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255
Effective bandwidths with priorities
 IEEE/ACM Transactions on Networking
, 1998
"... Abstract — The notion of effective bandwidths has provided a useful practical framework for connection admission control and capacity planning in highspeed communication networks. The associated admissible set with a single linear boundary makes it possible to apply stochasticlossnetwork (general ..."
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Cited by 38 (1 self)
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Abstract — The notion of effective bandwidths has provided a useful practical framework for connection admission control and capacity planning in highspeed communication networks. The associated admissible set with a single linear boundary makes it possible to apply stochasticlossnetwork (generalizedErlang) models for capacity planning. In this paper we consider the case of network nodes that use a priorityservice discipline to support multiple classes of service, and we wish to determine an appropriate notion of effective bandwidths. Just as was done previously for the firstin firstout discipline, we use largebuffer asymptotics (large deviations principles) for workload tail probabilities as a theoretical basis. We let each priority class have its own buffer and its own constraint on the probability of buffer overflow. Unfortunately, however, this leads to a constraint for each priority class. Moreover, the largebuffer asymptotic theory with priority classes does not produce an admissible set with linear boundaries, but we show that it nearly does and that a natural bound on the admissible set does have this property. We propose it as an approximation for priority classes. Then there is one linear constraint for each priority class. This linearadmissibleset structure implies a new notion of effective bandwidths, where a given connection is associated with multiple effective bandwidths: one for the priority level of the given connection and one for each lower priority level. This structure can be used regardless of whether the individual effective bandwidths are determined by largebuffer asymptotics or by some other method. 1
Analysis of OnOff Patterns in VoIP and Their Effect on Voice Traffic Aggregation
 In Proc. of ICCCN 2000
, 2000
"... We present an experimental analysis of onoff patterns in Voice over IP (VoIP), where we study the talkspurt/gap distribution produced by two modern silence detectors: ITU G.729 Annex B Voice Activity Detector (VAD) and NeVoT Silence Detector (SD). The results indicate that spurt/gap distributions ..."
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Cited by 37 (2 self)
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We present an experimental analysis of onoff patterns in Voice over IP (VoIP), where we study the talkspurt/gap distribution produced by two modern silence detectors: ITU G.729 Annex B Voice Activity Detector (VAD) and NeVoT Silence Detector (SD). The results indicate that spurt/gap distributions are fairly sensitive to both the sound volume and the type of silence detectors, but all of them showed that the traditional assumption of exponential distribution does not always fit well with the audio sessions we recorded. Both the spurt and gap distributions are more "heavytailed" than the exponential curve. In particular, the gap distribution deviates much more strongly from the exponential model, even when "hangover" is applied.
QoS provided by the IEEE 802.11 Wireless LAN to Advanced Data Applications: a Simulation Analysis,” ACM/Baltzer Wireless Networks Journal
, 2000
"... IEEE 802.11 is a Media Access Control (MAC) protocol which has been standardized by IEEE for Wireless Local Area Networks (WLANs). The IEEE 802.11 MAC protocol offers two types of services to its users: synchronous and asynchronous. This paper presents an indepth analysis, by simulation, of the asy ..."
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Cited by 35 (1 self)
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IEEE 802.11 is a Media Access Control (MAC) protocol which has been standardized by IEEE for Wireless Local Area Networks (WLANs). The IEEE 802.11 MAC protocol offers two types of services to its users: synchronous and asynchronous. This paper presents an indepth analysis, by simulation, of the asynchronous part alone. The analysis is performed by considering station data traffic patterns (hereafter advanced data traffic) which have a very similar shape to traffic generated by WWW applications. We carried out the simulation by taking into consideration two classes of scenarios: balanced and unbalanced. In the former class each station has the same offered load while in the latter class a specific station is more loaded than the others. Our conclusion is that the IEEE 802.11 MAC protocol performs satisfactorily for both classes of scenarios, although performance measures with advanced traffic are worse than the corresponding performance measures with Poissonian traffic. Furthermore, we broadened our analysis to include higher medium capacities than those planned (i.e., 1 and 2 Mbit=sec) up to 10 Mbit=sec. This part of the analysis shows that the IEEE 802.11 MAC protocol is not adequate to work at speeds planned for the forthcoming ATM Wireless LAN. 1.
Stochastic Modeling Of Traffic Processes
 Frontiers in Queueing: Models, Methods and Problems
, 1996
"... Modern telecommunications networks are being designed to accomodate a heterogenous mix of traffic classes ranging from traditional telephone calls to video and data services. Thus, traffic models are of crucial importance to the engineering and performance analysis of telecommunications system, nota ..."
