Ai

Point-to-Point

Point-to-Multipoint

Root

Root

Non-Root

Non-Root Non-Root

© 2003, Cisco Systems, Inc. All rights re

Cisco Aironet Bridges can be configured to operate in many different modes. This is the function of the Role in Radio Network parameter. Note in each scenario there is only one Root Bridge.

Non-Root Bridge without Clients

This mode would be used for a bridge that is used to connect a remote wired LAN and will only communicate with another Root Bridge. In this mode the bridge will refuse associations from wireless clients.

Communicates with:

• Workgroup Bridge

• Repeater Access Points

• Wireless Clients

Workgroup

Repeater

HI

' Bridge

Access Point

NOTE: Unlike the BR350, the BR1410 only arts the Root ar i radio network.

supports the Root and Non-Root Bridge roles in the radi

NOTE: Unlike the BR350, the BR1410 only arts the Root ar i radio network.

© 2003, Cisco Systems, Inc. All rights re

This setting is normally used for the "main" bridge - in other words, the bridge that is connected to the main network. This bridge would be used to provide connectivity to the main LAN for other wireless clients or wired clients that are being connected wirelessly. In this mode the bridge will support the following client types by default:

■ Non-Root Bridges

■ Wireless Client Cards (PC Card, PCI Card)

■ Workgroup Bridges (WGB)

■ Access points configured as Repeaters

Only one bridge in a WLAN can be set as the root bridge. This is the default setting for Cisco Aironet Bridges.

Parent -Child Relationship (Root Bridge vs. Non-Root Bridge)

Cisco.com

Root Bridge (Parent):

• Accepts associations and communicates with Non-Root Bridge (Child) devices

• Will not communicate with other Root Bridge devices

• Communicates with multiple Non-Root bridges

NOTE: Unlike the BR350, the BR1410 only supports the Root and Non-Root Bridge roles in the radio network.

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-18

Unlike Cisco Aironet Access Points, bridges require some configuration prior to installation. A parent-child relationship must be established between bridges before they can communicate. This is the function of the "Root Bridge" mode on Cisco Aironet bridges. A bridge that is configured as a "Root Bridge" device is considered a parent bridge. A bridge that is configured as a "Non-Root Bridge" device is considered a child. The child bridge will learn many of the configurable parameters from the parent bridge.

NOTE: Unlike the BR350, the BR1410 only supports the Root and Non-Root Bridge roles in the radio network.

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-18

Parent -Child Relationship (Root vs. Non-Root)

cIsco~corn

Non-Root (Child):

• Can associate and communicate with Root devices or Clients

• Will not communicate with other Non-Root devices

- Unless other Non-Root device is communicating with a parent

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-19

A single parent bridge can support numerous child bridges. How many child bridges should actually be attached to a parent bridge will be determined by usage and throughput needs.

Only exception: Non-Root Bridge will communicate to another Non-Root Bridge as long as one of the Non-Root Bridges has a Root Bridge in its uplink.

cIsco~corn

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-19

Root Mode: Access Point vs. Bridge

Access Point in Non-Root mode

• Management traffic ONLY via Ethernet

Bridge set to Root or Non-Root

• Able to send traffic via Ethernet or Radio oooooo f

Point in -Root mod

Ige in Rool mode ie in Non-Re mode

© 2GG3, Cisco Systems, Inc. All rights reserved. AWLF v3.1—1-2G

Whether configured as a "Root" or "Non-Root" device, a bridge can always communicate with other bridges via the RF, and the wired network via the Ethernet port. Even when configured to operate in access point mode, the bridge can still pass network traffic via both the RF and Ethernet ports. This is one of the main differences between a Cisco Aironet Bridge and Access Point.

Cisco Aironet Access Points and Bridges use the same radio. The Cisco Aironet Bridge has the same receiver sensitivity, power levels, and capabilities as the Cisco Aironet Access Point. This means that while operating in access point mode, the Cisco Aironet Bridge can be configured as a fully IEEE 802.11 compliant access point that will support Cisco Aironet wireless clients.

Root Bridge

Communicates with:

• Non-Root Repeater Bridges

• Repeater Access Points

• Wireless Clients

Non-Root Bridge

NOTE: Unlike the BR350, the BR1410 only supports the Root and Non-Root Bridge roles in the rad'

i radio network.

