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Force channel change on LAP

Hi,

I have 3xLAP1242 in a building that are some what close to eachother (WCS show them as Rx Neighbors). The problem is that they are all running the same channel, 1 on 2.4GHz and channel 140 on 5GHz.

I guess that is why we see this in the log:

'802.11b/g' interface of AP 'AP001' associated to controller 'WiSM2' is up. Reason: Rogue Location Discovery Protocol stop.

'802.11b/g' interface of AP 'AP001' associated to controller 'WiSM2' is down. Reason: Rogue Location Discovery Protocol stop.            

and on the controller:

*Aug 28 07:46:15.931: %LWAPP-5-RLDP: RLDP stopped on slot 0.

*Aug 28 07:46:15.933: %LINK-3-UPDOWN: Interface Dot11Radio0, changed state to down

*Aug 28 07:46:15.950: %LINK-5-CHANGED: Interface Dot11Radio0, changed state to reset

*Aug 28 07:46:15.979: %LINK-3-UPDOWN: Interface Dot11Radio0, changed state to up

*Aug 28 07:50:58.113: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf

*Aug 28 07:59:45.902: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1

*Aug 28 08:06:02.441: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf

*Aug 28 08:14:51.177: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1

*Aug 28 08:21:09.764: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf

*Aug 28 08:29:54.463: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1

*Aug 28 07:46:15.931: %LWAPP-5-RLDP: RLDP stopped on slot 0.
*Aug 28 07:46:15.933: %LINK-3-UPDOWN: Interface Dot11Radio0, changed state to down
*Aug 28 07:46:15.950: %LINK-5-CHANGED: Interface Dot11Radio0, changed state to reset
*Aug 28 07:46:15.979: %LINK-3-UPDOWN: Interface Dot11Radio0, changed state to up
*Aug 28 07:50:58.113: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf
*Aug 28 07:59:45.902: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1
*Aug 28 08:06:02.441: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf
*Aug 28 08:14:51.177: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1
*Aug 28 08:21:09.764: %WIDS-4-SIG_ALARM: Attack is detected on Sig:Standard Id:2 Channel:1 Source MAC:000d.9700.c0bf
*Aug 28 08:29:54.463: %WIDS-5-SIG_ALARM_OFF: Attack is cleared on Sig:Standard Id:2 Channel:1

Ether I get these log messages because they are on the same channel or because there is something blocking the other channels.

Can I force a channel change on the LAPs somehow? Not manualy setting the channels, but forcing the LAPs to redo their channel calculation/algorithm.

Best Regards

Philip

Everyone's tags (3)
12 REPLIES

Force channel change on LAP

You need to enable DCA (http://tiny.cc/zrvqjw) under the raido RRM configuration.

Herei s how to configure it: http://tiny.cc/3svqjw.

Your logs show that there is some kind of attacks going on. Do all your APs on same controller? or they are on different contorllers? Do you have rogue APs around? if yes theymay be attacking your APs and that looks like what is causing the issue.

HTH

Amjad

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Re: Force channel change on LAP

DCA is enabled. These APs are on the same controller. Don't see any roge AP in that site.

Hall of Fame Super Silver

Re: Force channel change on LAP

Verify that RDLP is disabled on the WLC? Did you try to manually set the channels and move it back to custom?

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-Scott
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Re: Force channel change on LAP

These changes are not something I can do right away. Need to get an OK with a lot of ppl first.

The APs are working, there are clients connected to them, so any changes have to be done in a service window.

Re: Force channel change on LAP

Are your APs radios channels set to automatic or custome?

Make sure set them to automatic.

DCA to work an AP should hear neighbor APs in power greatr than or equal -80 dBm. If an AP hears neighbor APs with less than -80 dBm that will not affect the channel assignment algorithm.

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Re: Force channel change on LAP

It's automatic.

Didn't know about the -80 dBm limit. That is good information.

AP1 sees AP2 with -83 dBm and AP3 with -72 dBm

AP2 sees AP1 with -81 dBm and AP3 with -80 dBm

AP3 sees AP1 with -64 dBm and AP2 with -83 dBm

Re: Force channel change on LAP

so, that's why channel change is not getting automatically set.

If APs hear each other on less than -80 they will not be in same RF sub-group. So RF config on one AP will not affect the other.

You better go to manual selection, or just like Scott suggested, set the channels to "manual" and provide different channels to the APs then move the config to automatic. The APs will keep their statically configured channel.

(you also have the option to increase raido power [if not max already] or move APs closer to each other but I don't think any of this is applicable to your case).

HTH

Amjad

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Hall of Fame Super Silver

Re: Force channel change on LAP

What code are you running? Also you can force the channel by going into the GUI under Wireless > 802.11 > DCA > Channel Assignment > Freeze > Choose invoke channel update once and hit apply and then you can set it back or leave it.

I have seen issues with the APs that don't change the channel and power and the fix was to upgrade or manually set the channel and power and the place it back to custom.

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-Scott
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Re: Force channel change on LAP

Running 7.0.116.0 at the moment. We are in the process to upgrade to WISM2s (we still have 6xWISM1 left) so we can go up to 7.2.

"Also you can force the channel by going into the GUI under Wireless > 802.11 > DCA > Channel Assignment > Freeze > Choose invoke channel update once and hit apply and then you can set it back or leave it."

I am guessing this will affect all the accesspoints accociated with this controller? That is 490 APs. I was hoping to do it just on these 3 affected APs. I'm guessing I have to manually set it if I want to do it on just these APs.

What good would disabling RDLP do? To me it looks like a good thing to have turned on.

Hall of Fame Super Silver

Re: Force channel change on LAP

Make sure RDLP is disabled

Security > Wireless Protection Policies > Rogue Policies > General

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-Scott
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Hall of Fame Super Silver

Re: Force channel change on LAP

Here is a doc that explains RDLP.

https://supportforums.cisco.com/thread/2031279

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-Scott
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Hall of Fame Super Silver

Re: Force channel change on LAP

Also looks like you need to have a site survey done as your coverage seems to be poor.

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-Scott
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