Packet switched network
Encyclopedia
A packet-switched network is a digital communications network that groups all transmitted data, irrespective of content, type, or structure into suitably sized blocks, called packets. The network over which packets are transmitted is a shared network which routes each packet independently from all others and allocates transmission resources as needed.
The principal goals of packet switching
are to optimize utilization of available link capacity, minimize response times and increase the robustness of communication. When traversing network adapters, switches and other network nodes, packets are buffered and queued, resulting in variable delay and throughput, depending on the traffic load in the network.
The history of such networks can be divided into three eras: early networks before the introduction of X.25
and the OSI model
, the X.25 era when many postal, telephone and telegraph (PTT) companies introduced networks with X.25 interfaces, and the Internet era when restrictions on connection to the Internet were removed.
is the best known example of a host to datagram protocol. In the virtual call
system, the network guarantees sequenced delivery of data to the host. This results in a simpler host interface with less functionality than in the datagram model. X.25 is the best known virtual call protocol.
Inexpensive minicomputer
s were an important component in the early networks. In some cases custom I/O devices were added to allow inexpensive or exotic attachments to communication lines.
which eventually became the Internet.
was the principal designer. Some ideas from this network were later incorporated into ARPANET.
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, Phoenix, Chicago, and Phoenix) to facilitate a computer time-sharing service, apparently the world's first commercial online service. (In addition to selling GE computers, the centers were computer service bureaus, offering batch processing services. They lost money from the beginning, and Sinback, a high-level marketing manager, was given the job of turning the business around. He decided that a time-sharing system, based on Kemney's work at Dartmouth—which used a computer on loan from GE—could be profitable. Warner was right.)
After going international some years later, GEIS created a network data center near Cleveland, Ohio. Very little has been published about the internal details of their network. (Though it has been stated by some that Tymshare
copied the GEIS system to create their network, Tymnet
.) The design was hierarchal with redundant communication links.
to serve their time-sharing customers. It became operational in May 1976.
of the National Physical Laboratory, UK
made many important contributions to the theory of packet switching. NPL built a single node network to connect sundry hosts at NPL.
. It connected sundry hosts at the lab to interactive terminals and various computer peripherals including a bulk storage system.
Research Laboratories in Redhill, Surrey
developed a packet switching network for internal use. It was a datagram network with a single switching node.
in the mid-1970s. The entire suite provided routing
and packet delivery, as well as higher level functions such as a reliable byte stream
, along with numerous applications. Further developments led to Xerox Network Systems (XNS).
network in contrast to CYCLADES which was based on datagrams
. 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 specification of X.25
is a consortium of airlines. Their High Level Network 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.
(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. This allowed construction of a private network.
in the United States. It was founded by former ARPA IPTO director Larry Roberts as a means of making ARPANET technology public. He had tried to interest AT&T in buying the technology, but the monopoly's reaction was that this was incompatible with their future. Bolt, Beranack and Newman (BBN) provided the financing.
It initially used ARPANET technology but changed the host interface to X.25 and the terminal interface to X.29. Telenet designed these protocols and helped standardize them in the CCITT. Telenet was incorporated in 1973 and started operations in 1975. It went public in 1979 and was then sold to GTE.
, which provided routing
and packet delivery, as well as higher level functions such as a reliable stream, and remote procedure call
s. It was developed from PARC Universal Packet
(PUP).
(a common carrier) and Northern Telecom (a telecommunications equipment supplier). Northern Telecom sold several DATAPAC clones to foreign PTTs including the Deutsche Bundespost
. X.75
and X.121
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.
was an Australian public X.25 network operated by Telstra
. Started by Telecom Australia
in the early 1980s, AUSTPAC was Australia's first public packet-switched data network, supporting applications such as on-line betting, financial applications — the Australian Tax Office 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 can be via a dial-up terminal to a PAD
, or, by linking a permanent X.25 node to the network.
was a packet switched data network operated by the Southern New England Telephone Company serving the state of Connecticut.
PTT Telecom (now known as KPN
). Strictly speaking Datanet 1 only referred to the network and the connected users via leased line
s (using the X.121
DNIC 2041), the name also referred to the public PAD
service Telepad (using the DNIC 2049). And because the main Videotex
service used the network and modified PAD
devices as infrastructure
the name Datanet 1 was used for these services as well. Although this use of the name was incorrect all these services were managed by the same people within one department of KPN
contributed to the confusion.
was the first operational X.25 network (1976). It covered major Canadian cities and was eventually extended to smaller centres.
is the Irish public switched data network supporting X.25
and X.28
. It was launched in 1984, replacing Euronet. Eirpac is run by Eircom
.
