History of the Internet

History of the internet

Introduction

The Internet has revolutionized the computer and communications world like nothing before. The invention of the telegraph, telephone, radio, and computer set the stage for this unprecedented integration of capabilities. The Internet is a world-wide broadcasting capability, a mechanism for gathering information, and a medium for communication and interaction between individuals and their computers without regard for geographic location.

The Internet represents one of the most successful examples of the benefits of sustained investment and commitment to research and development of information infrastructure. Beginning with the early research in packet switching, the government, industry and academia have been partners in evolving and deploying this exciting new technology. Today, the average person commonly uses terms like 'mclennox@ilink.nis.za' and 'http://lennox.w3.to'.

The Internet today is a widespread information infrastructure, the initial prototype of what is often called the National Information Infrastructure. Its history is complex and its influence reaches not only to the technical fields of computer communications but throughout society as we move toward increasing use of online tools to accomplish electronic commerce, information acquisition, and community operations.

The Initial Internet Concepts

The original ARPANET grew into the Internet. Internet was based on the idea that there would be multiple independent networks, beginning with the ARPANET as the pioneering packet switching network, but soon to include packet satellite networks, ground-based packet radio networks and other networks. In this approach, the choice of any individual network technology was not dictated by a particular network architecture but rather could be selected freely by a provider and made to interwork with the other networks. Up until that time there was only one general method for federating networks. This was the traditional circuit switching method where networks would interconnect at the circuit level, passing individual bits on a synchronous basis along a portion of an end-to-end circuit between a pair of end locations. Kleinrock had shown in 1961 that packet switching was a more efficient switching method. Along with packet switching, special purpose interconnection arrangements between networks were another possibility. While there were other limited ways to interconnect different networks, they required that one be used as a component of the other.

In an open-architecture network, the individual networks may be separately designed and developed and each may have its own unique interface which it may offer to users and other Internet providers. Each network can be designed in accordance with the specific environment and user requirements of that network. There are generally no constraints on the types of network that can be included.

The idea of open-architecture networking was first introduced by Kahn shortly after having arrived at DARPA in 1972. This work was originally part of the packet radio program, but then became a separate program in its own right. At the time, the program was called 'Internetting'. Kahn first contemplated developing a protocol local only to the packet radio network, since that would avoid having to deal with the multitude of different operating systems, and continuing to use NCP.

However, NCP did not have the ability to address networks (and machines) further downstream than a destination IMP on the ARPANET and thus some change to NCP would also be required. (The assumption was that the ARPANET was not changeable in this regard). NCP relied on ARPANET to provide end-to-end reliability. If any packets were lost, the protocol would come to a halt.

Kahn decided to develop a new version of the protocol which could meet the needs of an open-architecture network environment. This protocol would eventually be called the Transmission Control Protocol/Internet Protocol (TCP/IP). While NCP tended to act like a device driver, the new protocol would be more like a communications protocol.

Four ground rules were critical to Kahn's early thinking:

* Each distinct network would have to stand on its own and no internal changes could be required to any such network to connect it to the Internet.

* Communications would be on a best effort basis. If a packet didn't make it to the final destination, it would shortly be retransmitted from the source.

* Black boxes would be used to connect the networks; these would later be called gateways and routers. There would be no information retained by the gateways about the individual flows of packets passing through them, thereby keeping them simple and avoiding complicated adaptation and recovery from various failure modes.

* There would be no global control at the operations level.

Other key issues that needed to be addressed were:

* Algorithms to prevent lost packets from permanently disabling communications and enabling them to be successfully retransmitted from the source.

* Providing for host to host "pipelining" so that multiple packets could be enroute from source to destination at the discretion of the participating hosts, if the intermediate networks allowed it.

* Gateway functions to allow it to forward packets appropriately. This included interpreting IP headers for routing, handling interfaces, breaking packets into smaller pieces if necessary, etc.

* The need for end-end checksums, reassembly of packets from fragments and detection of duplicates, if any.

* The need for global addressing

* Techniques for host to host flow control.

* Interfacing with the various operating systems

* There were also other concerns, such as implementation efficiency, internetwork performance, but these were secondary considerations at first.

Kahn began work on a communications-oriented set of operating system principles while at BBN and documented some of his early thoughts in an internal BBN memorandum entitled. At this point he realized it would be necessary to learn the implementation details of each operating system to have a chance to embed any new protocols in an efficient way. Thus, in the spring of 1973, after starting the internetting effort, he asked Vint Cerf to work with him on the detailed design of