Show and debug command to troubleshoot roaming

[Difan Zhao]

Hi experts,

I have complain that in some areas the voip phones sound choppy. I checked the signal strength in that area and it was actually too many APs with acceptable signal strength. I think it might be that the phone keeps roaming among the APs which caused the packets to drop. I am trying to prove it so they can get the phone vendor to change the roaming threshold. Is there debug and show command I can use to check for the roamin history of a client (with specific MAC address)? The debug client <MAC> doesn't show the roaming activity.

The controller is WISM2 running 7.2.110.0 code

Thanks,

[Scott Fella · Accepted solution]

If you had an MSE and WCS/NCS/PI, you could look at the roaming history. The debug client will show you real time roaming not roaming history.

Sent from Cisco Technical Support iPhone App

[Difan Zhao]

Thanks Scott! No I don't have WCS yet. I will have one but not for a while. The "debug client" doesn't show me roaming activity at all... I turned on the debut while the client roamed at least for 3 or 4 APs but I don't see any debug output. The "show client detail" clearly showed that the client has been moved to another AP... Is there not a debug command on the WLC to show the roaming activity?

thanks!

[Stephen Rodriguez · Accepted solution]

No there isn't a specific debug for roaming,

but debug client < client mac > should show you when it roams to a new AP.  What type of security is being used?

HTH,
Steve

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[Difan Zhao]

Thanks Stephen for your reply... It is as simple as WEP 104 bit preshared key. Somehow the debug client doesn't show anything about roaming, not even something like association/disassociation from an AP or something which could indicate a roaming activity.

Our roaming mostly happen between APs on the same controller. Sometimes it might go to different controller. When roamed to the different controller, the IP subnet for that WLAN remain the same. Is it l2 roam? I found debug command "debug l2roam xxx". The manual only differentiate roaming by intra-controller or inter-controller. It doesn't have anything about l2 roam...

Thanks,

[Scott Fella]

The debug client Mac will show the client associate and disassociate from an ap. that's how you would see the client roam. That is the command I use to troubleshoot or look at client roam issues.

Sent from Cisco Technical Support iPhone App

[George Stefanick]

Are these Cisco phones ? If so syslog the phone or web into it.

As for the controller side, client debug as Scott mentioned does the trick. If you don't see any client activity it's likely the client is on the other wlc ?

Sent from Cisco Technical Support iPhone App

[Difan Zhao]

No those are Vocera badges. I will ask them. Why is it 8 channels? They are only on 2.4GHz and APs are on 1,6 or 11. Can I ask them to set just on the three channels to speed up the roaming process?

[Difan Zhao]

Thanks George. no unfortunately those are not the Cisco phones... They are not evey phones. They are Vocera Badges. Their antennas must be even worse

[George Stefanick · Accepted solution]

Vocera badges eh ? I have a few hundred of these myself. A few questions and some things you need to be aware of.

If you have B1000s and if these are your issues dont troubleshoot them, just replace them.

if they are B2000,B3000 you need to make sure you have a tight wireless design to support vocera. I even call out Vocera as a "vocera grade" design. I would check the areas with the badge by putting the badge into site survey mode and make sure you have -65 or better. If you dont you need to fix that first. Also make sure your APs arent higher than 25 mW ..

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

[Difan Zhao]

Thanks George!

Those are B2000. I think we have installed too many APs... They are 3602 and they are like a few meters apart...

Most APs are at power level 7 (auto selected).

How do I check the power level? Is this "-65" the dbm? I have this inSSIDer software. It has a column called RSSI. Is this the field I should check? What's the 25mW? Is 25mW equvilent to 13dbM?

Thanks!

[George Stefanick]

If most of your APs are at 7 then I might agree, you have to many access points. But without seeing your design I dont want to comment.

Yes, -65 dBm. But it is very important dont use your laptop to see the signal strength. Rather use the badge itself and use it how the users are using it, around their neck. If they are holding it in their hand, thats a NO NO.

Remember each device hears differently. So if you used your laptop you might see a different dBm sginal than the badge consistently. Always use the device that is having issues.

The 3600 aps can transmist at the following 2.4 GHz levels ..

1 - 100mW <20 dBm>

2 - 50 mW <17 dBm>

3 - 25 mW <14 dBm>

4 - 12.5 mW <11 dBm>

5 - 6.25mW <8 dBm>

6 - 3.12 mW <5 dBm>

7 - 1.56 mW <2 dBm>

You can see if your APs are on 7 they are so low they must have a 10 feet foot print.

Do you have omnipeek or airmagnet to see channel utilization ?

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

[George Stefanick]

LOOK AT ME VIP ENDORSED .. lol

Who did it ? Leo ? Cant be Leo .. he hasnt rated a post since 1967 ..

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."

[Difan Zhao]

Thank you! I will contact Vocera regarding to how to check the RSSI on the badge.

I don't have Omnipeek or Airmagnet. However this inSSIDer that I have apparently does the same by showing me the channel utilization. I will check the utilization when I go back to the site. Last time I see a lot in the 1,6,11 channels with higher than -65 dbm...

The power strength mapping table you provided is very useful. Thanks for that!

[George Stefanick]

You put the badge into survey mode it will show you the dBm. If you speak to Jason over at Vocera Support tell him George said HI .. LOL

As for utilization. Unfortunately, inSSIDer will not show utilization. It will show how many aps and what signal. But not true util.   

Look at attached .. Look at number "1" .. Thats what I am referencing .. This tells me 65% of the channel is used.

      

__________________________________________________________________________________________
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
__________________________________________________________________________________________
‎"I'm in a serious relationship with my Wi-Fi. You could say we have a connection."