Call Admission Control
This section contains the following subsections:
Voice and Video Parameters
Three parameters on the controller affect voice and/or video quality:
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Call admission control
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Expedited bandwidth requests
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Unscheduled automatic power save delivery
Each of these parameters is supported in Cisco Compatible Extensions (CCX) v4 and v5.
This section contains the following subsections:
Configuring Voice Parameters
Configuring Voice Parameters (GUI)
Procedure
Step 1 |
Ensure that the WLAN is configured for WMM and the Platinum QoS level. |
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Step 2 |
Choose Wireless and then Network under 802.11a/n/ac or 802.11b/g/n, uncheck the 802.11a (or 802.11b/g) Network Status check box, and click Apply to disable the radio network. |
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Step 3 |
Choose Wireless > 802.11a/n/ac or 802.11b/g/n > Media. The 802.11a (or 802.11b) > Media page appears. The Voice tab is displayed by default. |
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Step 4 |
(Optional) Check the Admission Control (ACM) check box to enable static CAC for this radio band. The default value is disabled. |
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Step 5 |
(Optional) Select the Admission Control (ACM) you want to use by choosing from the following choices:
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Step 6 |
In the Max RF Bandwidth field, enter the percentage of the maximum bandwidth allocated to clients for voice applications on this radio band. Once the client reaches the value specified, the access point rejects new calls on this radio band. The range is 5% to 85%. The sum of maximum bandwidth percentage of voice and video should not exceed 85%. The default is 75%. |
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Step 7 |
In the Reserved Roaming Bandwidth field, enter the percentage of maximum allocated bandwidth that is reserved for roaming voice clients. The controller reserves this bandwidth from the maximum allocated bandwidth for roaming voice clients. The range is 0% to 25%. The default is 6%. |
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Step 8 |
To enable expedited bandwidth requests, check the Expedited Bandwidth check box. By default, this field is disabled. |
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Step 9 |
To enable SIP CAC support, check the SIP CAC Support check box. By default, SIP CAC support is disabled. |
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Step 10 |
From the SIP Codec drop-down list, choose one of the following options to set the codec name. The default value is G.711. The options are as follows:
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Step 11 |
In the SIP Bandwidth (kbps) field, enter the bandwidth in kilobits per second. The possible range is 8 to 64. The default value is 64.
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Step 12 |
In the SIP Voice Sample Interval (msecs) field, enter the value for the sample interval. |
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Step 13 |
In the Maximum Calls field, enter the maximum number of calls that can be made to this radio. The maximum call limit includes both direct and roaming-in calls. If the maximum call limit is reached, the new or roaming-in calls result in failure. The possible range is 0 to 25. The default value is 0, which indicates that there is no check for maximum call limit.
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Step 14 |
Check the Metrics Collection check box to collect traffic stream metrics. By default, this box is unselected. That is, the traffic stream metrics is not collected by default. |
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Step 15 |
Click Apply. |
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Step 16 |
Choose Network under 802.11a/n/ac or 802.11b/g/n, check the 802.11a (or 802.11b/g) Network Status check box, and click Apply to reenable the radio network. |
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Step 17 |
Click Save Configuration. |
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Step 18 |
Repeat this procedure if you want to configure voice parameters for another radio band. |
Configuring Voice Parameters (CLI)
Before you begin
Ensure that you have configured SIP-based CAC.
