Cisco Wireless LAN Controller Configuration Guide, Release 5.0
Chapter 10 - Configuring Radio Resource Management
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Configuring Radio Resource ManagementWireless Device Access

Table Of Contents

Configuring Radio Resource ManagementWireless Device Access

Overview of Radio Resource Management

Radio Resource Monitoring

Dynamic Transmit Power Control

Dynamic Channel Assignment

Coverage Hole Detection and Correction

RRM Benefits

Overview of RF Groups

RF Group Leader

RF Group Name

Configuring an RF Group

Using the GUI to Configure an RF Group

Using the CLI to Configure RF Groups

Viewing RF Group Status

Using the GUI to View RF Group Status

Using the CLI to View RF Group Status

Configuring RRM

Using the GUI to Configure RRM

Using the GUI to Configure RF Group Mode

Using the GUI to Configure Transmit Power Control

Using the GUI to Configure Dynamic Channel Assignment

Using the GUI to Configure Coverage Hole Detection

Using the GUI to Configure RRM Profile Thresholds, Monitoring Channels, and Monitor Intervals

Using the CLI to Configure RRM

Using the CLI to View RRM Settings

Using the CLI to Debug RRM Issues

Overriding RRM

Statically Assigning Channel and Transmit Power Settings to Access Point Radios

Using the GUI to Statically Assign Channel and Transmit Power Settings

Using the CLI to Statically Assign Channel and Transmit Power Settings

Disabling Dynamic Channel and Power Assignment Globally for a Controller

Using the GUI to Disable Dynamic Channel and Power Assignment

Using the CLI to Disable Dynamic Channel and Power Assignment

Enabling Rogue Access Point Detection in RF Groups

Using the GUI to Enable Rogue Access Point Detection in RF Groups

Using the CLI to Enable Rogue Access Point Detection in RF Groups

Configuring CCX Radio Management Features

Radio Measurement Requests

Location Calibration

Using the GUI to Configure CCX Radio Management

Using the CLI to Configure CCX Radio Management

Using the CLI to Obtain CCX Radio Management Information

Using the CLI to Debug CCX Radio Management Issues

Configuring Pico Cell Mode

Guidelines for Using Pico Cell Mode

Using the GUI to Configure Pico Cell Mode

Using the CLI to Configure Pico Cell Mode

Using the CLI to Debug Pico Cell Mode Issues


Configuring Radio Resource ManagementWireless Device Access


This chapter describes radio resource management (RRM) and explains how to configure it on the controllers. It contains these sections:

Overview of Radio Resource Management

Overview of RF Groups

Configuring an RF Group

Viewing RF Group Status

Configuring RRM

Overriding RRM

Enabling Rogue Access Point Detection in RF Groups

Configuring CCX Radio Management Features

Configuring Pico Cell Mode

Overview of Radio Resource Management

The radio resource management (RRM) software embedded in the controller acts as a built-in RF engineer to consistently provide real-time RF management of your wireless network. RRM enables controllers to continually monitor their associated lightweight access points for the following information:

Traffic load—The total bandwidth used for transmitting and receiving traffic. It enables wireless LAN managers to track and plan network growth ahead of client demand.

Interference—The amount of traffic coming from other 802.11 sources.

Noise—The amount of non-802.11 traffic that is interfering with the currently assigned channel.

Coverage—The received signal strength (RSSI) and signal-to-noise ratio (SNR) for all connected clients.

Other —The number of nearby access points.

Using this information, RRM can periodically reconfigure the 802.11 RF network for best efficiency. To do this, RRM performs these functions:

Radio resource monitoring

Dynamic transmit power control

Dynamic channel assignment

Coverage hole detection and correction

Radio Resource Monitoring

RRM automatically detects and configures new controllers and lightweight access points as they are added to the network. It then automatically adjusts associated and nearby lightweight access points to optimize coverage and capacity.

Lightweight access points can simultaneously scan all valid 802.11a/b/g channels for the country of operation as well as for channels available in other locations. The access point goes "off-channel" for a period not greater than 60 ms to monitor these channels for noise and interference. Packets collected during this time are analyzed to detect rogue access points, rogue clients, ad-hoc clients, and interfering access points.


Note If packets have been in the voice queue in the last 100 ms, the access point does not go off-channel.


By default, each access point spends only 0.2 percent of its time off-channel. This activity is distributed across all access points so that adjacent access points are not scanning at the same time, which could adversely affect wireless LAN performance. In this way, administrators gain the perspective of every access point, thereby increasing network visibility.

Dynamic Transmit Power Control

The controller dynamically controls access point transmit power based on real-time wireless LAN conditions. Normally, power can be kept low to gain extra capacity and reduce interference. The controller attempts to balance access points such that they see their fourth strongest neighbor at an optimal -65 dbm or better.

The transmit power control algorithm only reduces an access point's power. However, the coverage hole algorithm, explained below, can increase access point power, thereby filling a coverage hole. For example, if a failed access point is detected, the coverage hole algorithm can automatically increase power on surrounding access points to fill the gap created by the loss in coverage.


Note See Step 4 on page 10-26 for an explanation of the transmit power levels.


Dynamic Channel Assignment

Two adjacent access points on the same channel can cause either signal contention or signal collision. In the case of a collision, data is simply not received by the access point. This functionality can become a problem, for example, when someone reading e-mail in a café affects the performance of the access point in a neighboring business. Even though these are completely separate networks, someone sending traffic to the café on channel 1 can disrupt communication in an enterprise using the same channel. Controllers address this problem by dynamically allocating access point channel assignments to avoid conflict and to increase capacity and performance. Channels are "reused" to avoid wasting scarce RF resources. In other words, channel 1 is allocated to a different access point far from the café, which is more effective than not using channel 1 altogether.

The controller's dynamic channel assignment capabilities are also useful in minimizing adjacent channel interference between access points. For example, two overlapping channels in the 802.11b/g band, such as 1 and 2, cannot both simultaneously use 11/54 Mbps. By effectively reassigning channels, the controller keeps adjacent channels separated, thereby avoiding this problem.

The controller examines a variety of real-time RF characteristics to efficiently handle channel assignments. These include:

Access point received energy—The received signal strength measured between each access point and its nearby neighboring access points. Channels are optimized for the highest network capacity.

Noise—Noise can limit signal quality at the client and access point. An increase in noise reduces the effective cell size and degrades user experience. By optimizing channels to avoid noise sources, the controller can optimize coverage while maintaining system capacity. If a channel is unusable due to excessive noise, that channel can be avoided.

802.11 Interference—Interference is any 802.11 traffic that is not part of your wireless LAN, including rogue access points and neighboring wireless networks. Lightweight access points constantly scan all channels looking for sources of interference. If the amount of 802.11 interference exceeds a predefined configurable threshold (the default is 10 percent), the access point sends an alert to the controller. Using the RRM algorithms, the controller may then dynamically rearrange channel assignments to increase system performance in the presence of the interference. Such an adjustment could result in adjacent lightweight access points being on the same channel, but this setup is preferable to having the access points remain on a channel that is unusable due to an interfering foreign access point.

In addition, if other wireless networks are present, the controller shifts the usage of channels to complement the other networks. For example, if one network is on channel 6, an adjacent wireless LAN is assigned to channel 1 or 11. This arrangement increases the capacity of the network by limiting the sharing of frequencies. If a channel has virtually no capacity remaining, the controller may choose to avoid this channel. In very dense deployments in which all non-overlapping channels are occupied, the controller does its best, but you must consider RF density when setting expectations.

Utilization—When utilization monitoring is enabled, capacity calculations can consider that some access points are deployed in ways that carry more traffic than other access points (for example, a lobby versus an engineering area). The controller can then assign channels to improve the access point with the worst performance (and therefore utilization) reported.

Load—Load is taken into account when changing the channel structure to minimize the impact on clients currently in the wireless LAN. This metric keeps track of every access point's transmitted and received packet counts to determine how busy the access points are. New clients avoid an overloaded access point and associate to a new access point.

The controller combines this RF characteristic information with RRM algorithms to make system-wide decisions. Conflicting demands are resolved using soft-decision metrics that guarantee the best choice for minimizing network interference. The end result is optimal channel configuration in a three-dimensional space, where access points on the floor above and below play a major factor in an overall wireless LAN configuration.

Coverage Hole Detection and Correction

The RRM coverage hole detection algorithm is designed to detect areas of radio coverage in a wireless LAN that are below the level needed for robust radio performance. This feature can alert you to the need for an additional (or relocated) lightweight access point.

If clients on a lightweight access point are detected at received signal strength indication (RSSI) levels that are lower than the thresholds specified in the RRM configuration, the access point sends a "coverage hole" alert to the controller. The alert indicates the existence of an area where clients are continually experiencing poor signal coverage, without having a viable access point to which to roam. The controller discriminates between coverage holes that can and cannot be corrected. For coverage holes that can be corrected, the controller mitigates the coverage hole by increasing the transmit power level for that specific access point. The controller does not mitigate coverage holes caused by clients that are unable to increase their transmit power or are statically set to a power level because increasing their downstream transmit power is not a remedy for poor upstream performance and might increase interference in the network.


