Networks Unit 5 Digital Literacy Computer Technology (S3 Obj 2-1, 2-2 & 2-3)

Network  A computer network, or simply a network, is a collection of computers and other hardware components interconnected by communication channels that allow sharing of resources and information.

Network Beginnings  The Defense Advanced Research Projects Agency (DARPA) funded the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. The first operational computer network in the world began in 1969 based on designs from the 1960’s.

Interested in more info on ARPANET?  Click on the picture below to view an 8 minute video. ARPANET Team

Properties of a Network  Facilitates communications  Permits sharing of files, data, and other types of information  Share network and computing resources (i.e. network printer)  May be insecure  May interfere with other technologies  May be difficult to set up

Properties of a Network  Facilitates communications Using a network, people can communicate easilyvia , instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.  Permits sharing of files, data, and other types of information In a network environment, authorized users may access data and information stored on other computers on the network.

Properties of a Network  Share network and computing resources In a network environment, each computer on a network may access and use resources provided by devices on the network, such as a shared network printer.

Properties of a Network  May be insecure A computer network may be used by hackers to deploy computer viruses and computer worms on devices connected to the network or to prevent these devices from accessing the network.

Properties of a Network  May interfere with other technologies Power line communications can disturb certain forms of radio communication, e.g. amateur radio.  May be difficult to set up A complex computer network may be difficult and very costly to set up, particularly in a large organization or company.

Types of Network Wiring  Twisted pair Used for telecommunication  Coaxial cable Television, office buildings and LANs  ITU-T b.hn Uses home wiring (Coaxial able, phone lines, etc.)  Optical Fiber Cable Glass fiber

Wireless Networks  Terrestrial microwave  Communications satellites  Cellular and PCS systems  Wireless LANs  Infrared Communication  Global Area network (GAN)

Wireless Networks  Terrestrial microwave Use earth-based transmitters and receivers like satellite dishes  Communications satellites Use microwave radio as medium. Satellites stationed in space  Cellular and PCS systems Use several radio communications technologies  Wireless LANs Use a high-frequency radio technology using spread spectrum technology

Wireless Networks  Infrared Communication Can transmit signals between devices within small distances, typically no more than 10 meters (Blue Tooth)  Global Area Network (GAN) A network used for supporting mobile communication across an arbitrary number of wireless LANs, satellite coverage areas, etc.

Network Classifications  Personal Area Network (PAN)  Local Area Network (LAN)  Home Area Network (HAN)  Campus Area Network (CAN)  Metropolitan Area Network (MAN)  Wide Area Network (WAN)  Internetwork (Internet)

Personal Area Network (PAN)  A network used for communication among computers and devices close to one person.

Local Area Network (LAN)  Computer network that is located within a limited geographical area, such as a school or small business Example  The DHS Network

Home Area Network (HAN)  A residential LAN connecting a small number of personal computers and accessories.

Campus Area Network (CAN)  A computer network made up of an interconnection of LANs within a limited geographical area.

Metropolitan Area Network (MAN)  A large computer network that spans the area of a large city or a large campus.

Wide Area Network (WAN)  Interconnected group of computers and peripherals that cover a large geographical area, such as multiple buildings Examples  The Davis School District Network  The Internet

Internetwork (Internet)  An internetwork is the connection of multiple computer networks via a common routing technology using routers.  The Internet is a collection of many connected internetworks spanning the Earth.

Network Terms  File Server A computer connected to a network that distributes resources to other users  Contains the software to manage and process files for other network users  Host Computer Refers to any computer that provides services to network users  Often associated with the Internet

Network Terms  Workstation Refers to a personal computer connected to a network  Example Each computer in the classroom  Client Refers to the software on a computer that allows the user to access the server  Example Microsoft Client Software

Network Interface Card (NIC)  Small circuit board that coverts the digital signals from a computer into signals that can travel over a network  Desktop Computers have the NIC inside the case with a jack on the outside for the network cable Example  Our classroom computers  Notebook or Laptop Computers have a special card that fits into a slot or opening in the case.

IP Addresses  A unique identifying number assigned to each computer connected to the internet Example – Each computer on a network should have its own separate IP Address or conflicts will occur when there are duplicate addresses  IPv6 is the successor to the Internet's first addressing infrastructure

WiFi  A mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point.

Network Connections Devices  Modem A device that sends and receives data to and from computers over telephone lines.  Hubs A device that connects several components of a network  Routers A device that connects at least two networks  Gateway A device that serves as an entrance to another network  Switch A network switch or switching hub is a computer networking device that connects network segments or network devices  All of these can be used alone or in a combination

The End! Use these notes to complete the Review Activity!

Resources Parsons, June Jamrich, and Dan Oja. Computer Concepts. Boston: Course Technology - Thompson Learning, networks