Table of Contents
ARPANET
The ARPANET was the first operational packet-switching network and the precursor to the modern internet. It was developed in the late 1960s under the direction of the Advanced Research Projects Agency (ARPA) of the United States Department of Defense. The goal of ARPANET was to create a decentralized network that would allow multiple research institutions to share resources and communicate efficiently. The network's design was based on the concept of packet switching, which was revolutionary at the time and enabled data to be sent in small units, or packets, across a distributed network of computers. The related RFC is RFC 1, which introduced the initial ideas for ARPANET host software and the concept of network communication through a collaborative, open process. https://en.wikipedia.org/wiki/ARPANET https://tools.ietf.org/html/rfc1
One of the key innovations of the ARPANET was the use of Interface Message Processors (IMPs), which acted as the routers of the network. IMPs were responsible for managing the transmission of data packets between the host computers connected to the network. The design of IMPs allowed the network to be fault-tolerant, meaning that if one part of the network failed, the data could still be routed through alternative paths. This resilience was one of the core motivations for developing the ARPANET, as it was seen as a way to maintain communication in the event of a military or infrastructure attack. The related RFC is RFC 2, which elaborates on how host software should interact with the IMPs for effective communication. https://en.wikipedia.org/wiki/Interface_Message_Processor https://tools.ietf.org/html/rfc2
Packet switching, the underlying technology of the ARPANET, represented a significant departure from traditional circuit-switching systems used in telecommunication networks. In circuit switching, a dedicated communication path is established between two parties for the duration of a transmission. In contrast, packet switching breaks data into small packets that are transmitted independently through the network and reassembled at the destination. This method of communication was more efficient and scalable, allowing multiple devices to share the same network infrastructure. The related RFC is RFC 791, which defines the Internet Protocol (IP) that later evolved from the packet-switching principles first used in the ARPANET. https://en.wikipedia.org/wiki/Packet_switching https://tools.ietf.org/html/rfc791
The ARPANET initially connected four nodes: University of California, Los Angeles (UCLA), Stanford Research Institute (SRI), University of California, Santa Barbara (UCSB), and the University of Utah. The first message sent over the ARPANET was transmitted from UCLA to SRI on October 29, 1969. Although the message was intended to be the word “LOGIN,” only the letters “L” and “O” were successfully sent before the system crashed. This marked the beginning of a revolutionary development in communications technology. The related RFC is RFC 1122, which discusses the requirements for internet hosts and the early developments in host communication that began with the ARPANET. https://en.wikipedia.org/wiki/History_of_the_Internet https://tools.ietf.org/html/rfc1122
The success of the ARPANET laid the foundation for the development of modern networking protocols. As more institutions joined the network, the need for standardized protocols to govern communication became apparent. This led to the development of the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which became the core protocols of the modern internet. The shift from ARPANET protocols to TCP/IP occurred in 1983, marking the transition from a research-focused network to the public internet that we know today. The related RFC is RFC 793, which defines TCP and its role in reliable communication across packet-switched networks. https://en.wikipedia.org/wiki/Transmission_Control_Protocol https://tools.ietf.org/html/rfc793
In the early years of the ARPANET, researchers developed the concept of Request for Comments (RFC) as a way to propose and discuss the development of network protocols and software. RFCs were intended to be informal documents that invited feedback and collaboration. The first RFC, RFC 1, was written by Steve Crocker in 1969 and laid the foundation for an iterative and open process for creating internet standards. The RFC series continues to this day and serves as the primary mechanism for proposing and formalizing internet protocols. The related RFC is RFC 2026, which outlines the process for creating internet standards through the RFC series. https://en.wikipedia.org/wiki/Request_for_Comments https://tools.ietf.org/html/rfc2026
As the ARPANET grew, it became clear that new protocols were needed to support a wider range of network services. One of the first major applications developed for the ARPANET was email. In 1971, Ray Tomlinson created the first email program, which allowed messages to be sent between users on different computers connected to the ARPANET. This innovation quickly became one of the most popular uses of the network and remains a critical application on the modern internet. The related RFC is RFC 5321, which defines the Simple Mail Transfer Protocol (SMTP) used for email transmission today. https://en.wikipedia.org/wiki/Email https://tools.ietf.org/html/rfc5321
The ARPANET also played a significant role in the development of the Domain Name System (DNS), which was created to map human-readable domain names to IP addresses. As the network expanded, it became increasingly difficult to manage hostnames manually, leading to the development of a hierarchical naming system. DNS was introduced in the early 1980s to automate the process of resolving domain names into IP addresses, a function that is now essential for navigating the internet. The related RFC is RFC 1035, which outlines the structure of DNS and its role in internet communication. https://en.wikipedia.org/wiki/Domain_Name_System https://tools.ietf.org/html/rfc1035
