 an entry in its routing tables to that effect, so that the next time a packet arrives with the same destination, the switch can consult its table and route the packet quickly. These routing protocols are analogous to the process of stopping and asking for directions on a road trip (or not), reputedly one of the great male-female differentiators-right after who controls the TV remote. Anthropologists must have a field day with this kind of stuff. According to apocryphal lore, women have no problem whatsoever stopping and 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 Chapter 2 asking for directions, while men are loathe to do it-one of those silly threats to the manhood things. Anyway, back to telecomm. If you were planning a road trip across the country, you could do so using one of two philosophies. You could go to AAA or a travel agent and have them plan out the entire route for you, or you could do the Jack Kerouac thing and simply get in the car and drive. Going to AAA seems to be the simplest option because, once the route is planned, all you have to do is follow the directions-Lewis's blazed trail, as it were. The downside is that if you make it as far as Scratch Ankle, Alabama (yes, it's a real place), and the road over which you are supposed to travel is closed, you are stuck-you have to stop and ask for directions anyway. The alternative is to simply get in the car, drive to the nearest gas sta- tion, and tell them that you are trying to get to Dime Box, Texas. The attendant will no doubt tell you the following: "I don't know where Dime Box is, but I know that Texas is down in the Southwest. So if you take this highway here to Kansas City, it'll get you closer. But you'll have to ask for better directions when you get there." The next gas station atten- dant may tell you, "Well, the quickest way to central Texas is along