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X.25 Protocol Suite
X.25 is an ITU-T standard protocol suite for packet-switched data communication in wide area networks (WAN). It was originally defined by the International Telegraph and Telephone Consultative Committee (CCITT, now ITU-T) in a series of drafts and finalized in a publication known as ''The Orange Book'' in 1976.CCITT, Study Group VII, ''Draft Recommendation X-25'', March 1976 The protocol suite is designed as three conceptual layers, which correspond closely to the lower three layers of the seven-layer OSI Reference Model, although it was developed several years before the OSI model (1984). It also supports functionality not found in the OSI network layer. An X.25 WAN consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, plain old telephone service connections, or ISDN connections as physical links. X.25 was popular with telecommunications companies for their public data networks from the late 1970s to 1990s, which provided worldwide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T
The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating Standardization, standards for telecommunications and Information Communication Technology, such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, convenes every four years. ITU-T has a permanent Secretariat (administrative office), secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Seizo Onoe (of Japan), whose 4-year term commenced on 1 January 2023. Seizo Onoe succeeded Chaesub Lee of South Korea, who was director from 1 J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CYCLADES
The CYCLADES computer network () was a French research network created in the early 1970s. It was one of the pioneering networks experimenting with the concept of packet switching and, unlike the ARPANET, was explicitly designed to facilitate internetworking. The CYCLADES network was the first to make the hosts responsible for the reliable delivery of data, rather than this being a centralized service of the network itself. Datagrams were exchanged on the network using transport protocols that do not guarantee reliable delivery, but only attempt best-effort. To empower the network leaves the hosts to perform error-correction, the network ensured end-to-end protocol transparency, a concept later to be known as the end-to-end principle. This simplified network design, reduced network latency, and reduced the opportunities for single point failures. The experience with these concepts led to the design of key features of the Internet Protocol in the ARPANET project. The network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postes, Télégraphes Et Téléphones
Postes, Télégraphes et Téléphones (), also known as P&T, P et T and PTT, was the French administration of postal services and telecommunications, founded in 1879 during the Third Republic. The French PTT pioneered the virtual circuit variant of packet switching in the early 1970s through the work of Rémi Després. The company rolled out Minitel'','' a Videotex online service accessible through telephone lines, experimentally between July 1980 in Saint-Malo, France, and from autumn 1980 in other areas, and introduced it commercially throughout France in 1982. Minitel was the world's most successful online service prior to the World Wide Web. The name ''Postes, Télécommunication et Télédiffusion'' never received official recognition from the French state. It was above all used in French campaigns, in unofficial texts and in film credits. In effect, Télédiffusion, which grouped together television and radio channels, was always independent. It was divided in 1991 int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Post Office Telecommunications
BT Group plc (formerly British Telecom) is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, broadband and mobile services in the UK, and also provides subscription television and IT services. BT's origins date back to the founding in 1846 of the Electric Telegraph Company, the world's first public telegraph company, which developed a nationwide communications network. BT Group as it came to be started in 1912, when the General Post Office, a government department, took over the system of the National Telephone Company becoming the monopoly telecoms supplier in the United Kingdom. The Post Office Act of 1969 led to the GPO becoming a public corporation, Post Office Telecommunications. The ''British Telecom'' brand was introduced in 1980, and became independent of the Post Office in 1981, officially trading under the name. British Telecom was privat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Switch Stream
Packet Switch Stream (PSS) was a public data network in the United Kingdom, provided by British Telecommunications (BT). It operated from the late 1970s through to the mid-2000s. Research, development and implementation EPSS Roger Scantlebury was seconded from the National Physical Laboratory to the British Post Office Telecommunications division (BPO-T) in 1969. He had worked with Donald Davies in the late 1960s pioneering the implementation of packet switching and the associated communication protocols on the local-area NPL network. By 1973, BPO-T engineers had developed a packet-switching communication protocol from basic principles for an Experimental Packet Switched Service (EPSS) based on a virtual call capability. However, the protocols were complex and limited; Donald Davies described them as "esoteric". Ferranti supplied the hardware and software. The handling of link control messages (acknowledgements and flow control) was different from that of most other network ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Packet Switching
