Introduction to IPv6

At the time when the Internet was created, nobody predicted that it would become the de facto medium for business transactions, communication, shopping, and entertainment. The original ARPANET and NSFNET networks were created to facilitate communication between military personnel and educational institutions. The IPv4 protocol, specified in RFC 791, was standardized in 1981, and provided 32 bits of address space. As corporations and home users rapidly jumped on the ``information superhighway,'' it was clear that this implementation was not going to work. Within time, CIDR and NAT were developed to more efficiently utilize the IPv4 address space, but these were only short-term workarounds, not solutions. Additionally, with over 26% of the IPv4 allocations belonging to the United States, the world is definitely in need of a new protocol.

The IPv6 protocol, first standardized in RFC 1883 (now obsoleted by RFC 2460) and written in 1995, brings 128 bits of address space to the Internet, in addition to built-in multicast routing capabilities and privacy extensions. IPv6 headers are of a fixed length, with flexible extension headers replacing the need for variable header fields that were present in IPv4. Neighbor discovery and ICMPv6 replace ARP, IGMP, and router discovery, making it easier to locate and communicate with hosts sharing the same link.

Mark Kamichoff 2004-04-23