© 2003, Cisco Systems, Inc. All rights re

This setting is used for any bridges in the WLAN that will be connecting to a Root bridge. In this mode, a bridge will perform bridging functions (connect to a Root bridge) and will also support the following clients by default:

■ Wireless Clients (PC Card, PCI Card)

■ Workgroup Bridge

■ Access points configured as a Repeater

■ Other Non-Root Bridges

In this mode the bridge may connect to a remote wired LAN or may be used as a repeater bridge. When used as a repeater bridge, the bridge would not be connected to a remote wired LAN and would simply pass traffic from associated wireless clients to another Non-Root bridge or a Root bridge.

In order for wireless clients to attach to a Non-Root bridge, the bridge must be associated with a Root bridge, or another Non-Root bridge that is associated to a Root bridge.

35G Series Bridge Configured as a Repeater Access Point

Connects to

muni- ijisco.com

• Root bridges

• Non-Root bridges

• Root access points

• Other repeater access points

X

Repeaters are not covered by 802.11 standards

NOTE: Unlike the BR350, the BR1410 only supports the Root and Non-Root Bridge roles in the radio network.

© 2003, Cisco Systems, Inc. All rights reserved.

AWLF v3.1—4-22

When in this mode the bridge will operate with the same functionality as a Cisco Aironet Access Point in repeater mode. The bridge will repeat wireless client traffic to any of the following:

■ Access point connected to LAN

■ Another Repeater Access Point

■ Root Bridge connected to LAN

■ Non-Root Bridge connected to LAN

■ Bridge in access point mode connected to LAN

The bridge will only pass management traffic (no WLAN client traffic) via the Ethernet port.

Due to the fact that repeaters are not covered by 802.11 standards non-Cisco clients may or may not work with Cisco repeaters.

350 Series Bridge Configured as a Site Survey Client

Used to survey access point configured as RepeapernAtccess repeater

Will not accept associations from Wireless Clients

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-23

The bridge can be configured as a Site Survey Client for surveying a repeater access point. While in this mode the bridge can connect to another bridge or access point, but will not accept associations from wireless clients. The Site Survey Client can then be used to perform linktests with other bridges or access points.

Installation Considerations

Typical questions for bridges include how far will it go, how fast will it go, and how many users can it support.

How fast: One item that is very deceiving is data rate - what does it really mean? As with the LAN systems, data rate indicates how fast the RF passes data. This RF data includes the radio system overhead, plus the network data. The real item that should be discussed is throughput. This is the actual amount of network data that gets passed from one LAN to another. Remember higher data rates do not mean higher throughput. Some 1.6 Mbps systems achieve as little as 500 Kbps throughput.

With a 2.4 GHz bridge, the data rate can be set to various speeds (1, 2, 5.5, 11 Mbps). Reducing the speed increases the maximum distances that can be obtained. The same concept applies to 5 GHz bridges.

Adding filtering in the configuration can increase actual performance by eliminating unnecessary traffic over the RF. This has the same effect as increasing throughput. How many users the bridge can support is a question of what type of traffic is being handled. Throughput is the real limiting factor.

1400 Series Bridge Range vs. Data Rate

Data rate

6 Mbps

9 Mbps

12 Mbps

18 Mbps

24 Mbps

36 Mbps

48 Mbps

54 Mbps

P2P LOS range (miles) 22.5 dBi captive antennas

15.5

15.3

14.1

13.2

11.8

10.0

8.3

7.8

P2P LOS range (miles) 28 dBi remote antennas

23.4

23.1

21.4

20.0

17.8

15.1

12.6

11.8

P2MP LOS range (miles) 9 dBi external hub ant. 22.5 dBi captive client ant.

8.3

8.2

7.6

7.1

5.7

3.8

2.4

2.0

P2MP LOS range (miles) 9.5 dBi remote hub ant. 22.5 dBi captive client ant

8.5

8.4

7.8

7.2

6.1

4.1

2.6

2.2

P2MP LOS range (miles) 9 dBi remote hub ant. 28 dBi remote client ant.

9.8

9.6

8.9

8.3

7.4

5.7

3.6

3.0

P2MP LOS range (miles) 9.5 dBi remote hub ant. 28 dBi remote client ant.

