Wireless Bridges: Connecting LANs for Improved Connectivity

1. IFIP-UNU ADVANCED COURSE ON NETWORKING AND SECURITYModule II-Wireless CommunicationsSection 6 Bridges

2. Overview This chapter discusses wireless bridges as a means of connecting LANs. Bridges are used to connect two or more wired LANs to create one large LAN.

3. Learning Objectives • Determine the feasibility of installing a wireless bridge link. • Explain why a wireless bridge may be a better solution than other alternatives. • Determine the maximum distance that can be achieved using wireless bridges with given antennas and extension cables. • Identify steps necessary to protect a wireless bridge installation against a lightning strike.

4. Key Terms • Root bridge • Non-Root bridge with clients • Non-Root bridge without clients • Repeater AP • Root AP • Site-Survey client • Installation mode

5. Bridge Connection

6. Bridging Defined • Bridges are used to connect two or more wired LAN’s, usually located within separate buildings, to create one large LAN.

7. Technology Comparisons Installation Cost Monthly Cost (USD) Barriers to Implement Technology Dialup or 56K Remote locations $0 to $250 $25 to $50 Cable/DSL $0 to $250+ $25 to $150 Reliability E1, T1 $250 to $1,000+ $400 to $1000+ Availability Recurring Cost $5,000 to $200,000+ Physical obstructions Fiber $0 Licensing, Weather Microwave $15,000+ $0 $2,000 to $15,000 802.11 $0 Interference

8. RBOC DS1 DS1 DS3 New remote office - No DS1 connection available Traditional WAN Connectivity Monthly Leased Line OpEx 2 DS1: $600 1 DS3: $5000 TOTAL: $5600 RBOC provides guaranteed level of service via a Service Level Agreement (SLA)

9. RBOC 2 Mbps 2 Mbps 22 Mbps 5 Mbps 802.11b Connectivity Monthly Line Cost 2 DS1: $600 1 Fractional DS3: $3000 TOTAL: $3600 Wireless Installation Cost 7 350 Series Bridges Installed: $12,500 USD Pay Back Period: 3 months New building connected Self managed

10. RBOC 14 Mbps 14 Mbps 50 Mbps 27 Mbps 802.11a Connectivity Monthly Line Cost 2 DS1: $600 1 DS3: $5000 TOTAL: $5600 Wireless Installation Cost 7 1400 Series Bridges Installed: $40,000 USD Pay Back Period: 8 months New building connected Self managed

11. Role in Radio Network • Role in Radio Network • Determines functionality within WLAN • Determines which type of clients will be supported File Server Bridge Workgroup Bridge Bridge Access Point PCI Card PC Card

12. Introduction • The BR350 is sometimes called the multifunction bridge.

13. Bridges • Cisco bridges can be controlled and configured though command line and Web interfaces. • Management can also be done through traditional protocols like SNMP.

14. Bridge roles in the network • The Cisco bridges can be configured to operate in different modes. • The BR350, or multifunction bridge, has the same receiver sensitivity, power levels, and capabilities, as the Cisco Aironet APs with .11b radio chips.

15. Parent-Child Relationship: Root - Non-Root

16. Bridge roles in the network • Root Access Point—Use this setting to set up the bridge as a rugged access point connected to the wired LAN. When you select Access Point, the bridge's Spanning Tree Protocol (STP) function is disabled. Root Access Point

17. Bridge roles in the network • Root bridge—One bridge in each group of bridges must be set as the root bridge. A root bridge can only communicate with non-root bridges and other client devices and cannot associate with another root bridge. Root Bridge

18. Bridge roles in the network • Non-Root Bridge w/Clients—Use this setting for non-root bridges that will accept associations from client devices, and for bridges acting as repeaters. Non-root bridges can communicate with other non-root bridges, root bridges, and client devices. Non-Root Bridge with Clients

19. Bridge roles in the network • Non-Root Bridge w/o Clients—Use this setting for non-root bridges that should not accept associations from client devices. A bridge set to Non-Root Bridge w/o Clients will only communicate with a root or non-root bridge. Non-Root Bridge without Clients

20. Bridge roles in the network • Repeater Access Point—Use this setting to set up the bridge as a rugged repeater access point. A repeater access point is not connected to the wired LAN; it is placed within radio range of an access point connected to the wired LAN to extend the range of your infrastructure or to overcome an obstacle that blocks radio communication. When you select Repeater Access Point, the bridge's STP function is disabled. Repeater Access Point

21. Power Options

22. Distances Limited by 802.11 Specification

23. BR350—Front Cover LED’s

24. Bridge Model BR350 802.11b Bridge Standard Cable (6.7 dB/100 ft. loss) (6.7 dB/30.5 m) Data Rate Max. Distance Miles Km Optional Antenna 11 Mbps 20.5 33.0 21 dBi Dish 50 ft (15.2m)/side 11 Mbps 32.7 52.5 21 dBi Dish 20 ft (6.1m)/side 5.5 Mbps 32.6 52.4 21 dBi Dish 50 ft (15.2m)/side 2 Mbps 41.0 66.0 21 dBi Dish 50 ft (15.2m)/side 1 Mbps 51.7 83.2 21 dBi Dish 50 ft (15.2m)/side Note: Distances over 25 miles or 40 Km are very hard to align and install!

