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telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...
s, packet switching is a method of grouping
data In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted ...
into '' packets'' that are transmitted over a digital
network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...
. Packets are made of a header and a
payload Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...
. 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 An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
,
application software Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...
, or higher layer protocols. Packet switching is the primary basis for data communications in
computer networks A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ma ...
worldwide. In the early 1960s, American computer scientist
Paul Baran Paul Baran (born Pesach Baran ; April 29, 1926 – March 26, 2011) was a Polish-American engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dom ...
developed the concept that he called "distributed adaptive message block switching", with the goal of providing a
fault-tolerant Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the ...
, efficient routing method for telecommunication messages as part of a research program at the
RAND Corporation The RAND Corporation (from the phrase "research and development") is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed ...
, funded by the
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national secu ...
. His ideas contradicted then-established principles of pre-
allocation Allocation may refer to: Computing * Block allocation map * C++ allocators * Delayed allocation * File allocation table * IP address allocation * Memory allocation * No-write allocation (cache) * Register allocation Economics * Asset alloca ...
of network
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
, exemplified by the development of telecommunications in the
Bell System The Bell System was a system of telecommunication companies, led by the Bell Telephone Company and later by the American Telephone and Telegraph Company (AT&T), that dominated the telephone services industry in North America for over one hundr ...
. The new concept found little resonance among network implementers until the independent work of British computer scientist
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he conceived of packet switching, which is today the dominant basis for data communic ...
at the National Physical Laboratory in 1965. Davies is credited with coining the modern term ''packet switching'' and inspiring numerous packet switching networks in the decade following, including the incorporation of the concept into the design of the
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 fou ...
in the United States. The ARPANET was the primary precursor network of the modern
Internet 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, pub ...
.


Concept

A simple definition of packet switching is: Packet switching allows delivery of
variable bit rate Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a ...
data streams, realized as sequences of packets, over a
computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
which allocates transmission resources as needed using
statistical multiplexing Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...
or
dynamic bandwidth allocation Dynamic bandwidth allocation is a technique by which traffic bandwidth in a shared telecommunications medium can be allocated on demand and fairly between different users of that bandwidth. This is a form of bandwidth management, and is essentiall ...
techniques. As they traverse
networking hardware Networking hardware, also known as network equipment or computer networking devices, are electronic devices which are required for communication and interaction between devices on a computer network. Specifically, they mediate data transmission in ...
, such as switches and routers, packets are received, buffered, queued, and retransmitted ( stored and forwarded), resulting in variable latency and
throughput Network throughput (or just throughput, when in context) refers to the rate of message delivery over a communication channel, such as Ethernet or packet radio, in a communication network. The data that these messages contain may be delivered ov ...
depending on the link capacity and the traffic load on the network. Packets are normally forwarded by intermediate network nodes asynchronously using
first-in, first-out Representation of a FIFO queue In computing and in systems theory, FIFO is an acronym for first in, first out (the first in is the first out), a method for organizing the manipulation of a data structure (often, specifically a data buffer) where ...
buffering, but may be forwarded according to some scheduling discipline for fair queuing,
traffic shaping Traffic shaping is a bandwidth management technique used on computer networks which delays some or all datagrams to bring them into compliance with a desired ''traffic profile''. Traffic shaping is used to optimize or guarantee performance, improv ...
, or for differentiated or guaranteed
quality of service Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...
, such as
weighted fair queuing Weighted fair queueing (WFQ) is a network scheduling algorithm. WFQ is both a packet-based implementation of the generalized processor sharing (GPS) policy, and a natural extension of fair queuing (FQ). Whereas FQ shares the link's capacity in ...
or
leaky bucket The leaky bucket is an algorithm based on an analogy of how a bucket with a constant leak will overflow if either the average rate at which water is poured in exceeds the rate at which the bucket leaks or if more water than the capacity of the ...
. Packet-based communication may be implemented with or without intermediate forwarding nodes (switches and routers). In case of a shared physical medium (such as radio or
10BASE5 10BASE5 (also known as thick Ethernet or thicknet) was the first commercially available variant of Ethernet. The technology was standardized in 1982 as IEEE 802.3. 10BASE5 uses a thick and stiff coaxial cable up to in length. Up to 100 stati ...
), the packets may be delivered according to a
multiple access In telecommunications and computer networks, a channel access method or multiple access method allows more than two terminals connected to the same transmission medium to transmit over it and to share its capacity. Examples of shared physical med ...
scheme. Packet switching contrasts with another principal networking paradigm,
circuit switching Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel ( circuit) through the network before the nodes may communicate. The circuit guarantees the full b ...
, a method which pre-allocates dedicated network bandwidth specifically for each communication session, each having a constant bit rate and latency between nodes. In cases of billable services, such as
cellular communication A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
services, circuit switching is characterized by a fee per unit of connection time, even when no data is transferred, while packet switching may be characterized by a fee per unit of information transmitted, such as characters, packets, or messages. A packet switch has four components: input ports, output ports, routing processor, and switching fabric.


