Failure Recovery Protocol Research Articles

Development of a novel seismic acquisition system based on fully autonomous ocean bottom nodes

It is now established that ocean bottom node (OBN) surveys provide superior seismic data compared to traditional towed streamers, but deployment of the nodes is time-consuming and expensive. As an alternative, we are developing a novel seismic acquisition system that utilises a fleet of fully autonomous underwater vehicles (AUVs) as OBNs. The objective is to eliminate the reliance on remotely operated vehicles (ROVs) or ropes for deployment, making ocean bottom seismic acquisition significantly more efficient and cost-effective. To succeed, several criteria need to be met, including recording of good geophysical data, system affordability, low power consumption, units’ ability to act autonomously (e.g. steer, land, listen, re-position, surface) and to respond to remote commands (e.g. cease activity, return), a failure recovery protocol, automated deployment and retrieval, and system-wide communications. The ability to record good seismic data was assessed in October 2022, when we performed active-source seismic field trials in the UK. Five AUVs were deployed adjacent to commercial nodes (all units carried identical geophysical payloads) and a series of 2D lines were acquired at varying orientations. Analysis of the data confirmed that our units achieved satisfactory coupling with the seabed. The unit’s in-water capabilities were assessed during multiple field trials in 2022 and 2023, offshore UK and Australia. Tests consisted of simulating seismic acquisition cycle (flights, landings, take-offs and repositioning) where it was verified that missions were reliably executed, including landing within 10 m from pre-planned locations and recording good quality passive seismic data.

A Reconfigurable Multicast Routing Protocol for Mobile Ad-Hoc Networks

An infrastructure independent and self-organizing network where the mobile nodes are communicated with each other through wireless links is referred asMobile ad-hoc network. Amajor challenging task of mobile ad-hoc networks is Route maintenance due to some reasons such as frequent topological changes, packet collisions and bad channels which may cause some link breakages. Reconfigurable Virtual Backbone (RVB) construction and maintenance play a vital role, mainly in the multicast routing of mobile ad-hoc networks (MANETs). In this paper, the issues in providing a reconfigurable virtual backbone with the lower overhead are investigated and here we come up with a solution and propose a Reconfigurable Multicast Routing Protocol (RMRP) for constructing a virtual backbone and generating an alternate path during link failures. In comparison with the existing backbone and link recovery protocols like Backbone Group Model (BGM), Hierarchical Virtual Backbone Construction (HVBC) protocol and Local Link Failure Recovery (LLFR) protocol, the proposed protocol yields effective results in constructing a reconfigurable virtual backbone and generating an on-demand alternate path with the minimized overhead, increasing packet delivery ratio, throughput, minimizing delay of transmission, energy consumption, and with the improved routing performance significantly.

QuickSwap: A Lightweight Fast Recovery Protocol for Mesh-based P2P Live Streaming

In this paper, we propose a failure recovery protocol named QuickSwap for mesh-based P2P live streaming systems. Unlike the existing mCache-based failure recovery scheme, QuickSwap enables peers to quickly recover their live streaming quality from neighbor failures by exchanging and pre-processing of local streaming information. Our contributions in this work are two-fold. First, QuickSwap’s lightweight streaminginformation exchange protocol together with the proposed neighbor maintenance and streaming-quality estimation methods provide a significant performance edge over the conventional mCache-based failure recovery. Second, we have built a system model for our proposal and have evaluated QuickSwap’s performance under different system settings through simulation methodology. Our results reveal that at a small, affordable overhead cost, QuickSwap protocol can support fast recovery of live streaming quality with a nearly 100% failure recovery success rate and a fail-over time less than one second for an average of exponentially distributed peer lifetimes as low as 10 minutes.

