1. LANs and WLANs Chapter 5

2. 5 Chapter 5: LANs and WLANs2 Chapter Contents  Section A: Network Building Blocks  Section B: Wired Networks  Section C: Wireless Networks  Section D: Using LANs  Section E: Security Through Encryption

3. 5 SECTION A Chapter 5: LANs and WLANs3 Network Building Blocks  Network Classifications  LAN Standards  Network Devices  Clients, Servers, and Peers  Physical Topology  Network Links  Communications Protocols

4. 5 Chapter 5: LANs and WLANs4 Network Classifications  Personal Area Network (PAN) – interconnection of personal digital devices  Neighborhood Area Network (NAN) – connectivity spread over several buildings  Local Area Network (LAN)  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)  Wide Area Network (WAN) – consists of several smaller networks

5. 5 Chapter 5: LANs and WLANs5 LAN Standards  LAN technologies are standardized by the Institute of Electrical and Electronics Engineers (IEEE) Project 802 – Local Network Standards –IEEE 802.3Ethernet –IEEE 802.3 specifies the standards for Ethernet wired local area networks How devices physically signal each other, how devices “share the wire in the wall”, etc. de facto standard –Ethernet is the de facto standard for wired LAN in use today

6. 5 Chapter 5: LANs and WLANs6 Ethernet Frame Structure IEEE 802.3 Ethernet frame  Preamble:  Preamble: 8 bytes  7 bytes with pattern 10101010, followed by one byte with pattern 10101011 (frame delimiter)  used to synchronize receiver, sender clock rates  Addresses:  Addresses: 6 bytes, frame is received by all adapters on a LAN and dropped if address does not match  Type (Length):  Type (Length): 2 bytes, length of data segment (min. 46 bytes)  CRC (Cyclic Redundancy Check):  CRC (Cyclic Redundancy Check): 4 bytes, created by sender, checked by receiver, if error detected, the frame is simply dropped Type 64 – 1518 bytes in length

7. 5 Chapter 5: LANs and WLANs7 Network Devices node  Each connection point on a network is referred to as a node network interface card (NIC)  To connect to a LAN, a computer requires network circuitry, sometimes referred to as a network interface card (NIC) networked peripheral  A networked peripheral, or network-enabled peripheral, is any device that contains network circuitry to directly connect to a network network device  A network device, or network appliance, is any electronic device that broadcasts/re-broadcasts network data, boosts signals, or routes data to its destination

8. 5 Chapter 5: LANs and WLANs8 Network Devices

9. 5 Chapter 5: LANs and WLANs9 Clients, Servers, and Peers clients or as servers  Network devices can function as clients or as servers –Application server –File server –Print server client/server mode  Networks that include one or more servers can operate in client/server mode

10. 5 Chapter 5: LANs and WLANs10 Physical Topology arrangement of devices  The arrangement of devices in a network is referred to as its physical topology –Star: central connection point –Ring: attached to 2 neighbors –Bus: common, shared backbone –Mesh: multiple interconnections –Tree: stars on a bus bridgeswitch  Two similar networks can be connected by a device called a bridge (or switch)  Gateway  Gateway is a generic term for any device or software code used to join two networks

11. 5 Chapter 5: LANs and WLANs11 Network Links communications channelor link  A communications channel, or link, is a physical path or frequency for signal transmissions  Bandwidth  Bandwidth is the transmission capacity of a communications channel (usually expressed in bits/sec, bps) –Broadband –Narrowband

12. 5 Chapter 5: LANs and WLANs12 Communications Protocols transmitting data  Rules (Standards) for efficiently and effectively transmitting data from one network node to another. They define how to: packets –Divide messages into packets addresses –Affix addresses (of the nodes) to packets transmission –Initiate transmission (arbitrate access) –Regulate –Regulate flow of data errors –Check for transmission errors –Acknowledge –Acknowledge receipt of transmitted data (in some protocols)

13. 5 Chapter 5: LANs and WLANs13 Communications Protocols packet  A packet is a “parcel” of data that is sent across a computer network –Circuit-switching –Circuit-switching technology vs. –Packet switching –Packet switching technology The Internet Voice over IP (VoIP) –Advantages of one vs. the other?