Note Administrators can use the Cisco Wireless Control System (WCS) to view the location of coverage holes. Refer to the Cisco Wireless Control System Configuration Guide for instructions.


RRM Benefits

RRM produces a network with optimal capacity, performance, and reliability while enabling you to avoid the cost of laborious historical data interpretation and individual lightweight access point reconfiguration. It also frees you from having to continually monitor the network for noise and interference problems, which can be transient and difficult to troubleshoot. Finally, RRM ensures that clients enjoy a seamless, trouble-free connection throughout the Cisco unified wireless network.

RRM uses separate monitoring and control for each deployed network: 802.11a and 802.11b/g. That is, the RRM algorithms run separately for each radio type (802.11a and 802.11b/g). RRM uses both measurements and algorithms. RRM measurements can be adjusted using monitor intervals, but they cannot be disabled. RRM algorithms, on the other hand, are enabled automatically but can be disabled by statically configuring channel and power assignment. The RRM algorithms run at a specified updated interval, which is 600 seconds by default.


Note RRM measurements are postponed on a per access point basis where traffic remains in the platinum QoS queue, if there was voice traffic in the last 100 ms.


Overview of RF Groups

An RF group, also known as an RF domain, is a cluster of controllers that coordinates its RRM calculations on a per 802.11-network basis. An RF group exists for each 802.11 network type. Clustering controllers into RF groups enables the RRM algorithms to scale beyond a single controller.

Lightweight access points periodically send out neighbor messages over the air. The RRM algorithms use a shared secret that is configured on the controller and sent to each access point. Access points sharing the same secret are able to validate messages from each other. When access points on different controllers hear validated neighbor messages at a signal strength of -80 dBm or stronger, the controllers dynamically form an RF group.


Note RF groups and mobility groups are similar in that they both define clusters of controllers, but they are different in terms of their use. These two concepts are often confused because the mobility group name and RF group name are configured to be the same in the Startup Wizard. Most of the time, all of the controllers in an RF group are also in the same mobility group and vice versa. However, an RF group facilitates scalable, system-wide dynamic RF management while a mobility group facilitates scalable, system-wide mobility and controller redundancy. Refer to Chapter 11 for more information on mobility groups.


Controller software release 4.2.99.0 or later supports up to 20 controllers and 1000 access points in an RF group. For example, a Cisco WiSM controller supports up to 150 access points, so you can have up to 6 WiSM controllers in an RF group (150 access points x 6 controllers = 900 access points, which is less than 1000). Similarly, a 4404 controller supports up to 100 access points, so you can have up to 10 4404 controllers in an RF group (100 x 10 = 1000). The 2100-series-based controllers support a maximum of 25 access points, so you can have up to 20 of these controllers in an RF group.


Note In controller software release 4.2.61.0 or earlier, RRM supports no more than five 4400-series-based controllers in an RF group.


RF Group Leader

The members of an RF group elect an RF group leader to maintain a "master" power and channel scheme for the group. The RF group leader is dynamically chosen and cannot be selected by the user. In addition, the RF group leader can change at any time, depending on the RRM algorithm calculations.

The RF group leader analyzes real-time radio data collected by the system and calculates the master power and channel plan. The RRM algorithms try to optimize around a signal strength of -65 dBm between all access points and to avoid 802.11 co-channel interference and contention as well as non-802.11 interference. The RRM algorithms employ dampening calculations to minimize system-wide dynamic changes. The end result is dynamically calculated optimal power and channel planning that is responsive to an always changing RF environment.

The RRM algorithms run at a specified updated interval, which is 600 seconds by default. Between update intervals, the RF group leader sends keep-alive messages to each of the RF group members and collects real-time RF data.


Note Several monitoring intervals are also available. See the "Configuring RRM" section for details.


RF Group Name

A controller is configured with an RF group name, which is sent to all access points joined to the controller and used by the access points as the shared secret for generating the hashed MIC in the neighbor messages. To create an RF group, you simply configure all of the controllers to be included in the group with the same RF group name.

If there is any possibility that an access point joined to a controller may hear RF transmissions from an access point on a different controller, the controllers should be configured with the same RF group name. If RF transmissions between access points can be heard, then system-wide RRM is recommended to avoid 802.11 interference and contention as much as possible.

Configuring an RF Group

This section provides instructions for configuring RF groups through either the GUI or the CLI.


Note The RF group name is generally set at deployment time through the Startup Wizard. However, you can change it as necessary.



Note When the multiple-country feature is being used, all controllers intended to join the same RF group must be configured with the same set of countries, configured in the same order.



Note You can also configure RF groups using the Cisco Wireless Control System (WCS). Refer to the Cisco Wireless Control System Configuration Guide for instructions.


Using the GUI to Configure an RF Group

Follow these steps to create an RF group using the GUI.


Step 1 Click Controller > General to open the General page (see Figure 10-1).

Figure 10-1 General Page

Step 2 Enter a name for the RF group in the RF-Network Name field. The name can contain up to 19 ASCII characters.

Step 3 Click Apply to commit your changes.

Step 4 Click Save Configuration to save your changes.

Step 5 Repeat this procedure for each controller that you want to include in the RF group.


Using the CLI to Configure RF Groups

Follow these steps to configure an RF group using the CLI.


Step 1 Enter config network rf-network-name name to create an RF group.


Note Enter up to 19 ASCII characters for the group name.


Step 2 Enter show network to view the RF group.

Step 3 Enter save config to save your settings.

Step 4 Repeat this procedure for each controller that you want to include in the RF group.


Viewing RF Group Status

This section provides instructions for viewing the status of the RF group through either the GUI or the CLI.


Note You can also view the status of RF groups using the Cisco Wireless Control System (WCS). Refer to the Cisco Wireless Control System Configuration Guide for instructions.


Using the GUI to View RF Group Status

Follow these steps to view the status of the RF group using the GUI.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > RF Grouping to open the 802.11a (or 802.11b/g) RRM > RF Grouping page (see Figure 10-2).

Figure 10-2 802.11a > RRM > RF Grouping Page

This page shows the details of the RF group, specifically how often the group information is updated (600 seconds by default), the MAC address of the RF group leader, whether this particular controller is the group leader, the last time the group information was updated, and the MAC addresses of all group members.


Note Automatic RF grouping, which is set through the Group Mode check box, is enabled by default. See the "Using the GUI to Configure RF Group Mode" section for more information on this parameter.


Step 2 If desired, repeat this procedure for the network type you did not select (802.11a or 802.11b/g).


Using the CLI to View RF Group Status

Follow these steps to view the status of the RF group using the CLI.


Step 1 Enter show advanced 802.11a group to see which controller is the RF group leader for the 802.11a RF network. Information similar to the following appears:

Radio RF Grouping
  802.11a Group Mode............................. AUTO
  802.11a Group Update Interval.................. 600 seconds
  802.11a Group Leader........................... 00:16:9d:ca:d9:60
 	802.11a Group Member......................... 00:16:9d:ca:d9:60
  802.11a Last Run............................ 594 seconds ago 

This text shows the details of the RF group, specifically whether automatic RF grouping is enabled for this controller, how often the group information is updated (600 seconds by default), the MAC address of the RF group leader, the MAC address of this particular controller, and the last time the group information was updated.


Note If the MAC addresses of the group leader and the group member are identical, this controller is currently the group leader.


Step 2 Enter show advanced 802.11b group to see which controller is the RF group leader for the 802.11b/g RF network.


Configuring RRM

The controller's preconfigured RRM settings are optimized for most deployments. However, you can modify the controller's RRM configuration parameters at any time through either the GUI or the CLI.


Note You can configure these parameters on controllers that are part of an RF group or on controllers that are not part of an RF group.



Note The RRM parameters should be set to the same values on every controller in an RF group. The RF group leader can change at any time. If the RRM parameters are not identical for all RF group members, varying results can occur when the group leader changes.


Using the GUI to Configure RRM

Using the controller GUI, you can configure the following RRM parameters: RF group mode, transmit power control, dynamic channel assignment, coverage hole detection, profile thresholds, monitoring channels, and monitor intervals. To configure these parameters, follow the instructions in the subsections below.

Using the GUI to Configure RF Group Mode

Using the controller GUI, follow these steps to configure RF group mode.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > RF Grouping to open the 802.11a (or 802.11b/g) RRM > RF Grouping page (see Figure 10-2).

Step 2 Check the Group Mode check box to enable this controller to participate in an RF group, or uncheck it to disable this feature. If you enable this feature, the controller automatically forms an RF group with other controllers, and the group dynamically elects a leader to optimize RMM parameter settings for the the group. If you disable it, the controller does not participate in automatic RF grouping; instead it optimizes the access points connected directly to it. The default value is checked.


Note Cisco recommends that controllers participate in automatic RF grouping. Note that you can override RRM settings without disabling automatic RF group participation. See the "Overriding RRM" section for instructions.


Step 3 Click Apply to commit your changes.

Step 4 Click Save Configuration to save your changes.


