Browsing by Author "Chen, Chang-Sheng"

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Building a Temporary VM-based Testing Subsystem for Evaluating the Validity of a Hybrid SSL-VPN System
(2013)
Chen, Chang-Sheng
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Lin, Ming-Hua
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資訊技術服務中心
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Information Technology Services Center
In this paper, we proposed to build a temporary testing system with virtual machine (VM) technology for studying the performance issues (e.g., number of sessions, load-sharing mechanism) and the availability of a newly built hybrid SSL-VPN system before rolling out the service. Moreover, we had designed testing cases to help locate the configuration bugs and/or improper settings, and use them as guidelines for re-adjusting the system configuration to meet the design considerations. As shown in the paper, using the VM technology helps make both the deployment and the test of the SSL-VPN service to become more effective (e.g., easier to reconfigure the system, more scalable).
Developing a VM-based Hybrid DNS System with High Availability
(2013)
Chen, Chang-Sheng
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Su, Chun-Hsien
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資訊技術服務中心
;
Information Technology Services Center
In this paper, we proposed to develop a set of lowcost, virtual machine-based hybrid DNS scheme (i.e., a frontend + multiple backend systems) with a scalable capability to provide DNS services with high availability. In this study, we had built two use case diagrams, namely the frontend (i.e., load-balancer) and the backend (i.e., DNS resolving) subsystems, for modeling the overall system. Moreover, we had developed a two-phase DNS health checking algorithm and designed two testing cases to help implement and evaluate the system. For validating the hybrid scheme, we had deployed and run the proposed DNS system for more than 2 years on our campus network. Based on the collected statistics, we had ensured that the proposed DNS systems could offer the expected DNS services with load-sharing capability and high availability for serving daily DNS queries on a regular basis and run smoothly.
Exploring the correlation between P2P Applications and Network Architecture
(2009)
Chen, Chang-Sheng
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Liu, Ta-Chung
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Su, Chun-Hsien
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交大名義發表
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National Chiao Tung University
Nowadays, P2P applications dominate most of the network traffic and the access pattern poses a serious problem. While some P2P connections are formed within an ISP (or organization), most P2P connections are connected to the rest of the internet, at a high cost to the site. In this paper, we would like to study the topic on how different network architectures (i.e., asymmetric vs. symmetric network) influence the network traffic and the user behaviors with the peer-to-peer (P2P) applications. Many mechanisms could be adopted for improving the network performance of the site.
Learning Sequences Construction Using Ontology and Rules
(2005)
Chen, Ruei-Yan
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Tseng, Shian-Shyong
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Liu, Chien-Liang
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Chang, Chun-Yen
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Chen, Chang-Sheng
n this paper, we propose a SCORM-based (i.e., Shareable Content Object Reference Model), learning sequence construction model using DNS ontology and rules to simplify the complexity of learning sequence construction on DNS Tutoring subsystem of iDNS-KDE (http://idns-kde.nctu.edu.tw) system and to help alleviate the system management issues on the DNS domain.
On Campus Beta Site: Architecture Designs, Operational Experience, and Top Product Defects
(2010-12-01)
Lin, Ying-Dar
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Chen, I-Wei
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Lin, Po-Ching
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Chen, Chang-Sheng
;
Hsu, Chun-Hung
Testing network products in a beta site to reduce the possibility of customer found defects is a critical phase before marketing. We design and deploy an innovative beta site on the campus of National Chiao Tung University, Hsinchu, Taiwan. It can be used for developers to test and debug products, while maintaining network quality for network users. To satisfy the needs of developers, we set up environments and mechanisms, such as a variety of test zones for multiple types of products or systems under test (SUTs), remote control, degrees of traffic volume, and traffic profiling. For network users, we set up mechanisms of failure detection, notification, and recovery. The beta site network users are all volunteers. Test results show that beta site testing is good for finding stability and compatibility defects. The period starting from the beginning of a test until the next defect is found is called the time to fail (TTF). We call it converged if the TTF exceeds four weeks, and the convergence ratio is the percentage of SUTs that reach convergence. We find that the TTF increases with longer test duration, meaning that product quality improves through beta site testing. However, the convergence ratios are only 7 and 20 percent for test durations of one month and one year, respectively, meaning that few products operate faultlessly for a long duration. The convergence ratios also indicate that it takes much more time to enhance product quality to be converged. Therefore, if considering both marketing timing and product quality, one month is our suggested minimum TD for low-end and short-life-cycle products. However, we recommend one year as the minimum TD for high-end and long-life-cycle products.