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.
services. Iberpac is run by Telefonica
.
was the UK academic and research network, linking all universities, higher education establishments, publicly funded research laboratories. The X.25 network was based mainly on GEC 4000 series
switches, and run X.25 links at up to 8 Mbit/s in its final phase before being converted to an IP based network. The JANET network grew out of the 1970s SRCnet (later called SERCnet) network.
was the UK Post Office (later to become British Telecom) national X.25 network with a DNIC of 2342. British Telecom renamed PSS under its GNS (Global Network Service) name, 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.
and allow direct connection and dial up connections. Provides nationalwide access at very low cost. It provides national and international access. Venepaq allow conection from 19.2 Kbps to 64 Kbps in direct connections, and 1200, 2400 and 9600 bps in dial up connections. For more information, call (toll free) 0-800-EMPRESA (3677372) inside Venezuela from any land phone.
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
have resurfaced with new names such as fast packet switching
. Researchers have created some experimental networks to complement the existing Internet.
.
The principal goals of packet switching
Packet switching
Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams over a shared network...
are to optimize utilization of available link capacity, minimize response times and increase the robustness of communication. When traversing network adapters, switches and other network nodes, packets are buffered and queued, resulting in variable delay and throughput, depending on the traffic load in the network.
The history of such networks can be divided into three eras: early networks before the introduction of X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
and the OSI model
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
, the X.25 era when many postal, telephone and telegraph (PTT) companies introduced networks with X.25 interfaces, and the Internet era when restrictions on connection to the Internet were removed.
Early networks
ARPANET and SITA HLN became operational in 1969. Before the introduction of X.25 in 1973 , about twenty different network technologies were developed. There was a debate about the merits of two drastically different views as to proper division of labor between the hosts and the network. In the datagram system the host must detect loss or duplication of packets. Transmission Control Protocol /Internet Protocol (TCP/IP)Internet protocol suite
The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP from its most important protocols: Transmission Control Protocol and Internet Protocol , which were the first networking protocols defined in this...
is the best known example of a host to datagram protocol. In the virtual call
Virtual call capability
In telecommunication, a virtual call capability, sometimes called a virtual call facility, is a service feature in which:*a call set-up procedure and a call disengagement procedure determine the period of communication between two data terminal equipments in which user data are transferred by the...
system, the network guarantees sequenced delivery of data to the host. This results in a simpler host interface with less functionality than in the datagram model. X.25 is the best known virtual call protocol.
Inexpensive minicomputer
Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s were an important component in the early networks. In some cases custom I/O devices were added to allow inexpensive or exotic attachments to communication lines.
ARPANET
This is the principal survivor from the early era. TCP/IP, which was an important component of ARPANET2, was chosen for use in NSFNETNSFNet
The National Science Foundation Network was a program of coordinated, evolving projects sponsored by the National Science Foundation beginning in 1985 to promote advanced research and education networking in the United States...
which eventually became the Internet.
BNRNET
BNRNET was a network which Bell Northern Research 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 project.CYCLADES
CYCLADES was an experimental French network. Louis PouzinLouis Pouzin
Louis Pouzin invented the datagram and designed an early packet communications network, CYCLADES...
was the principal designer. Some ideas from this network were later incorporated into ARPANET.
DDX-1
This was an experimental network from Nippon PTT. It mixed circuit switching and packet switching. It was succeeded by DDX-2.EIN nee COST II
European Informatics Network was a project to link several national networks. It became operational in 1976.EPSS
EPSS (Experimental Packet Switching System) was an experiment of the UK Post Office. Ferranti supplied the hardware and software. The handling of link control messages (acknowledgements and flow control) was differed from that of most another networks and is not fully explained in the published literature.GEIS
As General Electric Information Services (GEIS), General ElectricGeneral Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
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, Phoenix, Chicago, and Phoenix) to facilitate a computer time-sharing service, apparently the world's first commercial online service. (In addition to selling GE computers, the centers were computer service bureaus, offering batch processing services. They lost money from the beginning, and Sinback, a high-level marketing manager, was given the job of turning the business around. He decided that a time-sharing system, based on Kemney's work at Dartmouth—which used a computer on loan from GE—could be profitable. Warner was right.)
After going international some years later, GEIS created a network data center near Cleveland, Ohio. Very little has been published about the internal details of their network. (Though it has been stated by some that Tymshare
Tymshare
Tymshare, Inc. was headquartered in Cupertino, California from 1964 to 1984.It was a well-known timesharing service and third-party hardware maintenance company throughout its history and competed with companies such as Four Phase, Compuserve, and Digital Equipment Corporation...
copied the GEIS system to create their network, Tymnet
Tymnet
Tymnet was an international data communications network headquartered in San Jose, California that used virtual call packet switched technology and X.25, SNA/SDLC, ASCII and BSC interfaces to connect host computers at thousands of large companies, educational institutions, and government agencies....