History


Invention and development

The concept of switching small blocks of data was first explored independently by
Paul Baran Paul Baran (born Pesach Baran ; April 29, 1926 – March 26, 2011) was a Polish-American engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dom ...
at the
RAND Corporation The RAND Corporation (from the phrase "research and development") is an American nonprofit global policy think tank created in 1948 by Douglas Aircraft Company to offer research and analysis to the United States Armed Forces. It is financed ...
in the early 1960s in the US and
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he conceived of packet switching, which is today the dominant basis for data communic ...
at the National Physical Laboratory (NPL) in the UK in 1965.; In the late 1950s, the
US Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
established a
wide area network A wide area network (WAN) is a telecommunications network that extends over a large geographic area. Wide area networks are often established with leased telecommunication circuits. Businesses, as well as schools and government entities, us ...
for the
Semi-Automatic Ground Environment The Semi-Automatic Ground Environment (SAGE) was a system of mainframe computer, large computers and associated computer network, networking equipment that coordinated data from many radar sites and processed it to produce a single unified image ...
(SAGE) radar defense system. Recognizing vulnerabilities in this network, the Air Force sought a system that might survive a nuclear attack to enable a response, thus diminishing the attractiveness of the first strike advantage by enemies (see
Mutual assured destruction Mutual assured destruction (MAD) is a doctrine of military strategy and national security policy which posits that a full-scale use of nuclear weapons by an attacker on a nuclear-armed defender with second-strike capabilities would cause the ...
). Baran developed the concept of ''distributed adaptive message block switching'' in support of the Air Force initiative. The concept was first presented to the Air Force in the summer of 1961 as briefing B-265, later published as RAND report P-2626 in 1962, and finally in report RM 3420 in 1964. Report P-2626 described a general architecture for a large-scale, distributed, survivable communications network. The work focuses on three key ideas: use of a
decentralized Decentralization or decentralisation is the process by which the activities of an organization, particularly those regarding planning and decision making, are distributed or delegated away from a central, authoritative location or group. Conce ...
network with multiple paths between any two points, dividing user messages into ''message blocks'', and delivery of these messages by
store and forward Store and forward is a telecommunications technique in which information is sent to an intermediate station where it is kept and sent at a later time to the final destination or to another intermediate station. The intermediate station, or node in ...
switching. Davies independently developed a similar message routing concept and more detailed network design in 1965. He coined the term ''packet switching'', and proposed building a commercial nationwide data network in the UK. He gave a talk on the proposal in 1966, after which a person from the
Ministry of Defence {{unsourced, date=February 2021 A ministry of defence or defense (see spelling differences), also known as a department of defence or defense, is an often-used name for the part of a government responsible for matters of defence, found in states ...
(MoD) told him about Baran's work.
Roger Scantlebury Roger Anthony Scantlebury (born August 1936) is a British computer scientist who worked at the National Physical Laboratory (NPL) and later at Logica. Scantlebury participated in pioneering work to develop packet switching and associated communi ...
, a member of Davies' team met Lawrence Roberts at the 1967
Symposium on Operating Systems Principles In ancient Greece, the symposium ( grc-gre, συμπόσιον ''symposion'' or ''symposio'', from συμπίνειν ''sympinein'', "to drink together") was a part of a banquet that took place after the meal, when drinking for pleasure was acc ...
and suggested it for use in the ARPANET. Davies had chosen some of the same parameters for his original network design as did Baran, such as a packet size of 1024 bits. In 1966, Davies proposed that a network should be built at the laboratory to serve the needs of NPL and prove the feasibility of packet switching. To deal with packet permutations (due to dynamically updated route preferences) and to datagram losses (unavoidable when fast sources send to a slow destinations), he assumed that "all users of the network will provide themselves with some kind of error control", thus inventing what came to be known the
end-to-end principle The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
. After a
pilot experiment A pilot study, pilot project, pilot test, or pilot experiment is a small-scale preliminary study conducted to evaluate feasibility, duration, cost, adverse events, and improve upon the study design prior to performance of a full-scale research pro ...
in 1969, the
NPL Data Communications 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 Donal ...
entered service in 1970.
Leonard Kleinrock Leonard Kleinrock (born June 13, 1934) is an American computer scientist and a long-tenured professor at UCLA's Henry Samueli School of Engineering and Applied Science. In the early 1960s, Kleinrock pioneered the application of queueing theory ...
conducted research into
queueing theory Queueing theory is the mathematical study of waiting lines, or queues. A queueing model is constructed so that queue lengths and waiting time can be predicted. Queueing theory is generally considered a branch of operations research because the ...
for his doctoral dissertation at
MIT The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
in 1961-2 and published it as a book in 1964 in the field of
message switching In telecommunications, message switching involves messages routed in their entirety, one hop at a time. It evolved from circuit switching and was the precursor of packet switching. History Western Union operated a message switching system, Plan ...
. In 1968, Lawrence Roberts contracted with Kleinrock to carry out theoretical work at
UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...
to measure and model the performance of the ARPANET, which underpinned the development of the network in the early 1970s. The NPL team also carried out simulation work on packet networks, including
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 del ...
networks. The French
CYCLADES The Cyclades (; el, Κυκλάδες, ) are an island group in the Aegean Sea, southeast of mainland Greece and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The nam ...
network was designed by
Louis Pouzin Louis Pouzin (April 20, 1931 in Chantenay-Saint-Imbert, Nièvre, France) is a French computer scientist. He designed an early packet communications network, CYCLADES. This network was the first actual implementation of the pure datagram model, ...
in the early 1970s to study
internetworking Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interco ...
. It was the first to implement the
end-to-end principle The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
of Davies, and make the
hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ( ...
responsible for the reliable delivery of data on a packet-switched network, rather than this being a service of the network itself. His team was thus first to tackle the highly complex problem of providing user applications with a reliable
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 established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
service while using a best-effort service, an early contribution to what will be
Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...
(TCP). In May 1974,
Vint Cerf Vinton Gray Cerf (; born June 23, 1943) is an American Internet pioneer and is recognized as one of " the fathers of the Internet", sharing this title with TCP/IP co-developer Bob Kahn. He has received honorary degrees and awards that include t ...
and
Bob Kahn Robert Elliot Kahn (born December 23, 1938) is an American electrical engineer who, along with Vint Cerf, first proposed the Transmission Control Protocol (TCP) and the Internet Protocol (IP), the fundamental communication protocols at the hea ...
described the Transmission Control Program, an internetworking
protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technolog ...
for sharing resources using packet-switching among the nodes. The specifications of the TCP were then published in (''Specification of Internet Transmission Control Program''), written by Vint Cerf,
Yogen Dalal Instead of having a single "inventor", the Internet was developed by many people over many years. The following are some Internet pioneers who contributed to its early and ongoing development. These include early theoretical foundations, specifyi ...
and Carl Sunshine in December 1974. This monolithic protocol was later layered as the
Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...
, ''TCP'', atop the
Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP h ...
, ''IP''. In the late 1970s and early 1980s, national and international
public data network A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public p ...
s emerged based on the
X.25 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 ...
protocol. X.25 is built on the concept of virtual circuits emulating traditional telephone connections. For a period in the late 1980s and early 1990s, the network engineering community was polarized over the implementation of competing protocol suites, commonly known as the
Protocol Wars A long-running debate in computer science known as the Protocol Wars occurred from the 1970s to the 1990s when engineers, organizations and nations became polarized over the issue of which communication protocol would result in the best and most ...
. It was unclear which of the
OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...
and the
Internet protocol suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
would result in the best and most robust computer networks. Complementary
metal–oxide–semiconductor The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...
(
CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFE ...
)
VLSI Very large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining millions or billions of MOS transistors onto a single chip. VLSI began in the 1970s when MOS integrated circuit (Metal Oxide Semiconductor) c ...
(very-
large-scale integration An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...
) technology led to the development of high-speed
broadband In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...
packet switching during the 1980s1990s.


'Paternity' dispute

Beginning in the mid-1990s,
Leonard Kleinrock Leonard Kleinrock (born June 13, 1934) is an American computer scientist and a long-tenured professor at UCLA's Henry Samueli School of Engineering and Applied Science. In the early 1960s, Kleinrock pioneered the application of queueing theory ...
sought to be recognized as the "father of modern data networking". However, Kleinrock's claims that his work in the early 1960s originated the concept of packet switching and that this work was the source of the packet switching concepts used in the ARPANET are disputed by other Internet pioneers, including by Robert Taylor,
Paul Baran Paul Baran (born Pesach Baran ; April 29, 1926 – March 26, 2011) was a Polish-American engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dom ...
, and
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he conceived of packet switching, which is today the dominant basis for data communic ...
. Baran and Davies are recognized by historians and the U.S.
National Inventors Hall of Fame The National Inventors Hall of Fame (NIHF) is an American not-for-profit organization, founded in 1973, which recognizes individual engineers and inventors who hold a U.S. patent of significant technology. Besides the Hall of Fame, it also opera ...
for independently inventing the concept of digital packet switching used in modern computer networking including the Internet.


Connectionless and connection-oriented modes

Packet switching may be classified into
connectionless Connectionless communication, often referred to as CL-mode communication,Information Processing Systems - Open Systems Interconnection, "Transport Service Definition - Addendum 1: Connectionless-mode Transmission", International Organization for ...
packet switching, also known as
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 del ...
switching, and
connection-oriented Connection-oriented communication is a network communication mode in telecommunications and computer networking, where a communication session or a semi-permanent connection is established before any useful data can be transferred. The establish ...
packet switching, also known as
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 established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
switching. Examples of connectionless systems are
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
,
Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP h ...
(IP), and the
User Datagram Protocol In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. ...
(UDP). Connection-oriented systems include
X.25 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 ...
,
Frame Relay Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Se ...
,
Multiprotocol Label Switching Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identif ...
(MPLS), and the
Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...
(TCP). In connectionless mode each packet is labeled with a destination address, source address, and port numbers. It may also be labeled with the sequence number of the packet. This information eliminates the need for a pre-established path to help the packet find its way to its destination, but means that more information is needed in the packet header, which is therefore larger. The packets are routed individually, sometimes taking different paths resulting in
out-of-order delivery In computer networking, out-of-order delivery is the delivery of data packets in a different order from which they were sent. Out-of-order delivery can be caused by packets following multiple paths through a network, by lower-layer retransmissio ...
. At the destination, the original message may be reassembled in the correct order, based on the packet sequence numbers. Thus a
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 established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
carrying a
byte stream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...
is provided to the application by a
transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end ...
protocol, although the network only provides a connectionless
network layer In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers. Functions The network layer provides the means of transfe ...
service. Connection-oriented transmission requires a setup phase to establish the parameters of communication before any packet is transferred. The
signaling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
protocols used for setup allow the application to specify its requirements and discover link parameters. Acceptable values for service parameters may be negotiated. The packets transferred may include a connection identifier rather than address information and the packet header can be smaller, as it only needs to contain this code and any information, such as length, timestamp, or sequence number, which is different for different packets. In this case, address information is only transferred to each node during the connection setup phase, when the route to the destination is discovered and an entry is added to the switching table in each network node through which the connection passes. When a connection identifier is used, routing a packet requires the node to look up the connection identifier in a table. Connection-oriented transport layer protocols such as TCP provide a connection-oriented service by using an underlying connectionless network. In this case, the
end-to-end principle The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
dictates that the end nodes, not the network itself, are responsible for the connection-oriented behavior.


