Creating LAG on WLC remaps WLANs

[tllewell55]

We have 5508 controllers connected with single links to the upstream switches. We'd like to add a link and set them up as LAGs. According to the configuraton doc at https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-5/config-guide/b_cg85/ports_and_interfaces.html this will remap all of the SSIDs: 

"When you enable LAG, all dynamic AP-manager interfaces and untagged interfaces are deleted, and all WLANs are disabled and mapped to the management interface."

So this will either map all of our WLANs, including the unsecured Guest SSID, to the management VLAN, or, move all the interfaces to the port the management vlan is on, and delete the management vlan, so we won't be able to manage the box except by the console port. Either way, it sound messy and potentially dangerous. Or is this just a really badly written sentence? So just what does happen here?

[Haydn Andrews]

This is one of the reasons i alway enable LAG when i build the WLC its so much easier and non impacting to do it then.

When you enable LAG effectively you have a single link out of the WLC. You need to map interfaces to VLANs on that link.

I believe if your WLAN is already pointing to a VLAN Tagged dynamic interface it will stay the same on the LAG port/s.

What you cant do is have multiple untagged interfaces.

After the change, make sure you have a dynamic interface mapped to each VLAN you require each WLAN to be sent to, and make sure each WLAN is mapped to that dynamic interface.

You then can keep the management interface for management only (including AP Manager).

If your current setup for the Guest network is a physical cable from the WLC to behind a firewall then you will not be able to do this with LAG and will need to look at other Guest methods like anchoring.

[tllewell55]

Thanks for the reply. The more I think about it, the more the statement that the WLANs will all be mapped to the management interface makes no sense. But I think what we'll do is disable all the WLANs, drop the big one, and see what happens.

Our management connection is via a VLAN, what they call a "dynamic interface" in WLC parlance, that is not mapped to an SSID. 

I guess I'll be keeping a console cable handy, too.

[Daniel Ordóñez Flores]

Hi @tllewell55 

Hmmm not sure but I think it talks about AP-Manager Interfaces, on 5508 this interface does not exist instead use management interface. I did a lot of LAG with older versión 8.3 and after that, I restart the WLC everything works well.

Tha dinamic interface remain..

[tllewell55]

Thanks, Daniel. All of our WLANs are assigned to dynamic interfaces so your answer sounds plausible. As to the AP-manager interface, yes, it's some kind of virtual, non-configured endpoint, but one doc I read said it's the endpoint for the CAPWAP tunnel, so disabling it makes no sense at all. So all of that sentence is incomprehensible. But, since I've pointed it out to my management, it's going to make it a lot tougher to get a maintenance window to do this (it's a seasonal issue for my organization).

[Daniel Ordóñez Flores · Accepted solution]

Hi @tllewell55 

Absolutely, Agree.

But again, We did this in 8.3 if my memory works. Just enable LAG, restar the WLC and everything should be work just fine. In a remote case that you need to remap your interfaces it could be take it 5-10 min aprox.

[tllewell55]

Well, that is certainly what I hope happens. The worst-case-scenario side of my brain says schedule an hour and brush up on CLI commands. ;-)