关于AD账号的权限，ISE 1.2的user guide是这样写的：
The Active Directory username that you provide when joining to an Active Directory domain should be predefined in Active Directory and must have one of the following permissions:
– Add the workstation to the domain to which you are trying to connect.
– On the computer where the Cisco ISE account was created, establish permissions for creating or deleting computer objects before joining Cisco ISE to the domain.
– Permissions for searching users and groups that are required for authentication.
After you join Cisco ISE to the Active Directory domain, you will still need these permissions to:
– Join any secondary Cisco ISE servers to this domain
– Back up or restore data
– Upgrade Cisco ISE to a higher version, if the upgrade process involves a backup and restore
user guide：
http://www.cisco.com/c/en/us/td/docs/security/ise/1-2/user_guide/ise_user_guide/ise_man_id_stores.html#pgfId-1317829
