Browsing by Author "Ho, Cheng-Yun"

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A Case Study of Cache Performance in ICN - Various Combinations of Transmission Behavior and Cache Replacement Mechanism
(2015)
Ho, Cheng-Yun
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Ho, Cheng-Yuan
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
Information-centric networking (ICN) is suggested by many papers and research projects to improve network performance and enhance network resource efficiency in recent years. Moreover, in these researches, some researchers not only proposed their ideal ICN approaches but also modified the existing cache replacement mechanism to fit their ICN approaches. In this paper, we aim at investigating and quantifying the effect of the cache hit ratio with two kinds of transmission behavior, sequential and un-sequential, and three cache replacement mechanisms, FIFO, LRU, and random, in ICN. We implement several simulations with ndnSIM under NS-3 simulator. The simulation results show that LRU and FIFO are suitable for all networking applications no matter sequential or un-sequential content transmission behavior is used. Besides, the simulation results reveal that the cache hit ratios in LRU and FIFO are same when the experiment settings are with same interest packets sending rate, same experiment time, and sequential content transmission behavior.
Bandwidth and Latency Aware Contribution Estimation in P2P Streaming System
(2014-09-01)
Ho, Cheng-Yun
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Huang, Ming-Hsiang
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Ho, Cheng-Yuan
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Tseng, Chien-Chao
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交大名義發表
In this article, a bandwidth and latency aware contribution estimation (BLACE) mechanism is proposed to enhance the efficiency of content distribution in a mesh peer-to-peer (P2P) streaming system. This is because the mesh P2P streaming system outperforms others in many aspects, but most content distribution mechanisms use only one of upload bandwidth and link latency as a factor, several contribution-aware schemes (CASs) just punish selfish peers, and some CASs only rearrange the content receiving order. Hence, the BLACE proposes a prevention way considering every peer\'s upload bandwidth, link latency, and the maximum playing delay of a stream at the same time to prioritize the content distribution. Moreover, BLACE is implemented on Coolstreaming with NS2 and experimental results show that BLACE could at the most shorten the receiving time about 15.44%, 13.94%, and 8.26%, and improve the whole performance about 7.05%, 2.81%, and 2.69% at the most, when it compares with the Coolstreaming, the Coolstreaming with bandwidth preference, and the Coolstreaming with latency preference, respectively.
Churn: a Key Effect on Real-World P2P Software
(2013)
Ho, Cheng-Yun
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Chung, Ming-Chen
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Yen, Li-Hsing
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Tseng, Chien-Chao
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資訊工程學系
Churn refers to a large number of arriving and departing participants within a short time in peer-to-peer (P2P) networks. This paper studies the impact of churn on real-world unstructured P2P networks. To this end, we need collecting snapshots of P2P network topology and associated performance metrics. Because P2P topology changes dynamically, the time to take a snapshot must be sufficiently short for the snapshots to be accurate. We propose Third-party-to-servent Crawling with Servent-to-servent Sampling (TCSS) system. TCSS uses a third-party crawling technique to collect network topology information without disturbing the original P2P network under investigation. Furthermore, TCSS adopts distributed and parallel techniques to speed up the crawling process. TCSS also employs a servent-to-servent sampling technique to gather the corresponding performance metrics of the P2P network simultaneously. Empirical results show that TCSS takes around 7 minutes to take a topology snapshot of the P2P network. Besides, we found that churn is indeed a combined effect of peer arrivals/departures and neighbor replacements. As the number of peers increases, the number of very long-lived peers remains nearly constant and the P2P network possesses a small-world property. Moreover, as churn aggravates, the average booting time of peers increases and the variation is proportional to the degree of churn. The response time of the top-rank keyword searches is not affected by the degree of churn.
Fast retransmit and fast recovery schemes of transport protocols: A survey and taxonomy
(2008-04-24)
Ho, Cheng-Yuan
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Chen, Yaw-Chung
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Chan, Yi-Cheng
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Ho, Cheng-Yun
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資訊工程學系
Although there are two standard transport protocols, TCP and UDP, offering services in the Internet, the majority of the traffic over the Internet is TCP-based. TCP-based applications can react to packet losses; however, many performance problems have been recently observed in the Internet. To resolve these problems, several new TCP fast retransmit and fast recovery algorithms have been proposed. This article surveys state-of-the-art fast retransmit and fast recovery mechanisms of TCP to address the lost packet problem, and presents a description of some useful algorithms, design issues, advantages, and disadvantages. The objective of this article is fourfold: to provide an introduction to TCP protocol; to discuss problems degrading TCP retransmission performance in the present-day Internet; to describe some proposed transport protocols that solve a number of throughput issues; and finally, to gain new insight into these protocols and thereby suggest avenues for future research. Based on our taxonomy, existing fast retransmit and fast recovery schemes of transport protocols are described in this survey. (C) 2008 Elsevier B.V. All rights reserved.
Improving performance of delay-based TCPs with rerouting
(2007-01-01)
Ho, Cheng-Yuan
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Chen, Yaw-Chung
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Ho, Cheng-Yun
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資訊工程學系
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Department of Computer Science
Delay-based TCPs detect network congestion in the early stage and successfully prevent periodic packet loss that usually occurs in loss-based mechanisms. It has been demonstrated that delay-based algorithms outperform loss-based schemes in many aspects. However, a delay-based TCP may not prevent unnecessary throughput degradation when rerouting occurs and in mobile IP networks and mobile ad hoe networks because it could not differentiate whether the increased RTT is due to route change or network congestion. This work investigates how to improve the performance of delay-based TCPs with rerouting and proposes a mechanism for delay-based TCPs. The proposed mechanism is able to re-measure the BaseRTT if necessary by detecting the change of TTL value of two end-hosts. Based on the simulation results, we demonstrate the effectiveness and utilities.
Performance Improvement of Delay-Based TCPs in Asymmetric Networks
(2011-03-01)
Ho, Cheng-Yuan
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Ho, Cheng-Yun
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Wang, Jui-Tang
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資訊工程學系
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Department of Computer Science
Delay-based TCPs detect network congestion in the early stage and successfully prevent periodic packet loss that usually occurs in loss-based TCPs. It has been demonstrated that delay-based algorithms outperform loss-based schemes in many aspects. However, a delay-based TCP may not prevent unnecessary throughput degradation in asymmetric networks and when the congestion occurs in the backward path over symmetric links. In this letter, we modify the mechanism of measuring RTT value for delay-based TCPs without clock synchronization. Based on the simulation results, we show the effectiveness and utilities.