IP Addressing and Subnetting Including IPv6
A clear, comprehensive guide to IP addressing, including technical details on IP message formats and standards.
TABLE OF CONTENTS IP Addressing and Subnetting Including IPv6
What Are the Advantages?
If you've read the previous sections in this chapter, you probably already have a pretty good idea of the advantages of using NAT. Primarily, it allows you to use a relatively small number of public IP addresses to connect a large number of inside machines to the Internet. It also buys you some flexibility in how you connect to other networks.
For Managers: How Many IP Addresses Do You Really Need?
There are many more Internet connectivity options available today than there were just a short while ago. These include modems, ISDN, traditional leased-line, DSL, cable, wireless, and more. Prices, performance, reliability, and availability vary widely, but they all have one feature in common: The more IP addresses you want, the more expensive it will be. From a financial perspective, it makes sense to get by with as few as possible. NAT can go a long way towards reducing the number of IP addresses needed. PAT can be used in most cases to let all your internal machines access the Internet as if they were one IP address. This can be crucial if the access technology only allows for one IP address, such as dial-up access (modem, ISDN). If you plan to host any publicly accessible services on your premise, such as a Web server or DNS server, you'll need a few more IP addresses. This usually isn't too much of a problem, since dial-up access isn't appropriate for hosting public servers anyway. You can still...
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