Chapter 5

Chapter 5LANs and WANs

Network Building Blocks

Chapter 5: LANs and WLANs

2

Network Classifications

LAN Standards

Network Devices

Clients, Servers, and Peers

Physical Topology

Network Links

Communications Protocols

Network Classifications


3

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

LAN Standards


4

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

Network Devices


5

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

Network Devices


6

Clients, Servers, and Peers


7

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

Physical Topology


8

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 (hardware)

Gateway is a generic term for any device or software code used to join two networks

(software)

Network Links


9

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)

Broadband - Structure


10



11

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



12

A packet is a “parcel” of data that is sent across a computer network Circuit-switching technology vs.

packet switching technology



13

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

Question


14

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 switchingB. Network protocolsC. Network topologyD. Peer-to-peer technology

Wired Networks


15

Wired Network Basics

HomePNA and Powerline Networks

Ethernet

Ethernet Equipment

Ethernet Setup

Wired Network Basics


16

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

HomePNA and Powerline Networks


17

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

Ethernet


18

Simultaneously broadcasts data packets to all network devices IEEE 802.3 CSMA/CD protocol

Vary in speed from 10Mbps to 100Gbps

Ethernet


19

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.

Ethernet Equipment


20

Ethernet Equipment


21

Ethernet adapter (designed to support the Ethernet protocols)

Network hub

Network switch

Network router

RJ45 connector

Ethernet Setup


22

Ethernet Setup


23

Ethernet Setup


24

Most routers are configured using a browser. You shouldchange the network administrator password, then verify that DHCP is enabled

Question


25

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 routerB. A network interface cardC. A file serverD. A HomePlug Ethernet port

Wireless Networks


26

Wireless Basics

Bluetooth

Wi-Fi

Wi-Fi Equipment

Wi-Fi Setup

Wireless Basics


27

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

Bluetooth


28

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


29

Wi-Fi


30

Wireless networking technologies that are compatible with Ethernet

MIMO technology uses two or more antennas to send multiple sets of signals

Wi-Fi Equipment


31

Wi-Fi Equipment


32

If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi adapter

Wi-Fi Equipment


33

Wireless network setups Wireless ad-hoc network Wireless infrastructure network

Wireless access point

Wireless router

Wi-Fi Setup


34

Set up the router

Connect to the router with a computer

Configure the router

Access the router setup utility

Create a new router password

Wi-Fi Setup


35

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

Wi-Fi Setup


36

Using LANs


37

LAN Advantages and Challenges

Sharing Files

Sharing Printers

LAN Parties

Troubleshooting

LAN Advantages and ChallengesPros:


38

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

LAN Advantages and ChallengesCons:


39

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

Sharing Files


40

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

Sharing Files


41

Sharing Files


42

Sharing Printers


43

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

Sharing Printers


44

You can designate the printer attached to your computer assharable over the network.

LAN Parties


45

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

Troubleshooting


46

Network problems can stem from a variety of sources Cables Signal strength Security Interference Network devices Settings

Question


47

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.

Security Through Encryption


48

Wi-Fi Security

Encryption

Wi-Fi Security


49

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

Wi-Fi Security


50

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

Wi-Fi Security


51

Encryption


52

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

Encryption


53

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

Encryption


54

Public key encryption (PKE) eliminates key-distribution problem, by using one key to encrypt a message and another key to decrypt the message

Encryption


55

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

Question


56

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.

FastPoll True/False QuestionsAnswer A for True and B for False


57

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.



58

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.



59

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

Documents

Transcript of Chapter 5