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Packet switching is a communications paradigm in which packets (discrete blocks of data) are routed between nodes over data links shared with other traffic. In each network node, packets are queued or buffered, resulting in variable delay. This contrasts with the other principal paradigm, circuit switching, which sets up a limited number of constant bit rate and constant delay connections between nodes for their exclusive use for the duration of the communication. Image File history File links Broom_icon. ... For other uses, see Paradigm (disambiguation). ... In information technology, a packet is a formatted block of data carried by a packet mode computer network. ... This article is about routing (or routeing) in computer networks. ... Node(Latin nodus ‘knot’) is critical element of any computer network. ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ...

Packet mode or packet oriented communication may be utilized with or without a packet switch, in the latter case directly between two hosts. Examples of that are point-to-point data links, digital video and audio broadcasting or a shared physical medium, such as a bus network, ring network, or hub network.

Packet mode communication is a statistical multiplexing technique, also known as a dynamic bandwidth allocation method, where a physical communication channel is effectively divided into an arbitrary number of logical variable bit-rate channels or data streams. Each logical stream consists of a sequence of packets, which normally are forwarded by a network node asynchronously in a first-come first-serve fashion. Alternatively, the packets may be forwarded according to some scheduling discipline for fair queuing or differentiated and/or guaranteed Quality of service. In case of a shared physical media, the packets may be delivered according to some packet-mode multiple access scheme. Statistical multiplexing is similar to time-division multiplexing (TDM), except that, rather than arbitrarily assigning a time slot to each signal, each signal is assigned a slot according to priority and need. ... Fair Queuing (FQ), is a scheduling scheme used in computer networks and statistical multiplexing to allow several data flows to fairly share the link capacity. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service, abbreviated QoS, refers to resource reservation control mechanisms. ... In telecommunication, the term multiple access has the following meanings: The connection of a user to two or more switching centers by separate access lines using a single message routing indicator or telephone number. ...

The service actually provided to the user by networks using packet switching internally to the network can be datagrams (connectionless messages), and/or virtual circuit switching (also known as connection oriented). Some connectionless protocols are Ethernet, IP, and UDP; connection oriented protocols include X.25, Frame relay, Asynchronous Transfer Mode (ATM), Multiprotocol Label Switching (MPLS), and TCP. In a packet-switched network, connectionless mode transmission is transmission in which each packet is prepended with a header containing a destination address sufficient to permit the independent delivery of the packet without the aid of additional instructions. ... A connection-oriented networking protocol is one which identifies traffic flows by some connection identifier rather than by explicitly listing source and destination addresses. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. ... User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... In computer networking and telecommunications, Multi Protocol Label Switching (MPLS) is a data-carrying mechanism that belongs to the family of packet-switched networks. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ...

It's also entirely possible to have to weigh the various metrics against each other. For example, reducing the hop count could increase the latency to an unacceptable limit and some kind of balance would need to be found. For multi-parameter optimization, some form of optimization may be needed. In telecommunications, multiplexing (also muxing or MUXing) is the combining of two or more information channels onto a common transmission medium using hardware called a multiplexer or (MUX). ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ... Time-Division Multiplexing (TDM) is a type of digital or (rarely) analog multiplexing in which two or more signals or bit streams are transferred apparently simultaneously as sub-channels in one communication channel, but physically are taking turns on the channel. ... Frequency-division multiplexing (FDM) is a form of signal multiplexing where multiple baseband signals are modulated on different frequency carrier waves and added together to create a composite signal. ... In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different wavelengths (colours) of laser light to carry different signals. ... In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ... Spatial multiplexing is a transmission technique in MIMO wireless communication to transmit independent and separately encoded data signals, so called streams, from each of the multiple transmit antennas. ... Statistical multiplexing is similar to time-division multiplexing (TDM), except that, rather than arbitrarily assigning a time slot to each signal, each signal is assigned a slot according to priority and need. ... Wikipedia does not yet have an article with this exact name. ... Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. ... Frequency-hopping spread spectrum (FHSS) is a spread-spectrum method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. ... In telecommunications, direct-sequence spread spectrum (DSSS) is a modulation technique. ... Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of the popular OFDM digital modulation scheme. ... In communications, a channel access method is used to share a communications channel or physical communications medium between multiple users. ... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ... In mathematics, the term optimization, or mathematical programming, refers to the study of problems in which one seeks to minimize or maximize a real function by systematically choosing the values of real or integer variables from within an allowed set. ...

Once a route is determined for a packet, it is entirely possible that the route may change for the next packet, thus leading to a case where packets from the same source headed to the same destination could be routed differently.

Packet switching influenced the development of the Actor model of concurrent computation in which messages sent to the same address may be delivered in an order different from the order in which they were sent. In computer science, the Actor model is a mathematical model of concurrent computation that treats actors as the universal primitives of concurrent digital computation: in response to a message that it receives, an actor can make local decisions, create more actors, send more messages, and determine how to respond to...