Using the GUI to Configure Transmit Power Control

Using the controller GUI, follow these steps to configure dynamic transmit power control settings.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > TPC to open the 802.11a (or 802.11b/g) > RRM > Tx Power Control (TPC) page (see Figure 10-3).

Figure 10-3 802.11a > RRM > Tx Power Control (TPC) Page

Step 2 Choose one of the following options from the Power Level Assignment Method drop-down box to specify the controller's dynamic power assignment mode:

Automatic—Causes the controller to periodically evaluate and, if necessary, update the transmit power for all joined access points. This is the default value.

On Demand—Causes the controller to periodically evaluate the transmit power for all joined access points. However, the controller updates the power, if necessary, only when you click Invoke Power Update Now.


Note The controller does not evaluate and update the transmit power immediately after you click Invoke Power Update Now. It waits for the next 600-second interval. This value is not configurable.


Fixed—Prevents the controller from evaluating and, if necessary, updating the transmit power for joined access points. The power level is set to the fixed value chosen from the drop-down box.


Note The transmit power level is assigned an integer value instead of a value in mW or dBm. The integer corresponds to a power level that varies depending on the regulatory domain in which the access points are deployed. See Step 4 on page 10-26 for information on available transmit power levels.



Note For optimal performance, Cisco recommends that you use the Automatic setting. Refer to the "Disabling Dynamic Channel and Power Assignment Globally for a Controller" section for instructions if you ever need to disable the controller's dynamic channel and power settings.


This page also shows the following non-configurable transmit power level parameter settings:

Power Threshold—The cutoff signal level used by RRM when determining whether to reduce an access point's power. The default value for this parameter is -65 dBm but can be changed through the controller CLI on rare occasions when access points are transmitting at higher (or lower) than desired power levels. See the "Using the CLI to Configure RRM" section for the CLI command.

Power Neighbor Count—The minimum number of neighbors an access point must have for the transmit power control algorithm to run.

Power Assignment Leader—The MAC address of the RF group leader, which is responsible for power level assignment.

Last TPC Iteration—The last time RRM evaluated the current transmit power level assignments.

Step 3 Click Apply to commit your changes.

Step 4 Click Save Configuration to save your changes.


Using the GUI to Configure Dynamic Channel Assignment

Using the controller GUI, follow these steps to specify the channels that the dynamic channel assignment (DCA) algorithm considers when selecting the channels to be used for RRM scanning. This functionality is helpful when you know that the clients do not support certain channels because they are legacy devices or they have certain regulatory restrictions.


Note If a WLAN is configured to an 802.11g only radio policy and a LAP is configured to channel 14, then the WLAN clients try to associate with the LAP, which does not work as expected because of the 802.11g only policy. The workaround to the problem is one of the following:
- Disable channel 14 manually when 802.11g only policy is configured in WLANs.
- Do not select 802.11g only policy when channel 14 is configured to a LAP.



Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > DCA to open the 802.11a (or 802.11b/g) > RRM > Dynamic Channel Assignment (DCA) page (see Figure 10-4).

Figure 10-4 802.11a > RRM > Dynamic Channel Assignment (DCA) Page

Step 2 Choose one of the following options from the Channel Assignment Method drop-down box to specify the controller's DCA mode:

Automatic—Causes the controller to periodically evaluate and, if necessary, update the channel assignment for all joined access points. This is the default value.

On Demand—Causes the controller to periodically evaluate the channel assignment for all joined access points. However, the controller reassigns channels, if necessary, only when you click Invoke Channel Update Now.


Note The controller does not evaluate and update the channel immediately after you click Invoke Channel Update Now. It waits for the next interval to elapse.


OFF—Prevents the controller from evaluating and, if necessary, updating the channel assignment for joined access points.


Note For optimal performance, Cisco recommends that you use the Automatic setting. Refer to the "Disabling Dynamic Channel and Power Assignment Globally for a Controller" section for instructions if you ever need to disable the controller's dynamic channel and power settings.


The Interval field shows how often the DCA algorithm has been configured to run. The default value is 600 seconds. The Anchor Time field shows the time of day when the DCA algorithm has been configured to start. The range is 12:00 a.m. to 11:00 p.m.


Note You can configure the interval and anchor time using the controller CLI. See the "Using the CLI to Configure RRM" section for details.


Step 3 Check the Avoid Foreign AP Interference check box to cause the controller's RRM algorithms to consider 802.11 traffic from foreign access points (those not included in your wireless network) when assigning channels to lightweight access points, or uncheck it to disable this feature. For example, RRM may adjust the channel assignment to have access points avoid channels close to foreign access points. The default value is checked.

Step 4 Check the Avoid Cisco AP Load check box to cause the controller's RRM algorithms to consider 802.11 traffic from Cisco lightweight access points in your wireless network when assigning channels, or uncheck it to disable this feature. For example, RRM can assign better reuse patterns to access points that carry a heavier traffic load. The default value is unchecked.

Step 5 Check the Avoid Non-802.11a (802.11b) Noise check box to cause the controller's RRM algorithms to consider noise (non-802.11 traffic) in the channel when assigning channels to lightweight access points, or uncheck it to disable this feature. For example, RRM may have access points avoid channels with significant interference from non-access point sources, such as microwave ovens. The default value is checked.

This page also shows the following non-configurable channel parameter settings:

Channel Assignment Leader—The MAC address of the RF group leader, which is responsible for channel assignment.

Last DCA Iteration—The last time RRM evaluated the current channel assignments.

DCA Sensitivity Level—The configured DCA sensitivity setting: low, medium, or high. This setting determines how sensitive the DCA algorithm is to environmental changes such as signal, load, noise, and interference when determining whether to change channels.


Note You can use the config advanced {802.11a | 802.11b} channel dca sensitivity {low | medium | high} CLI command to configure the DCA sensitivity level. See the "Using the CLI to Configure RRM" section for details.


Step 6 In the DCA Channel List section, the DCA Channels field shows the channels that are currently selected. To select a channel, check its check box in the Select column. To exclude a channel, uncheck its check box.

Range:
802.11a—36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 132, 136, 140, 149, 153, 157, 161, 165, 190, 196
802.11b/g—1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Default:
802.11a—36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 132, 136, 140, 149, 153, 157, 161
802.11b/g—1, 6, 11

Step 7 Click Apply to commit your changes.

Step 8 Click Save Configuration to save your changes.


Note To see why the DCA algorithm changed channels, click Monitor and then View All under Most Recent Traps. The trap provides the MAC address of the radio that changed channels, the previous channel and the new channel, the reason why the change occurred, the energy before and after the change, the noise before and after the change, and the interference before and after the change.



Using the GUI to Configure Coverage Hole Detection

Using the controller GUI, follow these steps to enable coverage hole detection.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > Coverage to open the 802.11a (or 802.11b/g) > RRM > Coverage page (see Figure 10-5).

Figure 10-5 802.11a > RRM > Coverage Page

Step 2 Check the Enable Coverage Hole Detection check box to enable coverage hole detection, or uncheck it to disable this feature. If you enable coverage hole detection, the controller automatically determines, based on data received from the access points, if any access points have clients that are potentially located in areas with poor coverage. The default value is checked.

Step 3 In the Data RSSI field, enter the minimum receive signal strength indication (RSSI) value for data packets received by the access point. The value that you enter is used to identify coverage holes (or areas of poor coverage) within your network. If the access point receives a packet in the data queue with an RSSI value below the value that you enter here, a potential coverage hole has been detected. The valid range is -60 to -90 dBm, and the default value is -80 dBm. The access point takes data RSSI measurements every 5 seconds and reports them to the controller in 90-second intervals.

Step 4 In the Voice RSSI field, enter the minimum receive signal strength indication (RSSI) value for voice packets received by the access point. The value that you enter is used to identify coverage holes within your network. If the access point receives a packet in the voice queue with an RSSI value below the value that you enter here, a potential coverage hole has been detected. The valid range is -60 to -90 dBm, and the default value is -75 dBm. The access point takes voice RSSI measurements every 5 seconds and reports them to the controller in 90-second intervals.

Step 5 In the Min Failed Client Count per AP field, enter the minimum number of clients on an access point with an RSSI value at or below the data or voice RSSI threshold. The valid range is 1 to 75, and the default value is 3.

Step 6 In the Coverage Exception Level per AP field, enter the percentage of clients on an access point that are experiencing a low signal level but cannot roam to another access point. The valid range is 0 to 100%, and the default value is 25%.


Note If both the number and percentage of failed packets exceed the values configured for Failed Packet Count and Failed Packet Percentage (configurable through the controller CLI; see page 20) for a 5-second period, the client is considered to be in a pre-alarm condition. The controller uses this information to distinguish between real and false coverage holes. False positives are generally due to the poor roaming logic implemented on most clients. A coverage hole is detected if both the number and percentage of failed clients meet or exceed the values entered in the Min Failed Client Count per AP and Coverage Exception Level per AP fields over a 90-second period. The controller determines if the coverage hole can be corrected and, if appropriate, mitigates the coverage hole by increasing the transmit power level for that specific access point.


Step 7 Click Apply to commit your changes.

Step 8 Click Save Configuration to save your changes.