Procedure
Step 1 |
See all of the WLANs configured on the controller by entering this command: show wlan summary |
Step 2 |
Make sure that the WLAN that you are planning to modify is configured for WMM and the QoS level is set to Platinum by entering this command: show wlan wlan_id |
Step 3 |
Disable the radio network by entering this command: config {802.11a | 802.11b} disable network |
Step 4 |
Save your settings by entering this command: save config |
Step 5 |
Enable or disable static CAC for the 802.11a or 802.11b/g network by entering this command: config {802.11a | 802.11b} cac voice acm {enable | disable} |
Step 6 |
Set the percentage of maximum bandwidth allocated to clients for voice applications on the 802.11a or 802.11b/g network by entering this command: config {802.11a | 802.11b} cac voice max-bandwidth bandwidth The bandwidth range is 5 to 85%, and the default value is 75%. Once the client reaches the value specified, the access point rejects new calls on this network. |
Step 7 |
Set the percentage of maximum allocated bandwidth reserved for roaming voice clients by entering this command: config {802.11a | 802.11b} cac voice roam-bandwidth bandwidth The bandwidth range is 0 to 25%, and the default value is 6%. The controller reserves this much bandwidth from the maximum allocated bandwidth for roaming voice clients. |
Step 8 |
Configure the codec name and sample interval as parameters and to calculate the required bandwidth per call by entering this command: config {802.11a | 802.11b} cac voice sip codec {g711 | g729} sample-interval number_msecs |
Step 9 |
Configure the bandwidth that is required per call by entering this command: config {802.11a | 802.11b} cac voice sip bandwidth bandwidth_kbps sample-interval number_msecs |
Step 10 |
Reenable the radio network by entering this command: config {802.11a | 802.11b} enable network |
Step 11 |
View the TSM voice metrics by entering this command: show [802.11a | 802.11b] cu-metrics AP_Name The command also displays the channel utilization metrics. |
Step 12 |
Enter the save config command to save your settings. |
Step 13 |
Configure voice automatically for a WLAN by entering this command: config auto-configure voice cisco wlan-id radio {802.11a | 802.11b | all} |
Step 14 |
Enter the save config command to save your settings. |
Configuring Video Parameters
Configuring Video Parameters (GUI)
Procedure
Step 1 |
Ensure that the WLAN is configured for WMM and the Platinum or Gold QoS level. |
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Step 2 |
Choose Wireless and then Network under 802.11a/n/ac or 802.11b/g/n, uncheck the 802.11a (or 802.11b/g) Network Status check box, and click Apply to disable the radio network. |
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Step 3 |
Choose 802.11b/g/n > Media. The 802.11a (or 802.11b) > Media page appears. or |
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Step 4 |
In the Video tab, check the Admission Control (ACM) check box to enable video CAC for this radio band. The default value is disabled. |
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Step 5 |
From the CAC Method drop-down list, choose between Static and Load Based methods. The static CAC method is based on the radio and the load-based CAC method is based on the channel.
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Step 6 |
In the Max RF Bandwidth text box, enter the percentage of the maximum bandwidth allocated to clients for video applications on this radio band. When the client reaches the value specified, the access point rejects new requests on this radio band. The range is 5% to 85%. The sum of maximum bandwidth percentage of voice and video should not exceed 85%. The default is 0%. |
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Step 7 |
In the Reserved Roaming Bandwidth text box, enter the percentage of the maximum RF bandwidth that is reserved for roaming clients for video. |
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Step 8 |
Configure the SIP CAC Support by checking or unchecking the SIP CAC Support check box. SIP CAC is supported only if SIP Snooping is enabled.
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Step 9 |
Click Apply. |
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Step 10 |
Choose Network under 802.11a/n/ac or 802.11b/g/n, check the 802.11a (or 802.11b/g) Network Status check box, and click Apply to reenable the radio network. |
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Step 11 |
Click Save Configuration. |
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Step 12 |
Repeat this procedure if you want to configure video parameters for another radio band. |
Configuring Video Parameters (CLI)
Before you begin
Ensure that you have configured SIP-based CAC.
Procedure
Step 1 |
See all of the WLANs configured on the controller by entering this command: show wlan summary |
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Step 2 |
Make sure that the WLAN that you are planning to modify is configured for WMM and the QoS level is set to Gold by entering this command: show wlan wlan_id |
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Step 3 |
Disable the radio network by entering this command: config {802.11a | 802.11b} disable network |
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Step 4 |
Save your settings by entering this command: save config |
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Step 5 |
Enable or disable video CAC for the 802.11a or 802.11b/g network by entering this command: config {802.11a | 802.11b} cac video acm {enable | disable} |
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Step 6 |
To configure the CAC method as either static or load-based, enter this command: config {802.11a | 802.11b} cac video cac-method {static | load-based} |
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Step 7 |
Set the percentage of maximum bandwidth allocated to clients for video applications on the 802.11a or 802.11b/g network by entering this command: config {802.11a | 802.11b} cac video max-bandwidth bandwidth The bandwidth range is 5 to 85%, and the default value is 5%. However, the maximum RF bandwidth cannot exceed 85% for voice and video. Once the client reaches the value specified, the access point rejects new calls on this network.
