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Chapter 5
LANs and WANs
2
Network Building Blocks

Network Classifications

LAN Standards

Network Devices

Clients, Servers, and Peers

Physical Topology

Network Links

Communications Protocols
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Network Classifications

Personal Area Network (PAN) – interconnection of personal digital
devices

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) – consists of several smaller networks
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LAN Standards

LAN technologies are standardized by the Institute of Electrical and
Electronics Engineers (IEEE) Project 802 – Local Network Standards

IEEE 802.3 – current standard




ARCnet
Token Ring
FDDI
Ethernet – most common today thru Wi-Fi
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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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Network Devices
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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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Physical Topology

The arrangement of devices in a network is referred to as its physical topology

Two similar networks can
be connected by a device
called a bridge (hardware)

Gateway is a generic term
for any device or software
code used to join two networks
(software)
 Star
 Ring
 Bus
 Mesh
 Tree
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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 (cable)
Narrowband (dsl)
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Broadband - Structure
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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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Communications Protocols

A packet is a “parcel” of data that is
sent across a computer network

Circuit-switching technology vs.
packet switching technology
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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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Question
 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
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Wired Networks
 Wired Network Basics
 HomePNA and Powerline Networks
 Ethernet
 Ethernet Equipment
 Ethernet Setup
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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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HomePNA and Powerline Networks

HomePNA networks utilize existing telephone wiring or coaxial cables to
connect network devices


Special NICs and cables are required
A powerline network uses premises electrical wiring to form the infrastructure
for a LAN
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Ethernet

Simultaneously broadcasts data packets to all network devices



IEEE 802.3
CSMA/CD protocol
Vary in speed from 10Mbps to 100Gbps
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Ethernet
On an Ethernet,
data travels on a
first-come, firstserved basis. If two
workstations
attempt to send
data at the same
time, a collision
occurs.
That data must be
resent.
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Ethernet Equipment
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Ethernet Equipment

Ethernet adapter (designed to support the
Ethernet protocols)

Network hub

Network switch

Network router

RJ45 connector
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Ethernet Setup
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Ethernet Setup
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Ethernet Setup
Most routers are
configured using a
browser. You should
change the network
administrator
password, then
verify that DHCP is
enabled
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Question
 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
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Wireless Networks
 Wireless Basics
 Bluetooth
 Wi-Fi
 Wi-Fi Equipment
 Wi-Fi Setup
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Wireless Basics

A wireless network transports data from one
device to another without cables or wires

RF signals(radio frequencies)



Transceiver
Microwaves
Infrared light

Slower than wired networks

Security concerns
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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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Wi-Fi

Wireless networking technologies that are compatible with Ethernet

MIMO technology uses two or more antennas to send multiple sets of
signals
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Wi-Fi Equipment
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Wi-Fi Equipment

If your computer is not pre-equipped with wireless circuitry, you can
purchase and install a Wi-Fi adapter
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Wi-Fi Equipment

Wireless network setups


Wireless ad-hoc network
Wireless infrastructure network

Wireless
access point

Wireless
router
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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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Wi-Fi Setup

Enter an SSID (service set ID) for the network

Activate WEP (Wired Equivalent Privacy) , WPA (Wi-Fi Protected
Access), or PSK (pre-shared Key) and create an encryption key

Set up the wireless workstations

Connect an Internet access device
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Wi-Fi Setup
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Using LANs
 LAN Advantages and Challenges
 Sharing Files
 Sharing Printers
 LAN Parties
 Troubleshooting
Chapter 5: LANs and WLANs
LAN Advantages and Challenges
Pros:

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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LAN Advantages and Challenges
Cons:

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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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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Sharing Files
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Sharing Files
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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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Sharing Printers
You can designate
the printer attached
to your computer as
sharable over the
network.
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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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Troubleshooting

Network problems can stem from a variety of
sources






Cables
Signal strength
Security
Interference
Network devices
Settings
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Question
 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.
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Security Through Encryption
 Wi-Fi Security
 Encryption
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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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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 (Pre-shared Key)
Activate encryption by using a wireless network key
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Wi-Fi Security
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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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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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Encryption

Public key encryption (PKE) eliminates key-distribution problem, by
using one key to encrypt a message and another key to decrypt the
message
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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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Question
 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.
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FastPoll True/False Questions
Answer A for True and B for False

In a network, a server is a computer that provides services to other
computers called peers.

Star, ring, and mesh are examples of network topologies.

When you send an e-mail message over a network, it is chopped up
into packets.

The IP address assigned to your computer on the Internet is derived
from your computer’s MAC address.

Some network technologies use home telephone or electric cabling for
computer networks.
Chapter 5: LANs and WLANs
FastPoll True/False Questions
Answer A for True and B for False
 The most popular type of wired network is
Ethernet.
 Network speeds are measured in
megabytes and gigabytes.
 Many wireless networks use radio waves to
transmit data.
 Bluetooth is a wireless technology used for
WANs.
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59
FastPoll True/False Questions
Answer A for True and B for False
 A wireless infrastructure network uses a
centralized broadcasting device, such as a
wireless access point or router.
 Wireless networks are less secure than wired
networks.
 WEP, WPA, and PSK are examples of Wi-Fi
networks.
 Public key encryption uses a public key to
encrypt messages, but a private key is required
to decrypt messages.
Chapter 5: LANs and WLANs