1. Other LAN Technologies Chapter 5 Copyright 2003 Prentice-Hall Panko’s Business Data Networks and Telecommunications, 4 th edition

2. 2 Other LAN Technologies Large Ethernet networks Wireless LANs ATM LANS and QoS Legacy LANs Token-Ring Networks 10 Mbps Ethernet co-axial cable LANs

3. 3 Figure 5.1: Multi-Switch Ethernet LAN Switch 2 Switch 1 Switch 3 Port 5 on Switch 1 to Port 3 on Switch 2 Port 7 on Switch 2 to Port 4 on Switch 3 C3-2D-55-3B-A9-4F Switch 2, Port 5 A1-44-D5-1F-AA-4C Switch 1, Port 2 E5-BB-47-21-D3-56 Switch 3, Port 6 D4-55-C4-B6-9F Switch 3, Port 2 B2-CD-13-5B-E4-65 Switch 1, Port 7

4. 4 Switching Table Switch 1 PortStation 2A1-44-D5-1F-AA-4C 7B2-CD-13-5B-E4-65 5C3-2D-55-3B-A9-4F 5D4-47-55-C4-B6-9F 5E5-BB-47-21-D3-56 Figure 5.1: Multi-Switch Ethernet LAN Switch 2 Switch 1 Port 5 on Switch 1 to Port 3 on Switch 2 A1-44-D5-1F-AA-4C Switch 1, Port 2 B2-CD-13-5B-E4-65 Switch 1, Port 7 E5-BB-47-21-D3-56 Switch 3, Port 6

5. 5 Figure 5.1: Multi-Switch Ethernet LAN Switch 2 Switch 1 Switch 3 Port 5 on Switch 1 to Port 3 on Switch 2 Port 7 on Switch 2 to Port 4 on Switch 3 C3-2D-55-3B-A9-4F Switch 2, Port 5 Switching Table Switch 2 PortStation 3A1-44-D5-1F-AA-4C 3B2-CD-13-5B-E4-65 5C3-2D-55-3B-A9-4F 7D4-47-55-C4-B6-9F 7E5-BB-47-21-D3-56 E5-BB-47-21-D3-56 Switch 3, Port 6

6. 6 Figure 5.1: Multi-Switch Ethernet LAN Switch 2 Switch 3 Port 7 on Switch 2 to Port 4 on Switch 3 A1-44-D5-1F-AA-4C Switch 1, Port 2 D4-55-C4-B6-9F Switch 3, Port 2 Switching Table Switch 3 PortStation 4A1-44-D5-1F-AA-4C 4B2-CD-13-5B-E4-65 4C3-2D-55-3B-A9-4F 2D4-47-55-C4-B6-9F 6E5-BB-47-21-D3-56 E5-BB-47-21-D3-56 Switch 3, Port 6

7. 7 Figure 5.2: Hierarchical Ethernet LAN Ethernet Switch F Server Y Server X Client PC1 Only One Possible Path Between Any Two Stations PC Client 2 Ethernet Switch E Ethernet Switch D Ethernet Switch B Ethernet Switch A Ethernet Switch C

8. 8 Figure 5.3: Single Point of Failure in a Switch Hierarchy No Communication Switch 1 Switch 2 Switch 3 Switch Fails A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 C3-2D-55-3B-A9-4F D4-47-55-C4-B6-9F E5-BB-47-21-D3-56

9. 9 Figure C.10: 802.1D Spanning Tree Protocol Switch 1 Switch 2 Switch 3 A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 C3-2D-55-3B-A9-4F D4-47-55-C4-B6-9F E5-BB-47-21-D3-56 Activated Deactivated Normal Operation Loop, but Spanning Tree Protocol Deactivates One Link Module C

10. 10 Figure C.10: 802.1D Spanning Tree Protocol Switch 1 Switch 2 Switch 3 A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 C3-2D-55-3B-A9-4F D4-47-55-C4-B6-9F E5-BB-47-21-D3-56 Deactivated Activated Switch 2 Fails Module C

11. 11 Figure 5.2: Hierarchical Ethernet LAN Core Workgroup Ethernet Switch F Server Y Server X Client PC1 PC Client 2 Workgroup Ethernet Switch E Workgroup Ethernet Switch D Core Ethernet Switch B Core Ethernet Switch A Core Ethernet Switch C

12. 12 Figure 5.4: Workgroup Switches versus Core Switches Connects Typical Port Speeds Switching Matrix Workgroup Switches Client or Server to the Ethernet Network 10/100 Mbps Lower Percentage of Nonblocking* Capacity Core Switches Ethernet Switches to One Another 100 Mbps, Gigabit Ethernet, 10 Gbps Ethernet 80% or More of Nonblocking* Capacity

