CHAPTER 7
Internet – A network of networks, which communicates using TCP/IP (Transmission
Control Protocol/Internet Protocol)
 World Wide Web – A system of interlinked (hyperlinked) documents accessible by
use of HTTP (HyperText Transfer Protocol)
 Protocol – Convention or standard that controls and enables communication between
two computers
o Rules governing the syntax, semantics, and synchronization of communication
Networking and Communication Trends
 Convergence
o Telephone networks and computer networks converging into a single digital
network using Internet-based standards
o Cable companies now offer voice services
 Broadband – High-speed transmission technology; designates a single
communications medium that can transmit multiple channels of data simultaneously
 Broadband Wireless
o Voice and data communication and Internet access are increasingly taking
place over broadband wireless platforms, such as cell phones and handheld
digital devices
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Components of a Simple Network
 Two or more connected computers
 Network Interface Card (NIC) – Expansion card inserted into a computer to enable it
to connect to a network
 Network Operating System (NOS) – Routes and manages communications on the
network and coordinate network resources
 Server Computer – Performs important network functions for client computers
 Hubs – Simple devices that connect network components, sending a packet of data to
all other connected devices
 Switch – Can filter and forward data to a specified destination on the network
 Router – Communications processor used to route packets of data through different
networks, ensuring that the data sent gets to the right address
Telecommunications and Networking in Today’s Business World
 Key Digital Network Technologies:
o Client/Server Computing
 A distributed processing model in which some processing power is
located within small, inexpensive client computers
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The clients are linked to one another through a network that is
controlled by a network server computer
 The server sets the rules of communication for the network and
provides every client with an address so others can find it on the
network
o Packet Switching
 Messages are first broken down into small bundles of data called
packets
 Packets are sent along different communication paths as paths become
available
 Packets are reassembled once they reach their destinations
o TCP/IP and Connectivity
 TCP (Transmission Control Protocol)
• Breaks information into small chucks called data packets
• Manages the transfer of the packets from computer to computer
• Reassembles data packets into a message at the destination
 IP (Internet Protocol)
• Controls how data packets are formed
• Addresses each packet with the source and destination address
• A data packet conforming to the IP spec is called an IP
datagram
Communication Networks and Transmission Media
 Computers use digital signals (a binary waveform) to communicate a message while a
telephone system uses an analog signal (continuous waveform)
o To use analog telephone system to send digital data, must use device called
modem
 Modem – Modulator-demodulator
o Translates digital signals from a computer into analog form to be transferred
over analog telephone lines
o Translates analog signals back into digital form for the receiving computer
 Types of Networks
o Local Area Network (LAN)
o Campus Area Network (CAN)
o Metropolitan Area Network (MAN)
o Wide Area Network (WAN)
 Transmission Media – Wired
o Twisted Pair (TP) – Two or more pairs of insulated copper wires twisted
together and may be shielded (STP) or unshielded (UTP). It is the lowest
capacity of the cable options
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Coaxial (COAX) – Contains a solid inner copper conductor surrounded by
insulation and outer braided copper or foil shield. It has higher capacity than
the twisted pair
o Fiber-Optic – Made of light-conducting glass or plastic core, surrounded by
more glass, called cladding, and a tough outer sheath. It is high capacity and
used in high speed backbones
o
The Wireless Revolution
 Wireless computer networks and Internet access
o Bluetooth, Wi-Fi, WiMax, Broadband cellular wireless services
 Cellular Phone – A two-way wireless communication that assigns unique frequencies
to calls and can transmit in analog or digital
Internet Access
 Telephone or Dial-Up Connection
o Telephone Modem – A device that connects your computer to your phone line
so that you can access another computer or network
 Modulates analog carrier signal to encode digital information
 Demodulates carrier signal to decode transmitted information
 Digital Subscriber Line (DSL)
o A high-speed internet connection using phone lines, which allows you to use
your phone for voice communications at the same time
o Need to be close to the phone company to get a good connection speed
 Cable Modem
o A device that uses your TV cable to deliver an Internet connection
o More computers on the network ,the slower the transmission rate
 Internet Over
o Satellite Modem – A modem that allows you to get Internet access from a
satellite dish
o Download using the satellite modem, but upload usually using phone
 Wireless
o Fixed wireless access points allow computers with access cards to access
ground-based networks
o Mobile wireless devices can access networks using mobile wireless networks
