COMPUTER NETWORK

- A network is a collection of computers and devices connected via communication devices and transmission media.

Communication Device & Transmission Media

Communication Devices

- A communication  device is any type of hardware capale of transmitting data, instructions, and information between a sending device and receiving device.

Devices	Description
Dial-up Modem	A communications device that can convert digital signals to analog signals and analog signals to digital signals, so that data can travel along an analog telephone line.
Digital Modem (ISDN,DSL, Cable Modem)	A communications device that sends and receives data and information to and from a digital line.
Wireless Modem	Some mobile users have a wireless modem that uses the cell phone network to connect to the Internet wirelessly from a notebook computer, a smart phone, or other mobile device.
Network Card	Sometimes called a network interface card, is a communications device that enables a computer or device that does not have built-in networking capability to access a network.
Wireless access point	A central communications device that allows computers and devices to transfer data wirelessly among themselves or to transfer data wirelessly to a wired network .
	*Wireless access points have high-quality antennas for optimal signals.
Router	A communications device that connects multiple computers or other routers together and transmits data to its correct destination on a network.
Switch	A connection device similar to a hub but more sophisticated, including functionality that allows it to control and manage data transmissions.
Hub	A connection device that allows multiple connections to the network.

Transmission Media

- Materials and substance capable of carrying one or more signals in a communications channels. 

Types of tranmission media :

1. Physical Transmission Media/Guided Media/Wired

• Twisted-pair cable, Coaxial Cable, Fibre-Optic Cable 

2. Logical Transmission Media/Unguided Media/Wireless

• Infrared, Broadcast Radio, Cellular Radio, Microwave, Communications Satellite

1. Physical Transmission Media
Twisted Pair Cable	•Twisted-pair cable consists of one or more twisted-pair wires bundled together.
	•Widely used transmission media for network cabling and telephone systems.
Coaxial Cable	Consists of a single copper wire surrounded by at least three layers:
	1.An insulating material
	2.A woven or braided metal
	3.A plastic outer coating .
Fiber optic	A transmission media that uses glass or plastic fiber to carry light (laser) signals.