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At this moment, the Infinband node supports RDMA_PS_TCP. It is also possible to use RDMA_PS_UDP:

RDMA_PS_TCP
Provides reliable, connection-oriented QP communication. Unlike TCP, the RDMA port space provides message, not stream, based communication.

RDMA_PS_UDP
Provides unreliable, connectionless QP communication. Supports both datagram and multicast communication.

RDMA_PS_TCP and RDMA_PS_UDP are mapped to the Queue Pair as IBV_QPT_RC, IBV_QPT_UD, respectively:

From librdmacm/cma.c:

int rdma_create_id(struct rdma_event_channel *channel,
		   struct rdma_cm_id **id, void *context,
		   enum rdma_port_space ps)

/ ** SNIP **/

	qp_type = (ps == RDMA_PS_IPOIB || ps == RDMA_PS_UDP) ?
	IBV_QPT_UD : IBV_QPT_RC;

The operations the HCA can perform in unreliable connectionless mode are limited (see table below), but since our Infiniband node relays solely on IBV_WR_SEND(_WITH_IMM), this would work perfectly fine for us.

OPCODE | IBV_QPT_UD | IBV_QPT_UC | IBV_QPT_RC ----------------------------+------------+------------+----------- IBV_WR_SEND | X | X | X IBV_WR_SEND_WITH_IMM | X | X | X IBV_WR_RDMA_WRITE | | X | X IBV_WR_RDMA_WRITE_WITH_IMM | | X | X IBV_WR_RDMA_READ | | | X IBV_WR_ATOMIC_CMP_AND_SWP | | | X IBV_WR_ATOMIC_FETCH_AND_ADD | | | X