Cisco BR1400, 1400 Series Deployment Manual

1400 Series Wireless Bridge Outdoor Deployment Guide

The purpose for this document is to cover 5 GHz Regulations, 1400 Series Wireless Bridge Product, interference issues, installation guide, troubleshooting tips and added features. This guide will help a Network IT professional, who has limited knowledge about RF, but desires to deploy a wireless Bridge link. This document covers topics that one needs to understand to determine if the wireless link will work, how to design it, how to install it, optimize the link, maintain and troubleshoot it.

1 Introduction to Technology

The BR1400 Bridges are used to wirelessly connect two networks (usually in different buildings). When two or more bridges are used, one bridge must be defined as the ROOT BRIDGE. Cisco wireless bridges default to operation in root bridge mode. In any bridge domain (group of connected bridges) there should exist only one Root Bridge. Other bridges must be configured to operate in non-root mode. The NON-ROOT Bridge will initiate a link to the root bridge and all bridges can subsequently transmit data.

Longer ranges can be activated with appropriate selection of antennas and clear line of sight. It should be noted that only bridges have this extended range capability. The extended range is achieved by stretching the timing parameters set forth in the IEEE 802.11 specifications. The

802.11 specification was based on a presumption that a wireless LAN communication link (keeping in mind this is defining a LOCAL Area Network) would be not more than 1000 feet. Therefore distances for Access Point to client communication are limited to approximately one-mile range for quality performance; irrespective of transmit power, cable, and antenna combinations. This is due to timing restrictions in the 802.11 protocol which synchronize the timing of the communications to support delays induced by the distance.

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Figure 1. Typical Bridge application used to connect different buildings across a

campus or a metro area

Cisco Aironet Bridges support IEEE 802.1d Spanning Tree and can therefore participate in complex Layer 2 network designs involving redundant or meshed links.

1.1 Channels and Data Rates

IEEE 802.11a defines requirements for a PHY operating in the 5.0 GHz Unlicensed National Information Infrastructure (UNII) frequency band and data rates ranging from 6 Mbps to 54 Mbps in seven increments-6, 9, 12, 18, 24, 36, 48 & 54 Mbps. It uses the Orthogonal Frequency Division Multiplexing-, which is a multi carrier system as compared to single carrier systems. OFDM allows sub channels to overlap, giving us a high spectral efficiency. The modulation technique allowed in (OFDM) is more efficient than the spread spectrum techniques use. More bits are stuffed per second per hertz and provides up to 54 Mbps of data rate to network users.

For US-based 802.11a standard, the 5GHz unlicensed band covers 300 MHz of spectrum and supports 12 non-overlapping channels. The channel frequencies and numbering defined in IEEE

802.11a start at 5 GHz for United States and each channel is spaced 5 MHz apart. The Figure 2 below shows the center frequency of the channels. The frequency of the channel is 10MHz either side of the dotted line.

Figure 2. UNII 3 Band

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The 5GHz Band is actually a conglomerate of three Bands in USA: 5.150-5.250(UNII 1), 5.250-

5.350(UNII 2), and 5.725-5.875(UNII 3) GHz. UNII-1 and the UNII-2 bands are contiguous and are indeed treated by 802.11a as being a continuous swath of spectrum 200MHz wide, more than twice the size of the 2.4GHz ISM band. This results in a key benefit for 802.11a—the 200MHz wide UNII-1 and UNII-2 bands are divided up into eight non-overlapping channels, each 25MHz wide.

1.2 Regulations

Outdoor Bridging utilizes UNII 3 band and there are regulatory limitations that apply in this band.

