Chapter 5 LANs and WLANs

Computer Concepts 2012

Chapter 5LANs and WLANs

5

Chapter 5: LANs and WLANs 2

Chapter Contents Section A: Network Building Blocks Section B: Wired Networks Section C: Wireless Networks Section D: Using LANs Section E: Security Through Encryption

5 FastPoll True/False QuestionsAnswer 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.



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.



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 Wi-Fi networks.

051300 Public key encryption uses a public key to encrypt messages, but a private key is required to decrypt messages.


5 SECTION A


Network Building Blocks Network Classifications LAN Standards Network Devices Clients, Servers, and Peers Physical Topology Network Links Communications Protocols

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


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

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

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

5 Network Devices


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

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

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

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

5


Communications Protocols A packet is a “parcel” of

data that is sent across a computer network– Circuit-switching

technology vs. packet switching technology

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

5 SECTION B


Wired Networks Wired Network Basics Ethernet Ethernet Equipment Ethernet Setup

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


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

5


Ethernet Simultaneously broadcasts data packets to all network

devices– IEEE 802.3– CSMA/CD protocol

Vary in speed from 10Mbps to 100Gbps

5


Ethernet

5 Ethernet Equipment


5


Ethernet Equipment Ethernet adapter (designed to support the Ethernet

protocols) Network hub Network switch Network router RJ45 connector

5


Ethernet Setup

5 Ethernet Setup


5 SECTION C


Wireless Networks Wireless Basics Bluetooth Wi-Fi Wi-Fi Equipment Wi-Fi Setup

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.


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

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

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

5


Wi-Fi Equipment

5


Wi-Fi Equipment If your computer is not pre-equipped with wireless circuitry,

you can purchase and install a Wi-Fi adapter

5


Wi-Fi Equipment Wireless network setups

– Wireless ad-hoc network– Wireless infrastructure network

• Wireless access point

• Wireless router

– MiFi

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

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

5 Wi-Fi Setup


5 SECTION D


Using LANs LAN Advantages and Challenges Sharing Files Sharing Printers Network Troubleshooting

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

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

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

5 Sharing Files


5 Sharing Files A homegroup is a collection of trusted networked computers

that automatically share files and folders


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

5


Sharing Printers

5


Troubleshooting Network problems can stem from a variety of sources

– Cables– Signal strength– Security– Interference– Network devices– Settings– Switches

5 SECTION E


Security Through Encryption Wi-Fi Security Encryption

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.


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

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

5 Wi-Fi Security


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

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

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

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)

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


Computer Concepts 2012

Chapter 5 Complete

Chapter 5 LANs and WLANs

Documents

Transcript of Chapter 5 LANs and WLANs