局域网与广域网

1、5Chapter 5: LANs and WLANs2Chapter Contents Section A: Network Building Blocks Section B: Wired Networks Section C: Wireless Networks Section D: Using LANs Section E: Security Through Encryption5FastPoll True/False QuestionsAnswer A for True and B for False 050100 In a network, a server is a compute

2、r 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 compute

3、rs MAC address. 050500 Some network technologies use home telephone or electric cabling for computer networks. Chapter 5: LANs and WLANs35FastPoll True/False QuestionsAnswer A for True and B for False050600 The most popular type of wired network is Ethernet. 050700 Network speeds are measured in meg

4、abytes 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 WLANs45FastPoll True/False QuestionsAnswer A for True and B for False051000 A wireless infrastructure network uses a centralized broadcast

5、ing 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

6、 5: LANs and WLANs55SECTIONAChapter 5: LANs and WLANs6 Network Classifications LAN Standards Network Devices Clients, Servers, and Peers Physical Topology Network Links Communications Protocols5Question052100 Networks come in many sizes and use many different technologies, yet they all need to commu

7、nicate with each other. What is the key to network intercommunication? A. Packet switching B. Network protocols C. Network topology D. Peer-to-peer technologyChapter 5: LANs and WLANs75Chapter 5: LANs and WLANs8Network Classifications Personal Area Network (PAN) interconnection of personal digital d

8、evices 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 networks5Chapter 5: LANs and WLANs9LAN Standards LAN technologies are standardize

9、d by the Institute of Electrical and Electronics Engineers (IEEE) Project 802 Local Network Standards IEEE 802.3 ARCnet Token Ring FDDI Ethernet5Chapter 5: LANs and WLANs10Network Devices Each connection point on a network is referred to as a node To connect to a LAN, a computer requires network cir

10、cuitry, 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

11、signals, or routes data to its destination5Network DevicesChapter 5: LANs and WLANs115Chapter 5: LANs and WLANs12Clients, 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 clie

12、nt/server mode5Chapter 5: LANs and WLANs13Physical 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

13、 two networks5Chapter 5: LANs and WLANs14Network 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 Narrowband5Chapter 5: LANs and WLANs15Communications Protocols Rules for eff

14、iciently 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 data5Chapter 5: LANs and WLANs16Communications Protocols A packet is a “pa

15、rcel” of data that is sent across a computer network Circuit-switching technology vs. packet switching technology5Chapter 5: LANs and WLANs17Communications 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

16、 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 DHCP5SECTIONBChapter 5: LANs and WLANs18 Wired Network Basics HomePNA and Powerline Networks Ethernet Ethernet Equipment Ethernet Setup5Que

17、stion052200 Suppose youre 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 fil

18、e server D. A HomePlug Ethernet portChapter 5: LANs and WLANs195Chapter 5: LANs and WLANs20Wired 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 mobility5Chapter 5: LANs and WLANs21

19、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 LAN5Chapter 5: LANs and WLANs22Ethernet Simultaneou

20、sly broadcasts data packets to all network devices IEEE 802.3 CSMA/CD protocol Vary in speed from 10Mbps to 100Gbps5Chapter 5: LANs and WLANs23EthernetOn 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

21、data must be resent.5Ethernet EquipmentChapter 5: LANs and WLANs245Chapter 5: LANs and WLANs25Ethernet Equipment Ethernet adapter (designed to support the Ethernet protocols) Network hub Network switch Network router RJ45 connector5Chapter 5: LANs and WLANs26Ethernet Setup5Ethernet SetupChapter 5: L

22、ANs and WLANs275Ethernet SetupChapter 5: LANs and WLANs28Most routers are configured using a browser. You shouldchange the network administrator password, then verify that DHCP is enabled5SECTIONCChapter 5: LANs and WLANs29 Wireless Basics Bluetooth Wi-Fi Wi-Fi Equipment Wi-Fi Setup5Question 052300

23、When youre 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 dont know the networks encryption key. C. Make sure SSID i

24、s broadcasting so that your network is protected by strong encryption. D. Activate SSID broadcasting or else the network devices wont be able to send data to the router.Chapter 5: LANs and WLANs305Chapter 5: LANs and WLANs31Wireless Basics A wireless network transports data from one device to anothe

25、r without cables or wires RF signals Transceiver Microwaves Infrared light Slower than wired networks Security concerns5Chapter 5: LANs and WLANs32Bluetooth Bluetooth is a short-range, wireless network technology designed to make its own connections between electronic devices, without wires, cables,

26、 or any direct action from a user5Chapter 5: LANs and WLANs33Wi-Fi Wireless networking technologies that are compatible with Ethernet MIMO technology uses two or more antennas to send multiple sets of signals5Chapter 5: LANs and WLANs34Wi-Fi Equipment5Chapter 5: LANs and WLANs35Wi-Fi Equipment If yo

27、ur computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi adapter5Chapter 5: LANs and WLANs36Wi-Fi Equipment Wireless network setups Wireless ad-hoc network Wireless infrastructure network Wireless access point Wireless router5Chapter 5: LANs and WLANs37Wi-Fi Setu

28、p Set up the router Connect to the router with a computer Configure the router Access the router setup utility Create a new router password5Chapter 5: LANs and WLANs38Wi-Fi Setup Enter an SSID for the network Activate WEP, WPA, or PSK and create an encryption key Set up the wireless workstations Con

29、nect an Internet access device5Wi-Fi SetupChapter 5: LANs and WLANs395SECTIONDChapter 5: LANs and WLANs40 LAN Advantages and Challenges Sharing Files Sharing Printers LAN Parties Troubleshooting5Question052400 There are many ways to share files among the computers on a network. Which one of the foll

30、owing 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 WLANs415Chapter 5

31、: LANs and WLANs42LAN 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 sp

32、ecialized peripheral devices5Chapter 5: LANs and WLANs43LAN 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 Networke

33、d computers are susceptible to an increasing number of worms, Trojan horses, and blended threats5Chapter 5: LANs and WLANs44Sharing 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 a

34、nd password5Sharing FilesChapter 5: LANs and WLANs455Sharing FilesChapter 5: LANs and WLANs465Chapter 5: LANs and WLANs47Sharing 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-

35、in networking5Sharing PrintersChapter 5: LANs and WLANs48You can designate the printer attached to your computer assharable over the network.5Chapter 5: LANs and WLANs49LAN Parties A LAN party is a gathering of people who connect their own computers to a LAN, usually to play multiplayer computer gam

36、es No special hardware usually is required Game must have multiplayer capability5Chapter 5: LANs and WLANs50Troubleshooting Network problems can stem from a variety of sources Cables Signal strength Security Interference Network devices Settings5SECTIONEChapter 5: LANs and WLANs51 Wi-Fi Security Enc

37、ryption5Question052500 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 WLANs525Chapte

38、r 5: LANs and WLANs53Wi-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 area5Chapter 5: LANs and WLANs54Wi-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 key5Wi-Fi Se