IPv6 is the replacement Internet Protocol for IPv4. Its vastly expanded address space solves depletion issues and removes the need for NAT, restoring the original “flat” addressing concept of the Internet.

The designers of IPv6 not only increased address space, but decided to tackle problems encountered in IPv4. IPv6 boasts new features such as address auto-configuration (replacing much of the functionality of DHCP), built-in security using IPSEC, enhanced QoS support, better address scoping in unicast, better multicast capability, restores end-to-end connectivity (good for many peer-to-peer applications), and better support for mobile IPs.

IPv6 addresses are written in eight groups of four hexadecimal digits with groups separated by a colon. A group of zeros can be replaced by a single zero, and leading zeros can also be dropped. Consecutive groups of zeros can be replaced by a double colon (but this can only be done once within a single address). For example, the addresses fe80:0000:0000:0000:0000:ffff:ffff:fffd, and fe80:0:0:0:0 :ffff:ffff:fffd, and fe80::ffff:ffff:fffd are equivalent.

Since IPv6 removes the need for NAT, network administrators should plan security arrangement accordingly. IPv6 restores end-to-end communication between nodes, which will no longer be using private IP addresses hidden behind a public gateway as in the case of NAT.