9100 AP transitioning from local to Flexconnect mode in N+1 scenario?

[gloriachn29]

Hello experts, 

We are considering deploying N+1 WLC in a regional basis. The requirement is to have a backup WLC in the regional site in case the local WLC presents a failure or is unreachable for long periods of time. My question is if such an AP could move from Central switching to a Flexconnect local switching operation when it associates to the redundant regional controller?

This is because of WAN considerations but of course I am considering other alternatives as solutions. Thanks in advance

[Flavio Miranda]

@gloriachn29 

 What determine if local switching or central switch is the SSID but, you may need to map the WLAN-to-VLAN on the AP depending on your scenario and that could be an issue.

[gloriachn29]

Thanks Flavio.

That is one of the considerations I wanted to validate. The operation of the AP port would need to change from an access port (local mode) to a trunk (flexconnect). On the AP side I understand that the port changes but on the switched side is there something to change from access to trunk? Do the APs support DTP?

Regards,

Gloria

[Flavio Miranda]

The AP supports DTP as you dont need to setup the AP´s interface as trunk, only on the switch side is required. But, you do need to properly map the WLAN to VLAN if you have more than one SSID and need them to be send to differents vlans. And this is something you need to do after the AP migration. It will not Inheritance this from the WLC and will lose the configuration as soon as it switch between WLC.

 The switch side is not a problem, the way I see it, as you can leave the port in trunk mode with native vlan on it. Either the AP in flexconnect or local mode, it will work. The problem I see for this scenario is the WLAN to VLAN Map on the AP  migration.

For AirOS, as I dont know which WLC do you have, this is the place where you need to manually add the WLAN to VLAN mapping.

[jmanzanera]

@gloriachn29  
The solution you want to implement it will work, but under my point of view it is import to know which kind of WLC are you using. Are you already moved to WLC9800 or do you have AireOS systems?

[gloriachn29]

Thank you @jmanzanera , I am running mostly IOS XE with Cat9800 but some WLC are remaining in AirOS (5508 and 8510) which are in process of migration 

[jmanzanera · Accepted solution]

If this is the case, I highly recommend to use only WLC9800 only to setup this solution.
With the WCL9800 you can use the tags and move the AP between local and flex solution using the primary and secondary wlc configuration on each AP.

My idea will be:
- Not use tag persistency (as you are going to move between 2 types of architectures).
- Configure the local WLC with local TAGS
- Configure the remote WLC with remote TAGS (Flex tag needs to be used here).
- Configure all the switch ports in trunk mode (the only problem here is that you will need to use all the VLANs that you want to use on the trunk port all the time - not sure if your security team will allow this).
- For AP tag profile I recommend to use the filter option with regex (depending on the AP name) 

Be aware that you will need a different site-tag for the local and remote controller for each location.
My understating is that WLC9800 will provide easier configuration (and you can use the same IOS-XE version with no issues) - When the AP will be moved from local to remote WLC a reboot of the AP will be needed.

On the other hand, if you are not using any specific feature that only works in local mode, the other option is to use Flex in all the WLC (and it doesn't matter if you are in local or remote WLC)

[balaji.bandi]

I am thinking you have Cat 9800 Controllers, if you have N+1 deployment, you can other controller any where, can be onsite or remote or virtual.

[Rich R · Accepted solution]

Fantastic answer from @jmanzanera on how to do it with different local and remote configs but I think you're making it too complicated for yourself doing it that way because:
1. You need to maintain 2 separate sets of configs and you won't know you've made a mistake in the remote config until you need to use it, unless you test after any change.
2. Switching the APs between 2 different sets of tags increases your risk of hitting bugs because there have been a number over the years affecting APs when they have different WLAN configs on changing between WLCs, and I'm sure there will be more with current software quality we are seeing.

The final paragraph "On the other hand, if you are not using any specific feature that only works in local mode" is what I think the correct answer is.  If it all possible, build the solution to work with flexconnect local switching all the time then have the same config on local and remote WLCs.  The APs won't need any reboot when switching between WLCs and you'll be using the exact same config on both WLCs so reducing your difficulty in keeping the configs in sync with each other, and reducing the risk of bugs caused by changing tag and WLAN configs.