Upload a .txt file with three columns (tab or spaces):
MACAddress, Description, IdentityGroup
MACAddress Description IdentityGroup
50:0C:00:03:00:00 Printer vlan_100
AA:BB:CC:DD:EE:FF Laptop vlan_200
11:22:33:44:55:66 Phone vlan_100
77:88:99:AA:BB:CC Tablet vlan_300
After uploading, click “Download CSV” to get your import file for Cisco ISE.