David Laight <david%l8s.co.uk@localhost> writes: > On Fri, Feb 01, 2013 at 05:27:07PM -0600, David Young wrote: >> /* If broadcasting on a simplex interface, loopback a copy */ >> if ((m->m_flags & M_BCAST) && (ifp->if_flags & IFF_SIMPLEX)) >> mcopy = m_copy(m, 0, (int)M_COPYALL); > ... >> BTW, it makes me grimace to see the simplex-loopback handled in an L2 >> transmit routine... > > The 'should you receive your transmits as if someone else had sent > the packet' question - which is what I think IFF_SIMPLEX is about > is 'interesting'. > Not doing it used to stop some stuff working, doing it confused > other places - unfortunately I can't remember what! Yes, I think IFF_SIMPLEX is about this. Note that it is crtiical for multicast to work right.
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