Nguyen Xuan Tien

A Novel Dual Separate Paths (DSP) Algorithm Providing Fault-Tolerant Communication for Wireless Sensor Networks

Fault tolerance has long been a major concern for sensor communications in fault-tolerant cyber physical systems (CPSs). Network failure problems often occur in wireless sensor networks (WSNs) due to various factors such as the insufficient power of sensor nodes, the dislocation of sensor nodes, the unstable state of wireless links, and unpredictable environmental interference. Fault tolerance is thus one of the key requirements for data communications in WSN applications. This paper proposes a novel path redundancy-based algorithm, called dual separate paths (DSP), that provides fault-tolerant communication with the improvement of the network traffic performance for WSN applications, such as fault-tolerant CPSs. The proposed DSP algorithm establishes two separate paths between a source and a destination in a network based on the network topology information. These paths are node-disjoint paths and have optimal path distances. Unicast frames are delivered from the source to the destination in the network through the dual paths, providing fault-tolerant communication and reducing redundant unicast traffic for the network. The DSP algorithm can be applied to wired and wireless networks, such as WSNs, to provide seamless fault-tolerant communication for mission-critical and life-critical applications such as fault-tolerant CPSs. The analyzed and simulated results show that the DSP-based approach not only provides fault-tolerant communication, but also improves network traffic performance. For the case study in this paper, when the DSP algorithm was applied to high-availability seamless redundancy (HSR) networks, the proposed DSP-based approach reduced the network traffic by 80% to 88% compared with the standard HSR protocol, thus improving network traffic performance.

A novel ring-based dual paths approach for reducing redundant traffic in HSR networks

In this paper, we propose a novel dual paths-based approach, called ring-based dual paths (RDP), to significantly reduce redundant unicast traffic in high-availability seamless redundancy (HSR) networks. RDP establishes dual paths for forwarding unicast frames between nodes in HSR networks. Unlike existing dual paths-based approaches, such as dual virtual paths (DVP) that establish dual paths for each connection pair of HSR terminal nodes, RDP sets up dual paths for each connection pair of HSR rings. Therefore, RDP significantly reduces the number of established dual paths, which, in turn, reduces the overhead in discovering and establishing dual paths, as well as the memory space required to store these paths compared with the existing dual paths-based approaches. The performance of RDP has been analyzed, evaluated, and compared to that of the standard HSR protocol and the DVP approach. Various simulations were conducted to validate the traffic performance analysis. Analytical and simulation results showed that for the sample networks RDP reduced network unicast traffic by 80-88% compared with the standard HSR protocol, thus freeing up network bandwidth and improving network traffic performance.

A Novel Approach for Reducing HSR Unicast Traffic Using Pre-defined Dual Paths

High-availability seamless redundancy (HSR) is a redundancy protocol for Ethernet networks that provides zero recoery time in case of a network failure. The feature of HSR makes it suited for time-critical and mission-critical applications, such as substation automation systems and military applications. However, the standard HSR protocol excessively generates unnecessary unicast traffic by redundant frame copies. This unnecessary redundant traffic causes high bandwidth consumption, resulting in the degradation of network performance. In this paper, we introduce a novel approach called ring-based dual paths (RDP) to reduce unnecessary unicast traffic in HSR networks. The purpose of RDP is to establish dual paths for forwarding unicast frames between nodes in HSR networks. Unlike dual virtual paths (DVP) approach, which establishes dual paths for each connection pair of terminal nodes, RDP sets up dual paths for each connection pair of terminal rings. Therefore, RDP significantly reduces control overhead in discovering and establishing dual paths, as well as the memory space required to store these paths compared with the DVP approach. The performance of RDP has been analyzed, evaluated, and compared to that of standard HSR protocol and the DVP approach. Simulations were conducted to validate the traffic performance analysis. The analytical and simulation results showed that, for our sample network, RDP reduced network unicast traffic by about 78% compared with standard HSR protocol, thus freeing up network bandwidth and improving network traffic performance.

A Novel Seamless Redundancy Protocol for Ethernet

High availability is crucial for industrial Ethernet networks and Ethernet-based control systems, such as automation networks and substation automation systems. As standard Ethernet does not support fault tolerance capability, the high availability of Ethernet networks can be increased by using redundancy protocols. In this paper, we present a novel seamless redundancy protocol for Ethernet networks called the Redundancy Protocol for Ethernet (RPE). Our proposed RPE not only provides seamless communications with zero switchover time in case of failure, but it also supports any topologies. The RPE is transparent and compatible with standard Ethernet nodes. These features of the RPE make it very useful for time-critical and mission-critical systems, such as substation automation systems, automation networks, and other industrial Ethernet networks.

LPLB: A Novel Approach for Loop Prevention and Load Balancing in Ethernet Ring Networks

Ethernet networks using rapid spanning tree protocol (RSTP) to ensure a loop-free topology and provide redundant links as backup paths in case an active link has failed. However, when a failure occurs, RSTP requires a significant amount of reconfiguration time in order to find an alternative path. RSTP is also limited by the number of nodes in a ring network, and its performance degrades when the number of nodes increases. In this paper, we introduce a new approach, called loop prevention and load balancing (LPLB), which can be applied to Ethernet ring networks. If failure occurs, LPLB only requires a very short amount of time to switch to an alternative path and in most cases; LPLB needs zero recovery time for that switching. In addition, under most situations, no data frames are lost when a node switches to an alternative path. Unlike RSTP and the media redundancy protocol (MRP), LPLB also provides load balancing among network links that in turn improves the network performance and reduces the probability of bottleneck occurrence.

A novel traffic reduction technique for the redundancy protocol for Ethernet (RPE)

The redundancy protocol for Ethernet (RPE) has been developed to provide seamless redundancy for Ethernet networks. The RPE is suitable for Ethernet-based time-critical and mission-critical systems that require fault tolerance and high availability. However, the main drawback of the RPE is that it still generates redundant unicast traffic in Ethernet networks. In this paper, we propose an enhanced version of the RPE, called the enhanced RPE (eRPE), to reduce the redundant unicast traffic in Ethernet networks. The purpose of the eRPE is to establish dual paths for each connection pair of switches in Ethernet networks. To avoid a single point of failure, the dual paths have no common switch nodes between them. These paths are then used to forward the unicast frames in Ethernet networks (instead of flooding the frames as in the RPE). In this paper, the traffic performance of the eRPE is analyzed, evaluated, and compared to that of the RPE. Several simulations were conducted using the OMNeT++ simulator in order to validate the performance analysis. The analyzed and simulated results show that the eRPE significantly reduces network traffic compared to the RPE, thus saving a significant amount of network bandwidth as well as improving network traffic performance.