Controller Based WLANs

What are airgroup global credits and how does they prevent controller from getting unresponsive answering excessive mDNS queries?

Aruba Employee
Question What are global credits and how does they prevent controller from getting unresponsive answering excessive mDNS queries?
Environment This article applies to Aruba Mobility Controllers running ArubaOS version 6.3.0.0 and have Airgroup enabled.

 

 

In an AirGroup network, devices generate excess mDNS query/response packets and excessive mDNS packets can impact the performance of AirGroup controller. Using airgroup global-credits, controller limits the number of mDNS packets that are processed.

Controller assigns separate credit values to query and response packets.Credit is decremented by one, when a query or response packet is processed by controller. Any query/response packet will be dropped by controller when the corresponding credit is zero.
 
Credit values are renewed every 15 seconds and the renewal time is not a configurable parameter. Default global credits vary based on airgroup controller platform.

For example, below are the screenshots from 3200XM and 3400 Aruba mobility controllers:
rtaImage.jpg
 
rtaImage2.jpg
 
The above command also shows current credit value that show how many query/responses have been processed by controller after last renewal. 

Based on the load on the controller, one can increase the number of mDNS query/responses that a controller can process in a interval of 15 seconds. Use the command:

 "airgroup global-credits <query-packets> <response packets>"
 
rtaImage3.jpg
 
NOTE: Because of the limitation of number of mDNS queries processed per 15 seoonds, in some large networks user may experience some delay in discovering the servers. This is normal and been designed to stop controller from going unresponsive.

 

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Last update:
‎07-11-2014 02:41 PM
 
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