| 1. |
- Jena, Ajit K., et al.
(författare)
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Modeling and Evaluation of Network Applications and Services
- 1999
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Konferensbidrag (refereegranskat)abstract
- The global Internet has seen tremendous growth in terms of nodes and user base as well as of types of applications. One of the most important consequences of this growth is related to an increased complexity of the traffic experienced in these networks. Each application has a set of unique characteristics in terms of its performance characteristics, its transactions as well as the way the transaction processing profile maps onto unique network resource requirements. In order to support Internet applications effectively, it is therefore important to understand and to characterise the application level transactions. Recent advances in high resolution traffic monitoring and analysis capabilities have enabled us to build up realistic models for diverse network applications. In this paper we report investigations of classical applications such as FTP, SMTP, and HTTP to evaluate end-to-end network performance requirements. Our results show the presence of a robust correlation structure in the traffic streams that has a fundamental bearing on the user perceived quality of the applications.
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| 2. |
- Jena, Ajit K., et al.
(författare)
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Resource Engineering for Internet Applications
- 1999
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Konferensbidrag (refereegranskat)abstract
- Recent measurements on LAN, MAN and WAN traffic have demonstrated that Long-Range Dependence (LRD) is an invariant property irrespective of network technology being employed. As a consequence, the performance of the network is dominated by the property of LRD in the network traffic. Latency in information access is one of the most important factors in the user perceived Quality of Service (QoS) in network applications. Almost all the applications follow the client-server paradigm to transfer information entities which are typically files or typed-in messages. The distribution of the sizes of these information entities are best described by heavy-tailed distributions and results in LRD. This fundamental property impacts all the aspects of application layer performance (e.g., response time) and the network layer performance (e.g., packet loss and delay). In the traditional traffic models, the network resource management is aimed at capturing the timescales at which bursts occur and dimensioning the network for the burst sizes occuring at that timescale. This management paradigm has proven to be ineffective for the traffic having significant level of LRD. Because of LRD, bursts of all possible sizes occur at timescales spanning over several orders of magnitude. Engineering of network resources to protect application layer QoS is therefore an important task. In this paper heavy-tailed distributions are used to model the information contents transferred by some of the classical network applications such as FTP, SMTP and HTTP. The parameters of these models are based on high resolution non-intrusive monitoring of busy periods in live networks. The clients and the servers are modelled as ON-OFF sources producing LRD phenomena at the packet level through aggregation. The user level quality for these applications is investigated (in terms of end-to-end delay performance) and preliminary results are reported showing how the quality is affected by the bandwidth and buffer allocation schemes.
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| 3. |
- Jena, Ajit K., et al.
(författare)
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Traffic Control in ATM Networks : Engineering Impacts of Realistic Traffic Processes
- 1996
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Konferensbidrag (refereegranskat)abstract
- This paper reviews the current state of the art in the rapidly developing areas of ATM traffic controls and traffic modeling, and identifies future research areas to facilitate the implementation of control methods that can support a desired quality of service without sacrificing network utilizations. Two sets of issues are identified, one on the impacts of realistic traffic on the efficacy of traffic controls in supporting specific traffic management objectives, and the other dealing with the extend to which controls modify traffic characteristics. These issues are illustrated using the example of traffic shaping of individual ON-OFF sources that have infinite variance sojourn times.
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| 4. |
- Pruthi, Parag, et al.
(författare)
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HTTP Interactions with TCP
- 1998
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe our simulation models for evaluating end-to-end performance of HTTP transactions. We first analyze several gigabytes of collected traffic traces from a production Frame Relay network. Using these traces we extract web traffic and analyze the server web pages accessed by actual users. We analyze over 25000 web pages and develop a web client/server interaction model based upon our analysis of many server contents. We make specific contributions by analyzing the popularity of web servers and the number of bytes transferred from them during a busy hour. We also compute the distribution of the number of embedded items within a web document. We then use these models to drive a network simulation and show the interactions between the TCP/IP flow control and retransmission mechanism on source parameters. One of our important contributions has been to show that the Hurst parameter is robust with regard to TCP/IP flow and error control. Using the simulation studies we show that the distribution of end-to-end application message delay has a heavy-tail distribution and we discuss how these distributions arise in the network context.
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