  Current designs of future In-Vehicle Networks (IVN) prepare for switched
Ethernet backbones, which can host advanced LAN technologies such as IEEE
Time-Sensitive Networking (TSN) and Software-Defined Networking (SDN). In this
paper, we present an integrated Time-Sensitive Software-Defined Networking
(TSSDN) architecture that simultaneously enables control of synchronous and
asynchronous real-time and best-effort communication for all IVN traffic
classes. Despite the central SDN controller, we can validate that control can
operate without a delay penalty for TSN traffic, provided protocols are
properly mapped. We demonstrate how TSSDN adaptably and reliably enhances
network security for in-vehicle communication. A systematic investigation of
the possible control flow integrations with switched Ether-networks reveals
that these strategies allow for shaping the attack surface of a
software-defined IVN. We discuss embeddings of control flow identifiers on
different layers, covering the range from a fully exposed mapping to deep
encapsulation. We experimentally evaluate these strategies in a production
vehicle, which we map to a modern Ethernet topology. Our findings indicate that
visibility of automotive control flows on lower network layers enables
isolation and access control throughout the network infrastructure. Such a
TSSDN backbone can establish and survey trust zones within the IVN and reduce
the attack surface of connected cars in various attack scenarios.