Packet switching in networks

Packet switching is used to optimize the use of the channel capacity available in digital telecommunication networks, such as computer networks, and minimize the transmission latency (the time it takes for data to pass across the network), and to increase
robustness Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
of communication. Packet switching is used in the
Internet 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, pub ...
and most
local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
s. The Internet is implemented by the
Internet Protocol Suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
using a variety of link layer technologies. For example,
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
and
Frame Relay Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Se ...
are common. Newer
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whil ...
technologies (e.g.,
GSM The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...
, LTE) also use packet switching. Packet switching is associated with connectionless networking because, in these systems, no connection agreement needs to be established between communicating parties prior to exchanging data.
X.25 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 ...
is a notable use of packet switching in that, despite being based on packet switching methods, it provides
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 established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
s to the user. These virtual circuits carry variable-length packets. In 1978, X.25 provided the first international and commercial packet switching network, the
International Packet Switched Service The International Packet Switched Service (IPSS) was the first international and commercial packet switching network. It was created in 1978 by a collaboration between Britain's Post Office Telecommunications, and the United States' Western Union In ...
(IPSS).
Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by American National Standards Institute (ANSI) and ITU-T (formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of ...
(ATM) also is a virtual circuit technology, which uses fixed-length
cell relay In computer networking, cell relay refers to a method of statistically multiplexing small fixed-length packets, called "cells", to transport data between computers or kinds of network equipment. It is a reliable, connection-oriented packet swit ...
connection oriented packet switching. Technologies such as
Multiprotocol Label Switching Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identif ...
(MPLS) and the Resource Reservation Protocol (RSVP) create virtual circuits on top of datagram networks. MPLS and its predecessors, as well as ATM, have been called "fast packet" technologies. MPLS, indeed, has been called "ATM without cells". Virtual circuits are especially useful in building robust failover mechanisms and allocating bandwidth for delay-sensitive applications.


Packet-switched networks

The history of packet-switched networks can be divided into three overlapping eras: early networks before the introduction of
X.25 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 ...
; the X.25 era when many postal, telephone, and telegraph (PTT) companies provided
public data network A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public p ...
s with X.25 interfaces; and the
Internet 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, pub ...
era which initially competed with the
OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that 'provides a common basis for the coordination of SOstandards development for the purpose of systems interconnection'. In the OSI reference model, the communications ...
.


Early networks

Research into packet switching at the National Physical Laboratory (NPL) began with a proposal for a wide-area network in 1965, and a local-area network in 1966. ARPANET funding was secured in 1966 by Bob Taylor, and planning began in 1967 when he hired Larry Roberts. The NPL network, ARPANET, and SITA HLN became operational in 1969. Before the introduction of X.25 in 1976, about twenty different network technologies had been developed. Two fundamental differences involved the division of functions and tasks between the hosts at the edge of the network and the network core. In the datagram system, operating according to the
end-to-end principle The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
, the hosts have the responsibility to ensure orderly delivery of packets. In the virtual call system, the network guarantees sequenced delivery of data to the host. This results in a simpler host interface but complicates the network. The X.25 protocol suite uses this network type.


AppleTalk

AppleTalk AppleTalk is a discontinued proprietary suite of networking protocols developed by Apple Computer for their Macintosh computers. AppleTalk includes a number of features that allow local area networks to be connected with no prior setup or the n ...
is a proprietary suite of networking protocols developed by
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
in 1985 for
Apple Macintosh The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software en ...
computers. It was the primary protocol used by Apple devices through the 1980s and 1990s. AppleTalk included features that allowed
local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
s to be established ''ad hoc'' without the requirement for a centralized router or server. The AppleTalk system automatically assigned addresses, updated the distributed namespace, and configured any required inter-network routing. It was a
plug-n-play In computing, a plug and play (PnP) device or computer bus is one with a specification that facilitates the recognition of a hardware component in a system without the need for physical device configuration or user intervention in resolving resou ...
system. AppleTalk implementations were also released for the
IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...
and compatibles, and the
Apple IIGS The Apple IIGS (styled as II), the fifth and most powerful of the Apple II family, is a 16-bit personal computer produced by Apple Computer. While featuring the Macintosh look and feel, and resolution and color similar to the Amiga and Atari ST ...
. AppleTalk support was available in most networked printers, especially
laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to d ...
s, some
file server In computing, a file server (or fileserver) is a computer attached to a network that provides a location for shared disk access, i.e. storage of computer files (such as text, image, sound, video) that can be accessed by the workstations that are ab ...
s and routers. AppleTalk support was terminated in 2009, replaced by
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
protocols.


ARPANET

The
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 fou ...
was a progenitor network of the Internet and one of the first networks, along with ARPA's
SATNET SATNET, also known as the Atlantic Packet Satellite Network, was an early satellite network that formed an initial segment of the Internet. It was implemented by BBN Technologies under the direction of the Advanced Research Projects Agency. T ...
, to run the
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
suite using packet switching technologies.


BNRNET

BNRNET was a network which
Bell-Northern Research Bell-Northern Research (BNR) was a telecommunications research and development company established In 1971 when Bell Canada and Nortel, Northern Electric combined their R&D organizations. It was jointly owned by Bell Canada and Nortel, Northern ...
developed for internal use. It initially had only one host but was designed to support many hosts. BNR later made major contributions to the CCITT
X.25 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 ...
project.


Cambridge Ring

The Cambridge Ring was an experimental
ring network A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node – a ring. Data travels from node to node, with each node along the way handling ever ...
developed at the
Computer Laboratory, University of Cambridge The Department of Computer Science and Technology, formerly the Computer Laboratory, is the computer science department of the University of Cambridge. it employed 35 academic staff, 25 support staff, 35 affiliated research staff, and about 15 ...
. It operated from 1974 until the 1980s.


CompuServe

CompuServe CompuServe (CompuServe Information Service, also known by its initialism CIS) was an American online service provider, the first major commercial one in the world – described in 1994 as "the oldest of the Big Three information services (the oth ...
developed its own packet switching network, implemented on DEC
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
minicomputers acting as network nodes that were installed throughout the US (and later, in other countries) and interconnected. Over time, the CompuServe network evolved into a complicated multi-tiered network incorporating ATM,
Frame Relay Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Se ...
,
Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP h ...
(IP) and
X.25 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 ...
technologies.


CYCLADES

The
CYCLADES The Cyclades (; el, Κυκλάδες, ) are an island group in the Aegean Sea, southeast of mainland Greece and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The nam ...
packet switching network was a French research network designed and directed by
Louis Pouzin Louis Pouzin (April 20, 1931 in Chantenay-Saint-Imbert, Nièvre, France) is a French computer scientist. He designed an early packet communications network, CYCLADES. This network was the first actual implementation of the pure datagram model, ...
. First demonstrated in 1973, it was developed to explore alternatives to the early ARPANET design and to support network research generally. It was the first network to use the
end-to-end principle The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the commu ...
and make the hosts responsible for reliable delivery of data, rather than the network itself. Concepts of this network influenced later ARPANET architecture.


DECnet

DECnet DECnet is a suite of network protocols created by Digital Equipment Corporation. Originally released in 1975 in order to connect two PDP-11 minicomputers, it evolved into one of the first peer-to-peer network architectures, thus transforming DEC ...
is a suite of network protocols created by
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...
, originally released in 1975 in order to connect two
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
minicomputers A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
. It evolved into one of the first
peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a peer-to-peer n ...
network architectures, thus transforming DEC into a networking powerhouse in the 1980s. Initially built with three
layers Layer or layered may refer to: Arts, entertainment, and media * ''Layers'' (Kungs album) * ''Layers'' (Les McCann album) * ''Layers'' (Royce da 5'9" album) *"Layers", the title track of Royce da 5'9"'s sixth studio album *Layer, a female Maveric ...
, it later (1982) evolved into a seven-layer
OSI OSI may refer to: Places * Osijek Airport (IATA code: OSI), an airport in Croatia * Ősi, a village in Veszprém county, Hungary * Oši, an archaeological site in Semigallia, Latvia * Osi, a village in Ido-Osi, Ekiti State, Nigeria * Osi, Ekiti ...
-compliant networking protocol. The DECnet protocols were designed entirely by Digital Equipment Corporation. However, DECnet Phase II (and later) were
open standard An open standard is a standard that is openly accessible and usable by anyone. It is also a prerequisite to use open license, non-discrimination and extensibility. Typically, anybody can participate in the development. There is no single definition ...
s with published specifications, and several implementations were developed outside DEC, including one for
Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
.


DDX-1

DDX-1 was an experimental network from Nippon PTT. It mixed circuit switching and packet switching. It was succeeded by DDX-2.


