Week 8: Networking and Telecommunication Basics

Communication Computer communications is the process of sharing data, programs, and information between two or more computers Numerous applications depend on communication systems, including E-mail Instant messaging Internet telephone Electronic commerce Ask students to give examples of communication devices that they use daily

Communications Today Connectivity uses computer networks to link people and resources The Wireless Revolution Single most dramatic change in connectivity and communications has been widespread use of mobile telephones with wireless Internet connectivity Connectivity is a concept related to using computer networks to link people and resources Microcomputers. minicomputers, and mainframes can all be connected Wireless revolution Use of mobile or wireless devices The revolution is the support of more than just the wireless telephone Many devices can and will connect to one another without any physical connection

Communication Systems Four basic elements Sending and receiving devices Communication channel Connection devices Data transmission specifications Electronic systems that transmit data from one location to another Communication systems can be wired or wireless Basic elements Sending and receiving devices – computer or a specialized communication device Communication channel – carries the message Connection devices – act as an interface between sending and receiving devices; convert outgoing messages into packets (key term) that can travel across the communication channel Data transmission specifications – rules and procedures that coordinate the sending and receiving devices

Communication Channels Communication channels carry the data from one computer to another Two categories of communication channels Physical connection Wireless connection Channels are essential to a communication system They carry data Types of channels Telephone lines (key term) Coaxial cables(key term) Fiber-optic cable (key term) Infrared (key term) Broadcast radio (key term) Microwave (key term) Satellite (key term)

Types of Transmission Media Guided Media : Unshielded Twisted Pair (UTP) Shielded Twisted Pair Coaxial Cable Optical Fibre Unguided Media : Radio Transmission Microwave Satellite Communication

Physical Connections Ethernet cable (Twisted pair cable) Coaxial cable Fiber-optic cable Ethernet cable – consists of twisted pair cable; slowest; being phased out by more advanced and reliable media Coaxial cable – single solid copper core; 80 times transmission of twisted pair; television and computer networks Fiber optic – 26,000 times capacity of twisted pair cable; more secure and reliable; best over limited distances; lighter, more reliable, and less expensive than coaxial cable Return

Wireless Connections Radio frequency (RF) Microwave Satellite Infrared Bluetooth (short-range,10 Mtr) Wi-Fi (wireless fidelity, 100 Mtr) WiMax (1-5 KM) Microwave Satellite Infrared Short distances and line of sight Wireless connections do not use a solid substance to connect; uses the air itself Types of wireless connections are: Infrared Light waves used over short distances Sometimes called line of sight communications Sending and receiving devices must be in clear view of one another Broadcast radio Uses towers called transceivers (key term) Web-enabled devices follow a standard known as Wi-Fi (wireless fidelity) Microwave Uses high-frequency radio waves Also line of sight Used for short distances Satellite uses satellites orbiting about 22,000 miles above the earth as microwave relay stations; many of these offered by Intelsat, the International Telecommunications Satellite Consortium which is owned by 114 governments and forms a worldwide communications system Satellites can be used to send and receive data; Uplink is sending data to satellite and Downlink refers to receiving data from a Satellite GPS (Global Positioning system) use a network of 24 satellites owned and managed by the Defense Department which continuously sends location information to earth Return

Communication Channels Summary

Connection Device Signals Types of signals Analog Digital Signals Sent analog – telephone signals; continuous electronic wave Sent digital – computer signals; presence or absence of an electronic pulse; on/off

Connection Devices Types of modems Telephone modem DSL (digital subscriber line) Cable modem Wireless modem (WWAN) Modem – modulator-demodulator Modulation (key term) is the name of the process for converting from digital to analog Demodulation (key term) is the name of the process for converting from analog to digital Telephone – can be either internal or external; connects computer directly to a telephone line DSL – uses standard phone lines; external and uses either USB or Ethernet Cable – coaxial cable – same as your television; uses either USB or Ethernet Wireless modem Does not use cables Also known as WWAN (wireless wide are network modem) (key term) Signals are sent through the air Transfer Speed or transfer rate (key term)-measured in bits per second (key term); the higher the speed the faster the transfer rate

