Download Network Technology and the Internet

Computer Concepts-Illustrated
Introductory, Sixth Edition,
Enhanced
Unit E
Networks and the Internet
1
Objectives
Introduce networks
Classify networks
Understand network topology
Explore network hardware
Explore communications channels
Transport data
Explore wired technology
Explore wireless technology
Computer Concepts, 6th Edition, Enhanced
-- Illustrated
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Objectives
Understand Internet connections
Introduce IP Addresses and Domain
Names
Connect to the Internet using POTS
Connect to the Internet using Cable
Connect to the Internet without Wires
Computer Concepts, 6th Edition, Enhanced
-- Illustrated
3
Communications Network
The combination of hardware, software
and connecting links that transport data
Data is encoded, sent to its destination
then decoded
Noise
Encoded
Data
Source
Decoded
Data
Signal
Communications
Channel
Transmitter
Receiver
Computer Concepts, 6th Edition, Enhanced
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Destination
4
Shared Resources
Networks share hardware,
software, and data
Sharing reduces costs
 Peripheral devices, site licenses
Provides access to Internet
Share data
 Groupware, e-mail, IM, online
conferencing
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Shared Resources (cont.)
Networks are vulnerable
 Unauthorized access
 Malicious code
• Viruses, Trojan horses, worms
Networks are becoming more
standardized
Most benefits outweigh risks
 Computers can be protected
Computer Concepts, 6th Edition, Enhanced
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Network Classifications by
Geographic Coverage
PAN: Personal Area Network (PDAs)
WAN: Wide Area Network (Internet)
NAN: Neighborhood Area Network
(popular with coffee shops)
MAN: Metropolitan Area Network (50
miles)
LAN: Local Area Network (single
building)
Computer Concepts, 6th Edition, Enhanced
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Network Classifications by
Organizational Structure
Client/Server:
 One or more computers configured as
servers and other computers configured
as clients
 Server is central repository for data
Peer-to-Peer (P2P):
 Treats every computer as an equal
 Workstations transfer data to each
other without going through server
 File-sharing networks
Computer Concepts, 6th Edition, Enhanced
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Network Classifications by Organizational
Structure
Computer Concepts, 6th Edition, Enhanced
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Client/Server Terminology
Server: A computer connected to a
network that distributes resources to
network users
Host: Like a server, but mostly used
for Internet services
Workstation: PC connected to a
network
Client: Software that allows access
to server services
Computer Concepts, 6th Edition, Enhanced
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Network Classifications
CATEGORY DESCRIPTION
EXAMPLES
Geographical
Area where network
devices are located
PAN, LAN, WAN, NAN,
MAN
Organizational
Hierarchy of devices
Client/Server, P2P
Physical
Layout and relationship
between devices
Star, bus, ring, mesh, tree
Network
Technologies for cables
and signals that carry
data
Twisted-pair, coaxial, or
fiber-optic cable; RF;
microwaves; Infrared;
power or phone line
Bandwidth
Capacity of network
Broadband, narrowband
Communications Standards for orderly &
protocols
safe data transfer
TCP/IP, SPX/IPX,
NetBEUI/NetBIOS,
AppleTalk
Computer Concepts, 6th Edition, Enhanced
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Network Topology
Physical arrangement of devices,
cables, and wires
Each connection point on a
network is a node:
 Server, workstation, network peripheral,
network device
Physical address: built into circuitry
Logical address: assigned by
network software
Computer Concepts, 6th Edition, Enhanced
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Network Topology
Star
Bus
Ring
– 5 common topologies
–Star (central connection point)
–Ring (connects devices in a circle)
–Bus (common backbone)
–Mesh (each device connected to others)
–Tree (blend of star and bus)
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Interconnecting Networks
Two similar networks can be
connected by a bridge
 Transfers data without regard to format
Gateway
 A device or software used to join dissimilar
networks by making data compatible
Router
 Electronic device that connects 2 or more
networks
Computer Concepts, 6th Edition, Enhanced
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Network Hardware Overview
Computer Concepts, 6th Edition, Enhanced
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Network Hardware
Network Interface Card (NIC)
 Example: Ethernet card
Connection Devices





