[ofa-general] how to write a IB user level multicast application

[Andrew Friedley]

Dotan Barak wrote:
> In the following URL you can find a very simple example on how to use 
> multicast:
> https://svn.openfabrics.org/svn/openib/trunk/contrib/mellanox/ibtp/gen2/userspace/useraccess/multicast_test/multicast_test.c 

I seem to be missing v1.h on my OFED v1.2 nightly install, where can I 
find it?

> this test doesn't send an SA query (to get the multicast props) or an SA 
> multicast join (to make the SM configure the subnet to make the port 
> that this QP is attached to) to get the multicast messages.
> 
> This example will work on a back-to-back topology.

An alternative that I've had pretty good success with is to use the RDMA 
CM.  It uses an IP(v6) abstraction, does the SA queries/joins for you, 
and also supports selection of an unused multicast address if you join 
the '0' address (and port? not sure if its required, I always zero it). 
  Check out the 'mckey.c' example included with the RDMA CM source, it 
will likely answer your questions.

Andrew