chapter 5
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Chapter 5. LANs and WANs. Network Classifications LAN Standards Network Devices Clients, Servers, and Peers Physical Topology Network Links Communications Protocols. Network Building Blocks. Network Classifications. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 5LANs and WANs
Network Building Blocks
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Network Classifications
LAN Standards
Network Devices
Clients, Servers, and Peers
Physical Topology
Network Links
Communications Protocols
Network Classifications
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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
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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
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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
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Clients, Servers, and Peers
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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
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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
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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
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Communications Protocols
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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
Communications Protocols
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A packet is a “parcel” of data that is sent across a computer network Circuit-switching technology vs.
packet switching technology
Communications Protocols
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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
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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
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Wired Network Basics
HomePNA and Powerline Networks
Ethernet
Ethernet Equipment
Ethernet Setup
Wired Network Basics
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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
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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
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Simultaneously broadcasts data packets to all network devices IEEE 802.3 CSMA/CD protocol
Vary in speed from 10Mbps to 100Gbps
Ethernet
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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
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Ethernet Equipment
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Ethernet adapter (designed to support the Ethernet protocols)
Network hub
Network switch
Network router
RJ45 connector
Ethernet Setup
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Ethernet Setup
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Ethernet Setup
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Most routers are configured using a browser. You shouldchange the network administrator password, then verify that DHCP is enabled
Question
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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
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Wireless Basics
Bluetooth
Wi-Fi
Wi-Fi Equipment
Wi-Fi Setup
Wireless Basics
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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
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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
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Wireless networking technologies that are compatible with Ethernet
MIMO technology uses two or more antennas to send multiple sets of signals
Wi-Fi Equipment
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Wi-Fi Equipment
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If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi adapter
Wi-Fi Equipment
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Wireless network setups Wireless ad-hoc network Wireless infrastructure network
Wireless access point
Wireless router
Wi-Fi Setup
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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
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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
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Using LANs
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LAN Advantages and Challenges
Sharing Files
Sharing Printers
LAN Parties
Troubleshooting
LAN Advantages and ChallengesPros:
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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:
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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
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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
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Sharing Files
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Sharing Printers
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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
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You can designate the printer attached to your computer assharable over the network.
LAN Parties
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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
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Network problems can stem from a variety of sources Cables Signal strength Security Interference Network devices Settings
Question
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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
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Wi-Fi Security
Encryption
Wi-Fi Security
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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
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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
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Encryption
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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
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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
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Public key encryption (PKE) eliminates key-distribution problem, by using one key to encrypt a message and another key to decrypt the message
Encryption
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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
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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
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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.
FastPoll True/False QuestionsAnswer A for True and B for False
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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.
FastPoll True/False QuestionsAnswer A for True and B for False
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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.