RDMA_CONNECT(3)          Librdmacm Programmer's Manual         RDMA_CONNECT(3)

NAME
       rdma_connect - Initiate an active connection request.

SYNOPSIS
       #include <rdma/rdma_cma.h>

       int rdma_connect (struct rdma_cm_id *id, struct rdma_conn_param
       *conn_param);

ARGUMENTS
       id          RDMA identifier.

       conn_param  connection parameters.  See CONNECTION PROPERTIES below for
                   details.

DESCRIPTION
       For an rdma_cm_id of type RDMA_PS_TCP, this call initiates a connection
       request to a remote destination.  For an rdma_cm_id of type
       RDMA_PS_UDP, it initiates a lookup of the remote QP providing the
       datagram service.

RETURN VALUE
       Returns 0 on success, or -1 on error.  If an error occurs, errno will
       be set to indicate the failure reason.

NOTES
       Users must have resolved a route to the destination address by having
       called rdma_resolve_route or rdma_create_ep before calling this
       routine.

CONNECTION PROPERTIES
       The following properties are used to configure the communication and
       specified by the conn_param parameter when connecting or establishing
       datagram communication.

       private_data
              References a user-controlled data buffer.  The contents of the
              buffer are copied and transparently passed to the remote side as
              part of the communication request.  May be NULL if private_data
              is not required.

       private_data_len
              Specifies the size of the user-controlled data buffer.  Note
              that the actual amount of data transferred to the remote side is
              transport dependent and may be larger than that requested.

       responder_resources
              The maximum number of outstanding RDMA read and atomic
              operations that the local side will accept from the remote side.
              Applies only to RDMA_PS_TCP.  This value must be less than or
              equal to the local RDMA device attribute max_qp_rd_atom and
              remote RDMA device attribute max_qp_init_rd_atom.  The remote
              endpoint can adjust this value when accepting the connection.

       initiator_depth
              The maximum number of outstanding RDMA read and atomic
              operations that the local side will have to the remote side.
              Applies only to RDMA_PS_TCP.  This value must be less than or
              equal to the local RDMA device attribute max_qp_init_rd_atom and
              remote RDMA device attribute max_qp_rd_atom.  The remote
              endpoint can adjust this value when accepting the connection.

       flow_control
              Specifies if hardware flow control is available.  This value is
              exchanged with the remote peer and is not used to configure the
              QP.  Applies only to RDMA_PS_TCP.

       retry_count
              The maximum number of times that a data transfer operation
              should be retried on the connection when an error occurs.  This
              setting controls the number of times to retry send, RDMA, and
              atomic operations when timeouts occur.  Applies only to
              RDMA_PS_TCP.

       rnr_retry_count
              The maximum number of times that a send operation from the
              remote peer should be retried on a connection after receiving a
              receiver not ready (RNR) error.  RNR errors are generated when a
              send request arrives before a buffer has been posted to receive
              the incoming data.  Applies only to RDMA_PS_TCP.

       srq    Specifies if the QP associated with the connection is using a
              shared receive queue.  This field is ignored by the library if a
              QP has been created on the rdma_cm_id.  Applies only to
              RDMA_PS_TCP.

       qp_num Specifies the QP number associated with the connection.  This
              field is ignored by the library if a QP has been created on the
              rdma_cm_id.  Applies only to RDMA_PS_TCP.

INFINIBAND SPECIFIC
       In addition to the connection properties defined above, InfiniBand QPs
       are configured with minimum RNR NAK timer and local ACK timeout values.
       The minimum RNR NAK timer value is set to 0, for a delay of 655 ms.
       The local ACK timeout is calculated based on the packet lifetime and
       local HCA ACK delay.  The packet lifetime is determined by the
       InfiniBand Subnet Administrator and is part of the resolved route (path
       record) information.  The HCA ACK delay is a property of the locally
       used HCA.

       Retry count and RNR retry count values are 3-bit values.

       The length of the private data provided by the user is limited to 56
       bytes for RDMA_PS_TCP, or 180 bytes for RDMA_PS_UDP.

IWARP SPECIFIC
       Connections established over iWarp RDMA devices currently require that
       the active side of the connection send the first message.

SEE ALSO
       rdma_cm(7), rdma_create_id(3), rdma_resolve_route(3),
       rdma_disconnect(3), rdma_listen(3), rdma_get_cm_event(3)

librdmacm                         2010-07-19                   RDMA_CONNECT(3)