What are network devices? Introduction to networking devices?

Network Devices

Modem: The modem consists of Modulator Mo and Demodulator Dem

Voice is an important and widely used electronic device used in computer communication systems. The computer is connected to the telephone line through a modem. As a result, it is possible to send data from a computer to any part of the world through a modem and phone line. In this case, the receiving computer must also be connected to the phone line through a modem. 

The modem's function is to convert a digital signal to an analogue or modulate and Digitalize or demodulate analogue signals. Analogue signals can flow through normal telephone lines, but computers use digital signals. Therefore, the digital signal provided by the computer has to be converted into an analogue signal to be sent over the telephone line. And the work of converting this digital signal into an analogue signal is done by the modem connected to the sending computer. The modem sends the converted signal to the receiver over the telephone line. Digitalized by a modem connected to the sender's computer

The process of converting a signal into an analogue signal is called modulation. When the receiving computer receives data from the telephone line, it converts the analogue signal back into a digital signal through the modem connected to it. The process of converting an analogue signal into a digital signal by a modem connected to the receiving computer is called demodulation.

Modems are of two types based on the mode of use. namely --

(i) Internal Modem 

(ii) External Modem

 

The modem has to be connected to the serial port of the computer. A single bit is sent from the computer to the modem for transmission over the telephone line. The modem converts each bit to an analogue and transmits it over the telephone line.

The minimum transmission speed of the modem is 300 bps (BPS = Bits Per Second). The current modem speed is very high. Modem speed nowadays stands at 57600 bps, 33200 bps, 28800 bps, and 14400 bps. Although modems faster than 9600 bps are used in our country. no Because both analog and digital are still present in our country's telecommunication system. There are two types of modems. namely

1. Acoustic Coupler Modem: The speed of this type of modem is very low. This type of modem is usually used with portable computers. Acoustic coupler modems may also be built-in, such as mobile telephones. Using the speaker and microphone in these modems, the sender and receiver communicate by telephone. Then the data transmission from the computer starts. Although the price is low, such modems are not used nowadays due to the hassle of manual control.

2. Directly connected modems: These types of modems enable fast data transmission. Directly connected modems are of two types. Built-in (Built-in) modem and standalone modem connected with an expansion slot inside the computer. Such modems are also known as smart modems. In this case, the data can be sent by pressing directly from the computer keyboard. Most smart modems have an auto-answer feature.

Hub

A device that connects two or more computers nearby within a computer network is called a hub. How many computers can be connected depends on the number of ports of the hub. Hubs with different numbers of ports are available in the market. For example, hubs are available with 8, 16 or 24 ports. Hub can be purchased according to user needs. A hub is less expensive than a switch, a device that connects computers. Hubs have slower data transfer speeds than switches. There are two types of hubs. namely

1. Active Hub: This type of hub increases the quality of the signal and sends it to the receiving computer.

2. Passive Hub: This type of hub cannot increase signal quality.

An 8-port hub typically has 4 active and 4 inactive ports. Each port inside the hub is connected by a common wire. As a result, whenever data is sent from any terminal, data reaches all computers through each port. 24 computers can be connected by a 24 port rate. If you want to connect more computers than this, you have to connect them to a common port of another hub through a special port located in the hub. Such special ports located at the hub are called uplink ports. The circuit used in the Hub cannot analyze the data coming into it. It cannot send data to multiple terminals simultaneously. If data arrives at the hub from multiple terminals simultaneously, the data may collide.

Router: A router is a type of device used in internetworking. Through this connections can be established between multiple networks. Network expansion is done by using routers. But routers can aggregate multiple networks with the same protocol. Through this, there is less chance of collision in data exchange. The router takes the data sent by the sender along the shortest path to reach the receiver. Through this, data jams on different paths can be observed and data can be sent to alternate paths accordingly.

Gateway: Gateway is a type of interface used in computer networking. Routers, hubs, switches can connect multiple computers or networks but do not facilitate protocol translation. Gateway is used to solve this problem. Gateway performs protocol translation when connecting to another network. Most gateways operate at the Application, Presentation, Session, and Transport layers of the OSI model. However, a gateway can operate at all levels of the ISO reference model by providing some kind of translation facility. Collisions are less likely to occur during data exchange through gateways. Its price is relatively high.

Switch: A computer networking system switch is used as a connecting device. The switch receives the signal from the sender and sends it directly to the receiver computer. A switch is more expensive than a hub and its configuration is relatively complex. In the case of data exchange through switches, weak signals are strengthened by amplifiers. After data arrives at the switch from any port, the electronic circuit used in it analyzes the data and delivers it to the destination computer port. The switch circuit has separate buffer registers for each port, allowing multiple terminals to exchange data simultaneously. Hence there is no possibility of collision in data exchange through it.

Network Interface Card:

A network card is a type of interfacing card. This connection is established between two or more computers. A network card is also called a LAN card. Such cards are placed in the expansion slots of the motherboard. After inserting the LAN card into the expansion slot, it needs to be installed by the driver software developed by its manufacturer. Some motherboards and almost all laptop computers have NICs built-in.

Functions of network:

Nowadays, people of all professions in all countries around the world are enjoying the direct and indirect benefits of computer networks. The following are the functions of a computer network:

1. Through computer networks, the main offices of various banks are able to maintain fast connections with their branch offices and even ATM booths.

2. Through this, people located far away can exchange ideas with each other at a low cost, and even see each other.

3. Online shopping is being done from home using a computer network.

4. Through this, various researchers can collect the necessary information for their research work.

5. Bus or train ticket booking is being done through a computer network, and hotel seat booking is becoming possible.

6. Distributed databases are being used on central computers for information services.

7. Through this, it is possible to read books from the libraries of different countries at home.