LANs and WLANs

Download Report

Transcript LANs and WLANs

Chapter 5
LANs and WLANs
Computer Concepts 2012
5 Chapter Contents
 Section A: Network Building Blocks
 Section B: Wired Networks
 Section C: Wireless Networks
 Section D: Using LANs
 Section E: Security Through Encryption
Chapter 5: LANs and WLANs
2
5 FastPoll True/False Questions
Answer A for True and B for False
 050100 In a network, a server is a computer that provides
services to other computers called peers.
 050200 Star, ring, and mesh are examples of network
topologies.
 050300 When you send an e-mail message over a network,
it is chopped up into packets.
 050400 The IP address assigned to your computer on the
Internet is derived from your computer’s MAC address.
 050500 Some network technologies use home telephone or
electric cabling for computer networks.
Chapter 5: LANs and WLANs
3
5 FastPoll True/False Questions
Answer A for True and B for False
050600 The most popular type of wired network is
Ethernet.
050700 Network speeds are measured in
megabytes and gigabytes.
050800 Many wireless networks use radio waves to
transmit data.
050900 Bluetooth is a wireless technology used for
WANs.
Chapter 5: LANs and WLANs
4
5 FastPoll True/False Questions
Answer A for True and B for False
051000 A wireless infrastructure network uses a
centralized broadcasting device, such as a wireless
access point or router.
051100 Wireless networks are less secure than
wired networks.
051200 WEP, WPA, and PSK are examples of WiFi networks.
051300 Public key encryption uses a public key to
encrypt messages, but a private key is required to
decrypt messages.
Chapter 5: LANs and WLANs
5
5
SECTION
A
Network Building Blocks
 Network Classifications
 LAN Standards
 Network Devices
 Clients, Servers, and Peers
 Physical Topology
 Network Links
 Communications Protocols
Chapter 5: LANs and WLANs
6
5 Question
052100 Networks come in many sizes and use
many different technologies, yet they all need to
communicate with each other. What is the key to
network intercommunication?
– A. Packet switching
– B. Network protocols
– C. Network topology
– D. Peer-to-peer technology
Chapter 5: LANs and WLANs
7
5 Network Classifications
 Personal Area Network (PAN) – interconnection of personal
digital devices or consumer electronics
 Local Area Network (LAN) – usually connects computers in a
single building
 Metropolitan Area Network (MAN) – public high-speed
network with range of about 50 miles
 Wide Area Network (WAN) – covers a large geographical
area and typically consists of several smaller networks
Chapter 5: LANs and WLANs
8
5 LAN Standards
 LAN technologies are standardized by the Institute of
Electrical and Electronics Engineers (IEEE) Project 802 –
Local Network Standards
– IEEE 802.3
– ARCnet
– Token Ring
– FDDI
– Ethernet
Chapter 5: LANs and WLANs
9
5 Network Devices
 Each connection point on a network is referred to as a node
 To connect to a LAN, a computer requires network circuitry,
sometimes referred to as a network interface card (NIC)
 A networked peripheral, or network-enabled peripheral, is
any device that contains network circuitry to directly connect
to a network
 A network device, or network appliance, is any electronic
device that broadcasts network data, boosts signals, or
routes data to its destination
Chapter 5: LANs and WLANs
10
5 Network Devices
Chapter 5: LANs and WLANs
11
5 Clients, Servers, and Peers
 Network devices can function as clients or as servers
– Application server
– File server
– Print server
 Networks that include one or more servers can operate in
client/server mode
Chapter 5: LANs and WLANs
12
5 Physical Topology
 The arrangement of devices in a network is referred to as its
physical topology
– Star
– Ring
– Bus
– Mesh
– Tree
 Two similar networks can
be connected by a device
called a bridge
 Gateway is a generic term
for any device or software
code used to join two networks
Chapter 5: LANs and WLANs
13
5 Network Links
 A communications channel, or link, is a physical path or
frequency for signal transmissions
 Bandwidth is the transmission capacity of a communications
channel
– Broadband
– Narrowband
Chapter 5: LANs and WLANs
14
5 Communications Protocols
 Rules for efficiently transmitting data from one network node
to another:
– Divide messages into packets
– Affix addresses to packets
– Initiate transmission
– Regulate flow of data
– Check for transmission errors
– Acknowledge receipt of transmitted data
Chapter 5: LANs and WLANs
15
5 Communications Protocols
 A packet is a “parcel” of
data that is sent across a
computer network
– Circuit-switching
technology vs. packet
switching technology
Chapter 5: LANs and WLANs
16
5 Communications Protocols
 Every packet that travels over a network includes the
address of its destination device
 A MAC address is a unique number assigned to a network
interface card when it is manufactured
 An IP address is a series of numbers used to identify a
network device
 IP addresses can also be obtained through DHCP
Chapter 5: LANs and WLANs
17
5
SECTION
B
Wired Networks
 Wired Network Basics
 Ethernet
 Ethernet Equipment
 Ethernet Setup
Chapter 5: LANs and WLANs
18
5 Question
052200 Suppose you’re setting up a network in your
home or apartment. You want all of the computers
to access the cable modem that provides Internet
access. What is the one additional component that
you should purchase to tie the network together?
