Communication at the network layer is host-to-host (computer-to-computer). A computer somewhere in the world needs to communicate with another computer somewhere else in the world. For this communication, we need a global addressing scheme, called “logical. addressing”.
Today, IP addresses are used to provide logical addresses in the network layer of the TCP/IP protocol suite.
IPV4 -The Internet addresses are 32 bits in length; this gives us a maximum of 2^32 addresses.
The need for more addresses, in addition to other concerns about the IP layer, motivated a new design of the IP layer called the new generation of IP or IPv6 (IP version 6). In this version, the Internet addresses are 128 bits in length; this gives us a maximum of 2^128 addresses. 128-bit addresses give much greater flexibility in address allocation. These addresses are referred to as IPv6 (IP version 6) addresses.