[openib-general] IB mcast question

[Steve Wise]

On Mon, 2006-08-14 at 12:42 -0700, Roland Dreier wrote:
>     Steve> However, if I run 2 instances of the app that reads mcasts
>     Steve> and dumps them to stdout, I only get the mcast packets
>     Steve> delivered to one of the applications.  Namely the first one
>     Steve> who joins the group seems to get the mcasts.  I know for
>     Steve> UDP/IP multicast, all applications bound to the same port
>     Steve> and joined to the IP mcast addr will get a copy of incoming
>     Steve> mcast packets.  Is this not true for IB mcast?  It appears
>     Steve> not based on my tests...
> 
> This should work -- multicast packets should be replicated to all
> attached UD QPs.  There is likely a bug in the librdma multicast support.
> 

So is this replicating done in the mthca hca?  

Since one app is getting the mcast packet, can I assume the opensm code
is doing the right thing switch/port wise?

Should the SM get join requests for both applications that join the
group on the same host?  Or only the first one?

Steve.