The FreeBSD Corporate Networker's GuideCIDR MissingA reviewer stated that discussion and use of CIDR notation was called for, as well as addressing the issue of whacked-out routing on the Internet was getting due to the mis-assignment of IP numbers in IPv4. It is true that routing on the Internet today is very difficult, primarily due to handing out things like entire class A addresses to single organizations way back in the beginning. The truth is that what can be read in the trade rags about a shortage of IP numbers is untrue. There is no real shortage; it's just very bad assignment. The situation on the Internet today is analogous to this hypothetical situation: Say if in the early days, the United States Postal Service had given every single house a different ZIP code. Then, after most of the numbers in the range of ZIP codes were used up in the 13 colonies, Congress suddenly mandates, "Now you've got to deliver mail to an additional 10 states that have triple the population that the 13 colonies had." So, then the USPS starts using one ZIP code per street. Then five years later the same thing happens and they start using one ZIP code per city. But, each house in the original 13 colonies _still_ has its individual ZIP code. In that case, there would be a terrific shortage of ZIP codes in the new part of the country, and a tremendous oversupply of them in another, and none of the people in the old part of the country would want to give theirs up because their friends would all have to change their address books! This is exactly what is happening today with IPv4 on the Internet. Indeed, some of the impetus for IPv6 is that, if it gets implemented, it would force everyone to renumber, and the engineers could then get a chance to do everything over again properly. Anyway, while I talk about why this situation is messed up in the book, I don't go into how exactly it is screwing up routing on the Internet because it would take almost another chapter to properly explain, and I didn't feel that it should be included in the first edition of the Networker's Guide. As far as using CIDR notation, I agree with it, but even FreeBSD itself still doesen't completely use it. Look at the IP address entry screens in the sysinstall installation utility that the admin uses to assign the initial IP numbers to the system, for example. CIDR is difficult for the newbie to TCP/IP to understand, especially if they have already swallowed a lot of improper instruction on TCP/IP anyway. It's worth it to note that even the Microsoft MCSE instructional materials on TCP/IP are only just going to be starting in with CIDR and classless addressing in 2001. For another example, there are still routers today made that don't use CIDR. Such routers include Cisco, and LinkSys, although the very latest IOS from Cisco now apparently supports CIDR notation.
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