Hi DoJo,
I'm deploying a fully selft managed DMS installed in virtual machines based on this network architecture.

My question is whether it's possible, and worthwhile, to configure a dedicated network interface just for communication between DataMiner nodes. In my diagram, this would be VLAN 13
L2_Cluster_DataMiner_Agents. Or would VLAN 12
L2_DataMiner_Network be enought?
How do I configure DataMiner so that traffic between DataMiner nodes uses a specific network interface?
Thank you very much.
DataMiner relies on the Windows OS / Routing table to route traffic so no special configuration is needed in DataMiner. Configuration is only needed on the windows server itself.
Each DMA will route its requests through the appropriate NIC based on the IP addresses/hosts involved. All you will need to ensure is that the subnet masks are correctly configured.
Segmenting to have a DMS cluster network is a feasible approach. This network will then be used by the agents for synchronization, clustering and related services.