Browsing by Author "Ho, Cheng-Yuan"

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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.
A cross-layer approach for real-time multimedia streaming on wireless peer-to-peer ad hoc network
(2013-01-01)
Kuo, Jun-Li
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Shih, Chen-Hua
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Ho, Cheng-Yuan
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Chen, Yaw-Chung
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資訊工程學系
Peer-to-peer (P2P) live streaming over mobile ad hoc network (MANET) is a state-of-the-art technique for wireless multimedia applications, such as entertainments and disaster recovery. The peers share the live streaming over MANET via multi-hop wireless link, so an efficient data delivery scheme must be required. However, the high churn rate and the frequent mobility baffle the P2P membership management and overlay maintenance. The unreliable wireless connection of MANET leads to the difficulties of large-scale and real-time streaming distribution, and a lack of overlay proximity leads to the inefficient streaming delivery. We present a cross-layer design for P2P over MANET to manage and maintain the overlay, and select efficient routing path to multicast media streams. Our proposed scheme (COME-P2P) integrates both P2P DHT-based lookup and IPv6 routing header to improve the delivery efficiency. Through the cross-layer design, the low layer detects mobility for informing high layer to refine the finger table, and high layer maintains the efficient multicast path for informing low layer to refine the routing table. How to keep stable routing paths for live streaming via IPv6 routing is the main contribution of this paper. The overlay proximity can shorten routing propagation delay, and the hop-by-hop routing can avoid the traffic bottleneck. Through the mathematical analysis and simulation results, COME-P2P can be demonstrated to achieve high smoothness and reduce signaling overhead for live streaming. (C) 2012 Elsevier B.V. All rights reserved.
Advanced bootstrap and adjusted bandwidth for content distribution in peer-to-peer live streaming
(2015-05-01)
Kuo, Jun-Li
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Shih, Chen-Hua
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Ho, Cheng-Yuan
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Chen, Yaw-Chung
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資訊工程學系
Today peer-to-peer (P2P) systems have been deployed for various Internet multimedia applications such as live video streaming service. However, both peer churn and upload capacity insufficiency are inherent problems causing long start-up delay and unstable playback quality. Therefore, we introduce a scalable application-layer multicast algorithm, ABCD-P2P, which inherits the short end-to-end delay and low control overhead due to the push delivery scheme. The logical overlay is close to the physical topology (i.e., geographic proximity) in ABCD-P2P, so a short streaming multicast delivery path reduces the number of hops and avoids the network bottleneck or far routing. Both an advanced bootstrap mechanism and an adjusted bandwidth mechanism are suitable for the asymmetric bandwidth network. The mathematical analysis and simulation results demonstrate that our proposed scheme can achieve the goals of high playback smoothness, short start-up delay, short end-to-end delay, low control overhead, and short recovery time.
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.
Booting, browsing and streaming time profiling, and bottleneck analysis on android-based systems
(2013-07-01)
Lin, Ying-Dar
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Ho, Cheng-Yuan
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Lai, Yuan-Cheng
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Du, Tzu-Hsiung
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Chang, Shun-Lee
Android-based systems perform slowly in three scenarios: booting, browsing, and streaming. Time profiling on Android devices involves three unique constraints: (1) the execution flow of a scenario invokes multiple software layers, (2) these software layers are implemented in different programming languages, and (3) log space is limited. To compensate for the first and second constraints, we assumed a staged approach using different profiling tools applied to different layers and programming languages. As for the last constraint and to avoid generating enormous quantities of irrelevant log data, we began profiling scenarios from an individual module, and then iteratively profiled an increased number of modules and layers, and finally consolidated the logs from different layers to identify bottlenecks. Because of this iteration, we called this approach a staged iterative instrumentation approach. To analyze the time required to boot the devices, we conducted experiments using off-the-shelf Android products. We determined that 72% of the booting time was spent initializing the user-space environment, with 44.4% and 39.2% required to start Android services and managers, and preload Java classes and resources, respectively. Results from analyzing browsing performance indicate that networking is the most significant factor, accounting for at least 90% of the delay in browsing. With regard to online streaming, networking and decoding technologies are two most important factors occupying 77% of the time required to prepare a 22 MB video file over a Wi-Fi connection. Furthermore, the overhead of this approach is low. For example, the overhead of CPU loading is about 5% in the browsing scenario. We believe that this proposed approach to time profiling represents a major step in the optimization and future development of Android-based devices. (c) 2013 Elsevier Ltd. All rights reserved.
