Internet Protocol Version 6 (IPv6) is a new suite of standard protocols for the network layer of the Internet defined by IETF to replace the current version of Internet Protocol version 4 (IPv4). IPv6 is also called as Next Generation Internet Protocol or IPng.
IPv6 is designed to be an evolutionary step from IPv4. It is a natural increment to IPv4. It can be installed as a normal software upgrade in internet devices and is interoperable with the current IPv4. Its deployment strategy is designed to not have any flag days or other dependencies. IPv6 is designed to run well on high performance networks (e.g. Gigabit Ethernet, OC-12, ATM, etc.) and at the same time still be efficient for low bandwidth networks (e.g. wireless). In addition, it provides a platform for new internet functionality that will be required in the near future.
IPv6 describes rules for three types of addressing: unicast (one host to one other host), anycast (one host to the nearest of multiple hosts), and multicast (one host to multiple hosts). Additional advantages of IPv6 are:
- Options are specified in an extension to the header that is examined only at the destination, thus speeding up overall network performance.
- The introduction of an "anycast" address provides the possibility of sending a message to the nearest of several possible gateway hosts with the idea that any one of them can manage the forwarding of the packet to others. Anycast messages can be used to update routing tables along the line.
- Packets can be identified as belonging to a particular "flow" so that packets that are part of a multimedia presentation that needs to arrive in "real time" can be provided a higher quality-of-service relative to other customers.
- The IPv6 header now includes extensions that allow a packet to specify a mechanism for authenticating its origin, for ensuring data integrity, and for ensuring privacy.
IPv6 Features:
- New header format
- Large address space
- Efficient and hierarchical addressing and faster routing infrastructure
- Stateless and stateful address configuration
- Mobile support (Mobile IPv6)
- Built-in network layer security
- Better support for QoS
- New protocol for neighboring node interaction
- Extensibility
Addressing Format :
An IPv4 address is a 32-bit value that's usually written in "dotted quad" representation, where each "quad" represents a byte value between 0 and 255, for example:
127.0.0.1
This allows a theoretical number of 2^32 or ~4 billion hosts to be connected on the Internet. Due to grouping, not all addresses are available today.
IPv6 addresses use 128-bit technology, which results in 2^128 theoretically addressable hosts. This allows a really big number of machines to be addressed, and it will fit all today's requirements plus PDAs, cell phones, and even IP phones in the near future without any sweat. When writing IPv6 addresses, they are usually divided into groups of 16 bits written as four hex digits, and the groups are separated by colons. An example is:
fe80::2a0:d2ff:fea5:e9f5
This shows a special thing -- a number of consecutive zeros can be abbreviated by a single "::" once in the v6 number. The above address is thus equivalent to fe80:0:00:000:2a0:d2ff:fea5:e9f5 -- leading zeros within groups can be omitted.
Mobile IPv6:
Mobile IPv6 allows an IPv6 node to be mobile - to arbitrarily change its location on an IPv6 network - and still maintain existing connections. When an IPv6 node changes its location, it might also change its link. When an IPv6 node changes its link, its IPv6 address might also change in order to maintain connectivity. There are mechanisms to allow for the change in addresses when moving to a different link, such as stateful and stateless address autoconfiguration for IPv6. However, when the address changes, the existing connections of the mobile node that are using the address assigned from the previously connected link cannot be maintained and are ungracefully terminated. The key benefit of Mobile IPv6 is that even though the mobile node changes locations and addresses, the existing connections through which the mobile node is communicating are maintained.