Introduction to IPv6

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Introduction to IPv6

The current version of the Internet Protocol (known as IP version 4 or IPv4) has not been substantially changed since RFC 791 was published in 1981. IPv4 has proven to be robust, easily implemented and interoperable, and has stood the test of scaling an internetwork to a global utility the size of today's Internet. This is a tribute to its initial design.

However, the initial design did not anticipate:

  • The recent exponential growth of the Internet and the impending exhaustion of the IPv4 address space.

    IPv4 addresses have become relatively scarce, forcing some organizations to use a network address translator (NAT) to map multiple private addresses to a single public IP address. While NATs promote reuse of the private address space, they do not support standards-based network layer security or the correct mapping of all higher layer protocols and can create problems when connecting two organizations that use the private address space.

    Additionally, the rising prominence of Internet-connected devices and appliances assures that the public IPv4 address space will eventually be depleted.

  • The growth of the Internet and the ability of Internet backbone routers to maintain large routing tables.

    Because of the way in which IPv4 network IDs have been and are currently allocated, there are routinely over 70,000 routes in the routing tables of Internet backbone routers. The current IPv4 Internet routing infrastructure is a combination of both flat and hierarchical routing.

  • The need for simpler configuration.

    Most current IPv4 implementations must be configured either manually or through a stateful address configuration protocol such as Dynamic Host Configuration Protocol (DHCP). With more computers and devices using IP, there is a need for a simpler and more automatic configuration of addresses and other configuration settings that do not rely on the administration of a DHCP infrastructure.

  • The requirement for security at the IP level.

    Private communication over a public medium like the Internet requires encryption services that protect the data sent from being viewed or modified in transit. Although a standard now exists for providing security for IPv4 packets (known as Internet Protocol security or IPSec), this standard is optional and proprietary solutions are prevalent.

  • The need for better support for real-time delivery of data (also known as quality of service).

    While standards for quality of service (QoS) exist for IPv4, real-time traffic support relies on the IPv4 Type of Service (TOS) field and the identification of the payload, typically using a UDP or TCP port. Unfortunately, the IPv4 TOS field has limited functionality and has different interpretations. In addition, payload identification using a TCP and UDP port is not possible when the IPv4 packet payload is encrypted.

To address these concerns, the Internet Engineering Task Force (IETF) has developed a suite of protocols and standards known as IP version 6 (IPv6). This new version, previously named IP-The Next Generation (IPng), incorporates the concepts of many proposed methods for updating the IPv4 protocol. IPv6 is intentionally designed for minimal impact on upper and lower layer protocols by avoiding the arbitrary addition of new features.