You might have heard about ARPANet being called the "first internet." That‘s true in some ways – ARPANet pioneered concepts and technologies that would later evolve into today‘s internet. As the first wide area computer network, ARPANet connected multiple research institutions across distances starting in 1969.
In this comprehensive guide, I‘ll walk you through ARPANet‘s foundations and inner workings. You‘ll learn about the people and innovations in networking, hardware, and software that allowed this leap in data transmission capabilities at the time. I‘ll also analyze ARPANet‘s usage and influence, shedding light on why it proved so essential for the internet‘s later growth.
Overview: What was ARPANet For?
ARPA or the Advanced Research Projects Agency (now called DARPA) funded ARPANet with the goal of connecting computers at various research sites through a resilient, adaptable network for communication and resource sharing purposes.
At a time when most computer systems ran independently, ARPANet allowed joined-up infrastructure. For example, scientists in California could access research databases or expensive computing resources housed at facilities in Utah or Boston through remote data transmission on ARPANet.
Beyond that, ARPANet created possibilities for collaborative, interactive computing applications across a long distance in real-time. This was considered groundbreaking in the late 1960s setting when most analog phone lines only facilitated one-to-one connections.
The Network Takes Shape (1967 – 1969)
In 1967, ARPA computer science manager Larry Roberts spearheaded the ARPANet project to make this interconnected system a reality. By 1969, Roberts and his team had implemented the first 4-node ARPANet linking computers at UCLA, Stanford Research Institute, UC Santa Barbara, and the University of Utah using 50kbps lines.
This marked the first realization of wide area computer networking – a monumental moment that changed the possibilities of computing forever. By 1971, an additional 15 nodes spanning various academic and research institutions got added, with ARPANet proving robust and adaptable right from the start.
Key Innovations Powering ARPANet
Let‘s go over some of the major technical achievements behind ARPANet‘s functioning as the pioneering computer network.
Interface Message Processors
The team designed special Interface Message Processors (IMPs) to handle routing, flow control, error checking, and packet switching. Built by defense contractor BBN, these dedicated "post offices" became the backbone for relaying data on ARPANet reliably between various host computers.
Robust Packet Switching
IMPs implemented packet switching methodology formulated by Leonard Kleinrock and Paul Baran in the 60s. Messages got split into formatted chunks called packets, each traveling independently towards the destination where they got recompiled in order. This conferred major advantages – if any node failed on ARPANet or lines congested, packets took alternate paths dynamically, giving the network great resilience.
By 1974, ARPANet could relay about 75,000 packets each day between roughly 20 hosts!
Communication Protocols
In the early 1970s, researchers developed communication rules called protocols defining how two networked entities would transfer packets reliably. Known as Network Control Protocol (NCP), it became the standard way hosts on ARPANet talked to each other logically.
By 1983, NCP got replaced by the TCP/IP model designed by Kahn/Cerf – the universal internetworking model we still use extensively today!
Life on ARPANet: Applications Come Online
With ARPANet operational by 69, developers worked on innovative applications leveraging real-time data links. This spawned email in 71 (Tomlinson‘s SNDMSG), remote computer access (Telenet), and file transfers (FTP) by 73 – shaping how we network today!
By 75, mailing lists, chat applications, and an early form of instant messaging called MSG came about. The possibilities must have been astonishing for researchers at the diverse connected institutions. Imagine sitting at UCLA being able access research documents all the way from MIT‘s databases!
ARPANet to Internet: Setting the Stage
Throughout the 70s, ARPANet kept expanding, incorporating international nodes by 73. But by the early 80s, managing a single monolithic network became complex. ARPA adopted a flexible layered model allowing interconnected networks to communicate via common protocols (like TCP/IP).
This paved the way for the "internet" we know – a network of networks! With strong tenets and usage experience established by ARPANet, many networks (like CSNET, BITNET, NSFNet) arose adopting these standard ways to exchange information, together forming today‘s rich internet ecosystem.
So while the current internet has grown far more complex since then, remember – all of it owes its existence to the pioneering ARPANet backbone laid out in the late 60s!
I hope you enjoyed this comprehensive overview tracing ARPANet‘s origins, workings, applications and influence. Let me know if you have any other questions!
