IPv6 is the next version of IP from IPv4 and is the most recent version of the Internet Protocol. The most important improvement in IPv6 is that it provides a large address space and has auto- configuration that overcomes most of the shortcomings of IPv4. It has integrated security and mobility features.
IPv6 has a simplified header, fast forwarding, enhanced priority support and a smooth transition. It supports 3 addressing modes:
- Unicast- A host addressing another unique host in the network.
- Multicast- A host or a server addressing a group of hosts in the network.
- Anycast- It is new mode of communication introduced in IPv6. Multiple servers might be assigned with the same anycast IP and the host trying to contact for the service will be connected to the nearest server having the same any cast IP.
IPv6 is a 128 bit hexadecimal address. It will be divided into eight 16 bit blocks and each block is then converted into 4- digit hexadecimal numbers and are separated by colon. The 128 bit address is nothing but a combination of two 64 bit addresses and are termed as Host ID (Interface Id ) and Network Id. The Interface Id is Auto Generated. There are three Address Scopes in IPv6: Global Unicast address, Unique Local Unicast address and Link Local address.
The transition from IPv4 to IPv6 is possible with few techniques such as Dual Stack Routing, Tunneling and NAPT (Network Address Protocol Translation). In Tunneling, if different IP versions exist in an intermediate path, the user’s data could pass through a non- supporting IP version. A Dual Stack Routing is where a router is installed with IPv4 stack and IPv6 stack so that it can forward both the type of packets. The Routing protocols used in IPv6 are Distance Vector Routing Protocol and Link- State Routing Protocol.
IPv6 can’t completely replace IPv4 i.e. both the networks need to co- exist.