NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | RETURN VALUE | NOTES | CONNECTION PROPERTIES | INFINIBAND SPECIFIC | IWARP SPECIFIC | SEE ALSO | COLOPHON

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

NAME         top

       rdma_connect - Initiate an active connection request.

SYNOPSIS         top

       #include <rdma/rdma_cma.h>

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

ARGUMENTS         top

       id          RDMA identifier.

       conn_param  connection parameters.  See CONNECTION PROPERTIES below
                   for details.

DESCRIPTION         top

       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         top

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

NOTES         top

       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         top

       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         top

       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         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the rdma-core (RDMA Core Userspace Libraries and
       Daemons) project.  Information about the project can be found at 
       ⟨https://github.com/linux-rdma/rdma-core⟩.  If you have a bug report
       for this manual page, send it to linux-rdma@vger.kernel.org.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/linux-rdma/rdma-core.git⟩ on 2019-11-19.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2019-11-18.)  If you discover any rendering problems
       in this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

librdmacm                        2010-07-19                  RDMA_CONNECT(3)

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