The Internet
 Internet Addressing and Architecture
o Every device connected to the internet has a unique 32-bit numeric IP address
o A Domain Name System (DNS) converts IP addresses to English-like domain
names
 The domain name system is a hierarchical system with a root domain, top-level
domains, second-level domains, and host computers at the third level
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Internet Architecture
o Internet backbone connects to regional networks, which in turn provide access
to Internet service providers, large firms, and government institutions
o Network Access Points (NAP) and metropolitan area exchanges (MAE) are
hubs where the backbone intersects regional and local networks and where the
backbone owners connect with one another
Internet Services and Communication Tools
o E-mail
o Usenet newsgroups – discussion groups on electronic boards
o Chatting and instant messaging
o Voice over IP – delivers voice in digital form over the internet
o Unified communications – integrates all communications into one stream to
allow user to switch back and forth
o Virtual Private Networks (VPN) – a secure, encrypted private network for use
internally to an organization
Intranets and Extranets
o Intranet – An internal organizational network that provides access to data
across the enterprise; protected from public visits by firewalls
o Extranet – Authorized visitors are given limited access to an internal intranet
Client/Server Computing on the Internet
o Client computers running web browser and other software can access an array
of services on servers over the Internet
o These services may all run on a single server or on multiple specialized
servers
VoIP
Digitizes and breaks up a voice message into data packets that may travel
along different routes before being reassembled at the final destination
o 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
VPN
o A private network of computers linked using a secure “tunnel” connection
over the Internet
o Protects data transmitted over the public internet by encoding the data and
‘wrapping” them with the IP
o By addressing 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
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HTTP – Communications standard used for transferring web pages
o Uniform Resource Locators (URL) – Addresses of web pages
o Web Servers – Software for locating and managing web pages
Searching for Information on the Web
o Search Engines
 Started in early 1990s as relatively simple software programs using
keyword indexes
 Today, major source of Internet advertising revenue via search engine
marketing, using complex algorithms and page ranking techniques to
locate results
o Shopping Bots
 Uses intelligent agent software for searching internet for shopping
information
How Google works:
o The user enters query
o Google’s Web servers receive the request and Google uses PCs linked together
and connected to the Internet to handle incoming requests and produce the
results
o Request is sent to Google’s index servers that describe which pages contain
the keywords matching the query and where those pages are stored on the
document servers
o Using the PageRank software, the system measures the importance or
popularity of each page by solving a complex equations
o Small text summaries are prepared for each Web page
o Results are delivered to the user
o
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Emerging Internet Technologies and Issues
 Web 2.0
o Blogs, wikis, RSS, mash-ups, social software
 Web 3.0 – The future web
o Semantic web
 The Future Internet: IPv6 and Internet 2
o IPv6 – Allows 128 bit addresses, a quadrillion possible addresses
o Internet2 – Consortia of agencies working to provide a new robust and highbandwidth version of the Internet
o CA*net4 infrastructure
 Based on optical networking technologies to promote the fastest
speeds available over the Internet
Radio Frequency Identification (RFID)
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Uses tiny tags with embedded microchips containing data about an item and location,
and antenna
Tags transmit radio signals over short distances to special RFID readers, which send
data over network to computer for processing
Active RFID – Tags have batteries, data can be written, range is hundreds of feet,
more expensive
Passive RFID – Range is shorter, smaller, less expensive, powered by radio frequency
energy
How it works:
o A microchip holds data including an identification number, the rest of the tag
is an antenna that transmits data to a reader
o The RFID reader has an antenna that constantly transmits. When it senses a
tag, it wakes it up, interrogates it, and decodes the data. Then it transmits the
data to a host system over wired or wireless connections
o The host computer processes the data from the tag that have been transmitted
by the reader
Wireless Sensor Networks
 Networks of hundreds of thousands or thousands of interconnected wireless devices
embedded into physical environment to provide measurements of many points over
large spaces
 Used to monitor building security, detect hazardous substances in air, monitor
environmental changes, traffic, or military activity
 Devices have build-in processing, storage, and radio frequency sensors and antennas
 Require low-power, long-lasting batteries and ability to endure in the field without
maintenance
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