Using the GUI to Configure RRM Profile Thresholds, Monitoring Channels, and Monitor Intervals

Using the controller GUI, follow these steps to configure RRM profile thresholds, monitoring channels, and monitor intervals.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > General to open the 802.11a (or 802.11b/g) > RRM > General page (see Figure 10-6).

Figure 10-6 802.11a > RRM > General Page

Step 2 To configure profile thresholds used for alarming, follow these steps.


Note The profile thresholds have no bearing on the functionality of the RRM algorithms. Lightweight access points send an SNMP trap (or an alert) to the controller when the values set for these threshold parameters are exceeded.


a. In the Interference field, enter the percentage of interference (802.11 traffic from sources outside of your wireless network) on a single access point. The valid range is 0 to 100%, and the default value is 10%.

b. In the Clients field, enter the number of clients on a single access point. The valid range is 1 to 75, and the default value is 12.

c. In the Noise field, enter the level of noise (non-802.11 traffic) on a single access point. The valid range is -127 to 0 dBm, and the default value is -70 dBm.

d. In the Utilization field, enter the percentage of RF bandwidth being used by a single access point. The valid range is 0 to 100%, and the default value is 80%.

Step 3 From the Channel List drop-down box, choose one of the following options to specify the set of channels that the access point uses for RRM scanning:

All Channels—RRM channel scanning occurs on all channels supported by the selected radio, which includes channels not allowed in the country of operation.

Country Channels—RRM channel scanning occurs only on the data channels in the country of operation. This is the default value.

DCA Channels—RRM channel scanning occurs only on the channel set used by the DCA algorithm, which by default includes all of the non-overlapping channels allowed in the country of operation. However, you can specify the channel set to be used by DCA if desired. To do so, follow the instructions in the "Using the GUI to Configure Dynamic Channel Assignment" section.

Step 4 To configure monitor intervals, follow these steps:

a. In the Noise Measurement field, enter (in seconds) how frequently the access point measures noise and interference. The valid range is 60 to 3600 seconds, and the default value is 180 seconds.

b. In the Load Measurement field, enter (in seconds) how frequently the access point collects information about the channel load, which is then incorporated into the DCA algorithm. The valid range is 60 to 3600 seconds, and the default value is 60 seconds.

c. In the Neighbor Packet Frequency field, enter (in seconds) how frequently the access point measures signal strength and how frequently neighbor packets (messages) are sent, which eventually builds the neighbor list. The valid range is 60 to 3600 seconds, and the default value is 60 seconds.


Note In controller software release 4.1.185.0 or later, if the access point radio does not receive a neighbor packet from an existing neighbor within 60 minutes, the controller deletes that neighbor from the neighbor list. In controller software releases prior to 4.1.185.0, the controller waits only 20 minutes before deleting an unresponsive neighbor radio from the neighbor list.


d. In the Channel Scan Duration field, enter (in seconds) the sum of the time between scans for each channel within a radio band. The entire scanning process takes 50 ms per channel, per radio and runs at the Channel Scan Duration interval. The time spent listening on each channel is determined by the non-configurable 50-ms scan time and the number of channels to be scanned. For example, in the U.S. all 11 802.11b/g channels are scanned for 50 ms each within the default 180-second interval. So every 16 seconds, 50 ms is spent listening on each scanned channel (180/11 = ~16 seconds). The amount of time allocated for the entire scanning process. The Channel Scan Duration parameter determines the interval at which the scanning occurs.The valid range is 60 to 3600 seconds, and the default value is 60 seconds for 802.11a radios and 180 seconds for the 802.11b/g radios.

Step 5 Click Apply to commit your changes.

Step 6 Click Save Configuration to save your changes.


Note Click Set to Factory Default if you ever want to return all of the controller's RRM parameters to their factory default values.



Using the CLI to Configure RRM

Using the controller CLI, follow these steps to configure RRM.


Step 1 Enter this command to disable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} disable

Step 2 Perform one of the following to configure transmit power control:

To have RRM automatically set the transmit power for all 802.11a or 802.11b/g radios at periodic intervals, enter this command:

config {802.11a | 802.11b} txPower global auto

To have RRM automatically reset the transmit power for all 802.11a or 802.11b/g radios one time, enter this command:

config {802.11a | 802.11b} txPower global once

To manually change the default transmit power setting of -65 dBm, enter this command:

config advanced {802.11a | 802.11b} tx-power-control-thresh threshold

where threshold is a value from -50 to -80 dBm. Increasing this value (between -50 and -65 dBm) causes the access points to operate at higher transmit power rates. Decreasing the value has the opposite effect.

In applications with a dense population of access points, it may be useful to decrease the threshold to -75 or -80 dBm in order to reduce the number of BSSIDs (access points) and beacons seen by the wireless clients. Some wireless clients may have difficulty processing a large number of BSSIDs or a high beacon rate and may exhibit problematic behavior with the default threshold.


Note See the Power Threshold description in "Using the GUI to Configure Transmit Power Control" section for more information.


Step 3 Perform one of the following to configure dynamic channel assignment (DCA):

To have RRM automatically configure all 802.11a or 802.11b/g channels based on availability and interference, enter this command:

config {802.11a | 802.11b} channel global auto

To have RRM automatically reconfigure all 802.11a or 802.11b/g channels one time based on availability and interference, enter this command:

config {802.11a | 802.11b} channel global once

To disable RRM and set all channels to their default values, enter this command:

config {802.11a | 802.11b} channel global off

To specify the channel set used for DCA, enter this command:

config advanced {802.11a | 802.11b} channel {add | delete} channel_number

You can enter only one channel number per command. This command is helpful when you know that the clients do not support certain channels because they are legacy devices or they have certain regulatory restrictions.

Step 4 Use these commands to configure additional DCA parameters:

config advanced {802.11a | 802.11b} channel dca anchor-time value—Specifies the time of day when the DCA algorithm is to start. Value is a number between 0 and 23 (inclusive) representing the hour of the day from 12:00 a.m. to 11:00 p.m.

config advanced {802.11a | 802.11b} channel dca interval value—Specifies how often the DCA algorithm is allowed to run. Value is one of the following: 1, 2, 3, 4, 6, 8, 12, or 24 hours or 0, which is the default value of 10 minutes (or 600 seconds).

config advanced {802.11a | 802.11b} channel dca sensitivity {low | medium | high}—Specifies how sensitive the DCA algorithm is to environmental changes such as signal, load, noise, and interference when determining whether to change channel.

low means that the DCA algorithm is not particularly sensitive to environmental changes.

medium means that the DCA algorithm is moderately sensitive to environmental changes.

high means that the DCA algorithm is highly sensitive to environmental changes.

The DCA sensitivity thresholds vary by radio band, as noted in

Table 10-1 DCA Sensitivity Thresholds

 
2.4-GHz DCA Sensitivity Threshold
5-GHz DCA Sensitivity Threshold
High

5 dB

5 dB

Medium

15 dB

20 dB

Low

30 dB

35 dB


Table 10-1.

config advanced {802.11a | 802.11b} channel foreign {enable | disable}—Enables or disables foreign access point interference avoidance in the channel assignment.

config advanced {802.11a | 802.11b} channel load {enable | disable}—Enables or disables load avoidance in the channel assignment.

config advanced {802.11a | 802.11b} channel noise {enable | disable}—Enables or disables noise avoidance in the channel assignment.

config advanced {802.11a | 802.11b} channel update—Initiates an update of the channel selection for every Cisco access point.

Step 5 Use these commands to configure coverage hole detection:

config advanced {802.11a | 802.11b} coverage {enable | disable}—Enables or disables coverage hole detection. If you enable coverage hole detection, the controller automatically determines, based on data received from the access points, if any access points have clients that are potentially located in areas with poor coverage. The default value is enabled.

config advanced {802.11a | 802.11b} coverage {data | voice} rssi-threshold rssi—Specifies the minimum receive signal strength indication (RSSI) value for packets received by the access point. The value that you enter is used to identify coverage holes (or areas of poor coverage) within your network. If the access point receives a packet in the data or voice queue with an RSSI value below the value you enter here, a potential coverage hole has been detected. The valid range is -60 to -90 dBm, and the default value is -80 dBm for data packets and -75 dBm for voice packets. The access point takes RSSI measurements every 5 seconds and reports them to the controller in 90-second intervals.

config advanced {802.11a | 802.11b} coverage level global clients—Specifies the minimum number of clients on an access point with an RSSI value at or below the data or voice RSSI threshold. The valid range is 1 to 75, and the default value is 3.

config advanced {802.11a | 802.11b} coverage exception global percent—Specifies the percentage of clients on an access point that are experiencing a low signal level but cannot roam to another access point. The valid range is 0 to 100%, and the default value is 25%.

config advanced {802.11a | 802.11b} coverage {data | voice} packet-count packets—Specifies the minimum failure count threshold for uplink data or voice packets. The valid range is 1 to 255 packets, and the default value is 10 packets.

config advanced {802.11a | 802.11b} coverage {data | voice} fail-rate percent—Specifies the failure rate threshold for uplink data or voice packets. The valid range is 1 to 100%, and the default value is 20%.


