Gyula Sallai

Optimizing QoS aware Ethernet spanning trees

Ethernet is gaining in importance in both access and metro networks. As a layer 2 technology, Ethernet gives a basic framework for routing, QoS and traffic engineering (TE), as well as a protocol for building up trees. IEEE 802.1 standards define default configuration parameters considering the topology only. We propose methods for resource management in Ethernet networks through spanning tree optimization for both STP (spanning-tree protocol) (IEEE 802.1D) and MSTP (multiple spanning-tree protocol) (IEEE 802.1s). As a result of optimization, we assign costs to the bridge ports in the network to build trees based on these costs via STP and MSTP. These trees yield optimized routing, TE and support for different QoS classes. We show on typical metro-access networks that, through optimization, the total network throughput can be significantly increased for both enforcing fairness or allowing starvation of some demands. This gain can be realized by simultaneously assigning demands to trees and routing these trees.

Migrating to IPv6: A game-theoretic perspective

The rate of deployment and adoption issues of new network technologies, IPv6 in particular, have recently been hotly debated in the research community. However, the question of how protocols migrate, especially the dynamics of migration, to new paradigms is still largely open. In this paper, we address the issue from a game theoretic point of view. We model and analyze the profit maximizing strategies of Autonomous Systems (ASes); both the properties of ASes and the topology of the Internet is considered. The contribution of our work is threefold. First, we propose an economic model of the ASes and their relations from the IPv4-IPv6 migration viewpoint. Second, we apply the findings of evolutionary dynamics on the problem of migration by incorporating Internet-specific properties to the evolutionary model, namely the size of the ASes and the cost of migration. The analyses show that even if IPv6 has higher payoff than IPv4, the whole migration does not happen always fast. Finally, extensive simulations are carried out based on the proposed models to illustrate the impacts of different parameters on the IPv6 migration dynamics in realistic scenarios.

Route Planning with Uncertain Information using Dempster-Shafer theory

The aim of this paper is to find a solution for route planning in a road network, where the costs of roads are uncertain. Our concept is based on the Dempster-Shafer theory and Dijkstras algorithm, which helps to find the best routes. We model the influencing factors of the traffic congestion on the roads using uncertain probabilities described by probability intervals. Based on these intervals the cost intervals of each road can be calculated. Taking the uncertain values of costs into account an algorithm has been outlined for determination the best routes from a node to all other nodes comparing the cost intervals and using decision rules. Decision rules can be defined by the end user, if necessary node by node.

From telecommunications to cognitive infocommunications and internet of things - Phases of digital convergence

The widespread deployment of mobile communications and the Internet in the 1990s accelerated a convergence process based on common digital technology. Telecommunications and the Internet are increasingly forming an integrated system for processing, storing, accessing and distributing information and managing content. Recently the content space is expanding by cognitive and sensory contents, media convergence is highlighted and Internet architectures are reconsidered. Integrated Telecom IT/Internet Media (TIM) systems are relevant part of the Digital Ecosystems, such a way, of the Intelligent Engineering Systems.

Shared protection of demands with Physical Impairment Constrained Routing

The difference between dedicated and shared protection is well known. In this paper we investigate these ideas applied to sharing power budgets of links. When defining protection paths not as a “hot stand-by” but rather as a “cold stand-by” the power needed for protection will be lower; therefore the routeable distance of certain connections should be longer, that increases the number of routeable demands. In this paper we present simulation results to show that in reality with the introduction of shared protection for Physical Impairment Constrained Routing (PICR) in large or saturated networks the number of routeable demands is lowered.

Network Resilience Requirements and Algorithms for Multicasting and Broadcasting Digital TV

In this paper we give an overview of the network architecture and of the resilience requirements for both, metro and core networks.

Understanding the impact of loyal user behaviour on Internet access pricing: a game-theoretic framework

In this paper, we investigate the impacts of user behaviour—user loyalty in particular—on pricing strategies of Internet Service Providers (ISPs) for a profitable yet sustainable Internet access marketplace. We carry out an extensive empirical analysis of customer loyalty issues of ISP markets including our own survey in the Hungarian ISP market. Based on the empirical results, we propose a realistic user loyalty model, the price difference dependent loyalty model. Next, we apply the loyalty model in game-theoretical framework where optimal Internet access pricing strategies are expressed. Our game-theoretic framework includes both short-term and long-term interaction cases (single-shot and repeated games, respectively) and is capable of dealing with uncertain as well as dynamic scenarios (Bayesian and Stackelberg games, respectively). Finally, we present the impacts of user loyalty on the prices and profits of ISPs in different scenarios based on simulation results.

SRLG-Disjoint Multi-Path Protection: When LP meets ILP

Multi-Path Routing routes the upcoming demand over multiple paths. This is feasible in networks where the demand can be split into multiple parallel flows, i.e., the network is capable to perform inverse multiplexing (e.g., ngSDH and OTN via VCat) and where the connectivity of the topology also allows it.

Architecture and configuration of broadband access networks supporting multimedia applications

Recent Internet access speeds have made it possible even for home users to reach and use previously unavailable bandwidth consuming (e.g. video on demand) services. However, the rapid spread of these applications is hindered by the lack of QoS guarantees in packet networks. In this article a QoS architecture is presented which have been designed for access networks and applies a logical overlay network to make network management tasks easier. The novelty of the architecture lies in the application of two key procedures adopted for dimensioning logical channels between edge nodes and mapping them to the physical routes. The upper load thresholds of the applied logical channels are also determined, which may form the basis of a more sophisticated call admission control policy.

Towards Evaluating Size Reduction Techniques for Software Model Checking

Formal verification techniques are widely used for detecting design flaws in software systems. Formal verification can be done by transforming an already implemented source code to a formal model and attempting to prove certain properties of the model (e.g. that no erroneous state can occur during execution). Unfortunately, transformations from source code to a formal model often yield large and complex models, making the verification process inefficient and costly. In order to reduce the size of the resulting model, optimization transformations can be used. Such optimizations include common algorithms known from compiler design and different program slicing techniques. Our paper describes a framework for transforming C programs to a formal model, enhanced by various optimizations for size reduction. We evaluate and compare several optimization algorithms regarding their effect on the size of the model and the efficiency of the verification. Results show that different optimizations are more suitable for certain models, justifying the need for a framework that includes several algorithms.