13. 13 Figure C.8: Switching Matrix with Queue Switch Matrix Input Queue Incoming Signal Outgoing Signal Port 1 Port 2 Port 3 Port 4 Port 5 Port 6 Port 7 Port 8 Module C

14. 14 Figure 5.4: Workgroup Switches versus Core Switches Ports = 4 Speed = 1 Gbps Maximum input = 4 Gbps Nonblocking switch matrix capacity = 4 Gbps 1 Gbps Switching Matrix 4Gbps Nonblocking

15. 15 Client A Client B Client C Server DServer E Server Broadcast Figure 5.5: Virtual LAN with Ethernet Switches Server Broadcasting without VLANS Frame is Broadcast Goes to all stations Creates congestion

16. 16 Figure 5.5: Virtual LAN with Ethernet Switches Server Multicasting with VLANS Client A on VLAN1 Client B on VLAN2 Client C on VLAN1 Server D on VLAN2 Server E on VLAN1 Server Broadcast VLANs are collections of servers and their clients Multicasting (some), not Broadcasting (all)

17. 17 Figure 5.6: Tagged Ethernet Frame Destination Address (6 Octets) Destination Address (6 Octets) Source Address (6 Octets) Length (2 Octets) Length of Data Field in Octets 1,500 (Decimal) Maximum Tag Protocol ID (2 Octets) 1000000100000000 81-00 hex; 33,024 decimal Larger than 1,500, So not A Length By looking at the value in the 2 octets after the addresses, the switch can tell if this frame is basic (value less than 1,500) or tagged (value is 33,024) Basic 802.3 MAC FrameTagged 802.3 MAC Frame Start of Frame Delimiter (1 Octet) Preamble (7 octets) Start of Frame Delimiter (1 Octet) Preamble (7 octets) Source Address (6 Octets)

18. 18 Figure 5.6: Tagged Ethernet Frame Tag Control Information (2 Octets) Priority Level (0-7) (3 bits); VLAN ID (12 bits) (1 other bit) Basic 802.3 MAC FrameTagged 802.3 MAC Frame Length (2 Octets) Data Field (variable) PAD (If Needed) Frame Check Sequence (4 Octets) Frame Check Sequence (4 Octets)

19. 19 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length UTP 10Base-T 100Base-TX 10 Mbps 100 Mbps 100 meters Medium 4-pair Category 3, 4, or 5 4-pair Category 5 1000Base-T1,000 Mbps100 meters 4-pair Category 5, 4-pair Enhanced Category 5 is preferred

20. 20 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length Optical Fiber Medium 10Base-F*10 MbpsUP to 2 km* 62.5/125 micron multimode, 850 nm. 100Base-FX100 Mbps412 m 62.5/125 multimode, 1,300 nm, hub 100 Base-FX100 Mbps2 km 62.5/125 multimode, 1,300 nm, switch * Several 10 Mbps fiber standards were defined in 10Base-F.

21. 21 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length Optical Fiber Medium 1000Base-SX1 Gbps220-275 m 62.5/125 micron multimode, 850 nm. 1000Base-LX1 Gbps550 m 62.5/125 micron multimode, 1,300 nm. 1000Base-LX1 Gbps5 km 9/125 micron single mode, 1,300 nm. Longer wavelength, longer distance (850, 1300, 1550 nm) Single mode signals travel farther, but single mode is more expensive

22. 22 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length Optical Fiber Medium 10GBase-SR/SX10 Gbps65 m LAN*** multimode (850 nm) 10GBase-LX410 Gbps300 m LAN*** multimode 1310 nm, wave division multiplexing ***These descriptions are preliminary. LAN versions transmit at 10 Gbps. WAN versions transmit at 9.6 for carriage over SONET links (see Chapter 6). 10GBase-LR/LW10 Gbps10 km LAN*** Single-mode, 1310 nm

23. 23 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length Optical Fiber Medium 10GBase-ER/EW10 Gbps40 km LAN*** Single mode, 1550 nm 40 Gbps Ethernet40 Gbps?Single-mode fiber.**** **** 40 Gbps Ethernet standards are still under preliminary development.