Note If both the number and percentage of failed packets exceed the values entered in the packet-count and fail-rate commands for a 5-second period, the client is considered to be in a pre-alarm condition. The controller uses this information to distinguish between real and false coverage holes. False positives are generally due to the poor roaming logic implemented on most clients. A coverage hole is detected if both the number and percentage of failed clients meet or exceed the values entered in the coverage level global and coverage exception global commands over a 90-second period. The controller determines if the coverage hole can be corrected and, if appropriate, mitigates the coverage hole by increasing the transmit power level for that specific access point.


Step 6 Enter this command to enable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} enable


Note To enable the 802.11g network, enter config 802.11b 11gSupport enable after the config 802.11b enable command.


Step 7 Enter this command to save your settings:

save config


Using the CLI to View RRM Settings

Use this command to view additional 802.11a and 802.11b/g RRM settings:

show advanced {802.11a | 802.11b} ?

where ? is one of the following:

ccx {global | Cisco_AP}—Shows the CCX RRM configuration.

802.11a Client Beacon Measurements:
    disabled 

channel—Shows the channel assignment configuration and statistics.

Automatic Channel Assignment
  Channel Assignment Mode........................ AUTO
  Channel Update Interval........................ 600 seconds
  Anchor time (Hour of the day).................. 0
  Channel Update Contribution.................... SNI.
  Channel Assignment Leader...................... 00:0b:85:43:dd:c0
  Last Run....................................... 426 seconds ago

  DCA Sensitivity Level: ...................... MEDIUM (20 dB)
  Channel Energy Levels
    Minimum...................................... unknown
    Average...................................... unknown
    Maximum...................................... unknown
  Channel Dwell Times
    Minimum...................................... unknown
    Average...................................... unknown
    Maximum...................................... unknown
  Auto-RF Allowed Channel List................... 36,40,44,48,52,56,60,64,100,
    ............................................. 104,108,112,116,132,136,140,
    ............................................. 149,153,157,161
  Auto-RF Unused Channel List................. 165,190,196 

coverage—Shows the coverage hole detection configuration and statistics.

Coverage Hole Detection
  802.11a Coverage Hole Detection Mode........... Enabled
  802.11a Coverage Voice Packet Count............ 10 packets
  802.11a Coverage Voice Packet Percentage....... 20%
  802.11a Coverage Voice RSSI Threshold.......... -75 dBm
  802.11a Coverage Data Packet Count............. 10 packets
  802.11a Coverage Data Packet Percentage........ 20%
  802.11a Coverage Data RSSI Threshold........... -80 dBm
  802.11a Global coverage exception level........ 25%
  802.11a Global client minimum exception lev. 3 clients 

logging—Shows the RF event and performance logging.

RF Event and Performance Logging
  Channel Update Logging......................... Off
  Coverage Profile Logging....................... Off
  Foreign Profile Logging........................ Off
  Load Profile Logging........................... Off
  Noise Profile Logging.......................... Off
  Performance Profile Logging.................... Off
  TxPower Update Logging...................... Off 

monitor—Shows the Cisco radio monitoring.

Default 802.11a AP monitoring
  802.11a Monitor Mode........................... enable
  802.11a Monitor Channels....................... Country channels
  802.11a AP Coverage Interval................... 180 seconds
  802.11a AP Load Interval....................... 60 seconds
  802.11a AP Noise Interval...................... 180 seconds
  802.11a AP Signal Strength Interval......... 60 seconds 

profile {global | Cisco_AP}—Shows the access point performance profiles.

Default 802.11a AP performance profiles
  802.11a Global Interference threshold.......... 10%
  802.11a Global noise threshold................. -70 dBm
  802.11a Global RF utilization threshold........ 80%
  802.11a Global throughput threshold............ 1000000 bps
  802.11a Global clients threshold............ 12 clients 

receiver—Shows the 802.11a or 802.11b/g receiver configuration and statistics.

802.11a Advanced Receiver Settings                                  
 RxStart  : Signal Threshold..................... 15                            
 RxStart  : Signal Jump Threshold................ 5
 RxStart  : Preamble Power Threshold............. 2
 RxRestart: Signal Jump Status................... Enabled
 RxRestart: Signal Jump Threshold................ 10
 TxStomp  : Low RSSI Status...................... Enabled
 TxStomp  : Low RSSI Threshold................... 30
 TxStomp  : Wrong BSSID Status................... Enabled
 TxStomp  : Wrong BSSID Data Only Status......... Enabled
 RxAbort  : Raw Power Drop Status................ Disabled
 RxAbort  : Raw Power Drop Threshold............. 10
 RxAbort  : Low RSSI Status...................... Disabled
 RxAbort  : Low RSSI Threshold................... 0
 RxAbort  : Wrong BSSID Status................... Disabled
 RxAbort  : Wrong BSSID Data Only Status......... Disabled
 --------------------------------------------....
 pico-cell-V2 parameters in dbm units:...........

 RxSensitivity: Min,Max,Current RxSense Thres.... 0,0,0
 CCA Threshold: Min,Max,Current Clear Channel.... 0,0,0
Tx Pwr: Min,Max,Current Transmit Power for A.... 0,0,0
 --------------------------------------------.... 

summary—Shows the configuration and statistics of the 802.11a or 802.11b/g access points

AP Name                          Channel     TxPower Level
-------------------------------- ----------- -------------
AP1242.47b2.31f6                    132*           1*
AP0016.47b2.31ea                    132*           1*
AP1131:46f2.98ac 		 	 	 	 	 	 	 	64*           1* 

txpower—Shows the transmit power assignment configuration and statistics.

Automatic Transmit Power Assignment
  Transmit Power Assignment Mode................. AUTO
  Transmit Power Update Interval................. 600 seconds
  Transmit Power Threshold....................... -65 dBm
  Transmit Power Neighbor Count.................. 3 APs
  Transmit Power Update Contribution............. SNI.
  Transmit Power Assignment Leader............... 00:0b:85:43:dd:c0
  Last Run....................................... 360 seconds ago

Using the CLI to Debug RRM Issues

Use these commands to troubleshoot and verify RRM behavior:

debug airewave-director ?

where ? is one of the following:

all—Enables debugging for all RRM logs.

channel—Enables debugging for the RRM channel assignment protocol.

detail—Enables debugging for RRM detail logs.

error—Enables debugging for RRM error logs.

group—Enables debugging for the RRM grouping protocol.

manager—Enables debugging for the RRM manager.

message—Enables debugging for RRM messages.

packet—Enables debugging for RRM packets.

power—Enables debugging for the RRM power assignment protocol as well as coverage hole detection.

profile—Enables debugging for RRM profile events.

radar—Enables debugging for the RRM radar detection/avoidance protocol.

rf-change—Enables debugging for RRM RF changes.

Overriding RRM

In some deployments, it is desirable to statically assign channel and transmit power settings to the access points instead of relying on the RRM algorithms provided by Cisco. Typically, this is true in challenging RF environments and non-standard deployments but not the more typical carpeted offices.


Note If you choose to statically assign channels and power levels to your access points and/or to disable dynamic channel and power assignment, you should still use automatic RF grouping to avoid spurious rogue device events.


You can disable dynamic channel and power assignment globally for a controller, or you can leave dynamic channel and power assignment enabled and statically configure specific access point radios with a channel and power setting. Follow the instructions in one of the following sections:

Statically Assigning Channel and Transmit Power Settings to Access Point Radios

Disabling Dynamic Channel and Power Assignment Globally for a Controller


Note While you can specify a global default transmit power parameter for each network type that applies to all the access point radios on a controller, you must set the channel for each access point radio when you disable dynamic channel assignment. You may also want to set the transmit power for each access point instead of leaving the global transmit power in effect.



Note You can also override RRM using the Cisco Wireless Control System (WCS). Refer to the Cisco Wireless Control System Configuration Guide for instructions.


Statically Assigning Channel and Transmit Power Settings to Access Point Radios

This section provides instructions for statically assigning channel and power settings using the GUI or CLI.


Note Cisco recommends that you assign different nonoverlapping channels to access points that are within close proximity to each other. The nonoverlapping channels in the U.S. are 36, 40, 44, 48, 52, 56, 60, 64, 149, 153, 157, and 161 in an 802.11a network and 1, 6, and 11 in an 802.11b/g network.



Note Cisco recommends that you do not assign all access points that are within close proximity to each other to the maximum power level.


Using the GUI to Statically Assign Channel and Transmit Power Settings

Follow these steps to statically assign channel and/or power settings on a per access point radio basis using the GUI.


Step 1 Click Wireless > Access Points > Radios > 802.11a/n or 802.11b/g/n to open the 802.11a/n (or 802.11b/g/n) Radios page (see Figure 10-7).

Figure 10-7 802.11a/n Radios Page

This page shows all the 802.11a/n or 802.11b/g/n access point radios that are joined to the controller and their current settings.

Step 2 Hover your cursor over the blue drop-down arrow for the access point for which you want to modify the radio configuration and choose Configure. The 802.11a/n (or 802.11b/g/n) Cisco APs > Configure page appears (see Figure 10-8).

