.\" Automatically generated by Pandoc 1.19.2.4
.\"
.TH "IBV_ATTACH_MCAST" "3" "2006\-10\-31" "libibverbs" "Libibverbs Programmer\[aq]s Manual"
.hy
.SH NAME
.PP
ibv_attach_mcast, ibv_detach_mcast \- attach and detach a queue pair
(QPs) to/from a multicast group
.SH SYNOPSIS
.IP
.nf
\f[C]
#include\ <infiniband/verbs.h>

int\ ibv_attach_mcast(struct\ ibv_qp\ *qp,\ const\ union\ ibv_gid\ *gid,\ uint16_t\ lid);

int\ ibv_detach_mcast(struct\ ibv_qp\ *qp,\ const\ union\ ibv_gid\ *gid,\ uint16_t\ lid);
\f[]
.fi
.SH DESCRIPTION
.PP
\f[B]ibv_attach_mcast()\f[] attaches the QP \f[I]qp\f[] to the multicast
group having MGID \f[I]gid\f[] and MLID \f[I]lid\f[].
.PP
\f[B]ibv_detach_mcast()\f[] detaches the QP \f[I]qp\f[] to the multicast
group having MGID \f[I]gid\f[] and MLID \f[I]lid\f[].
.SH RETURN VALUE
.PP
\f[B]ibv_attach_mcast()\f[] and \f[B]ibv_detach_mcast()\f[] returns 0 on
success, or the value of errno on failure (which indicates the failure
reason).
.SH NOTES
.PP
Only QPs of Transport Service Type \f[B]IBV_QPT_UD\f[] may be attached
to multicast groups.
.PP
If a QP is attached to the same multicast group multiple times, the QP
will still receive a single copy of a multicast message.
.PP
In order to receive multicast messages, a join request for the multicast
group must be sent to the subnet administrator (SA), so that the
fabric\[aq]s multicast routing is configured to deliver messages to the
local port.
.SH SEE ALSO
.PP
\f[B]ibv_create_qp\f[](3)
.SH AUTHOR
.PP
Dotan Barak <dotanba@gmail.com>
