Browsing by Author "Ngai, Patrick"

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Network Performance Bottleneck Detection and Maximum Network Throughput Estimation for Datacenter Applications
(2016)
Ngai, Patrick
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Lu, Sung-Jer
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Wu, Yu-Sung
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Lim, Wei-Sheng
;
Lin, Tung-Yueh
For applications deployed in third-party datacenter environments to attain cost-effective performance, it requires precise provisioning of hardware resources such as assigning appropriate network bandwidth to an application. However, it is not always clear how much resource should be assigned to an application. In this work, we propose NBD (Network performance Bottleneck Detector) to detect the network bandwidth requirement of a datacenter application. NBD is fully transparent and does not require modification of applications. It correctly reports the required bandwidth of an application even when the preset network bandwidth is far below the required bandwidth. NBD employs a novel technique called network flow distortion for the estimation of application network bandwidth requirement. The evaluation results indicate that NBD is effective and only incurs mild performance overhead.
Towards Consistent Software Defined Networking with Logic Programming
(2015)
Lui, Eric
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Wu, Yu-Sung
;
Ngai, Patrick
;
Lin, Tung-Yueh
;
Li, Hong-Wei
Software Defined Networking (SDN) allows the construction of virtual networks on top of a datacenter network infrastructure. However, the flexibility also increases the chance of inconsistencies in the network configurations caused by component failures, software bugs, or human errors. The inconsistencies may result in service outage or security policy violation. We propose a model-based verification system to check the consistency of a virtual network. The system models the requirements as logic constraints and extracts the configuration states of a virtual network. The configuration states are checked against the logic constraints by using a SMT solver[1]. The prototype system successfully detects various inconsistencies injected to the testbed and incurs reasonable amount of overheads.