[openib-general] IPv6oIB neighbour discover broken when MCGs overflow

[Roland Dreier]

 > For starters, I think that rate, MTU, and SL (and maybe PKey too) need
 > to be the same. There may be others too if I stare at the spec for a
 > while...

Can you expand on why?  For example I definitely can send to the same
MLID with different SLs.  Of course MTU and rate need to match up but
I don't see that as a real restriction -- the SM needs to allows for
least-common-denominator values anyway, since the least-capable node
on the fabric might join an existing group.

I don't see why one MCG with an MTU of 2048 and one MCG with an MTU of
1024 can't share the same MLID, as long as the underlying fabric is
capable of supporting an MTU of 2048.  Actually, I wonder what the
spec says about what switches should do if they're asked to forward
packets with too-big MTUs?  Maybe it all works out anyway.

 - R.