But HECnet as a whole is not connected to this segment... 
  I thought the majority of it was...     There are a few people, like me, who
are using Multinet but only a few cases.   I thought pretty much everything
was bridged.
  [FWIW, Multinet tunnels a point-to-point DECnet link, essentially like a
DDCMP link, over UDP.   For that you really need to have a router at either
end to pass traffic for other machines on either LAN.]
Bob