Packet switching in networks

Main article: Packet switched network

Packet switching is used to optimize the use of the channel capacity available in a network, to minimize the transmission latency (i.e. the time it takes for data to pass across the network), and to increase robustness of communication. // A Packet Switched Network, or PSN, refers to the packet switched networks that existed before Internet. ... This article does not cite any references or sources. ... Latency is a time delay between the moment something is initiated, and the moment one of its effects begins. ... In the context of computer software, robustness is the resilience of the system, especially when under stress or when confronted with invalid input. ...

The most well-known use of packet switching is the Internet and local area networks. The Internet uses the Internet protocol suite over a variety of data link layer protocols. For example, Ethernet and Frame relay are very common. Newer mobile phone technologies (e.g., GPRS, I-mode) also use packet switching. LAN redirects here. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... This article does not cite any references or sources. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... In the context of computer networking, frame relay consists of an efficient data transmission technique used to send digital information quickly and cheaply in a relay of frames to one or many destinations from one or many end-points. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM mobile phones. ... NTT DoCoMos i-mode is a wireless Internet service popular in Japan and is increasing in popularity in other parts of the world, such as the Israel (Cellcom being the main company to sell i-mode phones and service there). ...

X.25 is a notable use of packet switching in that, despite being based on packet switching methods, it provided virtual circuits to the user. These virtual circuits carry variable-length packets. In 1978, X.25 was used to provide the first international and commercial packet switching network, the International Packet Switched Service (IPSS). Asynchronous Transfer Mode (ATM) also is a virtual circuit technology, which uses fixed-length cell relay connection oriented packet switching. X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... In telecommunications and computer networks, a virtual circuit (VC), synonymous to virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication. ... Year 1978 (MCMLXXVIII) was a common year starting on Sunday (link displays the 1978 Gregorian calendar). ... X.25 is an ITU-T standard protocol suite for wide area networks using leased lines, the phone or ISDN system as the networking hardware. ... The International Packet Switched Service (IPSS) was created in 1978 by a collaboration between the UKs General Post Office, Western Union International, and Tymnet. ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... In telecommunications, cell relay refers to a method of statistically multiplexing fixed-length packets, i. ...

Datagram packet switching is also called connectionless networking because no connections are established. Technologies such as Multiprotocol Label Switching (MPLS) and the Resource Reservation Protocol (RSVP) create virtual circuits on top of datagram networks. Virtual circuits are especially useful in building robust failover mechanisms and allocating bandwidth for delay-sensitive applications. In computer networking and telecommunications, Multi Protocol Label Switching (MPLS) is a data-carrying mechanism that belongs to the family of packet-switched networks. ... The Resource ReSerVation Protocol (RSVP), described in RFC 2205, is a Transport layer protocol designed to reserve resources across a network for an integrated services Internet. ...

MPLS and its predecessors, as well as ATM, have been called "fast packet" technologies. MPLS, indeed, has been called "ATM without cells" ^[1]. Modern routers, however, do not require these technologies to be able to forward variable-length packets at multigigabit speeds accross the network. This article is about a computer networking device. ...

History of packet switching

The concept of packet switching was first explored by Paul Baran in the early 1960's, and then independently a few years later by Donald Davies (Abbate, 2000). Paul Baran (born 1926) was one of the developers of packet-switched networks along with Donald Davies and Leonard Kleinrock. ... Donald Davies Donald Watts Davies CBE FRS (June 7, 1924 – May 28, 2000) was a British computer scientist who was a co-inventor of packet switching (and originator of the term), along with Paul Baran and Leonard Kleinrock in the US. Just prior to Davies death, he contested Kleinrocks...

Leonard Kleinrock conducted early research in queueing theory which would be important in packet switching, and published a book in the related field of digital message switching (without the packets) in 1961; he also later played a leading role in building and management of the world's first packet switched network, the ARPANET. Leonard Kleinrock and the first IMP. source: (http://www. ... Queueing theory (also commonly spelled queuing theory) is the mathematical study of waiting lines (or queues). ... In telecommunications, message switching was the precursor of packet switching, where messages were routed in their entirety, one hop at a time. ... ARPANET logical map, March 1977. ...

Baran developed the concept of packet switching during his research at the RAND Corporation for the US Air Force into survivable communications networks, first published as RAND Paper P-2626 in 1962 [1], and then including and expanding somewhat within a series of eleven papers titled On Distributed Communications in 1964 [2]. Baran's P-2626 paper described a general architecture for a large-scale, distributed, survivable communications network. The paper focuses on three key ideas: first, use of a decentralized network with multiple paths between any two points; and second, dividing complete user messages into what he called message blocks (later called packets); then third, delivery of these messages by store and forward switching. Alternate meanings: See RAND (disambiguation) The RAND Corporation is an American think tank first formed to offer research and analysis to the U.S. military. ... Decentralisation (or decentralization) is any of various means of more widely distributing decision-making to bring it closer to the point of service or action. ... Store and forward is a communications technique in which messages are sent to a intermediate station where they are kept and sent at a later time to the final destination or to another intermediate station. ...

