Hi mtnlady,
Well, Gilder has it all wrong on Cisco (shows my bias!).
A lot of discussion on this thread has centered on Cisco and the Fiber Optics threat. I would like to clear up a couple of misconceptions.
First, the term switching and routing gets thrown about as though they are functionally the same thing. They are not. Technically, switching is typically a layer 2 function, while routing is a layer 3 function. Let my explain.
NT, through their recent purchase, claims to have a photonic switch. While technical info. is incomplete at this point a few conclusions can be made about this device. Since it uses mirrors, it is likely more a digital cross connect, in that it can switch light streams, but no more. An exciting capability to be sure, and an important function, but this is not routing.
Routing, which is Cisco's forte, operates at layer 3. In english, that means that the router looks at each and every packet that reaches the router, looks at the destination address, then makes a decision on what port (circuit) to send the packet out on. Think of it like a letter. Each letter (packet) has a destination address and return address on the outside. Inside the letter is the data. Any fiber optic stream on a typical internet fiber circuit is composed of thousands of different packets, each with a unique and often different destination address. That is how you can communicate with one particular web site, while your neighbor communicates with another. You may both traverse the same fiber link out of the city, but you are ultimately destined for different web sites. As your packet travels to its destination, it may traverse several routers where your packet is transferred from one fiber optic cable to another until it reaches its final destination.
You can't individually switch millions of packets per second onto different paths using mirrors. In spite of the incredible strides made in photonics, nobody has come up with a way to break out each and every packet of a data stream to read the destination address, then make a routing decision -- all in pure photonics. This science still needs some significant breakthroughs before this is a reality.
The only way to do routing today is to break the F.O. stream down electrically. Not that photonics aren't important, and not that Cisco needs to get into this business at some point. However, nobody is making pure photonic routers today.
Long Cisco, no position in NT (but a great company)
Regards,
DN |
