  Convergence of time-sensitive machine control networks as part of the
operational technology (OT) with the ubiquitous information technology (IT)
networks is an essential requirement for the ongoing digitalization of
production. In this paper, we review the fundamental differences between both
technologies, the challenges to be solved, existing and upcoming solutions like
TSN and their limitations. Furthermore, we introduce an Ethernet extension for
a backbone network at factory scale and line rates of 10 - 100Gbit/s. The
backbone is intended to carry massive amounts of IT traffic together with the
traffic of multiple independent OT networks at the precision of leading-edge
field bus technologies in the sub-microsecond range. The backbone remains
transparent and does not require changes to the attached OT sub-networks. We
prove our claims by prototype measurements, interoperability tests and field
trials.