– A. A router
– B. A network interface card
– C. A file server
– D. A HomePlug Ethernet port
Chapter 5: LANs and WLANs
19
5 Wired Network Basics
 A wired network uses cables to connect network devices
 Wired networks are fast, secure, and simple to configure
 Devices tethered to cables
have limited mobility
Chapter 5: LANs and WLANs
20
5 Ethernet
 Simultaneously broadcasts data packets to all network
devices
– IEEE 802.3
– CSMA/CD protocol
 Vary in speed from 10Mbps to 100Gbps
Chapter 5: LANs and WLANs
21
5 Ethernet
Chapter 5: LANs and WLANs
22
5 Ethernet Equipment
Chapter 5: LANs and WLANs
23
5 Ethernet Equipment
 Ethernet adapter (designed to support the Ethernet
protocols)
 Network hub
 Network switch
 Network router
 RJ45 connector
Chapter 5: LANs and WLANs
24
5 Ethernet Setup
Chapter 5: LANs and WLANs
25
5 Ethernet Setup
Chapter 5: LANs and WLANs
26
5 Ethernet Setup
Chapter 5: LANs and WLANs
27
5
SECTION
C
Wireless Networks
 Wireless Basics
 Bluetooth
 Wi-Fi
 Wi-Fi Equipment
 Wi-Fi Setup
Chapter 5: LANs and WLANs
28
5 Question
 052300 When you’re setting up a wireless network, you see
an option asking if you want to broadcast the network SSID.
You should:
– A. Change the default SSID and broadcast it.
– B. Turn SSID broadcasting off so that hackers don’t
know the network’s encryption key.
– C. Make sure SSID is broadcasting so that your network
is protected by strong encryption.
– D. Activate SSID broadcasting or else the network
devices won’t be able to send data to the router.
Chapter 5: LANs and WLANs
29
5 Wireless Basics
 A wireless network transports data from one device to
another without cables or wires
– RF signals
• Transceiver
– Microwaves
– Infrared light
 Slower than wired networks
 Security concerns
Chapter 5: LANs and WLANs
30
5 Bluetooth
 Bluetooth is a short-range, wireless network technology
designed to make its own connections between electronic
devices, without wires, cables, or any direct action from a
user
Chapter 5: LANs and WLANs
31
5 Wi-Fi
 Wireless networking technologies that are compatible with
Ethernet
 MIMO technology uses two or more antennas to send
multiple sets of signals between network devices
Chapter 5: LANs and WLANs
32
5 Wi-Fi Equipment
Chapter 5: LANs and WLANs
33
5 Wi-Fi Equipment
 If your computer is not pre-equipped with wireless circuitry,
you can purchase and install a Wi-Fi adapter
Chapter 5: LANs and WLANs
34
5 Wi-Fi Equipment
 Wireless network setups
– Wireless ad-hoc network
– Wireless infrastructure network
• Wireless
access point
• Wireless
router
– MiFi
Chapter 5: LANs and WLANs
35
5 Wi-Fi Setup
 Set up the router
 Connect to the router with a computer
 Configure the router
 Access the router setup utility
 Create a new router password
Chapter 5: LANs and WLANs
36
5 Wi-Fi Setup
 Enter an SSID for the network
 Activate WEP, WPA, or PSK and create an encryption key
 Set up the wireless workstations
 Connect an Internet access device
Chapter 5: LANs and WLANs
37
5 Wi-Fi Setup
Chapter 5: LANs and WLANs
38
5
SECTION
D
Using LANs
 LAN Advantages and Challenges
 Sharing Files
 Sharing Printers
 Network Troubleshooting
Chapter 5: LANs and WLANs
39
5 Question
052400 There are many ways to share files among
the computers on a network. Which one of the
following is the LEAST secure way to share files?
