Version 6 of the internet protocol, which will replace version 4.
Internet Protocol version 6 (IPv6) is the successor to the well known IPv4 protocol, commonly known as IP. Your Ubuntu system comes with all you will need to use IPv6.
In the early 1990s, growth of the Internet led to various problems with IPv4, including:
- Running out of subnets. This was deferred by conversion to Classless Inter-Domain Routing (CIDR), currently described by RFC4632
- Running out of addresses. This was deferred by using RFC1918 private address space (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) hiding behind Network Address Translation (NAT) devices, in which a single public IPv4 address can be shared by multiple computers, e.g. all the users connected through a DSL/Cable modem. But NAT has its own problems. Besides NAT, in some cases during the transition to IPv6, multiple internet connections will share IPv4 addresses via dual-stack-lite. And as of 2011, a growing number of nodes on the Internet only speak IPv6 since unassigned IPv4 addresses started to run out.
- Routing table were getting too large. This is still a concern today.
IPv6 deals with these and many other issues:
- 128 bit address space, with a design goal of supporting 240 subnets organizing 250 hosts. While theoretically there are 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses possible, this is unattainable in practice. IPv6 does offer multitudes of addresses per person, so we are unlikely to run out again.
- Each computer can have it's own globally routable address. There is no need for NAT in IPv6, returning us an architecture more similar to the peer-to-peer internet of the 1980's.
- Smaller routing tables. Due to both better geographic and more hierarchical allocation strategies, IPv6 subnets currently generate only 1/7th as many routes as IPv4 subnets.
There are also lots of other useful features of IPv6 such as:
- Address autoconfiguration (RFC2462)
- Anycast addresses (“one-out-of many”)
- Mandatory multicast addresses
- IPsec (IP security)
- Simplified header structure
- Mobile IP
- IPv6-to-IPv4 transition mechanisms
--From Ubuntu Wiki, which is licensenced CC-BY-SA
