The TCP/IP model is the backbone of the internet and many other networks, but it was not always the dominant protocol suite. In this article, you will learn how the TCP/IP model evolved from the ARPANET project, a pioneering research network funded by the US Department of Defense in the 1960s and 1970s.
The Advanced Research Projects Agency Network (ARPANET) was the first large-scale packet-switching network, which means it transmitted data in small units called packets, rather than in continuous streams. Packet-switching allowed multiple computers to share the same communication lines, increasing efficiency and reliability. The ARPANET connected several universities and research centers across the US, and was designed to support military and scientific applications.
The evolution of the TCP/IP model from the ARPANET project was a pivotal moment in the development of the modern internet. ARPANET, initiated by DARPA in the late 1960s, was an innovative experiment connecting various computers and researchers. In the mid-1970s, Vinton Cerf and Bob Kahn introduced the groundbreaking Transmission Control Protocol (TCP) and Internet Protocol (IP). TCP ensured reliable data packet delivery, while IP facilitated data routing across networks. These protocols formed the basis of the TCP/IP model, which governs data transmission and routing. ARPANET's shift to TCP/IP marked the birth of the modern internet, connecting billions of users and devices globally.
The TCP/IP model emerged from the ARPANET project as a response to the growing complexity of network communication and the need for a more reliable and scalable protocol. In the 1970s, TCP was developed to provide reliable and error-checked data delivery, and IP was created to route data packets between nodes. TCP and IP formed the TCP/IP protocol suite, which became the standard for communication on the internet. The TCP/IP model consists of four layers: application, transport, internet, and network access.
ILECs thought they had it figured out. They were greedy, and didn't think about the implications of higher bandwidth. They wanted to own the last mile, and have everyone tie into their network at the Central Office, from the co-location areas to their Mainframe. There is still cabling waiting to be terminated in those Colo cages from 2000. They missed their opportunity, and are now mainly transport backbone. Sure they still get a slice, but I guarantee the data centers they now transport service for make a ton more. As soon as someone figured out they didn't need to co-locate inside the CO, and they could send a pipe of bandwidth to a different location, the game forever changed.
One of the main challenges faced by the ARPANET was how to make different types of computers and networks communicate with each other. Different systems used different protocols, or rules for data exchange, which were often incompatible. For example, some systems used 8-bit bytes, while others used 36-bit words. Some systems used variable-length packets, while others used fixed-length packets. To solve this problem, the ARPANET developed a set of standard protocols called the Network Control Program (NCP), which defined how packets were formatted, addressed, routed, and acknowledged.
However, the NCP was not flexible enough to accommodate the growing diversity and complexity of networks. In the early 1970s, a team of researchers led by Vinton Cerf and Robert Kahn proposed a new protocol suite called Transmission Control Protocol/Internet Protocol (TCP/IP), which separated the functions of packet-switching and end-to-end reliability. TCP/IP consisted of two main layers: the Internet Protocol (IP), which handled the routing and addressing of packets across networks, and the Transmission Control Protocol (TCP), which ensured the reliable delivery and reassembly of packets at the destination. TCP/IP also allowed for the creation of subprotocols for specific applications, such as email, file transfer, and remote login.
The TCP/IP protocol suite was tested and refined throughout the 1970s and 1980s, with the help of several experimental networks, such as the Packet Radio Network (PRNET), the Satellite Network (SATNET), and the Local Area Network (LAN). In 1983, the ARPANET officially switched from NCP to TCP/IP, marking the start of the modern internet. TCP/IP also became the standard protocol for other networks, such as the National Science Foundation Network (NSFNET), which connected academic and research institutions, and the Commercial Internet Exchange (CIX), which connected commercial service providers. TCP/IP enabled the interconnection of diverse and independent networks, creating a global network of networks.
The TCP/IP protocol suite has evolved over time to meet the changing needs and challenges of the internet. For example, the original IP version 4 (IPv4) had a limited address space of 32 bits, which could only support about 4 billion devices. To overcome this limitation, a new version of IP, called IPv6, was developed, which has a much larger address space of 128 bits, which can support about 340 undecillion devices. Another example is the development of new subprotocols for emerging applications, such as the Hypertext Transfer Protocol (HTTP), which enables the exchange of web pages, and the Secure Sockets Layer (SSL), which provides encryption and authentication for web transactions.
The TCP/IP protocol suite is one of the most influential and successful inventions in the history of computing and communication. It has enabled the creation and expansion of the internet, which has transformed every aspect of human society, from education and entertainment to business and politics. It has also fostered innovation and collaboration among researchers, developers, and users, who have contributed to the improvement and diversification of the TCP/IP protocol suite. The TCP/IP model is not only a technical achievement, but also a cultural and social phenomenon.