In the future asynchronous transfer mode (ATM) networks, an efficient virtual path (VP) control strategy must be applied to guarantee the network has high throughput with tolerable node processing load. The multistage VP control may be the best candidate since the tasks in this method are shared by the central node and local nodes, and it allows us to track the traffic changes while maintain a good state of the VP topology by reconfiguring it at regular or need based intervals. In this paper, we focus on the VP topology optimization problem in the multistage VP control. We first present the problem formulation in which the tradeoff between the network throughput and processing costs is considered, and then employ an algorithm based on a route-neuron Hopfield neural network (HNN) model to solve this problem. The numerical results demonstrate the HNN can converge to optimal solutions with high probability and stability while in other cases to near optimal solutions if the values of the system parameters in the route-neuron model are chosen according to some empirical formulas provided in this paper.

In this paper, we propose a new multicast routing algorithm for constructing the delay-constrained minimal spanning tree in the VP-based ATM networks, in which we consider the efficiency even in the case where the destination dynamically joins/departs the multicast connection. For constructing the delay-constrained spanning tree, we first generate a reduced network consisting of only VCX nodes from a given ATM network, originally consisting of VPX/VCX nodes. Then, we obtain the delay-constrained spanning tree with a minimal tree cost on the reduced network by using our proposed heuristic algorithm. Through numerical examples, we show that our dynamic multicast routing algorithm can provide an efficient usage of network resources when the membership nodes frequently changes during the lifetime of a multicast connection, while the existing multicast routing algorithm may be useful for constructing the multicast tree with a static nature of destination nodes. We also demonstrate that more cost-saving can be expected in dense networks when applying our proposed algorithm.

This paper discusses the problems in designing virtual-path (VP) networks and underlying transmission-path (TP) networks using the "self-sizing" capability. Self-sizing implies an autonomous adjustment mechanism for VP bandwidths based on traffic conditions observed in real time. The notion of "bandwidth demand" has been introduced to overcome some of the problems with VP bandwidth sizing, e.g., complex traffic statistics and diverse quality of service requirements. Using the bandwidth demand concept, a VP-bandwidth-sizing procedure is proposed in which real-time estimates of VP bandwidth demand and successive VP bandwidth allocation are jointly utilized. Next, TP bandwidth demand, including extra capacity to cover single-link failures, is defined and used to measure the congestion level of the TP. Finally, a TP provisioning method is proposed that uses TP "lifetime" analysis.

In this paper, we propose a new design method to construct the highly reliable ATM network based on the virtual path (VP) concept. Through our method, we can guarantee a network survivability, by which we mean that connectivity between every pair of two end nodes is assured even after the failure, and that quality of service (QoS) requirements of each VC connection are still satisfied. For achieving a reliable network, every VP connection between two end nodes is equipped with a secondary VP connection such that routes of primary and secondary VPs are established on completely disjoint physical paths. Our primary objective of the current paper is that the construction cost of the VP-based network with such a survivability is minimized while the QoS requirement of traffic sources in fulfilled. For this purpose, after all the routes of VPs are temporarily established by means of the shortest paths, we try to minimize the network cost through (1) the alternation of VP route and (2) the separation of a single VP into several VPs, and optionally through (3) the introduction of VCX nodes. Through numerical examples, we show how the increased cost for the reliable network can be sustained by using our design method.

An ATM network design algorithm is treated as a resource allocation problem. As an effective way to facilitate a coexistence of traffic with its diverse characteristics and different quality of service (QOS) requirements in ATM networks, a virtual path (VP) concept has been proposed. In attempting to design the VP (Virtual Path)-based ATM network, it requires to consider a network topology and traffic pattern generated from users for minimizing a network construction cost while satisfying QOS requirements such as cell / call loss probabilities and cell delay times. In this paper, we propose a new heuristic design algorithm for the VP-based ATM network under QOS constraints. A minimum bandwidth required to transfer a given amount of traffic is first obtained by utilizing an equivalent bandwidth method. After all the routes of VPs are temporarily established by means of the shortest paths, we try to minimize the network cost through the alternation of VP route, the separation of a single VP into several VPs, and the introduction of VCX nodes. To evaluate our design algorithm, we consider two kinds of traffic; voice traffic as low speed service and still picture traffic as high speed service. Through numerical examples, we demonstrate that our design method can achieve an efficient use of network resources, which results in the cost-effective VP-based ATM network.