Although the current version of IP has worked well for many years, exponential growth of the Internet means that the 32-bit address space will be exhausted within 20 years. The IETF has designed a new version of IP that uses 128 bits to represent each address. The new address space is so large that it will not be exhausted for many decades to come.
To distinguish the new version of IP from the current version, the two protocols are named using their version number. The current version of IP is IPv4 and the new expected version is IPv6. IPv6 retains many of the concepts from IPv4, but changes all the details. For example like IPv4, IPv6 provides a connectionless service in which two computers exchange short messages called datagrams. However, unlike an IPv4 datagram in which the header contains fields for each function, IPv6 defines separate headers for each function. Each IPv6 datagram consists of a base header followed by zero or more extension headers, followed by data.
Like IPv4, IPv6 defines an address for each network connection. Thus, as in IPv4, a computer that connects to multiple physical networks (e.g., a router) has multiple addresses. However special addresses are completely changed in IPv6. Instead of IPv4's notion of network broadcast, IPv6 defines multicast and anycast (cluster) addresses, both of which correspond to a set of computers. A multicast address corresponds to a set of computers at multiple sites that are treated as single entity; each computer in that set will receive a copy of any datagram sent to the set. A cluster permits replication of services; a datagram sent to a cluster address will be delivered to exactly one member of the cluster.
To make IPv6 addresses easier for people to use, the designers propose using colon hexadecimal notation, which expresses groups of 16 bits in hexadecimal, with a colon separating groups. The resulting notation is more compact than the dotted decimal form used in IPv4.
Today about 6 billion people inhabit the earth. They own an estimated 350 million computers and 480 million mobile phones. The number of mobile phones and PDAs is expected to reach one billion by 2003. The reason we are quickly moving beyond the capabilities of the current protocol has a lot to do with the propagation of wireless devices and new services, as well as the subsequent of massive demand for more addressees.
The very concept of computers is changing rapidly as cars, vending machines and even house hold applications follow the lead of the PC and become connected to the Internet. Each one will require its own unique address. It is estimated that within seven to ten years a single user will manage an average of 10 addresses and this number could grow higher in future. Wireless gambling, music on demand, video content and video conferencing are becoming a reality. With IPv6 every person on earth could have a million uniquely addressees and the individually locatable IP devices. With this kind of capability we could create the potential for virtually unlimited access to the Internet for variety of devises. (Techiwarehouse)
Some of the benefits of IPv6 seem obvious: greater addressing space, built-in QoS, and better routing performance and services. However, a number of barriers