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Internet Backbone
The Internet backbone may be defined by the principal data routes between large, strategically interconnected computer networks and core routers of the Internet. These data routes are hosted by commercial, government, academic and other high-capacity network centers, as well as the Internet exchange points and network access points, that exchange Internet traffic between the countries, continents, and across the oceans. Internet service providers, often Tier 1 networks, participate in Internet backbone traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering. The Internet, and consequently its backbone networks, do not rely on central control or coordinating facilities, nor do they implement any global network policies. The resilience of the Internet results from its principal architectural features, most notably the idea of placing as few network state and control functions as possible in the network elements a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Map 1024
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing. The origins of the Internet date back to the development of packet switching and research commissioned by the United States Department of Defense in the 1960s to enable time-sharing of computers. The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1970s to enable resource sharing. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Fiber
An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer. Fibers are also used for illumination and imaging, and are often wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MCI Communications
MCI Communications Corp. (originally Microwave Communications, Inc.) was a telecommunications company headquartered in Washington, D.C. that was at one point the second-largest long-distance provider in the United States. MCI was instrumental in legal and regulatory changes that led to the breakup of the Bell System and introduced competition in the telephone industry. Its MCI Mail, launched in 1983, was one of the first Email services and its MCI.net was an integral part of the Internet backbone. The company was acquired by WorldCom (later called MCI Inc.) in 1998. History Founding MCI was founded as Microwave Communications, Inc. on October 3, 1963, with John D. Goeken being named the company's first president. The initial business plan was for the company to build a series of microwave radio relay stations between Chicago, Illinois, and St. Louis, Missouri. The relay stations would then be used to interface with limited-range two-way radios used by truckers along U.S. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-carrier
The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell System, and could transmit up to 24 telephone calls simultaneously over a single transmission line of copper wire. Subsequent specifications carried multiples of the basic T1 (1.544 Mbit/s) data rates, such as T2 (6.312 Mbit/s) with 96 channels, T3 (44.736 Mbit/s) with 672 channels, and others. Although a ''T2'' was defined as part of AT&T's T-carrier system, which defined five levels, T1 through T5, only the T1 and T3 were commonly in use.1999 ad: On the left, in an aisle seat, a man who very much "filled" his airline seat while on the right side of the aisle is a height-challenged man whose shoe toes barely reach the floor Transmission System 1 The T-carrier is a hardware specification for carrying multiple time-division mul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Science Foundation Network
The National Science Foundation Network (NSFNET) was a program of coordinated, evolving projects sponsored by the National Science Foundation (NSF) from 1985 to 1995 to promote advanced research and education networking in the United States. The program created several nationwide backbone computer networks in support of these initiatives. Initially created to link researchers to the NSF-funded supercomputing centers, through further public funding and private industry partnerships it developed into a major part of the Internet backbone. The National Science Foundation permitted only government agencies and universities to use the network until 1989 when the first commercial Internet service provider emerged. By 1991, the NSF removed access restrictions and the commercial ISP business grew rapidly. History Following the deployment of the Computer Science Network (CSNET), a network that provided Internet services to academic computer science departments, in 1981, the U.S. National ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interface Message Processor
The Interface Message Processor (IMP) was the packet switching node used to interconnect participant networks to the ARPANET from the late 1960s to 1989. It was the first generation of gateways, which are known today as routers. An IMP was a ruggedized Honeywell DDP-516 minicomputer with special-purpose interfaces and software. In later years the IMPs were made from the non-ruggedized Honeywell 316 which could handle two-thirds of the communication traffic at approximately one-half the cost. An IMP requires the connection to a host computer via a special bit- serial interface, defined in ''BBN Report 1822''. The IMP software and the ARPA network communications protocol running on the IMPs was discussed in , the first of a series of standardization documents published by what later became the Internet Engineering Task Force (IETF). History The concept of an "Interface computer" was first proposed in 1966 by Donald Davies for the NPL network in England. The same idea was inde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University College London
, mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = £1.544 billion (2019/20) , chancellor = Anne, Princess Royal(as Chancellor of the University of London) , provost = Michael Spence , head_label = Chair of the council , head = Victor L. L. Chu , free_label = Visitor , free = Sir Geoffrey Vos , academic_staff = 9,100 (2020/21) , administrative_staff = 5,855 (2020/21) , students = () , undergrad = () , postgrad = () , coordinates = , campus = Urban , city = London, England , affiliations = , colours = Purple and blue celeste , nickname ... [...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 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 (ARPA) of the United States Department of Defense. Building on the ideas of J. C. R. Licklider, Bob Taylor initiated the ARPANET project in 1966 to enable access to remote computers. Taylor appointed Larry Roberts as program manager. Roberts made the key decisions about the network design. He incorporated Donald Davies' concepts and designs for packet switching, and sought input from Paul Baran. ARPA awarded the contract to build the network to Bolt Beranek & Newman who developed the first protocol for the network. Roberts engaged Leonard Kleinrock at UCLA to develop mathematical methods for analyzing the packet network technology. The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NPL Network
The NPL network, or NPL Data Communications Network, was a local area computer network operated by a team from the National Physical Laboratory in London that pioneered the concept of packet switching. Based on designs first conceived by Donald Davies in 1965, development work began in 1968. Elements of the first version of the network, the Mark I, became operational during 1969 then fully operational in January 1970, and the Mark II version operated from 1973 until 1986. The NPL network and the ARPANET in the United States were the first two computer networks that implemented packet switching and the NPL network was the first to use high-speed links. Origins In 1965, Donald Davies, who was later appointed to head of the NPL Division of Computer Science, proposed a commercial national data network based on packet switching in ''Proposal for the Development of a National Communications Service for On-line Data Processing''. After the proposal was not taken up nationally, during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Signaling Rate
In telecommunication, data signaling rate (DSR), also known as gross bit rate, is the aggregate rate at which data passes a point in the transmission path of a data transmission system. # The DSR is usually expressed in bits per second. # The data signaling rate is given by \sum_^ \frac where ''m'' is the number of parallel channels, ''ni'' is the number of significant conditions of the modulation in the ''i''-th channel, and ''Ti'' is the unit interval, expressed in seconds, for the ''i''-th channel. # For serial transmission in a single channel, the DSR reduces to (1/''T'')log2''n''; with a two-condition modulation, i. e. ''n'' = 2, the DSR is 1/''T'', according to Hartley's law. # For parallel transmission with equal unit intervals and equal numbers of significant conditions on each channel, the DSR is (''m''/''T'')log2''n''; in the case of a two-condition modulation, this reduces to ''m''/''T''. # The DSR may be expressed in bauds, in which case, the factor log2''ni'' in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repeater
In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some types of repeaters broadcast an identical signal, but alter its method of transmission, for example, on another frequency or baud rate. There are several different types of repeaters; a telephone repeater is an amplifier in a telephone line, an optical repeater is an optoelectronic circuit that amplifies the light beam in an optical fiber cable; and a radio repeater is a radio receiver and transmitter that retransmits a radio signal. A broadcast relay station is a repeater used in broadcast radio and television. Overview When an information-bearing signal passes through a communication channel, it is progressively degraded due to loss of power. For example, when a telephone call passes through a wire telephone line, some of the powe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