EIN

The European Informatics Network (EIN), originally called COST 11, was a project beginning in 1971 to link networks in Britain, France, Italy, Switzerland and
Euratom The European Atomic Energy Community (EAEC or Euratom) is an international organisation established by the Euratom Treaty on 25 March 1957 with the original purpose of creating a specialist market for nuclear power in Europe, by developing nucl ...
. Six other European countries also participated in the research on network protocols. Derek Barber directed the project,and
Roger Scantlebury Roger Anthony Scantlebury (born August 1936) is a British computer scientist who worked at the National Physical Laboratory (NPL) and later at Logica. Scantlebury participated in pioneering work to develop packet switching and associated communi ...
led the UK technical contribution; both were from NPL. The contract for its implementation was awarded to an Anglo French consortium led by the UK systems house
Logica Logica plc was a multinational IT and management consultancy company headquartered in London and later Reading, United Kingdom. Founded in 1969, the company had offices in London and in a number of major cities across England, Wales and Scotl ...
and Sesa and managed by
Andrew Karney Andrew Karney, Fellow of the Institution of Engineering and Technology, FIET, Chartered Engineer, CEng, FRSA (born 24 May 1942) is a British electrical engineer, businessman and company director. He is also an accredited European Engineer. Car ...
. Work began in 1973 and it became operational in 1976 including nodes linking the
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 Donal ...
and
CYCLADES The Cyclades (; el, Κυκλάδες, ) are an island group in the Aegean Sea, southeast of mainland Greece and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The nam ...
. The transport protocol of the EIN was the basis of the one adopted by the
International Networking Working Group The International Networking Working Group (INWG) was a group of prominent computer science researchers in the 1970s who studied and developed standards and protocols for computer networking. Set up in 1972 as an informal group to consider the tech ...
. EIN was replaced by Euronet in 1979.


EPSS

The Experimental Packet Switched Service (EPSS) was an experiment of the UK
Post Office Telecommunications Post Office Telecommunications was set up as a separate department of the UK Post Office, in October 1969. The Post Office Act 1969 was passed to provide for greater efficiency in post and telephone services; rather than run a range of services, ...
, based on the
Coloured Book protocols The Coloured Book protocols were a set of communication protocols for computer networks developed in the United Kingdom in the 1970s. The name originated with each protocol being identified by the colour of the cover of its specification document. ...
defined by the UK academic community in 1975. It was the first
public data network A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public p ...
in the UK when it began operating in 1977.
Ferranti Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. The company was once a constituent of the FTSE 100 Index. The firm was known ...
supplied the hardware and software. The handling of link control messages (acknowledgements and flow control) was different from that of most other networks.


GEIS

As General Electric Information Services (GEIS),
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
was a major international provider of information services. The company originally designed a telephone network to serve as its internal (albeit continent-wide) voice telephone network. In 1965, at the instigation of Warner Sinback, a data network based on this voice-phone network was designed to connect GE's four computer sales and service centers (Schenectady, New York, Chicago, and Phoenix) to facilitate a computer time-sharing service. After going international some years later, GEIS created a network data center near
Cleveland Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. ...
, Ohio. Very little has been published about the internal details of their network. The design was hierarchical with redundant communication links.


IPSANET

IPSANET {{No footnotes, date=November 2020 IPSANET was a packet switching network written by I. P. Sharp Associates (IPSA). Operation began in May 1976. It initially used the IBM 3705 Communications Controller and Computer Automation LSI-2 computers as n ...
was a semi-private network constructed by I. P. Sharp Associates to serve their time-sharing customers. It became operational in May 1976.


IPX/SPX

The
Internetwork Packet Exchange Internetwork Packet Exchange (IPX) is the network layer protocol in the IPX/SPX protocol suite. IPX is derived from Xerox Network Systems' IDP. It also has the ability to act as a transport layer protocol. The IPX/SPX protocol suite was very ...
(IPX) and Sequenced Packet Exchange (SPX) are
Novell Novell, Inc. was an American software and services company headquartered in Provo, Utah, that existed from 1980 until 2014. Its most significant product was the multi-platform network operating system known as Novell NetWare. Under the lead ...
networking protocols from the 1980s derived from Xerox Network Systems' IDP and SPP protocols, respectively which date back to the 1970s. IPX/SPX was used primarily on networks using the Novell NetWare operating systems.


Merit Network

Merit Network Merit Network, Inc., is a nonprofit member-governed organization providing high-performance computer networking and related services to educational, government, health care, and nonprofit organizations, primarily in Michigan. Created in 1966, Mer ...
, an independent
nonprofit organization A nonprofit organization (NPO) or non-profit organisation, also known as a non-business entity, not-for-profit organization, or nonprofit institution, is a legal entity organized and operated for a collective, public or social benefit, in co ...
governed by Michigan's public universities,Merit receives administrative services under an agreement with the
University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...
.
was formed in 1966 as the Michigan Educational Research Information Triad to explore computer networking between three of Michigan's public universities as a means to help the state's educational and economic development. With initial support from the
State of Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...
and the
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...
(NSF), the packet-switched network was first demonstrated in December 1971 when an interactive host-to-host connection was made between the
IBM mainframe IBM mainframes are large computer systems produced by IBM since 1952. During the 1960s and 1970s, IBM dominated the large computer market. Current mainframe computers in IBM's line of business computers are developments of the basic design of th ...
systems at the
University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...
in
Ann Arbor Anne, alternatively spelled Ann, is a form of the Latin female given name Anna (name), Anna. This in turn is a representation of the Hebrew Hannah (given name), Hannah, which means 'favour' or 'grace'. Related names include Annie (given name), ...
and
Wayne State University Wayne State University (WSU) is a public research university in Detroit, Michigan. It is Michigan's third-largest university. Founded in 1868, Wayne State consists of 13 schools and colleges offering approximately 350 programs to nearly 25,000 ...
in
Detroit Detroit ( , ; , ) is the largest city in the U.S. state of Michigan. It is also the largest U.S. city on the United States–Canada border, and the seat of government of Wayne County. The City of Detroit had a population of 639,111 at th ...
. In October 1972, connections to the
CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
mainframe at
Michigan State University Michigan State University (Michigan State, MSU) is a public university, public Land-grant university, land-grant research university in East Lansing, Michigan. It was founded in 1855 as the Agricultural College of the State of Michigan, the fi ...
in
East Lansing East Lansing is a city in the U.S. state of Michigan. Most of the city lies within Ingham County with a smaller portion extending north into Clinton County. At the 2020 Census the population was 47,741. Located directly east of the state capital ...
completed the triad. Over the next several years, in addition to host-to-host interactive connections, the network was enhanced to support terminal-to-host connections, host-to-host batch connections (remote job submission, remote printing, batch file transfer), interactive file transfer, gateways to the
Tymnet Tymnet was an international data communications network headquartered in Cupertino, California that used virtual call packet-switched technology and X.25, SNA/ SDLC, BSC and Async interfaces to connect host computers (servers) at thousands of lar ...
and
Telenet Telenet was an American commercial packet-switched network which went into service in 1975. It was the first FCC-licensed public data network in the United States. Various commercial and government interests paid monthly fees for dedicated lines ...
public data network A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public p ...
s,
X.25 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 ...
host attachments, gateways to X.25 data networks,
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
attached hosts, and eventually
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
; additionally, public universities in Michigan joined the network. All of this set the stage for Merit's role in the
NSFNET 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 p ...
project starting in the mid-1980s.


NPL

In 1965,
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL). In 1965 he conceived of packet switching, which is today the dominant basis for data communic ...
of the
National Physical Laboratory (United Kingdom) The National Physical Laboratory (NPL) is the national measurement standards laboratory of the United Kingdom. It is one of the most extensive government laboratories in the UK and has a prestigious reputation for its role in setting and mainta ...
designed and proposed a national commercial data network based on packet switching. The proposal was not taken up nationally but, in 1966, he designed a
local network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
using "interface computers", today known as routers, to serve the needs of NPL and prove the feasibility of packet switching. By 1968 Davies had begun building the
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 Donal ...
to meet the needs of the multidisciplinary laboratory and prove the technology under operational conditions. In 1976, 12 computers and 75 terminal devices were attached, and more were added until the network was replaced in 1986. NPL and the ARPANET were the first two networks to use packet switching, and were interconnected in the early 1970s.


Octopus

Octopus was a local network at
Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
. It connected sundry hosts at the lab to interactive terminals and various computer peripherals including a bulk storage system.


