Transcript Computer Concepts-Illustrated Introductory, Sixth Edition

Computer Concepts – Illustrated
Introductory, Seventh Edition
UNIT E:
Networks and the Internet
Objectives
Introduce networks
Classify networks
Explore network hardware
Explore data transport
Compare wireless and wired
technology
Install a LAN
Computer Concepts – Illustrated Introductory, Seventh Edition
Objectives
Share network resources
Introduce Internet technology
Explore IP addresses and domain
names
Connect to the Internet with wires
Connect to the Internet without
wires
Computer Concepts – Illustrated Introductory, Seventh Edition
Objectives
Talking points: Why pay for
Internet access if you can get it
for free?
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Communications network combination of hardware,
software, and connecting links
that transport data
Allow users to share resources –
hardware, software, and data
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Ethernet
Significant network idea conceived
by Bob Metcalfe in 1976
Transfers data between computers
Key element in nearly every
computer network
• Including Internet
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Computer is on network if:
 computer can access other computers
or share hardware with other computers
Networks in home
 Access surveillance and monitoring
devices
 Control media devices
 Share hardware and software
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Sharing networked hardware
 Reduce costs
 Expand access
Sharing networked software
 Reduce costs
 Facilitate data sharing
 Enable collaboration
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Disadvantages of network
connection
 Vulnerability to unauthorized access
 Susceptibility to malicious code
Most computer owners believe
that advantages far outweigh
disadvantages
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Network is like spider web with many
interconnecting points
 Node - each connection point
• Network nodes typically contain computers,
networked peripherals, or network devices
Server
 Computer connected to network that
distributes resources to network users
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Networks
Network connects computers and
peripherals
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Networks - classified according to
size and geographic structure
 PAN (personal area network)
 LAN (local area network)
 NAN (neighborhood area network)
 MAN (metropolitan area network)
 WAN (wide area network)
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Networks Technologies
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Client / server network
 Must have at least one server and one
or more clients
 Network computers can serve as clients
or servers
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Server
 Computer that provides services to other
computers the network (clients)
Application server
 Runs application software for network
workstations
File server
 Stores files and supplies them to workstations
on request
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Print server
 Handles jobs sent to network printers
Workstation
 Network client, usually personal
computer
Computer Concepts – Illustrated Introductory, Seventh Edition
Classifying Networks
Peer-to-peer structure
 Does not have a server
 Workstations serve as both clients and
servers
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Network device
 Any electronic device that broadcasts
network data, boosts signals, or routes
data to destination
 Modems, network interface cards, hubs,
switches, routers, gateways, bridges,
repeaters
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Modem
 Converts digital signals into signals that
can travel over network
Network interface card (NIC)
 Network circuitry needed to connect to
network
Ethernet card (Ethernet adapter)
 NIC designed to support Ethernet
protocols
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
If computer does not have
Ethernet adapter,can purchased
and installed
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
USB and PC Ethernet adapters plug into
ports on outside of system unit
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Network hub
 Links two or more nodes of wired network
Network switch
 Sends data only to network devices specified
as destination
Network router
 Transmits data from one network to another
 Used to connect LANs and WANs
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Network Router
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Special hardware for wireless networks
 Transceiver
• Used to send and receive wireless data
 MIMO (multiple-input multiple-output)
technology
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Network Hardware
Networked peripheral
Any device with built-in network
circuitry
Can connect directly to network
Network attached storage (NAS)
Storage device that directly
connects to network
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Communications channel (network
link) - physical path or frequency for
signal transmission
 Used for transporting data
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Wired network
 Data travels from one device to another
over cables
Wireless network
 Data travels through air, no need for
cables
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Types of cables
