539 research outputs found
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A survey on online monitoring approaches of computer-based systems
This report surveys forms of online data collection that are in current use (as well as being the subject of research to adapt them to changing technology and demands), and can be used as inputs to assessment of dependability and resilience, although they are not primarily meant for this use
Software Defined Networks based Smart Grid Communication: A Comprehensive Survey
The current power grid is no longer a feasible solution due to
ever-increasing user demand of electricity, old infrastructure, and reliability
issues and thus require transformation to a better grid a.k.a., smart grid
(SG). The key features that distinguish SG from the conventional electrical
power grid are its capability to perform two-way communication, demand side
management, and real time pricing. Despite all these advantages that SG will
bring, there are certain issues which are specific to SG communication system.
For instance, network management of current SG systems is complex, time
consuming, and done manually. Moreover, SG communication (SGC) system is built
on different vendor specific devices and protocols. Therefore, the current SG
systems are not protocol independent, thus leading to interoperability issue.
Software defined network (SDN) has been proposed to monitor and manage the
communication networks globally. This article serves as a comprehensive survey
on SDN-based SGC. In this article, we first discuss taxonomy of advantages of
SDNbased SGC.We then discuss SDN-based SGC architectures, along with case
studies. Our article provides an in-depth discussion on routing schemes for
SDN-based SGC. We also provide detailed survey of security and privacy schemes
applied to SDN-based SGC. We furthermore present challenges, open issues, and
future research directions related to SDN-based SGC.Comment: Accepte
Algorithms for Computing QoS Paths With Restoration
There is a growing interest among service providers to offer new services with Quality of Service (QoS) guarantees that are also resilient to failures. Supporting QoS connections requires the existence of a routing mechanism, that computes the QoS paths, i.e., paths that satisfy QoS constraints (e.g., delay or bandwidth).
Resilience to failures, on the other hand, is achieved by providing, for each primary QoS path, a set of alternative QoS paths used upon a failure of either a link or a node. The above objectives, coupled with the need to minimize the global use of network resources, imply that the cost of both the primary path and the restoration
topology should be a major consideration of the routing process.
We undertake a comprehensive study of problems related to
finding suitable restoration topologies for QoS paths. We consider both bottleneck QoS constraints, such as bandwidth, and additive QoS constraints, such as delay and jitter. This is the first study to provide a rigorous solution, with proven guarantees, to the combined problem of computing QoS paths with restoration. It
turns out that the widely used approach of disjoint primary and restoration paths is not an optimal strategy. Hence, the proposed algorithms construct a restoration topology, i.e., a set of bridges, each bridge protecting a portion of the primary QoS path. This approach guarantees to find a restoration topology with low cost when one exists
Managing Industrial Communication Delays with Software-Defined Networking
Recent technological advances have fostered the development of complex
industrial cyber-physical systems which demand real-time communication with
delay guarantees. The consequences of delay requirement violation in such
systems may become increasingly severe. In this paper, we propose a
contract-based fault-resilient methodology which aims at managing the
communication delays of real-time flows in industries. With this objective, we
present a light-weight mechanism to estimate end-to-end delay in the network in
which the clocks of the switches are not synchronized. The mechanism aims at
providing high level of accuracy with lower communication overhead. We then
propose a contract-based framework using software-defined networking where the
components are associated with delay contracts and a resilience manager. The
proposed resilience management framework contains: (1) contracts which state
guarantees about components behaviors, (2) observers which are responsible to
detect contract failure (fault), (3) monitors to detect events such as run-time
changes in the delay requirements and link failure, (4) control logic to take
suitable decisions based on the type of the fault, (5) resilience manager to
decide response strategies containing the best course of action as per the
control logic decision. Finally, we present a delay-aware path finding
algorithm which is used to route/reroute the real-time flows to provide
resiliency in the case of faults and, to adapt to the changes in the network
state. Performance of the proposed framework is evaluated with the Ryu SDN
controller and Mininet network emulator
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