SIMS/Outlook freezing/not responding over Meru wireless

[profit10]

Hi,

 

We are having a problem with a few users using SIMS and Outlook when using wireless. It doesn't affect everyone, even for some users in the same room connected to the same AP. It only happens on wireless, if the problem user is wired then all is fine.

 

A user can be connected and using SIMS/Outlook and then it will randomly freeze and display Not Responding for 30-60 seconds before returning to normal. This can happen several times a day. The wireless doesn't actually drop at the time of the freeze.

 

I've checked the event logs at these times and there are no errors or anything that seem to be of help.

All drivers are up to date.

It happens with both 2.4 and 5ghz wireless cards.

 

Any help with this would be great,

 

Thanks.

[TheRobins]

I've had similar issues recently.

 

Now out of interest, are they intel chipsets in the wireless.

 

I have got loads of information and diags, but you would need putty and root access to controller

[profit10]

They are indeed Intel chipsets.

 

I can get hold of putty and get access.

[TheRobins]

Out of interest which chips, Am I guessing Centrino?

[profit10]

They are Intel 7260s.

 

Have you resolved your issues?

[Oaktech]

Have a check in the settings for the cards and see if checksum offloading is enabled or disabled for the cards. Whichever setting it's on - try the other one!

[TheRobins]

Yes, Fixed my issues with the 7260's, I have a room of 30 lenovos as we speak all using 7260's on the same ap no issues. This issue is related to "roaming aggressiveness"

 

What happens is the control really wants to be in control of any hand-offs or AP assignments. The Intel range of cards ignore this and in the background will go searching for new ap's. Of course the single channel setup causes confusion and it cause the card to try and access an AP that will not respond.

 

A quick test is

 

Login into an SSH session the running the following. Station log > enable

 

Meru-Controller(15)#
Meru-Controller(15)#
Meru-Controller(15)# station-log
Interactive Per-Station Event Logging Shell (enter "help" for help)
By default logging is Disabled (enter "enable" to Enable logging)
station-log> enable
Logging enabled
station-log>

 

What you will see is the devices on your network as the communicate with the controller and as it hands it around ap's similar to below

 

2015-May- 7 13:37:11.677882 | e8:de:27:1d:68:c7 | 802.11 State           |  handoff  RSSI (-65 -66)  RSSI (-61 -62) 
2015-May- 7 13:37:17.682556 | e8:de:27:1d:68:c7 | 802.11 State           |  handoff  RSSI (-66 -61)  RSSI (-59 -59) 
2015-May- 7 13:38:08.279700 | 20:68:9d:e0:61:03 | Station Assign         |  assigned to 
2015-May- 7 13:38:08.280160 | 20:68:9d:e0:61:03 | Station Assign         | Reassigning from (rssi=-75) to (rssi=-39) 
2015-May- 7 13:38:08.280164 | 20:68:9d:e0:61:03 | Station Assign         |  Assign Removed From 
2015-May- 7 13:38:08.280319 | 20:68:9d:e0:61:03 | Station Assign         |  assigned to 
2015-May- 7 13:39:20.781974 | 80:19:34:a4:c8:8d | 802.11 State           |  handoff  RSSI (-80 -76)  RSSI (-74 -75) 

 

 

You can see that as the signal of a device gets weaker, it will switch it to the new AP and report the signal strength back. Usually the numbers are very close as the system tries to balance the load, or as people move laptops, even walk in front of a laptop can give 10-20 Db of attenuation.

With the intel roaming aggressiveness I expect you to be seeing some -256 ie RSSI (-70 -256) or (-256 -256)

 

Do check this first, if you start seeing -256 its more than likely to be the issue.

[profit10]

Thanks, I will give this a test.

 

If this is the issue, What is the fix? I know you say it is related to roaming aggressiveness, but how was it resolved?

[TheRobins]

This is where it got complex.

 

You can go to every intel AC7260 machine, log in, go to the advanced driver properties and change these to 1.lowest

 

 

There is a registry entry you can push via GPO, however sadly intel drivers dont always appear to be in exactly the same place, even with a batch of machines all imaged at the same time so its pot luck.

 

You could maybe test this if you are getting the -256 hits in the station logs. If this doesn't solve the issue you can do some tweaks to the ESS profiles as well as deeper into the controllers config for signal strength handoff's. I would at this point suggest registering this issue with Meru Support, as any changes from this point can cause issues down the line.

 

If turning the aggressiveness down to 1 solves it you should be ok.

 

I actually don't need to turn my aggressiveness down now, I have the latest firmware suggested by meru support which is 6.1-2-29, coupled with tweaks to the handling config it runs much better. I was also told that V7 which is out soon is far superior especially with Intel, but we would all say that wouldn't we. We are using the MC1550 Controller and 25 AP832E access points.