Basic lesson before starting internet

Title:Basic lesson before starting internet

By: Amritpal singh sandhuRoll no: 115355

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Main Points:

ModemTypes of NetworksTypes of Transmission MediaThe InternetThe Global Internet

Functions of the ModemFunctions of the Modem

Figure 7-5

ModemModem

The digital signals can be sent to other computers over analog cables such as telephone lines. Note that digital signals are representations of the two binary digits, 0 and 1, and are represented as on and off electrical pulses.

• Signals: digital vs. analog

• A modem is a device that translates digital signals from a computer into analog form so that they can be transmitted over analog telephone lines.

• The modem also translates analog signals back into digital form for the receiving computer.

Modem

• Types of networks1. Local-area networks (LANs)

• Client/server or peer-to-peer• Ethernet –

• dominant LAN standard at the physical network level

• Specifying the physical medium to carry signals between computers

• Data transfer rate: 10 Mbps• New version: Fast Ethernet and Gigabit

Ethernet• Topologies: star, bus, ring

Types of NetworksTypes of Networks

Network TopologiesNetwork Topologies

Figure 7-6The three basic network topologies are the bus, star, and ring.

Management Information SystemsManagement Information SystemsChapter 7 Telecommunications, the Internet, and Wireless TechnologyChapter 7 Telecommunications, the Internet, and Wireless Technology

Communications Networks

• In a star topologyall devices on the network connect to a single hub and all network traffic flows through the hub

• In a bus topologyone station transmits signals, which travel in both directions along a single transmission segment. All of the signals are broadcast in both directions to the entire network. All machines on the network receive the same signals, and software installed on the client’s enables each client to listen for messages addressed specifically to it


• A ring topology connects network components in a closed loop. Messages pass from computer to computer in only one direction around the loop, and only one station at a time may transmit. The ring topology is primarily found in older LANs using Token Ring networking software


2. Campus-area networks (CANs)

3. Wide-area networks (WANs)

4. Metropolitan-area networks (MANs)


• Physical transmission media• Twisted wire (modems) • Coaxial cable• Fiber optics and optical networks

Many of the telephone systems in buildings had twisted wires installed for analog communication, but they can be used for digital communication as well. Also, today, telecommunications companies are starting to bring fiber optic cable into the home for high-speed Internet access.

Types of Transmission MediaTypes of Transmission Media

• Wireless transmission media and devices• Microwave• Satellites• Cellular telephones

• Transmission speed • Hertz• Bandwidth

Types of Transmission MediaTypes of Transmission Media

BP Amoco’s Satellite Transmission SystemBP Amoco’s Satellite Transmission System

Figure 7-7Communication satellites help BP Amoco transfer seismic data between oil exploration ships and research centers in the United States.

Management Information SystemsManagement Information SystemsChapter 7 Telecommunications, the Internet, and Wireless TechnologyChapter 7 Telecommunications, the Internet, and Wireless Technology

Communications Networks

• What is the Internet?• Connecting to the Internet

• Internet service providers (ISPs)• Services

• DSL, cable, satellite, T lines (T1, T3)• T lines are leased, dedicated lines suitable for businesses or

government agencies requiring high-speed guaranteed service levels.

The InternetThe Internet

• Internet addressing and architecture

• IP addresses (Define?)

• The domain name system• Hierarchical structure• Top-level domains


The Domain Name SystemThe Domain Name System

Figure 7-8The Domain Name System is a hierarchical system with a root domain, top-level domains, second-level domains, and host computers at the third level.


• The Future Internet• The IP addresses currently in use, such as

208.55.112.34 are part of a specification called IP v 5. However, given the growth rate of the Internet, there aren’t enough IP addresses in this scheme to last beyond 2013. IP v 6 is a revised addressing convention that will provide over a quadrillion addresses

• IPv6 • Internet2, NGI


• Internet services• E-mail• Chatting and instant messaging• Newsgroups• File Transfer Protocol (FTP)• World Wide Web

• Voice over IP (VoIP)• Unified communications: When firms are able to

merge disparate communications modes into a single universally accessible service

• Virtual private networks (VPNs): is a secure, encrypted, private network that has been configured within a public network to take advantage of the economies of scale and management facilities of large network, such as the Internet


Client/Server Computing on the InternetClient/Server Computing on the Internet

Figure 7-10Client computers running Web browser and other software can access an array of services on servers over the Internet. These services may all run on a single server or on multiple specialized servers.


How Voice over IP WorksHow Voice over IP Works

Figure 7-11

An VoIP phone call digitizes and breaks up a voice message into data packets that may travel along different routes before being reassembled at the final destination. A processor nearest the call’s destination, called a gateway, arranges the packets in the proper order and directs them to the telephone number of the receiver or the IP address of the receiving computer.


• An VoIP phone call digitizes and breaks up a voice message into data packets that may travel along different routes before being reassembled at the final destination. • A processor nearest the call’s destination, called a gateway, arranges the packets in the proper order and directs them to the telephone number of the receiver or the IP address of the receiving computer.

•Skype, acquired by eBay, offers free VoIP worldwide using a peer-to-peer network.


A Virtual Private Network Using the InternetA Virtual Private Network Using the Internet

Figure 7-12

This VPN is a private network of computers linked using a secure “tunnel” connection over the Internet. It protects data transmitted over the public Internet by encoding the data and “wrapping” them within the Internet Protocol (IP). By adding a wrapper around a network message to hide its content, organizations can create a private connection that travels through the public Internet.


• The World Wide Web• HTML (Hypertext Markup Language):

• Formats documents for display on Web• Hypertext Transfer Protocol (HTTP):

• Communications standard used for transferring Web pages

• Uniform resource locators (URLs): • Addresses of Web pages• E.g.,

http://www.megacorp.com/content/features/082602.html

• Web servers• Software for locating and managing Web pages


• Search engines• Started in early 1990s as relatively simple software

programs using keyword indexes• Google visited 50 billion web pages in 2007

• Today, major source of Internet advertising revenue via search engine marketing, using complex algorithms and page ranking techniques to locate results• Sponsored links vs. organic search results

The Global InternetThe Global Internet

• At the foundation of Google’s search engine are two concepts – page ranking and the indexing of combinations of words

• How google works?• The Google search engine is continuously crawling the

Web, indexing the content of each page, calculating its popularity, and storing the pages so that it can respond quickly to user requests to see a page. The entire process takes about one-half second.

• Shopping bots • Use intelligent agent software for searching Internet for

shopping information


How Google WorksHow Google Works

Figure 7-13The Google search engine is continuously crawling the Web, indexing the content of each page, calculating its popularity, and storing the pages so that it can respond quickly to user requests to see a page. The entire process takes about one-half second.


Major Web Search EnginesMajor Web Search Engines

This graphic ranks the major search engines according to popularity, or percentage of total number of searches performed. Google is a clear favorite. Is this due to the superiority of their search engine or does it involve other factors?


Education

Basic lesson before starting internet