COINC library: a toolbox for the network calculus

2016 IEEE 24th International Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS), 2016

Messages traversing a network commonly experience waiting times due to sharing the forwarding resources. During those times, the crossed systems must provide sufficient buffer space for queueing messages. Network Calculus (NC) is a mathematical methodology for bounding flow delays and system buffer requirements. The accuracy of these performance bounds depends mainly on two factors: the principles manifesting in the NC flow equation and the functions describing the system. We focus on the latter aspect. Common implementations of NC overapproximate these functions in order to keep the analysis computationally feasible. However, overapproximation often results in a loss of accuracy of the performance bounds. In this paper, we make such compromising tradeoffs between model accuracy and computational effort obsolete. We limit the accurate system description to functions of a compact domain, such that the accuracy of the NC analysis is preserved. Tying the domain bound to the algebraic operators of NC instead of the operational semantics of components, allows us to directly apply our solution to algebraic NC analyses that implement principles such as pay burst only once and pay multiplexing only once.

2018

The convolution operation used in deterministic network calculus differs from its counterpart known from the classic systems theory. A reason for this lies in the fact that the former is defined in terms of the so-called min-plus algebra. Therefore, it is oft difficult to realize how it really works. In these cases, its graphical interpretation can be very helpful. This paper is devoted to a topic of construction of the min-plus convolution curve. This is done here in a systematic way to avoid arriving at non-transparent figures that are presented in publications. Contrary to this, our procedure is very transparent and removes shortcomings of constructions known in the literature. Some examples illustrate its usefulness.

IEEE Access

Network Calculus is an established analytical framework which can provide deterministic estimates of latency and buffer requirements for feed-forward packet-switched communication networks. Researchers find it useful in analyzing network performance in real-time systems. As there are several Network Calculus tools and software packages for estimating network performance, it is important to select suitable Network Calculus tools for network analysis problems. This article introduces twelve established tools for Network Calculus analysis and compares their advantages and disadvantages in terms of their applicability for various systems and analysis needs. We also provide recommendations for users to select the suitable tools for research. Five public tools, namely DiscoDNC, RTC Toolbox, Deborah, CyNC, and nc-tandem-tight, are chosen to analyze end-to-end delay in a series of tandem networks for their performance demonstration. Simulations of the same tandem networks are implemented to compare with the analytical results achieved by the Network Calculus tools. To our best knowledge, this is the first comprehensive study that compares existing tools of Network Calculus analysis for real-time system network infrastructure. Our aim is to provide quick guidance to research communities for selecting suitable tools to analyze delay performance of networks. INDEX TERMS Network calculus, DiscoDNC, RTC toolbox, nc-tandem-tight, deborah, CyNC, real-time systems.

IEEE Transactions on Circuits and Systems, 1977

Lecture Notes in Computer Science, 2013

2006 8th International Workshop on Discrete Event Systems, 2006

Discrete Event Dynamic Systems (DEDS) are systems whose state transitions are triggered by events that occur at discrete instants of time. The communication networks are examples of this kind of systems. The mathematical constraints of some DEDS can be described more adequately using the Max-Plus algebra. Previous works show that the problem of determining performance bounds for communication networks is simplified if modeled using this algebra. The compilation of existing rules and results on this field is called Network Calculus. The goal of this article is to improve a systematic use of the Max-Plus algebra in the formulation and derivation of results on Network Calculus. To illustrate the introduced methodology, we analyze a window flow controller, a system that controls the traffic admitted by a network in order to limit its backlog in a specified manner.

2008

Recent advances in network theory have led to considerable progress in our understanding of complex real world systems and their behavior in response to external threats or fluctuations. Much of this research has been invigorated by demonstration of the 'robust, yet fragile' nature of cellular and large-scale systems transcending biology, sociology, and ecology, through application of the network theory to diverse interactions observed in nature such as plant-pollinator, seeddispersal agent and host-parasite relationships. In this work, we report the development of NEXCADE, an automated and interactive program for inducing disturbances into complex systems defined by networks, focusing on the changes in global network topology and connectivity as a function of the perturbation. NEXCADE uses a graph theoretical approach to simulate perturbations in a user-defined manner, singly, in clusters, or sequentially. To demonstrate the promise it holds for broader adoption by the research community, we provide pre-simulated examples from diverse real-world networks including eukaryotic protein-protein interaction networks, fungal biochemical networks, a variety of ecological food webs in nature as well as social networks. NEXCADE not only enables network visualization at every step of the targeted attacks, but also allows risk assessment, i.e. identification of nodes critical for the robustness of the system of interest, in order to devise and implement context-based strategies for restructuring a network, or to achieve resilience against link or node failures. Source code and license for the software, designed to work on a Linux-based operating system (OS) can be downloaded at http://www.nipgr.res.in/nexcade_download.html. In addition, we have developed NEXCADE as an OS-independent online web server freely available to the scientific community without any login requirement at http://www.nipgr.res.in/nexcade. html.

SIAM Journal on Matrix Analysis and Applications, 2021

We describe a complete theory for walk-based centrality indices in complex networks defined in terms of Mittag-Leffler functions. This overarching theory includes as special cases wellknown centrality measures like subgraph centrality and Katz centrality. The indices we introduce are parametrized by two numbers; by letting these vary, we show that Mittag-Leffler centralities interpolate between degree and eigenvector centrality, as well as between resolvent-based and exponential-based indices. We further discuss modelling and computational issues, and provide guidelines on parameter selection. The theory is then extended to the case of networks that evolve over time. Numerical experiments on synthetic and real-world networks are provided.

arXiv (Cornell University), 2016

In the article, we describe a new algebraic approach to the temporal network analysis based on the notion of temporal quantities. We define the semiring for computing the foremost journey and the traveling semirings for the analysis of temporal networks where the latency is given, the waiting times are arbitrary, and some other information on the links are known. We use the operations in the traveling semiring to compute a generalized temporal betweenness centrality of the nodes that corresponds to the importance of the nodes with respect to the ubiquitous foremost journeys in a temporal network.