Development history Internet

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1. The history of the Internet

The ARPANET was developed and deployed in 1969 by “Bolt, Beranek and Newman” (BBN) by the order of Agency of advanced research projects (ARPA) mini Ministry of defense in order to create a reliable system of information exchange between computers, and also (which was one of the main purposes) for testing techniques maintain communications in case of nuclear attack. The word “safely” assumed a very hard condition: the failure of any components of the system (i.e. computers that are connected by communication lines) should not affect the smooth exchange of information between other local computers. ARPANET allowed each one of their computers to communicate with any other even if failure is an essential part of the network elements.

The founders of ARPANET was originally only allowed scientists to log in and run a program on a remote computer. Soon these increased file transfer, electronic mail and mailing lists, provide communication of researchers, interested in the same area of science and technology. Due to the development of the ARPANET appeared online.

In 1982 to replace the first protocols of the ARPANET came new standards: the standard “Transmission Control Protocol”, describing a method of partitioning informational messages on the packages and their transfer, and “Internet Protocol”, managing the network addressing. These powerful protocols were proposed in 1974 by Robert Ken one of the main developers of the ARPANET, and the scientist-geek by Vinton CERF. Developers from America, England and Scandinavia have begun to create an IP program for every conceivable type of computer. With support from ARPA (advanced research Agency projects) were developed protocols of the gateway exchange for a variety of networks. The practical consequence of this was the possibility of exchanging information between computers from different manufacturers. It has attracted many universities and government agencies, which historically had disparate technology Park and now had an opportunity to exchange information.

In 1983, the communications Agency of the Ministry of defense has decided to use TCP/IP protocols (transmission control Protocol/Internet Protocol) on all host machines of the network arpanet. Thus was set the standard by which to develop the Internet. From this point you can add gateways and connect to the new network, leaving the original kernel intact. In the same year of the early arpanet was divided into MILNET network, destined for military use, and arpanet, focused on the continuation of studies in a network region. Itself network arpanet ceased to exist in June 1990, and its functions gradually shifted to a more branched the structure of the Internet.

The Internet (eng. Internet from lat. between inter and the English. net net, web), international (world) a computer network of electronic communication, uniting regional, national, local, etc. network. Contributes to a significant increase and improvement of exchange of information, especially scientific and technical. Brings together more than 50 million individual and collective users (each with their own e-mail address) all over the world.

The Internet is a global Association of computer networks. It is a vivid example of the concept of inter networks, integrated network that is the web, with-standing from a variety of physically heterogeneous communication networks that are interconnected into a single logical architecture. Internet brings together many of the servers that is a huge amount of information on a variety of topics. Information on servers is organized for user access in various ways. On this basis the most popular are FTP, WWW and Telnet (see Types of servers).

2. E-mail

E-mail is a system for sending messages between users of the computing network. Each user must have an email address that, similar to postal, uniquely identifies the recipient. Sent information (file or with-dialogue) will reach your Inbox anywhere in the network for a few minutes. Obtain information from your mailbox at any convenient time. In addition, the use of e-mail allows you to participate in conferences (exchange of information), for any topics that are organized in global networks.

3. Access to the Internet

First of all, one should distinguish between On-line access to the network giving access to all opportunities provided by Internet: WWW, FTP (see Internet Protocol), etc. -- when this access request processing of the user occurs in real-time and Off-line access when the job network is prepared in advance, and if the connection is only transmitting or receiving the prepared data. Such access is less demanding on the quality and speed of communication channels, but usually gives only the possibility to use E-mail -- e-mail. Although, in fairness, it should be noted that there are servers (primarily the FTP) that allows you to implement basic On-line capabilities through the mail: processing request letter, the computer will take or will pass the appropriate data, and then E-mail forward them, if necessary, to your address. In addition, e-mail, you can subscribe to an online conference on a variety of topics from discussions of literary works to find work or receive stock reports.

4. Internet Protocols

internet network computer protocol

· Network layer:

Internet Protocol (IP) provides best-effort delivery of packet from node to node, in the work with the lower levels uses ARP and RARP.

Address Resolution Protocol (ARP) dynamically translates IP address to physical (MAC).

RARP (Reverse Address Resolution Protocol) inverse ARP, converts the physical address into IP address.

ICMP (Internet Control Message Protocol) controls the transfer of control and diagnostic messages between the gateways and the nodes determines the availability and ability to answer customer contacts, the appointment package, the functionality of routers, etc. ICMP interacts with the upstream TCP/IP protocols. Messages are transmitted using IP datagrams.

· The transport layer:

UDP (User Datagram Protocol) provides best-effort delivery of user datagrams without establishing a connection between the specified processes of the sending and receiving nodes. Interactive processes are identified by Protocol ports (Protocol Ports) - integer in the range 1-65535. Ports 1-255 reserved for the widely known applications (Well-known port assignments), others are assigned dynamically before sending the datagram. UDP datagram has a header that includes the port number of the source (for correct response), the destination port and a data field. The data length of UDP datagram arbitrary, the Protocol provides encapsulation (space in the data field) in one or more IP datagrams and reassembly on the receiving side.

UDP allows multiple clients to use matching ports: the datagram to the supplied to the client (the process) with the specified IP address and port number. If the client is not found, then the datagram is sent to the address 0.0.0.0 (this is usually a "black hole").

Transmission Control Protocol (TCP) provides guaranteed flow of data between clients, establishing a virtual connection. The stream is an unstructured sequence of bytes, and their interpretation is consistent transmitting and receiving side in advance. To identify used ports, similar to UDP ports. The active side (initiator of the exchange) typically uses an arbitrary port, passive is a well - known port that corresponds to the upper layer Protocol. The combination of IP address and port number is called a TCP socket (TCP Socket).

TCP buffers the incoming stream, waiting before sending fill a large datagram. The stream is segmented, each segment is assigned a sequential number. The transmitter waits for acknowledgement of reception of each segment, when his prolonged absence makes retransmission of the segment. The process that uses TCP receives the notification of normal completion of the transfer, only after the build is successful, the flow receiver. The Protocol provides full duplex, that means data flows can go simultaneously in opposite directions.

• The presentation layer and the application layer:

TelNet - remote terminal (character and graphical) UNIX machines.

FTP (File Transfer Protocol) - Protocol file transfer based on TCP.

TFTP (Trivial File Transfer Protocol) - trivial file transfer Protocol based on UDP.

SMTP (Simple Mail Transfer Protocol) is a Protocol for sending e-mail specifying the rules of interaction and control message formats.

RIP (Routing Information Protocol) - a Protocol trace information between routers provide dynamic routing.

DNS (Domain Name System) is the system of ensuring conversion of symbolic names and aliases of networks and hosts into IP addresses and back.

SNMP (Simple Network Management Protocol) simple network management Protocol resources

Remote Procedure Call (RPC) Protocol remote procedure call (start processes on the remote computer).

NFS (Network File System) is an open specification network file system intro-duced by Sun Microsystems.

Among the application level protocols the most commonly used FTP, HTTP, Telnet, and SMTP and POP.

The file transfer Protocol (File Transfer Protocol, FTP) provides file transfer from server file system to the local file system of the client and Vice versa (see Types of servers).

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