IPv6

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. IPv6 is intended to replace IPv4.

Every device on the Internet is assigned an IP address for identification and location definition. With the rapid growth of the Internet after commercialization in the 1990s, it became evident that far more addresses than the IPv4 address space has available were necessary to connect new devices in the future. By 1998, the Internet Engineering Task Force (IETF) had formalized the successor protocol. IPv6 uses a 128-bit address, theoretically allowing 2¹²⁸, or approximately 7038340000000000000♠3.4×10³⁸ addresses. The actual number is slightly smaller, as multiple ranges are reserved for special use or completely excluded from use. The total number of possible IPv6 address is more than 7028790000000000000♠7.9×10²⁸ times as many as IPv4, which uses 32-bit addresses and provides approximately 4.3 billion addresses. The two protocols are not designed to be interoperable, complicating the transition to IPv6. However, several IPv6 transition mechanisms have been devised to permit communication between IPv4 and IPv6 hosts.

Internet Stream Protocol

The Internet Stream Protocol (ST and later ST-II) is a family of experimental protocols first defined in Internet Experiment Note IEN-119 (1979), and later substantially revised in RFC 1190 (ST-II) and RFC 1819 (ST2+).

The Internet Stream Protocol family was never introduced for public use, but many of the concepts available in ST are similar to later Asynchronous Transfer Mode protocols and can be found in Multiprotocol Label Switching (MPLS). They also presaged Voice over IP.

ST arose as the transport protocol of the Network Voice Protocol, a pioneering computer network protocol for transporting human speech over packetized communications networks, first implemented in December 1973 by Internet researcher Danny Cohen of the Information Sciences Institute (ISI) as part of ARPA's Network Secure Communications (NSC) project.

First specified in 1979, ST was envisioned to be a connection-oriented complement to IPv4, operating on the same level as IP but using a different header format from that used for IP datagrams. According to IEN-119, its concepts came from Danny Cohen, Estil Hoversten, and James W. Forgie. The protocol was notable for introducing the concepts of packetized voice (now Voice over IP), a talkspurt (a continuous segment of speech between silent intervals), and specified delay and drop-rate requirements for packet services. It was implemented in the Voice Funnel.

Internet Protocol

The Internet Protocol (IP) is the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.

IP has the task of delivering packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this purpose, IP defines packet structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram with source and destination information.

Historically, IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974; the other being the connection-oriented Transmission Control Protocol (TCP). The Internet protocol suite is therefore often referred to as TCP/IP.

The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the Internet. Its successor is Internet Protocol Version 6 (IPv6).