In RC, Responses Are Expected

In the RC transport service type, the requester QP's SQ Logic expects to receive a confirmation from the responder QP's RQ Logic that each request packet of the message transfer has been successfully received and acted upon by the responder QP's RQ Logic. The requester QP's SQ Logic cannot signal a message transfer completion to software until it has received the Ack corresponding to the message's final request packet (in the case of a Send or RDMA Write), or RDMA response packet (in the case of an RDMA Read), or the Atomic response packet, in the case of an Atomic RMW).