How NetBackup 8.1 or later hosts communicate with NetBackup 8.0 and earlier hosts
NetBackup 8.1 or later hosts can communicate with other 8.1 or later hosts only in a secure mode. For 8.1 or later host to communicate with hosts at 8.0 or earlier, you need to allow insecure communication.
By default, the Enable insecure communication with NetBackup 8.0 and earlier hosts option is enabled. The option is available on the Settings > Global security > Secure communication tab.
If you disable the option to allow only secure communication, you must restart the NetBackup services on the primary server to terminate any insecure communications and allow only secure communications.
During insecure communication, the NetBackup host first connects to the primary server for host validation. The primary server verifies whether insecure communication is enabled or not. If the option is enabled, the communication between the two hosts is established. If the option is disabled, the communication is dropped.