client wont connect to closest AP

[Babak KHorshid]

hi every one

this is the second post. the first one is missing!

long story short, client connection is random. doesnt connect to the closest AP.

i have situation like 40 clients connected to one AP and 2 meter away an AP only servicing 4 ! 

i have wlc 5508 and 100 AP. i tried aggressive load balancing and end up having more issue! tried restrict an AP to 25 but no use i can see some AP servicing 40 clients no matter what i define. i disabled the slow data rate nothing happened. i have none CCX clients but on few CCX client no difference and same result

is there anyone who can tell me how to force the client to connect to closest AP?

really frustrated , thanks for your comments. 

[Leo Laohoo]

The "final" decision to join which AP and/or which radio falls on the wireless client.  If the wireless client wants to associate to the furthest AP then there's nothing you can do. 

One way of minimizing this from happening is to ensure your wireless clients are running the latest drivers.   On the AP-side, you could also try to disable the low-speed data rates (from 11 Mbps and below, make 18 Mbps as Mandatory and the rest are Supported).   Do NOT enable Client Load Balancing.  

[Babak KHorshid]

Thanks Leo for the reply

i checked and actually they are using the latest driver. The thing which is killing me is the decsion is to stupid by the client to even consider! You wont believe one of my client has 6 AP around it and even one just 2 meter away but still rather to connect to the one which has RSSI of -87 and SNR of 18!!!

its just crazy that im thinking im doing somthing wrong

[Leo Laohoo · Accepted solution]

A few months ago, a vendor wanted to sell a robot to a health establishment (hospital).  The robot "steers" via wireless.  It operates with the elevator (modified, of course) to go to different floors.  All, of course, done using wireless.  Now, the issue we found is the OS is Ubuntu.  Next, we found that the people making the robot depended on ONE person:  The programer.  And it's a one-man-operation.   His knowledge about Ubuntu may be good but his knowledge to wireless is pretty ... ummmm ... "ok".   The problem facing this product is it cannot roam well.  

6 months of testing in this building yielded nothing until someone from our side trawled through the different Ubuntu config files (and there were a lot) and stumbled on a filename for Ubuntu which dictates how the drivers behave.  One of the settings is the MINIMUM signal value before the NIC card (Intel) decides to join to another AP.  The default value is set to -90 dBm.  Once this value was changed to -68 dBm things started to work.  

What I am saying is check the "application" that controls the wireless NIC.  There are settings for it to move aggressively if a stronger signal is detected.

On the WLC, make sure DCA and TPCv1 is enabled.

[Babak KHorshid]

HI Leo

Thanks. I think you are making a valid point. here we are a school and have multiple brand laptops. some of them has the aggressive mobility feature. some dont. I start to play with a test machine and see if it actually makes a difference

on the WLC the DCA is set to auti but the TPCv2 is enabled. I changed it to v1 and im going to test it now. I'll keep you posted as soon as the test finished.

at the moment it is what the client see:

      Number of Mic Failured Packets............. 0
      Number of Mic Missing Packets.............. 0
      Number of RA Packets Dropped............... 0
      Number of Policy Errors.................... 0
      Radio Signal Strength Indicator............ -52 dBm
      Signal to Noise Ratio...................... 46 dB
Client Rate Limiting Statistics:
      Number of Data Packets Recieved............ 0
      Number of Data Rx Packets Dropped.......... 0
      Number of Data Bytes Recieved.............. 0
      Number of Data Rx Bytes Dropped............ 0
      Number of Realtime Packets Recieved........ 0
      Number of Realtime Rx Packets Dropped...... 0
      Number of Realtime Bytes Recieved.......... 0
      Number of Realtime Rx Bytes Dropped........ 0

--More-- or (q)uit
      Number of Data Packets Sent................ 0
      Number of Data Tx Packets Dropped.......... 0
      Number of Data Bytes Sent.................. 0
      Number of Data Tx Bytes Dropped............ 0
      Number of Realtime Packets Sent............ 0
      Number of Realtime Tx Packets Dropped...... 0
      Number of Realtime Bytes Sent.............. 0
      Number of Realtime Tx Bytes Dropped........ 0
Nearby AP Statistics:
      VisualARTS_A(slot 0)
        antenna0: 34 secs ago.................... -88 dBm
        antenna1: 34 secs ago.................... -88 dBm
      Senior_DS2.4B(slot 0)
        antenna0: 34 secs ago.................... -90 dBm
        antenna1: 34 secs ago.................... -87 dBm
      Senior_DS2.8(slot 0)
        antenna0: 34 secs ago.................... -89 dBm
        antenna1: 34 secs ago.................... -85 dBm
      Senior_EnglishOff(slot 0)
        antenna0: 34 secs ago.................... -61 dBm
        antenna1: 34 secs ago.................... -54 dBm
      Senior_EnglishOff(slot 1)
        antenna0: 37 secs ago.................... -72 dBm

