Data Communication Chapter 6

bus topology

(also called linear bus) connects nodes along a network segment, but the ends of the cable are not connected, as they are in
a ring topology

centralized processing

all processing is done at one central computer

centralized routing

one node is in charge of selecting the path for all packets. This node, considered the network routing manager, stores the
routing table, and any changes to a route must be made at this node

client/server model

software runs on the local computer (the client) and communicates with the remote server to request information or services.
A server is a remote computer on the network that provides information or services in response to client requests

Code Division Multiple Access (CDMA)

transmits multiple encoded messages over a wide frequency and then decodes them at the receiving end

Communication media

or channels, connect sender and receiver devices. They can be conducted or radiated

Conducted media

provide a physical path along which signals are transmitted, including twisted pair cable, coaxial cable, and fiber optics

controller

a hardware and software device that controls data transfer from a computer to a peripheral device (examples are a monitor, a
printer, or a keyboard) and vice versa

convergence

refers to integrating voice, video, and data so multimedia information can be used for decision making

Data communication

the electronic transfer of data from one location to another

decentralized processing

each user, department, or division has its own computer (sometimes called an organizational unit) for performing processing
tasks

Digital subscriber line (DSL)

a common carrier service, is a high-speed service that uses ordinary phone lines

Distributed processing

maintains centralized control and decentralizes operations. Processing power is distributed among several locations

Distributed routing

relies on each node to calculate its own best possible route. Each node contains its own routing table with current information
on the status of adjacent nodes so packets can follow the best possible route

dynamic router

can build tables that identify addresses on each network

hierarchical topology

(also called a tree topology) combines computers with different processing strengths in different organizational levels

mesh topology

(also called plex or interconnected), every node (which can differ in size and configuration from the others) is connected to
every other node.

metropolitan area network (MAN)

designed to handle data communication for multiple organizations in a city and sometimes nearby cities as well

mobile network

(also called a cellular network) is a network operating on a radio frequency (RF), consisting of radio cells, each served by a
fixed transmitter, known as a cell site or base station

modem

(short for modulator-demodulator) is a device that connects a user to the Internet

multiplexer

a hardware device that allows several nodes to share one communication channel

n-tier architecture

attempts to balance the workload between client and server by removing application processing from both the client and
server and placing it on a middle-tier server

network interface card (NIC)

a hardware component that enables computers to communicate over a network

network topology

represents a network's physical layout, including the arrangement of computers and cables

Open Systems Interconnection (OSI)

a seven-layer architecture for defining how data is transmitted from computer to computer in a network, from the physical
connection to the network to the applications that users run. It also standardizes interactions between network computers
exchanging information.

packet

a collection of binary digitsincluding message data and control characters for formatting and transmittingsent from computer
to computer over a network

Protocols

rules that govern data communication, including error detection, message length, and transmission speed

Radiated media

uses an antenna for transmitting data through air or water

ring topology

no host computer is required because each computer manages its own connectivity

router

a network connection device containing software that connects network systems and controls traffic flow between them

Routing

the process of deciding which path to take on a network. This is determined by the type of network and the software used to
transmit data

routing table

generated automatically by software, is used to determine the best possible route for the packet

star topology

usually consists of a central computer (host computer, often a server) and a series of nodes (typically, workstations or
peripheral devices)

static router

requires the network routing manager to give it information about which addresses are on which network

Throughput

similar to bandwidth. It is the amount of data transferred or processed in a specified time, usually one second

Time Division Multiple Access (TDMA)

divides each channel into six time slots. Each user is allocated two slots: one for transmission and one for reception. This
method increases efficiency by 300 percent, as it allows carrying three calls on one channel

Transmission Control Protocol/Internet

an industry-standard suite of communication protocols that enables interoperability

two-tier architecture

(the most common type), a client (tier one) communicates directly with the server (tier two)

wireless network

a network that uses wireless instead of wired technology

Internet, Intranet, Extranet Chapter 7

a project started in 1969 by the U.S. Department of Defense, was the beginning of the Internet.

blog

(short for Weblog) is a journal or newsletter that is updated frequently and intended for the general public. Blogs reflect their
authors' personalities and often include philosophical reflections and opinions on social or political issues.

Directories

are indexes of information based on keywords embedded in documents, which makes it possible for search engines to find
what you are looking for.

Discussion groups

usually for exchanging opinions and ideas on a specific topic, usually of a technical or scholarly nature. Group members post
messages or articles that others in the group can read

Domain Name System (DNS)

When information is transferred from one network to another, domain names are converted to IP addresses by the Domain
Name System (DNS) protocol. Servers using this protocol (called DNS servers) maintain lists of computers' and Web sites'
addresses and their associated IP addresses

extranet

a secure network that uses the Internet and Web technologies to connect intranets of business partners so communication
between organizations or between consumers is possible

gigapop

a local connection point-of-presence that connects a variety of high-performance networks, and its main function is the
exchange of I2 traffic with a specified bandwidth

hypermedia

documents include embedded references to audio, text, images, video, and other documents

hypertext

The embedded references in hypermedia documents are called hypertext; they consist of links users can click to follow a
particular thread (topic).

