d by his company, Automatic Electric. Strowger's story is worth telling because it illustrates the serendipity that characterized SO much of this industry's development. It seems that Almon Strowger was not an inventor, nor was he a telephone person. He was, in fact, an undertaker in a small town in Missouri. One day, he came to the realization that his business was (OK, I won't say dying) declining, and upon closer investigation determined that the town's operator was married to his competitor! As a result, any calls that came in for the undertaker naturally went to her husband-and not to Strowger. To equalize the playing field, Strowger called upon his considerable talents as a tinkerer and designed a mechanical switch and dial tele- phone, which is still in use today in a number of developing countries. The bottom line to all this is that switches create temporary end-to- end paths between two or more devices that wish to communicate with each other. They do it in a variety of ways; circuit-switched networks cre- ate a "virtually dedicated path" between the two end points and offer con- stant end-to-end delay, making them acceptable for delay-sensitive Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Protocols Protocols applications or connections with long hold times. Store-and-forward net- works, particularly packet networks, work well for short, bursty mes- sages with minimal delay sensitivity. To manage all this, however, is more complicated than it would seem at first blush. First of all, the switches must have the ability to select not only a path, but also the best path, based on QoS parameters. This con- stitutes intelligent routing. Second, they should have some way of moni- toring the network so that they always know its current operational conditions. Finally, should they encounter unavoidable congestion, the switches should hav