Networks A computer network is a communication system that connects two or more computers Allows exchange of information and resources A computer network is a communication system that connects two or more computers so that they can exchange information and share resources

Computer Networks Node Client Server Directory server Host Switch Network interface cards (NIC) Network operating systems (NOS) Network administrator Node – any device connected to a network Client – a node that requests and uses resources available from other nodes Server – a node that shares resources with other nodes; dedicated servers specialize in performing specific tasks—could be an application server, communication server, database server, file server, printer server, or Web server Directory server – a specialized server that manages resources such as user accounts for an entire network Host – large centralized computer Switch – the center or central node for other nodes; previously done by something called a hub Network interface cards (NIC) – connects the computer to a network Network operating system (NOS) – software to control and coordinate activities between computers on a network Network administrator – a computer specialist; network administrator

Types of netwoks local-area networks (LANs) wide-area networks (WANs) campus-area networks (CANs) metropolitan-area networks (MANs) home-area networks (HANs)

local-area networks (LANs) The computers are geographically close together (that is, in the same building).

wide-area networks (WANs) The computers are farther apart and are connected by telephone lines or radio waves.

campus-area networks (CANs) The computers are within a limited geographic area, such as a campus or military base.

metropolitan-area networks (MANs) A data network designed for a town or city.

home-area networks (HANs) Introduction to comp. and prog. CS 101 G 964 home-area networks (HANs) A network contained within a user's home that connects a person's digital devices. Mr.Mohammed Rahmath

LAN-MAN-WAN

Network Architecture Arrangement is called topology Types of network topology Legacy Bus Ring Current Star Tree Hybrid Mesh Networks are connections of two or more computers that work together to exchange information and share resources The network architecture describes how the network is arranged and how the resources are coordinated and shared Network architecture also describes how a computer network is configured and what strategies are used  Topology – network arrangement or configuration

Bus Network Each device is connected to a common cable, called a bus or backbone All communications travel along this bus Bus network (key term)– each device handles its own communications control No host Common connecting cable called a bus or backbone Not as efficient as star, but it is low cost and widely used Return

Ring Network Each device is connected to two other devices No central file server or computer Useful in a decentralized environment Ring network (key term) Each device connected to two others forming a ring No central files server or computer Messages passed around ring until reach correct destination Often used to link mainframes—especially over wide geographical areas Useful in decentralized organization Makes possible distributed data processing system (key term) Computers can perform processing tasks on own Can also share programs, data, and other resources Return

Star Network Most widely used network topology for both homes and large businesses Each device connects directly to a central network switch Host – large centralized computer, usually a mainframe Star network (Key Term) – nodes are connected to a single computer called a network hub All communications pass through the switch; each connecting device is asked (“polled”) whether it has a message to send and then each device is in turn allowed to send its message Most widely used network topography today Return

Tree Network Each device is connected to a central node, either directly or through subordinate nodes Also known as a hierarchical network Tree Network (key term) Sometime called a hierarchical network The central node is connected to two or more subordinate nodes that in turn are connected to other subordinate nodes Useful in centralized organization Return

Hybrid Network Combination of different topologies Return

Mesh Network Does not use a specific physical layout, but requires that each node have more than one connection to other nodes Wireless technologies are frequently used Return

Network Topologies

Network Strategies Terminal server network Client/server network Peer-to-peer (P2P) network Distributed processing network Every network has a way of coordinating the sharing of information and resources There are four common strategies: Terminal server network – processing power is centralized in one large computer Terminal Server Client/Server Peer-to-Peer

Networking hardware Networking hardware typically refers to equipment facilitating the use of a computer network. Examples: bridge, hub, routers, switch, modem etc……

Bridge A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments.

HUB HUB - is a device for connecting multiple twisted pair or fiber optic Ethernet devices together and thus making them act as a single network segment.

Routers Routers are small physical devices that join multiple networks together.

Switch A network switch is a small hardware device that joins multiple computers together within one local area network (LAN).

Modem Definition : a combined device for modulation and demodulation, for example, between the digital data of a computer and the analogue signal of a telephone line.

Week 8 End