IP Address Structure

An IP address contains a network part and a host part, but the format of these parts is not the same in every IP address. The number of address bits used to identify the network, and the number used to identify the host, vary according to the class of the address. The three main classes are class A, class B, and class C. The first few bits of an address will indicate the address' class.

Below: Class A Address

0nnnnnn 26	104	0	19
8 network bits	24 host bits

Below: Class B Address

10nnnnnn 128	66	12	1
16 network bits		16 host bits

Below: Class C Address

110nnnnn 192	178	16	1
24 network bits			8 host bits

The IP address provides addresses for everyone on the internet. When you connect to internet provider you are dynamically assigned an IP address for that session. However, some people do pay more for their own static IP address.

The design of the IP address that is shown above has some problems. That design favors routers over growth in number of host. For example, assigning a large corporate network a single B class address instead of several class C addresses reduces the load on the router (only one route is necessary). However, the large corporate network probably doesn't need the capability to address 64,000 computers that comes with the class B address. Another problem is depletion of addresses. Fuller, Li, Yu and Varadhan predicted in 1992 that all class B addresses will be exhausted by 2007. Most solutions to address depletion cause routing tables to grow to an unacceptable size. Industry tasks force groups are now working on the problems. The optimal solution to the problems mentioned above will probably be a new or modified internet protocol.