About 20 years ago the US Department of Defense created a network that became the predecessor of the Internet. It was called the ARPAnet The ARPAnet was an experimental network. It was created to support defense industry research, specifically methods of building networks resistant to partial damage from air bombardment and capable of continuing to function in such conditions. This requirement provides the key to understanding the principles of the Internet structure. The ARPAnet model always had a connection between a source computer and a receiving computer (point of destination). The network was a priori designed as unreliable: any part of the network could disappear at any moment.

The connected computers, not just the network alone, were also tasked with establishing and maintaining communication. The core principle was that any computer could connect with any other computer on a peer-to-peer basis.

Data traffic in the network was organized based on the Internet protocol – IP. The IP protocol is all about rules and descriptions of network operation. This set of rules includes rules for establishing and maintaining communication in the network, the rules of handling and processing IP packets, description of network packets of the IP family (their structure and so forth). The network was conceived and designed in such a way as not to require users to provide any information about specific network structure. To transmit a message via the network, a computer had to place data into a kind of “envelope” called IP, for example, specify a network address on this “envelope” and transfer the resulting packages into the network.

These solutions may seem strange, much lick the concept of an “unreliable” network. Yet existing experience has shown that most of these solutions are quite reasonable and correct. While the Organization for International Standardization (ISO) spent years creating a final standard for computer networks, the users did not want to wait. Internet activists started to install IP software on all possible types of computers. Soon this became the only acceptable way of communication between different computers. The government and universities, which had a policy of buying computers from different vendors, liked this model. Each of them bought a computer they wanted, and everybody expected their computer to be able to work jointly with other computers.