Storage Spaces Direct (S2D) supports ethernet connectivity using SFP+ or Base-T. Microsoft requires 10GbE for intra-cluster communication to avoid the network becoming a performance bottleneck.
S2D supports several network bandwidths: 10, 25, 40 and 100 Gb Ethernet. Although it is not mandatory, a network compliant with RDMA (RoCE or iWARP) brings the best performance.