Wireless Access

So we have a 3200 XM controller with 500+ users on multiple SSID's all on the same VLAN. There is also Apple TV's in this enviroment. We are running Ap105 and AP125's

 

IN this case when multiple laptops in the same room (30 or so) connect to one of our ap125's the users will expierience drop off for a few minutes where they cannot do anything besides wait to reconnect. They are just using google drive and a few other apps. During this time we can see clients drop to 0 on both bands and interference go up on the 2.4 band. Here are a few screens.

 

http://i.imgur.com/xzd2lJ5.jpg

http://i.imgur.com/91zPCjc.jpg

 

We have one AM up in that exact area and there is only one other AP around and its running 2.4 on channel 1. Our AP's are on 6 most of the time.

 

Can someone give me an Idea of what I need to do to start diagnosing this? Thanks.

#3200

1.  Your channel utilization is too high on 2.4ghz.  What is the power on that access point and how many access points can be seen from within that room

2.  How many SSIDs are you broadcasting? That can increase channel utilization significantly.  Why do you have multiple SSIDs if your users just end up on the same VLAN?

3.  Do you have drop broadcast and multicast enabed on all ofyour virtual APs?

4.  What version of ArubaOS are you running?

You can only see the one access point from this room, sometimes the one in the floor above will pop up but it is a very very weak signal and usually a computer wont even be able to connect to it. 

 

We are broadcasting multiple SSID's because we have one Guest SSID (which actually is on a seperate VLAN)  Also one staff and one student that go to the same VLAN. The only reason we have this setup is because students have figured out WPA keys in the past and it was alot easier to just change one SSID's key and the computers associated with it rather than all students and staff. Keep in mind there are our computers being used on the student network also.

 

So total we have 4 SSID's being broadcast. I should also mention we have multiple AP's with this same profile and no issues.

 

Drop broadcast and multicast is not turned off. What functionality would I use if this was the case?

 

Aruba OS:  6.1.3.11

Okay.  Since you have a very large layer2 broadcast domain, dropping broadcast and multicast on the Virtual AP will stop alot of that traffic and improve performance.  You would need to do it on all virtual APs (4) in that AP group.

 

You will lose the ability to discover or connect to bonjour devices.

 

I cant drop broadcast on that domain for the apple TV reason. And Im not able to create a seperate VLAN for the Apple TV's and iPads because they need to be on our regular network because of the way our ISP filters (they need access to YouTube on the Apple devices) Do you have any other suggestions?

How many Apple TVs do you have and what do you use them for?

You can decrease utilization by only using a single SSID, instead of one for student and 1 for teachers.  The Radius server could check the AD group of the user and then send back and attribute based on what VLAN the user should be on.

At minimum, you can drop broadcast and multicast on the GUEST VLAN.

You can remove the lower rates on each SSID to reduce utilization

Are you using band steering to move 5ghz-capable devices to the 5ghz band?

Last but not least - ArubaOS 6.3 and above have Airgroup which would allow you to deploy bonjour, but still enable drop broadcast and multicast.

There is only 5 Apple TV's in the building we are talking about, they are used for teachers to show videos to the classroom through airplay and also to display what they are doing on thier screens while using an instructional app.

 

I have not looked into radius yet, and would need to do some research to implement that.

 

Im going to drop broadcast on the Guest right now.

 

What do you mean by lower rates on each SSID? beacon rates?

 

Band steering is not turned on, I will turn that on now also.

 

 

Are you using a preshared key for students and a preshared key for teachers, and a third SSID that is also preshared, then?

 

EDIT:  A thread on removing lower rates is here:  http://community.arubanetworks.com/t5/Unified-Wired-Wireless-Access/2-4GHz-Unusable/m-p/69256/highlight/true#M2306

 

Yes WPA2-PSK..

So you have 3 PSK networks and one guest network?  Is that to separate them for the web filter?

 

EDIT:  The calculator here:  https://www.dropbox.com/s/imjrugrpyyscd75/Wi-Fi%20SSID%20Overhead%20Calculator.xlsx shows you how much overhead is generated by each SSID that you add...

 

What version of Aruba OS are you on? If its possible for you to upgrade to 6.3.x , being able to use Airgroup and turn on Drop Broadcast/Multicast would definitely help. You could also turn on Client Match which among other things would assist getting 5 Ghz capable clients on that. I'd also consider what your min and max power settings are. Typically 12 min and 18 max will cover many scenarios and ensure your clients aren't connecting to less than ideal APs.