Calibrating parameters and formulas for process-level energy consumption profiling in smartphones
(2014-09-01)
Lin, Ying-Dar
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Rattagan, Ekarat
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Lai, Yuan-Cheng
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Chang, Li-Pin
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Yo, Yun-Chien
Battery-powered mobile devices substantially constrain energy resources. Process-level energy profiling tools can identify the most energy-consuming process and detail the energy usage of hardware components. With the help of energy profiling tools, programmers can fine-tune the energy consumption of processes to extend battery lifetime. However, profiling tools are highly dependent on hardware and must be calibrated for each hardware platform. Furthermore, for any new hardware components, new energy estimation formulas must be created. To solve these two problems regarding off-the-shelf products, this work proposes a two-phase calibrating approach. The first phase reconstructs the power table with a power meter, while the second creates new energy estimation formulas using linear regression analysis. The accuracy of the calibrated tool was evaluated in five scenarios and its error ratio is proven to be below 10%, occasionally less than 5%. Hence, this proposed approach to energy consumption profiling represents a major step in off-the-shelf devices. (C) 2014 Elsevier Ltd. All rights reserved.
Can: A context-aware NAT traversal scheme
(2013-07-01)
Tseng, Chien-Chao
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Lin, Chia-Liang
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Yen, Li-Hsing
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Liu, Jyun-Yan
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Ho, Cheng-Yuan
Network Address Translation (NAT) is a technique commonly used to share one public IPv4 address among several hosts located behind a NAT device. NAT devices typically block session requests originating from outside, causing NAT traversal problem that prevents the establishment of peer-to-peer (P2P) sessions. There have been many proposals for the NAT traversal problem. However, existing methods induce high connectivity check delay and resource demand when finding a communicating path, calling for a routine that determines the path best suited for a given pair of communicating peers. This study proposes CAN, a Context-Aware NAT traversal scheme which gathers and exchanges network-context information to find the most appropriate path for two communicating peers behind NAT devices. We have implemented CAN and conducted extensive experiments with off-the-shelf NAT devices to compare the performance of CAN with Interactivity Connectivity Establishment (ICE), the most acknowledged approach to creating a session across NATs. Experimental results show that CAN outperforms ICE in terms of direct communication ratio, connectivity check delay and message overload when checking connectivity. (c) 2013 Elsevier Ltd. All rights reserved.
CODE TCP: A competitive delay-based TCP
(2010-06-01)
Chan, Yi-Cheng
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Lin, Chia-Liang
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Chan, Chia-Tai
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Ho, Cheng-Yuan
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資訊工程學系
TCP Vegas is a well-known delay-based congestion control mechanism. Studies have indicated that TCP Vegas outperforms TCP Reno in many aspects. However, Reno currently remains the most widely deployed TCP variant in the Internet. This is mainly because of the incompatibility of Vegas with Reno. The performance of Vegas is generally mediocre in environments where it coexists with Reno. Hence, there exists no incentive for operating systems to adopt Vegas as the default transport layer protocol. In this study, we propose a new variant of Vegas called COmpetitive DElay-based TCP (CODE TCP). This variant is compatible with Reno and it can obtain a fair share of network resources. CODE is a sender-sided modification and hence it can be implemented solely at the end host. Simulations and experiments confirm that CODE has better fairness characteristics in network environments in which it coexists with Reno while retaining the good features of Vegas. (C) 2010 Elsevier B.V. All rights reserved.
