Also another question about this.
Usually a device while roaming still gets the same VLAN it got during initial connection. Let's say for example, I first connect to an AP and get VLAN 10 from VLAN pooling, so while moving around the coverage area my device roams through several APs and always get VLAN 10. If a second device connects and gets VLAN 20, while roaming still gets VLAN 20.
If a SZ goes down, and VLAN pooling still works because it's made at AP side, what happened to the VLAN when roams to a different AP? How the other AP knows that I first got VLAN 10? In this case will I receive different VLAN every time I roam?