Transformative Network Engineering
The overall functionality provided by a distributed system often requires rapid and reliable deterministic communication between distributed devices and precise synchronisation between networked nodes. The research work carried out by the InES in this area encompasses the development, optimisation and verification of both internationally standardised protocols and application- and client-specific systems.
Redundancy protocols are used in order to improve the availability of a network.
Such protocols typically perform a reconfiguration of the network after a failure of a node or a link, i.e. a new network topology is computed and activated. Applications cannot communicate during this reconfiguration for some 100 ms up to a few seconds, depending on the type of protocol and on size of the network. Demanding applications in the field of automation, transportation, and power distribution require mechanisms free of interruption, i.e. qualified as “with zero switchover time” or “bumpless”.
An approach to realize bumpless redundancy is to transmit multiple copies of a frame over different independent paths at the same time. The receiver processes the copy arriving first and discards the duplicates. The “High-availability Seamless Redundancy” (HSR) Protocol implements – similarly as the Parallel Redundancy Protocol (PRP) – this strategy, but in a ring. A ring provides for each communication association two disjoint paths.