.) The design was hierarchal with redundant communication links.
IPSANET
IPSANET was a semi-private network constructed by I. P. Sharp AssociatesI. P. Sharp Associates
I. P. Sharp Associates, IPSA for short, was a major Canadian computer time sharing, consulting and services firm of the 1970s and 80s. IPSA is particularly well known for its work on the APL programming language, an early packet switching computer network known as IPSANET, and a powerful...
to serve their time-sharing customers. It became operational in May 1976.
NPL
Donald DaviesDonald Davies
Donald Watts Davies, CBE FRS was a Welsh computer scientist who was one of the inventors of packet switching computer networking, and originator of the term.-Career history:...
of the National Physical Laboratory, UK
National Physical Laboratory, UK
The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, London, England. It is the largest applied physics organisation in the UK.-Description:...
made many important contributions to the theory of packet switching. NPL built a single node network to connect sundry hosts at NPL.
OCTOPUS
Octopus was a local network at Lawrence Livermore National LaboratoryLawrence Livermore National Laboratory
The Lawrence Livermore National Laboratory , just outside Livermore, California, is a Federally Funded Research and Development Center founded by the University of California in 1952...
. It connected sundry hosts at the lab to interactive terminals and various computer peripherals including a bulk storage system.
Philips Research
PhilipsPhilips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
Research Laboratories in Redhill, Surrey
Redhill, Surrey
Redhill is a town in the borough of Reigate and Banstead, Surrey, England and is part of the London commuter belt. Redhill and the adjacent town of Reigate form a single urban area.-History:...
developed a packet switching network for internal use. It was a datagram network with a single switching node.
PUP
The PARC Universal Packet (PUP or Pup) was one of the two earliest internetwork protocol suites; it was created by researchers at Xerox PARCXerox PARC
PARC , formerly Xerox PARC, is a research and co-development company in Palo Alto, California, with a distinguished reputation for its contributions to information technology and hardware systems....
in the mid-1970s. The entire suite provided routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...
and packet delivery, as well as higher level functions such as a reliable byte stream
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 were when the sender inserted them into the channel.The...
, along with numerous applications. Further developments led to Xerox Network Systems (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-circuitVirtual circuit
In telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
network in contrast to CYCLADES which was based on datagrams
Datagram
A datagram is a basic transfer unit associated with a packet-switched network in which the delivery, arrival time, and order are not guaranteed....
. 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 specification of X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
RETD
Red Especial de Transmisión de Datos 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 70's, and it included first Nordic electronic journal Extemplo. Libraries were also among first ones in universities to accommodate microcomputers for public use in early 80's."SITA HLN
SITASITA
SITA is a multinational information technology company specialising in providing IT and telecommunication services to the air transport industry...
is a consortium of airlines. Their High Level Network 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.
SNA
Systems Network ArchitectureSystems Network Architecture
Systems Network Architecture is IBM's proprietary networking architecture created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes the protocol and is, in itself, not actually a program...
(SNA) is IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
'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. This allowed construction of a private network.
Telenet
Telenet was the first FCC-licensed public data networkPublic Data Network
A public data network 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....
in the United States. It was founded by former ARPA IPTO director Larry Roberts as a means of making ARPANET technology public. He had tried to interest AT&T in buying the technology, but the monopoly's reaction was that this was incompatible with their future. Bolt, Beranack and Newman (BBN) provided the financing.
It initially used ARPANET technology but changed the host interface to X.25 and the terminal interface to X.29. Telenet designed these protocols and helped standardize them in the CCITT. Telenet was incorporated in 1973 and started operations in 1975. It went public in 1979 and was then sold to GTE.
Tymnet
Tymnet 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 async 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. (Interesting note: Tymnet was not named after Mr. Tyme. Another employee suggested the name.)XNS
Xerox Network Systems (XNS) was a protocol suite promulgated by XeroxXerox
Xerox Corporation is an American multinational document management corporation that produced and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies...
, which provided routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...
and packet delivery, as well as higher level functions such as a reliable stream, and remote procedure call
Remote procedure call
In computer science, a remote procedure call is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space without the programmer explicitly coding the details for this remote interaction...
s. It was developed from PARC Universal Packet
PARC Universal Packet
The PARC Universal Packet was one of the two earliest internetwork protocol suites; it was created by researchers at Xerox PARC in the mid-1970s...
