Internet (ARPA NET in early times)

The Internet, Then known as ARPANET, was brought online in 1969 under a contract let by the renamed Advanced Research Projects Agency (ARPA) which initially connected four major computers at universities in the southwestern US. The contract was carried out by BBN of Cambridge,MA under Bob Kahn and went online in December 1969.

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.

The history of the Internet began with the development of electronic computers in the 1950s. The public was first introduced to the concepts that would lead to the Internet when a message was sent over the ARPANet from computer science Professor Leonard Kleinrock's laboratory at University of California, Los Angeles (UCLA), after the second piece of network equipment was installed at Stanford Research Institute (SRI). Packet switched networks such as ARPANET, Mark I at NPL in the UK, CYCLADES, Merit Network, Tymnet, and Telenet, were developed in the late 1960s and early 1970s using a variety of protocols. The ARPANET in particular led to the development of protocols for internetworking, in which multiple separate networks could be joined together into a network of networks.

In 1982, the Internet protocol suite (TCP/IP) was standardized, and consequently, the concept of a world-wide network of interconnected TCP/IP networks, called the Internet, was introduced. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) developed the Computer Science Network (CSNET) and again in 1986 when NSFNET provided access to supercomputer sites in the United States from research and education organizations. Commercial Internet (ISPs) began to emerge in the late 1980s and early 1990s. The ARPANET was decommissioned in 1990. The Internet was commercialized in 1995 when NSFNET was decommissioned, removing the last restrictions on the use of the Internet to carry commercial traffic.

Promoted to the head of the information processing office at DARPA, Robert Taylor intended to realize Licklider's ideas of an interconnected networking system. Bringing in Larry Roberts from MIT, he initiated a project to build such a network. The first ARPANET link was established between the University of California, Los Angeles (UCLA) and the Stanford Research Institute at 22:30 hours on October 29, 1969.

"We set up a telephone connection between us and the guys at SRI ...", Kleinrock ... said in an interview: "We typed the L and we asked on the phone,

"Do you see the L?"

"Yes, we see the L," came the response.

We typed the O, and we asked, "Do you see the O."

"Yes, we see the O."

Then we typed the G, and the system crashed ...

Yet a revolution had begun" ....