Can I Use a direct connection between two Data Domain interfaces for replication

We have two data domain DD890 and DD9300 We want to replicate and migrate data from DD890 to DD9300 using Mtree/Directory replication. We have 10Gb FCoE Modules on both systems. The systems are side-by-side in the same Data Center. Can we use direct connection between these interface and configure replication between them ? I enabled interfaces assigned IPs and plugged in the cable on either systems but the links are not Up. Do I need a switch or is it possible to use direct connect between DDs ?