Netbackup 8.1 integration with data domain 6.1.x

Hi,

we have a customer who has master/media NetBackup server on the same host and we want to integrate data domain to it. we have opened a firewall request from the master/media server to data domain on 111, 2049, 2051 and 2052. But do we have to open it bi-directional?

Thanks,

Chandan