Transcript Chapter 5 Complete

Chapter 5
LANs and WLANs
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
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5
SECTION
A
Network Building Blocks
Network Classifications
LAN Standards
Network Devices
Clients, Servers, and Peers
Physical Topology
Network Links
Communications Protocols
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5 Network Classifications
Personal Area Network (PAN) – interconnection of
personal digital devices
Neighborhood Area Network (NAN) – connectivity
spread over several buildings
Local Area Network (LAN) – usually connects
computers in a single building
Metropolitan Area Network (MAN) – public highspeed network with range of about 50 miles
Wide Area Network (WAN) – consists of several
smaller networks
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5 LAN Standards
LAN technologies are standardized by the
Institute of Electrical and Electronics
Engineers (IEEE) Project 802 – Local
Network Standards
– IEEE 802.3
– Ethernet
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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
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5 Network Devices
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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
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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
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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
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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
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5 Communications Protocols
A packet is a “parcel” of
data that is sent across
a computer network
– Circuit-switching
technology vs. packet
switching technology
• Voice over IP (VoIP)
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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
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5
SECTION
B
Wired Networks
Wired Network Basics
HomePNA and Powerline Networks
Ethernet
Ethernet Equipment
Ethernet Setup
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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
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5 HomePNA and
Powerline Networks
HomePNA networks utilize existing telephone
wiring to connect network devices
– Special NICs and cables are required
Powerline networks transmit data over power
lines as low-frequency radio waves
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5 Ethernet
Simultaneously broadcasts data packets to
all network devices
– IEEE 802.3
– CSMA/CD protocol
Vary in speed from 10Mbps to 10Gbps
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5 Ethernet
On an Ethernet, data
travels on a first come,
first served basis. If two
workstations attempt to
send data at the same
time, a collision occurs.
That data must be
resent.
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5 Ethernet Equipment
Checking a workstation
for an Ethernet port
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5 Ethernet Equipment
Ethernet adapter (designed to support the
Ethernet protocols)
Network hub
Network switch
Network router
RJ45 connector
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5 Ethernet Setup
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5 Ethernet Setup
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5 Ethernet Setup
The Network Connection window helps you
check your connection
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5
SECTION
C
Wireless Networks
Wireless Basics
Bluetooth
Wi-Fi
Wi-Fi Equipment
Wi-Fi Setup
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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
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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
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5 Wi-Fi
Wireless networking technologies that are
compatible with Ethernet
MMO technology uses two or more antennae
to send multiple sets of signals
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5 Wi-Fi Equipment
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5 Wi-Fi Equipment
If your computer is not pre-equipped with
wireless circuitry, you can purchase and
install a Wi-Fi card
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5 Wi-Fi Equipment
Wireless network setups
– Wireless ad-hoc network
– Wireless infrastructure network
• Wireless
access point
• Wireless
router
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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
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5 Wi-Fi Setup
Enter an SSID for the network
Activate WEP, WPA, or WPA2 and create an
encryption key
Set up the wireless workstations
Connect an Internet access device
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5 Wi-Fi Setup
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5
SECTION
D
Using LANs
LAN Advantages and Challenges
Sharing Files
Sharing Printers
LAN Parties
Troubleshooting
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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
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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 a
“snooping” computer
Networked computers are susceptible to an
increasing number of worms, Trojan horses, and
blended threats
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5 Wi-Fi Setup
Change the
default password
for your router
when you install a
wireless network.
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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
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5 Sharing Files
In this drive mapping
example, a server’s drive
C is mapped as drive F
by a workstation. After the
mapping is complete, the
server’s hard disk appears
in the workstation’s
directory as drive F and
can be used just as though
it were a drive connected
directly to the workstation.
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5 Sharing Files
To allow other network
users to access files or
folders on your Windows
computer, you have to
designate them as
shared.
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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
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5 Sharing Printers
In Windows, use the Printers and Faxes
dialog box to allow other users to share the
printer attached to your workstation
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5 LAN Parties
A LAN party is a
gathering of people
who connect their own
computers to a LAN,
usually to play
multiplayer computer
games
– No special hardware
usually is required
– Game must have
multiplayer capability
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5 Troubleshooting
Network problems can stem from a variety of
sources
– Cables
– Signal strength
– Interference
– Network devices
– Security
– Settings
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5
SECTION
E
Security Through Encryption
Wi-Fi Security
Encryption
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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
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5 Wi-Fi Security
An offshoot of war driving is a gambit called
war chalking
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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
Activate encryption by using a wireless
network key
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5 Wi-Fi Security
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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
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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 method
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5 Encryption
Public key encryption (PKE) eliminates keydistribution problem, by using one key to
encrypt a message and another key to
decrypt the message
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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) software
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Chapter 5 Complete
LANs and WLANs