VLAN Pools
Network administrators prefer to keep subnet sizes down to what is commonly referred to as class C network. This is a network with a subnet mask of /24 (255.255.255.0), yielding 253 user devices per subnet. This size is considered manageable and will limit the broadcast domain size. In networks where this subdivision needs to be logical as opposed to physical VLANs are employed to limit broadcast domain size.
One legacy methodology for dividing up large groups of wireless users is to take a set of APs and have all users associated with those APs placed in a single VLAN. Each set then would have one of the user VLANs associated with it. This method works if the user count never goes above the user count limit for that subnet; and if users have no need to roam outside of the AP group. However, this method tends to fail when large groups of users need to meet in a single location like a lecture hall, or an ‘all hands’ meeting.
Mobility controller 
VLAN 10
VLAN 20
VLAN 40 |
VLAN 30
30 Mobility Controller and Access Point Deployment | Campus Wireless Networks Validated Reference Design Version 3.3 Design Guide |