Philips Research

Philips Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters i ...
Research Laboratories in
Redhill, Surrey Redhill () is a town in the borough of Reigate and Banstead within the county of Surrey, England. The town, which adjoins the town of Reigate to the west, is due south of Croydon in Greater London, and is part of the London commuter belt. The ...
developed a packet switching network for internal use. It was a datagram network with a single switching node.


PUP

PARC Universal Packet The PARC Universal Packet (commonly abbreviated to PUP or PuP, although the original documents usually use Pup) was one of the two earliest internetworking protocol suites; it was created by researchers at Xerox PARC in the mid-1970s. (Technicall ...
(PUP or Pup) was one of the two earliest
internetworking Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interco ...
protocol suite The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the ''suite'' is the definition of the communication protoc ...
s; it was created by researchers at
Xerox PARC PARC (Palo Alto Research Center; formerly Xerox PARC) is a research and development company in Palo Alto, California. Founded in 1969 by Jacob E. "Jack" Goldman, chief scientist of Xerox Corporation, the company was originally a division of Xero ...
in the mid-1970s. The entire suite provided
routing Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone netw ...
and packet delivery, as well as higher level functions such as a
reliable byte stream A reliable byte stream is a common service paradigm in computer networking; it refers to a byte stream in which the bytes which emerge from the communication channel at the recipient are exactly the same, and in exactly the same order, as they wer ...
, along with numerous applications. Further developments led to
Xerox Network Systems Xerox Network Systems (XNS) is a computer networking protocol suite developed by Xerox within the Xerox Network Systems Architecture. It provided general purpose network communications, internetwork routing and packet delivery, and higher level f ...
(XNS).


RCP

RCP was an experimental network created by the French PTT. It was used to gain experience with packet switching technology before the specification of TRANSPAC was frozen. RCP was a virtual-circuit network in contrast to CYCLADES which was based on
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 del ...
s. RCP emphasised terminal-to-host and terminal-to-terminal connection; CYCLADES was concerned with host-to-host communication. TRANSPAC was introduced as an X.25 network. RCP influenced the
X.25 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 ...
specification.


RETD

Red Especial de Transmisión de Datos (RETD) was a network developed by Compañía Telefónica Nacional de España. It became operational in 1972 and thus was the first public network.


SCANNET

"The experimental packet-switched Nordic telecommunication network SCANNET was implemented in Nordic technical libraries in the 1970s, and it included first Nordic electronic journal Extemplo. Libraries were also among first ones in universities to accommodate microcomputers for public use in the early 1980s."


SITA HLN

SITA Sita (; ) also called as Janaki and Vaidehi is a Hindu goddess and the female protagonist of the Hindu epic, ''Ramayana''. She is the consort of Rama, the avatar of the god Vishnu, and is regarded as a form of Vishnu's consort, Lakshmi. She ...
is a consortium of airlines. Its High Level Network (HLN) became operational in 1969 at about the same time as ARPANET. It carried interactive traffic and message-switching traffic. As with many non-academic networks, very little has been published about it.


SRCnet/SERCnet

A number of computer facilities serving the
Science Research Council The Science and Engineering Research Council (SERC) and its predecessor the Science Research Council (SRC) were the UK agencies in charge of publicly funded scientific and engineering research activities, including astronomy, biotechnology and bi ...
(SRC) community in the United Kingdom developed beginning in the early 1970s. Each had their own star network ( ULCC London, UMRCC Manchester,
Rutherford Appleton Laboratory The Rutherford Appleton Laboratory (RAL) is one of the national scientific research laboratories in the UK operated by the Science and Technology Facilities Council (STFC). It began as the Rutherford High Energy Laboratory, merged with the Atlas ...
). There were also regional networks centred on Bristol (on which work was initiated in the late 1960s) followed in the mid-late 1970s by Edinburgh, the Midlands and Newcastle. These groups of institutions
shared resources In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing ha ...
to provide better computing facilities than could be afforded individually. The networks were each based on one manufacturer's standards and were mutually incompatible and overlapping. In 1981, the SRC was renamed the
Science and Engineering Research Council The Science and Engineering Research Council (SERC) and its predecessor the Science Research Council (SRC) were the UK agencies in charge of publicly funded scientific and engineering research activities, including astronomy, biotechnology and bi ...
(SERC). In the early 1980s a standardisation and interconnection effort started, hosted on an expansion of the SERCnet research network and based on the
Coloured Book protocols The Coloured Book protocols were a set of communication protocols for computer networks developed in the United Kingdom in the 1970s. The name originated with each protocol being identified by the colour of the cover of its specification document. ...
, later evolving into
JANET Janet may refer to: Names * Janet (given name) * Janet (French singer) (1939–2011) Surname * Charles Janet (1849–1932), French engineer, inventor and biologist, known for the Left Step periodic table * Jules Janet (1861–1945), French psych ...
.


Systems Network Architecture

Systems Network Architecture Systems Network Architecture (SNA) is IBM's proprietary networking architecture, created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes formats and protocols but, in itself, is not a pi ...
(SNA) is IBM's proprietary networking architecture created in 1974. An IBM customer could acquire hardware and software from IBM and lease private lines from a common carrier to construct a private network.


Telenet

Telenet Telenet was an American commercial packet-switched network which went into service in 1975. It was the first FCC-licensed public data network in the United States. Various commercial and government interests paid monthly fees for dedicated lines ...
was the first FCC-licensed
public data network A public data network (PDN) is a network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the public. The first public p ...
in the United States. Telenet was incorporated in 1973 and started operations in 1975. It was founded by
Bolt Beranek & Newman Raytheon BBN (originally Bolt Beranek and Newman Inc.) is an American research and development company, based next to Fresh Pond in Cambridge, Massachusetts, United States. In 1966, the Franklin Institute awarded the firm the Frank P. Brown ...
with Larry Roberts as CEO as a means of making packet switching technology public. Telenet initially used a proprietary
virtual connection A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is established within the network between two endpoints. The network, rather than having a fixed data rate reservation ...
host interface, but changed the host interface to X.25 and the terminal interface to X.29. It went public in 1979 and was then sold to GTE.


Tymnet

Tymnet Tymnet was an international data communications network headquartered in Cupertino, California that used virtual call packet-switched technology and X.25, SNA/ SDLC, BSC and Async interfaces to connect host computers (servers) at thousands of lar ...
was an international data communications network headquartered in San Jose, CA that utilized virtual call packet switched technology and used X.25, SNA/SDLC, BSC and ASCII interfaces to connect host computers (servers) at thousands of large companies, educational institutions, and government agencies. Users typically connected via dial-up connections or dedicated
asynchronous serial Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal wit ...
connections. The business consisted of a large public network that supported dial-up users and a private network business that allowed government agencies and large companies (mostly banks and airlines) to build their own dedicated networks. The private networks were often connected via gateways to the public network to reach locations not on the private network. Tymnet was also connected to dozens of other public networks in the U.S. and internationally via X.25/X.75 gateways.


XNS

Xerox Network Systems Xerox Network Systems (XNS) is a computer networking protocol suite developed by Xerox within the Xerox Network Systems Architecture. It provided general purpose network communications, internetwork routing and packet delivery, and higher level f ...
(XNS) was a
protocol suite The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the ''suite'' is the definition of the communication protoc ...
promulgated by
Xerox Xerox Holdings Corporation (; also known simply as Xerox) is an American corporation that sells print and electronic document, digital document products and services in more than 160 countries. Xerox is headquartered in Norwalk, Connecticut (ha ...
, which provided
routing Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone netw ...
and packet delivery, as well as higher level functions such as a
reliable stream A reliable byte stream is a common service paradigm in computer networking; it refers to a byte stream in which the bytes which emerge from the communication channel at the recipient are exactly the same, and in exactly the same order, as they wer ...
, and
remote procedure call In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared network), which is coded as if it were a normal (l ...
s. It was developed from
PARC Universal Packet The PARC Universal Packet (commonly abbreviated to PUP or PuP, although the original documents usually use Pup) was one of the two earliest internetworking protocol suites; it was created by researchers at Xerox PARC in the mid-1970s. (Technicall ...
(PUP).


