Journal of High Speed Networks - Volume 6, issue 4

Authors: Ajmone Marsan, M. | Bianco, A. | Gibert Abos, E. | Leonardi, E.

Article Type: Research Article

Abstract: The paper discusses the performance of access strategies for all‐optical packet networks based on a WDM multichannel ring topology with a number of synchronized slotted channels; nodes are equipped with one tunable receiver, one tunable transmitter, a variable number of delay lines and optical switches, and a FIFO transmission queue. Several access strategies based on local status information are described and compared, taking as performance indices packet loss probability, and maximum achievable throughput. We show that, among the considered proposals, the most efficient is a simple strategy that guarantees loss‐free transmission.

Citation: Journal of High Speed Networks, vol. 6, no. 4, pp. 237-246, 1997

Authors: Ahn, David S. | Lee, Myung J.

Article Type: Research Article

Abstract: One of the important issues in an ATM switch design is how to allocate the given buffer budget to ensure compliance with negotiated traffic contracts of each ATM connection. This problem owes mainly to the conflicting buffer requirements of different QoS parameters, such as cell loss, cell transfer delay, and cell delay variation. For example, increasing the buffer size of a connection at a switch may reduce cell loss due to buffer overflow, but the benefit of adding buffers possibly causes an excessive queueing delay due to increased buffer sizes. In this paper, such trade‐off issue in buffer allocation for …different QoS requirements at a switch are quantified by a single nodal QoS parameter called Effective Cell Loss (ECL), in which both cell loss due to buffer overflow and cell loss due to excessive delay are properly integrated. The immediate benefit, among many others, of imposing ECL at switches is an optimal buffer allocation resulted by the conflicting buffer requirements of cell loss and cell delay parameter. Consequently, given the acceptable cell loss probability, the maximum cell delay tolerance, and the fixed buffer budget at an ATM switch, an optimal buffer allocation is found by minimizing ECL. Therefore, ECL is an effective QoS parameter that provides not only the most faithful way to comply with negotiated traffic contracts but also an optimal buffer allocation for a given buffer budget at a switch. Furthermore, we present the effectiveness of using ECL at a switch under nonuniform traffic arrival. Show more

Citation: Journal of High Speed Networks, vol. 6, no. 4, pp. 247-262, 1997

Authors: Thomas, Panagiotis | Teneketzis, Demosthenis

Article Type: Research Article

Abstract: We present an approach to Service Provisioning with Quality of Service (QoS) requirements in ATM networks. The ATM network provides services to users every \widehat{T} units of time. Each service is characterized by its one way route, its input traffic constraints and its provided QoS. The input traffic constraints consist of the maximum input rate and an upper bound on the burstiness curve. The QoS provided is defined by the maximum percentage of cell loss along the route and the maximum end‐to‐end cell delay. The service provisioning problem is defined as follows: determine the amount, price and required …resources (bandwidth and buffers) for each type of service, that maximize a social welfare function that consists of the network’s revenue and the users’ surplus. This problem is solved every \widehat{T} units of time and the allocation is made only over the available resources, that is, those that are not used by connections that are still active. We prove the existence of a solution to the Service Provisioning Problem and we also suggest an iterative procedure that interprets the solution. The network adjusts the prices to maximize the welfare function and also to guarantee that the allocated resources do not exceed the available resources. Based on these prices, users request a new allocation that minimizes their cost and the network adjusts again the prices based on the new allocation. The above procedure has the following features: (i) the network needs to know only the average request rate for each type of service, their route and the resources requested by the users; (ii) users need to know only their private information (input traffic constraints and QoS requirements), their route, and the prices for resources announced by the network. Show more

Citation: Journal of High Speed Networks, vol. 6, no. 4, pp. 263-291, 1997

Authors: Meng, W. | Habib, I. | Saadawi, T.N.

Article Type: Research Article

Abstract: A media access control (MAC) protocol supporting Slot Reuse for improving the performance of S++ networks, called group addressing simple double plus and denoted by S++‐GA, is presented. S++‐GA obtains higher performance than S++ via a four‐fold approach: (1) Dividing all the nodes in S++‐GA into multiple groups and assigning each group a group code. (2) Establishing a post‐destination group slot release rule that releases a busy slot after the busy slot departs from its destination group. (3) Introducing a modified transmission rule, named group transmission rule. (4) Modifying cyclic bandwidth‐allocation rule of S++. In contrast to S++ with Destination …Release (DR) (S++‐DR) or with Erasure Nodes (EN) (S++‐EN), S++‐GA buffers only partial node‐address for slot release but not the whole node‐address or the whole slot. So, the system latency and access delay of S++‐GA are less than those of S++‐DR and S++‐EN. Show more

Citation: Journal of High Speed Networks, vol. 6, no. 4, pp. 293-307, 1997