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To: Ray Smith Jr who wrote (3988)	6/1/1999 5:56:00 PM
From: Frank A. Coluccio	Respond to of 12823

Ray, Re: "Wavelength routing is a marketing term for the same optical switching IMO." Up until recently, I would have agreed with you fully. I.e. optical switching supported by optical cross connects, or OCCs, like those made by Tellabs. And other switching approaches in the way of optical add-drop multiplexers, or OADMs, made by DWDM vendors. But with the introduction of new optical layer "protocols," which I prefer to think of as 'processes,' like Monterey Network System's (MNS) Wavelength Routing Protocol, or WaRP, and with the imminent prospects of others doing the same thing (Corvis, being one of them, but we wont fully know until they unveil their wares later this month) the distinctions may be widening between what have been referred to as optical switching, and optical routing. Permit me to explain, briefly, what one player is doing in this space to achieve optical, or as they call it, wavelength, routing. When you examine what it is that Monterey is doing, it becomes clear that they are actually using multi-Gigabit routers and optical mappers to perform what they are calling wavelength routing. The multi-Gb routers, which reside in their architecture, segregate and organize packets, assign headers, perform lookups, etc., just as any ordinary router would do (albeit, at ultra-high speeds). In turn, the second stage consists of accepting those packets and mapping them directly to their appropriate wavelength-defined paths (which actually can be viewed as taking the place of ATM's permanent virtual circuits), at silicon speeds. In so doing, they've avoided the need for using Layer 1 SONET, and Layer 2 ATM. To some extent they are borrowing from some old terminology to describe new capabilities. But if it works as advertised, then they can call it whatever they want, and more power to them. What they've achieved, effectively, is optical layer routing. Regards, Frank Coluccio

To: Ray Smith Jr who wrote (3988)	6/2/1999 7:21:00 AM
From: Frank A. Coluccio	Respond to of 12823

Ray, perhaps for the sake of brevity I was overly general in my reply to you in Post # . For one thing, I should have referred to the first stage of Gb "routing" more appropriately as Gb switching, working in tandem with a secondary routing function. Also, I didn't adequately address the optical underpinnings of the MNS model. The wavelength paths are not fixed, as I might have led you or others to infer. I.e., they are more like ATM switched virtual paths, which can be reconfigured at sub-50 ms speeds between router pairs, and beyond. This means than a continuos, made-to-order, multi-node end to end path (or partial core path) can be established at the optical layer at SONET Ring-restoration-like speeds, to facilitate both normal route adaptations and recovery schemes. At present, these wavelength-level route builds (virtual wavelength paths) are facilitated by... you guessed it... fast optical cross connects, or the OCCs for the most part, which we discussed earlier. The OCC fabric also resides within each "router" node. Not only can this virtual wavelength path be created in a basic network topology, but traffic buildup may require multiple streams which in turn may justify the creation of additional dynamically configured virtual wavelength paths, on the fly, as well. Again, this is overly simplistic, but I think it more accurately characterizes what NMS and others are now doing in the space coming to be known as wavelength routing. It'll get better, more organic and optically pure, as time goes by. For now, however, this is what we have. Regards, Frank Coluccio