Modem: converts PC digital signals
Hub: connects nodes on a LAN
Router: decides best way to route data on network
Gateway: entrance to another network
Transceiver: sends and receives data on a wireless
network
 Repeater: amplifies and regenerates signals
Computer Concepts, 6th Edition, Enhanced
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Wired Communication Channels
Twisted-pair cables (phones)
 STP: shielded twisted pair
 UTP: unshielded twisted pair for
small networks
Coaxial cable (television)
 High capacity
Fiber-optic cable
 Pulses of light in thin glass
tubes
 Essential to Internet backbone
Computer Concepts, 6th Edition, Enhanced
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Wireless Communication Channels
RF: radio frequency signals
 Send and receive by a transceiver with
antenna
Microwaves
 More capacity than radio waves
 Need clear path between transmitter and
receiver
 Cannot penetrate metal objects
Computer Concepts, 6th Edition, Enhanced
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Wireless Communication Channels
Satellites
 Signal relayed from ground station
to satellite
 Transponder on satellite receives,
amplifies and retransmits signal
back to earth
 Key technology for Internet
backbone
Computer Concepts, 6th Edition, Enhanced
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Wireless Communication Channels
Infrared light
 Short distance with clear line of sight
 Example: connect notebook with printer
Laser light
 Larger distance with clear line of sight
 Example: between buildings in future
Computer Concepts, 6th Edition, Enhanced
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Bandwidths
The transmission capacity of a
communications channel measured in
bps (bits per second)
Low bandwidth carries less data than
high bandwidth
 Telephone
 Narrowband
High bandwidth
 Coaxial cable
 DSL lines
 Called broadband
Computer Concepts, 6th Edition, Enhanced
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HomePNA and HomePLC
HomePNA
 Uses existing telephone wiring to connect
network devices
 Special NIC and cable to connect computers to
phone jacks
 Can use phone and Internet at the same time
HomePLC
 Uses special NIC and cable to connect
computers to electrical outlets
 Data transmitted as radio waves
 Appliances, radios, and baby monitors affect
signal
Computer Concepts, 6th Edition, Enhanced
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Transporting Data
Protocols: rules for successful and accurate
data transmission
Handshaking: devices communicating with
each other
Packet Switching: determines how data is
broken up
Circuit Switching: establishes a dedicated,
private link between phone lines during a
call
 Inefficient because it reserves a circuit even if
data is not being transmitted
Computer Concepts, 6th Edition, Enhanced
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Communications Protocol
Allows two devices to negotiate
and agree on how data will be
transmitted
TCP/IP




Transport Control Protocol/Internet Protocol
Most common
TCP: breaks data into packets
IP: addresses packets
Computer Concepts, 6th Edition, Enhanced
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Internet Protocols
PROTOCOL
NAME
FUNCTION
TCP/IP
Transmission Control
Protocol/Internet Protocol
Addresses and breaks
messages into packets
HTTP
Hypertext Transfer Protocol
Exchanges information over
the Web
FTP
File Transfer Protocol
Transfers files between
local and remote hosts
POP or
IMAP
Post Office Protocol or
Transfers mail from an eInternet Mail Access Protocol mail server to a client
SMTP
Simple Mail Transfer
Protocol
Transfers mail from a client
to an e-mail server
TELNET
Telecommunications
Network
Allows users to access
multiple hosts
SSL
Secure Sockets Layer
Provides secure data
transfer
Computer Concepts, 6th Edition, Enhanced
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VoIP
Voice over IP or Internet telephony
Uses Internet packets to transmit
voice
You cannot use the same phone line
for voice calls while using your ISP,
but you can use VoIP
Used to play and chat about games
over the Internet
Computer Concepts, 6th Edition, Enhanced
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LAN Standards
Institute of Electrical and
Electronics Engineers (IEEE)
IEEE designation numbers
identify compatible network
technologies
Legacy systems