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Cited by 30 (0 self)
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Modern telecommunications networks are being designed to accomodate a heterogenous mix of traffic classes ranging from traditional telephone calls to video and data services. Thus, traffic models are of crucial importance to the engineering and performance analysis of telecommunications system, notably congestion and overload controls and capacity estimation. This chapter surveys teletraffic models, addressing both theoretical and computational aspects. It first surveys the main classes of teletraffic models commonly used in teletraffic modeling, and then proceeds to survey traffic methods for computing statistics relevant to the engineering a teletraffic network. 1 INTRODUCTION Traffic is the driving force of telecommunications systems, representing customers making phone calls, transferring data files and other electronic information, or more recently, transmitting compressed video frames to a display device. The most common modeling context is queueing; traffic is offered to a qu...
A Quantitative Comparison of Scheduling Algorithms for InputQueued Switches
 Computer Networks and ISDN Systems
, 1997
"... This paper quantitatively evaluates several alternative approaches to the scheduling of cells in a highbandwidth inputqueued ATM switch. In particular, we compare the performance of three algorithms described previously: FIFO queueing, parallel iterative matching (PIM), maximum matching and two new ..."
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This paper quantitatively evaluates several alternative approaches to the scheduling of cells in a highbandwidth inputqueued ATM switch. In particular, we compare the performance of three algorithms described previously: FIFO queueing, parallel iterative matching (PIM), maximum matching and two new algorithms: iterative roundrobin matching with slip (SLIP) and leastrecently used (LRU). For the synthetic workloads we consider, including uniform and bursty traffic, SLIP performs almost identically to the other algorithms. Cases for which PIM and SLIP perform poorly are presented, indicating that care should be taken when using these algorithms. But, we show that the implementation complexity of SLIP is an order of magnitude less than for PIM, making it feasible to implement a 32x32 switch scheduler for SLIP on a single chip. 1 Introduction The past few years has seen increasing interest in arbitrary topology cellbased local area networks, such as ATM [5]. In these networks, hosts a...
Decomposition of General Queueing Networks with MMPP Inputs and Customer Losses
 In Proc. 4th Int. Workshop on Queueing Networks with Finite Capacity
, 2000
"... For nontrivial general (open) queueing networks, decomposition often represents the only feasible solution method besides simulation. The network is partitioned into individual nodes which are analyzed in isolation with respect to approximate internal trac representations. The quality of the quickly ..."
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Cited by 30 (6 self)
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For nontrivial general (open) queueing networks, decomposition often represents the only feasible solution method besides simulation. The network is partitioned into individual nodes which are analyzed in isolation with respect to approximate internal trac representations. The quality of the quickly obtained results very much depends on the descriptors for the trac processes within the network, which may be split and merged before traversing the next queue. Recently, one of the existing decomposition formalisms based on renewal processes as trac descriptors has been extended in order to include semiMarkov processes (SMPs) and Markovmodulated Poisson processes (MMPPs) with two states. However, due to the restriction to tandem networks, no operations for the splitting and and merging were provided.
Improved Loss Calculations at an ATM Multiplexer
 IEEE/ACM Transactions on Networking
, 1998
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Practical TimeScale Fitting of SelfSimilar Traffic with MarkovModulated Poisson Process
, 2001
"... Recent measurements of packet/cell... In this paper, we first give some definitions of selfsimilarity. Then, we propose a fitting method for the selfsimilar traffic in terms of Markovmodulated Poisson process (MMPP). We construct an MMPP as the superposition of twostate MMPPs and fit it so as to ..."
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Cited by 26 (2 self)
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Recent measurements of packet/cell... In this paper, we first give some definitions of selfsimilarity. Then, we propose a fitting method for the selfsimilar traffic in terms of Markovmodulated Poisson process (MMPP). We construct an MMPP as the superposition of twostate MMPPs and fit it so as to match the variance function over several timescales. Numerical examples show that the variance function of the selfsimilar process can be well represented by that of resulting MMPPs. We also examine the queueing behavior of the resulting MMPP/D/1 queueing systems. We compare the analytical results of MMPP/D/1 with the simulation ones of the queueing system with selfsimilar input.
RealTime Traffic Measurements on MAGNET II
, 1990
"... Realtime traffic measurements on MAGNET II, an integrated network testbed based on Asynchronous Time Sharing, are reported. The quality of service is evaluated by monitoring the buffer occupancy distribution, the packet time delay distribution, the packet loss and the gap distribution of the consec ..."
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Cited by 25 (14 self)
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Realtime traffic measurements on MAGNET II, an integrated network testbed based on Asynchronous Time Sharing, are reported. The quality of service is evaluated by monitoring the buffer occupancy distribution, the packet time delay distribution, the packet loss and the gap distribution of the consecutively lost packets. Our experiments show that both time delay and buffer occupancy distributions of multiplexed video sources display a marked bimodal behavior, which does not seem to depend on the buffer size. The reliance of the network designer on traffic sources that do not exhibit substantial correlations can lead to implementations with serious congestion problems. For ATS based networks with different traffic classes, the impact of a traffic class on the performance of the other classes tends to be diminished when compared with one class based ATM networks. March 23, 1995. Published in IEEE Journal on Selected Areas in Communications, April 1990 RealTime Traffic Meas...