--More-- or (q)uit
        antenna1: 37 secs ago.................... -76 dBm
      Senior_DS2.7(slot 0)
        antenna0: 34 secs ago.................... -87 dBm
        antenna1: 34 secs ago.................... -80 dBm
      SeniorSchool(slot 0)
        antenna0: 34 secs ago.................... -82 dBm
        antenna1: 34 secs ago.................... -78 dBm
      Senior_DS1.6(slot 0)
        antenna0: 34 secs ago.................... -62 dBm
        antenna1: 34 secs ago.................... -67 dBm
      Senior_DS1.6(slot 1)
        antenna0: 37 secs ago.................... -68 dBm
        antenna1: 37 secs ago.................... -71 dBm
      Senior_DS1.2A(slot 0)
        antenna0: 34 secs ago.................... -34 dBm
        antenna1: 34 secs ago.................... -37 dBm
      Senior_DS1.2A(slot 1)
        antenna0: 37 secs ago.................... -32 dBm
        antenna1: 37 secs ago.................... -49 dBm
      Senior_DS2.4A(slot 0)
        antenna0: 34 secs ago.................... -87 dBm
        antenna1: 34 secs ago.................... -89 dBm
      Science_Indonesia(slot 0)

--More-- or (q)uit
        antenna0: 34 secs ago.................... -93 dBm
        antenna1: 34 secs ago.................... -89 dBm
      Senior_HeadOfHous(slot 0)
        antenna0: 34 secs ago.................... -73 dBm
        antenna1: 34 secs ago.................... -74 dBm
      Senior_DS2.2(slot 0)
        antenna0: 34 secs ago.................... -80 dBm
        antenna1: 34 secs ago.................... -80 dBm
      Senior_DS1.7(slot 0)
        antenna0: 34 secs ago.................... -59 dBm
        antenna1: 34 secs ago.................... -50 dBm
      Senior_DS1.7(slot 1)
        antenna0: 36 secs ago.................... -70 dBm
        antenna1: 36 secs ago.................... -74 dBm
      Senior_Students_R(slot 0)
        antenna0: 34 secs ago.................... -85 dBm
        antenna1: 34 secs ago.................... -83 dBm
      Senior_DS1.4(slot 0)
        antenna0: 34 secs ago.................... -60 dBm
        antenna1: 34 secs ago.................... -64 dBm
      Senior_DS1.4(slot 1)
        antenna0: 36 secs ago.................... -73 dBm
        antenna1: 36 secs ago.................... -74 dBm

--More-- or (q)uit
      Senior_DS1.2B(slot 0)
        antenna0: 34 secs ago.................... -57 dBm
        antenna1: 34 secs ago.................... -50 dBm
      Senior_DS1.2B(slot 1)
        antenna0: 37 secs ago.................... -53 dBm
        antenna1: 37 secs ago.................... -62 dBm
      Senior_DS1.5(slot 0)
        antenna0: 34 secs ago.................... -63 dBm
        antenna1: 34 secs ago.................... -65 dBm
      Senior_DS1.5(slot 1)
        antenna0: 36 secs ago.................... -79 dBm
        antenna1: 36 secs ago.................... -84 dBm
DNS Server details:

[Scott Fella]

TPCv1 should be used and not TPCv2. If your still running into issues, your better off starting clean and using as much as the default as possible. When you start changing some of the defaults and not stating what has changed, it becomes very hard to troubleshoot. We assume that most of the defaults are still in place and any changes would of been stated in the original post.  let us know if your test has better results. 

Scott

[Babak KHorshid]

After changing back to TPCv1 the connectivity improved much more. I haven't fully tested  but seems normal now. I can see some clients still acting wired and taking stupid decisions but in general it is at least the second best option they are connecting. I had drop out issue as well which seems to be fixed.

Because we are having a very noisy environment we changed it to TPCv2 and forgot about it! any way the slow rate are disabled too. 

thanks every one for the help and specially Leo for pointing out the TPCv1. I will post another update after some day which I monitor it. 

[Leo Laohoo]

Noooooooooooooooooooooo ... Do not use TPCv2.  Use TPCv1.  

You only use TPCv2 if you want to cut your hair but are too lazy to go to the barber.  

[Timohamoto]

Impressive explanation. I will memorize that story.