– A. Use a file server.
– B. Activate file sharing for the root directory of all
the computers in the network.
– C. Designate specific folders on your computer
as shared.
– D. Put files you want to share in the Public
folder.
Chapter 5: LANs and WLANs
40
5 LAN Advantages
and Challenges
 LANs enable people to work together
 Sharing networked software can reduce costs
 Sharing data on a LAN can increase productivity
 Sharing networked hardware can reduce costs
 Sharing networked hardware can provide access to a wide
range of services and specialized peripheral devices
Chapter 5: LANs and WLANs
41
5 LAN Advantages
and Challenges
 Resources become unavailable when network malfunctions
 Networks may be vulnerable to unauthorized access
– More vulnerable than standalone computers
 Wireless networks can be tapped from any computers within
range of the wireless signal
 Networked computers are susceptible to an increasing
number of worms, Trojan horses, and blended threats
Chapter 5: LANs and WLANs
42
5 Sharing Files
 If you use Windows, it
automatically detects
available LANs any time
you turn on a workstation
 To connect to a shared
resource, you might be
asked for a user ID and
password
Chapter 5: LANs and WLANs
43
5 Sharing Files
Chapter 5: LANs and WLANs
44
5 Sharing Files
Chapter 5: LANs and WLANs
45
5 Sharing Files
 A homegroup is a collection of trusted networked computers
that automatically share files and folders
Chapter 5: LANs and WLANs
46
5 Sharing Printers
 Three setups allow for printer sharing:
– Set up printer sharing using a workstation printer
– Set up printer sharing using a print server
– Install printer with built-in networking
Chapter 5: LANs and WLANs
47
5 Sharing Printers
Chapter 5: LANs and WLANs
48
5 Troubleshooting
 Network problems can stem from a variety of sources
– Cables
– Signal strength
– Security
– Interference
– Network devices
– Settings
– Switches
Chapter 5: LANs and WLANs
49
5
SECTION
E
Security Through Encryption
 Wi-Fi Security
 Encryption
Chapter 5: LANs and WLANs
50
5 Question
052500 As part of the process of setting up a wired
network, what should you remember to do?
– A. Assign an IP address to each network device.
– B. Remove the Ethernet card from any computer
that has one.
– C. Enable wireless security.
– D. Disable the SSID.
Chapter 5: LANs and WLANs
51
5 Wi-Fi Security
 Wireless networks are much more susceptible to
unauthorized access and use than wired networks
 LAN jacking, or war driving, is the practice of intercepting
wireless signals by cruising through an area
Chapter 5: LANs and WLANs
52
5 Wi-Fi Security
 Wireless encryption scrambles data transmitted between
wireless devices and then unscrambles the data only on
devices that have a valid encryption key
– WEP (Wired Equivalent Privacy)
– WPA (Wi-Fi Protected Access)
– WPA2
– PSK
 Activate encryption by using a wireless network key
Chapter 5: LANs and WLANs
53
5 Wi-Fi Security
Chapter 5: LANs and WLANs
54
5 Encryption
 Encryption transforms a message so that its contents are
hidden from unauthorized readers
– Plaintext has not yet been encrypted
– An encrypted message is referred to as ciphertext
 Decryption is the opposite of encryption
– Cryptographic algorithm
– Cryptographic key
Chapter 5: LANs and WLANs
55
5 Encryption
 Weak vs. strong encryption
 AES (Advanced Encryption Standard)
 Encryption methods can be broken by the use of expensive,
specialized, code-breaking computers
– Brute force attack
Chapter 5: LANs and WLANs
56
5 Encryption
 Public key encryption (PKE) eliminates key-distribution
problem, by using one key to encrypt a message and
another key to decrypt the message
Chapter 5: LANs and WLANs
57
5 Encryption
 When personal computer users want to encrypt e-mail or
other documents, they turn to public key encryption software
called PGP (Pretty Good Privacy)
Chapter 5: LANs and WLANs
58
5 What Do You Think?
 053100 Have you ever accessed a free WLAN?
– A. Yes
B. No
C. Not sure
 053200 Do you believe that rogue WLANs can survive
alongside for-profit broadband ISPs?
– A. Yes
B. No
C. Not sure
 053300 Are broadband providers justified in limiting the
terms of their service agreements to “one subscription, one
customer”?
– A. Yes
B. No
C. Not sure
Chapter 5: LANs and WLANs
59
Chapter 5 Complete
Computer Concepts 2012