14. 5 Chapter 5: LANs and WLANs14 Communications Protocols  Every packet  Every packet that travels over a packet-switched network includes the address of its destination device  Most physical devices have more than one address MAC address  A MAC address is a unique number assigned to a network interface card when it is manufactured IP address  An IP address is a series of numbers used to identify a network device in an internet DHCP  IP addresses can be assigned by registration, or obtained dynamically through DHCP

15. 5 SECTION B Chapter 5: LANs and WLANs15 Wired Networks  Wired Network Basics  HomePNA and Powerline Networks  Ethernet  Ethernet Equipment  Ethernet Setup

16. 5 Chapter 5: LANs and WLANs16 Wired Network Basics cables  A wired network uses cables to connect network devices fastsecuresimple  Wired networks are fast, secure, and simple to configure and well-proven limited mobility  Devices tethered to cables have limited mobility

17. 5 Chapter 5: LANs and WLANs17 HomePNA and Powerline Networks  HomePNA (HPNA)  HomePNA (HPNA) networks utilize existing telephone wiring to connect network devices –Special NICs and cables are required  Powerline  Powerline networks transmit data over power lines as low-frequency radio waves

18. 5 Chapter 5: LANs and WLANs18 Ethernet broadcasts  Simultaneously broadcasts data packets to all network devices (a star topology) –IEEE 802.3 defines the Ethernet protocol –CSMA/CD –CSMA/CD protocol used to share the channel  Vary in speed from 10Mbps to 10Gbps

19. 5 Chapter 5: LANs and WLANs19 Ethernet collision 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. resent That data must be resent.

20. 5 Chapter 5: LANs and WLANs20 Ethernet Equipment Checking a workstation for an Ethernet port

21. 5 Chapter 5: LANs and WLANs21 Ethernet Equipment  Ethernet adapter - NIC (designed to support the Ethernet protocols)  Network hub  Network switch  Network router  RJ45 connector

22. 5 Chapter 5: LANs and WLANs22 Typical Ethernet Setup Technically, this device functions as an Ethernet switch, as well as an IP router.

23. 5 Chapter 5: LANs and WLANs23 Ethernet Setup

24. 5 Chapter 5: LANs and WLANs24 Ethernet Setup  The Network Connection window helps you check your connection

25. 5 SECTION C Chapter 5: LANs and WLANs25 Wireless Networks  Wireless Basics  Bluetooth  Wi-Fi  Wi-Fi Equipment  Wi-Fi Setup

26. 5 Chapter 5: LANs and WLANs26 Wireless Basics without cables or wires  A wireless network transports data from one device to another without cables or wires –RF –RF signals Transceiver –Microwaves –Infrared light  Slower  Slower than wired networks  Security  Security concerns

27. 5 Chapter 5: LANs and WLANs27 Bluetooth connections between electronic devices  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 (a piconet)

28. 5 Chapter 5: LANs and WLANs28 Wi-Fi compatible with Ethernet (per IEEE 802.11)  Wireless networking technologies that are compatible with Ethernet (per IEEE 802.11)  MIMO technology  MIMO technology uses two or more antennae to send multiple sets of signals

29. 5 Chapter 5: LANs and WLANs29 Wi-Fi Equipment

30. 5 Chapter 5: LANs and WLANs30 Wi-Fi Equipment  If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi card

31. 5 Chapter 5: LANs and WLANs31 Wi-Fi Equipment  Wireless network setups ad-hoc network –Wireless ad-hoc network infrastructure network –Wireless infrastructure network Wireless access point Wireless router

32. 5 Chapter 5: LANs and WLANs32 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

33. 5 Chapter 5: LANs and WLANs33 Wi-Fi Setup SSID  Enter an SSID for the network create an encryption key(!!)  Activate WEP, WPA, or WPA2 and create an encryption key(!!)  Set up the wireless workstations Internet access device  Connect an Internet access device modem –Generally a modem that will connect to the service available in your area (cable, DSL, etc.) from your service provider (ISP)

34. 5 Chapter 5: LANs and WLANs34 Typical Wi-Fi Setup

35. 5 Chapter 5: LANs and WLANs35 Wi-Fi Setup Change the default password for your router when you install a wireless network.

