Question regarding AP Group configuration

[Scott Fella]

Question regarding AP Group

I have two WiSM each located on a seperate 6509. I have an SSID that I want to map to four vlans, because of the amount of users. Lets say vlan 10, 11, 12 and 13 for SSID 'TEST'. I have to create one group and map SSID 'TEST' to each dynamic interface... correct? If that is correct, each WiSM has two controllers, so I would need to create four dynamic interfaces on each controller?

I was told that I could just configure vlan 10 on controller A, vlan 11 on controller B and so on. But the issue I have is if one controller fails. No other controller has an interface on that subnet... Is that correct?

[globalnettech]

Hello,

you can reduce the number of interfaces you need to create by putting both controllers on each WiSM in a Link Aggregation Group, and then configure the interfaces on that group. Check the link below and scroll down to 'Link Aggregation':

Controller Menu Bar Selection

http://www.cisco.com/univercd/cc/td/doc/product/wireless/hahcont/contc.htm

HTH,

GNT

[Scott Fella]

I'm looking more for ap group configuration. if I have 4 subnets (vlan 10-13) that I map to an SSIS 'TEST', should I configure each controller(2 per WiSM) each having 4 dynamic interfaces for each subnet (vlan 10-13). Each controller is configured with LAG.

[Stephen Rodriguez]

Yes program all four modules with the four dynamic interfaces, then you set the WLAN to the management interface. When you setup the AP groups, you point the group at the correct dynamic interface

[Scott Fella]

Thanks! So AP Groups are only used when you have multiple vlans that need to be mapped to a single SSID. I was told that AP Groups are used to group different SSID's together which is opposite of what I wanted to do.

[MARK HEUZENROEDER]

Hi,

This was a useful discussion for me (makes up for deficien Cisco doco).

What I 'LOVE' about Cisco doco. is that you'll only find decent discussion about a given feature under the version number this feature was introduced in. Fortunately Google takes up their slack.

For AP Groups, I could only find good explaination under WLC s/w version 3.0,

The other constant Cisco theme is completely different names for the same thing.

"AP Groups" is the term used in the GUI but "Site-Specific VLANs" is used in the doco.

See,

http://www.cisco.com/en/US/products/ps6366/prod_bulletin0900aecd802d2742.html

[Scott Fella]

I know what you mean... I did see that article and that is why when I deploy LWAPP where I have different subnets per floor and a single SSID (can also have other ssid's) I use AP Group. I see deployments where other engineers create multple AP Groups using some of the same SSID's but one group would not have one of the SSID's entered. Example: Wireless existing, wireless future, wireless secure, stuff like this. I wonder if there is a right way or not and also if this is needed at all. Thanks for the input!

[hmhrcook1]

Do all four controller dynamic interfaces have different IP addresses on same subnets as lan VLANs?. If so would there not be an interuption in service if a controller went down, and an AP had to switch to another controller with different dynamic interface IP?

[Scott Fella]

Each controller has different IP Address but each each ssid is mapped to a dynamic interface which all are in the same subnet. I was told that only use ap groups when you only have one ssid created. These ssid would span a campus for example, multiple vlans but same ssid.

[zhenningx]

How about create just one dynamic interface on each controller, like vla10 on controller A, vlan11 on controller B... And you map SSID to the dynamic interface on each controller. So you do not need four dynamic interfaces on each controller. In this set up, if one controller fails, the clients will get different IP from another controller, if that is acceptable.

Also another post said we can group two controllers in one wism into one LAG. I did not find how to do that in document. Could some one explain that in more detail? Thanks.

[Scott Fella]

The only problem I see is that if you are associated to an ssid on one controller (vlan 10) and then that controller drops off and and the ap joins another controller, the ssid will be on a different vlan (vlan 20) and the user will have to release and renew their ip. I don't know if you can group the two controllers into one... you would then have to group the service ports.

Have you used ap groups and when and why did you use it. Cisco has told me not to use ap groups if you have more than one ssid on the wlan. ap groups does not help when ap's loose their connection to their primary controller... users will noticed network issues until the ap has joined another controller..... has anyone heard or experienced anything different?

[zhenningx]

I did not use AP group. But I think even with AP group, users will still notice when the controller is down. Because when controller is down, APs will reboot and join the 2nd controller. User will lose the signal for short time. And user still need reauthentication, because the 2nd controller has no way to know the user is already authenticationed when the anchor controller crashed. The reauthentication may be transparent to user when using WPA, but user will need to re-login when using web auth.

[jakew]

Do NOT group the 2 controllers in 1 WiSM into a single Etherchannel on the 6K(LAG). You can create 2 port-channels that are identically configured, but if you create one Etherchannel, it'll never work correctly.