[HECnet] Multinet protocol description

[Dennis Boone]

Yes, I saw the DECnet/Linux code.   It's rather puzzling because it seems
to tie into a tun/tap device -- so it expects Ethernet behavior.   But
then it converts to short headers, which suggests point to point
behavior.   Which is it?   The data headers are only a tiny part of the
difference between the two datalink flavors...

If I understood it correctly when I looked at it a while back, Multinet
uses the DECNET point-to-point frame format in the UDP packets it
exchanges with the remote.   But Linux DECNET is unlikely to have any
real hardware point-to-point links, and quite reasonably expects any
frames from the local LAN (including those on e.g. a Linux virtual
bridge from a simh instance running locally) to be in the broadcast
format used by DECNET if its interface is an ethernet.   Linux DECNET
therefore converts between the two formats as necessary.

Once I got past that, I was able to follow what was going on in packet
captures based on how the Linux multinet program shuffled around array
elements.

De