The original IP version 4 protocol, specified by RFC 760 in January 1980, was replaced by RFC 791 in September 1981. IP version 6 was originally specified by RFC 1883 in December 1995. Presently, IP version 6 uses the RFC 2460 specification. IP version 6 was therefore referred to as IP the Next Generation (IPng).
Although the IP version 4 was robust at the time of its publication in 1981, it did not anticipate several Internet advances including:
- The recent exponential growth of the Internet and the impending exhaustion of the IP version 4 address space
- The need for simpler configuration
- The requirement for security at the IP level
- The need for better support for real-time delivery of data, also called quality of service
IP version 6 has not only enlarged the IP address size from 4 to 16 bytes, but also offers a revamped view of the IP datagram. Fields such as the header checksum as well as other infrequently used fields are now optional rather than mandatory...