1.2.1 Federal Communications Commission (FCC) Regulations with respect to the UNII 3 Band

Devices that operate in Unlicensed Bands do not require any formal licensing process, but operations in these bands still obligate the user to follow regulations. The geographical bodies in different parts of the world regulate these Bands. WLAN devices must comply with the local geographical regulatory domains. The regulatory agencies set the radio emission requirements for WLAN to minimize the amount of interference a radio can generate or receive from another in the same proximity. The Federal Communications Commission (FCC) is responsible for framing rules and regulations for WLAN operations in a particular band in United States. The set of FCC regulations that apply to WLAN operation in the 5 GHz band is a subset of FCC Part 15 regulations. In addition to US, Australia, New Zealand and various parts of Asia and Oceania also fall in the FCC regulatory domain. For latest information please refer to the following URL:

www.cisco.com/go/aironet/compliance http://www.cisco.com/warp/public/779/smbiz/wireless/approvals.html

1.2.2 Effective Isotropic Radiated Power (EIRP)

The radio energy radiated from an antenna is called the Effective Isotropic Radiated Power (EIRP). The EIRP is usually expressed in Watts or dBm. To enable fair and equitable sharing of the unlicensed band, regulatory domains impose maximum EIRP levels.

Directional antennas, such as Yagi and Parabolic dishes have the capability of shaping the signal from the transmitter so it appears stronger in a particular direction (much the same as the reflector on a flashlight strengthens a light beam). This is known as antenna gain. Antenna cables can add loss attenuating the transmitted signal. The longer the cable, the more attenuation, and the more signal loss in the cable affecting both receive and transmit. Cable attenuation is dependent upon the grade and manufacturer. Low-loss cable is typically around 6.7 dB per 100 ft (30m) at 2.4GHz. As the EIRP is a measure of the power out of the antenna, the EIRP must include the antenna gain and the cable loss together with the power out of the transmitter.

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1.2.3 Power Levels

The UNII-2 band is intended for wireless bridging both for indoor applications as well as short range outdoor applications. UNII-3 band, with far greater transmit power and antenna gain allowances is preferable for long range outdoor wireless bridging.

To facilitate this, the regulations allow for connectors and the use of cable and auxiliary antennas for both of these bands. The effective radiated power allowed in UNII-3 band is 4 watts (36 dBm), which is much more than the radiated power of 1 watt (30 dBm) allowed in UNII-2 band. Rather, the UNII-2 band is treated by the Wi-Fi community as being a less-restrictive extension of the UNII-1 band generally supporting clients and Access Points.

The channel numbers corresponding to the four centre frequencies for UNII-3 band are 149,153, 157 and 161.

Regulatory Domain Frequency Band Channel number Centre frequencies USA UNII middle band

5.725-5.825 GHz

149 153 157 161

5.745 GHz

5.765 GHz

5.785 GHz

5.805 GHz

Table 1. Channel Numbers for UNII-3 Band

The maximum antenna gain allowed is 6dBi. The transmit power may be reduced to accommodate higher gain, more directional antennas while staying within the EIRP limits for a particular band. This is explained in detail, later in this section.

5.15 5.35

5 GHz UNII

Conducted Power

Antenna

Radiated

UNII-1: Indoor Use, antenna must be fixed to the radio

UNII-2: Indoor/Outdoor Use, fixed or remote antenna

UNII-3: Primarily used for Outdoor Bridging

5.25

4Channe

UNII-1 UNII-2 UNII-3

40mW 250mW

(16dBm

6dB

22dB

158mW

4Channe

(24dBm

6dB

30dBm

1 W

5.725

4Channe

36dBm

(30dBm

6dB

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Figure 3. Conducted and Radiated Power Levels in UNII-1,2 & 3 Bands

Wireless systems are certified as complete systems. In the US, the FCC requires that all antennas sold by a Wireless vendor be certified with the radio with which they are to be sold. Cisco Aironet systems are tested and certified for each country using Cisco Aironet components. If amplifiers or third party antennas are used, then it is likely the entire system must be recertified. Systems integrators and installers are responsible for FCC compliance or recertification when using third party equipment.

1.2.4 Other Regulatory Domains

In addition to FCC, other main regulatory domains for operation in 5GHz are European Telecommunications Standards Institute (ETSI), Japan, China (Mainland China), Israel, Singapore and Taiwan (Republic of China). Check the Cisco web site for compliance information and also with your local regulatory authority on what is permitted within your country.

http://www.cisco.com/warp/public/779/smbiz/wireless/approvals.html

ETSI recommended frequency band for bridging is 5.470 to 5.725 GHz offering almost eleven channels with the same EIRP rules as FCC. In exchange of this wide spectrum, the ETSI recommendation mandates the inclusion of two features not currently found in 802.11 products, Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC). DFS and TPC are the two functions handled quite well by the HyperLAN2 specification. The IEEE 802.11h standard covers both DFS and TPC that will apply to the 5 GHz band at a later date.