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Step 8 |
To configure the percentage of the maximum RF bandwidth that is reserved for roaming clients for video, enter this command: config {802.11a | 802.11b} cac video roam-bandwidth bandwidth |
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Step 9 |
To configure the CAC parameters for SIP-based video calls, enter this command: config {802.11a | 802.11b} cac video sip {enable | disable} |
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Step 10 |
Process or ignore the TSPEC inactivity timeout received from an access point by entering this command: config {802.11a | 802.11b} cac video tspec-inactivity-timeout {enable | ignore} |
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Step 11 |
Reenable the radio network by entering this command: config {802.11a | 802.11b} enable network |
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Step 12 |
Enter the save config command to save your settings. |
Viewing Voice and Video Settings
Viewing Voice and Video Settings (GUI)
Procedure
Step 1 |
Choose Monitor > Clients to open the Clients page. |
Step 2 |
Click the MAC address of the desired client to open the Clients > Detail page. This page shows the U-APSD status (if enabled) for this client under Quality of Service Properties. |
Step 3 |
Click Back to return to the Clients page. |
Step 4 |
See the TSM statistics for a particular client and the access point to which this client is associated as follows: |
Step 5 |
See the TSM statistics for a particular access point and a particular client associated to this access point, as follows: |
Viewing Voice and Video Settings (CLI)
Procedure
Step 1 |
See the CAC configuration for the 802.11 network by entering this command: show ap stats {802.11a | 802.11b} |
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Step 2 |
See the CAC statistics for a particular access point by entering this command: show ap stats {802.11a | 802.11b} ap_name Information similar to the following appears:
In the example above, “MT” is medium time, “Na” is the number of additional calls, and “exp bw” is expedited bandwidth.
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Step 3 |
See the U-APSD status for a particular client by entering this command: show client detail client_mac |
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Step 4 |
See the TSM statistics for a particular client and the access point to which this client is associated by entering this command: show client tsm {802.11a | 802.11b} client_mac {ap_ma c | all} The optional all command shows all access points to which this client has associated. Information similar to the following appears:
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Step 5 |
See the TSM statistics for a particular access point and a particular client associated to this access point by entering this command: show ap stats {802.11a | 802.11b} ap_name tsm {client_mac | all} The optional all command shows all clients associated to this access point. Information similar to the following appears:
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Step 6 |
Enable or disable debugging for call admission control (CAC) messages, events, or packets by entering this command: debug cac {all | event | packet}{enable | disable} where all configures debugging for all CAC messages, event configures debugging for all CAC events, and packet configures debugging for all CAC packets. |
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Step 7 |
Use the following command to perform voice diagnostics and to view the debug messages between a maximum of two 802.11 clients: debug voice-diag {enable | disable} mac-id mac-id2 [verbose] The verbose mode is an optional argument. When the verbose option is used, all debug messages are displayed in the console. You can use this command to monitor a maximum of two 802.11 clients. If one of the clients is a non-WiFi client, only the 802.11 client is monitored for debug messages.
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Step 8 |
Use the following commands to view various voice-related parameters:
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Step 9 |
Use the following commands to troubleshoot video debug messages and statistics:
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Configuring SIP-Based CAC
Restrictions for SIP-Based CAC
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SIP CAC should only be used for phones that support status code 17 and do not support TSPEC-based admission control.
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SIP CAC will be supported only if SIP snooping is enabled.
Configuring SIP-Based CAC (GUI)
Before you begin
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Ensure that you have set the voice to the platinum QoS level.
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Ensure that you have enabled call snooping for the WLAN.
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Ensure that you have enabled the Admission Control (ACM) for this radio.
Procedure
Step 1 |
Choose to open the SIP Snooping page. |
Step 2 |
Specify the call-snooping ports by entering the starting port and the ending port. |
Step 3 |
Click Apply and then click Save Configuration. |
Configuring SIP-Based CAC (CLI)
Procedure
Step 1 |
Set the voice to the platinum QoS level by entering this command: config wlan qos wlan-id Platinum |
Step 2 |
Enable the call-snooping feature for a particular WLAN by entering this command: config wlan call-snoop enable wlan-id |
Step 3 |
Enable the ACM to this radio by entering this command: config {802.11a | 802.11b} cac {voice | video} acm enable |
Step 4 |
To configure the call snooping ports, enter this command: config advanced sip-snooping-ports starting-port ending-port |
Step 5 |
To troubleshoot SIP-based CAC events, enter this command: debug sip event {enable | disable} |
Voice Prioritization Using Preferred Call Numbers
You can configure a controller to support calls from clients that do not support TSPEC-based calls. This feature is known as voice prioritization. These calls are given priority over other clients utilizing the voice pool. Voice prioritization is available only for SIP-based calls and not for TSPEC-based calls. If the bandwidth is available, it takes the normal flow and allocates the bandwidth to those calls.
