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The Packet Radio Network (PRNET) was a set of early, experimental mobile ad hoc networks whose technologies evolved over time. It was funded by the Advanced Research Projects Agency (ARPA). Major participants in the project included BBN Technologies, Hazeltine Corporation, Rockwell International's Collins division, and SRI International.
ARPA initiated the PRNET project in 1973, funding both theoretical and experimental research. Its goals were outlined in a 1975 paper by Bob Kahn, namely, to investigate the feasibility of using packet-switched, store-and-forward radio communications to provide reliable computer communications in a mobile environment. The earlier ALOHAnet served as an inspiration, but PRNET tackled a significantly harder set of problems, namely, multi-hop communications between mobile vehicles without a central station. In Kahn's initial conception, the overall system design was "predicated upon the existence of an array of low cost repeaters", where he defines the term to mean "a particular kind of packet radio which is equipped to retransmit by radio some or all packets which it receives by radio". In today's terminology, this might be called a router or a packet switch, rather than a radio repeater.
The first PRNET was established under the auspices of SRI in the San Francisco Bay Area, with BBN contributing network technology and Collins creating the Experimental Packet Radios (EPRs), which implemented L-band spread-spectrum waveforms and supported half-duplex communications at 100 or 400 kilobits/second. There was also a smaller network at BBN, for software development and testing. The first packet radios were delivered in mid-1975 for initial testing and a quasi-operational network capability was established for the first time in September 1976, shortly after the prototype networking software was developed. By 1977, this software included radio network routing control; a gateway to other networks; network measurement; debugging tools; and configuration tools.
PRNET was sufficiently advanced by 1977 to participate in the initial three-way internetworking demonstration, which linked a mobile vehicle in PRNET with nodes in the ARPANET, and via SATNET, to nodes in London. Afterwards, it was usually attached to the ARPANET so that BBN software developers could access and update it from Cambridge. By June 1978, about 25 radio nodes were available.
By September 1979, "Ron [Kunzelman] reported that SRI is now operating two PRNETs in the San Francisco bay area, and one PRNET at Ft. Bragg, North Carolina. The net at Ft. Bragg is now eight terminals on two TIUs, and will grow to forty terminals."
The Experimental Packet Radios were later replaced by Upgraded Packet Radios (UPR), circa 1978, and in 1986 by Low-Cost Packet Radio (LPR) as part of DARPA's follow-on SURAN project.
The history of the Internet has its origin in the efforts to build and interconnect computer networks that arose from research and development in the United States and involved international collaboration, particularly with researchers in the United Kingdom and France.
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 interconnected networks are called an internetwork, or simply an internet.
The Internet Protocol (IP) is the principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.
The Internet protocol suite is the conceptual model and set of communications protocols used in the Internet and similar computer networks. It is commonly known as TCP/IP because the foundational protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP). During its development, versions of it were known as the Department of Defense (DoD) model because the development of the networking method was funded by the United States Department of Defense through DARPA. Its implementation is a protocol stack.
Packet radio is a digital radio communications mode used to send packets of data. Packet radio uses packet switching to transmit datagrams. This is very similar to how packets of data are transferred between nodes on the Internet. Packet radio can be used to transmit data long distances.
In telecommunications, packet switching is a method of grouping data that is transmitted over a digital network into packets. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by application software. Packet switching is the primary basis for data communications in computer networks worldwide.
The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, application-specific features reside in the communicating end nodes of the network, rather than in intermediary nodes, such as gateways and routers, that exist to establish the network.
BBN Technologies was an American research and development company, based next to Fresh Pond in Cambridge, Massachusetts, United States.
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switching network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the Advanced Research Projects Agency (ARPA) of the United States Department of Defense.
Robert Elliot Kahn 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 heart of the Internet.
The Interface Message Processor (IMP) was the packet switching node used to interconnect participant networks to the ARPANET from the late 1960s to 1989. It was the first generation of gateways, which are known today as routers. An IMP was a ruggedized Honeywell DDP-516 minicomputer with special-purpose interfaces and software. In later years the IMPs were made from the non-ruggedized Honeywell 316 which could handle two-thirds of the communication traffic at approximately one-half the cost. An IMP requires the connection to a host computer via a special bit-serial interface, defined in BBN Report 1822. The IMP software and the ARPA network communications protocol running on the IMPs was discussed in, the first of a series of standardization documents published by the Internet Engineering Task Force (IETF).
Lawrence Gilman Roberts was an American engineer who received the Draper Prize in 2001 "for the development of the Internet", and the Principe de Asturias Award in 2002.
Peter Thomas Kirstein was a British computer scientist who played a role in the creation of the Internet. He put the first computer on the ARPANET outside of the US and was instrumental in defining and implementing TCP/IP alongside Vint Cerf and Bob Kahn. He is "often recognized as the father of the European Internet".
Virgil Donald Cone was a technician and later researcher at SRI International who developed and ran the Packet Radio Van that was used in the first ARPANET internetworked transmission.
The Packet Radio Van was a van refitted by Don Cone at SRI International, and equipped with technology that was used in the first two-way internetworked transmission on August 27, 1976, and the first three-way internetworked transmission on November 22, 1977; the latter of which is considered the start of the Internet.
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.
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.
The ARPANET pioneered the creation of novel encryption devices for packet networks in the 1970s and 1980s, and as such were ancestors to today's IPsec architecture, and High Assurance Internet Protocol Encryptor (HAIPE) devices more specifically.
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 robust computer networks. This culminated in the Internet–OSI Standards War in the late 1980s and early 1990s.