X.25 era

There were two kinds of X.25 networks. Some such as DATAPAC and TRANSPAC were initially implemented with an X.25 external interface. Some older networks such as TELENET and TYMNET were modified to provide a X.25 host interface in addition to older host connection schemes. DATAPAC was developed by
Bell-Northern Research Bell-Northern Research (BNR) was a telecommunications research and development company established In 1971 when Bell Canada and Nortel, Northern Electric combined their R&D organizations. It was jointly owned by Bell Canada and Nortel, Northern ...
which was a joint venture of
Bell Canada Bell Canada (commonly referred to as Bell) is a Canadian telecommunications company headquartered at 1 Carrefour Alexander-Graham-Bell in the borough of Verdun in Montreal, Quebec, Canada. It is an ILEC (incumbent local exchange carrier) in t ...
(a common carrier) and
Northern Telecom Northern may refer to the following: Geography * North, a point in direction * Northern Europe, the northern part or region of Europe * Northern Highland, a region of Wisconsin, United States * Northern Province, Sri Lanka * Northern Range, a r ...
(a telecommunications equipment supplier). Northern Telecom sold several DATAPAC clones to foreign PTTs including the
Deutsche Bundespost The Deutsche Bundespost (German federal post office) was a German state-run postal service and telecommunications business founded in 1947. It was initially the second largest federal employer during its time. After staff reductions in the 198 ...
.
X.75 X.75 is an International Telecommunication Union (ITU) (formerly CCITT) standard specifying the interface for interconnecting two X.25 X.25 is an ITU-T standard protocol suite for packet-switched data communication in wide area networks (WAN). ...
and
X.121 X.121 is the ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between Public Data Networks (PDNs), connecting two network user addresses (NUAs). It consists of a maximum of fourteen ...
allowed the interconnection of national X.25 networks. A user or host could call a host on a foreign network by including the DNIC of the remote network as part of the destination address.


AUSTPAC

AUSTPAC AUSTPAC was a public X.25 network operated by Telstra. Started by Telecom Australia in 1982, AUSTPAC was Australia's first public packet-switched data network, supporting applications such as online betting, financial applications (the Australian ...
was an Australian public X.25 network operated by
Telstra Telstra Group Limited is an Australian telecommunications company that builds and operates telecommunications networks and markets voice, mobile, internet access, pay television and other products and services. It is a member of the S&P/ASX 20 ...
. Started by
Telecom Australia Telstra Group Limited is an Australian telecommunications company that builds and operates telecommunications networks and markets voice, mobile, internet access, pay television and other products and services. It is a member of the S&P/ASX 20 ...
in the early 1980s, AUSTPAC was Australia's first public packet-switched data network and supported applications such as on-line betting, financial applications—the
Australian Tax Office The Australian Taxation Office (ATO) is an Australian statutory agency and the principal revenue collection body for the Australian Government. The ATO has responsibility for administering the Australian federal taxation system, superannuati ...
made use of AUSTPAC—and remote terminal access to academic institutions, who maintained their connections to AUSTPAC up until the mid-late 1990s in some cases. Access was via a dial-up terminal to a PAD, or, by linking a permanent X.25 node to the network.


ConnNet

ConnNet ConnNet was a packet switched data network operated by the Southern New England Telephone Company serving the U.S. state of Connecticut. ConnNet was the nation's first local public packet switching network when it was launched on March 11, 1985. U ...
was a network operated by the
Southern New England Telephone Company The Southern New England Telephone Company (commonly referred to as SNETCo by its customers), doing business as Frontier Communications of Connecticut, is a local exchange carrier owned by Frontier Communications. History It started operations o ...
serving the state of Connecticut. Launched on March 11, 1985, it was the first local public packet-switched network in the United States.


Datanet 1

Datanet 1 was the public switched data network operated by the Dutch PTT Telecom (now known as
KPN KPN (in full Koninklijke KPN N.V., also Royal KPN N.V.) is a Dutch landline and mobile telecommunications company. KPN originated from a government-run postal, telegraph and telephone service and is based in Rotterdam, Netherlands. History Un ...
). Strictly speaking Datanet 1 only referred to the network and the connected users via
leased line A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by ...
s (using the
X.121 X.121 is the ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between Public Data Networks (PDNs), connecting two network user addresses (NUAs). It consists of a maximum of fourteen ...
DNIC 2041), the name also referred to the public PAD service ''Telepad'' (using the DNIC 2049). And because the main
Videotex Videotex (or interactive videotex) was one of the earliest implementations of an end-user information system. From the late 1970s to early 2010s, it was used to deliver information (usually pages of text) to a user in computer-like format, typi ...
service used the network and modified PAD devices as infrastructure the name Datanet 1 was used for these services as well.


DATAPAC

DATAPAC was the first operational X.25 network (1976). It covered major Canadian cities and was eventually extended to smaller centers.


Datex-P

Deutsche Bundespost operated the Datex-P national network in Germany. The technology was acquired from Northern Telecom.


Eirpac

Eirpac EIRPAC is Ireland's packet switched X.25 data network. It replaced Euronet (telecommunications network), Euronet in 1984. Eirpac uses the Data Network Identification Code, DNIC 2724. HEAnet was first in operation via X.25 4.8Kb Eirpac connection ...
is the Irish public switched data network supporting
X.25 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
X.28 X.28 is an ITU-T standard specifying the interface between asynchronous character-mode data terminal equipment (DTE), such as computer terminals, and a Packet Assembler/Disassembler (PAD) that connects the DTE to a packet switched network such as a ...
. It was launched in 1984, replacing Euronet. Eirpac is run by
Eircom Eircom Limited, trading as Eir ( ; stylised eir), is a large fixed, mobile and broadband telecommunications company in Ireland. The now privatised company, which is currently incorporated in Jersey, traces its origins to the Ireland's former ...
.


Euronet

Nine member states of the
European Economic Community The European Economic Community (EEC) was a regional organization created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisb ...
contracted with
Logica Logica plc was a multinational IT and management consultancy company headquartered in London and later Reading, United Kingdom. Founded in 1969, the company had offices in London and in a number of major cities across England, Wales and Scotl ...
and the French company SESA to set up a joint venture in 1975 to undertake the ''Euronet'' development, using X.25 protocols to form virtual circuits. It was to replace EIN and established a network in 1979 linking a number of European countries until 1984 when the network was handed over to national PTTs.


HIPA-NET

Hitachi () is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
designed a private network system for sale as a turnkey package to multi-national organizations. In addition to providing X.25 packet switching, message switching software was also included. Messages were buffered at the nodes adjacent to the sending and receiving terminals. Switched virtual calls were not supported, but through the use of ''logical ports'' an originating terminal could have a menu of pre-defined destination terminals.


Iberpac

Iberpac Iberpac (or Red UNO) was the Spanish packet switched X.25 data network. It was operated by Telefónica España, the incumbent Spanish telecommunications operator. Iberpac lents its name to Iberpac Plus and Iberpac Básico, the latest X.25 services ...
is the Spanish public packet-switched network, providing X.25 services. It was based on RETD which was operational since 1972. Iberpac was run by Telefonica.


IPSS

In 1978, X.25 provided the first international and commercial packet-switching network, the
International Packet Switched Service The International Packet Switched Service (IPSS) was the first international and commercial packet switching network. It was created in 1978 by a collaboration between Britain's Post Office Telecommunications, and the United States' Western Union In ...
(IPSS).


JANET

JANET Janet may refer to: Names * Janet (given name) * Janet (French singer) (1939–2011) Surname * Charles Janet (1849–1932), French engineer, inventor and biologist, known for the Left Step periodic table * Jules Janet (1861–1945), French psych ...
was the UK academic and research network, linking all universities, higher education establishments, and publicly funded research laboratories following its launch in 1984. The X.25 network, which used the
Coloured Book protocols The Coloured Book protocols were a set of communication protocols for computer networks developed in the United Kingdom in the 1970s. The name originated with each protocol being identified by the colour of the cover of its specification document. ...
, was based mainly on
GEC 4000 series The GEC 4000 was a series of 16/ 32-bit minicomputers produced by GEC Computers Ltd in the United Kingdom during the 1970s, 1980s and early 1990s. History GEC Computers was formed in 1968 as a business unit of the GEC conglomerate. It ...
switches, and ran X.25 links at up to 8 Mbit/s in its final phase before being converted to an IP-based network in 1991. The JANET network grew out of the 1970s SRCnet, later called SERCnet.