25. 802.11b Common Questions Cisco Aironet Bridge How Fast? 2 Mbps Max data rate 11 Mbps Typical throughput 5.5 Mbps 1.4 Mbps How Far? 3.6 Miles 5.8 Km 7.3 miles 11.7 Km Yagi antenna 20.5 Miles 33 Km 25+ miles 40+ Km Dish antenna Note: All distances may be limited by governing bodies and standards.

26. Optional 2.4GHz Antennas for Long Range • 13.5 dBi Yagi • Distances over • 7.3 miles @ 2 Mbps • 11.7 Km @ 2 Mbps • 3.6 miles @ 11 Mbps • 5.8 Km @ 11 Mbps • 21 dBi Solid Dish • For distances up to • 25+ miles @ 2 Mbps • 40+ Km @ 2 Mbps • 20.5 miles @ 11 Mbps • 33 Km @ 11 Mbps Note: Distances include 50 feet of low loss cable and 10 dB fade margin

27. Richardson Elementary Yagi Weaver- Special Education Dish Roberts Middle School Dish High School 2 Bridges One 12 dBi omni One Dish Administration 2 Bridges One 12 dBi omni One Yagi Channel #1 Channel #6 Bolich Middle School Yagi Channel #11 Price Elementary Yagi Dewitt Elementary Yagi 802.11b Bridge Application: School District Bode Elementary Yagi Lincoln Elementary Yagi

28. Lightning

29. Lightning Arrestor • Designed to protect LAN devices from static electricity and lightning surges that travel on coax transmission lines • RP-TNC connectors used on all Cisco Antennas To Antenna Lug Lockwasher Nut Ground Wire From RF Device

30. Direct Strike Protection

31. Coax Connection Sealing • Number one problems with bridges - water in the connectors • Proper sealing is important • Coax Seal is one product that is inexpensive and works great

32. Path Loss Considerations The following are needed to determine coverage ·         Antenna Gain ·         Transmitter Power ·         Receiver Performance ·         Cable Losses ·         Environmental Structures

33. Calculations of Coverage Performance Coax Length 100 ft (30.5 m)? Towers needed to clear trees and other buildings Coax Length 150 ft (45.7)? Wants 11 Mbps data rate Distance = 13 miles (20.9 Km)

34. LED indicators • When the bridge is powering on, all three LEDs normally blink. • After bootup, the colors of the LEDs represent the following: • Green LEDs indicate normal activity. • Amber LEDs indicate errors or warnings. • Red LEDs mean the unit is not operating correctly or is being upgraded.

35. Connecting to the Bridge • There are 3 basic GUI interfaces depending on the bridge image: • IOS 1400 • VxWorks BR350 • SOS WGB350

36. 1400 with IOS GUI

37. BR350 with VxWorks GUI

38. WGB350 with SOS GUI ad SOS Menu

39. Resetting the Bridge • Resetting the Cisco bridges depends on the model. • The BR350, can be reset via the console, telnet, or browser connection. • If the password is unknown, then the console reset method is required. • The console port on the BR350. • The :resetall command can be used after rebooting the bridge, however the command must be entered within 2 minutes of rebooting. • The 350 Series Workgroup Bridge or the 1400 series bridge can be reset to default values via the Reset button, telnet, or browser connection.

40. Default Settings for BR350 and 1400

41. Default Settings for WGB 350

42. Basic Configuration

43. BR350 Home Page (Summary Status)

44. BR350 Map Link • The Map link opens the Map window, which contains links to every management page. • The Map window can be used to jump quickly to any system management page, or to a map of the entire wireless network

45. BR350 Network Link

46. BR350 Associations Link

47. BR350 Setup Link • The Setup link displays the Setup page, which contains links to the management pages with configuration settings.

48. BR350 Logs Link

49. BR350 - Basic Configuration • Connect just like an AP, suggest wired GUI. • Remember to set the IP address on your Ethernet NIC.

50. Root Bridge and Non-Root Bridges