Wireless Access

I am not sure what is going on. Users are complaining that the application they are using freezes and a message of lost connection pops up. The clients that lose the connection are thin Wyse clients (C90LEW).  They do not lose connections all at once. There are 2 laptops in the same area without an issues.

 

We are running 6.3.1.2 with Client Match enabled. I have Airwave and have looked under the diagnostics. It shows from the client through the network as good.

 

I need to find out why it is just this one area. I have taken a taken running Aruba Utilities and other tools to check the signal. The signal does not fall below -60dbm. We have the Wyse clients in other areas and they have no issue. The other areas connection speeds for these clients are about 58-72Mbps in the area that is having the issue is 26-54Mbps.

Are those Wyse terminals 2.4ghz only?  In airwave, on one access point in the area, click on the 80211bgn radio and see what the noise, Channel utilization, and Goodput are and compare it to other access points in other areas during work hours...

I check several APs through the "house" and in the troubled area. The channels in the troubled area for bgn is 1,6,11. The noise level is -92/-93. The goodput does not show I looked back it seems to have stopped after upgrading to 6.3.1.2 ( I will have to look at this). The noise level is the same as in other areas that are working with now complaints.

 

The clinets in the troubled area, I have had DHCP assign the IP and I have statically assigned the IP. I have tried 2 different SSIDs, one open and one WPA2.

It only happens on the 2.4 channels. I have worked with TAC. They found everything in normal ranges. I even asked the SE about it. He had me run a few commands to check fame retries, channel noise and client SNR. He said everything looks fine.  We swapped out the Wyse clients with laptops that can handle the 5GHz channels. They said it is better but still seems slow. I have taken an extra AP-125 and put it as an air monitor to see if they is anything interfering with the clients. Any other ideas?

 

Can the AP-125 and M3 do spectrum analyzsis?

No they cannot. What is the channel utilization on the 2.4 GHz band for that access point?
Are you using drop broadcast and multicast on all of your virtual APS?
How many SSIDs are you broadcasting?

Channel Utilization= 12

I am not using drop broadcast and multicast. I was not sure how that would affect DHCP broadcast.

We have 4 SSIDs.

More SSIDs = More contention https://www.dropbox.com/s/imjrugrpyyscd75/Wi-Fi%20SSID%20Overhead%20Calculator.xlsx

 

Not dropping broadcast and multicast on every Virtual AP = more contention due to all broadcasts being propagated to all clients.  That single client that sends out a broadcast for UPNP?  It gets re-sent out of every access point that has a client on that VLAN, just like your wired network.  Unfortunately, wireless is shared, so every client that is on every access point that sees that broadcast has to pause before sending their traffic.  Multiply that by every broadcast a client sends X all of your APs that it has to be broadcast out of and it is a drag on your throughput.  Dropping broadcast and multicast enabled on the Virtual AP level permits DHCP and ARP.  It is not the default, but it is the second thing that we would turn on to troubleshoot a performance issue.

Thanks CJospeh for the Excel spreadsheet for calculating overhead. So for troubleshooting purposes you suggest dropping broadcast and multicast in all the virtual AP. Will the APs need to reboot  for the configuration to take affect?

No reboot necessary.  

 

In the AP-Group that those access points are in, go to every Virtual AP and enable "drop broadcast and multicast"  (make sure Convert Broadcast ARP requests to unicast is also enabled).

 

This is not to say that is your main or only issue, but in wireless, since the medium is shared, it could be a number of things that could be your problem and dropping broadcast and multicast in your Virtual AP profile will get some traffic off of that shared medium.

 

Also, make sure that the transmit power on your access points is between 12 and 18 in that area on both bands.

I will try it and post the results. Thanks again.