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Chapter5:1:
4:Internet
File Management,
Computer,
Virus
Chapter
andInternet,
LAN Technology
Protection,
Web,
and E-Mail
and Backup
Basics
1
Chapter 5 Preview
After this chapter, you should be able to:
– Describe the characteristics of various networks
– Diagram Shannon’s model of a communications
network
– List types of cables
– List network devices
– Describe the role of communications protocols and list
some protocols associated with the Internet and LANs
– Explain packet switching and circuit switching
– Explain packet switching and circuit switching
– Recount the history of the Internet
Chapter 5: Internet and LAN Technology
2
Chapter 5 Preview
After this chapter, you should be able to:
– Draw a conceptual diagram illustrating the Internet
backbone, NAPs, NSPs, routers, and ISPs
– Explain Ping and Traceroute
– Explain the differences between permanent IP
addresses, dynamic IP addresses, private IP
addresses, and domain names
– Describe the advantages and disadvantages of dial-up,
cable modem, DSL, ISDN, T1, T2, and wireless
Internet access
– Explain when and why it is important to implement
security measures such as antivirus software, firewalls,
and Network Address Translation
Chapter 5: Internet and LAN Technology
3
Chapter 5 Outline
• Section A
– Network Building Blocks
• Section B
– Local Area Networks
• Section C
– Internet Technology
• Section D
– Internet Access
Chapter 5: Internet and LAN Technology
4
Chapter 5
Internet and LAN Technology
Section A: Network Building Blocks
Computer Concepts 8th Edition
Parsons/Oja
Why is networking
computers advantageous?
• Reduce costs
• Provides access to a wide range of
services and specialized peripheral
devices
• Sharing data on a network is easy
• Networks enable people to work
together regardless of time and place
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Do networks have
disadvantages?
• Primary disadvantage is their
vulnerability to unauthorized access
• More vulnerable than standalone
computers to malicious code
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How are networks classified?
•
•
•
•
•
•
Geographical scope
Organizational structure
Physical topology
Network links
Bandwidth
Communications protocols
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Why is geographic scope
important?
•
•
•
•
•
Wide Area Network
Metropolitan Area Network
Local Area Network
Neighborhood Area Network
Personal Area Network
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What is the difference between a
client/server network and a peerto-peer network?
• Client/server – contains
servers and clients
• Peer-to-peer (P2P) –
every computer is
considered an equal
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How are devices on a
network physically arranged?
Star Topology
Tree Topology
Ring Topology
Mesh Topology
Chapter 5: Internet and LAN Technology
Bus Topology
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11
Network Links: What
connects the nodes of a
network?
• Data can travel from one network device to
another over a cable or through the air
• A communications channel is a physical
path or a frequency for a signal transmission
• Wired network
– Networks use different types of cables
• Wireless network
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What are popular network
cabling options?
• Today’s networks use twisted-pair
cables
– UTP (unshielded twisted pair)
– STP (shielded twisted pair)
– Looks similar to telephone cable
– Has square plastic RJ-45 connector
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What are popular network
cabling options?
• Another option is coaxial cable
– Resembles cable-TV cable
– Round, silver BNC or F-type connector
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What are popular network
cabling options?
• Fiber-optic cable is a bundle of extremely thin
strands of glass
– Each optical fiber (strand) is thinner than a
human hair
• USB, serial, parallel, SCSI, and Firewire
connections
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What are the options for
wireless networks?
• Data can also travel airways in form of RF signals sent
and received by a transceiver
• Microwaves provide another option for transporting
data
• Radio and microwave transmissions cannot be bent
around the surface of the earth to reach far-flung
towers
• Communications satellites play an important part in
long-distance communications
• A transponder on the satellite receives the signal,
amplifies it, and retransmits the signal back to a
ground station on earth
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What’s the difference between
analog and digital signals?
• Digital signals are transmitted as bits
using a limited set of frequencies
• Analog signals can assume any value
within a specified range of frequencies
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What’s bandwidth?
• The transmission capacity of a
communications channel
• High-bandwidth communications
systems are sometimes referred to as
broadband
• Systems with less capacity are referred
to as narrowband
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How does data travel over a
network?
• In 1948, Claude Shannon published an
article that described a communication
model
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How does data travel over a
network?
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What is a protocol?
• A set of rules for efficiently transmitting
data from one network node to another
• The best-known protocol is probably
TCP/IP
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What’s a packet?
• When you transmit data, it is broken up into
small pieces called packets
• A packet is a parcel of data that is sent
across a network
– Has the address of its sender
– Has the address of the destination
– Has some data
• When they reach the destination, they are
put back together into original form
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How does a protocol initiate
a transmission?
• A synchronous protocol coordinates
sending and receiving by using a clock
signal
• Asynchronous protocols require the
transmitting computer to send a start bit
that indicates the beginning of a packet
– Handshaking
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How do protocols regulate
the flow of data?
• Simplex – signal travels in only one
direction
• Half duplex – signal travels in both
directions, but only one direction at a
time
• Full duplex – signal travels in both
directions at the same time
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Chapter 5
Internet and LAN Technology
Section B: Local Area Networks
Computer Concepts 8th Edition
Parsons/Oja
LAN Standards: What are
LAN standards?
