Slashdot Mirror
The 1st Commercial-Grade All-Optical Switch?
joabj writes: "Today's Washington Post trumpeted the delivery of the first-ever commercial-grade optic-switch, by Corvis Corp. I'm not sure how commercially viable a switch the size of a refrigerator can be, though a commercial-grade all-photonic switch is indeed, as the WP points out, a "holy grail" of the optics industry--the missing piece for the 40-80 Gbps throughput for fiber optic cable that the industry is so hungering for these days. (Now, photonic signals must be converted into electrical signals to be switched, then back into light again -- slowing transmission speeds considerably.) Unfortunately neither the article (Free reg. req.) nor Corvis' own
Web site explains what the winning technology was. There are a lot of competing ideas out there
on how to switch optical signals. Is it MEMs? Liquid crystals? Curious minds want to know ..."
Initially, this sounds a lot like the optical switch announced by Agilent a little while ago, but with the bonus of being ready "within a few weeks" from workaday life. (Does that mean the equipment reported as delivered is still being installed or set up?) [Updated 11th Oct. 2000 4:05 GMT by timothy:] As a few people have pointed out in comments, that free registration is pretty painless ... since it's not necessary. Better than the other way around! ;)
"one treats others with courtesy not because they are gentlemen or gentlewomen, but because you are" --G. Henrichs
Personally, I take announcements of prototypes such as those above with a grain of salt. A prototype is still further away from production than most people realize. You can pretty much do anything you want within the limits of physics, given a big enough R&D budget (and snazzy enough PR department to tout your work). But for your prototype to A: work *all* the time in the field, B: and for a competitive price, and C: to be compatable with existing standards, are the hurdles that kills 99.5% of all new technologies. . . joab
This area of technology is so full of hype and marketing lingo it is hard to sort fact from fiction. Are they first? So what tomorrow someone else will be second with bigger this or that. I would not attach too much importance to the fact that a reporter got duped in to believing this was the "holy grail".
But it is so interesting that optical switching has become the rock star of the day. Because essentially these are very low intelligence switches that perform very cool optical tricks. These devices are essentially circuit switched devices. But even that is probably too much credit they are static circuit switched devices. Because optical paths are setup by a network administrator. An IP router or carrier voice switch are far more intelligent then one of these devices. No one gets excited about add/drop muxes anymore but I am sure in their day it was big deal. Add/drop muxes became a commodity, just as optical switches probably will become some day. These devices, along with IP routers, ATM switches, ethernet switches, sonet muxes, dwdm, etc... are low glamor working class equipment of the carriers networks.
The most interesting part is the ability split out or splice in individual wavelengths, neat trick.
One big issue with these optical switches is that they don't switch packets, they make persistent connections like a phone call. So optical data passes through cleanly, to ONE place. So this doesn't accomplish the function of a network switch at all. They're electronically controlled, so it's a lot better than manually re-routing a fiber patch panel, but that's all they do.
Be sure to check out this article in Wired from a few months back about using porous crystals to do an all-optical switch that is also solid state. Apparently older models used thousands of little rotating mirrors! The same technology can be used for regulating other kinds of waves including sound waves and wave waves (like in the ocean).
An article at http://www.ciena.com/news/archive/2000/07/07.19.20 00pr.html explains how CIENA has already filed against Corvis charging that Corvis violated 3 patents relating to CIENA's optical networking communications systems and technology.
How this will effect the switch is unknown as of yet.
Corvis's switch is an all-optical switch. No eletrical regeneration involved. What it is switching is wavelengths of light. NOT packets. So, you can take a wavelength of light from one fiber and send it out another. This allows you to set up 2.5Gbps (OC-48) circuits quickly.
What technology are they using - don't won't say. Almost all other people in this arena are basically splitting the dense-wave-division-multiplexed (DWDM) circuits into their individual wavelengths. Then routing them through micro-mirrors. The micro-mirrors allow you to connect any two fibers together optically. Then, the outputs from this are re-combined, optically amplified and transmitted.
This isn't for sure what Corvis is doing - but I would bet money that this is basically what they are doing.
One problem with this is that you can't have two circuits on a fiber using the same wavelength of light. So, you would need something that shifts the wavelength of light being used. Nobody that I know of has a commercial product to do this.
Press blurb about this particular thing is available in a Light Reading article.
A couple of weeks ago, Corvis announced that they had revenue - from this shipment of course.
One more link - Some hints to what technology they are using.
It occurred to me that the O->E conversion may be skipped entirely if the O data is encoded in such a way that the 'header' can be read without doing some sort of fancy decoding, interpretation, then switching.
Of course, this brings an optical switch into the realm of analog computing, instead of digital, but hey...
Dunno if this is even possible inside of a fiber, but can one encode a holographic signal into the header? This depends on the signal being coherent in the fiber, but if you can take the signal and recombine it with a similarly coherent signal, you can get data out. This data is still optical, perhaps in the form of a grid pattern(barcode here!) which can be read and interpreted. At this point it would seem an electrical device is still needed to operate the switch...
I dunno, how do they really encode this information? Just binary pulse data?
The nick is a joke! Really!
GPL Deconstructed
I believe this works, not by using a header to assign an address, but by assigning a freqency to a destination and that frequency is then switched optically.
The first switch reads the header and assigns the frequency, then the subsequent switches simply switch based on frequency (never reading the content of the packet). Then the last switch, (who owns that frequency) then converts it to electricity and sends it over the regular network (i.e. like ethernet...)
One day, we will all be assigned frequencies like we are assigned IP addresses and all info will be transported by fiber.
This is just pure stock ramping. I wish it was true as I have some friends at Corvis, unfortunatly, the switch is a long way off. Management wanted to release this PR after a concept trial that was sucessful, this switch is at least 5 months way from market + it's NOT all optical as headers are converted to good old fashioned electrial signals, the switching path is determined and then the packet is switched via MEMS tech.
Lucent is the closest to an all optical switch followed (a fair way back) by an English company call goouch and housego (I think the spelling is slightly off there).