IPv6
Internet Protocol is a set of technical rules that defines how computers communicate over a network. There are currently two versions: IP version 4 (IPv4) and IP version 6 (IPv6).
IPv6 (Internet Protocol version 6) is the next generation protocol designed by the IETF (Internet Engineering Task Force). This replaces the current version Internet Protocol, IP Version 4 (IPv4). IPv6 is expected to gradually replace IPv4, with the two coexisting for many years during a transition period.
IPv4 versus IPv6
IPv4 was the first version of Internet Protocol to be widely used, and still accounts for most of today’s Internet traffic.
IPv6 is a replacement for IPv4. IPv6 was deployed in 1999 and provides far more IP addresses, which should meet the requirement well into the future.
Most of today's Internet uses IPv4. There is a growing shortage of IPv4 addresses, which are required by all new machines added to the Internet.
IPv6 fixes many problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as extended address space, auto-configuration, and others.
The major difference between IPv4 and IPv6 is the number of IP addresses. There are over 4 billion IPv4 addresses. In contrast, there are over 16 billion-billion IPv6 addresses. The technical functioning of the Internet remains the same in both versions. Most networks that use IPv6 support both IPv4 and IPv6 addresses in their networks.
In the system, two sockets are created: one for IPv4 and one for IPv6, both of which are handled separately.
Scope
There are three types of scope for the IPv6 unicast addresses:
- The link-local scope identifies all hosts within a single layer 2 domain. With this, two hosts on separate networks could have the same link-local address. For example, if host B is required to communicate with host A, the scoped IPv6 address "fe80::1%eth0" must be used.
- The site-local scope fits logically between the link-local and global scopes. A site can be a corporate network, a geographically constrained portion of a corporate network, or an administered domain within a corporate network. A site-local address is unique in the site.
- The global scope identifies all devices reachable across the Internet. Global unicast addresses are unique.