Voice over Internet Protocol (VoIP) applications are making their way into safety-critical environments. If voice data has to be transmitted in such environments, the connection must not fail and the network has to recover quickly. Additionally, the use of specialized systems that are tailored to a certain application is not a preferred solution. Instead, the use of commercial-off-the-shelf (COTS) hard-and software is required. This paper discusses the use of standardized hard-and software as well as network protocols to allow failover times within the range of milliseconds. A redundant end-system and its network coupling are presented. The Layer 3 protocol OSPF and the combination of OSPF with the protocol-independent Hello protocol BFD are investigated to fulfill the requirements. The tests and the achieved results show a significant reduction of the convergence time.
Abstract. During the last decade communication technology has changed rapidly. Due to its decreasing costs and rising expansion, IP (Internet Protocol) technology has found its way to areas that have long been the domain of publicswitched telephone networks (PSTN). Voice over IP (VoIP) applications are widely used not only for phone calls or common Internet conferences, but also tend to be used for safety critical communication applications. Hence security and safety topics arise, which pose new challenges in this area of research. The authors are convinced that new issues on the network layer as well as on the application layer require detailed analysis. Hence this paper gives an overview on latest developments in this area, and states the authors' view on this topic. Thereby safety and security issues are faced from different abstraction layers. On the one hand the network layer and on the other hand the application layer focusing on middleware systems in the area of service oriented architectures (SOAs).
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