ARPANET (Advanced Research Projects Agency Network) was the first wide-area packet-switching network with distributed control and one of the first networks to implement the protocol suite TCP/IP. Both of these features were seminal in the establishment of today’s global Internet.
The Inception and Early Days of ARPANET
The idea of ARPANET was first articulated by its creators in a series of memos written by Robert Taylor of the Information Processing Techniques Office (IPTO) at ARPA (Advanced Research Projects Agency), a branch of the U.S. Department of Defense, in 1966. The project was aimed at utilizing idle computer resources across research institutions by connecting them through a network.
The first functional ARPANET link was established on November 21, 1969, between the University of California, Los Angeles (UCLA) and the Stanford Research Institute (SRI). By the end of 1971, 15 sites, consisting of university research departments and military installations, were connected to the ARPANET network.
Delving into the Details of ARPANET
The backbone of ARPANET’s design was packet switching, a revolutionary networking technique at the time. Before packet switching, data transmission between computers used circuit-switching, which was like a dedicated phone line, maintained for the duration of the transmission. Packet switching, on the other hand, divided the data into small pieces or packets, which could then follow the most efficient route through the network before being reassembled at their destination.
ARPANET was also among the first networks to implement the TCP/IP protocol suite, which became the standard for all Internet connectivity. TCP/IP was designed and implemented by Vint Cerf and Bob Kahn in 1973, and ARPANET adopted it on January 1, 1983.
The Architecture and Functioning of ARPANET
The internal structure of ARPANET comprised packet-switching nodes known as Interface Message Processors (IMPs). Each IMP was a Honeywell DDP-516 minicomputer paired with specialized communications hardware. The IMPs were interconnected by high-speed lines. Each IMP could support up to six hosts, and communications between hosts were achieved through packet switching.
The hosts could be mainframes, minicomputers, workstations, and the like, each running network software for the chosen protocol suite. The protocols were implemented in a hierarchical manner. At the lower level, the network interface protocols governed the interaction between the host computer and the IMP to which it was attached. At the higher level, host-to-host protocols enabled the exchange of data among the hosts.
Key Features and Contributions of ARPANET
ARPANET’s key features included:
-
Packet-switching technology: This was a major shift from the traditional circuit-switching systems and is now the de-facto standard in modern Internet communications.
-
TCP/IP protocol suite: ARPANET was among the first networks to implement TCP/IP, which is now the foundation of the Internet.
-
Distributed control: Unlike other systems of the time, control was not centralized in ARPANET. This feature contributed to the robustness and resilience of the network.
-
Use of Interface Message Processors (IMPs): The use of IMPs was a precursor to the modern concept of routers.
Variations of ARPANET
Over time, several related networks evolved from ARPANET, which shared many of its key features. Here are some of them:
| Network | Description |
|---|---|
| MILNET | A network split off from ARPANET in 1983 to provide a dedicated network for the U.S. military. |
| CSNET | The Computer Science Network was established in 1981 to provide networking services to university computer scientists. |
| NSFNET | The National Science Foundation Network was a program initiated in 1985 to promote advanced research and education networking in the United States. |
Usage, Issues and Solutions
ARPANET was primarily used for open research and communication among the connected institutions. It facilitated the sharing of super-computers amongst researchers, and became a high-speed digital post office for sending electronic mail, the first application of the internet.
However, ARPANET faced several challenges, including a lack of a universally agreed-upon set of protocols and a paucity of networked applications. These were addressed through the adoption of TCP/IP as the universal protocol suite and the development of various applications such as electronic mail, file transfer, and remote login.
Comparative Analysis with Similar Networks
While ARPANET was the precursor to the modern internet, other networks also contributed to the internet as we know it. Here is a comparative table:
| Network | Key Contributions |
|---|---|
| ARPANET | Developed and implemented concepts of packet switching, and TCP/IP protocols. |
| NPL Network | Demonstrated the feasibility of packet switching. |
| Merit Network | Developed network technologies and influenced standards. |
| CYCLADES | Developed the concept of the datagram and influenced TCP/IP. |
While ARPANET was officially decommissioned in 1990, its core technologies continue to drive internet development. Technologies that can trace their lineage back to ARPANET include cloud computing, VPNs, and large-scale networks such as the Internet of Things (IoT).
ARPANET and Proxy Servers
While ARPANET itself didn’t use proxy servers, these servers have become an integral part of the modern internet, which grew out of ARPANET. Proxy servers act as intermediaries in the flow of internet traffic, helping improve service security, performance, and privacy – features that continue to echo the distributed, robust nature of ARPANET.
Related Links
For those who wish to explore further, here are a few links to additional resources:
-
The ARPANET Completion Report – A detailed summary of ARPANET from its inception to decommissioning.
-
Internet History – A comprehensive history of the internet, including ARPANET’s role.
-
The Computer History Museum – An extensive collection of artifacts and information about the history of computing, including the development of ARPANET.
