>     How do you deal with "multiple interfaces attached to the same
 > layer 3 network" routing problem?

    Oh, I see.  Just don't tell routing about it.  This makes life
much simpler than how I was proceeding was going.

    So I suppose this changes my focus; I haven't gotten to fiddling
with ethernet receivers yet.  I'll play with slashing up something
between the ethernet interface drivers and the ethersubr layer.  If I
come up with anything, I'll say something here.