Rony Haim Ohayon

A fuzzy-based path ordering algorithm for QoS routing in non-deterministic communication networks

We present a novel, fuzzy-based method for path selection under additive quality of service constraints, where the information available for making routing decisions is inaccurate. The goal of the path selection process is to identify a feasible path while minimizing the overall setup time required for establishing a successful connection. Under the assumption that a list of candidate paths already exists, we explore the fuzzy logic approach for this purpose. The performance evaluation of the proposed algorithm is done by a simulation program that compares between the fuzzy logic approach, the optimal solution and a standard approach suggested in the literature, where the main performance metric is the average setup time for successfully establishing a feasible connection. The results show that the fuzzy approach has a lower average setup time for establishing a connection than the standard approach and that it is almost as efficient as the optimal solution.

Placement of network resources in communication networks

Data communication and telecommunication networks consist of nodes, links and network resources. Many studies have dealt with the design of optimal network topologies. In current methodologies, every node presents the same constraints and behavior, however, in reality, the network resources vary. The research problem at stake here is how to add central network resources (i.e., servers, gateways, network managers, probes, mainframes, etc.) in an optimal way. For small networks or for a small number of resources, it is feasible to solve the problem by checking all the possibilities of locating the resources and choosing the optimal location. However, this method cannot be applied for large networks, where a great many of resources are located. In such cases, we confront a difficult optimization problem that is classified as NPcomplete. In this study we deal with optimal and heuristics techniques in order to solve this kind of problem.

Fuzzy based paths ordering algorithm in networks with imperfect QoS information

In this paper, we study the problem of path selection under additive QoS (quality of service) constraints, where the information available for making routing decisions is inaccurate. The goal of the path selection process is to identify a feasible path while minimizing the overall setup time required for establishing a successful connection. Under the assumption that a list of candidate paths already exists, we explore the fuzzy logic approach to minimize the overall setup time by finding an optimal preference order of the given paths. A simulation program was used to evaluate the performance of the proposed algorithm. In the simulation, we compare between the fuzzy logic approach and another approach suggested in the literature to solve a similar problem, where the main performance metric is the average setup time for successfully establishing a feasible connection. The results show that the fuzzy approach has a lower average setup time for establishing a connection than the existing approach.

Network resources location

There are many studies dealing with the design of optimal communication network topologies. However, in the current methodologies, every user or node presents the same constrains and behavior, while in reality networks resources have different characteristics than any other user or node. The greedy algorithm is offered for locating-central network resources on a communication network. The algorithm is generic and can be applied to various LANs and WANs. The proposed method gives the network manager analytical tools to deal with the issue of how to locate central resources in networks. The algorithm was compared to an optimal solution where possible, to lower bound, and to the results of simulated annealing.

Algorithms for locating resources in a communication network

Both data communication and telecommunication networks consist of nodes, links and network resources. Many studies deal with the design of optimal network topologies. In current methodologies, every node presents the same constraints and behavior, while in reality, the network resources vary. The research problem at stake is how to add central network resources (i.e., servers, gateways, network managers, probes, mainframes, etc.) in an optimal way, for example, such that the transmission delay will be minimized. For small networks or for a small number of resources, it is feasible to find the optimal locations of the resources by checking all the possibilities. This method cannot be applied to large networks, where a great many of resources are located. In such cases the problem turns into a difficult optimization problem that can be classified as NP-complete. We deal with both optimal and heuristics techniques to solve this problem.