Self-Protecting Multi-Paths - A Simple and Efficient Protection Switching Mechanism

Michael Menth (Universität Würzburg)


In this talk we propose the concept of an end-to-end (e2e) Self-Protecting Multi-Path (SPM) as a protection switching mechanism that may be implemented, e.g., in Multiprotocol Label Switching (MPLS) networks. In case of local outages, resilient networks redirect the traffic from a failed link over an e2e backup path to its destination. In this case, Quality of Service (QoS) can only be provided if sufficient extra capacity is available. If backup capacity can be shared among different backup paths, multi-path routing allows for considerable savings regarding this extra capacity. The SPM consists of disjoint paths that carry the traffic both in normal operation mode and during local outages. If a partial path is affected by a network failure, the traffic is just distributed to the remaining working paths. This structure is easy to configure and the switching to failure mode operation is simple since no signalling is required. Based on analytical results, we show that load balancing of the traffic across the disjoint paths can reduce the required backup capacity significantly. The backup performance depends strongly on the network topology, and the SPM outperforms simple Open Shortest Path First (OSPF) rerouting by far.