WM3600. WLAN Enforce Client Load Balancing

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Could somebody tell me how does it work? Does AP send to STA association reject with code 17?



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Roman

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Posted 3 years ago

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Bill Stritzinger, Alum

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We would suggest you not enforce client load balancing in WiNG, what version are you using?  In many environments we have had issues when turning on this feature. For more information please call TAC or give me more specifics and I can elaborate.
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Roman

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Bill,
Thank you for your comment. I use WM3600 version 5.4.2.0-031R. Really I was faced with issues when I switched on this feature. I would want to understand how it works.

Roman
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Chad Smith, Alum

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Roman,

There are two types of Load balancing: AP load balancing and Band load balancing.  

Band load balancing, sometimes referred to as "band steering" in the industry, attempts to move clients from a 2.4 GHz radio to a 5 GHz radio on the same device.  AP Load balancing attempts to distribute clients evenly across multiple APs in the same physical space.  This is intended for high density environments like auditoriums, etc.  I believe you are referring to AP load balancing so I will focus on this in the post.

Both load balancing features work by ignoring probe requests on the undesired device (or radio in the case of band load balancing).  So for example, in an AP load balancing scenario, if there were two APs in the same area and one AP is heavily loaded,  that AP would ignore probe requests sent by new clients.  Although the client could potentially still see beacons sent by the AP, this essentially makes this AP unavailable to that client and it will look elsewhere.  Meanwhile, the other AP in the area would respond normally to the probe requests and the client would connect.  The thresholds for how long to ignore probe requests and client loads are all user configurable.  You can view the customization options in the AP profile configuration under Advanced -> Client Load Balancing.

The challenge with AP load balancing is the infrastructure has to be aware of what APs are in the same physical space.  If this data is incorrect, load balancing will not work correctly. Both APs MUST be able to adequately service any client that will be shared amongst them.  If not, the client may see poor performance or even not be able to connect to the network.  

The most certain way to implement this is to manually configure a "load-balancing group-id" for APs within a certain area.  This tells the wireless infrastructure that these APs are in the same area and can share clients.  Other "automatic" neighbor selection techniques are also available (although I believe in a newer software release).  While the automatic neighbor selection may work well in some environments, it may not be perfect in others.  Manual configuration (buy a human) is always best.

When configuring AP load balancing please keep the following things in mind:
  • The AP needs to be enabled for load balancing with the command "load-balancing balance-ap-loads" in either the device configuration or the AP device profile.
  • The WLAN needs to be load balancing enabled with the command "client-load-balancing"
  • The "load-balancing group-id" must be defined, or some other neighbor selection strategy enabled in the AP device configuration.  If not, APs will not understand who to load share with.
  • Be careful when customizing load balance settings as you can set the parameters too strict or too loose, leading to poor performance and problems.  I would start with the defaults.