1. Week 8: Networking and Telecommunication Basics

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

3. 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

4. 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

5. 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)

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

7. 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
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8. 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
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9. Communication Channels Summary

10. 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

11. 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

13. 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

14. 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

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

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

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

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

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

20. 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

21. LAN-MAN-WAN

24. 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

25. 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
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26. 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
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27. 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
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28. 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
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29. Hybrid Network
Combination of different topologies
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30. 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
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31. Network Topologies

32. 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

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

34. 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.

35. 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.

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

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

38. 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.

39. Week 8 End