Controller Based WLANs

ARM Load Aware Scan ? how it works and configuration

ARM ‘load aware scan’ enables APs to reject ARM scans during periods of high traffic.

AP keeps track of transmitted and received data in bytes between two scan requests. It uses this information to calculate bytes per second. Control and management traffic is not taken into consideration during these calculations.

On receiving scan request AP will compare its traffic load with configured threshold and if traffic is higher than threshold it will not scan.

Configuration;
•     It is configurable option in ARM profile – ‘load-aware-scan-threshold’
•     Default = 1250000 Bps which is 10 Mbps
(SDM3) #configure t
(SDM3) (config) #rf arm-profile default
(SDM3) (Adaptive Radio Management (ARM) profile "default") #load-aware-scan-threshold <load-aware-scan-threshold in bytes per sec>
Range: 0-160Mbps
Default: 1.25 MBytes per sec (10 Mbps) Use 0 to disable this feature

Show Commands;

1. to verify configuration;

(wl2h-L) #show rf arm-profile default

Adaptive Radio Management (ARM) profile "default"
-------------------------------------------------
Parameter                         Value
---------                         -----
Assignment                        single-band
Allowed bands for 40MHz channels  a-only
Client Aware                      Enabled
Max Tx Power                      30 dBm
Min Tx Power                      21 dBm
Multi Band Scan                   Enabled
Rogue AP Aware                    Disabled
Scan Interval                     10 sec
Active Scan                       Disabled
Scanning                          Enabled
Scan Time                         110 msec
Power Save Aware Scan             Enabled
Ideal Coverage Index              10
Acceptable Coverage Index         4
Free Channel Index                25
Backoff Time                      240 sec
Error Rate Threshold              50 %
Error Rate Wait Time              30 sec
Noise Threshold                   75 -dBm
Noise Wait Time                   120 sec         
Minimum Scan Time                 8 sec
Load aware Scan Threshold         1250000 Bps  <- configured threshold for load-aware-scan
Mode Aware Arm                    Disabled

2. Use below command to verify number of scans rejected because of high traffic load

(SDM3) #show ap debug radio-stats ap-name sd-125-fa:f0 radio 0 advanced | include Scan

Scan Requests             39
Scan Rejects              0
Load aware Scan Rejects   0 <- number of scan rejected because of load
PS aware Scan Rejects     0
Voice aware Scan Rejects  0
Scan Success              39
ARM Scan Frames           1031

* radio 0 = a and 1 = b/g

Version history
Revision #:
1 of 1
Last update:
‎07-06-2014 09:48 PM
Updated by:
 
Labels (1)
Contributors
Search Airheads
Showing results for 
Search instead for 
Did you mean: 
Is this a frequent problem?

Request an official Aruba knowledge base article to be written by our experts.