Controllerless Networks

Group.......

 

I'm wondering if anyone has experienced issues with Ubuntu 14.04 and IAP115s.  We are a school district with a dense deployment of APs (essentially 1 per classroom).  Using Ubuntu 14.04, we have hit-and-miss connectivity and frequent disconnects.  We also see clients bypassing APs in the same room to try and connect to an AP 2 rooms away.

We have seen this with a number of different laptop models and a variety of network cards (both ABG and N capable Intel NICs).  We do not see the issue with Ubuntu 12.04, nor (in early testing) with Arch Linux (current versions).  The SSIDs are WPA2, though we've also seen the same sort of problems testing with open SSIDs.

We've been working with TAC on the issue for several weeks, but seem to be slowing on progress....we are now down to trying to do packet captures on failed connections, but are running into challenges as it is very hard to know where the client will connect.  We've tried limiting those options by reducing to only 2 WAPs (issue doesn't seem to occur with a single WAP), but the fewer the WAPs in the area, the more infrequent the issue.

I'm happy to provide details on the various network network cards, kernel versions tested, etc.  I just figured I'd see if anyone has tried dealing with Ubuntu and IAP 115s in any sort of dense deployment.

 

Thanks for any suggestions.

Hello,

 

I've received somewhat similar reports with a few Ubuntu users in a pilot group we have setup to test ClearPass.

 

In our scenario, our test network comprises of AP-225 and the user is running Ubuntu 14.04.  So a bit different from your setup of running IAPs.

 

The issue our Ubuntu user is facing is that the laptop in use gets punted between two AP's.  When the user is connected/associated to AP#1 he is on the 5GHz frequency and when connected/associated to AP#2 he is on the 2.4GHz frequency.  I'm sure ClientMatch is working it's magic of moving the user between the two APs but it seems to be occuring quite a few times during the day.

 

I have a TAC case open and waiting on reply back from TAC.  I've also let my SE know about the issue as our population of Ubuntu users is growing.

jasonmatthew1,

 

What is the Min and Max power for your access points?

 

In our most recent testing, client match seems to be the root of our issue.  Some of the clients (hit and miss) running a variety of cards, kernels, even Ubuntu-based variants were failing on the connection process or were being moved and failing to successfully get through the authentication phase (even when no security was specified).  Turning off client match seemed to clear up the initial connection challenges in our test environment and we'll be doing further testing in the next few weeks.  We were able to successfully create and then resolve connection issues as we toggled client match off and on.

 

 

drh,

 

I know you mentioned in your original post that clients would bypass an access point to connect to another further away.  What was/is the maximum power on your access points?

 

 

 

We have tried a number of settings, even going as low as a min transmit
power of 6 in our most dense areas. Even that didn't really fix things.
Units still connected to APs that were further away. Working with Aruba,
we now have our transmit power returned to Min: 18 Max: Max and are letting
ARM handle that side of things. When that seemed to result in very heavy
utilization in the 2.4 GHz ranges, we moved the min 2.4 GHz transmit rate
to 18 which resolved that issue.

Current hope is that Aruba will be able to work out some of the client
match settings so we can turn it back on and have the match benefits while
still being able to consistently have our Ubuntu clients connecting.

drh,

 

That is surprising.  Normally having the power over 18 causes more roaming issues.  We would normally start out at min 12 and max 18 to match the power of the clients that are transmitting.  I am very surprised that your minimum is 18 and your max is the max, which would cause the issue that you are trying to solve.

 

DRH,

  Were you able to find a reliable solution to this? We experience quite a few disconnects and random 'long-distance' AP connections on our Ubuntu machines. I know that the Ubuntu nic drivers have a hard time with roaming in general, though.