as something to be gained by centralizing it in a monolithic switch because that allowed consumers to access the network and to participate as users with a very low entry point. Until recently, if you wanted to spend time on the Internet, you had to have a PC, and a PC costs considerably more than a single-line telephone. On the other hand, costs are dropping in electronics and appliances all the time, so this is also becoming less of an issue, and perhaps in this way, too, distributing intelligence makes sense. This is the age-old argument about smart core/dumb edge versus dumb core/smart edge, and it speaks to the differences in philosophies between classic telecommunications engineers (affectionately referred to as "bell heads") and modern-day data communications engineers "net heads"). The semi- nal paper that gave rise to this argument, "The Rise of the Stupid Network," is an excellent resource and can be found at www.isen.com/stupid.html Chapter 10 talks more about the evolution of the intelligent edge. Packet Switching Whereas circuit switching was invented to facilitate voice telephony, packet switch- ing has its origin in data communications. In fact, packet switching was developed specifically as a solution for the communications implications of a form of data processing called interactive processing. The first generation of data processing was batch processing, in which a data entry clerk would sit down at a job entry terminal and key a volume of data onto Establishing Connections: Networking Modes and Switching Modes some medium-initially key punch cards, and later tape or disk. The data was preaccumulated on an intermediate medium, and at some later point, a job would be scheduled and a link would be established to the host that would be responsible for processing the data. When this preaccumulated volume was transmitted, it was a steady stream of continuous high-volume data, so batch processing made quite effective use of a circuit-switched environment. In contrast to batch processing, in interactiv