What was the first computer network in the world?

The first computer network that appeared in the world was "ARPANET". ARPANET is the prototype of the world's first substantial computer Internet. It is the world's first operational packet switching network developed by the U.S. Defense Advanced Research Projects Agency. It is the ancestor of the global Internet.

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The first computer network that appeared in the world was "ARPANET".

ARPANET (ARPANET), the full name is "Defense Advanced Projects Agency Network". In October 1968, the US Department of Defense Advanced Projects Agency signed a contract with BBN Company to develop a network suitable for computer communications.

ARPANET was the world's first operating packet switching network developed by the U.S. Defense Advanced Research Projects Agency. It is the ancestor of the global Internet.

In October 1968, the U.S. Department of Defense Advanced Projects Agency signed a contract with BBN Company to develop a network suitable for computer communications. The first phase of work was completed in June 1969, and an experimental network of four nodes was formed, called ARPAnet. It is recognized as the world's first network built using packet switching technology. In the summer of 1975, ARPAnet ended its experimental phase, and network control was handed over to the U.S. Department of Defense Communications Agency (DCA). DCA established the U.S. Defense Data Network (DDN) based on ARPAnet.

Historical progress of ARPANET:

First phase

In November 1969, the U.S. Department of Defense Advanced Research Projects Administration (ARPA’s full name: Advanced Research Projects Agency) began to build a network named ARPAnet, but there were only four nodes, distributed at four universities in Los Angeles: UCLA, UC Santa Barbara, Stanford University, and the University of Utah of 4 mainframe computers. One factor in selecting these four nodes is the compatibility of different types of host networking. Of great significance to the development of arparnet is that it utilizes wireless packet switching networks and satellite communication networks. Several military and research computer hosts in the United States are connected to each other through specialized interface signal processors (IMP) and specialized communication lines. It was originally developed to facilitate the sharing of resources between these schools. ARPANET uses a packet switching mechanism. At the beginning, ARPAnet only connected four hosts. From a military requirement, it was under the protection of high-level secrets of the U.S. Department of Defense. Technically, it did not have the conditions for external promotion. Initially, ARPAnet was mainly used for military research purposes. It was mainly based on the guiding ideology that the network must withstand failures and maintain normal work. In the event of a war, when a certain part of the network loses the ability to work due to an attack During this time, other parts of the network should be able to maintain normal communication operations. Another major technical contribution of ARPAnet is the development and utilization of the TCP/IP protocol suite. As the early backbone network of the Internet, ARPAnet's experiments laid the foundation for the existence and development of the Internet, and better solved a series of theoretical and technical problems in heterogeneous machine network interconnection.

Second Phase

By 1975, arpanet had connected to more than 100 hosts, ended the network test phase, and was handed over to the Defense Communications Agency of the U.S. Department of Defense for official operation. On the basis of summarizing the practical experience of the first phase of network construction, the researchers began the design work of the second generation network protocol. The focus of this stage is on network interconnection issues. In-depth research on network interconnection technology has led to the emergence and development of the TCP/IP protocol (translated in Chinese as Transmission Control Protocol/Internet Interconnection Protocol). By 1979, more and more researchers were investing in the research and development of the tcp/IP protocol. Around 1980, all arpanet hosts switched to the TCP/IP protocol. By January 1983, the conversion of arpanet to tcp/ip was completed. At the same time, the Defense Communications Agency of the U.S. Department of Defense divided arpanet into two independent parts. One part is still called arpanet and is used for further research work; the other part is slightly larger and becomes the famous MILNET, which is used for the military's unclassified communications.

The third phase

In the 1970s, the protocol successfully expanded the size of data packets and formed the Internet.

In 1983, ARPA and the U.S. Department of Defense Communications Agency successfully developed the TCP/IP protocol for heterogeneous networks. The University of California, Berkeley, used the protocol as its BSD UNIX (a software program of the University of California, Berkeley). As part of the group's operating system, the protocol became popular in society, thus giving birth to the real Internet. That year, ARPAnet split into two parts, ARPAnet and the purely military MILNET. At the same time, the emergence and vigorous development of local area networks and wide area networks have played an important role in the further development of the Internet. The most eye-catching one is NSFnet established by the National Science Foundation (NSF). NSF established regional computer wide area networks throughout the United States and interconnected these regional networks with supercomputer centers. NSFnet completely replaced ARPAnet in June 1990 and became the backbone network of the Internet.

The fourth stage

In 1986, the National Science Foundation (NSF) used IP communications developed by ARPAnet to establish the NSFnet wide area network based on five supercomputer centers for scientific research and education services. Due to the encouragement and funding from the National Science Foundation, many universities, government-funded research institutions and even private research institutions have integrated their local area networks into NSFnet. At that time, the military part of ARPAnet had separated from the main network and established its own network-Milnet. ARPAnet, the father of the Internet, was gradually replaced by NSFnet. By 1990, ARPAnet had withdrawn from the stage of history. Today, NSFnet has become one of the important backbone networks of the Internet.

ARPA was renamed DARPA in 1971, so DARPANET is sometimes used to refer to ARPANET. The two words mean the same thing.

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