If you intend to use Data Domain with OST plugin and all of its functionality, then you need the NetBackup Data Protection Optimization Option license.
If we just want to use EMC data domain deduplication and not other features then do we require any license for netbackup?
How will you configure DD with NBU?
As Basic or Advanced disk?
Using NFS/CIFS network share or OST?
Which features are you buying with the DD?
Will you be duplicating/replicating between DD's?