The Key West connection

A recent trip to Key West to explore the coral reefs turned out to be a living allegory for network engineering. The real travel time from our house in New Jersey to the reef is 3 hours; it took all day. Our packet of 3 person bytes traveled in a variety of cells, each the appropriate size to get the best efficiency for its technology. We employed cars, busses, a monorail, a jet plane, a propeller plane, a boat and, of course, shoe leather. Each was optimally efficient for its portion of the journey, but the gathering of status information at each juncture caused queuing delays that were in total greater than the actual travel time. Properly labeled though, we did arrive eventually at our destination, intact and reassembled with our bags, a minor miracle considering the mixed lot of destinations and purposes we encountered among our fellow travelers. Without straining this analogy too much, we can see parallels to the way Synchronous Optical Network (SONET) and Asynchronous Transfer Mode (ATM) are complimentary. SONETs great strength is that is makes the transport reliable. It is the modem, sale jet that makes the whole trip possible. ATM is the complete communications view that takes reliable transport of bits as a given and proceeds to work the problem of applications talking to each other. The flaw in the past has been that simple, robust ATM technology could not be used because the quality of the transport was poor, requiring error correction at each juncture. With SONET in place for a transition period, it is possible to execute Fraser's original idea of super fast transport of multimedia in fixed size cells [11. Everyone likes to feel that his creation is for all time, but SONETs true worth is as a transition tool. Once a SONET system is in place, an ATM control can encapsulate its network management functions so the separate overhead channels need no longer be dedicated to this. Its pipeline, reliable and fast, stays put and is transparent. The most sensible progression to introducing such complex technology is in steps: SONET, then SONET with an ATM overlay for a period of 5 to 8 years, then a welt-proven ATM network. All the technologies we can now name are temporary, including ATM. The next step is in