In this paper, we report on the results of performance measurements for an integrated B-ISDN/intelligent network signaling network. The specification, implementation and realization as well as the performance measurements are all part of a European project named INSIGNIA. The results reported in this paper pertain to the signaling system built in the second trial of the project and pertain to one of the demonstrated services: the interactive multimedia retrieval service. In the performance analysis, the results are presented with different 'perspectives', each serving a different purpose. For instance, the 'message processing' perspective which helps implementers to optimize the systems and provides parameter values for performance modeling. The 'service procedure' perspective takes a more service oriented view which helps in evaluating the service and gives a clear view of the contribution of each physical entity involved in the provisioning of the service.

The evolution of increasingly complex telecommunication services, has fuelled in the last years the development of new network architectures. There is a growing interest on the evolution of the intelligent network and of the B-ISDN. The integration of the signalling systems of these two architectures will allow, in a medium term scenario, the support sophisticated services. The provision of these services will entail, on the other hand, an increase of the signalling load on the network and in particular on the service control point, the network element which contains the intelligence to control the service provision. It is therefore necessary to introduce some congestion control mechanism in order to protect such node from overload situations. A performance study relevant to two congestion control mechanisms is presented. The study has been carried out by means of simulation; moreover, theoretical upper bounds for the throughput performance of the two mechanisms have been calculated.

The multiplexing of shaped on-off sources on an asynchronous transfer mode (ATM) link is addressed. In particular, an N-level shaper is analyzed. It modulates the source output bit rate on the basis of the buffer occupancy level. A very accurate analytical model describing its behavior is provided. Such a model allows an accurate description of the shaper output flow characteristics. A simple analytical model is also proposed for an ATM multiplexer in order to evaluate the advantages arising from the source shaping. The accuracy of the analytical results comes out from the comparison with the simulation ones. Numerical results show the effectiveness of the proposed shaping mechanism. They demonstrate that a substantial increase of the number of multiplexable sources is possible, for a given value of cell loss probability.>

This work deals with a general method for buffer design in an ATM system in which the target loss probability should be very low (e.g. less than 10/sup -9/). This method is based on the application of the generalized extreme value theory (GEVT) to results arising from simulation runs. This theory allows the estimation of very small probabilities which would not be evaluable with the traditional Monte Carlo approach. An advantage of 4/5 decades with respect to Monte Carlo limits can be obtained utilizing the same sample set. The extension of the theory to the case of distribution functions of discrete random variables is discussed. The applicability of the method is demonstrated with reference to known probability distribution functions. Moreover, the GEVT is applied in the cases of classical queuing systems. The general criteria for the evaluation of the basic GEVT parameters are discussed.>

A fully distributed routing control scheme, called the flooding technique, is described. It is to be applied to an ATM (asynchronous transfer mode) switch architecture for the establishment of CBO (continuous bit stream oriented) calls. The main advantage of this technique with respect to a centralized solution consists of a sensitive improvement of the system performance, particularly in fault-tolerance and flexibility. Two service scenarios are considered: CBO services characterized by a burstiness equal to one, and by a burstiness greater than one. The implementation alternatives of the flooding technique relevant to both the scenarios are presented, and their main characteristics are compared. The ATM switch architecture and its mode of operation are also described. In particular, the different strategies for handling CBO and nonisochronous classes of traffic are presented, and some properties on the topology of the switching fabric are given.>

The nonblocking properties of the generalized parallel delta networks (GPDNs) and their application to the photonic switching environment are discussed. It is demonstrated that the crosstalk due to the switch crossover can be completely avoided by means of a proper dimensioning of the network parameters. A classification of the nonblocking properties is proposed. In particular, a nonblocking condition, called as strong, is defined. It establishes that two paths are not in conflict if they do not share any switching element. The strong nonblocking condition has been considered together with the traditional one. This second condition, called as weak because it is based on the unshareability of the interstage links, is normally applied in the electronic environment. The conditions which have to be satisfied so that a GPDN can be weakly and/or strongly nonblocking are found and demonstrated.>

The definition is presented of a class of N*N multistage interconnection networks called generalized parallel delta networks (GPDNs). This class includes the already known replicated delta networks (RDNs) and parallel delta networks (PDNs). For GPDNs, the rearrangeability condition is given and a routing algorithm for the establishment of any set of connection requests is presented. The proposed algorithm operates for GPDNs composed of 2/sup q/*2/sup q/ switching elements and it is able to set up any permutation with a time complexity equal to O(N log/sub 2/ N). The applicability of RDNs, PDNs, and other GPDNs for the implementation of rearrangeable topologies is investigated. In particular, it is proved that if large networks (N>256) have to be implemented, GPDNs require a smaller number of switching elements than RDNs or PDNs.>

This paper deals with the definition of a class of NxN interconnection networks called Parallel Delta Network (PDN). For this class of networks the non-blocking conditions are given. In particular, by means of the graph colouring technique, it has been proved that the minimum number of Delta subnetworks (L) necessary to provide the non-blocking property is L=nfS/21-1 where n is the size of the basic switching element and S the number of stages required by an NxN Delta network. A routing algorithm for the establishment of any permutation has been defined. \nIt operates for any value of n and shows a polynomial time \ncomplexity equal to O(N3/2). Moreover, in case of the setup \nof a single connection request, this algorithm assures a \ntime complexity equal to O(VN). This property makes it \nwell suitable to an asynchronous telecommunication \nenvironment.