(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 which was a joint venture of Bell CanadaBell Canada
Bell Canada is a major Canadian telecommunications company. Including its subsidiaries such as Bell Aliant, Northwestel, Télébec, and NorthernTel, it is the incumbent local exchange carrier for telephone and DSL Internet services in most of Canada east of Manitoba and in the northern territories,...
(a common carrier) and Northern Telecom (a telecommunications equipment supplier). Northern Telecom sold several DATAPAC clones to foreign PTTs including the Deutsche Bundespost
Deutsche Bundespost
The Deutsche Bundespost was created in 1947 as a successor to the Reichspost . Between 1947 and 1950 the enterprise was called Deutsche Post...
. X.75
X.75
X.75 is an International Telecommunication Union standard specifying the interface for interconnecting two X.25 networks. X.75 is almost identical to X.25...
and X.121
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 , connecting two network user addresses...
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
AUSTPACAUSTPAC
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 and remote terminal access to academic institutions, some of which...
was an Australian public X.25 network operated by Telstra
Telstra
Telstra Corporation Limited is an Australian telecommunications and media company, building and operating telecommunications networks and marketing voice, mobile, internet access and pay television products and services....
. Started by Telecom Australia
Telecom Australia
Telecom Australia was the trading name of the:* Australian Telecommunications Commission * Australian Telecommunications Corporation * Australian and Overseas Telecommunications Corporation...
in the early 1980s, AUSTPAC was Australia's first public packet-switched data network, supporting applications such as on-line betting, financial applications — the Australian Tax Office 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 can be via a dial-up terminal to a PAD
Packet Assembler/Disassembler
A packet assembler/disassembler, abbreviated PAD is a communications device which provides multiple asynchronous terminal connectivity to an X.25 network or host computer. It collects data from a group of terminals and places the data into X.25 packets...
, or, by linking a permanent X.25 node to the network.
ConnNet
ConnNetConnNet
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...
was a packet switched data network operated by the Southern New England Telephone Company serving the state of Connecticut.
Datanet 1
Datanet 1 was the public switched data network operated by the DutchNetherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
PTT Telecom (now known as KPN
KPN
KPN is a Dutch landline and mobile telecommunications company, including both 2G and 3G mobile operations...
). Strictly speaking Datanet 1 only referred to the network and the connected users via leased line
Leased line
A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...
s (using the X.121
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 , connecting two network user addresses...
DNIC 2041), the name also referred to the public PAD
Packet Assembler/Disassembler
A packet assembler/disassembler, abbreviated PAD is a communications device which provides multiple asynchronous terminal connectivity to an X.25 network or host computer. It collects data from a group of terminals and places the data into X.25 packets...
service Telepad (using the DNIC 2049). And because the main Videotex
Videotex
Videotex was one of the earliest implementations of an "end-user information system". From the late 1970s to mid-1980s, it was used to deliver information to a user in computer-like format, typically to be displayed on a television.In a strict definition, videotex refers to systems that provide...
service used the network and modified PAD
Packet Assembler/Disassembler
A packet assembler/disassembler, abbreviated PAD is a communications device which provides multiple asynchronous terminal connectivity to an X.25 network or host computer. It collects data from a group of terminals and places the data into X.25 packets...
devices as infrastructure
Infrastructure
Infrastructure is basic physical and organizational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function...
the name Datanet 1 was used for these services as well. Although this use of the name was incorrect all these services were managed by the same people within one department of KPN
KPN
KPN is a Dutch landline and mobile telecommunications company, including both 2G and 3G mobile operations...
contributed to the confusion.
Datapac
DATAPACDATAPAC
DATAPAC was Canada's packet switched X.25-equivalent data network. Operated first by Trans-Canada Telephone System, then Telecom Canada, then the Stentor Alliance, it finally reverted to Bell Canada when the Stentor Alliance was dissolved.-Use:...
was the first operational X.25 network (1976). It covered major Canadian cities and was eventually extended to smaller centres.
Datex-P
Deutsche Bundespost operated this national network in Germany. The technology was acquired from Northern Telecom.Eirpac
EirpacEirpac
EIRPAC is Ireland's packet switched X.25 data network. It replaced Euronet in 1984. Eirpac uses the DNIC 2724. HEAnet was first in operation via X.25 4.8Kb Eirpac connections back in 1985. By 1991 most Universities in Ireland used 64k Eirpac VPN connections...
is the Irish public switched data network supporting X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
and X.28
X.28
X.28 is an ITU-T standard specifying the interface between asynchronous character-mode data terminal equipment , such as computer terminals, and a Packet Assembler/Disassembler that connects the DTE to a packet switched network such as an X.25 network.-External links:*...
