[ofa-general] Re: OpenSM IPv6 consolidation

[Ira Weiny]

On Thu, 29 May 2008 17:00:27 -0600
Jason Gunthorpe <jgunthorpe at obsidianresearch.com> wrote:

> On Thu, May 29, 2008 at 02:35:35PM -0700, Ira Weiny wrote:
>  
> > But that begs the question: Can a node issue an SNM request to a node in
> > another IB subnet?  (I think the answer is yes if the IP subnet spans more than
> > one IB subnet)  In that case, the SNM address would be in the range
> > ff02::1:ff00:0/104 but what MGID would that map onto in IB?  I think the
> > current mapping results in an IB link-local scope.  So would a router have to
> > forward it even though the IB scope is link-local?
> 
> IP (v4 and v6) 'link local' traffic (ie IPv4 broadcasts and IPv6 link
> local multicast) use MGID scope bits that are dependent on the
> configuration of the IPoIB stack. Today linux and everyone else uses
> link local MGID scope. There are patches floating about to make this
> configurable like pkey so that you can have a global IB scope IPoIB
> subnet. We used that patch set at SC07 to demonstrate IPoIB running
> single subnet across IB routers.
>

So, in that case if one is having issues with MLID space and wants to use my
hack it should consolidate all the scopes.

BTW, I still have on the back burner plans to implement a "real" fix to this
problem...  If only there were say -- 100 hours in a day?  ;-)

Ira