Re: Port numbers in the network layer?

> On the other hand: Do you know a current technology which is actually
> being used that does not use Ethertypes?

CANbus, SpaceWire, CCSDS, RapidIO, (A)X.25...

But you can always  layer (Cisco) HDLC or HDLC/ Frame Relay across any
of these to get an Ethertype. Or lobby SpaceWire to put a value in
their single-byte not-an-Ethertype field.

(The CCSDS community finds the thought of layering HDLC over CCSDS
especially abhorrent, because it cuts down their custom engineering,
and any layering or modularity is considered to be inefficiency.)

Lloyd Wood
http://sat-net.com/L.Wood/