. It was launched in 1984, replacing Euronet. Eirpac is run by Eircom
Eircom
Eircom Group LTD is a telecommunications company in the Republic of Ireland, and a former state-owned incumbent. It is currently the largest telecommunications operator in the Republic of Ireland and operates primarily on the island of Ireland, with a point of presence in Great Britain.As Bord...
.
HIPA-NET
HitachiHitachi
Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family...
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 is the Spanish public packet switched network, providing X.25X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
services. Iberpac is run by Telefonica
Telefónica
Telefónica, S.A. is a Spanish broadband and telecommunications provider in Europe and Latin America. Operating globally, it is the third largest provider in the world...
.
JANET
JANETJANET
JANET is a private British government-funded computer network dedicated to education and research. All further- and higher-education organisations in the UK are connected to JANET, as are all the Research Councils; the majority of these sites are connected via 20 metropolitan area networks JANET...
was the UK academic and research network, linking all universities, higher education establishments, publicly funded research laboratories. The X.25 network was based mainly on GEC 4000 series
GEC 4000 series
The GEC 4000 was a series of 16/32-bit minicomputers produced by GEC Computers Ltd. of the UK during the 1970s, 1980s and early 1990s.- History :...
switches, and run X.25 links at up to 8 Mbit/s in its final phase before being converted to an IP based network. The JANET network grew out of the 1970s SRCnet (later called SERCnet) network.
PSS
PSSPacket Switch Stream
In the United Kingdom, Packet Switch Stream was an X.25-based packet-switched network, provided by the British Post Office Telecommunications and then British Telecom starting in 1980...
was the UK Post Office (later to become British Telecom) national X.25 network with a DNIC of 2342. British Telecom renamed PSS under its GNS (Global Network Service) name, 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.
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.Venepaq
Venepaq is the national X.25 public network in Venezuela. It is run by CantvCANTV
CANTV is one of the first telephone service enterprises in Venezuela, founded in 1930. The company was re-nationalized in 2007.As of May 9, 2008, Cantv’s customer base numbered 10.1 million mobile subscribers, 5.2 million fixed telephony subscribers and 1,000,000 broadband subscribers.- Origins...
and allow direct connection and dial up connections. Provides nationalwide access at very low cost. It provides national and international access. Venepaq allow conection from 19.2 Kbps to 64 Kbps in direct connections, and 1200, 2400 and 9600 bps in dial up connections. For more information, call (toll free) 0-800-EMPRESA (3677372) inside Venezuela from any land phone.
Internet era
When Internet connectivity was made available to anyone who could pay for an ISPInternet service provider
An Internet service provider is a company that provides access to the Internet. Access ISPs directly connect customers to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and host other people servers...
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
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
have resurfaced with new names such as fast packet switching
Fast packet switching
In telecommunications, fast packet switching is a packet switching technique that increases the throughput by eliminating overhead. Overhead reduction is accomplished by allocating flow control and error correction functions to either the user applications or the network nodes that interface with...
. Researchers have created some experimental networks to complement the existing Internet.
Internet2
Internet2 is not an actual network. It is a research consortium which has created the Abilene NetworkAbilene Network
Abilene Network was a high-performance backbone network created by the Internet2 community in the late 1990s. In 2007 the Abilene Network was retired and upgraded network was known as the "Internet2 Network".-History:...
.
National LambdaRail
National LambdaRail is a high-speed national computer network in the United States that runs over fiber-optic lines, and is the first transcontinental Ethernet network working to establish a direct line of communications between international parties.See also
- Public switched data networkPublic switched data networkA public switched data network is a publicly-available packet-switched network, distinct from the PSTN.Originally this term referred only to Packet Switch Stream , an X.25-based packet-switched network, mostly used to provide leased-line connections between local area networks and the Internet...
- Public data networkPublic Data NetworkA public data network 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....
- CompuserveCompuServeCompuServe was the first major commercial online service in the United States. It dominated the field during the 1980s and remained a major player through the mid-1990s, when it was sidelined by the rise of services such as AOL with monthly subscriptions rather than hourly rates...
- Virtual private networkVirtual private networkA virtual private network is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network....
- Virtual circuitVirtual circuitIn telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
External links
- "The Guide to Hacking & Phreaking, Issue #2", Liquid Jesus
- "Hobbes' Internet Timeline v8.1", Robert H'obbes' Zakon, Zakon Group LLC
- 20+ articles on packet switching in the 70s
- "An Introduction to Packet Switched Networks", Phrack, 05/3/88
- EPSS Pictures of the EPSS exchanges in London, Manchester and Glasgow.