What is Virtual RF neighbor in Aruba Instant? How is it identified? what commands can be used to verify?

Aruba Employee

Environment : This article applies to all Aruba Instant Access Points running Aruba InstantOS 6.2.1.0-3.3.0.0 or higher.

 

 

Balancing spectrum utilization rather than number of clients per AP reduces co-channel interference and increases performance. Hence spectrum load balancing is based on the concept of creating virtual RF neighborhoods among access points for efficient client association management.

 

 

Spectrum Load Balancing (SLB) divides APs in a cluster into several logical virtual RF neighborhood domains and these AP's in the same RF neighborhood share the same clients. For example, in the below figure, there are 15 Instant APs in a cluster. Take AP1, AP2 and AP3, each of them has a different virtual RF neighborhood

rtaImage.jpg

  • The virtual RF neighborhoods are automatically created via ARM scanning, client density updates and neighbor exchanges.

 

  • This ensures that APs that are far away from the clients perspective do not belong to the virtual RF neighborhood, to avoid redirecting clients to a far away AP that is on a lightly loaded channel.

 

  • APs in the virtual RF neighborhood participate in client load balancing using association responses to direct clients towards APs on less loaded channels.

 

  • IAP's send updates which includes density map, working channel, and current associated clients count in that radio (sum of all vaps) in the form of Information Element (IE) within the probe request packets. Once the AP receives the update, it lists all the density maps in the database, and compare to my own density map. If the two density maps are 75%+ match, (which is controlled by "SLB Matching Interval" configuration parameter)  the neighbor is in my virtual RF neighborhood.

 

  • APs continously monitor the client associations and client count threshold on its own channel and if it hits condition (Current_associated >= Client_Threshold), load enforcement kicks in and clients starts associating to channels of other APs that have less client count. 
     
show ap debug spectrum-load-balancing <x>"  helps us to understand the RF neighborhood. 

(Where, x stands for radio: 0 or 1.  0 is for 5.GHz and 1 is for 2.4GHz)
 

 

IAP# show ap debug spectrum-load-balancing 0
 

 

Spectrum Load Balancing Status: RUNNING, Associated:1, Threshold:5   ===> Client Count Threshold

 

 

 

Spectrum Load Balancing Neighbor Table

 

--------------------------------------------

 

MAC                     Channel   Client_Count   Flags        Recved_Seconds

 

---                             -------     ------------      -----          --------------

 

00:24:6c:07:b2:60  48             0                     VR               85

 

00:24:6c:24:24:50  165           3                     VR               136

 

00:24:6c:33:06:00  165           9                     V                  281

 

00:24:6c:24:17:60  161           0                                         2180

 

00:24:6c:07:7e:80  36             0                     S                  296

 

 

 

Neighbor Flags: V - Valid; R - Is in Virtual RF Neighborhood; S - Same Channel

 

  • AP's with "VR" flag, are valid and in the same RF Neighborhood domain.
  • Whereas, AP's with "V" flag are valid but not in the same RF domain as the Instant AP that we are running the command on.
  • APs with "S" flag, indicates that they are on the same channel.
  • "Recved_Seconds" is the amount of the seconds before the update was received from neighbor AP of same RF neighborhood.
Note: The entry in the SLB neighbor table is aged out, if no entry from the neighbor AP is received in 5 mins (or) 300 seconds. 
 

 

 

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Last update:
‎06-27-2014 05:22 PM
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