24. 24 Figure 5.7: Ethernet Physical Layer Standards Physical Layer Standard Speed Maximum Run Length Medium Co-Axial Cable 10Base510 Mbps500 metersThick co-axial cable10Base210 Mbps185 metersThin co-axial cable These are Legacy technologies that only operate at 10 Mbps However, you will still encounter them in the field We will see them at the end of this chapter

25. 25 Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points Switch Client PC Server Large Wired LAN Access Point A Access Point B UTPRadio Link Handoff If mobile computer moves to another access point, it switches service to that access point Laptop CSMA/CA+ACK

26. 26 Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points Wireless Notebook NIC Access Point Industry Standard Coffee Cup To Ethernet Switch

27. 27 Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points D-Link Wireless Access Point Using Two Antennas Reduces Multipath Interference (See Ch. 3)

28. 28 Linksys Switch With Built-In Wireless Access Point Using Two Antennas Reduces Multipath Interference (See Ch. 3) Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points

29. 29 Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points The Wireless Station sends an 802.11 frame to a server via the access point The access point converts the 802.11 frame into an 802.3 Ethernet frame and sends the frame to the server Mobile Station Access Point Ethernet Switch Server 802.11 Frame 802.3 Frame

30. 30 Figure 5.8: Typical 802.11 Wireless LAN Operation with Access Points The server responds, sending an 802.3 frame to the access point The access point converts the 802.3 frame into an 802.11 frame and sends the frame to the mobile station. Mobile Station Access Point Ethernet Switch Server 802.11 Frame 802.3 Frame

31. 31 802.11 Wireless LAN Speeds 802.112 Mbps (rare) 2.4 GHz band (limited in bandwidth) 802.11b11 Mbps, 2.4 GHz 3 channels/access point 802.11a54 Mbps, 5 GHz (greater bandwidth) 11 channels/access point 802.11g54 Mbps, 2.4 GHz limited bandwidth

32. 32 Figure 5.9: CSMA/CA + ACK in 802.11 Wireless LANs CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) Station or access point sender listens for traffic If there is no traffic, can send if there has been no traffic for a specified amount of time If the specified amount of time has not been met, must wait for the specified amount of time. Can send if the line is still clear Correction

33. 33 Figure 5.9: CSMA/CA + ACK in 802.11 Wireless LANs CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) Station or access point sender listens for traffic If there is traffic, the sender must wait until traffic stops The sender must then set a random timer and must wait while the timer is running If there is no traffic when the station or access point finishes the wait, it may send Correction

34. 34 Figure 5.9: CSMA/CA + ACK in 802.11 Wireless LANs ACK (Acknowledgement) Receiver immediately sends back an acknowledgement; no waiting because ACKs have highest priority If sender does not receive the acknowledgement, retransmits using CSMA/CA

35. 35 Who Implements CSMA/CA? Stations (when they send) Access Points (when they send) Mobile Station Access Point 802.11 Frame CSMA/CA+ACK

36. 36 Ad Hoc 802.11 Networks No Access Point Stations broadcast to one another directly Not scalable but can be useful for SOHO use NICs automatically come up in ad hoc mode Module C

37. 37 Wired Core / Wireless to the Desktop Normal Networks: Core & Workgroup Switches Core Workgroup Ethernet Switch F Workgroup Ethernet Switch D Core Ethernet Switch B Core Ethernet Switch A Core Ethernet Switch C Workgroup Switches Attach to Stations Module C

38. 38 Wired Core / Wireless to the Desktop With High-Speed Wireless LANs, Replace Workgroup Switches with Access Points Core Access Point 2 Access Point 1 Core Ethernet Switch B Core Ethernet Switch A Core Ethernet Switch C Access Points Serve Stations Module C

39. 39 Wired Core / Wireless to the Desktop Avoids Cost of Running Wires to the Desktop Avoids Costs of Subsequent Changes Only Useful for 802.11a 802.11b and 802.1g lack the bandwidth to serve many users Still Uses a Wired Core To connect to remaining wired desktop devices Probably cheaper than a wireless core Module C

40. 40 Personal Area Networks (PANs) Connect Devices On or Near a Single User’s Desk PC Printer PDA Notebook Computer Cellphone The Goal is Cable Elimination

41. 41 Personal Area Networks (PANs) Connect Devices On or Near a Single User’s Body Notebook Computer Printer PDA Cellphone The Goal is Cable Elimination

42. 42 Personal Area Networks (PANs) There May be Multiple PANs in an Area May overlap Also called piconets

43. 43 Figure 5.10: 802.11 versus Bluetooth LANs Focus Speed 802.11Bluetooth Local Area NetworkPersonal Area Network 11 Mbps to 54 Mbps In both directions 722 kbps with back channel of 56 kbps. May increase. Distance 100 meters for 802.11b (but shorter in reality) Number of Devices Limited in practice only by bandwidth and traffic 10 piconets, each with up to 8 devices 10 meters (may increase)

