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.

F I G U R E   1 .   N e t w o r k   N u m b e r   G ro w t h

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