Veritas Client on ETH2

My Backupserver is connected to ETH2 on the DSS.
The IP-Adrresses are:

DSS:
ETH0: 192.168.100.220 255.255.255.0
ETH2: 192.168.120.220 255.255.255.0

Backup W2k3 with BackupExec 11d:
LAN1 192.168.100.251 255.255.255.0
LAN2 192.168.120.251 255.255.255.0

Now I would like to use the connection via ETH2 (192.168.20.X).

I've configured DSS to use the Server-IP 192.168.120.251, set the password.

When I open my BE, i can see the DSS, select the shares and do a backup.
The only problem is that the data is passed on ETH0. When I disconnect LAN1 on the Windows machine, i can't backup anymore :-(

Is there a way tho configure the BE-client to use an other NIC?

I would like to shut down the ETH0-LAN1 connection and use the ETH2-LAN2 connection only for my backups.

Thanks, Marc