Understanding IP Addressing:
Everything You Ever Wanted To Know
The Internet continues to grow at a phenomenal rate. This is reflected in
the tremendous popularity of the World Wide Web (WWW), the opportu-
nities that businesses see in reaching customers from virtual storefronts,
and the emergence of new ways of doing business. It is clear that expanding
business and public awareness will continue to increase demand for access
to resources on the Internet.
Internet Scaling Problems
Over the past few years, the Internet has experienced two major scaling
issues as it has struggled to provide continuous and uninterrupted
growth:
• The eventual exhaustion of IP version 4 (IPv4) address space
• The need to route traffic between the ever increasing number of net-
works that comprise the Internet
The first problem is concerned with the eventual depletion of the IP
address space. IPv4 defines a 32-bit address which means that there are
only 232 (4,294,967,296) IPv4 addresses available. As the Internet con-
tinues to grow, this finite number of IP addresses will eventually be
exhausted.
The address shortage problem is aggravated by the fact that portions of
the IP address space have not been efficiently allocated. Also, the tradi-
tional model of classful addressing does not allow the address space to
be used to its maximum potential. The Address Lifetime Expectancy
(ALE) Working Group of the Internet Engineering Task Force (IETF) has
expressed concerns that if the current address allocation policies are not
modified, the Internet will experience a near to medium term exhaus-
tion of its unallocated address pool. If the Internet’s address supply
problem is not solved, new users may be unable to connect to the global
Internet. More than half of all possible IPv4 addresses have been
assigned to ISPs, corporations, and government agencies, but only an
estimated 69 million addresses are actually in use.
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FIGURE 1. Network Number Growth
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