Efficient and Reliable Application Layer Multicast for Flash Dissemination

To disseminate messages from a single source to a large number of targeted receivers, a natural approach is the tree-based application layer multicast (ALM). In time-constrained flash dissemination scenarios, e.g. earthquake early warning, where time is of the essence, the reliable extensions of the tree-based ALM using ack-based failure recovery protocols cannot support reliable dissemination in the timeframe needed. In this paper, we propose FaReCast which exploits path diversity, i.e., exploit the use of multiple data paths, to achieve fast and reliable data dissemination. First, we design a forest-based M2M (Multiple parents-To-Multiple children) ALM structure where every node has multiple children and multiple parents. The intuition is to enable lower dissemination latency through multiple children, while enabling higher reliability through multiple parents. In order to maintain the M2M ALM structure in a scalable and reliable manner, we develop a DHT-based Distributed Configuration Manager. Second, we design multidirectional multicasting algorithms that effectively utilize the multiple data paths in the M2M ALM structure. A key aspect of our reliable dissemination mechanism is that nodes, in addition to communicating the data to children, also selectively disseminate the data to parents and siblings. As compared to trees using traditional multicasting algorithm, we observe an 80 percent improvement in reliability under 20 percent of failed nodes with no significant increase in latency for over 99 percent of the nodes. Moreover, we notice that FaReCast can reduce the network overhead more than 50 percent by tuning the M2M structure, as compared to the other reliable ALM based disseminations.

Maintaining Path Stability with Node Failure in Mobile Ad Hoc Networks

As the demand for mobile ad hoc wireless network (MANET) applications grows, so does their use for many important services where reliability and stability of the communication paths are of great importance. Therefore, a MANET must be able to establish reliable communication channels which are protected by failure recovery protocols. One approach for existing failure recovery protocols is based on using backup paths, or multi-paths. This technique provides for more stable communication channels for wireless services, in particular for MANET applications. But work on such multi-path protocols has focused on stability in the presence of link failure for MANETs. In this paper, we extend such protocols to maintain connection stability in the presence of node failure. Our work is focused on protecting the route of mobile wireless communications in the presence of node failure in order to improve their use in MANETs applications by discovering efficient stable communication channels with longer lifetimes and increased number of packets delivered.

Fast spanning tree reconnection mechanism for resilient Metro Ethernet networks

The low cost, high transmission rate and ubiquity of current Ethernet lead to the possibility of bringing Ethernet into Metropolitan Area Networks (MANs). However, the traditional spanning tree based Ethernet protocol does not meet the requirement for MANs in terms of network resilience, despite the advancement of Ethernet standardization and commercialization. In this paper, we propose a fast spanning tree reconnection (FSTR) mechanism for Metro Ethernet networks to handle single link failure. Upon failure of a link on a spanning tree, a distributed failure recovery protocol is activated to reconnect the broken spanning tree using a reconnect-link. We present the details of the protocol, including failure notification and forwarding table reconfiguration procedures. The pre-configuration of the reconnect-links to reconnect each spanning tree is formulated as an integer linear programming (ILP) problem. We prove that the pre-configuration problem is NP-complete. We develop an efficient algorithm based on 2-edge connectivity augmentation that can achieve close approximation to the optimal solutions. The numerical results of FSTR mechanism on different network topologies show its features of efficiency and fast recovery.

LSP partial spatial-protection in MPLS over WDM optical networks

We consider Label Switched Path (LSP) protection for connections with various protection grade requirements in multi-protocol label switching (MPLS) over wavelength division multiplexing (WDM) optical networks. In full protection, bandwidth needs to be reserved for the backup LSP to protect the failure of any fiber along the primary LSP. In this paper, we study the problem of partial spatial-protection (PSP) where bandwidth is reserved for the backup LSP to protect the failure of a subset of fibers traversed by the primary LSP to satisfy the specified protection grade. We formulate the optimal LSP PSP problem as an ILP and identify three suboptimal problems. For each suboptimal problem, an exhaustive search algorithm and a heuristic are developed. We analyze the probability that a connection can be restored upon a fiber failure and find that it is higher than or equal to the protection grade specified. We also develop a failure recovery protocol which specifies recovery operations upon failure and determines whether a connection can be recovered if the failed fiber is one of its unprotected fibers. Through extensive simulation experiments, we demonstrated that the proposed LSP PSP algorithms perform better than shared LSP protection in blocking probability and resource efficiency.