36. 5 SECTION D Chapter 5: LANs and WLANs36 Using LANs  LAN Advantages and Challenges  Sharing Files  Sharing Printers  LAN Parties  Troubleshooting

37. 5 Chapter 5: LANs and WLANs37 LAN Advantages  LANs enable people to work together  Sharingsoftware  Sharing networked software can reduce costs  Sharing data  Sharing data on a LAN can increase productivity  Sharinghardware  Sharing networked hardware can reduce costs  Sharing specialized peripheral devices  Sharing networked hardware can provide access to a wide range of services and specialized peripheral devices (read “expensive”)

38. 5 Chapter 5: LANs and WLANs38 LAN Challenges network malfunctions  Resources become unavailable when network malfunctions unauthorized access  Networks may be vulnerable to unauthorized access –More vulnerable than standalone computers  Wireless networks can be tapped from a “snooping” computer susceptible  Networked computers are susceptible to an increasing number of worms, Trojan horses, and blended threats

39. 5 Chapter 5: LANs and WLANs39 Sharing Files automatically detects  If you use Windows, it automatically detects available LANs any time you turn on a workstation shared resource  To connect to a shared resource, you might be asked for a user ID and password

40. 5 Chapter 5: LANs and WLANs40 Sharing Files In this drive mapping example, a server’s drive C is mapped as drive F just as though it were a drive by 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.

41. 5 Chapter 5: LANs and WLANs41 Sharing Files designate them as shared To allow other network users to access files or folders on your Windows computer, you have to designate them as shared (commonly, via Windows Explorer)

42. 5 Chapter 5: LANs and WLANs42 Sharing Printers  Three setups allow for printer sharing: workstation printer –Set up printer sharing using a workstation printer print server –Set up printer sharing using a print server printer with built-in networking –Install printer with built-in networking

43. 5 Chapter 5: LANs and WLANs43 Sharing Printers  In Windows, use the Printers and Faxes dialog box to allow other users to share the printer attached to your workstation

44. 5 Chapter 5: LANs and WLANs44 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

45. 5 Chapter 5: LANs and WLANs45 Troubleshooting  Network problems can stem from a variety of sources –Cables –Signal strength –Interference –Network devices –Security –Settings

46. 5 SECTION E Chapter 5: LANs and WLANs46 Security Through Encryption  Wi-Fi Security  Encryption

47. 5 Chapter 5: LANs and WLANs47 Wi-Fi Security susceptible to unauthorized access  Wireless networks are much more susceptible to unauthorized access and use by casual users than wired networks  LAN jacking, or war driving, is the practice of intercepting wireless signals by cruising through an area

48. 5 Chapter 5: LANs and WLANs48 Wi-Fi Security  An offshoot of war driving is a gambit called war chalking

49. 5 Chapter 5: LANs and WLANs49 Wi-Fi Security encryption  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

50. 5 Chapter 5: LANs and WLANs50 Wi-Fi Security

51. 5 Chapter 5: LANs and WLANs51 Encryption  Encryption transforms a message so that its contents are hidden (encrypted) from unauthorized readers –Plaintext –Plaintext has not yet been encrypted ciphertext –An encrypted message is referred to as ciphertext  Decryption is the opposite of encryption algorithm –Cryptographic algorithm key –Cryptographic key

52. 5 Chapter 5: LANs and WLANs52 Encryption  Weak vs. strong  Weak vs. strong encryption  AES (Advanced Encryption Standard)  Encryption methods can be broken by the use of expensive, specialized, code-breaking computers –Brute-force –Brute-force method

53. 5 Chapter 5: LANs and WLANs53 Encryption  Public key encryption  Public key encryption (PKE) eliminates key- distribution problem, by using one key to encrypt a message and another key to decrypt the message

54. 5 Chapter 5: LANs and WLANs54 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

55. Chapter 5 Complete LANs and WLANs