Internet ApplicationsName of ApplicationPurpose of Application

Electronic mail, e-mailEasy to use, inexpensive, asynchronous means of communication with other internet users

Instant messaging (IM)Synchronous communication system that enables that user to establish a private chat room with another individual to carry out text-based communication in real time over the internet

Remote LoginPermits user to log into and perform work on a computer that is remote to the users current location

Usenet newsgroupsInternet discussion groups, which are essentially huge electronic bulletin boards on which grup members can read and post messages

World Wide Web or the WebHypertext-based tool that allows the user to traverse, or surf, the internet, by clicking on a link contained in one document to move to another document, and so on; these documents might include video clips, recordings, photographs, and other images.

Search EngineAn information retrieval program that permits the user to search for content that meets a specific criterion (typically containing a given word or phrase) and retrieves a list of items that match the criterion.

BlogA usr-generated web site where entries are made in journal style; blogs often provide commentary on a particular subject or serve as a personal online diary.

Accessing the InternetHow does an individual user access the internet? In the workplace, most users are connected to a LAN, which in turn is connected to the organizational backbone network, and then to the internet. Today, however, an increasing number of users are employing on of five newer, higher-speed alternatives: Digital subscriber Line (DSL), a cable modem connection, wireless to the home, and fiber to the home.1. Digital Subscriber Line (DSL)DSL is a service offered by telephone companies using the copper wires already installed in homes and offices; it uses a sophisticated modulation scheme to move data over the wires without interfering with voice traffic that is, both a voice conversation and an Internet hookup can be active at the same time over a single DSL Line.2. A Cable modem connectionA Cable modem connection is very competitive to DSL in both price and speed. In this case, the service is obtained from the cable television company, and the data are transmited over the coaxial cables already used by television. These cable have much greater bandwidth than twisted pair copper wires, but traditionally they transmitted data only in one direction-from the cable television company to the home.3. A Satelit ConnectionThe third alternative, a satelit connection, tends to be more expensive option than the first two alternatives, but for customers in rural areas it might be the only choice. Satelit broadband connections can be one-way or two-way service.4. Wireless to HomeWireless to home may be delivered via a city-wide or neighborhood Wi-Fi network, a WiMAX network, or a cellular 3G wireless connection.5. Fiber to the HomeFiber to the home is a newer alternative that is available only in a limited (but growing) geographical area.INTERNET2In reality, Interet2 is not a network type, although it does run a leading-edge, very high-bandwidth network; it is a not-for-profit consortium of over 200 U.S universities, working in cooperation with 70 leading technology companies, 45 government agencies and laboratories. The Internet2 network is a backbone network used by the internet2 universities-it provides an effective interconnection among regional networks that have been formed by the Internet2 universities.NETWORK PROTOCOLSThere is only one more major piece to our network puzzle. How do the various elements of these networks actually communicate with one another? The answer is by means of a network protocol, an agreed-upon set of rules or conventions governing communication among elements of a network, or to be more precise, among layers or levels of a network.OSI REFERENCE MODELBecause of the importance of the OSI model, and because it will give us a conceptual framework to understand how communication takes place in networks, we will briefly discuss how data move through the layers in the OSI model and the role of each of the layers.APPLICATION LAYERApplication layer is an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communication network. The application layer abstraction is used in both of the standard models of computer networking; the internet protocol suite and the open systems interconnection model.PRESENTATION LAYERThe presentation layer is responsible for the delivery and formatting of information to the application layer for the further processing or display. It relieves the application layer of concern regarding syntactical differences in data representation within the end-user systems. An example of presentation service would be the conversion of an EBCDIC-coded text computer file to an ASCII-coded file.SESSION LAYERThe session layer provides the mechanism for opening, closing and managing a session between end-user-application processes, i.e., a semi permanent dialogue. Communication sessions consist of request and responses that occur between applications. Session-layer services are commonly used in application environment that make use of remote procedure calls (RPCs). An example of a session layer protocol is the OSI Protocol suite session-layer protocol, also known as X.225 or ISO 8327.TRANSPORT LAYERIn computer networking, a transport layer provides end-to-end or host-to-host communication services for applications within a layered architecture of network components and protocols. The transport layer provides services such as connection-oriented data stream support, reliability, flow control, and multiplexing.NETWORK LAYERThe network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.DATA LINK LAYERThe data link layer is the protocol layer that transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment. The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer.TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL (TCP/IP)TCP/IP is not part of the OSI reference model, although it roughly corresponds to the network and transport layer. TCP/IP is used in many non-internet networks, including Internet2, as well as in the UNIX and Linux operating systems and in Microsoft windows. TCP/IP is the protocol used on the worldwide internet and on numerous intranets operating within organization. TCP/IP accepts messages of any length, breaks them into pieces less than 64.000 bytes.THE EXPLODING ROLE OF TELECOMMUNICATIONS AND NETWORKING1. Online OperationsThe dominant activities of many organizations have now been placed online to the computer via a network. For banks and other financial institutions, teller stations (as well as automated teller machines) are all online.2. ConnectivityConnectivity is a very popular buzzword among major U.S. and international corporations. Most large and midsized (and many smaller) organizations now provide a personal workstation for every managerial and professional employee, and these workstation are connected to a network structure (often an intranet) so that each employee has access to every person, and every sytem, with which he or she might conceivably need to interact.3. Electronic Data Interchange (EDI)EDI is a set of standards and hardware and software technology that permits documents to be transferred electronically between computers in separate organizations.4. MarketingIn addition to electronic commerce, telecommunication is being used for many other applications in the marketing area. All business organizations sell products and services, although the distribution channels vary widely.THE TELECOMMUNICATIONS INDUSTRYThere are three major segments of the telecommunications industry :1. Carriers, who own or lease the physical plant (cabling, satellites, cellular towers, and so forth) and sell of the service of transmitting communications from one locations to another.2. Equipment vendors, who manufacture and sell a wide range of telecommunications-related equipment, including LAN software and hardware, routers, hubs, wireless access points, switches, multiplexers, cellular telephones, and modems.3. Service providers, who operate networks and deliver services through the network or provide access to or services via the Internet.