 Twisted pair
 Shielded twisted pair (STP)
 Coaxial (coax)
 Fiber-optic
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Buying cable - choose Category
5 (Cat 5) or Category 6 (Cat 6)
 Rating indicates capacity
 Higher number, higher capacity
Cables can be purchased in
variety of lengths
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Ethernet network cables
terminated at each end with RJ45
connector
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Bandwidth
 Transmission capacity of communications
channel
• High-bandwidth systems include cable and
DSL (broadband)
• Systems with less capacity include dial-up,
referred (narrowband)
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring Data Transport
Other cables can be used to transport
data over wired network
 USB, serial, parallel, SCSI, and FireWire
Wireless networks transport data via
 RF (radio frequency) signals
 Microwaves
 Infrared lights
Computer Concepts – Illustrated Introductory, Seventh Edition
Comparing Wireless and
Wired Technology
Wired networks
 Fast, secure, reliable, simple to
configure
Wireless
 Provide mobility
 No unsightly wires or cables to tangle
 No need to run wires through walls,
ceilings, floors
Computer Concepts – Illustrated Introductory, Seventh Edition
Comparing Wireless and
Wired Technology
Wired network is best choice if
you need speed
Wired networks more secure than
wireless networks
 Wireless signals pass through air and
can be intercepted more easily
Computer Concepts – Illustrated Introductory, Seventh Edition
Comparing Wireless and
Wired Technology
Range limits
 Wired network - defined by longest
cable in configuration
 Wireless network - depends on type of
signal, transmitter strength, and physical
environment
Signal strength
of wireless
network
Computer Concepts – Illustrated Introductory, Seventh Edition
Comparing Wireless and
Wired Technology
Prices have equalized between
wired and wireless networks
 May need some additional equipment
for wireless
• Wi-Fi card
• Wireless access point
or router
Computer Concepts – Illustrated Introductory, Seventh Edition
Installing a LAN
Place router in central location,
plug into surge protected outlet
Run cables from router to
Ethernet adapter in each workstation
Run cable from Internet device
and router’s WAN port
Turn on devices, computer
should recognize and
establish connection
Computer Concepts – Illustrated Introductory, Seventh Edition
Installing a LAN
Before using network, adjust
router configuration settings
Computer Concepts – Illustrated Introductory, Seventh Edition
Installing a LAN
Other ways to set up wired
network
 HomePNA network uses telephone wiring in home
 Power-line network uses existing electrical wiring
Computer Concepts – Illustrated Introductory, Seventh Edition
Installing a LAN
Power-line networks form
infrastructure of LAN using existing
electrical wiring
 Special NIC to connect computer to standard
electrical outlet
Computer Concepts – Illustrated Introductory, Seventh Edition
Sharing Network Resources
Wireless and wired devices can
be connected to same network
 Most wireless routers include ports for
Ethernet cables and WAN port for cable
to Internet device
Computer Concepts – Illustrated Introductory, Seventh Edition
Sharing Network Resources
Access network by clicking
workgroup name
 May also have to enter password and
user ID
SSID (service set identifier)
 Helps log into correct network in places
where networks may overlap
Computer Concepts – Illustrated Introductory, Seventh Edition
Sharing Network Resources
To add workstations
 Turn on computer with wireless
capabilities
 Choose correct network
 Enter network key or passphrase
Workstation owners can specify
whether files and locally attached
printers can be accessed from
other workstations on network
Computer Concepts – Illustrated Introductory, Seventh Edition
Sharing Network Resources
File Sharing
Computer Concepts – Illustrated Introductory, Seventh Edition
Sharing Network Resources
Three ways to connect printer to
network using Windows Control Panel
 Connect it to one workstation in network
 Network print server
 Connect printer directly to hub or router
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Internet backbone
 Consists of high-speed fiber-optic cables
connecting high-capacity routers that
direct network traffic
 Provide main high-speed routes for data
traffic
 Network service providers (NSP) maintain
backbone links and routers
 NSP equipment and links are tied together
by network access points (NAPs)
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Connecting computer to Internet
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
ISP equipment offers variety of services
 e-mail, chat groups, IM capabilities, music file sharing,
FTP, and more
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Upstream speed
 Rate of data transmitted from computer
to Internet
Downstream speed
 Rate of data arriving at computer
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Internet uses variety of
communications protocols
Support basic data transport and
services
• TCP
– Breaks message or file into packets
• IP
– Addresses packets so they can be routed
to destinations
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Main Protocols used on Internet
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
PING (Packet Internet Groper)
