Cisco WLAN - Chapter. 06 : bridges

Ch. 6 - Bridges
Cisco Fundamentals of Wireless LANs version 1.1
Rick Graziani
Cabrillo College

Rick Graziani graziani@cabrillo.edu 2
Overview
• Designed to connect two or more networks, typically located in different
buildings, wireless bridges deliver high data rates and superior
throughput for data-intensive, line-of-sight applications.
• The bridges connect hard-to-wire sites, noncontiguous floors, satellite
offices, school or corporate campus settings, temporary networks, and
warehouses.
• The high-speed links between the wireless bridges deliver throughput
many times faster than E1/T1 lines for a fraction of the cost, thus
eliminating the need for expensive leased lines or difficult-to-install
fiber-optic cable.
802.11a

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

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

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
DS1
New remote office
- No DS1 connection
available
Traditional WAN 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
RBOC
22 Mbps
2 Mbps
2 Mbps
5 Mbps
802.11b 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
RBOC
50 Mbps
14 Mbps
14 Mbps
27 Mbps
802.11a Connectivity

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

Introduction
• The BR350 is sometimes called the multifunction bridge.

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

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.

Parent-Child Relationship: Root - Non-Root

• 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

• 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

• 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

• 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

• 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

Power Options

Distances Limited by
802.11 Specification

BR350—Front Cover LED’s

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

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

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

802.11b Bridge Application: School District
Lincoln
Elementary
Yagi
Bode
Elementary
Yagi
Richardson
Elementary
Yagi
Price
Elementary
Yagi
Dewitt Elementary
Yagi
Bolich
Middle
School
Yagi
Roberts
Middle School
Dish
Weaver-
Special
Education
Dish
High School 2
Bridges
One 12 dBi omni
One Dish Administration
2 Bridges
One 12 dBi omni
One Yagi
U N I V E R S I T Y
U N I V E R S I T Y
Channel #11
Channel #6
Channel #1

Lightning

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
Ground Wire
From RF Device
Lug
Lockwasher
Nut

Direct Strike Protection

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

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

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

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.

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

1400 with IOS GUI

BR350 with VxWorks GUI

WGB350 with SOS GUI ad SOS Menu

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.

Default Settings for BR350 and 1400

Default Settings for WGB 350

Basic Configuration
Will will not use or discuss all of the configuration
options and features.

BR350 Home Page (Summary Status)

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

BR350 Network Link

BR350 Associations Link

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

BR350 Logs Link

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

Root Bridge and Non-Root Bridges

Non-Root Bridge without Clients
Repeater Bridge

Bridge as Root Access Point

Bridge as Repeater Access Point

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.

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.

Root Radio Hardware configuration
• Similar to an AP.

Root Radio Hardware configuration

Ethernet Identification configuration
• Addressing is similar to Root Radio options

Ethernet Hardware configuration

Configuring time services

Configuring boot services

Configuring name services

Configuring routing services

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.

CDP

Distribute Firmware to Other Cisco Devices

Hot Standby Management

1400 Series Bridge
801.11a wireless bridge

Overview
• The Cisco Aironet 1400 Series Wireless Bridge is a high-performance
801.11a 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:

Overview
• Support for both point-to-point or point-to-multipoint configurations
• Support data rates up to 54 Mbps
• Enhanced security mechanisms based on 802.11i standards
• Rugged enclosure optimized for harsh outdoor environments with
extended operating temperature range
• Integrated or optional external antennas for flexibility in deployment

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.

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

Models and options

Components and accessories
Cisco Aironet Power Injector
Mounting Kit

IOS features

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

Optional 5GHz Antennas for Long Range
• 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 o
C
• Humidity: 0 to 100%
• 9 dBi omni (Vertical
polarization)
• 9.5 dBi sector (H or V
polarization)
• 28 dBi dish (H or V
polarization)

Bridge Range Calculation Utility

Bridge Distance Calculations (cont.)

Cisco WLAN - Chapter. 06 : bridges

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