This paper investigates performance and engineering issues concerning a multiplexer scheme that has been implemented in AT&T's Integrated Access Terminal (IAT) to transport packetized voice and data traffic on shared facilities. The multiplexer serves voice and data traffic according to a dynamic bandwidth allocation scheme in order to simultaneously meet their performance requirements. A bit-dropping procedure is employed for voice packets to provide a graceful degradation of voice quality under overload conditions. An analytical model is developed for the multiplexer service scheme that estimates performance parameters given the voice and data offered loads. The model is used to demonstrate the capacity advantages of dynamic bandwidth allocation, and to generate load-service curves that illustrate the tradeoffs of carrying different combinations of voice and data traffic on the multiplexer. Sensitivity of voice and data performance to the multiplexer time-slice parameters is also investigated. The model is readily embedded in a design approach that determines the bandwidth required to carry the voice and data traffic demands while satisfying all desired performance objectives.>

The performance of local area networks (LANs) bridged through a virtual-circuit-based wide area network (WAN) is analyzed. The focus is on understanding end-to-end performance issues from an applications point of view. Results that can be used to traffic engineer the network to meet end-user service objectives on interactive response time and bulk data transfer throughput are derived. It is demonstrated that the use of a windowing protocol in the wide area network provides a robust control mechanism for regulating traffic and delivering high performance.>

The authors continue an investigation of the way diverse traffic from different data applications affects the performance of packet queues. This traffic often exhibits significant dependence among successive interarrival times, among successive service times, and between interarrival times and service times, which can cause a significant degradation of performance under heavy loads (and often even under moderate loads). This dependence and its effects on performance (specifically, the mean steady-state workload) are partially characterized here by the cumulative correlations in the total input process of work, which is referred to as the index of dispersion for work (IDW). The authors evaluate approximations for the mean steady-state workload based on the IDW by making comparisons with computer simulations.>

Error performance issues concerning IEEE Standard 802.6 metropolitan area networks (MANs) which will be based on fiber transmission systems are investigated. The error protection requirements for MAN cell headers are studied, and a simple cyclic redundancy check (CRC)-based scheme to provide single-bit correction and multiple-bit detection is proposed. The functions of the adaptation layer for data end points are discussed. A critical function of the data adaptation layer is to prevent corruption of information carried in 802.6 cells. Alternative ways of providing error protection are discussed and analyzed. It is shown that the alternative based on a CRC check per segment provides robust error protection and is amenable to very-high-speed implementation.>

The burstiness of the total arrival process has been previously characterized in packet network performance models by the dependence among successive interarrival times. It is shown that associated dependence among successive service times and between service times and interarrival times also can be important for packet queues involving variable packet lengths. These dependence effects are demonstrated analytically by considering a multiclass single-server queue with batch-Poisson arrival processes. For this model and more realistic models of packet queues, insight is gained from heavy-traffic limit theorems. This study indicates that all three kinds of dependence should be considered in the analysis and measurement of packet queues involving variables packet lengths. Specific measurements are proposed for real systems and simulations. This study also indicates how to predict expected packet delays under heavy loads. Finally, this study is important for understanding the limitations of procedures such as the queuing network analyzer (QNA) for approximately describing the performance of queuing networks using the techniques of aggregation and decomposition.>

This paper is concerned with modeling and control strategy interaction in a multimodel context. The role of the observability structure in multiple deeisionmaker (DM) problems is examined. A procedure is developed for generating multimodel solutions based on certain deterministic information patterns. This is achieved by first explicitly identifying the state space structure induced by the observation sets of the DM's, and then overlapping appropriately the input space structure of each DM. Such a representation is used to identify the class of admissible strategies which generate multimodel solutions. Conditions, which depend on the information pattern, are obtained under which these multimodel solutions admit partial noninteraction among the DM's.