NETWORKS

CONTENT DATA TRANSMISSION HARDWARE TRANSMISSION MEDIA DEFINITION DATA TRANSMISSION HARDWARE TRANSMISSION MEDIA TYPES OF NETWORKS TOPOLOGIES EVALUATION

WHAT IS A NETWORK A computer network, or simply a network, is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information

DATA TRANSMISSION Bandwidth describes how much data can be transmitted at a time. The greater the bandwidth, the faster the information can flow. The speed of transmission is measured in baud. The types of bandwidth are: Narrowband transmission Voice band transmission Broadband transmission

NARROWBAND A small bandwidth that can transmit only 10 – 30 characters per second. Used for telegraphy. (Not used anymore)

VOICE BAND Can transmit about 1000 – 8000 characters per second. It is used on telephone lines.

BROADBAND Allows up to hundreds of thousands of characters to be transmitted per second

TRANSMISSION MODES There are three data transmission modes Simplex Half duplex (Full) Duplex

SIMPLEX Data is transmitted in one direction only. Example a television

HALF DUPLEX Data is sent and received but not at the same time. Example a walkie talkie.

(FULL) DUPLEX Data is sent and received at the same time. Example a telephone

HARDWARE IN A NETWORK COMPUTER TERMINALS This is the computer from which users will perform tasks

HARDWARE IN A NETWORK HUB This device allows data to be communicated between hardware devices in a network. It is used in small networks only

HARDWARE IN A NETWORK SWITCH It is the same as a hub but more intelligent. It also directs the flow of traffic between devices. It is used on larger networks

HARDWARE IN A NETWORK ROUTER This device moves data between different networks

HARDWARE IN A NETWORK SERVER This is a computer whose purpose is to ‘serve’ the needs of users on a network. According to the need, a server may be a file server, a mail server, a print server, a web server

TRANSMISSION MEDIA Data must be transmitted using some medium. Media used to transmit data can be: Wired (cable) Wireless

WIRED MEDIA Twisted Pair Cable A cheap form of cabling used in small networks. Advantage: Inexpensive Thin and Flexible Cross talk is minimized Disadvantage: Susceptible to electromagnetic interference Not suitable for sending video

TWISTED PAIR CABLE

WIRED MEDIA Coaxial Cable Cabling used in networks but better suited for transmitting audio sounds. It is used now for connecting television cable receivers. Advantage: Suitable for short distances Inexpensive Supports multiple channels Disadvantage: Noisy High Installation cost

COAXIAL CABLE

WIRED MEDIA Fiber Optic Fiber-optic is a cable used to transmit information from one place to another by sending pulses of light through an optical fiber. Advantages Good bandwidth and capacity Immunity to electrical noise Disadvantages: Expensive Not widely available

OPTICAL FIBRE

WIRELESS MEDIA Communication Satellites Also called comsat is an artificial satellite sent to space for the purpose of telecommunications. provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radio broadcasting

COMMUNICATION SATELLITES

WIRELESS MEDIA Infrared This is used in short-range communication among computer peripherals and other devices. Devices use infrared light-emitting diodes (LEDs) to emit infrared radiation. The beam is switched on and off, to encode the data. The receiver converts the infrared radiation to an electric current. Infrared communications are useful for indoor use in areas of high population density. It does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances

INFRARED

WIRELESS MEDIA Bluetooth This is a wireless technology standard for exchanging data over short distances using short-wavelength radio transmissions from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. USES: Wireless Bluetooth headset and Intercom For input and output devices such as wireless mouse and keyboard.

BLUETOOTH

WIRELESS MEDIA Wi-Fi Wi-Fi is a popular technology that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed Internet connections. Devices like PC’s smartphone, tablet and game consoles use Wi-Fi to connect to a network or the Internet via a wireless network access point or a hotspot.

Wi-Fi

TOPOLOGY Topology refers to the layout of connected devices. This article introduces the standard topologies of networking. TYPES OF TOPOLOGIES Bus Star Token Ring Mesh Tree

BUS  Bus network topology is a network architecture in which a set of clients are connected via a shared communications line/cables, called a bus.

STAR  Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch. The switch is the server and the peripherals are the clients

TOKEN RING Stations on a token ring LAN are logically organized in a ring topology with data being transmitted sequentially from one ring station to the next with a control token circulating around the ring controlling access.

MESH Mesh networking is a type of networking where each node must not only capture and send its own data, but also serve as a relay for other nodes, that is, it must work with others to send the data in the network.

TREE This is a combination of the bus and the Star Topology. The tree like structure allows you to have many servers on the network and you can branch out the network in many ways.

TYPES OF NETWORKS LAN MAN WAN INTERNET INTRANET EXTRANET

LAN Local Area Network A computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media.

Example

MAN Metropolitan Area Network This is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links.

Example 1

Example 2

WAN Wide Area Network This is a network that covers a broad area (i.e., any telecommunications network that links across metropolitan, regional, or national boundaries) using private or public network transports

Examples

COMPARISONS

COMPARISONS

INTERNET The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP.) to serve billions of users worldwide

Example

INTRANET An intranet is a private computer network that uses Internet Protocol technology to share information, operational systems, or computing services within an organization

EXTRANET This is a computer network that is similar to an intranet but allows controlled access from the outside, for specific business or educational purposes. It extends access to users outside the organization, usually partners, vendors, and suppliers, in isolation from all other Internet users.

COMPARISON

COMPARISON 2

EVALUATION

Question 1 Question 2 Question 3 Question 4 Question 5 Question 6

Question 1: Which bandwidth can be used for Internet connection?

Question 2 What transmission mode does a pager use?

Question 3 Which of the three networking devices is the most intelligent? a. Hub b. Router C. Switch

Question 4 Which wired media has a copper interior?

Question 5 A private network that uses Internet Protocol

Question 6 A private network that allows authorized outsiders to access its network.

BROADBAND TRANSMISSION

SIMPLEX

SWITCH

COAXIAL CABLE

INTRANET

EXTRANET