1.2.5 FCC Regulations regarding EIRP limitations with Point-to-Point & Point-toMultipoint Wireless Networks

Wireless bridges can be deployed to establish a direct link between two sites. The network traffic between the two sites is bridged or forwarded to the other bridge, as if were one network. This is called a point to point link.

Point-to-multipoint wireless links are an expansion of the point-to-point link in which one centralized bridge can establish multiple point-to-point links. Using point-to-multipoint connection, multiple remote sites such as buildings can be linked together into a single logical network. In a point-to-multipoint architecture, these remote sites are linked to a single root bridge at a centralized site.

For point-to-multipoint UNII-3 systems, the directional antenna of 6 dBi gain can be used. And if gain is greater than 6 dBi then the peak transmit power of the device has to be reduced by amount in dB the directional antenna gain exceeds 6 dBi.

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EIRP = Peak Transmit power (30dBm or 1 Watt) + 6 dBi = 36 dB (4 Watts), a constant.

Point-to-point UNII-3 systems, may employ the transmitting antennas of directional gain up to 23 dBi, without any corresponding reduction in peak transmit power. For antennas with gain greater than 23 dBi, a dB reduction in output power is required for every corresponding dB increase in excess of 23 dBi. EIRP = Peak Transmit power (30dBm or 1Watt) + 23 dBi = 53 dB (200 Watts), a constant.

2 BR1400 Wireless Bridge Product Introduction

Cisco’s BR1400 Series, brings about one of the most flexible and feature rich bridging products Cisco has ever made. It was designed to deployed quick and easily in a multitude of different environments and for different purposes.

The BR1400 Series Wireless Bridge is designed for building to building Wireless connectivity. Operating in the 5.8 GHz UNII 3 Band (5725-5825 MHz), derived from the 802.11a standard, the bridge delivers 6 to 54 Mbps data rates without the need for a license.

This allows anyone to deploy FCC certified bridges anywhere in the US without applying for or paying for special licenses (note: some restrictions may apply over special areas such as airports and military bases). This allows for networks to be quickly deployed and then moved if necessary without any licensing or government reporting. An example would be at an airport or Homeland Security application where operations need to place cameras and or other data links near critical areas. By placing a single bridge on top of a tall structure (such as a control tower) and another on a power/light truck pointing toward the control tower, they have effectively made a full secure link. Continuing with the scenario as often as required they could move the power/light truck and effectively move the link through the grounds an endless number of times, each time without worrying about trenching cables or applying for licensees.

Bridge 1400 is IOS based, and it has the following IOS features:

• Transparent bridging between the wired Ethernet and wireless 802.11a Radio Interface.

• Native Ethernet and 802.1q tagging is supported on both the wired Ethernet and wireless

802.11a Radio interfaces.

• Support for 802.1d Spanning Tree Protocol.

• Support for 802.1q Virtual LAN to work in conjunction with a Switch/Router attached to

the BR1400.

• Support for Port Aggregation Protocol (PagP) and Fast Ether Channel (FEC) providing up

to 100 Mbps of combined bandwidth, by stacking two BR1400 bridges.

• QoS support, 8 transmit priority queues are provided in IOS, with 1 queue per

802.1D/802.1p user priority value for the radio interface.

• IP TOS/DSCP based classifications are supported for classifying voice packets.

• Link level redundancy for P2P using STP.

• Security:

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40-bit and 128-bit WEP encryption

802.1x and LEAP AAA Radius Server support Enhanced Encryption Features like TKIP,MIC.

• Voice support for P2P configurations.

• Support for Cisco IP-based protocols like TCP, UDP, TFTP, FTP, ARP, ICMP, CDP,

SNMP, RADIUS, TACACS, SNTP, Telnet and NTP.

• Network management support via three interfaces: SNMP, Web Interface, Telnet/CLI.

• Support for Cisco View network management system.

• IP Address Management, supporting DHCP client/server and DNS client/server

functionality

• Provides diagnostic and statistics information, using any of the management interfaces.