PSS

Packet Switch Stream In the United Kingdom, Packet Switch Stream (PSS) was an X.25-based packet-switched network, provided by the British Post Office Telecommunications and then British Telecommunications starting in 1980. After a period of pre-operational testing with ...
(PSS) was the
Post Office Telecommunications Post Office Telecommunications was set up as a separate department of the UK Post Office, in October 1969. The Post Office Act 1969 was passed to provide for greater efficiency in post and telephone services; rather than run a range of services, ...
(later to become
British Telecom BT Group plc (trade name, trading as BT and formerly British Telecom) is a British Multinational corporation, multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is th ...
) national X.25 network with a DNIC of 2342. British Telecom renamed PSS Global Network Service (GNS), but the PSS name has remained better known. PSS also included public dial-up PAD access, and various InterStream gateways to other services such as Telex.


REXPAC

REXPAC was the nationwide experimental packet switching data network in Brazil, developed by the research and development center of
Telebrás Telebras is a Brazilian telecommunications company which was the state-owned monopoly telephone system. It was broken up in July 1998 into twelve separate companies, nicknamed the 'Baby Bras' companies, that were auctioned to private bidders. The ...
, the state-owned public telecommunications provider.


TRANSPAC

TRANSPAC was the national X.25 network in France. It was developed locally at about the same time as DATAPAC in Canada. The development was done by the French PTT and influenced by the experimental RCP network. It began operation in 1978, and served commercial users and, after
Minitel The Minitel was a videotex online service accessible through telephone lines, and was the world's most successful online service prior to the World Wide Web. It was invented in Cesson-Sévigné, near Rennes in Brittany, France. The service was ...
began, consumers.


UNINETT

UNINETT was a wide-area Norwegian packet-switched network established through a joint effort between Norwegian universities, research institutions and the Norwegian Telecommunication administration. The original network was based on X.25; Internet protocols were adopted later.


VENUS-P

VENUS-P was an international X.25 network that operated from April 1982 through March 2006. At its subscription peak in 1999, VENUS-P connected 207 networks in 87 countries.


Venepaq

Venepaq is the national X.25 public network in Venezuela. It is run by
Cantv CANTV () is the state-run telephone and internet service provider in Venezuela. It was one of the first telephone service enterprises in the country, founded in 1930. The largest telecommunications provider in Venezuela, it was privatized in 19 ...
and allows direct and dial-up connections. Venepaq provides nationwide access at low cost. It provides national and international access and allows connection from 19.2 to in direct connections, and 1200, 2400 and in dial-up connections.


Internet era

When
Internet 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, pub ...
connectivity was made available to anyone who could pay for an
ISP An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise private ...
subscription, the distinctions between national networks blurred. The user no longer saw network identifiers such as the DNIC. Some older technologies such as
circuit switching Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel ( circuit) through the network before the nodes may communicate. The circuit guarantees the full b ...
have resurfaced with new names such as
fast packet switching In telecommunications, fast packet switching is a variant of packet switching that increases the throughput by eliminating overhead associated with flow control and error correction functions, which are either offloaded to upper layer networking p ...
. Researchers have created some experimental networks to complement the existing Internet.


CSNET

The Computer Science Network (CSNET) was a computer network funded by the U.S. National Science Foundation (NSF) that began operation in 1981. Its purpose was to extend networking benefits, for
computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
departments at academic and research institutions that could not be directly connected to
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 fou ...
, due to funding or authorization limitations. It played a significant role in spreading awareness of, and access to, national networking and was a major milestone on the path to development of the global
Internet 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, pub ...
.


Internet2

Internet2 Internet2 is a not-for-profit United States computer networking consortium led by members from the research and education communities, industry, and government. The Internet2 consortium administrative headquarters are located in Ann Arbor, Mi ...
is a not-for-profit United States
computer network A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
ing
consortium A consortium (plural: consortia) is an association of two or more individuals, companies, organizations or governments (or any combination of these entities) with the objective of participating in a common activity or pooling their resources for ...
led by members from the research and education communities, industry, and government. The Internet2 community, in partnership with
Qwest Qwest Communications International, Inc. was a United States telecommunications carrier. Qwest provided local service in 14 western and midwestern U.S. states: Arizona, Colorado, Idaho, Iowa, Minnesota, Montana, Nebraska, New Mexico, North Dako ...
, built the first Internet2 Network, called Abilene, in 1998 and was a prime investor in the
National LambdaRail National LambdaRail (NLR) was a , high-speed national computer network owned and operated by the U.S. research and education community. In November 2011, the control of NLR was purchased from its university membership by a billionaire Patrick Soon ...
(NLR) project. In 2006, Internet2 announced a partnership with
Level 3 Communications Level 3 Communications was an American multinational telecommunications and Internet service provider company headquartered in Broomfield, Colorado. It ultimately became a part of CenturyLink (now Lumen Technologies), where Level 3 President ...
to launch a brand new nationwide network, boosting its capacity from 10 Gbit/s to 100 Gbit/s. In October, 2007, Internet2 officially retired Abilene and now refers to its new, higher capacity network as the Internet2 Network.


NSFNET

The National Science Foundation Network (NSFNET) was a program of coordinated, evolving projects sponsored by the
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...
(NSF) beginning in 1985 to promote advanced research and education networking in the United States. NSFNET was also the name given to several nationwide backbone networks operating at speeds of 56 kbit/s, 1.5 Mbit/s (T1), and 45 Mbit/s (T3) that were constructed to support NSF's networking initiatives from 1985-1995. Initially created to link researchers to the nation's NSF-funded supercomputing centers, through further public funding and private industry partnerships it developed into a major part of the
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-ca ...
.


NSFNET regional networks

In addition to the five NSF supercomputer centers, NSFNET provided connectivity to eleven regional networks and through these networks to many smaller regional and campus networks in the United States. The NSFNET regional networks were: *BARRNet, the Bay Area Regional Research Network in
Palo Alto, California Palo Alto (; Spanish language, Spanish for "tall stick") is a charter city in the northwestern corner of Santa Clara County, California, United States, in the San Francisco Bay Area, named after a Sequoia sempervirens, coastal redwood tree kno ...
; *CERFNET,
California Education and Research Federation Network The California Education and Research Federation Network (CERFnet) is a mid-level network service provider based in California. CERFnet was one of the NSFNET regional networks and a co-founder of the Commercial Internet eXchange (CIX). The CERFnet n ...
in
San Diego, California San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...
, serving California and Nevada; *CICNet, the
Committee on Institutional Cooperation The Big Ten Academic Alliance (BTAA), formerly the Committee on Institutional Cooperation (CIC), is the academic consortium of the universities in the Big Ten Conference. The consortium was renamed on June 29, 2016. Member universities The Bi ...
Network via the Merit Network in
Ann Arbor, Michigan Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County, Michigan, Washtenaw County. The 2020 United States census, 2020 census recorded its population to be 123,851. It is the principal city of the Ann Arbor ...
and later as part of the T3 upgrade via
Argonne National Laboratory Argonne National Laboratory is a science and engineering research United States Department of Energy National Labs, national laboratory operated by University of Chicago, UChicago Argonne LLC for the United States Department of Energy. The facil ...
outside of
Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...
, serving the
Big Ten The Big Ten Conference (stylized B1G, formerly the Western Conference and the Big Nine Conference) is the oldest Division I collegiate athletic conference in the United States. Founded as the Intercollegiate Conference of Faculty Representati ...
Universities and the
University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...
in Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin; * Merit/MichNet in
Ann Arbor, Michigan Ann Arbor is a city in the U.S. state of Michigan and the county seat of Washtenaw County, Michigan, Washtenaw County. The 2020 United States census, 2020 census recorded its population to be 123,851. It is the principal city of the Ann Arbor ...
serving Michigan, formed in 1966, still in operation as of 2016; *MIDnet in
Lincoln, Nebraska Lincoln is the capital city of the U.S. state of Nebraska and the county seat of Lancaster County. The city covers with a population of 292,657 in 2021. It is the second-most populous city in Nebraska and the 73rd-largest in the United Sta ...
serving Arkansas, Iowa, Kansas, Missouri, Nebraska, Oklahoma, and South Dakota; * NEARNET, the New England Academic and Research Network in
Cambridge, Massachusetts Cambridge ( ) is a city in Middlesex County, Massachusetts, United States. As part of the Boston metropolitan area, the cities population of the 2020 U.S. census was 118,403, making it the fourth most populous city in the state, behind Boston, ...
, added as part of the upgrade to T3, serving Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont, established in late 1988, operated by BBN under contract to MIT, BBN assumed responsibility for NEARNET on 1 July 1993; *NorthWestNet in
Seattle, Washington Seattle ( ) is a port, seaport city on the West Coast of the United States. It is the county seat, seat of King County, Washington, King County, Washington (state), Washington. With a 2020 population of 737,015, it is the largest city in bo ...
, serving Alaska, Idaho, Montana, North Dakota, Oregon, and Washington, founded in 1987; *
NYSERNet NYSERNet (New York State Education and Research Network) is a non-profit Internet Service Provider in New York State. It mainly provides Internet access to universities, colleges, museums, health care facilities, primary and secondary schools, and r ...
, New York State Education and Research Network in
Ithaca, New York Ithaca is a city in the Finger Lakes region of New York, United States. Situated on the southern shore of Cayuga Lake, Ithaca is the seat of Tompkins County and the largest community in the Ithaca metropolitan statistical area. It is named a ...
; *JVNCNet, the John von Neumann National Supercomputer Center Network in
Princeton, New Jersey Princeton is a municipality with a borough form of government in Mercer County, in the U.S. state of New Jersey. It was established on January 1, 2013, through the consolidation of the Borough of Princeton and Princeton Township, both of whi ...
, serving Delaware and New Jersey; *SESQUINET, the Sesquicentennial Network in
Houston, Texas Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 in ...
, founded during the 150th anniversary of the State of
Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...
; * SURAnet, the Southeastern Universities Research Association network in
College Park, Maryland College Park is a city in Prince George's County, Maryland, United States, and is approximately four miles (6.4 km) from the northeast border of Washington, D.C. The population was 34,740 at the 2020 United States Census. It is best known a ...
and later as part of the T3 upgrade in
Atlanta, Georgia Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,715 ...
serving Alabama, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia, sold to BBN in 1994; and *Westnet in
Salt Lake City, Utah Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the Capital (political), capital and List of cities and towns in Utah, most populous city of Utah, United States. It is the county seat, seat of Salt Lake County, Utah, Sal ...
and
Boulder, Colorado Boulder is a home rule city that is the county seat and most populous municipality of Boulder County, Colorado, United States. The city population was 108,250 at the 2020 United States census, making it the 12th most populous city in Color ...
, serving Arizona, Colorado, New Mexico, Utah, and Wyoming.