Figure 10-8 802.11a/n Cisco APs > Configure Page

Step 3 To assign an RF channel to the access point radio, choose Custom for the Assignment Method under RF Channel Assignment and choose a channel from the drop-down box.


Note Changing the operating channel causes the access point radio to reset.


Step 4 To assign a transmit power level to the access point radio, choose Custom for the Assignment Method under Tx Power Level Assignment and choose a transmit power level from the drop-down box.

The transmit power level is assigned an integer value instead of a value in mW or dBm. The integer corresponds to a power level that varies depending on the regulatory domain in which the access points are deployed. The number of available power levels varies based on the access point model. However, power level 1 is always the maximum power level allowed per country code setting, with each successive power level representing 50% of the previous power level. For example, 1 = maximum power level in a particular regulatory domain, 2 = 50% power, 3 = 25% power, 4 = 12.5% power, and so on.


Note Refer to the hardware installation guide for your access point for the maximum transmit power levels supported per regulatory domain. Also, refer to the data sheet for your access point for the number of power levels supported.


Step 5 Click Apply to commit your changes.

Step 6 Click Save Configuration to save the changes to the access point radio.

Step 7 Repeat this procedure for each access point radio for which you want to assign a static channel and power level.


Using the CLI to Statically Assign Channel and Transmit Power Settings

Follow these steps to statically assign channel and/or power settings on a per access point radio basis using the CLI.


Step 1 Enter this command to disable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} disable

Step 2 To specify the channel that a particular access point is to use, enter this command:

config {802.11a | 802.11b} channel Cisco_AP channel

Example: To configure 802.11a channel 36 as the default channel on AP1, enter this command:
config 802.11a channel AP1 36.


Note Changing the operating channel causes the access point radio to reset.


Step 3 To specify the transmit power level that a particular access point is to use, enter this command:

config {802.11a | 802.11b} txPower Cisco_AP power_level

Example: To set the transmit power for 802.11a AP1 to power level 2, enter this command:
config 802.11a txPower AP1 2.

The transmit power level is assigned an integer value instead of a value in mW or dBm. The integer corresponds to a power level that varies depending on the regulatory domain in which the access points are deployed. The number of available power levels varies based on the access point model. However, power level 1 is always the maximum power level allowed per country code setting, with each successive power level representing 50% of the previous power level. For example, 1 = maximum power level in a particular regulatory domain, 2 = 50% power, 3 = 25% power, 4 = 12.5% power, and so on.


Note Refer to the hardware installation guide for your access point for the maximum transmit power levels supported per regulatory domain. Also, refer to the data sheet for your access point for the number of power levels supported.


Step 4 Enter this command to save your settings:

save config

Step 5 Repeat Step 2 through Step 4 for each access point radio for which you want to assign a static channel and power level.

Step 6 Enter this command to enable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} enable


Note To enable the 802.11g network, enter config 802.11b 11gSupport enable after the config 802.11b enable command.


Step 7 Enter this command to save your settings:

save config


Disabling Dynamic Channel and Power Assignment Globally for a Controller

This section provides instructions for disabling dynamic channel and power assignment using the GUI or CLI.

Using the GUI to Disable Dynamic Channel and Power Assignment

Follow these steps to configure disable dynamic channel and power assignment using the GUI.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > RRM > Auto RF to open the 802.11a (or 802.11b/g) Global Parameters > Auto RF page (see Figure 10-2).

Step 2 To disable dynamic channel assignment, choose Off under RF Channel Assignment.

Step 3 To disable dynamic power assignment, choose Fixed under Tx Power Level Assignment and choose a default transmit power level from the drop-down box.


Note See Step 4 on page 10-26 for information on transmit power levels.


Step 4 Click Apply to commit your changes.

Step 5 Click Save Configuration to save your changes.

Step 6 If you are overriding the default channel and power settings on a per radio basis, assign static channel and power settings to each of the access point radios that are joined to the controller.

Step 7 If desired, repeat this procedure for the network type you did not select (802.11a or 802.11b/g).


Using the CLI to Disable Dynamic Channel and Power Assignment

Follow these steps to disable RRM for all 802.11a or 802.11b/g radios.


Step 1 Enter this command to disable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} disable

Step 2 Enter this command to disable RRM for all 802.11a or 802.11b/g radios and set all channels to the default value:

config {802.11a | 802.11b} channel global off

Step 3 Enter this command to enable the 802.11a or 802.11b/g network:

config {802.11a | 802.11b} enable


Note To enable the 802.11g network, enter config 802.11b 11gSupport enable after the config 802.11b enable command.


Step 4 Enter this command to save your settings:

save config


Enabling Rogue Access Point Detection in RF Groups

After you have created an RF group of controllers, you need to configure the access points connected to the controllers to detect rogue access points. The access points will then check the beacon/
probe-response frames in neighboring access point messages to see if they contain an authentication information element (IE) that matches that of the RF group. If the check is successful, the frames are authenticated. Otherwise, the authorized access point reports the neighboring access point as a rogue, records its BSSID in a rogue table, and sends the table to the controller.

Using the GUI to Enable Rogue Access Point Detection in RF Groups

Using the controller GUI, follow these steps to enable rogue access point detection in RF groups.


Step 1 Make sure that each controller in the RF group has been configured with the same RF group name.


Note The name is used to verify the authentication IE in all beacon frames. If the controllers have different names, false alarms will occur.


Step 2 Click Wireless to open the All APs page (see Figure 10-9).

Figure 10-9 All APs Page

Step 3 Click the name of an access point to open the All APs > Details page (see Figure 10-10).

Figure 10-10 All APs > Details Page

Step 4 Choose either local or monitor from the AP Mode drop-down box and click Apply to commit your changes.

Step 5 Click Save Configuration to save your changes.

Step 6 Repeat Step 2 through Step 5 for every access point connected to the controller.

Step 7 Click Security > Wireless Protection Policies > AP Authentication/MFP to open the AP Authentication Policy page (see Figure 10-11).

Figure 10-11 AP Authentication Policy Page

The name of the RF group to which this controller belongs appears at the top of the page.

Step 8 Choose AP Authentication from the Protection Type drop-down box to enable rogue access point detection.

Step 9 Enter a number in the Alarm Trigger Threshold edit box to specify when a rogue access point alarm is generated. An alarm occurs when the threshold value (which specifies the number of access point frames with an invalid authentication IE) is met or exceeded within the detection period.


Note The valid threshold range is from1 to 255, and the default threshold value is 1. To avoid false alarms, you may want to set the threshold to a higher value.


Step 10 Click Apply to commit your changes.

Step 11 Click Save Configuration to save your changes.

Step 12 Repeat this procedure on every controller in the RF group.


Note If rogue access point detection is not enabled on every controller in the RF group, the access points on the controllers with this feature disabled are reported as rogues.



Using the CLI to Enable Rogue Access Point Detection in RF Groups

Using the controller CLI, follow these steps to enable rogue access point detection in RF groups.


Step 1 Make sure that each controller in the RF group has been configured with the same RF group name.


Note The name is used to verify the authentication IE in all beacon frames. If the controllers have different names, false alarms will occur.


Step 2 Enter config ap mode local Cisco_AP or config ap mode monitor Cisco_AP to configure this particular access point for local (normal) mode or monitor (listen-only) mode.

Step 3 Enter save config to save your settings.

Step 4 Repeat Step 2 and Step 3 for every access point connected to the controller.

Step 5 Enter config wps ap-authentication to enable rogue access point detection.

Step 6 Enter config wps ap-authentication threshold to specify when a rogue access point alarm is generated. An alarm occurs when the threshold value (which specifies the number of access point frames with an invalid authentication IE) is met or exceeded within the detection period.


Note The valid threshold range is from1 to 255, and the default threshold value is 1. To avoid false alarms, you may want to set the threshold to a higher value.


Step 7 Enter save config to save your settings.

Step 8 Repeat Step 5 through Step 7 on every controller in the RF group.


Note If rogue access point detection is not enabled on every controller in the RF group, the access points on the controllers with this feature disabled are reported as rogues.



Configuring CCX Radio Management Features

You can configure two parameters that affect client location calculations:

Radio measurement requests

Location calibration

These parameters are supported in Cisco Client Extensions (CCX) v2 and higher and are designed to enhance location accuracy and timeliness for participating CCX clients. See the "Configuring Cisco Client Extensions" section on page 6-38 for more information on CCX.

For the location features to operate properly, the access points must be configured for normal, monitor, or hybrid-REAP mode. However, for hybrid-REAP mode, the access point must be connected to the controller.


Note CCX is not supported on the AP1030.


Radio Measurement Requests

When this feature is enabled, lightweight access points issue broadcast radio measurement request messages to clients running CCXv2 or higher. The access points transmit these messages for every SSID over each enabled radio interface at a configured interval. In the process of performing 802.11 radio measurements, CCX clients send 802.11 broadcast probe requests on all the channels specified in the measurement request. The Cisco Location Appliance uses the uplink measurements based on these requests received at the access points to quickly and accurately calculate the client location. You do not need to specify on which channels the clients are to measure. The controller, access point, and client automatically determine which channels to use.