During its operation, the ARPANET became a testbed for many important networking concepts, including distributed computing and file-sharing protocols. The File Transfer Protocol (FTP), developed in the early 1970s, allowed users to transfer files between hosts on the network, paving the way for modern file-sharing and cloud storage services. FTP was one of the first protocols to be implemented on the ARPANET, and it remains in use today for specific applications. The related RFC is RFC 959, which defines the File Transfer Protocol and its role in networked file sharing. https://en.wikipedia.org/wiki/File_Transfer_Protocol https://tools.ietf.org/html/rfc959
The ARPANET was officially decommissioned in 1990, as the public internet had by then fully replaced it. However, the ARPANET's legacy lives on in the fundamental technologies and protocols that form the backbone of today's internet. Many of the key ideas developed for the ARPANET, such as packet switching, error control, and distributed computing, remain central to modern networking. The transition from the ARPANET to the internet also marked the beginning of the commercialization of the network, as private companies and individuals began to adopt and expand the infrastructure. The related RFC is RFC 1180, which provides a guide to understanding the TCP/IP protocols that evolved from the early ARPANET technologies. https://en.wikipedia.org/wiki/Decommissioning_of_the_Arpanet https://tools.ietf.org/html/rfc1180
As the first wide-area network to implement packet switching and to connect multiple institutions, the ARPANET was a pivotal moment in the history of computing and communications. It demonstrated that networks could scale to accommodate many different types of devices and services, and it set the stage for the explosive growth of the internet in the following decades. The open and collaborative nature of its development also set a precedent for the way that internet standards are developed through organizations like the Internet Engineering Task Force (IETF). The related RFC is RFC 1122, which outlines the requirements for internet hosts and their role in the global networking ecosystem. https://en.wikipedia.org/wiki/Internet_Engineering_Task_Force https://tools.ietf.org/html/rfc1122
Conclusion
The title of this RFC is “Host Software.” The ARPANET was the first operational packet-switching network and laid the groundwork for the modern internet. Through innovations like packet switching, distributed computing, and the development of early protocols like TCP, IP, and DNS, the ARPANET established many of the core principles that continue to shape the structure of the internet today. The collaborative development process initiated through the RFC series, starting with RFC 1, fostered the open and iterative approach to creating internet standards, which remains a defining feature of how the internet evolves. The transition from the ARPANET to the internet marks a key milestone in the history of global communication and connectivity.
- Snippet from Wikipedia: ARPANET
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first computer 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 (now DARPA) of the United States Department of Defense.
Building on the ideas of J. C. R. Licklider, Bob Taylor initiated the ARPANET project in 1966 to enable resource sharing between remote computers. Taylor appointed Larry Roberts as program manager. Roberts made the key decisions about the request for proposal to build the network. He incorporated Donald Davies' concepts and designs for packet switching, and sought input from Paul Baran on dynamic routing. In 1969, ARPA awarded the contract to build the Interface Message Processors (IMPs) for the network to Bolt Beranek & Newman (BBN). The design was led by Bob Kahn who developed the first protocol for the network. Roberts engaged Leonard Kleinrock at UCLA to develop mathematical methods for analyzing the packet network technology.
The first computers were connected in 1969 and the Network Control Protocol was implemented in 1970, development of which was led by Steve Crocker at UCLA and other graduate students, including Jon Postel and others. The network was declared operational in 1971. Further software development enabled remote login and file transfer, which was used to provide an early form of email. The network expanded rapidly and operational control passed to the Defense Communications Agency in 1975.
Bob Kahn moved to DARPA and, together with Vint Cerf at Stanford University, formulated the Transmission Control Program for internetworking. As this work progressed, a protocol was developed by which multiple separate networks could be joined into a network of networks; this incorporated concepts pioneered in the French CYCLADES project directed by Louis Pouzin. Version 4 of TCP/IP was installed in the ARPANET for production use in January 1983 after the Department of Defense made it standard for all military computer networking.
Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). In the early 1980s, the NSF funded the establishment of national supercomputing centers at several universities and provided network access and network interconnectivity with the NSFNET project in 1986. The ARPANET was formally decommissioned in 1990, after partnerships with the telecommunication and computer industry had assured private sector expansion and commercialization of an expanded worldwide network, known as the Internet.