[openib-general] [PATCH] IPOIB: Use a GRH when appropriate for unicast packets

[Hal Rosenstock]

On Wed, 2007-02-07 at 16:31, Jason Gunthorpe wrote:
> On Wed, Feb 07, 2007 at 12:24:08PM -0800, Sean Hefty wrote:
> > >I didn't get too far on getting CMA to work. Beyond the bad HopLimit
> > >feild I was seeing Hal pointed out a number of problems in IBA that
> > >would prevent it from working as is :<
> > 
> > I've started thinking about what it would take to get the rdma cm to work 
> > across a router.  I think the rdma cm may need to treat IPv6 addresses as a 
> > GID for this to work across subnets, versus trying to map an ipoib IP 
> > address to a GID based on ARP.
> 
> I don't think that is the main problem - though clearly the way things
> are now (for better or worse) rdma cm requires the IPoIB subnet to
> span all of the IB subnets.. The main problem with the protocol is in
> the LID selection for routed paths on the passive side. It can't rely
> on the active side to identify the lids if a router is involved.
> 
> One feature I've thought has been underused in IBA is the raw IPv6
> packet feature.

I thought raw support (including IPv6 header) although still in the spec
was largely deprecated as the CRC protection was deemed too weak.

-- Hal

>  It would be nice to have a linux netdev interface to
> be able to do IPv6 traffic using GID addressing. That would seem to me
> to be the natural way to bolt native GID addressing into rdma
> cm..
> 
> Jason
> 
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