LANs and WLANs

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Network Building Blocks Wired Networks Wireless Networks Using LANs Security Through Encryption

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

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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 high-speed network with range of about 50 miles

Wide Area Network (WAN) – consists of several smaller networks

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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 Ethernet

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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

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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

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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

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

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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 Narrowband

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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

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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 Voice over IP (VoIP)

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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

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Wired Network Basics HomePNA and Powerline Networks Ethernet Ethernet Equipment Ethernet Setup

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 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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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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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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Checking a workstation for an Ethernet port

Ethernet adapter (designed to support the Ethernet protocols)

Network hub Network switch Network router RJ45 connector

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The Network Connection window helps you check your connection

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

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

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Wireless network setups Wireless ad-hoc network Wireless infrastructure network

Wireless access point

Wireless router

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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

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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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LAN Advantages and Challenges Sharing Files Sharing Printers LAN Parties Troubleshooting

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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

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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

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Change the default password for your router when you install a wireless network.

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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In this drive mappingexample, a server’s driveC is mapped as drive Fby 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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To allow other network users to access files or folders on your Windows computer, you have to designate them as shared.

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

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Wi-Fi Security Encryption

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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

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An offshoot of war driving is a gambit called war chalking

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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

Activate encryption by using a wireless network key

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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

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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

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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

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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

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