What is the origin of the Internet and its basic ideas?
In 1961, three telephone relay bases were destroyed by terrorism in Utah, USA. The military line was temporarily shut down completely by this incident. The US Department of Defense considered that the conventional telephone network would be completely useless during the nuclear war, and began researching new communication systems.Subsequent research led to the creation of a network with the goal of achieving the two basic concepts of the current Internet.
2. Information packetization (parcel)
Now question is what is Distributed Network?
When communicating between (A) and (B) in the right figure, it is possible to communicate with (B) through the relay points of (A) to (C) in the figure. However, if the relay point (C) fails due to some trouble, communication between (A) and (B) will not be possible.
Therefore, not only the relay point of (C) but also the relay point of (D) can be used (the bottom of the figure). Even if (C) fails, bypassing (D) enables communication between (A) and (B). A network mechanism that does not depend on one place like this is called a distributed network.
What is Information Packetization (parcel)?
When communicating, sending data in small parts is called packetizing. By sending data in small portions, it is possible to send subsequent data even if communication is temporarily interrupted
Actual Operation & Subsequent Flow from Academic to Commercial Use
In September 1969, three universities in the United States were joined in September, and another university was added in December, and a 24-hour open network began to operate. The network was named "ARPAnet", following ARPA (US Department of Defense Advanced Research Projects Agency), which was directing the construction.
In the 1970s, there were several similar networks at universities and laboratories in the United States that did not participate in ARPAnet. After that, it expanded as an academic network in the 1980s, and by 1990, networks throughout the United States were interconnected.
The non-academic Internet, that is, the commercial Internet, started to be able to exchange e-mail between the Internet and PC communication in 1989, and in 1990, it could be a commercial access provider, and private use of the Internet was possible. On the other hand, in Japan, it was used as an academic network in some universities and research institutes in the 1980s. Commercial use was approved by the Ministry of Posts and Telecommunications in 1993 and has been put into operation.
In 1993, the website browsing software browser "Mozaic" was developed, and the Internet population exploded. The homepage itself has been used since 1991, but only character data has been used. Mozaic is the basis of browsers commonly used nowadays. After this, the price of personal computers themselves decreased, the cost of Internet connection decreased, and software progressed, and it became common to use the Internet not only at companies but also at homes.
Connection to the Internet from Home:-
In order to connect to the Internet, it is necessary to connect a line with a company that provides an Internet connection called an ISP (Internet Service Provider). As the type of connection line like telephone line, CATV line and optical fiber line etc. are generally used. Necessary devices other than PC vary depending on each line.
Telephone Connection
Connections using telephone lines have been made since the dawn of the Internet, and can be broadly divided into three types of connection methods: "general (analog) line", "ISDN line" and "ADSL line". Strictly speaking, "ADSL line" is an "analog line", but the form of contact and data transfer rate are different, so they are treated as different ones.
1. General (analog) Connection (necessary equipment: modem)
Connect to the provider through a modem. Connect the PC and the modem using a telephone line. Modems are also called "analog modems" to distinguish them from "cable modems" and "ADSL modems" used in other connection configurations.
Many PCs currently sold have analog modems built-in. However, the spread of ADSL will eliminate the need for analog modems and may reduce the number of embedded PCs. The characteristic of this connection is that since the connection is made by making a call to the provider through a modem, the telephone cost will increase in proportion to the time used, and now that data transfer speed is slow as ADSL and the like spread.
2. ISDN Connection (Required equipment: terminal adapter)
ISDN is a digital telephone line standard. It can be used as two lines with one telephone line, and can be used to make a call while connecting to the Internet.
The connection to the provider is made by making a call to the provider through the terminal adapter in the same way as the connection by the "general (analog) line". Connect the PC and the terminal adapter using a telephone line. The speed is a bit faster than "general (analog) line", but it is considerably slower than ADSL etc. Although the telephone charges are in proportion to the time spent using the same as the connection by "general (analog) line".
As for the necessary equipment, "DSU" was previously required other than the terminal adapter, but recently it is not necessary to prepare it as it is often built in the terminal adapter. Also, if you use a device called "Dial-up Router" instead of a terminal adapter, you can connect to the Internet from multiple PCs. Connect the computer and dial-up router using a LAN cable.
CATV Connection (Required equipment: Cable modem most rented from provider)
The CATV connection uses a computer and a cable modem, and connects to the provider through a cable TV line. Generally, the provider will be a cable television company or its affiliate. Connection of cable modem and PC uses LAN cable. Also, the PC side needs a LAN port. If you have a several years old computer, you may not have a LAN port.
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