their box to see if it really is what they say it is.

The bottom line: the first company that actually builds an all-optical router that doesn't suffer from light degradation(as Lucent's does) will reap a huge windfall. Agilent thinks it can do this with inkjet printer bubbles, Lucent with microelctrical mirrors (MEMs), and others are investigating LCD technology. In the meantime, Sycamore seems to have a very capable opto-electrical OXC, backed up by what many consider to be among the best network management software in the industry. Hence intelligent optical networking.

Hope I got all this right!
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