Creditability-based weighted voting for reducing false positives and negatives in intrusion detection
(2013-11-01)
Lin, Ying-Dar
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Lai, Yuan-Cheng
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Ho, Cheng-Yuan
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Tai, Wei-Hsuan
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資訊工程學系
False positives (FPs) and false negatives (FNs) happen in every Intrusion Detection System (IDS). How often they occur is regarded as a measurement of the accuracy of the system. Frequent occurrences of FPs not only reduce the throughput of an IDS as FPs block the normal traffic and also degrade its trustworthiness. It is also difficult to eradicate all FNs from an IDS. One way to overcome the shortcomings of a single IDS is to employ multiple IDSs in its place and leverage the different capabilities and domain knowledge of these systems. Nonetheless, making a correct intrusion decision based on the outcomes of multiple IDSs has been a challenging task, as different IDSs may respond differently to the same packet trace. In this paper, we propose a method to reduce FPs and FNs by applying a creditability-based weighted voting (CWV) scheme to the outcomes of multiple IDSs. First, the CWV scheme evaluates the creditability of each individual IDS by monitoring its response to a large collection of pre-recorded packet traces containing various types of intrusions. For each IDS, our scheme then assigns different weights to each intrusion type according to its FP and FN ratios. Later, after their operations, the outcomes of individual IDSs are merged using a weighted voting scheme. In benchmarking tests, our CWV-based multiple IDSs demonstrated significant improvement in accuracy and efficiency when compared with multiple IDSs employing an ordinary majority voting (MV) scheme. The accuracy is the percentage of whole traces that are determined accurately, while the efficiency indicates that the voting algorithm performs better on reducing both FP and FN ratios. The CWV scheme achieved 95% accuracy and 94% efficiency while the MV scheme produced only 66% accuracy and 41% efficiency; the average percentages of FP/FN reduction were 21% and 58% respectively. (C) 2013 Elsevier Ltd. All rights reserved.
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.
Gallop-Vegas: An enhanced slow-start mechanism for TCP Vegas
(2006-09-01)
Ho, Cheng-Yuan
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Chan, Yi-Cheng
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Chen, Yaw-Chung
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資訊工程學系
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Department of Computer Science
In this article, we present a new slow-start variant, which improves the throughput of transmission control protocol (TCP) Vegas. We call this new mechanism Gallop-Vegas because it quickly ramps up to the available bandwidth and reduces the burstiness during the slow-start phase. TCP is known to send bursts of packets during its slow-start phase due to the fast window increase and the ACK-clock based transmission. This phenomenon causes TCP Vegas to change from slow-start phase to congestion-avoidance phase too early in the large bandwidth-delay product (BDP) links. Therefore, in Gallop-Vegas, we increase the congestion window size with a rate between exponential growth and linear growth during slow-start phase. Our analysis, simulation results, and measurements on the Internet show that Gallop-Vegas significantly improves the performance of a connection, especially during the slow-start phase. Furthermore, it is implementation feasible because only sending part needs to be modified.
How NAT-Compatible Are VoIP Applications?
(2010-12-01)
Lin, Ying-Dar
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Tseng, Chien-Chao
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Ho, Cheng-Yuan
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Wu, Yu-Hsien
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資訊工程學系
Today, the Internet is very diversified, further complicating the classic NAT traversal problems. In order to solve these problems, there are many proposed methods classified into two categories. One enhances the NAT traversal techniques of applications, and the other tries to modify the behavior of NATs. In this article we focus on the former because NATs have been installed, and their behavior cannot be altered through endpoint users. Accordingly, in order to test NAT traversal techniques of five VoIP applications (Skype, MSN, Google Talk, X-Lite, and Linphone), three network topologies have been designed with two endpoints behind the same, different, or multilevel NATs. Through a series of experiments and from the experiment results, we observe that these VoIP applications use some traversal techniques, such as NAT mapped-address probe, peer discovery, path check, and relay first, proposed by STUN, TURN, and ICE to make a direct connection when endpoints are behind the same or different NATs with independent mapping rules. However, with multilevel NATs, no endpoints can establish a direct connection when they use the above mentioned techniques, even if hairpin behavior is supported by NATs.