In controller software release 4.1 or later, the radio measurement feature has been expanded to enable the controller to also obtain information on the radio environment from the client's perspective (rather than from just that of the access point). In this case, the access points issue unicast radio measurement requests to a particular CCXv4 or v5 client. The client then sends various measurement reports back to the access point and onto the controller. These reports include information on the radio environment and data used to interpret the location of the clients. To prevent the access points and controller from being overwhelmed by radio measurement requests and reports, only two clients per access point and up to twenty clients per controller are supported. You can view the status of radio measurement requests for a particular access point or client as well as radio measurement reports for a particular client from the controller CLI.

Controller software release 4.1 or later also improves the ability of the Location Appliance to accurately interpret the location of a device through a new CCXv4 feature called location-based services. The controller issues a path-loss request to a particular CCXv4 or v5 client. If the client chooses to respond, it sends a path-loss measurement report to the controller. These reports contain the channel and transmit power of the client.


Note Non-CCX and CCXv1 clients simply ignore the CCX measurement requests and therefore do not participate in the radio measurement activity.


Location Calibration

For CCX clients that need to be tracked more closely (for example, when a client calibration is performed), the controller can be configured to command the access point to send unicast measurement requests to these clients at a configured interval and whenever a CCX client roams to a new access point. These unicast requests can be sent out more often to these specific CCX clients than the broadcast measurement requests, which are sent to all clients. When location calibration is configured for non-CCX and CCXv1 clients, the clients are forced to disassociate at a specified interval to generate location measurements.

Using the GUI to Configure CCX Radio Management

Follow these steps to configure CCX radio management using the controller GUI.


Step 1 Click Wireless > 802.11a/n or 802.11b/g/n > Network. The 802.11a (or 802.11b/g) Global Parameters page appears (see Figure 10-12).

Figure 10-12 802.11a Global Parameters Page

Step 2 Under CCX Location Measurement, check the Mode check box to globally enable CCX radio management. This parameter causes the access points connected to this controller to issue broadcast radio measurement requests to clients running CCX v2 or higher. The default value is disabled (or unchecked).

Step 3 If you checked the Mode check box in the previous step, enter a value in the Interval field to specify how often the access points are to issue the broadcast radio measurement requests.

Range: 60 to 32400 seconds

Default: 60 seconds

Step 4 Click Apply to commit your changes.

Step 5 Click Save Configuration to save your settings.

Step 6 Follow the instructions in Step 2 of the "Using the CLI to Configure CCX Radio Management" section below to enable access point customization.


Note To enable CCX radio management for a particular access point, you must enable access point customization, which can be done only through the controller CLI.


Step 7 If desired, repeat this procedure for the other radio band (802.11a or 802.11b/g).


Using the CLI to Configure CCX Radio Management

Follow these steps to enable CCX radio management using the controller CLI.


Step 1 To globally enable CCX radio management, enter this command:

config advanced {802.11a | 802.11b} ccx location-meas global enable interval_seconds

The range for the interval_seconds parameter is 60 to 32400 seconds, and the default value is 60 seconds. This command causes all access points connected to this controller in the 802.11a or 802.11b/g network to issue broadcast radio measurement requests to clients running CCXv2 or higher.

Step 2 To enable access point customization, enter these commands:

config advanced {802.11a | 802.11b} ccx customize Cisco_AP {on | off}

This command enables or disables CCX radio management features for a particular access point in the 802.11a or 802.11b/g network.

config advanced {802.11a | 802.11b} ccx location-meas ap Cisco_AP enable interval_seconds

The range for the interval_seconds parameter is 60 to 32400 seconds, and the default value is 60 seconds. This command causes a particular access point in the 802.11a or 802.11b/g network to issue broadcast radio measurement requests to clients running CCXv2 or higher.

Step 3 To enable or disable location calibration for a particular client, enter this command:

config client location-calibration {enable | disable} client _mac interval_seconds


Note You can configure up to five clients per controller for location calibration.


Step 4 To save your settings, enter this command:

save config


Using the CLI to Obtain CCX Radio Management Information

Use these commands to obtain information about CCX radio management on the controller.

1. To see the CCX broadcast location measurement request configuration for all access points connected to this controller in the 802.11a or 802.11b/g network, enter this command:

show advanced {802.11a | 802.11b} ccx global

2. To see the CCX broadcast location measurement request configuration for a particular access point in the 802.11a or 802.11b/g network, enter this command:

show advanced {802.11a | 802.11b} ccx ap Cisco_AP

3. To see the status of radio measurement requests for a particular access point, enter this command:

show ap ccx rm Cisco_AP status

Information similar to the following appears:

A Radio

  Beacon Request................................. Enabled
  Channel Load Request........................... Enabled
  Frame Request.................................. Disabled
  Noise Histogram Request........................ Disabled
  Path Loss Request.............................. Disabled
  Interval....................................... 60
  Iteration...................................... 5

B Radio

  Beacon Request................................. Disabled
  Channel Load Request........................... Enabled
  Frame Request.................................. Disabled
  Noise Histogram Request........................ Enabled
  Path Loss Request.............................. Disabled
  Interval....................................... 60
  Iteration................................... 5 

4. To see the status of radio measurement requests for a particular client, enter this command:

show client ccx rm client_mac status

Information similar to the following appears:

Client Mac Address............................... 00:40:96:ae:53:b4
Beacon Request................................... Enabled
Channel Load Request............................. Disabled
Frame Request.................................... Disabled
Noise Histogram Request.......................... Disabled
Path Loss Request................................ Disabled
Interval......................................... 5
Iteration........................................ 3

5. To see radio measurement reports for a particular client, enter these commands:

show client ccx rm client_mac report beacon—Shows the beacon report for the specified client.

show client ccx rm client_mac report chan-load—Shows the channel-load report for the specified client.

show client ccx rm client_mac report noise-hist—Shows the noise-histogram report for the specified client.

show client ccx rm client_mac report frame—Shows the frame report for the specified client.

6. To see the clients configured for location calibration, enter this command:

show client location-calibration summary

7. To see the RSSI reported for both antennas on each access point that heard the client, enter this command:

show client detail client_mac

Using the CLI to Debug CCX Radio Management Issues

Use these commands if you experience any CCX radio management problems.

1. To debug CCX broadcast measurement request activity, enter this command:

debug airewave-director message {enable | disable}

2. To debug client location calibration activity, enter this command:

debug ccxrm [all | error | warning | message | packet | detail {enable | disable}]

3. The CCX radio measurement report packets are encapsulated in Internet Access Point Protocol (IAPP) packets. Therefore, if the previous debug ccxrm command does not provide any debugs, enter this command to provide debugs at the IAPP level:

debug iapp error {enable | disable}

4. To debug the output for forwarded probes and their included RSSI for both antennas, enter this command:

debug dot11 load-balancing

Configuring Pico Cell Mode

In large multi-cell high-density wireless networks, it can be challenging to populate a site with a large number of access points to handle the desired cumulative bandwidth load while diminishing the contention between access points and maintaining quality of service. To optimize RF channel capacity and improve overall network performance, you can use the controller GUI or CLI to set high-density (or pico cell) mode parameters.

These parameters enable you to apply the same receiver sensitivity threshold, clear channel assessment (CCA) sensitivity threshold, and transmit power values across all access points registered to a given controller. When a client that supports high density associates to an access point with high density enabled, they exchange specific 802.11 information elements (IEs) that instruct the client to adhere to the access point's advertised receive sensitivity threshold, CCA sensitivity threshold, and transmit power values. These three parameters reduce the effective cell size by adjusting the received signal strength before an access point and client consider the channel accessible for the transfer of packets. When all access points and clients raise the signal standard in this way throughout a high-density area, access points can be deployed closer together without interfering with each other or being overwhelmed by environmental and distant-rogue signals.

The benefits of a high-density-enabled wireless network include the following:

Most efficient use of the available spectrum

Significant increase in aggregate client throughput or throughput per square feet

Significant increase in wireless LAN capacity

Linear capacity growth

Higher interference tolerance by allowing WiFi to transmit over top of the interference

Figure 10-13 shows an example of a high-density network.

Figure 10-13 High-Density Network Example

Guidelines for Using Pico Cell Mode

Follow these guidelines for using pico cell mode:

High-density networking is supported on Cisco lightweight access points and on notebooks using the Intel PRO/Wireless 3945ABG and Intel Wireless WiFi Link 4965AG clients.

In order to use pico cell mode version 2, the WMM policy for the Intel clients must be set to Allowed.

To support high-density, both the client s and access points must be configured for high density. Do not mix high-density and non-high-density devices in the same network.

High-density access points must be joined to a dedicated controller.

When you adjust the pico cell mode parameters, the following RRM values automatically change:

The default value of the Fixed option for the Power Level Assignment Method parameter [on the 802.11a (or 802.11b) > RRM > Tx Power Control (TPC) page] reflects the power setting that you specify for the pico cell Transmit Power parameter.

