Wireless Access

Occasional Contributor II

wireless network contention

How can I, with an Aruba controller-based network, quantify or measure the level of contention in that network?


We have a customer with a 650 controller and 7 APs. They are running HP slate tablets and an application that is EXTREMELY chatty, with nearly a 5 to 1 ratio of broadcast to unicast traffic. I think the total bandwidth in use is very low, but there is such a huge number of broadcast packets, that I suspect problems are encounterd due to contention. 


The symptoms are that when they are running <18 tablets, things seem to work fine, but all tablets and 6 or so wired devices all broadcast their status and other infortmation every second or so. when they grow to 20+ devices the network starts to breakdown, by which I mean the tablets do not receive these broadcast pacekts in a timely fashion and go into a recovery mode.


Currently, the most tablets are 2.4 Ghz only and the few that support 11a do not seem to roam properly due to a driver issue. Furthermore, there is significant interference from microwaves on Ch11 -- enough that we had to disable that channel.


I am not really sure this is the issue, but it seems plausible, since the breakdown is directly proportional to the number of tablets on the network. We seemed to have made things better by running a filter on the uplink port on the controller, dropping broadcast frames from all but the manadatory devices on the wired network. This has improved the situation, but not totally solved it. 


I personally think the issue is all software and drivers, but what we are trying to do is use all the features we can with Aruba to mitigate the problem as much as possible.


So again, I am hoping for some ideas on what commands to try to take measurements of the level of contention, or the number of times a packet is attempted to be sent and has to wait for a clear moment, etc.


any ideas? Thanks much in advance.

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