• Installation Mode for aligning the antenna and setting up the ODU at the outdoor site.

2.1 Product Overview

The system consists of a weather proof wireless bridge, a Power Injector- LR, a Power Adaptor, a grounding block at the building entrance and optionally external antennas. The Bridge and the external antennas, if used, are installed outdoors. The grounding Block is installed at the building entrance and the Power Injector LR and DC power supply are installed indoors. The overall System block diagram is shown in the Figure below.

Figure 4. Schematic of Typical Bridge Installation

2.1.1 Wireless Bridge

The BR1400 wireless bridge includes all the RF and Digital Radio circuitry including four external interfaces:

1. A pair of 75 ohm F-type coaxial connectors for Power Injector LR interface functioning as

100 Mbps Ethernet communication port and DC power input.

2. Radio interface, which includes a directional captive antenna or an N-type RF connector

for a remote antenna.

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3. RSSI voltage port for antenna alignment

4. Four LEDs providing system status and antenna alignment feedback.

Due to its rugged design, the BR1400 Series Bridge is designed primarily for outdoor deployments. Unlike other equipment where special care needs to be taken to carefully protect the equipment from the elements such as wind, rain and other weather conditions such as extreme temperature gradients on both ends of the spectrum, the BR1400 series was designed with this exact problem in mind. The BR1400 is plenum rated eliminating the need to have additional NEMA or other weatherproof enclosures and can operate in temperatures ranging from -22°F all the way to 131°F without any external temperature influencing devices. The entire unit is designed to withstand and still operate in severe conditions including very high wind and precipitation of all types.

The BR1400 wireless bridge is available with highly directional captive (built in) antenna. The gain of captive antenna is 22.5 dBi. We also have an option for connecting external antennas under a different SKU where it provides an N-type RF connector for interfacing to various external antennas for greater range and flexibility.

Figure 5. AIR-BR1410A -A-K9 and AIR-BR1410A-A-K9-N

Please note the Radome provides an environmentally sealed enclosure and is not removable from the housing. Therefore, you should plan in advance about what type of network you want to deploy, as these SKUs are not interchangeable in the field. If you wish to use high gain antennas for longer range or perhaps an Omni antenna for multi-point operation you may need to order the SKU on the right of the picture above.

In addition to the conventional role of the radio in the bridge as “Root” or “Non Root”, BR1410 has more roles in radio network which facilitates the installation and alignment. Observable LEDs and the voltage port can be used for alignment, so one does not need a laptop or any other conventional tool for installing these bridges. Please refer to the documentation for BR1410 available on our website:

http://www.cisco.com/en/US/products/hw/wireless/ps5279/index.html

2.1.1.1 Antennas for the BR1400

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The antennas listed here are available as optional remote antennas for the BR1400. The Beamwidth and the gain of the antennas are mentioned in the Tables below.

Part Number Description

AIR-AN58G09VOA-N 5.8 GHz 9 dBi Non-Diversity Omni Vertical Polarization Ant with N-Type Connector

AIR-AN58G10SSA-N 5.8 GHz 10 dBi Non-Diversity Symmetric Sector Antenna with N-Type Connector

AIR-AN58G28SDA-N 5.8 GHz 28 dBi Non-Diversity Symmetric Dish Antenna with N-Type Connector

Table 2. External Antennas for BR1400 Wireless Bridge

Antenna Horizontal Beamwidth (degrees) Vertical Beamwidth (degrees)

Integrated (Captured) 12.0 10.0

Omni 360 6 +/- 0.5

Sector 60.0, minimum 60.0, minimum

Dish 5.7 6.0

Table 3. Beamwidths of the Antennas

Please refer to the installation section in the BR1400 manual for details about which antennas may be used.

2.1.2 Power Injector-LR (Long Reach)

The Power Injector -LR is a self-contained functional unit suitable for indoor installation. It provides a 100 Base-T Ethernet link between the In-building LAN and the outdoor wireless unit (ODU). The main functio n of Power Injector is to provide power onto the Ethernet connection to the ODU. The Ethernet connection to the ODU is via two 75-ohm coax cables, the coaxial cables can be RG6, RG59 or higher quality 75-ohm cable with a maximum length up to 100 meters. The indoor connection to the local LAN uses standard category 5 twisted pair copper and can provide connectivity at lengths up to 100 meters. The Power Injector is powered by the power ada pter and supplies the DC voltage into both coaxial cables powering the ODU.