The default value of the Power Threshold parameter [on the 802.11a (or 802.11b) > RRM > Tx Power Control (TPC) page] reflects the value that you specify for the pico cell CCA Sensitivity Threshold parameter.

Using the GUI to Configure Pico Cell Mode

Follow these steps to configure pico cell mode using the controller GUI.


Step 1 Disable the 802.11a or 802.11b/g network before changing pico cell mode parameters. To do so, click Wireless > 802.11a/n (or 802.11b/g/n) > Network and uncheck the 802.11a Network Status (or 802.11b/g Network Status) check box.

Step 2 Click Wireless > 802.11a/n (or 802.11b/g/n) > Pico Cell to open the 802.11a (or 802.11b/g) > Pico Cell page (see Figure 10-14).

Figure 10-14 802.11a > Pico Cell Page

Step 3 Choose one of these options from the Pico Cell Mode drop-down box:

Disable—Disables pico cell mode. This is the default value.

V1—Enables pico cell mode version 1. This option is designed for use with legacy Airespace products (those released prior to Cisco's acquisition of Airespace). Cisco recommends that you choose V2 if you want to enable pico cell mode.

V2—Enables pico cell mode version 2. Choose this option if you want to adjust the pico cell mode parameters to optimize network performance in high-density areas, where all the clients support high density.

Step 4 If you chose V2 in Step 3, the 802.11a (or 802.11b/g) > Pico Cell page displays three configurable fields: Rx Sensitivity Threshold, CCA Sensitivity Threshold, and Transmit Power (see Figure 10-15).

Figure 10-15 802.11a > Pico Cell Page with Pico Cell Mode V2 Parameters

Use the information in Table 10-2 to adjust the values of these parameters as necessary.


Note The default values for these parameters should be appropriate for most applications. Therefore, Cisco recommends that you use the default values.

Table 10-2 Pico Cell Mode V2 Parameters

Parameter
Description

Rx Sensitivity Threshold

Specifies the current, minimum, and maximum values (in dBm) for the receiver sensitivity of the 802.11a or 802.11b/g radio. The current value sets the receiver sensitivity on the local radio. The min and max values are used only for inclusion in the Inter-Access Point Protocol (IAPP) high-density reports.

Default: -65 dBm (Current), -127 dBm (Min), and 127 dBm (Max)

CCA Sensitivity Threshold

Specifies the clear channel assessment (CCA) sensitivity threshold on all radios in the high-density cell. The current value programs the 802.11a or 802.11b/g receiver. The min and max values are for advertisement in IAPP reports.

Default: -65 dBm (Current), -127 dBm (Min), and 127 dBm (Max)

Transmit Power

Specifies the high-density transmit power used by both the access point and client 802.11a or 802.11b/g radios.

Default: 10 dBm (Current), -127 dBm (Min), and 127 dBm (Max)




Note The min and max values in Figure 10-15 and Table 10-2 are used only to indicate the range to the client. They are not used on the access point.


Step 5 Click Apply to commit your changes.

Step 6 Re-enable the 802.11a or 802.11b/g network. To do so, click Wireless > 802.11a/n (or 802.11b/g/n) > Network and check the 802.11a Network Status (or 802.11b/g Network Status) check box.

Step 7 Click Save Configuration to save your changes.


Note If you change the values of the pico cell mode parameters and later want to reset them to their default values, click Reset to Defaults and then click Apply.



Using the CLI to Configure Pico Cell Mode


Note Refer to the "Using the GUI to Configure Pico Cell Mode" section for descriptions and default values of the parameters used in the CLI commands.



Step 1 To disable the 802.11a or 802.11b/g network before changing pico cell mode parameters, enter this command:

config {802.11a | 802.11b} disable

Step 2 To enable pico cell mode, enter one of these commands:

config {802.11a | 802.11b} picocell enableEnables pico cell mode version 1. This command is designed for use with a specific application. Cisco recommends that you use the config {802.11a | 802.11b} picocell-V2 enable command if you want to enable pico cell mode.

config {802.11a | 802.11b} picocell-V2 enable—Enables pico cell mode version 2. Use this command if you want to adjust the pico cell mode parameters to optimize network performance in high-density areas.

Step 3 If you enabled pico cell mode version 2 in Step 2, follow these steps to configure the receive sensitivity threshold, CCA sensitivity threshold, and transmit power parameters:

a. To configure the receive sensitivity threshold, enter this command:

config advanced {802.11a | 802.11b} receiver pico-cell-V2 rx_sense_threshold min max current

b. To configure the CCA sensitivity threshold, enter this command:

config advanced {802.11a | 802.11b} receiver pico-cell-V2 cca_sense_threshold min max current

c. To configure the transmit power, enter this command:

config advanced {802.11a | 802.11b} receiver pico-cell-V2 sta_tx_pwr min max current

Step 4 If you enabled pico cell mode version 2 in Step 2 and you want to transmit a unicast IAPP high-density frame request to a specific client, enter this command:

config advanced {802.11a | 802.11b} receiver pico-cell-V2 send_iapp_req client_mac

Step 5 To re-enable the 802.11a or 802.11b/g network, enter this command:

config {802.11a | 802.11b} enable

Step 6 To save your settings, enter this command:

save config


Using the CLI to Debug Pico Cell Mode Issues

Use these commands if you experience any pico cell mode problems.

1. To see the current status of pico cell mode, enter this command:

show {802.11a | 802.11b}

Information similar to the following appears:

802.11a Network.................................. Disabled
11nSupport....................................... Disabled
      802.11a Low Band........................... Enabled
      802.11a Mid Band........................... Enabled
      802.11a High Band.......................... Enabled
...
Pico-Cell Status................................. Disabled
Pico-Cell-V2 Status........................... Enabled 

2. To see the receiver parameters that are set by the pico cell mode commands, enter this command:

show advanced {802.11a | 802.11b} receiver

Information similar to the following appears:

802.11a Advanced Receiver Settings
 RxStart  : Signal Threshold..................... 30
 RxStart  : Signal Jump Threshold................ 5
 RxStart  : Preamble Power Threshold............. 30
 RxRestart: Signal Jump Status................... Enabled
 RxRestart: Signal Jump Threshold................ 10
 TxStomp  : Low RSSI Status...................... Disabled
 TxStomp  : Low RSSI Threshold................... 30
 TxStomp  : Wrong BSSID Status................... Disabled
 TxStomp  : Wrong BSSID Data Only Status......... Disabled
 RxAbort  : Raw Power Drop Status................ Disabled
 RxAbort  : Raw Power Drop Threshold............. 10
 RxAbort  : Low RSSI Status...................... Disabled
 RxAbort  : Low RSSI Threshold................... 30
 RxAbort  : Wrong BSSID Status................... Disabled
 RxAbort  : Wrong BSSID Data Only Status......... Disabled
 --------------------------------------------....
 pico-cell-V2 parameters in dbm units:
 RxSensitivity: Min,Max,Current RxSense Thres.... -127,127,-65
 CCA Threshold: Min,Max,Current Clear Channel.... -127,127,-65
Tx Pwr: Min,Max,Current Transmit Power for A..... -127,127,10
 --------------------------------------------.... 

3. To see the noise and interference information, coverage information, client signal strengths and signal-to-noise ratios, and nearby access points, enter this command:

show ap auto-rf {802.11a | 802.11b} Cisco_AP

Information similar to the following appears:

Number Of Slots.................................. 2
AP Name.......................................... AP1242.47b2.31f6
MAC Address...................................... 00:16:47:b2:31:f6
  Radio Type..................................... RADIO_TYPE_80211a
  Noise Information
    Noise Profile................................ PASSED
  Interference Information
    Interference Profile......................... PASSED
  Load Information
    Load Profile................................. PASSED
    Receive Utilization.......................... 0 %
    Transmit Utilization......................... 0 %
    Channel Utilization.......................... 0 %
    Attached Clients............................. 0 clients
  Coverage Information
    Coverage Profile............................. PASSED
    Failed Clients............................... 0 clients
  Client Signal Strengths
    RSSI -100 dbm................................ 0 clients
    RSSI  -92 dbm................................ 0 clients
    RSSI  -84 dbm................................ 0 clients
	RSSI  -76 dbm................................ 0 clients
    RSSI  -68 dbm................................ 0 clients
    RSSI  -60 dbm................................ 0 clients
    RSSI  -52 dbm................................ 0 clients
  Client Signal To Noise Ratios
    SNR    0 dB.................................. 0 clients
    SNR    5 dB.................................. 0 clients
    SNR   10 dB.................................. 0 clients
    SNR   15 dB.................................. 0 clients
    SNR   20 dB.................................. 0 clients
    SNR   25 dB.................................. 0 clients
    SNR   30 dB.................................. 0 clients
    SNR   35 dB.................................. 0 clients
    SNR   40 dB.................................. 0 clients
    SNR   45 dB.................................. 0 clients
  Nearby APs
  Radar Information
  RF Parameter Recommendations
    Power Level.................................. 0
    RTS/CTS Threshold............................ 0
    Fragmentation Threshold...................... 0
    Antenna Pattern.............................. 0