1. IFIP-UNU ADVANCED COURSE ON NETWORKING AND SECURITY Module II-Wireless Communications Section 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
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. 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)
RBOC
DS3
DS1
New remote office
- No DS1 connection available

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

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

11. Role in Radio Network File Server Bridge Role in Radio Network
Determines functionality within WLAN
Determines which type of clients will be supported
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
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.

17. Bridge roles in the network
Root Bridge
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.

18. Bridge roles in the network
Non-Root Bridge with Clients
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.

19. Bridge roles in the network
Non-Root Bridge without Clients
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.

20. Bridge roles in the network
Repeater Access Point
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.

21. Power Options

22. Distances Limited by 802.11 Specification

23. BR350—Front Cover LED’s

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

25. Note: All distances may be limited by governing bodies and standards.
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 2 Mbps
Mbps
Mbps
Mbps
21 dBi Solid Dish
For distances up to
25+ miles @ 2 Mbps
40+ 2 Mbps
Mbps
33 11 Mbps
Note: Distances include 50 feet of low loss cable and 10 dB fade margin

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

51. Non-Root Bridge without Clients Repeater Bridge

52. Bridge as Root Access Point

53. Bridge as Repeater Access Point

54. Root Radio Identification configuration
The current IP subnet mask displayed under the setting shows the IP subnet mask currently assigned to the bridge. This is the same subnet mask as the default subnet mask unless DHCP or BOOTP is enabled. If DHCP or BOOTP is enabled, this is the subnet mask used by the DHCP or BOOTP server.
You can also enter this setting on the Express Setup page.

55. Root Radio Identification Page
Primary Port Settings: Two options allow for the designation of the radio port as the primary port on the bridge:
Primary Port? The primary port determines the MAC and IP addresses of the bridge.
The default primary port of the bridge is the Ethernet port.
The Ethernet port is connected to the wired LAN, so this setting is usually set to no.
Select no to set the Ethernet port as the primary port.
Select yes to set the radio port as the primary port.
Adopt Primary Port Identity?
Select yes, to adopt the primary port MAC and IP addresses for the radio port.
Select no to use different MAC and IP addresses for the radio port. Bridges acting as root units adopt the primary port settings for the radio port.
When putting a bridge in standby mode, select no for this setting.

56. Root Radio Hardware configuration
Similar to an AP.

57. Root Radio Hardware configuration

58. Ethernet Identification configuration
Addressing is similar to Root Radio options

59. Ethernet Hardware configuration

60. Ethernet Hardware configuration

61. Configuring time services

62. Configuring boot services

63. Configuring name services

64. Configuring routing services

65. Configuring routing services
Manage Installation Keys is used to read specifications of the software license and to install a new license.
Manage System Configuration is used to restart the device, download a configuration file, or reset settings to factory defaults.
Distribute Configuration to other Cisco Devices is used to send the configuration of the device to other Cisco Aironet devices on the network.
Distribute Firmware to other Cisco Devices is used to send a new firmware version to other Cisco Aironet devices on the network.

66. CDP

67. Distribute Firmware to Other Cisco Devices

68. Hot Standby Management

69. 1400 Series Bridge
801.11a wireless bridge

70. Overview
The Cisco Aironet 1400 Series Wireless Bridge is a high-performance a wireless bridge designed to connect multiple LANs in a metropolitan area.
Designed to be a cost-effective alternative to leased lines, it is engineered specifically for harsh outdoor environments . The features of the 1400 include:

71. Overview
Support for both point-to-point or point-to-multipoint configurations
Support data rates up to 54 Mbps
Enhanced security mechanisms based on i standards
Rugged enclosure optimized for harsh outdoor environments with extended operating temperature range
Integrated or optional external antennas for flexibility in deployment

72. Overview
Data rates of 54 Mbps can be enabled for point-to-point links up to 7.5 miles, and for point-to-multipoint links up to 2 miles.
Aggregate throughput can be obtained in excess of 28 Mbps.
Also, by using higher gain antennas or lower data rates, ranges in excess of 20 miles point-to-point can be covered.

73. Models and options
There are two options for ordering the Cisco Aironet 1400 Series Wireless Bridge:
Cisco Aironet 1410 Wireless Bridge with 22.5 dBi Antenna, FCC Config
Cisco Aironet 1410 Wireless Bridge with N-Type Connector, FCC Config

74. Models and options

75. Components and accessories
Cisco Aironet Power Injector
Mounting Kit

76. IOS features

77. 802.11a Bridge 1400 Bridge Model Data Rate Max. Distance Miles Km
Optional Antenna
54 Mbps
xx.0
28 dBi Dish
9 Mbps xx
28 dBi Dish
54 Mbps xx
22 dBi Int.
16 Mbps xx
22 dBi Int.
Note: Distances over 25 miles or 40 Km are very hard to align and install!

78. Optional 5GHz Antennas for Long Range
9.5 dBi sector (H or V polarization)
Network configurations
Point to point
Point to multi-point
Roof, pole, and wall mounting options
5.8 GHz Unlicensed Band Operation
Rapid deployment and re-commissioning
Operating temp range: -30 to +55 oC
Humidity: 0 to 100%
9 dBi omni (Vertical polarization)
28 dBi dish (H or V polarization)

79. Labs

80. Labs of Section 6 Lab 6.3.6 Configure Site-to-Site Wireless Link
Lab Configure Bridge Services
Lab Manage Bridge Configuration and Image Files