Please note that these coaxial cables do not carry any RF (radio frequency) energy. All the RF is contained within the Outdoor Unit or Bridge.

The Power Injector has three external interfaces:

1. RJ45 connector for internal 100 baseT LAN interface.

2. A pair of 75 ohm F-type coaxial connectors for 100 baseT interface to the wireless bridge

(ODU).

3. DC power connector interfaced to the power adapter.

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Three LEDs are included on the front power injector as shown in the figure below. They indicate Ethernet activity, Injector Status and Uplink activity. There is a fourth LED (on the side of the box) indicating DC power from the power adapter.

Figure 6. Power Injector-Long Reach

2.1.3 Power Adaptor

Power Adaptor provides +48V DC to the power injector. It is rated to deliver 60 W of DC power. It has two interfaces:

1. DC output through a short cable via a barrel style power connector .25 OD (center

positive) interfacing to Power Injector

2. Universal AC input connector to be plugged into an AC power cord.

2.1.4 Grounding Block

Grounding block (Cisco provided) should be installed inline with 75 ohm coax cables at the building entrance providing lightning protection. It has straight through F-connectors where the shield is connected to the body of the block. This type device is commonly available for CATV type usage by third party vendors.

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2.2 Bridge 1400 Low Power version

There are different SKUs with different power levels for different parts of the world in accordance with the regulatory domains respective to these countries. Refer to the following URL:

www.cisco.com/go/aironet/compliance

We can broadly classify the SKUs as High Power and Low Power versions. The SKU for America and Canada is a High Power version with ability to radiate at maximum output power of 24 dBm. The part numbers for these two SKUs are AIR-BR1410A -A-K9 and AIR-BR1410AA-K9-N as discussed earlier.

In low power version we have three different SKUs as below:

1. AIR-BR1410A-E-K9

• Available Tx Power Settings: 4 & 7 dBm

• Antenna Gain: 22.5 dBi

• Anticipated Countries: Ireland, China, Malaysia, Venezuela

2. AIR-BR1410A-K-K9

• Available Tx Power Settings: 12, 15, 18, 21, & 22 dBm

• Antenna Gain: 20 dBi

• Anticipated Countries: Korea

3. AIR-BR1410A-Z-K9

• Available Tx Power Settings: 4, 7, 8, 9, 10, & 13 dBm

• Antenna Gain: 22.5 dBi

• Anticipated Countries: Australia and New Zealand

All these Low power SKUs operate in the same frequency band as high power SKUs i.e, complete UNII 3 band. Should the installer wish to deploy point-to-multipoint networks using Omni or Sector Antennas in these countries then High power SKU AIR-BR1410A -A-K9-N may be ordered, check with your regulatory agency. High gain dish antenna with 28 dBi is not supported in any of the above countries. The outdoor range calculator can be used to determine distances with these Low power SKUs.

3 Applications

Although we have covered several features of the BR1400 Series, we will now discuss some of the features and functionality used in major Bridging applications.

3.1 VLANs

A VLAN is a group of end stations with a common set of requirements, independent of their physical location. A VLAN has the same attributes as a physical LAN but permits you to group end stations together even if they are not located physically on the same subnet.

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802.1q Virtual LAN support is provided to work in conjunction with the Switch/Router attached to

the 1400 series wireless bridge. Both the wired Ethernet and wireless Radio interface supports VLAN Trunking. Native Ethernet and 802.1q tagging is supported on both the Ethernet and Radio interfaces.

ISL tagging, VTP and DTP are not supported in BR1400. The BR1400 treats VTP message like any other multicast message and Transparently Bridges it across. Thus, the Bridge participates in the 802.1d (spanning-tree) process of bridging two networks together. You extend VLANs into a wireless LAN by adding IEEE 802.11Q tag awareness to the bridge. VLAN 802.1Q trunking is supported between root and non-root bridges through the bridges’ primary SSID. The basic wireless components of a VLAN consist of two or more bridges communicating using wireless technology. The bridge is physically connected through a trunk port to the network VLAN switch on which the VLAN is configured. The physical connection to the VLAN switch is through the bridge’s Ethernet port.