You can configure up to six preferred call numbers. When a call comes to one of the configured preferred numbers, the controller does not check on the maximum call limit. It invokes the CAC to allocate bandwidth for the preferred call. The bandwidth allocation is 85 percent of the entire bandwidth pool, not just from the maximum configured voice pool. The bandwidth allocation is the same even for roaming calls.
This section contains the following subsections:
Prerequisites for Configuring Voice Prioritization Using Preferred Call Numbers
You must configure the following before configuring voice prioritization:
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Set WLAN QoS to platinum.
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Enable ACM for the radio.
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Enable SIP call snooping on the WLAN.
Configuring a Preferred Call Number (GUI)
Procedure
Step 1 |
Set the WLAN QoS profile to Platinum. |
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Step 2 |
Enable ACM for the WLAN radio. |
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Step 3 |
Enable SIP call snooping for the WLAN. |
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Step 4 |
Choose Preferred Call page. to open theAll calls configured on the controller appear.
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Step 5 |
Click Add Number to add a new preferred call. |
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Step 6 |
In the Call Index text box, enter the index that you want to assign to the call. Valid values are from 1 through 6. |
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Step 7 |
In the Call Number text box, enter the number. |
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Step 8 |
Click Apply to add the new number. |
Configuring a Preferred Call Number (CLI)
Procedure
Step 1 |
Set the voice to the platinum QoS level by entering this command: config wlan qos wlan-id Platinum |
Step 2 |
Enable the ACM to this radio by entering this command: config {802.11a | 802.11b} cac {voice | video} acm enable |
Step 3 |
Enable the call-snooping feature for a particular WLAN by entering this command: config wlan call-snoop enable wlan-id |
Step 4 |
Add a new preferred call by entering this command: config advanced sip-preferred-call-no call_index {call_number | none} |
Step 5 |
Remove a preferred call by entering this command: config advanced sip-preferred-call-no call_index none |
Step 6 |
View the preferred call statistics by entering the following command: show ap stats {802.11{a | b} | wlan} ap_name |
Step 7 |
Enter the following command to list the preferred call numbers: show advanced sip-preferred-call-no |
Enhanced Distributed Channel Access Parameters
Enhanced Distributed Channel Access (EDCA) parameters are designed to provide preferential wireless channel access for voice, video, and other quality of service (QoS) traffic.
This section contains the following subsections:
Configuring EDCA Parameters (GUI)
Procedure
Step 1 |
Choose Wireless and then Network under 802.11a/n/ac or 802.11b/g/n, unselect the 802.11a (or 802.11b/g) Network Status check box, and click Apply to disable the radio network. |
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Step 2 |
Click EDCA Parameters under 802.11a/n/ac or 802.11b/g/n. |
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Step 3 |
The 802.11a (or 802.11b/g) > EDCA Parameters window is displayed. |
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Step 4 |
Choose one of the following options from the EDCA Profile drop-down list:
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Step 5 |
To enable MAC optimization for voice, check the Enable Low Latency MAC check box. By default, this check box is not checked. This feature enhances voice performance by controlling packet retransmits and appropriately aging out voice packets on lightweight access points, which improves the number of voice calls serviced per access point.
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Step 6 |
Click Apply to commit your changes. |
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Step 7 |
To re-enable the radio network, click Network under 802.11a/n/ac or 802.11b/g/n, check the 802.11a (or 802.11b/g) Network Status check box, and click Apply. |
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Step 8 |
Click Save Configuration. |
Configuring EDCA Parameters (CLI)
Procedure
Step 1 |
Disable the radio network by entering this command: config {802.11a | 802.11b} disable network |
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Step 2 |
Save your settings by entering this command: save config |
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Step 3 |
Enable a specific EDCA profile by entering this command: config advanced {802.11a | 802.11b} edca-parameters {wmm-default | svp-voice | optimized-voice | optimzed-voice-video | custom-voice |fastlane}
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Step 4 |
View the current status of MAC (low latency MAC) optimization for voice by entering this command: show {802.11a | 802.11b} Information that is similar to the following example is displayed:
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Step 5 |
Enable or disable MAC optimization for voice by entering this command: config advanced {802.11a | 802.11b} voice-mac-optimization {enable | disable}
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Step 6 |
Re-enable the radio network by entering this command: config {802.11a | 802.11b} enable network |
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Step 7 |
Save your settings by entering this command: save config . |
Key Telephone System-Based CAC
Key Telephone System-based CAC is a protocol that is used in NEC MH240 wireless IP telephones. You can configure the controller to support CAC on KTS-based SIP clients, to process bandwidth request message from such clients, to allocate the required bandwidth on the AP radio, and to handle other messages that are part of the protocol.
