Using the probabilistic evaluation tool for the analytical solution of large Markov models

Stochastic Petri net-based Markov modeling is a potentially very powerful and generic approach for evaluating the performance and dependability of many different systems, such as computer systems, communication networks, manufacturing systems, etc. As a consequence of their general applicability, SPN-based Markov models form the basic solution approach for several software packages that have been developed for the analytic solution of performance and dependability models. In these tools, stochastic Petri nets are used to conveniently specify complicated models, after which an automatic mapping can be carried out to an underlying Markov reward model. Subsequently, this Markov reward model is solved by specialized solution algorithms, appropriately selected for the measure of interest. One of the major aspects that hampers the use of SPN-based Markov models for the analytic solution of performance and dependability results is the size of the state space. Although typically models of up to a few hundred thousand states can conveniently be solved on modern-day work-stations, often even larger models are required to represent all the desired detail of the system. Our tool PET (probabilistic evaluation tool) circumvents problems of large state spaces when the desired performance and dependability measure are transient measures. It does so by an approach named probabilistic evaluatio

Performance of a connectionless protocol over ATM

Recent studies show the existence of a demand for a connectionless broadband service. In order to cope with this demand, a connectionless protocol for the B-ISDN needs to be designed. Such a protocol should make use of ATM and the ATM Adaptation Layer. It needs to specify destination and bandwidth of connections to the ATM network without advance knowledge of the traffic that has to be transferred over these connection. A possible mechanism which can cope with this problem, the 'On-demand Connection with Delayed Release' (OCDR) mechanism, is described. Its eficient operation is based on the assumption that there exists a certain correlation between subsequently arriving CL packets. Two different arrival processes are used to evaluate the performance of the OCDR mechanism: a Poisson arrival process, and a Markov Modulated Poisson Process (MMPP) which models a bursty trafic source. Markov models of the OCDR mechanism have been constructed for both arrival processes. For the madel with Poisson arrivals, a closed form solution is presented. The model with MMPP arrivals is solved numerically.\ud Compared to a 'Permanent Connection' mechanism significant bandwidth reductions can be obtained provided that the offered trafic has a bursty nature. Furthermore, the OCDR mechanism has the advantageous property that the obtained average node delay is not strongly related to the intensity and burstiness of the offered trafic

A method for analyzing the performance aspects of the fault-tolerance mechanisms in FDDI

The ability of error recovery mechanisms to make the Fiber Distributed Data Interface (FDDI) satisfy real-time performance constraints in the presence of errors is analyzed. A complicating factor in these analyses is the rarity of the error occurrences, which makes direct simulation unattractive. Therefore, a fast simulation technique, called injection simulation, which makes it possible to analyze the performance of FDDI, including its fault tolerance behavior, was developed. The implementation of injection simulation for polling models of FDDI is discussed, along with simulation result

NFC Payment Spy : a privacy attack on contactless payments

In a contactless transaction, when more than one card is presented to the payment terminal’s field, the terminal does not know which card to choose to proceed with the transaction. This situation is called card collision. EMV (which is the primary standard for smart card payments) specifies that the reader should not proceed when it detects a card collision and that instead it should notify the payer. In comparison, the ISO/IEC 14443 standard specifies that the reader should choose one card based on comparing the UIDs of the cards detected in the field. However, our observations show that the implementation of contactless readers in practice does not follow EMV’s card collision algorithm, nor does it match the card collision procedure specified in ISO

XMGM: performance modeling using matrix geometric techniques

Over the last two decades a considerable amount of effort has been put in the development and application of matrix geometric techniques for the analysis of queueing systems of which the (embedded) Markov chain exhibits a regular structure. Most of this work however has been presented in either a mathematical context or an a purely application-oriented context. In this paper we present XMGM, a performance analysis tool which allows its users to easily specify queueing systems in terms of interarrival and service time distributions. XMGM then takes care of the translation of this description to an underlying Markov chain that exhibits a matrix geometric solution. Subsequently, it takes care of the derivation of the measures specified by the user. With XMGM models are specified via C procedure calls. This turns out to be a very flexible approach for modelling queueing systems; it also allows for the easy evaluation of models over parameter range