> Furthermore, if you use RDMA over Ethernet, you are using infiniband at a low level. RoCE which enables it was originally called Ethernet over infiniband.

This is wrong.

RDMA over Ethernet is... RDMA over Ethernet. There is no Infiniband involved.

RoCE was motivated by supporting RDMA, which was then an IB-only feature, over regular Ethernet. The user-level APIs are the same (verbs), but the underlying architecture is all different --- it is traditional Ethernet with link-level flow control to make it lossless (pause frames).