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.
Media-Independent Handover Design for Seamless Mobility in Heterogeneous WiMAX/Wi-Fi Networks
(2012-10-01)
Shih, Chen-Hua
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Kuo, Jun-Li
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Ho, Cheng-Yuan
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Chen, Yaw-Chung
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友訊交大聯合研發中心
As we are moving toward next generation wireless networks, we are facing the integration of heterogeneous access networks. The main challenge is to provide mobile users moving freely across different radio access technologies with satisfactory quality of services for a variety of applications. Consequently, the seamless roaming over heterogeneous networks is an important concern. To minimize the disruption to the ongoing session when a mobile user is moving from one access network to another, we propose a framework that integrates IEEE 802.11 WLANs and IEEE 802.16 WMANs based on the IEEE 802.21, so-called Media Independent Handover (MIH), to facilitate both homogeneous and heterogeneous handovers. Both numerical analysis and simulation results show that seamless roaming between WLAN and WMAN can be achieved and much better performance can be obtained compared with the IEEE 802.21 standard approach.
NAT-Compatibility Testbed: An Environment to Automatically Verify Direct Connection Rate
(2011-01-01)
Ho, Cheng-Yuan
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Wang, Fu-Yu
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Tseng, Chien-Chao
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Lin, Ying-Dar
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資訊工程學系
In this article, an NAT-compatibility testbed is designed to automatically conduct the repeated experiments, collect the test results, and verify the direct connection rate (DCR) of any NAT traversal programs. Achieving a high DCR is important because using relays may unnecessarily increase the bandwidth cost, processing load of the relay servers, and the end-to-end packet delay. The NAT-compatibility testbed is constructed with 4 components: two peers, an automatic execution mechanism, NAT devices, and signaling/intermediate servers such as STUN, TURN, and SIP. It is also called the fully meshed testbed because the test result of all NAT combinations is a square. It measures the DCR of ICE, KeyStone, and PJNATH as 53.7%, 59.87%, and 50.93%, respectively. Experimental results show that asymmetric and unexpected direct connectivity check results occur in the real Internet. In order to enhance NAT traversal capability, the findings, like "port prediction" and "call-role sensitivity problem," are also described in the experimental results.
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.
Quick Vegas: Improving performance of TCP Vegas for high bandwidth-delay product networks
(2008-04-01)
Chan, Yi-Cheng
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Lin, Chia-Liang
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Ho, Cheng-Yuan
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資訊工程學系
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Department of Computer Science
An important issue in designing a TCP congestion control algorithm is that it should allow the protocol to quickly adjust the end-to-end communication rate to the bandwidth on the bottleneck link. However, the TCP congestion control may function poorly in high bandwidth-delay product networks because of its slow response with large congestion windows. In this paper, we propose an enhanced version of TCP Vegas called Quick Vegas, in which we present an efficient congestion window control algorithm for a TCP source. Our algorithm improves the slow-start and congestion avoidance techniques of original Vegas. Simulation results show that Quick Vegas significantly improves the performance of connections as well as remaining fair when the bandwidth-delay product increases.