Hypertext Markup Language (HTML)

the language used to create Web pages. It defines a page's layout and appearance by using tags and attributes. A tag
delineates a section of the page, such as the header or body; an attribute specifies a value, such as a font color, for a page
component

Instant messaging (IM)

a service for communicating with others via a private chat room on the Internet

Internet

a worldwide collection of millions of computers and networks of all sizes. It is a network of networks

Internet backbone

a foundation network linked with fiber-optic cables that can support very high bandwidth. It is made up of many
interconnected government, academic, commercial, and other high-capacity data routers

Internet Relay Chat (IRC)

enables users in chat rooms to exchange text messages with people in other locations in real time

Internet telephony

using the Internet rather than the telephone network to exchange spoken conversations

Internet2 (I2)

a collaborative effort involving more than 200 U.S. universities and corporations to develop advanced Internet technologies
and applications for higher education and academic research

intranet

a network within an organization that uses Internet protocols and technologies (e.g., TCP/IP, which includes File Transfer
Protocol [FTP], SMTP, and others) for collecting, storing, and disseminating useful information that supports business
activities, such as sales, customer service, human resources, and marketing.

Navigational tools

used to travel from Web site to Web sitei.e., surf the Internet

podcast

an electronic audio file, such as an MP3 file, that is posted on the Web for users to download to their mobile devicesiPhones,
iPods, and iPads, for exampleor even their computers

RSS (Really Simple Syndication) feeds

a fast, easy way to distribute Web content in Extensible Markup Language (XML) format. It is a subscription service, and new
content from Web sites you have selected is delivered via a feed reader to one convenient spot

search engine

Google.com or Ask.com, is an information system that enables users to retrieve data from the Web by using search terms

Uniform resource locators (URLs)

also called universal resource locators, identify a Web page. A URL is the address of a document or site on the Internet.

Voice over Internet Protocol (VoIP)

the protocol used for Internet telephony

Web 2.0

the trend toward Web applications that are more interactive than traditional Web applications. Collaboration or e-collaboration
is one of its key components

wiki

a type of Web site that allows users to add, delete, and sometimes modify content.

Ecommerce Chapter 8
advertising model

an extension of traditional advertising media, such as radio and television. Directories such as Yahoo! provide content
(similar to radio and TV) to users for free. By creating more traffic with this free content, they can charge companies for
placing banner ads or leasing spots on their sites.

brokerage model

brings sellers and buyers together on the Web and collects commissions on transactions between these parties

buyer-side marketplace

model, a buyer, or a group of buyers, opens an electronic marketplace and invites sellers to bid on announced products or
make a request for quotation (RFQ). Using this model, buyers can manage the procurement process more efficiently, lower
administrative costs, and implement uniform pricing

Click-and-brick e-commerce

mixes traditional commerce and e-commerce. It capitalizes on the advantages of online interaction with customers yet retains
the benefits of having a physical store location.

E-business

encompasses all the activities a company performs in selling and buying products and services using computers and communication technologies

E-cash

a secure and convenient alternative to bills and coins, complements credit, debit, and charge cards and adds convenience
and control to everyday cash transactions

e-check

the electronic version of a paper check, offers security, speed, and convenience for online transactions

E-commerce

buying and selling goods and services over the Internet

E-procurement

enables employees in an organization to order and receive supplies and services directly from suppliers

E-wallets

available for most handheld devices, offer a secure, convenient, and portable tool for online shopping. They store personal
and financial information, such as credit card numbers, passwords, and PINs

Electronic payment

refers to money or script that is exchanged electronically. It usually involves use of the Internet, other computer networks,
and digitally stored value systems. It includes credit cards, debit cards, charge cards, and smart cards.

horizontal market

concentrates on a specific function or business process and automates this function or process for different industries

informediary model

e-commerce sites collect information on consumers and businesses and then sell this information to other companies for
marketing purposes

merchant model

transfers the old retail model to the e-commerce world by using the medium of the Internet

Micropayments

transactions on the Web involving very small amounts of money. They began as a method for advertisers to pay for cost per
view or cost per click

mixed model

to generating revenue from more than one source

Organizational or intrabusiness ecommerce

involves e-commerce activities that take place inside an organization, typically via the organization's intranet. These activities
can include the exchange of goods, services, or information among employees.

PayPal

a popular online payment system used for many online transactions. Users with valid e-mail addresses can set up accounts
and make secure payments for online transactions using their credit cards or bank accounts.

Search engine optimization (SEO)

a method for improving the volume or quality of traffic to a Web site. A higher ranking in search results should generate more
revenue for a Web site

seller-side marketplace

model occurs most often. In this model, sellers who cater to specialized markets, such as chemicals, electronics, and auto
components, come together to create a common marketplace for buyerssort of a one-stop shopping model

smart card

about the size of a credit card and contains an embedded microprocessor chip for storing important financial and personal
information. The chip can be loaded with information and updated periodically

subscription model

e-commerce sites sell digital products or services to customers

third-party exchange marketplace

model is not controlled by sellers or buyers. Instead, it is controlled by a third party, and the marketplace generates revenue
from the fees charged for matching buyers and sellers

Trading partner agreements

automate negotiating processes and enforce contracts between participating businesses

value chain

a series of activities designed to meet business needs by adding value (or cost) in each phase of the e-commerce process

vertical market

concentrates on a specific industry or market. The utilities industry, the beef and dairy industries, and the sale of medical
products are examples of vertical markets

Voice-based e-commerce

relies on voice recognition and text-to-speech technologies