Chapter 5 LANs and WLANs

Chapter Contents Section A: Network Building Blocks Section B: Wired Networks Section C: Wireless Networks Section D: Using LANs Section E: Security Through Encryption Chapter 5: LANs and WLANs

FastPoll True/False Questions Answer 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. Chapter 5: LANs and WLANs

FastPoll True/False Questions Answer A for True and B for False 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. Chapter 5: LANs and WLANs

FastPoll True/False Questions Answer A for True and B for False 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. Chapter 5: LANs and WLANs

Network Building Blocks Network Classifications LAN Standards Network Devices Clients, Servers, and Peers Physical Topology Network Links Communications Protocols Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Network Devices Figure 5-3 Chapter 5: LANs and WLANs

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 Figure 5-4 and 5-5 Chapter 5: LANs and WLANs

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 Figure 5-6 Chapter 5: LANs and WLANs

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 Figure 5-7 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Communications Protocols A packet is a “parcel” of data that is sent across a computer network Circuit-switching technology vs. packet switching technology Figure 5-11 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Wired Networks Wired Network Basics HomePNA and Powerline Networks Ethernet Ethernet Equipment Ethernet Setup Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Figure 5-12 Chapter 5: LANs and WLANs

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 Figures 5-13 and 5-14 Chapter 5: LANs and WLANs

Ethernet Simultaneously broadcasts data packets to all network devices IEEE 802.3 CSMA/CD protocol Vary in speed from 10Mbps to 100Gbps Figure 5-15 Chapter 5: LANs and WLANs

Ethernet 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. Figure 5-16 Chapter 5: LANs and WLANs

Ethernet Equipment Figure 5-18 Chapter 5: LANs and WLANs

Ethernet Equipment Ethernet adapter (designed to support the Ethernet protocols) Network hub Network switch Network router RJ45 connector Figures 5-19 and 5-20 and 5-21 Chapter 5: LANs and WLANs

Ethernet Setup Chapter 5: LANs and WLANs

Ethernet Setup Figure 5-23 Chapter 5: LANs and WLANs

Ethernet Setup Most routers are configured using a browser. You should change the network administrator password, then verify that DHCP is enabled Figure 5-24 Chapter 5: LANs and WLANs

Wireless Networks Wireless Basics Bluetooth Wi-Fi Wi-Fi Equipment Wi-Fi Setup Chapter 5: LANs and WLANs

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 while you set up the network. 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. Chapter 5: LANs and WLANs

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 Figure 5-25 Chapter 5: LANs and WLANs

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 Figures 5-27 and 5-28 Chapter 5: LANs and WLANs

Wi-Fi Wireless networking technologies that are compatible with Ethernet MIMO technology uses two or more antennas to send multiple sets of signals Figure 5-29 Chapter 5: LANs and WLANs

Wi-Fi Equipment Figure 5-31 Chapter 5: LANs and WLANs

Wi-Fi Equipment If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi adapter Figure 5-33 Chapter 5: LANs and WLANs

Wi-Fi Equipment Wireless network setups Wireless ad-hoc network Wireless infrastructure network Wireless access point Wireless router Figure 5-34 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Wi-Fi Setup Figure 5-35 Chapter 5: LANs and WLANs

Using LANs LAN Advantages and Challenges Sharing Files Sharing Printers LAN Parties Troubleshooting Chapter 5: LANs and WLANs

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

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 Chapter 5: LANs and WLANs

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 a “snooping” computer Networked computers are susceptible to an increasing number of worms, Trojan horses, and blended threats Chapter 5: LANs and WLANs

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 Figure 5-41 Chapter 5: LANs and WLANs

Sharing Files Figure 5-42 Chapter 5: LANs and WLANs

Sharing Files Figure 5-43 Chapter 5: LANs and WLANs

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 Figure 5-45 Chapter 5: LANs and WLANs

Sharing Printers You can designate the printer attached to your computer as sharable over the network. Figure 5-46 Chapter 5: LANs and WLANs

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 Figure 5-48 Chapter 5: LANs and WLANs

Troubleshooting Network problems can stem from a variety of sources Cables Signal strength Security Interference Network devices Settings Figure 5-49 Chapter 5: LANs and WLANs

Security Through Encryption Wi-Fi Security Encryption Chapter 5: LANs and WLANs

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. Chapter 5: LANs and WLANs

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 Figure 5-50 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Wi-Fi Security Figure 5-52 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

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 Chapter 5: LANs and WLANs

Encryption Public key encryption (PKE) eliminates key-distribution problem, by using one key to encrypt a message and another key to decrypt the message Figure 5-55 Chapter 5: LANs and WLANs

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 Figure 5-56 Chapter 5: LANs and WLANs

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? 053300 Are broadband providers justified in limiting the terms of their service agreements to “one subscription, one customer”? Chapter 5: LANs and WLANs

Chapter 5 Complete LANs and WLANs