6.1 Network: First Period of History
This era lasted from the beginning of the Internet until 1993. In this era, the term ‘net’ was specified by RFC 796 standard (J. Postel, September 1, 1981). Those twelve years were marked by the idea that 4 bytes must be enough for an IP address.
An IP address was structured into a network address and a computer address within a network, as is shown in the following figure:
Figure 6.1: Structure of an IP address
It is the initial bits of the first byte of an IP address that determine how many bytes of the IP address make up the network address. There are five classes of IP address:
- Class A: The value of the highest bit of the first byte is 0. The remaining 7 bits of the first byte represent the network address and the rest (24 bits) are reserved for the computer address within the network. There are 126 networks within the A Class (0 and 127 are networks with a specific meaning). In each network there are 224-2 computer addresses (addresses...