Some Ethernet-based industrial network protocols are extensions
of previous bus-based protocols. Although it is to
be expected that the lower network layers would differ, the
level of compatibility between the these protocols at higher
protocol layers differs from technology to technology. Some
technologies are fully compatible, while others offer limited
compatibility by means of compatible data object and models,
or application layer profiles. System designers should keep
in mind that further proxy or translator hardware might be
required to interface between Ethernet and bus networks at the
application layer. Unfortunately it is very difficult to predict
what level of compatibility future protocols with existing,
which is also a concern during network design.