Real-Time Fault-Tolerant Routing in High-Availability Multicast-Aware Video Networks
Live-videostream networks based on multimedia switches are the most recent products used in television production and distribution facilities to transport the live signal from sources like cameras or microphones to dedicated sinks like video monitors, loudspeakers and transmission lines. To switch signals from a single source to several destinations multicasting or point-to-multipoint technology is considered. To compute multicast trees for multimedia communication, constrained shortest paths algorithms are needed. They are fundamental to important network functionality such as Quality of Service (QoS) routing or Multiprotocol label switching (MPLS) path selection and the problems they attempt to solve are known to be NP-complete. In previous work, we have introduced a heuristic called Multimedia Multicast algorithm (MulMic), which delivers nearly optimal multicast trees in a short time. Here, we propose the combination of MulMic and two models for fault-tolerant routing: disjoint paths and reservation of backup paths. Furthermore we introduce a realtime algorithm we call ZirkumFlex to handle one or even several simultaneous node or line failures in a multicast network by a local search to bypass the failed node or line. We also apply our algorithm to example graphs to demonstrate its feasibility.
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