CHAPTER 6

CHAPTER 6

Networks

Chapter Outline

  6.1 What Is a Computer Network?

  6.2 Network Fundamentals

  6.3 The Internet and the World Wide Web

  6.4 Network Applications

•        A computer network is a system that connects computers and other devices via communications media so that data and information can be transmitted among them.

Size of Computer Networks

•               Home computer network
•               National computer network
•              Global computer network

•       A local area network connects two or more devices in a limited geographical region so that every device on the network can communicate with every other device.

Enterprise Network

Network Fundamentals

Analog and Digital Signals

Communications Media and Channels

Twisted-pair wire

Fiber optics

Coaxial cable

Transmission Technologies

•          Digital Subscriber Line: a high-speed, digital data transmission technology using existing analog telephone lines.
•          Asynchronous Transfer Mode: data transmission technology that uses packet switching and allows for almost unlimited bandwidth on demand.
•          Synchronous Optical Network: an interface standard for transporting digital signals over fiber optic lines that allows users to integrate transmissions from multiple vendors.
•         T-Carrier System: digital transmission system that defines circuits that operate at different rates, all of which are multiples of the basic 64 Kbps user to transport a single voice call.

The Four Layers of the TCP/IP Protocol

Packet Switching

See video about  

Circuit switching & Packet switching

Accessing the Internet
Connecting via an online service	Cable Modem
Internet kiosks	Satellite
Dial-up	Wireless
DSL	Fiber to the Home

Addresses on the Internet

See video about

IP Address - Internet Protocol Addres

•       Domain names consist of multiple parts, separated by dots, which are red from right to left.
•       Top-level domain: the rightmost part of an Internet name; common top-level domains are .com, .edu, .gov.
•       Name of the company: the next section of the Internet name.
•       Name of the specific computer: the next section of the Internet name.
•      World wide web: A system of universally accepted standards for storing, retrieving, formatting, and displaying information via a client/server architecture.

Browser Competition

Network Applications

Discovery

•          Discovery allows users to browse and search data sources, in all topic area on the Web.
•        Search engines are computer programs that search for specific information  by key words and report the results.
•        Metasearch engines search several engines at once and integrate the findings of the various search engines to answer queries posted by users

.

Portals

n  Commercial (public) portals

n  Affinity portals

n  Mobile portals

n  Corporate portals

n  Industry wide portals

     Communication

•       Electronic mail (e-mail) is the largest-volume application running on the Internet.

        

•         Web-based call centers (customer call center) are services that provide effective personalize customer contact as an imporant part of Web-based customer support.

•        Electronic chat room is a virtual meeting place where groups of regulars come to “gab”.
•        Virtual collaboration is the use of digital technologies that enable organizations or individuals to collaboratively plan, design, develop, manage and research products, services and innovative applications.
•        Workflow technologies facilitate the movement of information as it flows through the sequence of steps that make up an organization’s work procedures.
•        Groupware refers to software products that support groups of people who share a common task or goal and who collaborate to accomplish it.
•        Web conferencing is videoconferencing conducted over the Internet.
•       Real-time collaboration tools support synchronous communication of graphical and text-based information i.e. computer-based whiteboards.

E-Learning and Distance Learning
Benefits	Drawbacks
Self-paced learning increases content retention.	Instructors may need training to be able to teach electronically.
Online materials deliver high-quality, current content.	The purchase of additional multimedia equipment may be necessary.
Training costs can be reduced	Students must be computer literate and may miss the face-to-face interaction with instructors.

Telecommuting
	Benefits	Disadvantages
For Employees	Reduced stress, improved family life. Employment opportunities for single parents.	Feelings of isolation No workplace visibility
For Employers	Increased productivity. Ability to retain skilled employees	Difficulties in supervising work Additional training costs