To ZD's, VLAN 0 is untagged, so you might have an untagged management VLAN from your central datacenter with ZD located,
out to all 20 remote sites, so you can talk to the APs there. ZD's talk to APs using encrypted LWAPP. If you have 3 WLANs
configured, all on different VLANs, all tunneled back to the ZoneDirector, you only need those Client VLANs at the ZD, not at the
remote AP locations. So your Head Office and Remote Branch Offices, only need the one untagged VLAN that's used for ZD/AP
management.