[openib-general] Multicast address aliasing in IPoIB

[Hal Rosenstock]

On Thu, 2004-09-09 at 22:43, Roland Dreier wrote:
> I see no reason to modify the IPoIB multicast mapping just because the
> Linux kernel does not yet have support for it.  

Agreed.

> For newer kernels, there is no reason that the IPoIB driver has to
> masquerade at an ethernet driver -- we should be aiming for a fully
> native driver that sets its dev->type field to ARPHRD_INFINIBAND.

Hopefully we are moving to this if not already there.

> Once the OpenIB IPoIB driver is ready to be merged upstream, it should
> be no problem to get the trivial changes required in the core
> networking code merged.  As far as I can tell, the only changes needed
> would be: implement an ip_ib_mc_map() function and add
> 
> 	case ARPHRD_INFINIBAND:
> 		ip_ib_mc_map(addr, haddr);
> 		return 0;
> 
> to arp_mc_map() in net/ipv4/arp.c and to make the analogous addition
> for ndisc_mc_map() in net/ipv6/ndisc.c.  (ARPHRD_INFINIBAND is already
> defined in the Linux headers -- I got that merged back in early 2003)

The only issue I see is where the scope and PKey would come from to 
form the MGID. The scope could default to link local (2). I would
presume the PKey would come from the IPoIB interface somehow.

-- Hal