The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have traffic characteristics and performance requirements that differ dramatically from those of current data-oriented applications, new communication network architectures and protocols will be required. In this paper we discuss the performance requirements and traffic characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research efforts can be considered.

The main contributions of this paper are two-fold. First, we prove fundamental, similarly behaving lower and upper bounds, and give an approximation based on the bounds, which is effective for analyzing ATM multiplexers, even when the traffic has many, possibly heterogeneous, sources and their models are of high dimension. Second, we apply our analytic approximation to statistical models of video teleconference traffic, obtain the multiplexing system's capacity as determined by the number of admissible sources for given cell loss probability, buffer size and trunk bandwidth, and, finally, compare with results from simulations, which are driven by actual data from coders. The results are surprisingly close. Our bounds are based on Large Deviations theory. The main assumption is that the sources are Markovian and time-reversible. Our approximation to the steady state buffer distribution is called "Chernoff-Dominant Eigenvalue" since one parameter is obtained from Chernoff's theorem and t...

We consider an ATM system with an architecture which is designed to accommodate users with very different quality of service requirements. In the base case with only two services, sources which require low loss belong to a High Priority class, and share a FCFS buffer, which has priority access to the trunk. A Low Priority class of sources with typically less stringent requirements on loss have a separate FCFS buffer, which receives the time-varying, residual bandwidth, if any, of the trunk. By administering admission control and restricting the combination of sources to an admissible set, the service guarantees for both classes may be satisfied. The sources are bursty and stochastic fluid models are used to handle burst-scale congestion effects. Our contributions are: (i) we develop simple, fast and robust analytic approximations for the queue distributions in the two buffers; (ii) for admission control, we calculate the admissible set by using our analytic approximations and find that...

We provide models which are capable of describing the long term correlations and self similar burstiness structure found in recent measurements of packet networks and VBR video. Two families of "fractal" arrival processes are presented which capture these features extremely compactly. We show the equivalence of one of these to processes with unsummable auto-correlation functions used recently [16] to describe long term correlation and burstiness. Our approach however has advantages. The other (1 parameter) family generates burstiness on all time scales. It shows how blocking can occur even for arrival streams with zero arrival rate. This illustrates how parameters describing scaling of burstiness and correlation must replace useless long terms averages.

Consider a single-server finite-buffer system. Its stationary random input process is characterized by power spectrum P (!) and input rate steady state distribution f(x). The two functions represent second-order and steady-state input statistics. Here we use the superposition of heterogeneous 2-state Markov chains for construction of P (!) and f(x). The resulting P (!) is a monotone function of j!j, and f(x) is the convolution of heterogeneous binomial functions. The first part of this paper shows how to eliminate the state space explosion in input modeling. Unlike the existing modeling technique which matches 2-state MCs with each individual source, our 2-state MCs are built to statistically match with functions P (!) and f(x) of the aggregate input. The input state space is then reduced by many orders of magnitude. In the second part of this paper, we examine the maximum throughput of a finite-buffer system to support P (!) and f(x) subject to a desired average loss rate L. Our numer...

In this paper we study the effectiveness of Statistical Multiplexing and Buffer Sharing under the multimedia high-speed networking environment. Our focus is on the impact of frequency domain source characteristics on dynamic resource-sharing. By applying a novel statistical matching technique, we have investigated the multiplexing performance of a wide-range of traffic sources. Various operating conditions and different Quality of Service (QoS) requirements have been considered. The objective is to quantify the potential gain in performance due to statistical multiplexing and buffer-sharing under the BISDN, multimedia environment. The trade-offs among different network design alternatives are also discussed. The research reported here was supported by NSF Research Grant NCR-9015757, the Texas Advanced Research Program (TARP-33) and by Southwestern Bell. 1 Introduction An essential feature of the ATM-based solution for BISDN is its potential to use the same set of network resources...

In this paper, we propose and analyze a network architecture for providing QoS statistical guarantees over an internet domain. The architecture is based on the Differentiated Services model, and makes use of the so-called QoS routing and MPLS forwarding to enhance the support of IP Telephony. Our proposed routing scheme is based on QoS intradomain OSPF routing, an extension of the conventional OSPF routing protocol. Processing O/H is shifted from core to edge routers, which compute routes, monitor QoS path quality and enforce Call Acceptance Control (CAC) using the link state information advertised by OSPF. Packet forwarding makes use of the MPLS approach in order to make packet delivery fast and packet overhead small. This research was supported by Cisco, NASA, and NSF. 1 We use analytical results to tune parameters related to the proposed architecture so as to obtain the desired performance in terms of packet loss probability. Via extensive simulation results, we show si...