When a call is initiated, the KTS-based CAC client sends a Bandwidth Request message to which the controller responds with a Bandwidth Confirm message indicating whether the bandwidth is allocated or not. The call is allowed only if the bandwidth is available. If the client roams from one AP to another, the client sends another Bandwidth Request message to the controller.
Bandwidth allocation depends on the median time calculated using the data rate from the Bandwidth Request message and the packetization interval. For KTS-based CAC clients, the G.711 codec with 20 milliseconds as the packetization interval is used to compute the medium time.
The controller releases the bandwidth after it receives the bandwidth release message from the client. When the client roams to another AP, the controller releases the bandwidth on the previous AP and allocates bandwidth on the new AP, in both intracontroller and intercontroller roaming scenarios. The controller releases the bandwidth if the client is dissociated or if there is inactivity for 120 seconds. The controller does not inform the client when the bandwidth is released for the client due to inactivity or dissociation of the client.
This section contains the following subsections:
Restrictions for Key Telephone System-Based CAC
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The controller ignores the SSID Capability Check Request message from the clients.
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Preferred call is not supported for KTS CAC clients.
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Reason code 17 is not supported in intercontroller roaming scenarios.
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To make the KTS-based CAC feature functional, ensure that you do the following:
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Enable WMM on the WLAN
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Enable ACM at the radio level
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Enable processing of TSPEC inactivity timeout at the radio level
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All RLAN clients are disconnected when Call Admission Control (CAC) is enabled or disabled to apply policies.
Configuring KTS-based CAC (GUI)
Before you begin
To enable KTS-based CAC for a WLAN, ensure that you do the following:
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Set the QoS profile for the WLAN to Platinum.
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Set the WLAN in disabled state.
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Set the FlexConnect Local Switching in disabled state for the WLAN (On the WLANs > Edit page, click the Advanced tab and uncheck the FlexConnect Local Switching check box).
Procedure
Step 1 |
Choose WLANs to open the WLANs page. |
Step 2 |
Click the ID number of the WLAN for which you want to configure the KTS-based CAC policy. |
Step 3 |
On the WLANs > Edit page, click the Advanced tab. |
Step 4 |
Under Voice, check or uncheck the KTS based CAC Policy check box to enable or disable KTS-based CAC for the WLAN. |
Step 5 |
Save the configuration. |
Configuring KTS-based CAC (CLI)
Before you begin
To enable KTS-based CAC for a WLAN, ensure that you do the following:
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Configure the QoS profile for the WLAN to Platinum by entering the following command:
config wlan qos wlan-id platinum
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Disable the WLAN by entering the following command:
config wlan disable wlan-id
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Disable FlexConnect Local Switching for the WLAN by entering the following command:
config wlan flexconnect local-switching wlan-id disable
Procedure
Step 1 |
To enable KTS-based CAC for a WLAN, enter the following command: config wlan kts-cac enable wlan-id |
Step 2 |
To enable the functioning of the KTS-based CAC feature, ensure you do the following: |
Related Commands
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To see whether the client supports KTS-based CAC, enter the following command:
show client detail client-mac-address
Information similar to the following appears:
Client MAC Address............................... 00:60:b9:0d:ef:26 Client Username ................................. N/A AP MAC Address................................... 58:bc:27:93:79:90 QoS Level........................................ Platinum 802.1P Priority Tag.............................. disabled KTS CAC Capability............................... Yes WMM Support...................................... Enabled Power Save....................................... ON
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To troubleshoot issues with KTS-based CAC, enter the following command:
debug cac kts enable
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To troubleshoot other issues related to CAC, enter the following commands:
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debug cac event enable
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debug call-control all enable
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