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Roaming between AP Groups on same controller

Hi experts,

I have the following WLAN setup:

- 3 WLC's

- 10 floors

- 10 IP-subnet, subnet per floor

- 10 AP-Groups

Floor 0    AP_GROUP_0     SUBNET_0      WLC1

Floor 1    AP_GROUP_1     SUBNET_1      WLC2

Floor 2    AP_GROUP_2     SUBNET_2      WLC3

Floor 3    AP_GROUP_3     SUBNET_3      WLC1

Floor 4    AP_GROUP_4     SUBNET_4      WLC2

Floor 5    AP_GROUP_5     SUBNET_5      WLC3

Floor 6    AP_GROUP_6     SUBNET_6      WLC1

Floor 7    AP_GROUP_7     SUBNET_7      WLC2

Floor 8    AP_GROUP_8     SUBNET_8      WLC3

Floor 9    AP_GROUP_9     SUBNET_9      WLC1

Floor 10   AP_GROUP_10    SUBNET_10     WLC2

Every time a user roams from Ap on Floor0, to Floor3, L3 connectivity is gone.

The user first connects on an AP on Floor0, which is bound to AP-Group0 and IP-subnet0, travels to Floor3,  the WLC will perform a intra-controller roam, and updates the AP entry in the MSCB table, but it'll keep the IP address. But, the AP-group on Floor3 is different, and so is the IP-subnet bound to it. So the user will try to communicate with it's old IP address (Floor0) within the new Ap-Group3.....

Is this working as designed and should I change my AP-Groups, or can I change this behaviour...

I suppose this would be a normal L3-roaming decision... and things should work out just fine?

"DHCP addr assigned required" option, will not work..

Rasika Nayanajith
VIP Mentor

I would not design in this way. Near by floors should be go to same WLC to minimise the inter-controller roaming.

Also if possible create a large subnet and get rid of this subnet per floor design.



Hi Rasika,

Getting rid of the subnet_per_floor design would definately fix the problem. But, I don't want to enlarge the current subnets, so expanding the existing subnets is no option.

Best option would be an interface-group, and round-robin the clients within the different interface members. But then I will loose the mapping between user and floor.

What I would like to know; is this the way it works? Like, intra-layer3-roaming is not supported in this setup? Or, should it work in the way that when roaming between AP-groups, the IP address whould be updated also?

Client IP won't change depend on the roam type (inter or intra controller) as long as smooth wireless coverage is there between floors.

Client IP determine by where the device get associate to wireless network in the first place (most of clients may get level 1 IPs if they come there first and then go upto other levels.



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