[openib-general] RDMA CM multicast

[Sean Hefty]

>>Is this how it works with sockets?
> 
> 
> I'm not aware of IP multicast having this functionality.  This is a 
> major problem with IP multicast, as some sort of address selection 
> arbitration has to be done.  From what I've seen, this ranges from IANA 
> assigning multicast addresses for specific uses to best-effort protocols 
> for selecting unused addresses from an available range.  It's a fairly 
> hard problem, and having OFED choose an unused address (my understanding 
> is that the SM is capable of this) sidesteps the issue and makes life 
> much better.

This is an IB specific feature that could be exposed through the rdma_cm.  I can 
envision other RDMA transports providing a similar capability, even if it 
requires some sort of proprietary method.

- Sean