National LambdaRail

The
National LambdaRail National LambdaRail (NLR) was a , high-speed national computer network owned and operated by the U.S. research and education community. In November 2011, the control of NLR was purchased from its university membership by a billionaire Patrick Soon ...
was launched in September 2003. It is a 12,000-mile high-speed national computer network owned and operated by the U.S. research and education community that runs over fiber-optic lines. It was the first transcontinental
10 Gigabit Ethernet 10 Gigabit Ethernet (10GE, 10GbE, or 10 GigE) is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlike previous Eth ...
network. It operates with high aggregate capacity of up to 1.6 Tbit/s and a high 40 Gbit/s bitrate, with plans for 100 Gbit/s. The upgrade never took place and NLR ceased operations in March 2014.


TransPAC, TransPAC2, and TransPAC3

TransPAC2 The TransPAC2 Network was a US National Science Foundation-funded high-speed international computer network circuit connecting national research and education networks in the Asia-Pacific region to those in the US. It was the continuation of the ...
and TransPAC3, continuations of the TransPAC project, a high-speed international Internet service connecting research and education networks in the Asia-Pacific region to those in the US. TransPAC is part of the NSF's International Research Network Connections (IRNC) program.


Very high-speed Backbone Network Service (vBNS)

The
Very high-speed Backbone Network Service The very high-speed Backbone Network Service (vBNS) came on line in April 1995 as part of a National Science Foundation (NSF) sponsored project to provide high-speed interconnection between NSF-sponsored supercomputing centers and select access po ...
(vBNS) came on line in April 1995 as part of a
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...
(NSF) sponsored project to provide high-speed interconnection between NSF-sponsored
supercomputing A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second (FLOPS) instead of million instructions ...
centers and select access points in the United States. The network was engineered and operated by MCI Telecommunications under a cooperative agreement with the NSF. By 1998, the vBNS had grown to connect more than 100 universities and research and engineering institutions via 12 national points of presence with
DS-3 A Digital Signal 3 (DS3) is a digital signal level 3 T-carrier. It may also be referred to as a T3 line. *The data rate for this type of signal is 44.736 Mbit/s (45 Mb). *DS3 uses 75ohm coaxial cable and BNC connectors. *This level of carrier can ...
(45 Mbit/s),
OC-3c Optical Carrier transmission rates are a standardized set of specifications of transmission bandwidth for digital signals that can be carried on Synchronous Optical Networking (SONET) fiber optic networks. Transmission rates are defined by rate of ...
(155 Mbit/s), and OC-12c (622 Mbit/s) links on an all OC-12c backbone, a substantial engineering feat for that time. The vBNS installed one of the first ever production OC-48c (2.5 Gbit/s) IP links in February 1999 and went on to upgrade the entire backbone to OC-48c. In June 1999 MCI WorldCom introduced vBNS+ which allowed attachments to the vBNS network by organizations that were not approved by or receiving support from NSF. After the expiration of the NSF agreement, the vBNS largely transitioned to providing service to the government. Most universities and research centers migrated to the Internet2 educational backbone. In January 2006, when MCI and
Verizon Verizon Communications Inc., commonly known as Verizon, is an American multinational telecommunications conglomerate and a corporate component of the Dow Jones Industrial Average. The company is headquartered at 1095 Avenue of the Americas in ...
merged, vBNS+ became a service of
Verizon Business Verizon Business (formerly known as Verizon Enterprise Solutions) is a division of Verizon Communications based in Basking Ridge, New Jersey that provides services and products for Verizon's business and government clients around the world. It ...
.


See also

*
Multi-bearer network A multi-bearer network, or an MBN, is a network having the capability to carry a data packet via one of several alternative bearers. To be more precise, the term ''multi-bearer network'' should be interpreted as meaning ‘multi-bearer-type network ...
*
Optical burst switching Optical burst switching (OBS) is an optical networking technique that allows dynamic sub-wavelength switching of data. OBS is viewed as a compromise between the yet unfeasible full optical packet switching (OPS) and the mostly static optical circui ...
*
Packet radio In digital radio, packet radio is the application of packet switching techniques to digital radio communications. Packet radio uses a packet switching protocol as opposed to circuit switching or message switching protocols to transmit digital dat ...
*
Public switched data network A public data network (PDN) is a telecommunications network, network established and operated by a telecommunications administration, or a recognized private operating agency, for the specific purpose of providing data transmission services for the ...
*
Time-Driven Switching In Telecommunication and Computer networking, time-driven switching (TDS) is a node by node time variant implementation of Circuit switching, where the propagating datagram is shorter in space than the distance between source and destination. With T ...
- a bufferless approach to packet switching *
Transmission delay In a network based on packet switching, transmission delay (or store-and-forward delay, also known as packetization delay) is the amount of time required to push all the packet's bits into the wire. In other words, this is the delay caused by the ...
*
Virtual private network A virtual private network (VPN) extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. The be ...


References


Bibliography

*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 The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...
Transactions on Communications Systems, Vol. CS-12 No. 1, pp. 1–9, 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) *Lawrence Roberts,
The Evolution of Packet Switching
' (Proceedings of the IEEE, November, 1978)


Further reading

* *Hafner, Katie ''Where Wizards Stay Up Late'' (Simon and Schuster, 1996) pp 52–67 *Norberg, Arthur; O'Neill, Judy E. ''Transforming Computer Technology: Information Processing for the Pentagon, 1962-1982'' (Johns Hopkins University, 1996)


External links

*
Oral history interview with Paul Baran
Charles Babbage Institute The IT History Society (ITHS) is an organization that supports the history and scholarship of information technology by encouraging, fostering, and facilitating archival and historical research. Formerly known as the Charles Babbage Foundation, ...
University of Minnesota, Minneapolis. Baran describes his working environment at RAND, as well as his initial interest in survivable communications, and the evolution, writing and distribution of his eleven-volume work, "On Distributed Communications". Baran discusses his interaction with the group at ARPA who were responsible for the later development of the ARPANET.
NPL Data Communications Network
NPL video, 1970s

site reviewed by Baran, Roberts, and Kleinrock
20+ articles on packet switching in the 1970s


{{DEFAULTSORT:Packet Switching Computer networking History of the Internet Network protocols