• LAN technologies are standardized by
the Institute of Electrical and Electronics
Engineers
• IEEE designation numbers help identify
compatible network technologies
– IEEE 802.3
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What is ARCnet?
• One of the oldest, simplest, and least
expensive LAN technologies
• Original ARCnet standard supported
transmission rates of 2.5 Mbps
• Later versions supported 20 and 100
Mbps transmission rates
• Permits mixed transmission media
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What is Token Ring technology?
• Defined by the IEEE
802.5 standard
• Passes data around a
ring topology using a
signal called a “token”
to control the flow of
data
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What is the FDDI standard?
• Offers 100 Mbps
speeds over fiberoptic cables
• Popular campus
network technology
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How does Ethernet work?
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How does Ethernet work?
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How fast is an Ethernet
network?
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What equipment is required
for Ethernet installations?
• An Ethernet card is a type of network
interface card designed to support
Ethernet protocols
• A hub is used to connect more than two
computers
– Each network device requires one of
the hub ports
– You can add hubs using an uplink
port
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What equipment is required
for Ethernet installations?
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What is Wi-Fi?
• Wireless LANs are slower but eliminate unsightly
wires
• Signals can be disrupted by large metal objects,
cell phones, pagers, and other wireless devices
• Most popular is 802.11 sometimes called WiFi for
“wireless fidelity”
– Range of up to 150 feet
• Bluetooth
– 1 Mbps, range of 30 feet
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HomePNA and HomePNC
Networks
• HomePNA uses a special NIC and
cable to connect each computer to a
standard telephone wall jack
• Network frequency is usually different
from voice
• HomePLC uses special NIC to
connect to standard electrical outlet
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HomePNA and HomePNC
Networks
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LAN Installation: How do I
set up a simple LAN?
• First make sure every PC contains an Ethernet
port
• Next, attach each workstation to a hub
• With all workstations connected, turn them on
• Windows should automatically detect the
Ethernet cards and establish a connection to the
network
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How do I set up a simple
LAN?
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How do I access network
resources?
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How do I specify which
resources can be shared by
other workstations?
• Each workstation can specify whether
its files will be accessible to other
workstations on the network
• Drive mapping is Windows terminology
for assigning a drive letter to a storage
device that’s located on a different
workstation
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Chapter 5
Internet and LAN Technology
Section C: Internet Technology
Computer Concepts 8th Edition
Parsons/Oja
Background: How did the
Internet get started?
• The United States created ARPA (Advanced
Research Projects Agency).
– To help scientists communicate and share
valuable computer resources
– In response to the Soviet Union’s launch of
Sputnik in 1957, the first artificial satellite
• The ARPANET, created in 1969, connected
computers at four universities
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How is the Internet
structured?
NAP
NAP
Links maintained by AT&T
Links maintained by Sprint
High-speed AT&T routers
High-speed Sprint routers
To ISP
Chapter 5: Internet and LAN Technology
To ISP
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Is it possible to track data as
it travels over the Internet?
• Using Ping or Traceroute, you can
discover how long data is in transit
• On average, data within the US usually
arrives at its destination 110-120 ms
(milliseconds) after it is sent
• Overseas transmissions require a little
more time
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Is it possible to track data as
it travels over the Internet?
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What kinds of network
devices are part of an ISP?
• An ISP operates network devices that
handle the physical aspects of
transmitting and receiving data from
your computer
• Many ISPs operate e-mail servers to
handle incoming and outgoing mail for
their subscribers and Web servers for
subscriber Web sites
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What kinds of network
devices are part of an ISP?
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Internet Protocols: Why does
the Internet use TCP/IP?
• Provides a standard that is fairly easy to
implement, public, free, and extensible
• The Internet is not owned, operated, or
controlled by any single entity
• TCP/IP is glue that holds the Internet
together
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Is TCP/IP the only Internet
Protocol?
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IP Addresses: Does the
Internet use a special
addressing scheme?
• The IP part of TCP/IP defines the format for the
addresses that identify computers on the Internet
• These addresses are called IP addresses
• An IP address is a series of numbers, such as
204.127.129.001
– It is separated into four sections by periods
– Each section’s number cannot exceed 255
– Each address requires 32 bits (8 bits per
section)
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Do I need a permanent IP
address?
• Static IP address – permanently
assigned IP address
• Dynamic IP address – temporarily
assigned
• ISPs need static IP addresses
• Clients typically use dynamic IP
addresses as the IP addressing scheme
provides approximately only 4.3 billion
unique addresses
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Domain Names: What’s a
domain name?
• People find it difficult to remember long strings
of numbers, so host computers also have
names called domain names
• Domain name – “fully qualified domain name”
(FQDN), usually typed in all lowercase
– Key component of URLs and e-mail
addresses
– www. msu.edu/infotech - www.msu.edu is
the domain name
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Domain Names: What’s a
domain name?