In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consist of a header (computing), header and a payload (computing), payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or Protocol stack, higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide. During the early 1960s, American engineer Paul Baran developed a concept he called ''distributed adaptive message block switching'', with the goal of providing a fault-tolerant, efficient routing method for telecommunication messages as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His ideas contradicted t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Research Projects Agency
The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Advanced Research Projects Agency (ARPA), the agency was created on February 7, 1958, by President Dwight D. Eisenhower in response to the Soviet launching of Sputnik 1 in 1957. By collaborating with academia, industry, and government partners, DARPA formulates and executes research and development projects to expand the frontiers of technology and science, often beyond immediate U.S. military requirements.Dwight D. Eisenhower and Science & Technology, (2008). Dwight D. Eisenhower Memorial CommissionSource The name of the organization first changed from its founding name, ARPA, to DARPA, in March 1972, changing back to ARPA in February 1993, then reverted to DARPA in March 1996. ''The Economist'' has called DARPA "the agency that shaped the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARPANET
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first computer networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the Advanced Research Projects Agency (now DARPA) of the United States Department of Defense. Building on the ideas of J. C. R. Licklider, Robert Taylor (computer scientist), Bob Taylor initiated the ARPANET project in 1966 to enable resource sharing between remote computers. Taylor appointed Lawrence Roberts (scientist), Larry Roberts as program manager. Roberts made the key decisions about the request for proposal to build the network. He incorporated Donald Davies' concepts and designs for packet switching, and sought input from Paul Baran on dynamic routing. In 1969, ARPA awarded the contract to build the Interface Message Processors (IMPs) for the network to Bolt Berane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halvor Bothner-By
Halvor Bothner-By (August 20, 1938 - June 13, 2014) was a telecommunication engineer of the Norwegian Telecommunications Administration. He was a rapporteur on packet switching for the CCITT. As such, he chaired the group that, in March 1975, proposed to the CCITT Recommendation X.2x on virtual circuits to be offered by public networks. After its unanimous approval at the May 1976 CCITT plenary, it became the well-known protocol X.25. He was also renowned for having coined the term ''datagram A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The de ...'' in the early seventies on a train between Paris and Rennes on the way to attend a CEPT Rapporteur meeting. X.25 Virtual Circuits — Transpac in France — Pré-Internet Data Networking References 1938 births 2014 deaths Telecomm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lawrence Roberts (scientist)
Larry Roberts (December 21, 1937 – December 26, 2018) was an American computer scientist and Internet pioneer. As a program manager and later office director at the Advanced Research Projects Agency, Roberts and his team created the ARPANET, the first wide-area computer network to implement packet switching techniques invented by British computer scientist Donald Davies and American engineer Paul Baran. The ARPANET's principal designer was Bob Kahn, alongside several other computer scientists from Bolt Beranek and Newman (BBN) who worked on the Interface Message Processors (IMPs) and their communication protocols. Roberts asked Leonard Kleinrock to apply mathematical methods to model and measure the performance of the network. In the 1970s, ARPA sponsored research on communication protocols for internetworking, using concepts pioneered by Louis Pouzin, that led to the development of the modern Internet. After his work at ARPA, Roberts became CEO of the commercial packet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Circuit
A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is first established across the network between two endpoints. The network, rather than having a fixed data rate reservation per connection as in circuit switching, takes advantage of the statistical multiplexing on its transmission links, an intrinsic feature of packet switching. A 1978 standardization of virtual circuits by the CCITT imposes per-connection Flow control (data), flow controls at all user-to-network and network-to-network interfaces. This permits participation in congestion control and reduces the likelihood of packet loss in a heavily loaded network. Some circuit protocols provide Reliability (computer networking), reliable communication service through the use of data retransmissions invoked by error detection and automatic repeat request (ARQ). Before a virtual circuit may be used, it must be established between network nodes in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
