956
Performance of TCP/IP Using ATM ABR and UBR Services over Satellite Networks
We study the buffering requirements for zero cell loss for TCP/IP over satellite links using the available bit rate (ABR) and unspecified bit rate (UBR) services of asynchronous transfer mode (ATM) networks. For the ABR service, we explore the effect of feedback delay (a factor which depends upon the position of the bottleneck), the switch scheme used, and background variable bit rate (VBR) traffic. It is shown that the buffer requirement for TCP over ABR is independent of the number of TCP sources, but depends on the aforementioned factors. For the UBR service, we show that the buffer requirement is the sum of the TCP receiver window sizes. We substantiate our arguments with simulation results.
609563
A definition of general weighted fairness and its support in explicit rate switch algorithms
We give a general definition of weighted fairness and discuss how a pricing policy can be mapped to general weighted (GW) fairness. The GW fairness can be achieved by calculating the excess fairshare (weighted fairshare of the left over bandwidth) for each VC. We show how a switch algorithm can be modified to support the GW fairness by using the excess fairshare term. We use ERICA+ as an example switch algorithm and show how it can be modified to achieve the general fairness. Simulations results are presented to demonstrate that, the modified switch algorithm achieves GW fairness. An analytical proof for convergence of the modified ERICA+ algorithm is given in the appendix.
5318665
Providing rate guarantees to TCP over the ATM GFR service
The ATM guaranteed frame rate (GFR) service is intended for best effort traffic that can benefit from minimum throughput guarantees. Edge devices connecting LANs to an ATM network can use GFR to transport multiple TCP/IP connections over a single GFR VC. These devices would typically multiplex VCs into a single FIFO queue. It has been shown that in general, FIFO queuing is not sufficient to provide rate guarantees, and per-VC queuing with scheduling is needed. We show that under conditions of low buffer allocation, it is possible to control TCP rates with FIFO queuing and buffer management. We present analysis and simulation results on controlling TCP rates by buffer management. We present a buffer management policy that provides loose rate guarantees to SACK TCP sources when the total buffer allocation is low. We study the performance of this buffer management scheme by simulation.
3204907
Performance of Bursty World Wide Web (WWW) Sources over ABR
Bobby Vandalore, Shivkumar Kalyanaraman, Raj Jain, Rohit Goyal, Sonia Fahmy The Ohio State University, Department of CIS Columbus, OH 43210-1277 Phone: 614-688-4482, Fax: 614-292-2911 Email: fvandalor, shivkuma, jain, goyal, fahmyg@cis.ohio-state.edu Seong-Cheol Kim Principal Engineer, Network Research Group, Communication Systems R&D Center Samsung Electronics Co. Ltd., Chung-Ang Newspaper Bldg. 8-2, Karak-Dong, Songpa-Ku, Seoul, Korea 138-160 Email: kimsc@metro.telecom.samsung.co.kr Abstract
16677800
AQuaFWiN: adaptive QoS framework for multimedia in wireless networks and its comparison with other QoS frameworks
In a wireless environment, due to topology changes and characteristics of media (interference in radio signals) the bandwidth of a link is unpredictable and possibly very low, the error rates are variable and extremely high. Provisioning and guaranteeing quality of service (QoS) in such an environment is a very challenging problem. In this paper we propose an adaptive and QoS framework to support multimedia applications in a wireless networking environment. The proposed framework is hierarchical in nature with cluster of mobile end hosts connected to a base station, base stations are connected to a supervisory node, which in turn is connected to the wired infrastructure. The changing conditions in wireless due to interference and possibly mobility, entitle that the real-time applications needing stringent QoS should be adaptable. The framework uses a generic feedback mechanism to support adaptability at all layers of the wireless network. An overview of existing wireless architectures which support QoS is given. The architectures discussed are WAMIS (wireless adaptive multimedia information system), SWAN (seamless wireless ATM network), MMWN (multimedia support for mobile wireless networks), and QGMC (QoS guarantees in mobile computing). The proposed approach is compared with these existing methods.
789958
Myths about Congestion Management in High Speed Networks
Weaknesses in several recently proposed ideas about congestion control and avoidance in high-speed netwroks are identified. Both sides of the debate concerning prior reservation of resources versus walk-in service, open-loop control versus feedback control, rate control versus window control, and router-based control versus source-based control are presented. The circumstances under which backpressure is useful or not are discussed, and it is argued that a single congestion scheme is not sufficient, but that a combination of several schemes is required for complete congestion management in a network.
5420102
Dynamic RDT Model for Data Mining
16168118
Defect-aware design paradigm for reconfigurable architectures
With advances in process technology, the feature sizes are decreasing, which leads to higher defect densities. More sophisticated techniques, at increased costs are required to avoid defects. If nanotechnology based fabrications are applied, the yield may even go down to zero, as avoiding defects during fabrication will not be a feasible option. Hence, future architectures have to be defect-tolerant. Most of the current defect-tolerance schemes introduce redundancy in architecture to combat defects. Alternatively we can introduce defect tolerance in the design-flow. In this paper we analyze the bottlenecks faced by current design-methodologies while addressing defect tolerance. We study the performance of present place and route tools on a defective fabric in terms of area and critical delay penalty, and explore routing aware placement in this context. We have proposed a new cost function, CA-RISA for improving the performance in a defect-aware environment
13296348
Variability in the execution of multimedia applications and implications for architecture
Multimedia applications are an increasingly important workload for general-purpose processors. This paper analyzes frame-level execution time variability for several multimedia applications on general-purpose architectures. There are two reasons for such an analysis. First, it has been conjectured that complex features of such architectures (e.g., out-of-order issue) result in unpredictable execution times, making them unsuitable for meeting real-time requirements of multimedia applications. Our analysis tests this conjecture. Second, such an analysis can be used to effectively employ recently proposed adaptive architectures.
We find that while execution time varies from frame to frame for many multimedia applications, the variability is mostly caused by the application algorithm and the media input. Aggressive architectural features induce little additional variability (and unpredictability) in execution time, in contrast to conventional wisdom.
The presence of frame-level execution time variability motivates frame-level architectural adaptation (e.g., to save energy). Additionally, our results show that execution time generally varies slowly, implying it is possible to dynamically predict the behavior of future frames on a variety of hardware configurations for effective adaptation.
39032710
Refining decision tree classifiers using rough set tools
The proposed hybridized rough set framework is composed of traditional Rough Set (RS) approach and classical Decision Tree (DT) induction algorithm. RS helps to identify dominant attributes and DT algorithm results in simpler and generalized classifier. The implementation of the Hybridized Rough Set Framework is presented as the RDT algorithm. GA heuristics are used to generalize the RDT algorithm further. Experimental results obtained on applying the hybridized rough set framework and the related base algorithms on datasets belonging to the three categories are presented in this paper. Accuracy, complexity, number of rules and number of attributes in the induced classifier assess the performance of the candidate algorithms. The results indicate that the proposed framework is an effective model for classification.
2278641
Classifying Mushrooms in the Hybridized Rough Sets Framework