• Top-level Domains:
–
–
–
–
–
–
–
–
–
biz
com
edu
gov
info
int
mil
net
org
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How are domain names
related to IP addresses?
• Each name corresponds to an IP address
• Domain name system – Huge database
that houses the names and IP addresses
• Domain name servers – Computers that
house the database
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How do I get a domain name?
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Is a fee required to obtain a
domain name?
• You can register a domain name for a
minimal annual fee ($10 - $50)
• Some Internet entrepreneurs have
registered high-profile domain names
and resell them
– team.com - $250,000
– science.tv - $100,000
Chapter 5: Internet and LAN Technology
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Chapter 5
Internet and LAN Technology
Section D: Internet Access
Computer Concepts 8th Edition
Parsons/Oja
How does a dial-up
connection work?
• While connected to your ISP, your call is
routed through the telephone
company’s local switch to the ISP
Local
Switch
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How does a modem work?
• Modem – derived from modulate and
demodulate
• Modulation – changing characteristics
of a signal (digital to analog)
• Demodulation – changing signal back
to original state (analog to digital)
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How fast is a modem?
•
•
•
•
Speed was measured as baud rate
Today, measure in terms of bits per second
V.90 – theoretical maximum speed of 56 Kbps
Even with perfect connection, a 56 Kbps
modem tops out at about 44 Kbps
• Slightly faster speeds may be available with
the new V.92 and V.44 modem standards
• Downstream vs. upstream
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Cable Television Connections:
How does a cable modem work?
• Community antenna television – CATV
• The satellite dish farm at which television
broadcasts are received and retransmitted is
referred to as the head-end
• From the head-end, cabling system branches
out and eventually reaches consumers’
homes
• Topology is similar to computer network
Chapter 5: Internet and LAN Technology
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How can the cable TV
system provide Internet
access?
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Are television and data
signals carried over the same
cable?
• Lowest-capacity coaxial cable has far
greater capacity than POTS lines
• Cable’s bandwidth is divided among 3
activities
Chapter 5: Internet and LAN Technology
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How do I set up a cable
modem connection?
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How do I set up a cable
modem connection?
• An always-on connection is always
connected
• A hacker who discovers that your
computer has a security weakness can
easily find it again, and its high-speed
access makes it a very desirable target
Chapter 5: Internet and LAN Technology
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What’s the significance of
becoming part of a
“neighborhood network”?
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DSL, ISDN, T1, and T3: What
other options are available for
high-speed Internet access?
• Several services such as DSL, ISDN,
T1, and T3 take advantage of full
capacity of the telephone connections
• Offers high-speed digital
communications links for voice and data
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What is DSL?
• DSL (Digital Subscriber Line) is a highspeed, always-on, Internet access
technology that runs over standard phone
lines
• Several versions exist – ADSL, SDSL, HDSL
• xDSL – refers to entire group of DSL
technologies
• DSLAM (DSL Access Multiplexor) – interpret
data signals
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Who uses T1 or T3 service?
• T1 – high-speed 1.544 Mbps digital network
– Consists of 24 individual channels (64 Kbps for
each)
– Popular for businesses and ISPs
• T3
– 672 channels
– Supports data rates of about 43 Mbps
– Sometimes referred to as DS3 (Digital Service-3)
lines
– Provide many of the links on the Internet
backbone
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How does satellite access
work?
• Direct satellite service (DSS) uses a
geosynchronous or low-earth satellite
to send television, voice, or computer
data directly to a satellite dish
• Two-way satellite service ships both
upstream and downstream data
through the satellite
– Offers 500 Kbps downstream
– 40-60 Kbps upstream
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How does satellite access
work?
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Mobile Internet Access
• You can use a mobile Internet connection to
surf the Web and check your e-mail
• A Wi-Fi hotspot is wireless broadband
Internet service offered in public locations
– WISPs maintain Wi-Fi hotspots
• WAP (Wireless Access Protocol) is a
communications protocol that provides
Internet access from handheld devices
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What kind of services are
available from handheld devices?
•
•
•
•
•
•
•
Short message service
Multimedia messaging
Music fingerprinting
Games
City guides
E-mail
News, sports, stocks, and weather
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What’s the best Internet
connection?
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75
Conclusion
You should now be able to:
– Describe the characteristics of various networks
– Diagram Shannon’s model of a communications
network
– List types of cables
– List network devices
– Describe the role of communications protocols and list
some protocols associated with the Internet and LANs
– Explain packet switching and circuit switching
– Explain packet switching and circuit switching
– Recount the history of the Internet
Chapter 5: Internet and LAN Technology
76
Conclusion
You should now be able to:
– Draw a conceptual diagram illustrating the Internet
backbone, NAPs, NSPs, routers, and ISPs
– Explain Ping and Traceroute
– Explain the differences between permanent IP
addresses, dynamic IP addresses, private IP
addresses, and domain names
– Describe the advantages and disadvantages of dial-up,
cable modem, DSL, ISDN, T1, T2, and wireless
Internet access
– Explain when and why it is important to implement
security measures such as antivirus software, firewalls,
and Network Address Translation
Chapter 5: Internet and LAN Technology
77