ARPANET, short for Advanced Research Projects Agency Network, was the pioneering project that laid the groundwork for the modern Internet. Initiated by the United States Department of Defense’s ARPA (Advanced Research Projects Agency) in 1966 and operational by 1969, ARPANET was designed to facilitate communication and resource sharing among government researchers and academic institutions.
History of ARPANET
During the Cold War, the United States Department of Defense’s Advanced Research Projects Agency (ARPA) began development of ARPANET as a means of creating a robust, decentralized communication network that could withstand potential disruptions, such as those from natural disasters or military attacks. The project began as a collaboration among several institutions, including the University of California, Los Angeles (UCLA), Stanford Research Institute (SRI), the University of California, Santa Barbara (UCSB), and the University of Utah.
The first message sent on ARPANET was on October 29, 1969, between UCLA and Stanford Research Institute (SRI). The intended message was “LOGIN,” but only “LO” was transmitted before the system crashed.
By 1971, ARPANET connected 15 nodes, including universities and research centers. It was during this decade that ARPANET expanded to include dozens of nodes across various research institutions and government agencies, facilitating unprecedented levels of collaboration and information sharing.
ARPANET facilitated innovations such as email, which became the first “killer app” of the network, drastically improving communication among researchers. The network expanded rapidly, leading to the development of protocols like TCP/IP (Transmission Control Protocol/Internet Protocol), which standardized communication across diverse networks and eventually became the foundation of the modern Internet.
By the late 1980s, the National Science Foundation Network (NSFNET) became the primary network backbone, allowing ARPANET to be decommissioned in 1989. The groundwork laid by ARPANET’s technologies and protocols directly contributed to developing the Internet as we know it today.
How did ARPANET work?
ARPANET’s development aimed to connect various research computers, enabling them to share information and computational resources.
Unlike traditional circuit-switching methods, ARPANET used packet switching. Pioneered by Paul Baran at RAND Corporation and Donald Davies at the National Physical Laboratory in the UK, packet switching became a fundamental concept in networking.
Packet switching breaks data into small packets that travel independently over the network before being reassembled at the destination Each packet contained not only a portion of the data but also addressing information, allowing it to find the most efficient path to its destination. This method significantly optimized network resource usage and improved resilience, as packets could be rerouted around damaged or congested areas of the network.
ARPANET and internet protocols
Even today, there are still Internet protocols being used that were first developed for ARPANET. In its early days, ARPANET utilized the Network Control Protocol (NCP) to manage communication between host computers. This protocol facilitated the transmission of data across the network by establishing a set of standards for data exchange. As the network expanded and interconnectivity between diverse systems became a necessity, the limitations of NCP became apparent, highlighting the need for more versatile and scalable solutions.
Researchers and engineers began developing the Transmission Control Protocol (TCP) and Internet Protocol (IP) during the mid-1970s. TCP was designed to handle reliable data transmission, including error detection, data segmentation, and flow control, ensuring that data packets reached their intended destinations accurately and in order. IP, meanwhile, provided the necessary mechanisms for addressing and routing packets across different networks. This separation of concerns allowed for greater flexibility and scalability. By the early 1980s, TCP/IP had become the de facto standard for network communication.
What is the legacy of ARPANET?
ARPANET demonstrated the feasibility of wide-area networking, and introduced essential protocols like TCP/IP, some of which are still in use today. Ultimately, ARPANET established the framework upon which the global Internet was built. For IT teams, understanding ARPANET is vital as it helps professionals better understand the networking concepts and technologies that underpin contemporary infrastructure.
