The Technology 4 U

Network Communications Technologies - Specific combinations of hardware and software that allow different devices on several types of networks to communicate. • Ethernet , the most popular LAN, is based on a bus topology, but can be wired in a star pattern. This LAN technology enables personal computers to contend for access to the network. Variations of the Ethernet standard include Fast Ethernet and Gigabit Ethernet. • Token ring controls access to the network by requiring that network devices share or pass a token or special signal to access the network. • Internet transmissions commonly use transmission control protocol/Internet protocol, or TCP/IP , to manage data transmission by breaking it up into packets. The 802.11 specification is used for wireless LANs. • The Wireless Application Protocol (WAP) uses a client/server network and allows wireless mobile devices to access the Internet and its services such as the Web and e-mail.

Network Topology - Configuration or physical arrangement of devices in a communications network. Networks usually use combinations of three topologies. Topology 1. Bus Network - Consists of a single central cable, to which all computers and other devices connect. Bus is physical cable or backbone. Inexpensive and easy to install. 2. Ring Network - Cable forms closed ring, or loop, with all computers and devices arranged along ring. Data travels from device to device around entire ring, in one direction. 3.Star Network - All devices connect to a central computer, called the hub. All data transferred from one computer to another passes through hub.

Networks • A collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users.Sharing resources include data & information , software and communication. •A network interface card is used to connect a computer to a network of other computers. A server is any computer that accepts requests from other computers that are connected to it and shares some or all of its resources, such as printers, files, or programs, with those computers. Connecting computers this way is called a client/server network.  •The server runs software that coordinates the information flow among other computer called clients. Network operating system is the software that runs on the server. • A network that works over a relatively short distance (no more than a few thousand feet ) is called a local area network (LAN) . Wide area network -  Network that covers large geographic area. Internet is wo

Wireless Transmission Media - send communications signals through air or space. Used when inconvenient, impractical, or impossible to install cables. Types Wireless Transmission Media 1. Broadcast Radio – distributes radio signals through the air over long distances such as between cities, regions and countries and short distances such as within am office or home. Transfer rate = up to 54 Mbps *BluetoothTM – uses short-range radio waves to transmit data at a rate of 1 Mbps among BluetoothTM-enabled devices. To communicate between each other a small chip is embedded in the devices. BluetoothTM enabled devices include desktop PC, notebook PC, hand-held computers, Internet appliances, cellular telephones, fax machines and printers. 2. Cellular Radio – a form of broadcast radio that is used widely for mobile communications, specifically wireless modems and cellular telephones. Transfer rate = 9,600 bps to 384 Kbps *Personal Communication Sevices (PCS) is asset of technologi

Physical Transmission Media - Wire, cable, and other tangible (touchable) materials used to send communications signals. Type 1. Twisted pair cable - consists of one or more twisted pair wires bundles together. Each cable has two separate copper wires that are twisted together. These wires are twisted together to reduce noise. * Noise – an electrical disturbance that can degrade communication. 2. Coaxial cable - usually referred as coax, consists of a single copper wire surrounded by at least three layers : (a) insulating material (b) a woven or braided metal (c) a plastic outer coating Cable TV wiring usually uses coaxial cable because it can be cabled over longer distances than twisted pair cable. 3. Fiber-optic Cable – consists of dozens or hundreds of thin strands of glass or plastic that use light to transmit signals. Each strand called an optical fiber is as thin as a human hair. Inside the fiber -optic cable, an insulating glass cladding and a protective c

Computer Communications - Describes a process in which one computer transfers data, instructions and information to another computer(s). Some devices that can serve as sending and receiving devices in a communication system are: (a) personal computers (b) notebook computers (c) Web-enabled cellular telephones (d) Web-enabled handheld computers (e) WebTV™ (f) GPS receivers The primary function of a communications device such as a modem is to convert or format signals so they are suitable for the communications channel or a receiving device. When using a telephone line as the communication channel, you need to convert between analog and digital signals. An analog signal consists of a continuous electrical wave. Computers however, process data as digital signals. A digital signal consists of individual electrical pulses that represent the bits grouped together as bytes. Circuit Switching vs Packet-Switching • Circuit switching – centrally controlled, single-connection me

World Wide Web (WWW) -A subset of the computers on the Internet that are connected to each other in a specific way that makes those computers and their contents easily accessible to all computers in that subset. A worldwide collection of electronic documents called Web page that contain text, graphics, sound, video, and links to other Web pages. A Web site is a collection of related Web pages. A home page is the starting page for a browser. It is also called the Index page. It provides information about the web site’s purpose and content. A Web browser is software that lets users read HTML documents and move one HTML document to another. A graphical user interface (GUI) is a way of presenting program output using pictures, icons, and other graphical elements instead of just displaying text. The GUI interface presented in Web browsers has been an important element in the rapid growth of the Web. When you use your Internet connection to become part of the Web, your computer bec

Ways to access the Internet Internet Service Providers (ISP) – a business that has a permanent Internet connection and offers temporary internet connections to individuals and companies free or for a fee. 1. Regional ISP – ISP that provides access to the Internet through one or more telephone numbers local to a specific  geographic area. 2. National ISP – Type of ISP that provides access to the Internet through local telephone numbers in major cities and towns nationwide and usually offer more services and generally have a larger technical support staff than regional ISPs. 3. Online Service providers (OSP) – Business that provides access to the Internet, as well as members-only features that offer a variety of special content and services. 4. Wireless Service provider (WSP) – Company that provides wireless internet access to users with wireless modems or web- enabled handheld computers or devices. How Data travels the Internet Using a telephone Line Connection 1. You i

What is Internet? Sometimes called “the Net”- is a worldwide system of computer networks. The Internet is connecting computers across almost all countries around the world. It enables you to require a file or document from elsewhere in the world virtually The best Virtual Learning, information highway. History of the Internet In the early 1960s, the U.S. Department of Defense (DOD) began a research project authorized as a part of national security. The Defense Advanced Research Projects Agency (DARPA) began examining ways to connect all large mainframe computers to each other and to weapons installations that were distributed all over the world. In 1969, DARPA connected the first computer switches at the University of California at Los Angeles, SRI International, the University of California at Santa Barbara and the University of Utah. This experimental WAN, called the ARPANET, grew over the next three years to include over 20 computers. ARPANET uses the Network Control Protoc

Information security means protecting information and information systems from unauthorized access, use, disclosure, disruption, modification, or destruction. Information Security is a well-informed sense of assurance that the information risks and controls are in balance.-Jim Anderson Inovant (2002) Information Security objective is to protecting the interests of those relying on information, and the system and communications that deliver the information from harm resulting from failures of confidentiality, availability and integrity (CIA).