Figure 7. VLANs trunked through the wireless bridge links

In fundamental terms, the key to configuring a bridge to connect to a specific VLAN is by configuring its SSID to recognize that VLAN. Since VLANs are identified by a VLAN ID, it follows that if the SSID on a bridge is configured to recognize a specific VLAN ID, a connection to the VLAN is established. The bridge supports only one infrastructure SSID. You should assign that SSID to the native VLAN. For more information, please consult the VLAN deployment Guide at this URL:

http://www.cisco.com/en/US/products/hw/wireless/ps430/prod_technical_reference09186a00801 444a1.html

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NATIVE VLAN

VLAN 12

Station_A

Station_B

Station_C

Switch_1

VLAN 14

Infrastructure ssid: native VLAN

Figure 8. VLAN CONFIGURATION

VLAN 11

Root

802.1Q Trunk 100Mbps,

VLAN 11

Station_

Non-Root

Switch_2

Station_E

VLAN 12

The main steps to configure the VLANs are:

1) Enable 802.1q trunking on the wired network: On either side of the Link you should console into

the Ethernet port of the Switch to which Bridge is connected and give the following commands:

Interface FastEthernet0/1 Switchport trunk encapsulation dot1q Switchport mode trunk Please note that you must have 100 Mbps Ethernet connections between the switch and the Bridge.

2) Enable 802.1q trunking on the Bridges: Specify the VLAN-id X as the native VLAN on the

root and non root bridges by going into the GUI services and clicking on VLAN.

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Figure 9. Screenshot for VLAN configuration

3) Mapping: Map the native VLAN to the Bridge SSID. For this use the GUI interface and go to

Security and click on SSID Manager. Map the SSID to VLAN X.

Figure 10. Screenshot for VLAN configuration

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4) Add the VLANs: Add the VLANs defined on the switches to the Root and Non Root Bridges.

Like for the above figure, VLANs 11, 12 and 14 have to be added on the Bridges as well, so that these VLANs can be trunked through the wireless link.

3.2 QoS

Implementing QoS in your wireless link makes network performance more predictable and bandwidth utilization more effective. By using QoS feature you can prioritize a specific type of traffic instead of making it a purely FIFO (first in, first out). This is due to the fact that voice/video traffic when subject to delays causes very unfavorable behavior in phone conversations (major lags or even dropped phone calls). This is also true with other types of traffic such as video traffic (which is what we will be testing here in this situation). The following are the objectives of the QoS feature supported in 1400 bridge:

• Provide 802.1p priority bits and 802.1q VLAN tag based QoS

• Provide priority services for VOIP traffic, based upon IP TOS/DSCP

The bridge can only classify traffic based on IP TOS (Type of service bits in IP protocol header) Precedence and DSCP (differentiated services code point) values and put it into the correct priority queues. It has 8 priority queues corresponding to eight 802.11E priority values. The CoS values associated with the eight priority queues are the same as the 802.1d User priority values that are carried in an Ethernet frame, an 802.1q priority tag or an 802.1q VLAN tag. The CoS value is used to select the appropriate 802.11 transmit queue. The bridge uses the radio traffic class definitions to calculate back off times for each packet. As a rule, high-priority packets have short back off times. The default values in the Min and Max Contention Window fields and in the Slot Time fields are based on settings recommended in IEEE Draft Standard 802.11e. We can modify the CwMin and CwMax values depending upon the type of the network and our needs. QoS works even with packet concatenation enabled.

The steps to configure QoS are:

1) First create a QoS policy. Go to services in GUI interface and define a policy.

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Figure 11. Screenshot for QoS configuration

2) Apply the policy: You can apply the policy to the VLAN configured on the bridge. If you

do not use VLANs on your network, you can apply your QoS policies to the bridge’s Ethernet and Radio ports.

Figure 12. Screenshot for QoS configuration

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Cisco BR1400, 1400 Series Deployment Manual

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