Optical Path Protection with Fast Extra Path Preemption

Emerging GMPLS (Generalized Multi-Protocol Label Switching)-based photonic networks are expected to realize the dynamic allocation of network resources for a wide range of applications, such as carriers' backbone networks as well as enterprise core networks and GRID computing. To address diverse reliability requirements corresponding to different application needs, photonic networks have to support various optical path recovery schemes. Thus GMPLS standardization bodies have developed failure recovery protocols for 1+1 protection, 1:N protection and restoration, with support of extra traffic and shared use of back-up resources. Whereas the standardization efforts cover a full spectrum of recovery schemes, there have not been many reports on actual implementations of such functionalities, and none of them included extra traffic. This paper introduces an OXC (Optical Cross Connect) implementation of GMPLS's failure recovery functionalities supporting 1+1 protection, M:N protection and extra path. Here extra path is an extension of GMPLS protection's extra traffic which can partially reuse protected paths' back-up resources. Evaluation of the implementation confirms rapid recovery of protected traffic upon a failure, even when preemption of an extra path is involved. It is also shown that its preemption scheme can resolve the issue of the poor scalability of GMPLS-based preemption when multiple extra paths are pre-empted upon a failure.

Failure recovery for structured p2p networks: Protocol design and performance under churn

Measurement studies indicate a high rate of node dynamics in p2p systems. In this paper, we address the question of how high a rate of node dynamics can be supported by structured p2p networks. We confine our study to the hypercube routing scheme used by several structured p2p systems. To improve system robustness and facilitate failure recovery, we introduce the property of K-consistency, K ≥ 1, which generalizes consistency defined previously. (Consistency guarantees connectivity from any node to any other node.) We design and evaluate a failure recovery protocol based upon local information for K-consistent networks. The failure recovery protocol is then integrated with a join protocol that has been proved to construct K-consistent neighbor tables for concurrent joins. The integrated protocols were evaluated by a set of simulation experiments in which nodes joined a 2000-node network and nodes (both old and new) were randomly selected to fail concurrently over 10,000 s of simulated time. In each such experiment, we took a snapshot of neighbor tables in the network once every 50 s and evaluated connectivity and consistency measures over time as a function of the churn rate, timeout value in failure recovery, and K. We found our protocols to be effective, efficient, and stable for an average node lifetime as low as 8.3 min. Experiment results also show that the average routing delay of our protocols increases only slightly even when the churn rate is greatly increased.

Failure recovery for structured P2P networks

Measurement studies indicate a high rate of node dynamics in p2p systems. In this paper, we address the question of how high a rate of node dynamics can be supported by structured p2p networks. We confine our study to the hypercube routing scheme used by several structured p2p systems. To improve system robustness and facilitate failure recovery, we introduce the property of K- consistency , K ≥ 1, which generalizes consistency defined previously. (Consistency guarantees connectivity from any node to any other node.) We design and evaluate a failure recovery protocol based upon local information for K-consistent networks. The failure recovery protocol is then integrated with a join protocol that has been proved to construct K-consistent neighbor tables for concurrent joins. The integrated protocols were evaluated by a set of simulation experiments in which nodes joined a 2000-node network and nodes (both old and new) were randomly selected to fail concurrently over 10,000 seconds of simulated time. In each such "churn" experiment, we took a "snapshot" of neighbor tables in the network once every 50 seconds and evaluated connectivity and consistency measures over time as a function of the churn rate, timeout value in failure recovery, and K . Storage and communication overheads were also evaluated. We found our protocols to be effective, efficient, and stable for an average node lifetime as low as 8.3 minutes (the median lifetime measured for Napster and Gnutella was 60 minutes [10]).

A Dynamic Light-Weight Group Service

The virtual synchrony model for group communication is a powerful paradigm for building distributed applications. Implementations of virtual synchrony usually use failure detectors and failure recovery protocols. In applications that require a large number of groups, significant performance gains can be attained if these groups share the resources required to provide virtual synchrony. A service that maps multiple user groups onto a small number of instances of a virtually synchronous implementation is called a light-weight group service. This paper describes a new design for the light-weight group protocols that enables such service to function transparently. We discuss how these protocols can be applied in dynamic environments, where group mappings cannot be defined a priori and may change over time. We show that it is possible to establish mappings that promote resource sharing and, at the same time, minimize interference. These mappings can be established in an automated manner, using heuristics applied locally at each node. Experiments using an implementation in the Horus system show that significant performance improvements can be achieved with this approach.

An industrial application of modal process logic

Modal process logic is an extension of CCS that allows for more expressive specifications. We show how modal process logic was successfully applied in the development of a failure recovery protocol for an air-traffic information system now in service at Heathrow airport. Two example systems are used to show that CCS itself was not suitable for this application.