Computer Concepts 8

1
1
1
1
Chapter 4 File Management, Virus Protection, and
Backup
1
Chapter 1 Computer, Internet, Web, and E-Mail
Basics
2
Chapter 5 Preview

• After this chapter, you should be able to
• Describe the characteristics of various networks
• Diagram Shannons 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

3
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

4
Chapter 5 Outline

• Section A
• Network Building Blocks
• Section B
• Local Area Networks
• Section C
• Internet Technology
• Section D
• Internet Access

5
Chapter 5Internet and LAN Technology

• Section A Network Building Blocks

Computer Concepts 8th EditionParsons/Oja
6
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

Page 226
7
Do networks have disadvantages?

• Primary disadvantage is their vulnerability to
  unauthorized access
• More vulnerable than standalone computers to
  malicious code

Page 226
8
How are networks classified?

• Geographical scope
• Organizational structure
• Physical topology
• Network links
• Bandwidth
• Communications protocols

Page 226
9
Why is geographic scope important?

• Wide Area Network
• Metropolitan Area Network
• Local Area Network
• Neighborhood Area Network
• Personal Area Network

Page 228
10
What is the difference between a client/server
network and a peer-to-peer network?

• Client/server contains servers and clients
• Peer-to-peer (P2P) every computer is considered
  an equal

Page 229
11
How are devices on a network physically arranged?
Star Topology
Tree Topology
Ring Topology
Bus Topology
Mesh Topology
Page 230
12
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

Page 231
13
What are popular network cabling options?

• Todays networks use twisted-pair cables
• UTP (unshielded twisted pair)
• STP (shielded twisted pair)
• Looks similar to telephone cable
• Has square plastic RJ-45 connector

Page 232
14
What are popular network cabling options?

• Another option is coaxial cable
• Resembles cable-TV cable
• Round, silver BNC or F-type connector

Page 232
15
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

Page 232
16
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

Page 233
17
Whats 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

Page 233
18
Whats 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

Page 234
19
How does data travel over a network?

• In 1948, Claude Shannon published an article that
  described a communication model

Page 234
20
How does data travel over a network?
Page 234
21
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

Page 235
22
Whats 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

Page 235
23
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

Page 236
24
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

Page 237
25
Chapter 5Internet and LAN Technology

• Section B Local Area Networks

Computer Concepts 8th EditionParsons/Oja
26
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

Page 238
27
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

Page 238
28
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

Page 238
29
What is the FDDI standard?

• Offers 100 Mbps speeds over fiber-optic cables
• Popular campus network technology

Page 239
30
How does Ethernet work?
Page 239
31
How does Ethernet work?
Page 240
32
How fast is an Ethernet network?
Page 240
33
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

Page 240
34
What equipment is required for Ethernet
installations?
Page 240
35
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

Page 241
36
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

Page 243
37
HomePNA and HomePNC Networks
Page 243
38
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

Page 244
39
How do I set up a simple LAN?
Page 244
40
How do I access network resources?
Page 245
41
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
  thats located on a different workstation

Page 245
42
Chapter 5Internet and LAN Technology

• Section C Internet Technology

Computer Concepts 8th EditionParsons/Oja
43
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 Unions launch of
  Sputnik in 1957, the first artificial satellite
• The ARPANET, created in 1969, connected computers
  at four universities

Page 246
44
How is the Internet structured?
Page 247
45
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

Page 248
46
Is it possible to track data as it travels over
the Internet?
Page 248
47
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

Page 248
48
What kinds of network devices are part of an ISP?
Page 249
49
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

Page 249
50
Is TCP/IP the only Internet Protocol?
Page 249
51
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 sections number cannot exceed 255
• Each address requires 32 bits (8 bits per section)

Page 250
52
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

Page 250
53
Domain Names Whats 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

Page 251
54
Domain Names Whats a domain name?

• Top-level Domains
• biz
• com
• edu
• gov
• info
• int
• mil
• net
• org

Page 251
55
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

Page 252
56
How do I get a domain name?
Page 253
57
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

Page 253
58
Chapter 5Internet and LAN Technology

• Section D Internet Access

Computer Concepts 8th EditionParsons/Oja
59
How does a dial-up connection work?

• While connected to your ISP, your call is routed
  through the telephone companys local switch to
  the ISP

Local Switch
Page 255
60
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)

Page 256
61
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

Page 257
62
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

Page 258
63
How can the cable TV system provide Internet
access?
Page 258
64
Are television and data signals carried over the
same cable?

• Lowest-capacity coaxial cable has far greater
  capacity than POTS lines
• Cables bandwidth is divided among 3 activities

Page 258
65
How do I set up a cable modem connection?
Page 259
66
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

Page 259
67
Whats the significance of becoming part of a
neighborhood network?
Page 260
68
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

Page 260
69
What is DSL?

• DSL (Digital Subscriber Line) is a high-speed,
  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

Page 260
70
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

Page 262
71
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

Page 262
72
How does satellite access work?
Page 262
73
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

Page 264
74
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

Page 265
75
Whats the best Internet connection?
Page 267
76
Conclusion

• You should now be able to
• Describe the characteristics of various networks
• Diagram Shannons 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

77
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