44. 44 Figure 5.10: 802.11 versus Bluetooth LANs Scalability Cost Battery Drain 802.11Bluetooth Good through having multiple access points Poor (but may get access points) Probably higherProbably Lower HigherLower DiscoveryNoYes Discovery allows devices to figure out how to work together automatically

45. 45 Figure 5.11: Bluetooth Operation File Synchronization Client PC Slave Notebook Master Printer Slave Printing Cellphone Telephone Piconet 1

46. 46 Figure 5.11: Bluetooth Operation Client PC Notebook Printer Slave Printing Call Through Company Phone System Cellphone Master Telephone Slave Piconet 2

47. 47 Figure 5.11: Bluetooth Operation File Synchronization Client PC Slave Notebook Master Printer Slave Printing Call Through Company Phone System Cellphone Master Telephone Slave Piconet 1 Piconet 2

48. 48 Figure 5.12: Normal Radio Transmission and Spread Spectrum Transmission Channel Bandwidth Required for Signal Normal Radio: Actual Bandwidth Used Note: Height of Box Indicates Bandwidth of Channel

49. 49 Figure 5.12: Normal Radio Transmission and Spread Spectrum Transmission Channel Bandwidth Required for Signal Frequency Hopping Spread Spectrum (FHSS) 802.11 Direct Sequence Spread Spectrum (DSSS) 802.11b Note: Height of Box Indicates Bandwidth of Channel Wideband but Low-Intensity Signal

50. 50 Figure 5.13: Code Division Multiple Access (CDMA) Spread Spectrum Transmission Client PC 1 Client PC 2 Low-Density Orthogonal Signal 1 Low-Density Orthogonal Signal 2 Server A Server B Radio Spectrum Used in Some Cellular Telephone Systems

51. 51 OFDM Orthogonal Frequency Division Multiplexing Divide a large channel into many subchannels Send part of the signal in each channel Do not use channels with impairment 802.11a, 802.11g at 54 Mbps New Channel Subchannel Unused Subchannel

52. 52 Spread Spectrum Methods Spread Spectrum Techniques DSSSFHSS 802.11 DSSS CDMA OFDM

53. 53 Ultrawideband (UWB) Extreme spread spectrum transmission Signal spread over 25% above and below the central carrier frequency or at least 1.5 GHz If carrier is at 1 GHz, signal spreads between 500 MHz and 1.5 GHz Much wider than traditional spread spectrum channels New Not in Book

54. 54 Ultrawideband (UWB) Why UWB? High transmission rate despite very low power Very low power makes signals difficult to detect for security Multipath interference and interference are unimportant Can travel through thick walls In fact, used in ground-penetrating radar New Not in Book

55. 55 Ultrawideband (UWB) Problems Bandwidth usually cuts across multiple licensed and unlicensed service bands Potential for interference with existing services Power per hertz is so low that existing services should only perceive a slight increase in noise when USB is used Still, concern over low-power services such as GPS, so government approval is limited New Not in Book

56. 56 ATM Ethernet competitor for switched LANs Quality of Service (QoS) for telephony and multimedia transmissions Highly scalable in size (number of stations) Highly complex and expensive Not selling well for LANs Increasingly popular for WANs

57. 57 Figure 5.14: ATM versus Ethernet LANs Ethernet LANsATM LANs Designed forLANs Worldwide Telephone Network ComplexityLowHigh Equipment CostLowHigh Management CostLowHigh Scalable in SpeedHigh QoS Guarantees None, but Overprovisioning and Priority make Ethernet competitive even for latency-intolerant applications Excellent for Voice Usually not good for data

58. 58 Figure 5.15: Handling Brief Traffic Peaks Traffic Network Capacity Peak Load: Congestion and Latency Time Congestion and Latency

59. 59 Figure 5.15: Handling Brief Traffic Peaks Traffic Network Capacity Peak Load Time Quality of Service (QoS) Guarantees in ATM Traffic with Reserved Capacity Always Goes (Voice) Other Traffic Must Wait (Data)

60. 60 Figure 5.15: Handling Brief Traffic Peaks Traffic Overprovisioned Network Capacity Peak Load: No Congestion Time Overprovisioned Traffic Capacity in Ethernet

61. 61 Figure 5.15: Handling Brief Traffic Peaks Traffic Network Capacity Peak Load Time Priority in Ethernet High-Priority Traffic First Low-Priority Waits

