Internet Protocol Version 6 (IPv6) is a network layer protocol that enables data communications over a packet switched network. Packet switching involves the sending and receiving of data in packets between two nodes in a network. The working standard for the IPv6 protocol was published by the Internet Engineering Task Force (IETF) in 1998. The IETF specification for IPv6 is RFC 2460. IPv6 was intended to replace the widely used Internet Protocol Version 4 (IPv4) that is considered the backbone of the modern Internet. IPv6 is often referred to as the "next generation Internet" because of its expanded capabilities and its growth through recent large scale deployments. In 2004, Japan and Korea were acknowledged as having the first public deployments of IPv6.
The explosive growth in mobile devices including mobile phones, notebook computers, and wireless handheld devices has created a need for additional blocks of IP addresses. IPv4 currently supports a maximum of approximately 4.3 billion unique IP addresses. IPv6 supports a theoretical maximum of 2128 addresses (340,282,366,920,938,463,463,374,607,431,768,211,456 to be exact!). Recent advancements in network technology including Network Address Translation (NAT) have temporarily lessened the urgency for new IP addresses, however, recent estimates indicate that IPv4 addresses could be exhausted as soon as 2012.
IPv6 and IPv4 share a similar architecture. The majority of transport layer protocols that function with IPv4 will also function with the IPv6 protocol. Most application layer protocols are expected to be interoperable with IPv6 as well, with the notable exception of File Transfer Protocol (FTP). FTP uses embedded network layer addresses to facilitate data transmission. An IPv6 address consists of eight groups of four hexadecimal digits. If a group consists of four zeros, the notation can be shortened using a colon to replace the zeros.
A main advantage of IPv6 is increased address space. The 128-bit length of IPv6 addresses is a significant gain over the 32-bit length of IPv4 addresses, allowing for an almost limitless number of unique IP addresses. The size of the IPv6 address space makes it less vulnerable to malicious activities such as IP scanning. IPv6 packets can support a larger payload than IPv4 packets resulting in increased throughput and transport efficiency.
A key enhancement over IPv4 is native support for mobile devices. IPv6 supports the Mobile IPv6 (MIPv6) protocol which enables mobile devices to switch between networks and receive a roaming notification regardless of physical location. MIPv6 is a hallmark of the protocol and was specified as a firm requirement during the design of IPv6. The IETF has separate specifications for MIPv6 that detail data structure, messaging, and security requirements.
Auto-configuration is another IPv6 enhancement that is considered a great benefit to network administrators. IPv6 devices can independently auto-configure themselves when connected with other IPv6 devices. Configuration tasks that can be carried out automatically include IP address assignment and device numbering. An IPv6 router has the ability to determine its own IPv6 address using data link layer addressing parameters. The IETF has issued RFC 2462 to set guidelines for IPv6 auto-configuration.
The IPv6 protocol improves upon IPv4 with increased authentication and privacy measures. IPSec security is embedded into the IPv6 specification to manage encryption and authentication between hosts. This built in security framework enables secure data traffic between hosts that is independent of any applications on either host. In this way, IPv6 provides an efficient end to end security framework for data transfer at the host or the network level.
The deployment of IPv6 networks is growing worldwide. Full replacement of IPv4 is expected to take some time, as it remains the most widely used Internet Protocol. The United States, China, and India are leading recent deployments of the IPv6 protocol and have large investments in IPv6 network infrastructure. The United States government has mandated that federal agencies must complete the transition to an IPv6 infrastructure no later than 2008. Software companies are also releasing operating systems that support the IPv6 standard. In 1997, IBM became the first commercial vendor to support IPv6 through its AIX 4.3 operating system. The latest version of Microsoft's Windows operating system, Windows Vista, has full IPv6 support enabled by default.