DEVICES USED in NETWORKING

Network devices are components used to connect computers or other electronic devices together so that they can share files or resources like printers or fax machines.

 The following are some of the devices used in networking:

GATEWAYS

     Gateways are devices which connect two are more networks that use different protocols. They are similar in function to routes but they are more powerful and intelligent devices. A gateway can actually convert data so that network with an application on a computers on the other side of the gateway e.g a get way can receive email messages in one format in convert them into another format. Gateway can operate at all seven layer of OSI model. Since Gateway perform data conversion so they are slower in speed and very expensive devices.

 

 ROUTER

Routers are devices which connect two are more networks that use similar protocol. A router consists of hard ware and software. Hard ware can be a computer is specific device. Software consists of special management program that controls flow of data between networks.  Routers operate at a network layer of O.S.I model.Routers use logical and physical address to connect two or more logically separate network. They make this connection by organizing the large network into logical network segment (some times small sub network or sub nets). Each of these sub nets is given a logical address. Data is grouped into packets or block of data.Each packet in addition to having a physical device address, has a logical address. The network address allows routers to calculate more accurately and efficiently the path of the computer.

REPEATERS

Repeaters are used within network to extend the length of communication.

Data process through transmission media in the farm of waves or signals. The transmission media weaken signals that move through it. The weakening of signal is called attenuation. If the data is to be transmitted beyond the maximum length of a communication media, signals have amplified. The devices that are used to amplify the signals are called repeaters. Repeaters work at the physical layer of OSI model. Repeaters are normally two ports boxes that connect two segments. As a signal comes in one port , it is Regenerated and send out to the other port. The signal is read as 1s and 0s. As 1s and 0s are transmitted, the noise can be cleaned out.

 

BRIDGES

Bridges are used to connect similar network segments.

A bridge does not pass or signals it receives. When a bridge receive a signal , it determines its destination by looking at its destination and it sends the signals towards it. For example in a above figure a bridge has been used to join two network segments A AND B. When the bridge receives the signals it read address of both sender and receiver. If the sender is a computer in segment A and the receiver is also segment A, it would not pass the signals to the segments B. It will however pass signals if the sender is in one segment and the receiver in other segment. Bridge works at the data link layer of O.S.I model.

 the picture above is a media bridge.

 

MODEM

The device that converts digital signals into analog signals and analog signals to digital signals is called Modem. The word modem stands for modulation and demodulation. The process of converting digital signals to analog signals is called modulation. The process of converting analog signals to digital signals is called demodulation. Modems are used with computers to transfer data from one computer to another computer through telephone lines.