I have two Windows servers, directly connected with Mellanox ConnectX-3 without switch infrastructure between.
Is this a supported scenario with functioning RDMA/RoCE?
If so, do I still need to implement Datacenter Bridging in Windows or is only required when switches are in play?
RoCE/RDMA is a network communication protocol therefore can be used within B2B (back-to-back) configuration or over switch connection. .
As DBC is related to ethernet network for data center environment, you'd probably need to use a switch that can share more that one cluster node in the network...but basically it is feasible in B2B topology as well