The Ethernet set of rules that reglamentary not the only way, the order of transmission of information. But also contain clear standards of networking: from the types of equipment that must be connected. To the thickness, the type of cable that this equipment should be connected. Such standardization allows computers residing on different continents quickly "understand" each other. Manufacturers at the manufacturing stage to lay in the necessary equipment functions.
Internet and Ethernet is: what is the difference
Despite the similar sound and spelling, featuring multiple letters, the two concepts, meaning completely different things. The Internet is a global world wide web, bringing together millions of users. From the home grid, which is connected to a PC, laptop and smartphone, it differs only in scale.
The Internet is built on the principle of a chain that fish or Soviet shopping bags. There is no master control center, there are multiple nodes (like the knots on the bag) that send data in different ways (routes). The path selection in networks latest generation rests upon the shoulders of the router. Information travels from one router to another. In earlier embodiments, the signals went on the principle of the separation medium. To absolutely all devices understand each other and do not distort the data entered standards. So they are called technology Ethernet.
To transmit information over any distance, it is necessary to fulfill several conditions:
- the equipment must know how to locate the addressee;
- between the device it is necessary to connect the cable so that no information is lost in the way.
- data should be transmitted so that they do not interfere with each other, quickly slipped from one node to another.
All conditions are governed by the network protocols and international standards. One of them, the most common standard — based Ethernet technology.
Network data transfer: history, methods
Date of establishment of revolutionary methods of transmission distance on new principles is considered in 1975 when the first computer Network company "Xerox" has formulated a set of rules of transportation of packages. It became the basis of alternative II, published after 5 years. It was the last proprietary standard created by Xerox representatives.
Since 1980, over protocols, began working with the Institute of Elecrical and Electronics Engineers (IEEE) Institute of electrical and electronics engineers.
This organization, uniting specialists of different countries, existing since the mid-19th century. It was she who created the technology IEEE 802.3 Ethernet, which was supplemented in 1995 by the rules for connections Fast, and in 1998 — for Gigabit.
Data that should be sent from one PC to another, translate into a system of binary signals transmitted by electrical impulses (Manchester code). Each character beat is divided into two parts. If you pass the unit in the middle of the clock electrical signal is increased if the zero — reduced. So one computer sends to another any of files: from text to music or film. One file contains up to millions of bytes (characters), so it is divided into equal parts packages.
To multiple devices do not interfere with each other to operate, technology transfer Ethernet data is organized according to two principles:
- before sending your PC "listens" if the road is clear, you can forward signals;
- if there is interference, it should stop sending, wait, repeat.
When the simultaneous data transfer of several devices, a conflict may arise: packets will encounter in the road and to the sender will not come. Until one device sends signals to the rest of the "listening" channel. When the recipient knows your address, it opens to reception, the rest of the PC and closed for reception and for transmission. When the packets are gone, they open.
Key features, types of construction of lines of transportation signals
Network transmission of information is based on not a single set of rules, but several. They are designed for lines that have been split by the main user characteristics into 4 groups.
The logic of the first three of the same type, differ only in physical properties:
- Ethernet at speeds of 10 Mbps, the maximum distance between two routers is 2 500 meters. Works on the principle of shared environment, much like a radio broadcast. The pulse is transmitted in all directions, listen to it all, but the reception is only opened by the recipient. Also occurs in two subsequent cases.
- Fast, which began for the first time to use fibre-optic cable brought the speed up to 100 Mbps, but reduces the spacing between nodes is 200 meters. If you are using not only optical fiber but also a twisted pair, a device operating according to this principle, choose a speed from 10 to 100 Mbps. the Size of one pack remains as in the first version of the connection, but 10 times reduced the intervals between sending.
- Gigabit that uses a cable of three types, stores at the lower levels the speed of 100 Mbps, and the communication between the main levels increases it to 1000 megabits/s. For this technology the size of a single packet of information has increased 8 times, has created the ability to send several frames in a row without pause, until their total reaches 8Кбайт, and then take a break. Distance between nodes depends on the cable used for connection. If multimode, do not more than 500 meters. When a single-mode, up to five kilometers, and dual coax — no more than 25 meters.
- Line 10G is used different from the previous three, the principle of information transfer (type of construction): instead of throwing in the space, here pre-planned route with a special device — router. According to it, the package goes with a speed of 10 Gbps, and routers, you can alienate from each other at 40 kilometers. This is called a transmission packet.
To avoid any conflicts in the basis of the connection technology Ethernet, Fast, Gigabit, single principle: listen and then say. Failed — again.
Saved a common way of identification of the addressee. Each device at the stage of production receives its own code or MAC address. This is a unique six pairs of numbers separated by colons that do not change throughout the lifetime of the equipment. That is what the addressee knows that the sender.
The pros and cons
The Ethernet has its advantages and disadvantages. The advantages include:
- low cost to the end user;
- extensive experience in the use (1980);
- large selection of equipment from different manufacturers, which are compatible with each other;
- unlimited development opportunities, thanks to two types of networking.
Such connection can be arranged on the principle of shared environment or packet switching.
Though not without some drawbacks:
- collisions and interference, the standard error of works that were, are and will be;
- with large network load, the transmission time increases tenfold.
Despite the drawbacks, technology continues to develop. Now comes the process of implementation variant of the Gigabit connection working on four pairs of category 5 UTP. Improving fiber-optic cables that are free from collisions, but can not transmit a signal over long distances. It just fades.