Sends signal to specific Internet
address
Waits for reply
Reports elapsed time between
sending and receiving signal
Traceroute
Records packet’s path from your
computer to destination
Computer Concepts – Illustrated Introductory, Seventh Edition
Introducing Internet Technology
Connection options
Fixed Internet access - links to ISP
from stationary point
Portable Internet access - allows
easy movement of access device
Mobile Internet access – allows
Internet use on the go
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring IP Addresses and
Domain Names
IP address - Series of numbers
 204.127.129.001
 Each section called ‘octet’
 Each address requires 32 bits
 Four sections create classes of IP addresses
• Based on size, type of network, other functions
 ICANN (Internet Corporation for Assigned
Names and Numbers)
• Coordinates allocation of IP addresses, and
more
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring IP Addresses and
Domain Names
IP addresses - assigned by ISPs
or network or system managers
IP addresses can also be
obtained through DHCP
(Dynamic Host Configuration
Protocol)
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring IP Addresses and
Domain Names
Dynamic IP addresses
 Temporary address
 Generally assigned to computers running
client software for accessing Web, email,
listening to Internet radio, chat groups
Static IP address
 Permanent address
 Assigned to ISPs, Web sites, Web hosting
services, email servers
Computer Concepts – Illustrated Introductory, Seventh Edition
Exploring IP Addresses and
Domain Names
Domain name
 Corresponds to unique IP address
entered into database called Domain
Name System
 Domain name server –
any computer that
hosts this database
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
Dial-up
connection
POTS (plain
old telephone
service) is
used to
transfer data
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
Voiceband modem
 Converts digital signals from computer
into analog signals for telephone lines
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
ISDN (Integrated Services Digital
Network)
 Fixed Internet connection moves data
over ordinary telephone lines
 Use telephone wall jack as fixed point
of connection
 Connect computer to ISDN terminal
adapter which sends digital signals
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
DSL (digital subscriber line)
 High-speed, digital, always-on Internet access
 Uses standard phone lines to transport data
 Requires modem and filters
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
Dedicated line
 T1, T3, and T4 services - high-capacity
dedicated lines can be leased from
telephone company
 Not used by other customers
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
Cable connection
 Provides always-on broadband Internet
access over same infrastructure that
offers cable television services
 Bandwidth is divided to offer both
television and Internet access
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
with Wires
Connecting to Internet via cable TV
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
Satellite Internet service
 Means of distributing always-on, highspeed, asymmetric Internet access
 Broadcasting signals to and from
personal satellite dish
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
Fixed wireless Internet service
(wireless broadband)
 Internet access to homes and
businesses by broadcasting data signals
over areas large enough to cover most
cities and outlying areas
 WiMAX (Worldwide
Interoperability for
Microwave Access) –
well-known fixed wireless
standard
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
Public Wi-Fi network
 Wireless LAN that provides open access
to public
 In many public places such as
bookstores, coffee shops, airports,
hotels, and restaurants
Wi-Fi hotspot
 Range of Wi-Fi network’s coverage
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
Mobile WiMAX
 Designed to offer Internet access with
seamless handoff from coverage area of
one tower to another
Portable satellite Internet service
- available for those who need
access when traveling in remote
locations
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
WAP (Wireless Access Protocol)
 Communications protocol providing
wireless Internet access from handheld
devices
Computer Concepts – Illustrated Introductory, Seventh Edition
Connecting to the Internet
without Wires
Mobile broadband
 Allows access to full
spectrum of Internet
via handheld device
 Requires fast
connection, data
service subscription,
and mobile broadband
equipment
Computer Concepts – Illustrated Introductory, Seventh Edition
Talking Points:
Why pay for Internet access if you can get it for free?
Free wireless LANs (WLAN)
 Found in airports, hotels, coffee shops
 Sometimes offered by rogue WLAN
operators who buy service, then
distribute connections over wireless
LANs to friends, neighbors, and anyone
who passes by
But is this free access always
legal?
Computer Concepts – Illustrated Introductory, Seventh Edition
Talking Points:
Why pay for Internet access if you can get it for free?
Problems include
 Piggyback use
 Data security
Providers feel every person using free
Wi-Fi is one fewer customer
Wisdom of unregulated network
availability is questioned by resulting
ethical, security, and privacy issues
Computer Concepts – Illustrated Introductory, Seventh Edition