ARCnet: old, simple, inexpensive
Token Ring: ring topology
FDDI: fiber-optic cables
Ethernet: simultaneous broadcast of
data packets
Computer Concepts, 6th Edition, Enhanced
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Ethernet
Packet accepted only by device
to which it is addressed
Refers to a family of LAN
technologies
 Various transmission rates
 Fiber-optic and twisted-pair cables
 Bus or star topology
Connect many workstations
Computer Concepts, 6th Edition, Enhanced
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Ethernet
CSMA/CD protocol helps avoid collisions
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Home Ethernet Equipment
Ethernet card in each workstation
and peripheral device
Link between network nodes such
as cable
Central connection point (hub)
Uplink port can connect several
hubs
Computer Concepts, 6th Edition, Enhanced
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Wireless Standards
Wi-Fi (Wireless Fidelity)
 Set of wireless networking technologies
 Defined by IEEE 802.11 standards
 Compatible with Ethernet
 No license required
Absence of cables enables
portability
Desirable for notebook and tablet
computers
Computer Concepts, 6th Edition, Enhanced
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Wi-Fi Disadvantages
Speed
 Radio waves
Distance
 25-150 feet
Security
 War driving/LAN-jacking
 Wired Equivalent Privacy: encryption
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Wi-Fi (cont.)
Wi-Fi cards required
 Include transceiver and antenna
 Can be added to notebooks, PCs, and Tablets
 Wireless access point is same as hub or router
in Ethernet
Bluetooth makes short-range wireless
connections between devices such as
a mouse, keyboard, printer
Computer Concepts, 6th Edition, Enhanced
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Internet Connections
The Internet isn’t owned or
operated by corporations or
governments
Traffic exceeds 100 trillion bytes
(terabytes) each week
Backbone provides high-speed
routes for data traffic
 Links and routers maintained by NSPs
(Network Service Providers) like AT&T
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Internet Connections
Users connect to Internet Service
Provider (ISP) or through LAN
ISP provides e-mail and access to
Web
 Handle the physical aspects of
transmitting and receiving data
 Maintain servers for IM, chat groups, FTP
 Installation charges and monthly fees
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Internet Connections
Ping software: Packet Internet Groper
 Checks internet pathways to be sure they are
open and adequate
Traceroute software
 Traces data paths
Modem speed
 Speed is actually a measure of capacity
 Measured in bits per second (bps)
 Most are faster downstream than upstream
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IP Addresses
ISP gives unique IP address to subscriber
Series of numbers in 4 parts
 204.127.129.001
Static IP address: permanent, usually
servers
Dynamic IP address: temporary, for one
session
Look at your Internet configuration settings
to find your IP address
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Domain Names
Translates directly into IP address
Examples: course.com, rutgers.edu
Top-level domain: indicated by extension
ICANN handles domain name registration
and control
edu
com
info
org
mil
gov
int
6th
Computer Concepts,
Edition, Enhanced
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net
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Register a Domain Name
1.
Find out if name is currently
used or reserved
2.
If not available, use a different
top-level domain
3.
Fill out a form online
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Connect to the Internet with POTS
Plain old telephone service
 Dial-up connection via voiceband
modem
 Circuit switching gives continuous
private link
Modem:
 Modulate/demodulate
 Computer sends digital signals,
modems convert to analog
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DSL: Digital Subscriber Line
High-speed and always-on
Digital communication links for
voice and data
Uses standard copper phone
cables
 Fastest and most affordable for individuals
 Variations are ADSL, SDSL, HDSL AND
DSL lite
 1.5 Mbps downstream
Computer Concepts, 6th Edition, Enhanced
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ISDN: Integrated Services Digital
Network
All-digital, carries voice and data
Mostly used for business LANs
Faster than dial-up, slower than
DSL or cable
T1, T3, or T4
Used by businesses and ISPs on
dedicated leased lines
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Cable Internet Connections
Satellite dish “farm” or head-end
 Where TV broadcasts are received and
retransmitted for cable connections
Bandwidth provides signals for
TV, incoming and outgoing data
You need
 Ethernet card
 Cable modem: usually ISP provides
 Splitter to connect both modem and TV
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Cable Internet Connections (cont.)
Bandwidth issues
 Could slow down as more neighbors use
service
Security issues
 DOCSIS-compliant cable modems
• Filters packets to certain ports
• Secures your computer from your neighbors
• Doesn’t close up all security holes associated
with always-on connections
Computer Concepts, 6th Edition, Enhanced
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Security When Always-On
Same IP address when
on – hackers can use
High-speed access
desirable for hackers
Turn off machine often
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Wireless Internet Connections
DSS: Direct Satellite Service
 Dishes are owned/leased by individuals
 Can be blocked by adverse weather
 Subject to latency delays
Fixed wireless
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Broadcasts RF data signals over large areas
Used by homes and businesses
Less latency than DSS
Ethernet-compatible, a large Wi-Fi
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Wireless Internet Connections
Public Wi-Fi
 Range of coverage: hotspot
 Open to public: free, subscription, fees
WAP (wireless access protocol)
 Handheld devices
Cellular-ready modems
 PC cards for notebooks or tablets
 Transfers data using cell phone service
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Connect to the Internet with Handheld
Devices
Screen size and color
Keyboard functionality
Network connection options
Band depends on where you will
use it (tri-band for Europe)
Features such as SMS, MMS,
cameras
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TechTalk: Installing a LAN
Install Ethernet NIC
 On motherboard or with PC card; both have port
for network cable
Attach cable to NIC port and hub port
Turn on PC
Windows should automatically detect
and establish connection
Can activate file sharing and drive
mapping by using Windows Network
Neighborhood
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Context: Education
Categories


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CBT (computer-based training)
CAL (computer-aided learning)
CAI (computer-aided instruction)
Simulations
99% of American public schools have computers
 Not all students have daily access
Some colleges require incoming students to have a
computer
DE/DL (Distance Education/Learning)
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Issue: Free Wi-Fi?
Free WLANs
No license to set up a Wi-Fi
Can reduce bandwidth for paying
customers
Are they legal?
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Unit Summary
Networks offer shared resources
Networks classified by:
 Geography
 Topology
 Organizational structure
 Links
 Bandwidth
 Protocols
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Networks and the Internet
End
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