RING: A Cross-Layer P2P Group Conferencing Mechanism over Mobile Ad-Hoc Networks
(2012-09-01)
Kuo, Jun-Li
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Shih, Chen-Hua
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Ho, Cheng-Yuan
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Wang, Ming-Ching
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Chen, Yaw-Chung
In the infrastructure-less disaster environment, the application of the peer-to-peer (P2P) group conference over mdbile ad hoc network (MANET) can be used to communicate with each other when the rescue crews search the survivors but work separately. However, there still are several problems of in-time multimedia delivery in P2P-MANET: (I) MANET mobility influences the maintenance of P2P overlay. (2) P2P overlay is not proximal to MANET topology, this leads to the inefficient streaming delivery. (3) The unreliable wireless connection leads to the difficulty of multi-source P2P group conferencing. Therefore, P2P conferencing cannot work well on MANET To overcome the above disadvantages, in this paper, we present a cross-layer P2P group conferencing mechanism over MANET. called RING (Real-time Intercommunication Network Gossip). The RING uses the ring overlay to manage peers and utilizes the cross-layer mechanism to force the ring overlay to be proximal to MANET topology. Therefore. RING can lead efficient in-time multimedia streaming delivery. On the other hand, the ring overlay can deal with peer joining/leaving fast and simply, and improves the delivery efficiency with the minimum signaling overhead. Through mathematical theory and a series of experiments, we demonstrate that RING is workable and it can shorten the source-to-end delay with minimal signaling overhead.
Statistical Analysis of False Positives and False Negatives from Real Traffic with Intrusion Detection/Prevention Systems
(2012-03-01)
Ho, Cheng-Yuan
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Lai, Yuan-Cheng
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Chen, I-Wei
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Wang, Fu-Yu
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Tai, Wei-Hsuan
False positives and false negatives happen to every intrusion detection and intrusion prevention system. This work proposes a mechanism for false positive/negative assessment with multiple IDSs/IPSs to collect FP and FN cases from real-world traffic and statistically analyze these cases. Over a period of 16 months, more than 2000 FPs and FNs have been collected and analyzed. From the statistical analysis results, we obtain three interesting findings. First, more than 92.85 percent of false cases are FPs even if the numbers of attack types for FP and FN are similar. That is mainly because the behavior of applications or the format of the application content is self-defined; that is, there is not complete conformance to the specifications of RFCs. Accordingly, when this application meets an IDS/IPS with strict detection rules, its traffic will be regarded as malicious traffic, resulting in a lot of FPs. Second, about 91 percent of FP alerts, equal to about 85 percent of false cases, are not related to security issues, but to management policy. For example, some companies and campuses limit or forbid their employees and students from using peer-to-peer applications; therefore, in order to easily detect P2P traffic, an IDS/IPS is configured to be sensitive to it. Hence, this causes alerts to be triggered easily regardless of whether the P2P application has malicious traffic or not. The last finding shows that buffer overflow, SQL server attacks, and worm slammer attacks account for 93 percent of FNs, even though they are aged attacks. This indicates that these attacks always have new variations to evade IDS/IPS detection.
TCP-Ho: A congestion control algorithm with design and performance evaluation
(2007-03-01)
Ho, Cheng-Yuan
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Chan, Yi-Cheng
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Chen, Yaw-Chung
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資訊工程學系
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Department of Computer Science
A critical design issue of Transmission Control Protocol (TCP) is its congestion control that allows the protocol to adjust the end-to-end communication rate based on the detection of packet loss. However, TCP congestion control may function poorly during its slow start and congestion avoidance phases. This is because TCP sends bursts of packets with the fast window increase and the ACK-clock based transmission in slow start, and respond slowly with large congestion windows especially in high bandwidth-delay product (BDP) networks during congestion avoidance. In this article, we propose an improved version of TCP, TCP-Ho, that uses an efficient congestion window control algorithm for a TCP source. According to the estimated available bandwidth and measured round-trip times (RTTs), the proposed algorithm adjusts the congestion window size with a rate between exponential growth and linear growth intelligently. Our extensive simulation results show that TCP-Ho significantly improves the performance of connections as well as remaining fair and stable when the BDP increases. Furthermore, it is feasible to implement because only sending part needs to be modified.