Lost VLAN Mapping on WLC 5508 (Flexconnect)

[jguandalini]

Hi guys, I have a WLC 5508 and some AIR-LAP1131AG-T-K9 all in flexconnect configuration.

The problem is that 1130 Access Points lost the VLAN Mapping configuration without reason, simple change the vlan mapping to 999 and I need to reconfigure that.

I search in some documents on cisco.com but I can't find anything about this issue.

Could you help me please?

Thanks guys.

[Scott Fella]

Tommy,

WLAN to Vlan mappings usually never gets lost if you don't have another WLC. What vlan is the mapping changed to? Typically of something happens to the Ap, the WLAN to vlan mapping might assign the vlan that the WLAN interface is on in the WLC. So in the WLC, look at the interface that your WLAN is assigned to.

I usually will try to have that WLAN have the same vlan id everywhere even locally. This is where FlexConnect AP's will default their vlan mapping on the WLAN to. Look at the ap join time and see if that is less than the ap uptime. This can mean maybe that the ap lost the connection to the WLC and then joined and maybe that's where it lost is mappings.

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[tommy]

Hi Scott

Thanks for the answer.

We have around 350 ap's, in 50 different locations (customers). The WLC is running AirOS 7.3.101.0.

Every WLAN is configured to a dummy interface, with the vlanID 2222.

This is the VlanID that the Wlan to vlan mapping got “lost” to.

Unfortunately, I am not able to see the right join time, because the WLC’s was booted. (After the error occurred). Next time I see this, I will look at the join time.

Every location (costumers) has two SSID (guest and employee). The employee network has two vlans (PC’s and BYOD). We are using NPS rules to select witch VLAN the device connectes to.

So in the FlexConnet settings, we do a WLAN to vlan mapping:

• GUEST to vlanID
  
• PC’ to vlan ID 5
  

And in the FlexConnect group we but in the vlan ID for BYOD.

Do you now if the AP stores this to configurations different (flash or RAM)?

[Scott Fella]

This is stored in nvram and should not get lost.  If there is a glitch or the AP has lost connectivity to the WLC, it should retain the vlan.  I did see issue with this with previous code version, but not with later versions.  You can try to upgrade, or search the forum for "flexconnect vlan mapping" and see what code versions others have ran into this issue.  If you have NCS or Prime, you can always push a template out to all the AP's so that in case they do have the wrong vlan info, the template will correct that.  You can also just cut and paste from the spreadsheet I provided above.

Thanks,

Scott

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[Mark Withers]

I was able to modify that spreadsheet to use a list of APs in another tab, 20 at a time (didn't want to overload SSH buffer), to generate the commands to set the VLANs for multiple WLANs. Had same issue, random VLAN mapping lost (box not checked in WISM2 GUI, or box checked but all VLANs defaulted to VLAN 1). Code versions 7.0.235.0 and 7.4.100.0.

Supposedly this happens when the configs on your access controllers aren't absolutely, positively, 100% identical for the WLANs and VLANs... And I concur to an extent that matching configs up certainly did mitigate the issues.

Our environment had multiple WLC's though, seems yours only had one.

[tommy]

Hi Scott

I have heard that there can be a bug in the AireOS with HA and that Cisco is planning to release a fix for this..Hopefully pretty soon.......

In the meantime, I think I will use templates in PI ......

[Scott Fella]

There are bugs with HA:) it will be a. While before people test with v7.4 MR1 or v7.5 with HA.

Pushing out the templates through NCS/PI is the easier way and I will tell you, I always do this just to make sure. I will use NCS/PI template also if people start complaining and I see one Ap with the wrong vlan mapping. I would push this out to all the AP's instead of looking for AP's that had the wrong mapping.

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[Mark Withers]

We started doing this as a daily policy, pushing out VLAN mapping before sites open. This GREATLY mitigated our VLAN mapping issues. Good to see someone smarter than us using a similar approach!

[Scott Fella]

Haha... I don't think I would be using if if the vlan mappings were stable:). They should have a static entry checkbox to keep your settings no matter what. That would be the preferred way:)

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[ajjaymats]

Hello Scott,

Cannot find the excel file. the text file that you have mentioned is available but not the excel file.

please share again.

Regards,

Aj

[Scott Fella]

I will try to find it or create a new one maybe tomorrow. 

[markwi001]

-Scott

Is this still a viable solution?  We are on a 5508 WLC with 8.3.141 code and QTY 85 AP3800.

I find missing native VLAN, and Flexconnect VLANs from time to time.

Thank You,

Mark

[Scott Fella]

It is still a solution. Just create the commands to create the wlan to vlan mapping is all you need. In the past, I created a WCS/NCS/Prime CLI template and pushed out the commands every night to ensure that in the morning, things were working fine. For those customers whom didn’t have a management tool, I gave them the cli commands and when a users was complaining about being connected and not having network access, they just ran the whole script because there might be other AP’s Gavin the same issue. 

[markwi001]

-Scott

Thank you,  very helpful.  I thought that maybe a new version of code may have eliminated this problem.  

Has anyone ever talked about the difference with setting this up in a flexconnect group as opposed to individual vlan mappings per AP.  

TAC indicated that the preferred method was to use flexconnect groups to assign the VLANs per WLAN.

Just curious what your take is on the difference.

Thank you very much Scott.

Mark

[jlhainy]

I have been using Lightweight AP Templates to deal with this issue for years.  The cool thing with those templates is that you can schedule them, so that my templates run early in the am before business starts and all has been well.  I have not had to deal with this for quite some time.

I also have run into the flexconnect groups having wlan to vlan mappings.  This feature wasn't always there.  I would like to see a good discussion on the pros and cons to using flexconnect groups vs. AP templates to deal with wlan to vlan mappings.

Instead of using a script or a scheduled template, has anyone used a flexconnect group to mitigate their issue?

[Yahya Jaber]

Hi,

may i ask you to try this workaround, and see if it works?

1.create Fake interfaces on both WLC's "with any IP" but make sure to give them the same VLAN that you have on the VLAN mapping of the AP.

2.on the AP group, assign that Fake interface for that SSID. "even if you have an interface with same VLAN, you can assign it instead of the Fake one"

3.as normal, change the VLAN mapping on the AP to the desired VLAN.

4.after you do that on both WLC, test and do a failover for one AP.

i tested that today, and it worked for me.

please let me know if that workaround fixes your issue or not.