Wireless Access

We use three SSID's in our school district. One is for Apple devices that teachers need broadcasting enabled for AirServer, another is for district provisioned laptops and the other is an open guest ssid for BYOD and chromebooks. Since upgrading to ArubaOS 6.4.2.14, we occassionally have issues where users can't connect to the open guest ssid. The secure ssid's with WPA2 keys still allow users to connect. As soon as I reboot the AP, it will begin accepting users on the Guest ssid again. Last week, I updated our controller to ArubaOS 6.4.3.6 in hopes that this would resolve the problem, but we had a few calls this morning from staff had students unable to connect to the open guest ssid. Rebooting the AP had them up and going in a few minutes.

I had read where some people were able to resolve the issue by disabling client match. Even with client match disabled, the issue still seems to occur every week or two on our open guest ssid. When one does it, it seems they all eventually do it so I just go head and reboot every AP after school gets out for the day.

We are running AP-105's and a 3600 controller.

Do you have large, flat subnets?

Do you have broadcast filtering enabled on all of your virtual APs?

You could have congestion on your networks due to broadcast propagation.  When you reboot the APs, the clients go away and this effect is lessened....Maybe..

The guest subnet is large. It's configured as 10.0.48.0 /20. The "Drop Broadcast and Unknown Multicast" and "Convert Broadcast ARP to Unicast" options are enabled for the Guest virtual AP profile.

We've ran this setup for many years and never experienced the issues until the upgrade to 6.4.2.12. I don't recall exactly which version of ArubaOS we had before, but it was old enough that we had to upgrade before we could begin using the AP-205's. The number of devices that are consistently connected to the Guest ssid has gone up substantially as well over the past year or two.

Do you have "Drop Broadcast and Multicast" on ALL of your Virtual APs?  Broadcast traffic, if not suppressed is something that can cause issues randomly, and not always when you are monitoring it.  If you do not have it on all of your Virtual APs,  I would try enabling it and see if it still continues to happen.  In addition, you should look at the Dashboard under Performance> Aps> Channel Busy to see if you have high utilization which can also be very random.  Upgrading or downgrading would not necessarily eliminate issues, because they occur randomly.

The other two SSID's do allow broadcast traffic, but they are on different subnets than our Guest ssid. They are actually setup as bridged connections and run on the same subnet as the wired devices. This is so that teachers can use AirServer to display their Ipad screens on their wired desktops in their classroom and also so that teachers with laptop carts can view the laptop screens that students are using with monitoring software from their wired desktops.

I watched the channel busy (%) for a while and everything has been in the green with the nearly all staying in the 0-10 range on the very far left. As the day goes on, I will continue checking it at different periods to see if that changes.

They all broadcast and receive traffic on the same channel.  Two devices, regardless of VLAN cannot talk at the same time on the same band.  When there is high utilization on your other WLANs, they will take airtime from your guest WLANs.  Suppressing broadcasts is a way to reduce unusable, but damaging overhead.  You said your LANs are bridged, so I am  not sure what kind of connectivity you have configured.  Typically if you want Airprint to work on a Tunneled SSID, you (1) turn on Airgroup and (2) Drop Broadcasts and Unknown multicast.  Airgroup would allow you to (1) Turn on Broadcast Suppression and (2) Have devices connect to Airprint and Airplay devices that are on different subnets.

Running wired and wireless clients on the same VLAN exposes the wireless clients to broadcasts from wired clients, which can seriously degrade the wireless traffic.  Is there any reason why your WLAN is bridged, besides for Airprint?

I guess I could setup AirGroup to handle the AirPlay traffic for the "Apple" ssid. The SSID that the laptops are on still needs to be on the same subnet as our wired devices for those buildings so that the wired desktops can view the laptop screens via the monitoring software. Disabling broadcasting on that SSID breaks the function of the software.

Is there a way to configure AirGroup to handle the broadcast traffic for this program? From what I remember, AirGroup had preconfigured options for certain things such as Chromecast and Apple AirPlay.

One more question, if it is a channel issue, shouldn't all of the SSID's be affected instead of just one? When the open Guest ssid stop's allowing a device to connect, I can enter the PSK for one of the other two SSID's and it will connect just fine to the same AP that it is trying to connect to on the guest ssid.

So, you should probably open a TAC case in parallel.  Wireless is a medium where multiple things can contribute to an issue and it does not get solved unless they are all dealt with.  You have alot of things going on, so you should engage TAC so you can get help to deal with your issues in specific.

We can still answer your questions here, but we might not know enough, without seeing your tech support and a diagram of your environment, what is really wrong....

what software is used to view laptops from desktops?

Airgroup handles the multicast DNS and DLNA traffic that are broadcasts typically.  It can turn them instead to unicasts.  If it is an RF issue, theoretically all devices on that access point would stop working, but that does not mean bad RF and unfiltered broadcasts is not contributing to the issue that you are currently seeing...

The program is called Smart Synchroneyes. My boss aid that we actually only have one room with laptops that are still using the program. Everybody else has Chromebooks in their classrooms now. I'll try disabling broadcasting for the other two SSID's and setting up AirGroup for use with the teacher Ipads and see if things improve. If not, I'll open up a TAC and see where things go from there. Thanks for the help.

Please PM me the logs.tar tech support from you controller so I can ask you some better questions...

Did you ever resolve this issue?  I seem to be having a very similar issue with a 7905 controller running 325s. 

This is what I ended up doing to fix it. I'm not sure if it was just one of these or a combination.

1. Change Local Probe Request Threshold from 25 to 0.
2. Enabled "Drop broadcast and multicast" and "Convert broadcast arp to unicast"
3. Configured AirGroup to handle broadcast needs.

Things have been working fine every since making these changes.