Dynamic Repair and Robust Optimization of Complex Networks

Network repair is indispensable for maintaining network security. Conventional static repair is relatively inefficient. In this study, by considering the energy transfer between nodes, a dynamic repair model was established. The fundamental reason for the secondary failure of repaired nodes during the dynamic repair process is the coupling structure of failure networks. A dynamic repair strategy was proposed that can effectively prevent the secondary failure of repair nodes influenced by energy during repair and can cause the redundant capacity of repair nodes to be used reasonably. By turning off the energy transfer function of the link to control the excessive flow of energy into the repair node to avoid the occurrence of secondary failure; on the other hand, by sharing part of the load of the failure node, realize the rational use of the redundant capacity of the repair node to reduce the impact of the failure node on the overall function of the network. The proposed strategy mitigated the effect of failure nodes on network functions and substantially improved the recovery efficiency of network functions. Furthermore, redundant edges, behaving as energy redundant links in a network structure, can considerably improve the robustness of the network by optimizing the removal of redundant edges. Dynamic repair is not only an efficient repair method but also a highly flexible choice for network repair.

An Application-Level Method of Arbitrary Synchronization Failure Detection in TTEthernet Networks

Precise distributed clock synchronization is important for Time-Triggered Ethernet (TTEthernet) in which fail-arbitrary synchronization failure cannot be treated by existed protocols unless every synchronization node is equipped with a dedicated clock monitoring. A novel method was presented to detect arbitrary synchronization failure by some application-level routines which make distributed decisions mainly by monitoring the protocol control frames (PCFs). An arbitrary failure node can be exactly detected and located by the routine resided on each of the Compression Masters based on the concerned accusation messages sent from Synchronization Masters or Synchronization Clients. The proposed method can make up the weak points on the detection of the arbitrary failure node of the existed fault-tolerant synchronization mechanism and enhance the synchronization node to resist the arbitrary failure for TTEthernet. By our SAL-based model checking, this method had been formally verified to have a fail-arbitrary detection capacity even in a standard integration configuration. Simulations imply that the quality of the whole clock synchronization is effectively improved after the failure node has been isolated.

Fallback Based k-Hop Backtracking Trustworthy Rerouting Mechanism

When some links or nodes on the path break down, a rerouting path should be found in trustworthy network. In this paper, a fallback based k-hop backtracking trustworthy QoS (Quality of Service) rerouting mechanism is proposed. First,the network model and user trust evaluation model are constructed. Then the description of users requirements, the calculation methods of users satisfaction and the criterion of path judgments are presented. Considering users QoS requirements, trustworthy requirements and decrease of the algorithm cost, fallback is used for backtracking rerouting at the previous node of the failure node (or link) in the proposed mechanism. It reuses original links of the path as much as possible to reduce the time of rerouting. The simulation results show that the proposed mechanism is both feasible and effective. In contrast to existing mechanisms, both the rerouting success rate and user satisfaction degree are increased and the rerouting time is reduced under uses requirements.