Transmission Medium and Devices

Transmission Medium : It is the means through which we send our data from one place to another. The first layer (physical layer) of Communication Networks of Seven layer model is dedicated to the transmission media.

Factors to be considered while choosing Transmission Medium

1. Transmission Rate
2. Cost and Ease of Installation
3. Resistance to Environmental Conditions
4. Distances between the nodes

Types of Cables 

	Speed	Bandwidth	Attenuation
Twisted pair	Moderate	100-500 Mbps	High
Coaxial cable	Low	10 Mbps	Moderate
Optical fiber	High	100 Mbps- 2 Gbps	None

Transmitter : It processes the incoming message signal so as to make it suitable for transmission through a channel and subsequent reception.

Transducer: Any device that converts one form of energy into another can be termed as transducer.

Receiver : A receiver extracts the desired message signals from the received signals at the channel output.

Amplifier: It is a device which increases the amplitude and hence the strength of a signal and the process is known as amplification.

Repeater : In telecommunications, a repeater is an electronic device that receives a signal and re-transmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.

Switch: A network switch is a computer networking device that connects devices together on a computer network.

Hub: A hub is a common connection point for devices in a network.

Bridge: In telecommunication networks, a bridge is a product that connects a local area network (LAN) to another local area network that uses the same protocol .

Gateway: It is a device to connect two dissimilar network.

Modem: It is a device which converts analog signal to digital and vice versa.

                Modem may be of two types 

                              1. Internal Modem

                              2. External Modem

NIC: It is an Ethernet card which contains connection for twisted pair cable or co axial cable.

Router: A router is a networking device that forwards data packets between computer networks. Routers perform the "traffic directing" functions on the Internet.

Difference between Switch and Hub

1. Hub is a dumb device while switch is smarter device than hub.

1. Hub Broadcast the message in network which leads to traffic load while switch sends the packets to only desired destination.