10.2

10.1

9.3

8.7

7.8

6.4

4.1

3.4

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-26

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-26

The 5.8 GHz radio in the Cisco Aironet 1400 Series offers superior radio performance that results in industry-leading range. The greater the range, the higher the supported data rate or the more reliable the link at a given data rate.

■ Point-to-point range 7.5 miles (13 km) @ 54 Mbps16 miles (26 km) @ 9 Mbps 12 miles (19 km) @ 54 Mbps23 miles (37 km) @ 9 Mbps(Antennas are 28 dBi dish)

■ Point-to-multipoint range (sector antenna at root) 2 miles (3 km) @ 54 Mbps8 miles (13 km) @ 9 Mbps4 miles (7 km) @ 54 Mbps11 miles (18 km) @ 9 Mbps(Non-root antenna is 28 dBi dish)

350 Series Bridge Range vs. Data Rate

Cisco.com

Bridge Model

Data Rate

Max. Distance Miles Km

Optional Antenna

Standard Cable (6.7 dB/100 ft. loss) (6.7 dB/30.5 m)

11 Mbps

20.5 33.0

21 dBi Dish 50 ft (15.2m)/side

IB ■

_ _ _ 1

11 Mbps

21 dBi Dish 20 ft (6.1m)/side

1

5.5 Mbps

32.6 52.4

21 dBi Dish 50 ft (15.2m)/side

1

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

I

1 1

r——i

1 1

1 1

Note: Distances over 25 miles or 40 Km are very hard to align and install!

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-27

Note: Distances over 25 miles or 40 Km are very hard to align and install!

© 2003, Cisco Systems, Inc. All rights reserved. AWLF v3.1—4-27

At 11 Mbps, using a 21-dBi dish and 50 feet of cable on each side, the 350 Series Bridge will have a range exceeding 20 miles or 33 kilometers. Reducing the loss in the cables by reducing cable length whenever possible or changing to a lower data rate allows this range to extend even further.

Note All distances shown in the illustration are theoretical and may actually be shorter, dependant upon the country of installation, governing bodies, and allowable EIRP levels.

Distances Limited by 802.11 Specification r.y.'.y.^

330000000000000|=[

PCI Card

330000000000000|=[

PCI Card

Point to ANY Client - Maximum Distance

330000000000000 25 IVMI33©)2 iVIbps 40 Km @ 2 Mbps

11.5 Miles @ 11 Mbps 18.5 Km @ 11 Mbps dge to ANY Client - Maximum Distance

© 2003, Cisco Systems, Inc. All rights re

330000000000000 25 IVMI33©)2 iVIbps 40 Km @ 2 Mbps

PCI Card

PCI Card

11.5 Miles @ 11 Mbps 18.5 Km @ 11 Mbps dge to ANY Client - Maximum Distance

© 2003, Cisco Systems, Inc. All rights re

Customers may want to save money and use the workgroup bridge and access point in place of a bridge. If the distance is less than 1 mile and remote end (WGB) has less than 8 end devices, this can be done. However, if the distance is greater than 1 mile, it is recommended that a bridge be used instead of the access point. Using an access point at more than 1 mile will not provide reliable communications. This is due to timing constraints that the 802.11 standard puts on the return times for packets acknowledgements. Remember, 802.11 defines a LAN - Local Area Network - which is typically a wireless range of up to 1000 feet.

The bridge product has a parameter that stretches this timing (which violates 802.11) and allows the Cisco Aironet devices to operate at greater distances. (All bridges that support distances over 1 mile violate 802.11.)

It also means other 802.11 vendors' radios may not work with the Cisco Aironet bridge at distances greater than 1 mile.

Lightning

Cisco.com

Bridge

Ethernet

Static Electricity Wind

Nearby Strikes

S 2OO3, Cisco Systems, Inc. All rights re

The Cisco Lightning Arrestor is designed to protect Cisco Spread Spectrum Wireless LAN devices from static electricity and lightning surges that travel on coaxial transmission lines. The Cisco Aironet lightning arrestor complies with FCC and DOC regulations.

Lightning does not need a direct hit to cause problems. An indirect hit can induce enough energy into the cable and antennas to cause damage to the bridge and other network devices.

Cisco.com To Antenna

Designed to protect LAN devices from static electricity and lightning surges that travel on coax transmission lines

1400 Series (F-connectors)

Nut r

Cisco.com To Antenna

Ground Wire

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