A public data network (PDN) is a

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 Mathematic ...

established and operated by a

telecommunications 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 ...

administration, or a recognized private operating agency, for the specific purpose of providing

data transmission Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point or ...

services for the public. The first public packet switching network, RETD, was deployed in 1972 in Spain. "Public data network" was the common name given to the collection 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 a ...

providers, the first of which was DATAPAC in 1976. 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 ...

became the first commercial and international packet-switched network in 1978. Their combined networks had large global coverage during the 1980s and into the 1990s. These networks later provided the infrastructure for the early

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, p ...

Description

In communications, a PDN is a circuit- or

packet-switched In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the pack ...

network that is available to the public and that can transmit data in digital form. A PDN provider is a company that provides access to a PDN and that provides any of

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 ...

, or cell relay ( ATM) services. Access to a PDN generally includes a guaranteed bandwidth, known as the

committed information rate In a Frame Relay network, committed information rate (CIR) is the bandwidth for a virtual circuit guaranteed by an internet service provider to work under normal conditions. Committed data rate (CDR) is the payload portion of the CIR. At any gi ...

(CIR). Costs for the access depend on the guaranteed rate. PDN providers differ in how they charge for temporary increases in required bandwidth (known as surges). Some use the amount of overrun; others use the surge duration.

History

Experimental packet switching networks preceded the first public data networks which came into operation in the 1970s. Early examples include: RETD/

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 ...

in Spain, which was the first PDN in 1972; RCP/ Transpac in France; Telenet, Tymnet and

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 ...

in the United States; EPSS/ Packet Switch Stream, in the United Kingdom; EIN/ Euronet in the

EEC 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 Lis ...

; DATAPAC in Canada, which was the first PDN to use X.25; and

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 Australia ...

in Australia. The

was the first commercial and international packet-switched network. It was a collaboration between British and American telecom companies that became operational in 1978. These networks later adopted

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 su ...

and provided the infrastructure for the early

Public switched data network

A public switched data network (PSDN) is a network for providing data services via a system of multiple

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, u ...

s, similar in concept to the

public switched telephone network The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local telep ...

(PSTN). A PSDN may use a variety of switching technologies, including

packet switching In telecommunications, packet switching is a method of grouping data into '' packets'' that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the p ...

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 ...

, and message switching. A packet-switched PSDN may also be called a packet-switched data network. Originally the term PSDN referred only to Packet Switch Stream (PSS), an

-based packet-switched network, mostly used to provide leased-line connections between

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 large ...

s and the Internet using permanent virtual circuits (PVCs). Today, the term may refer not only to Frame Relay and

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), both providing PVCs, but also to

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),

GPRS General Packet Radio Service (GPRS) is a packet oriented mobile data standard on the 2G and 3G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Ins ...

, and other packet-switching techniques. Whilst there are several technologies that are superficially similar to the PSDN, such as

Integrated Services Digital Network Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...

(ISDN) and the

digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric dig ...

(DSL) technologies, they are not examples of it. ISDN utilizes the PSTN circuit-switched network, and DSL uses point-to-point

communications overlaid on the PSTN local loop (copper wires), usually utilized for access to a packet-switched broadband IP network.

Public data transmission service

A public data transmission service is a

service that is established and operated by a

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 ...

administration Administration may refer to: Management of organizations * Management, the act of directing people towards accomplishing a goal ** Administrative Assistant, traditionally known as a Secretary, or also known as an administrative officer, admini ...

, or a recognized private operating agency, and uses a ''public data network''. A public data transmission service may include

Circuit Switched Data In communications, Circuit Switched Data (CSD) is the original form of data transmission developed for the time-division multiple access (TDMA)-based mobile phone systems like Global System for Mobile Communications (GSM). After 2010 many telec ...

, and

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 ...

data transmission.

Description

History

Public switched data network

Public data transmission service

See also

References

Further reading