Baran's study made its way to Robert Taylor and J.C.R. Licklider at the Information Processing Technology Office, both wide-area network evangelists, and it helped influence Lawrence Roberts to adopt the technology when Taylor put him in charge of development of the ARPANET. Robert Taylor was director of ARPAs Information Processing Techniques Office (1965-69), founder and associate manager of Xerox PARCs Computer Science Laboratory (CSL [[1]]) (1970-77), manager of Xerox PARC CSL (1977-83), founder and manager of Digital Equipment Corporations Systems Research Center (1983-96). ... Joseph Carl Robnett Licklider (March 11, 1915 - June 26, 1990), known simply as J.C.R. or Lick is one of the most important figures in computer science and general computing history. ... The Information Processing Technology Office is an agency of the Defense Advanced Research Projects Agency whose stated mission is: [To] create a new generation of computational and information systems that possess capabilities far beyond those of current systems. ... Lawrence Roberts (born October 20, 1982) is a professional basketball player in the NBA. He was a second round draft pick of the Seattle Sonics in the 2005 NBA Draft and was then traded to the Memphis Grizzlies. ... ARPANET logical map, March 1977. ...

Baran's packet switching work was similar to the research performed independently by Donald Davies at the National Physical Laboratory, UK. In 1965, Davies developed the concept of packet switched networks and proposed development of a UK wide network. He gave a talk on the proposal in 1966, after which a person from the Ministry of Defense told him about Baran's work. Davies met Lawrence Roberts at the 1967 ACM Symposium on Operating System Principles, bringing the two groups together. Donald Davies Donald Watts Davies CBE FRS (June 7, 1924 – May 28, 2000) was a British computer scientist who was a co-inventor of packet switching (and originator of the term), along with Paul Baran and Leonard Kleinrock in the US. Just prior to Davies death, he contested Kleinrocks... The National Physical Laboratory (NPL) is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington in the London Borough of Richmond upon Thames. ... The Association for Computing Machinery, or ACM, was founded in 1947 as the worlds first scientific and educational computing society. ...

Interestingly, Davies had chosen some of the same parameters for his original network design as Baran, such as a packet size of 1024 bits. Roberts and the ARPANET team took the name "packet switching" itself from Davies's work.

See also

• Store and forward delay
• Circuit switching
• Message switching
• Public switched data network
• Packet switched network
• Optical burst switching
• Statistical multiplexing
• ALOHAnet

In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ... In telecommunications, message switching was the precursor of packet switching, where messages were routed in their entirety, one hop at a time. ... PSDN is an acronym for public switched data network, a publicly-available network supporting packet-switched data, separate from the PSTN. In the UK, this term refers only to PSS (Packet Switch Stream), an X.25-based packet-switched network, originally used to provide leased-line Internet connections. ... // A Packet Switched Network, or PSN, refers to the packet switched networks that existed before Internet. ... Optical burst switching OBS is a switching concept which lies between optical circuit switching and optical packet switching. ... Statistical multiplexing is similar to time-division multiplexing (TDM), except that, rather than arbitrarily assigning a time slot to each signal, each signal is assigned a slot according to priority and need. ... ALOHAnet, also known as ALOHA, was a pioneering computer networking system developed at the University of Hawaii. ...

References

• Leonard Kleinrock, Information Flow in Large Communication Nets, (MIT, Cambridge, May 31, 1961) Proposal for a Ph.D. Thesis
• Leonard Kleinrock. Information Flow in Large Communication Nets (RLE Quarterly Progress Report, July 1961)
• Leonard Kleinrock. Communication Nets: Stochastic Message Flow and Delay (Mcgraw-Hill, New York, 1964)
• Paul Baran et al., On Distributed Communications, Volumes I-XI (RAND Corporation Research Documents, August, 1964)
  • Paul Baran, On Distributed Communications: I Introduction to Distributed Communications Network (RAND Memorandum RM-3420-PR. August 1964)
• Paul Baran, On Distributed Communications Networks, (IEEE Transactions on Communications Systems, March 1964)
• D. W. Davies, K. A. Bartlett, R. A. Scantlebury, and P. T. Wilkinson, A digital communications network for computers giving rapid response at remote terminals (ACM Symposium on Operating Systems Principles. October 1967)
• R. A. Scantlebury, P. T. Wilkinson, and K. A. Bartlett, The design of a message switching Centre for a digital communication network (IFIP 1968)
• Larry Roberts and Tom Merrill, Toward a Cooperative Network of Time-Shared Computers (Fall AFIPS Conference. October 1966)
• Lawrence Roberts, The Evolution of Packet Switching (Proceedings of the IEEE, November, 1978)

The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...

Further reading

• Katie Hafner, Where Wizards Stay Up Late (Simon and Schuster, 1996) pp 52-67
• Janet Abbate, Inventing the Internet (MIT Press, 2000) ISBN 0-262-51115-0

External links

• Packet Switching History and Design, site reviewed by Baran, Roberts, and Kleinrock
• Paul Baran and the Origins of the Internet
• A Brief History of the Internet

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL. This article does not cite any references or sources. ... “GFDL” redirects here. ...