62. 62 Figure 5.16: ATM Network with Virtual Circuits Server Client PC ATM Switch 1 ATM Switch 2 ATM Switch 3 ATM Switch 4 ATM Switch 5 Virtual Circuit Virtual Circuit ATM switches can be arranged in a Hierarchy, so there are multiple Alternative routes. This makes Switching slow

63. 63 Figure 5.16: ATM Network with Virtual Circuits Server Client PC ATM Switch 1 ATM Switch 2 ATM Switch 3 ATM Switch 4 ATM Switch 5 Virtual Circuit Virtual Circuit ATM selects a single route, called a Virtual circuit, before two stations Begin transmitting. This simplifies Switching and so lowers switching cost

64. 64 Figure 5.16: ATM Network with Virtual Circuits Server Client PC ATM Switch 1 ATM Switch 2 ATM Switch 3 ATM Switch 4 ATM Switch 5 Virtual Circuit Virtual Circuit Virtual Circuit A... B... C... D... Port 1 2 3 4 Switch 4 Switching Table ATM switching tables are as simple as Ethernet switching tables

65. 65 ATM Reduces Switching Costs Virtual circuits simplify switching, reducing switching costs. ATM is unreliable, also reducing switching costs

66. 66 Figure 5.17: Virtual Circuit with VPI and VCI Virtual Path is a Path to a Site Virtual Channel is a Connection to a Particular Computer at the Site Switches in Backbone Only Have to Look at the Virtual Path Indicator (VPI) Virtual Channels Virtual Path Site 1 Site 2 ATM Backbone

67. 67 Figure 5.17: ATM Cell Bit 1Bit 4Bit 3Bit 2Bit 8Bit 7Bit 6Bit 5 Virtual Channel Identifier Virtual Path IdentifierVirtual Channel Identifier Reserved Call Loss Priority Payload Type Header Error Check Payload (48 Octets) Virtual Path Identifier VPI: Specifies a VC to site VCI: Specifies a station at site Switches between sites only look at VPI 5 octets of header 48 octets of payload 53 octets total

68. 68 ATM Cells ATM frames are short and fixed in length; called cells Only 53 octets long 5 octets of header 48 octets of data Reduces latency at switches Switch may have to wait until entire frame arrives before sending it back out--faster with short cells Fixed length gives predictability for faster processing

69. Token-Ring Networks Legacy LAN Technologies

70. 70 Token-Ring Networks Ring Topology Inner Ring Outer Ring Frame Normal Operation Dual Ring; normally only one is used

71. 71 Token-Ring Networks Ring is wrapped if there is a break The wrapped ring is still a full ring Break Wrapped Ring

72. 72 Token-Ring Networks Special Frame Called Token Circulates when no station is transmitting For access control, station must have token to send Inner Ring Outer Ring Token

73. 73 Figure 5.19: 802.5 Token-Ring Network STP or UTP Break Wrapped Ring

74. 74 Figure 5.18: Major Legacy Networks Token-Ring Networks 802.5 Token-Ring Networks 4 Mbps initially, soon reached 16 Mbps More expensive than Ethernet; has largely died in the market Still seen in some legacy networks, especially among IBM mainframe users Uses 2-pair shielded twisted pair to reduce EMI Metal mesh around each pair Metal mesh around jacket

75. 75 Figure 5.18: Major Legacy Networks Token-Ring Networks FDDI (Fiber Distributed Data Interface) 100 Mbps 200 km circumference is possible (MANs) Had niche in LAN cores (far and fast) Losing out to faster gigabit Ethernet Campus Building FDDI LAN Ring (200 km maximum circumference)

76. 76 Figure 5.18: Major Legacy Networks Early Ethernet Standards General Before switches and hubs Only 10 Mbps Used coaxial cable

77. 77 Figure 5.18: Major Legacy Networks Early Ethernet Standards 10Base5 Multidrop topology Thick trunk cable uses coaxial cable technology; 500-meter limit Drop cable has 15 wires 15-hole Attachment Unit Interface (AUI) connector Trunk Cable Drop Cable 15-Hole AUI Port

78. 78 Figure 5.18: Major Legacy Networks Early Ethernet Standards 10Base2 Daisy chain topology Thin coaxial cable between stations Circular BNC connector

79. 79 Figure 5.18: Major Legacy Networks Ethernet 10Base2 To Next Station

80. 80 Figure 5.18: Major Legacy Networks Ethernet 10Base2: UTP vs BNC Connectors RJ-45 UTP Connectors BNC Connector 10Base2 T-Connector UTP Thin Coax

81. 81 Figure 5.18: Major Legacy Networks Ethernet 10Base2 BNC Connector T-Connector To Next Station