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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 data-
       gram 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  rou-
       tine.

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	opera-
	      tions that the local side	will accept from the remote side.  Ap-
	      plies only to RDMA_PS_TCP.  This value  must  be	less  than  or
	      equal  to	the local RDMA device attribute	max_qp_rd_atom and re-
	      mote RDMA	device attribute max_qp_init_rd_atom.  The remote end-
	      point can	adjust this value when accepting the connection.

       initiator_depth
	      The  maximum  number  of outstanding RDMA	read and atomic	opera-
	      tions 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  re-
	      mote  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 Infini-
       Band 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_discon-
       nect(3),	rdma_listen(3),	rdma_get_cm_event(3)

librdmacm			  2010-07-19		       RDMA_CONNECT(3)

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

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