• Title, Summary, Keyword: RTT

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A Three-Color Marking Mechanism for Fairness Improvement in the Assured Service of the Diffserv Network (차등 서비스 네트워크의 확신 서비스에서 공평성 향상을 위한 3색 마킹 메커니즘)

  • 모상덕;정광수
    • Journal of KIISE:Information Networking
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    • v.30 no.6
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    • pp.764-775
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    • 2003
  • Previous works for the assured service in the Diffserv network have no sufficient consideration on the fairness of bandwidth share based on RTTs and the target rates of TCP flows. In this paper, in order to solve these problems, we propose a TRA3CM(Target rate and RTT Aware 3 Color Marking) mechanism. The TRA3CM mechanism provides three color marking and fair transmission rates among aggregate flows by considering RTT and target rate simultaneously. In case of higher target rate than bottleneck bandwidth, the TRA3CM mechanism is able to mitigate the RTT effect and provides fair transmission rates. In the results of comparing the performance among existing mechanisms and the TRA3CM, the TRA3CM mechanism was able to mitigate the RTT effect better than the former. The TRA3CM is shown to provide good performance for transmission rates proportional to various target rates.

A Study on Conversion Between UML and Source Code Based on RTT(Round-Trip Translator) (RTT(Round-Trip Translator) 기반의 UML과 소스코드 변환에 대한 연구)

  • Kim, Ji Yong;Cho, Han Joo;Kim, Young Jong
    • KIPS Transactions on Software and Data Engineering
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    • v.8 no.9
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    • pp.349-354
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    • 2019
  • s programming education becomes more important in recent years, it is necessary to learn how the source code written by students reflects Object-Oriented(OO) concepts. We present a tool called the Round-Trip Translator(RTT) that transforms the Unified Modeling Language(UML) class diagram and Java source code to provide a web-based environment that provides real-time synchronization of UML and source code. RTT was created by improving existing RTE and is a tool for students who are learning OO concepts to understand how their UML or source code reflects the concepts that user intended. This study compares the efficiency and user- friendliness of RTT with the existing Round-Trip Engineering-based tools. The results show that students have improved understanding of OO concepts through UML and source code translation by using the RTT. We also found out that students were satisfied with the use of the RTT, which provides more efficient and convenient user interface than the existing tools.

Measurement of End-to-End Forward/Backward Delay Variation (종단간 순방향/역방향 전송 지연 측정)

  • Hwang Soon-Han;Kim Eun-Gi
    • The KIPS Transactions:PartC
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    • v.12C no.3
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    • pp.437-442
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    • 2005
  • The measurement of RTT (Round Trip Time) can be used for the analysis of Internet congestion. However, simple measuring of RTT which measures only hun around time of a packet can not infer a packet forward/backward delay variation. In this thesis, we present a new algorithm which can be used for the estimation of forward/backward delay variation of packets. These delay variations are implication of network congestion state. In this algorithm, the reference forward/backward delay can be determined based on the minimum RTT value. The delay variation of each packet can be calculated by comparing reference delay with the packet delay. We verified our proposed algorithm by NS-2 simulation and delay measuring in a real network.

Measurement of RTT for TCP Congestion Control (TCP 혼잡제어를 위한 RTT(Round trip time) 측정)

  • Kim, Eun-Gi
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.5
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    • pp.1520-1524
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    • 2000
  • TCP congestion control algorithm prevents network congestion through the control of outgoing traffic size. The network, therefore, should monitor the incoming traffic size of a TCP to determine whether or not a TCP follows standard congestion control algorithms. Some TCP friendly test algorithms are proposed, But, these algorithms cannot be used in real environments because a router in a network does not know the RTT of a TCP flow. In this study, we propose a new RTT determination algorithm that can be used in a router. Our proposed algorithms is validated through the simulation studies.

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TCP Vegas RTT Ambiguity Problem and Its Solutions (TCP Vegas RTT Ambiguity 문제와 그 해결)

  • 김종덕;김종권
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.7B
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    • pp.1260-1269
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    • 2000
  • TCP 구현의 하나인 Vegas는 RTT 측정값을 바탕으로 혼잡을 인지하며 윈도우 크기 등 혼잡제어를 위한 주요 인자를 결정한다. 이러한 Vegas가 기존 TCP 구현에 비해 우수한 성능과 높은 공평성을 가짐은 여러 논문을 통해 보고되었다. 그런데 우리는 Vegas의 혼잡회피 방안이 TCP 데이터 흐름의 비대칭적 특성을 제대로 반영하지 못하며, 이것이 양쪽 방향 상태를 반영하는 RTT 측정값을 순방향 링크의 상태 해석에 이용하기 때문임을 발견하였다. 우리는 이를 Vegas RTT Ambiguity 문제라 하고, 네트워크 내의 패킷 스케쥴링 방법인 Small Get Priority Queue, TCP Timestamp Options을 이용한 수정 Vegas 구현 등 두 가지 해결 방안을 제시하였다. 우리는 시뮬레이션을 통해 Vegas RTT Ambiguity 문제와 제시한 해결 방안들을 검증하였다.

