Browsing by Author "Lai, Yu-Kuen"

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A scalable and accurate distributed traffic generator with Fourier transformed distribution over multiple commodity platforms
(2019-10-15)
Chang, Ching-Hao
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Lin, Ying-Dar
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Lai, Yu-Kuen
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Lai, Yuan-Cheng
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資訊工程學系
The rapid growth of high-speed computer networks poses a challenge in the design of testing and verification equipment. The hardware-based packet generators that are often used in the verification process are accurate but costly. Software-based packet generators, on the other hand, are relatively low-cost but have a limited performance with low accuracy. This paper proposes a Fourier-based profile decomposition and formulation methodology for a distributed packet generating system, featuring good horizontal scalability and high accuracy. Different from traditional software-based packet generators, this proposed system extracts the traffic components from a specific traffic distribution applying Fourier transformation to generate traffic components. These traffic components are distributed to one or more worker nodes for packet generation, and thus achieving higher aggregated traffic rate in any given distribution. The system design is based on the Data Plane Development Kits (DPDK) framework to maximize the traffic generation performance. The accuracy and performance of the proposed system scale according to the number of worker nodes used. Currently, with multiple CPU cores and five workers, the proposed system can generate aggregated traffic of more than 40 Gbps in a Poisson distribution.
Generic Validation Criteria and Methodologies for SDN Applications
(2019-12-01)
Lin, Ying-Dar
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Lai, Yu-Kuen
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Tsou, Yung-Liang
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Lai, Yuan-Cheng
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Liou, En-Cheng
Programmable control plane in software-defined networking (SDN), plays an essential role in the SDN architecture. The network function provided by the specialized hardware in a legacy network can be created in the form of software-based "SDN application" running on the controllers to manipulate entire network configurations. Therefore, the risk of having software bugs and errors in the SDN applications may threaten the normal operations of SDN networks. This paper presents systematic validation criteria and test cases based on the proposed novel methodologies for SDN application testing. The test framework can perform testbed build-up, generate desired packet sequences, and analyze results automatically. According to the results of a generic test suite, several issues are unveiled in the application under test (AUT). Some AUTs, which need to check all the incoming packets from Open-Flow switches, fail to meet the test criteria of burst packet-in and flow self-recycling. For most of the applications based on the Ryu controller, the evaluation results reveal that some are unable to recycle flow entries after they are unloaded. It is recommended that all flows populated by SDN applications must have timeout value specified to prevent unnecessary entries kept in the flow table.
OFBench: Performance Test Suite on OpenFlow Switches
(2018-09-01)
Lin, Ying-Dar
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Lai, Yu-Kuen
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Wang, Chen-You
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Lai, Yuan-Cheng
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資訊工程學系
Performance issues of Open Flow switches are attracting a lot of attention owing to the potential large-scale deployment of software-defined devices. This paper presents the OFBench which is an automatic test suite for evaluating the performance of OpenFlow switches. The design, as part of the Automation Control Test System (ACTS) development, is based on a controller-agent architecture which allows the development of test cases that are written in a high-level script language. In addition to the end-toend measurement methodology, novel methods are proposed to further profile the internal performance metrics, which are difficult to get due to the black-box nature of the device under test. The prototype of this suite currently comprises five test cases to evaluate five performance metrics, which are action time, pipeline time, buffer size, pipeline efficiency, and timeout accuracy. OpenFlow switches are evaluated and three issues are observed associated with switches during the testing. First, some switches may not be well implemented in the design of apply-action instructions. Second, some switches suffer from random crashes with a high volume of bursty packet-in traffic. Finally, the timer of idle-timeout is often not reset properly with matching flow entry.