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Internet Roundtrip Delay Prediction Using the Maximum Entropy Principle

  • Liu, Peter Xiaoping;Meng, Max Q-H;Gu, Jason
    • Journal of Communications and Networks
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    • v.5 no.1
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    • pp.65-72
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    • 2003
  • Internet roundtrip delay/time (RTT) prediction plays an important role in detecting packet losses in reliable transport protocols for traditional web applications and determining proper transmission rates in many rate-based TCP-friendly protocols for Internet-based real-time applications. The widely adopted autoregressive and moving average (ARMA) model with fixed-parameters is shown to be insufficient for all scenarios due to its intrinsic limitation that it filters out all high-frequency components of RTT dynamics. In this paper, we introduce a novel parameter-varying RTT model for Internet roundtrip time prediction based on the information theory and the maximum entropy principle (MEP). Since the coefficients of the proposed RTT model are updated dynamically, the model is adaptive and it tracks RTT dynamics rapidly. The results of our experiments show that the MEP algorithm works better than the ARMA method in both RTT prediction and RTO estimation.

RTT based Password Authentication regarding Security and Usability (보안성과 유용성을 고려한 RTT기반의 패스워드 인증 방안)

  • 이희정;이금석
    • Proceedings of the Korean Information Science Society Conference
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    • pp.670-672
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    • 2003
  • 패스워드 인증방법은 온라인 사전 공격에는 약하다는 단점이 있음에도 달구하고, 사용하기에 가장 편리하다는 장점 때문에 오늘날 가장 일반적으로 사용되는 인증방법이다. 기존의 패스워드 인증방법처럼 편리하게 이용할 수 있으면서도 보다 보안성을 높이는 방안으로 RTT를 이용한 인증 프로토콜이 제안되어 왔다. RTT를 이용한 인증 프로토콜은 사용자가 아이디와 패스워드를 입력할 뿐만 아니라. 자동 프로그램 사람을 구별할 수 있는 질문에 응답하게 함으로써 자동 프로그램으로 공격하는 것을 막는다. 그러나 이 프로토콜에 이용되는 RTT의 여러 모델들에서 간단한 이미지는 공격 프로그램으로 공격 가능성이 있고, 복잡한 이미지는 사용자 입장에서 유용성이 취약함을 보인다. 따라서 이런 모델들의 취약성을 분석하여 공격에 대해서는 강하면서도 사용자들이 이용하기에는 편리하도록 하기 위해 새로운 모델을 제안하고, 보안성과 유용성을 고려한 RTT기반의 인증방안을 제안한다.

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Analysis of Factors Affecting RTT in Mobile Ad Hoc Networks (이동 애드 혹 네트워크에서 RTT에 영향을 주는 요인에 대한 분석)

  • Hwang, Jae-Hyun;Yoo, Hyuck
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.1469-1472
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    • 2004
  • 인터넷과 같은 안정된 네트워크에서는 RTT가 종단 시스템에서 네트워크의 상태 변화를 추정할 수 있게 해주는 유일한 정보이다. 따라서 많은 전송 계층 프로토콜들은 RTT를 기반으로 재전송 타임아웃 값이나 전송률 조절과 같은 중요한 결정을 내리고 있다 그러나 노드의 이동 가능성이 있고, 링크가 안정하지 않은 이동 애드 혹 네트워크에서는 RTT가 네트워크의 변화하는 상황을 정확히 반영하는 정보라 할 수 없다. 이 논문에서는 시뮬레이션 방법론을 이용하여 이동 애드 혹 네트워크에서 RTT에 영향을 주는 요인을 밝히고 그 정도를 분석하고자 한다.

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Long-Range Dependence and 1/f Noise in a Wide Area Network Traffic (광역 네트워크 트래픽의 장거리 상관관계와 1/f 노이즈)

  • Lee, Chang-Yong
    • Journal of KIISE:Information Networking
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    • v.37 no.1
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    • pp.27-34
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    • 2010
  • In this paper, we examine a long-range dependence in an active measurement of a network traffic which has been a well known characteristic from analyses of a passive network traffic measurement. To this end, we utilize RTT(Round Trip Time), which is a typical active measurement measured by PingER project, and perform a relevant analysis to a time series of both RTT and its volatilities. The RTT time series exhibits a long-range dependence or a 1/f noise. The volatilities, defined as a higher-order variation, follow a log-normal distribution. Furthermore, volatilities show a long-range dependence in relatively short time intervals, and a long-range dependence and/or 1/f noise in long time intervals. From this study, we find that the long-range dependence is a characteristic of not only a passive traffic measurement but also an active measurement of network traffic such as RTT. From these findings, we can infer that the long-range dependence is a characteristic of network traffic independent of a type of measurements. In particular, an active measurement exhibits a 1/f noise which cannot be usually found in a passive measurement.

One-Way Delay Estimation and Its Application (단방향 지연 시간 추정 기법과 이를 이용한 응용)

  • Choi Jin-Hee;Yoo Hyuck
    • Journal of KIISE:Information Networking
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    • v.32 no.3
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    • pp.359-369
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    • 2005
  • Delay estimation is a difficult Problem in computer networks. Accurate one-way delay estimation is crucial because it serves a very important role in network performance and thus application design. RTT(Round Trip Time) is often used as an approximation of the delay, but because it is a sum of the forward and reverse delays, the actual one-way delay cannot be estimated accurately from RTT. To estimate one-way delay accurately, this paper proposes a new scheme that analytically derives one-way delay, forward and reverse delay respectively. We show that the performance of TCP can improve dramatically in asymmetric networks using our scheme. A key contribution of this paper is that our one-way deiay estimation is much more accurate than RTT estimation so that TCP can quickly find the network capacity in the slow start phase. Since RTT is the sum of the forward and reverse delays, our scheme can be applied to any protocol that is based on RTT.