• Title/Summary/Keyword: TCP throughput

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Performance Improvement of the Drop Policy based on TCP Retransmission in Optical Burst Switched Networks (OBS망에서의 TCP 재전송을 고려한 Drop Policy의 성능 향상)

  • 김래영;김현숙;김효진;송주석
    • Proceedings of the Korean Information Science Society Conference
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    • 2003.10c
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    • pp.1-3
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    • 2003
  • OBS망에서 버스트의 충돌로 인한 버스트의 drop은 TCP의 성능에 중요한 영향을 끼치나, 기존의 drop policy에서는 이를 고려하지 않으며 TCP에 대한 연구로는 버스트의 assembling이 주를 이루고 있다. 본 논문에서는 OBS망에서 TCP의 재전송 문제를 drop policy와 연계하여 그 성능을 향상시키고자 한다. 본 논문에서 제안하는 drop policy는 버스트의 재전송 횟수가 더 작은 버스트를 drop시키는 TCP 기반 DP이다. TCP 기반 DP 모델과 일반적인 DP 모델의 성능을 ns­2를 이용한 시뮬레이션을 통해 평가하며, 이 때 시간의 변화에 따른 TCP throughput과 패킷의 drop rate을 비교 분석한다.

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Performance Evaluation of PEP based TCP Splitting Scheme in Satellite Communication Systems (위성 통신 시스템에서 TCP연결 분할 기반 PEP의 성능 평가)

  • Weldegiorgis, Nathnael Gebregziabhe;Lee, Kyu-Hwan;Kim, Jong-Mu;Kim, Jae-Hyun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.8
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    • pp.10-17
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    • 2015
  • A satellite communication system is one of viable solutions for Internet applications running in wide areas. However, the performance of TCP can be seriously degraded in the satellite networks due to long round-trip time (RTT) and high bit error rate (BER) over satellite links. Therefore, a performance enhancing proxy(PEP) based TCP splitting connection scheme is used in the satellite link to improve the TCP performance. In this paper, we implement PEP testbed and conduct experiment to evaluate the performance of TCP splitting connection by comparing with high-speed TCP solutions in various environments. In our experimental environment, we consider multiple connections, high packet loss, and limited bandwidth. The experiment results show that PEP improves the TCP throughput than high-speed TCP variants in various environments. However, there is no improvement of the TCP throughput with the limited bandwidth because there is packet loss caused by both the congestion and the channel error.

A TCP Fairness Guarantee Scheme with Dynamic Advertisement Window Adjustment for Mobile Broadband Wireless Access Networks (이동 광대역 무선 접속 네트워크에서 동적 Advertisement Window 조절을 통한 TCP Fairness 보장 기법)

  • Kim, Seong-Chul;Cho, Sung-Joon
    • Journal of Advanced Navigation Technology
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    • v.12 no.2
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    • pp.154-163
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    • 2008
  • In a mobile broadband wireless access (MBWA) network, many users access a base station (BS), which relays data transferred from high-speed wired network to low-speed wireless network. For this difference of their data rate, a BS suffers from the lack of its buffer space when many users run multiple applications at the same time, and thus packet losses occur. TCP, which guarantees end-to-end reliability, is used as transport protocol also in wireless networks. But TCP lowers their transmission rate incorrectly and frequently whenever packet losses occur. And they increase their transmission rate differently with each other; finally TCP throughput of each TCP flow varies largely, and then TCP fairness goes worse. In this paper, a scheme that controls packet transmission rate adaptively according to TCP flows' transmission rate, that prevents buffer overflows at BS, and that guarantees TCP fairness at a certain degree is proposed. As it is analyzed by simulations, the proposed scheme enhances TCP fairness by maintaining TCP throughput of each TCP sender similarly with each other.

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A Study on Bandwidth and Buffer Management Mechanisms of IP Networks (IP 네트워크의 대역폭 및 버퍼 관리 메커니즘에 관한 연구)

  • Hai, Hoang Dang;Thuong, Pham Van;Hong, You-Sik
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.2
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    • pp.143-149
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    • 2010
  • Bandwidth and Buffer are critical network resources to determine the end-to-end quality of service. In this paper, we investigate several techniques on bandwidth and buffer management and classify them according to the types they used for controlling the throughput of a TCP/IP network. Moreover, in this paper, it present a new approach for modeling the active bandwidth and buffer control mechanisms for TCP/IP networks.

A Rate-Based Buffer Management Algorithm to Improve TCP Performance over ATM networks (ATM 네트워크에서 TCP 성능향상을 위한 평균 전송율 기반의 버퍼관리 알고리즘)

  • 김관웅;이창기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.2B
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    • pp.263-271
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    • 2004
  • In this paper, we proposed a new buffer management algorithm using perVC-Queuing discipline. Proposed algorithm uses service rate estimation and assigns dynamic perVC threshold to each VCs. Service rate estimation and dynamic perVC threshold combined with global threshold provide nearly optimal throughput and improve fairness performance of network resource among GFR VCs as well as guarantee MCR of all VCs. From simulation results, we demonstrate the proposed scheme fulfills the requirement of GFR service as well as improves the TCP throughput.

Effects of Retransmission Timeouts on TCP Performance and Mitigations: A Model and Verification (재전송 타임아웃이 TCP 성능에 미치는 영향과 완화 방안들의 모델링을 통한 성능 분석)

  • 김범준;김석규;이재용
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.7B
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    • pp.675-684
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    • 2004
  • There have been several efforts to avoid unnecessary retransmission timeouts (RTOs), which is the main cause for TCP throughput degradation. Unnecessary RTOs can be classified into three groups according to their cause. RTOs due to multiple packet losses in the same window for TCP Reno, the most prevalent TCP version, can be avoided by TCP NewReno or using selective acknowledgement (SACK) option. RTOs occurring when a packet is lost in a window that is not large enough to trigger fast retransmit can be avoided by using the Limited Transmit algorithm. In this Paper, we comparatively analyze these schemes to cope with unnecessary RTOs by numerical analysis and simulations. On the basis of the results in this paper, TCP performance can be quantitatively predicted from the aspect of loss recovery probability. Considering that overall performance of TCP is largely dependent upon the loss recovery performance, the results shown in this paper are of great importance.

Adaptation Latency and Throughput of TCP Congestion Control Schemes on Vertical Handoff (이기종망간의 핸드오프에 대한 TCP 적응성능 분석연구)

  • Seok, Woo-Jin;Lee, Gil-Jae;Kwak, Jai-Seung;Kim, Sang-Ha
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.2B
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    • pp.124-132
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    • 2007
  • Where a wireless LAN and a cellular network coexist, a mobile node has to experience vertical handoffs to move between them. Immediately after the vertical handoffs, TCP must need adaptation latency to adjust its congestion window to the proper size at a newly arrived network to use full of a new end-to-end available bandwidth. Even though SACK TCP has the best performance among other regular TCPs in the previous studies, it still cannot use full of the new available bandwidth quickly due to its inefficient increasing way of congestion window. BIC TCP, that becomes a popular TCP in long fat networks, has great feature working well against vertical handoffs by increasing congestion window exponentially with TCP connection sustained. In this paper, we derive adaptation latency of SACK TCP and BIC TCP numerically, and verify them by simulations. We also find that the shorter adaptation latency of BIC TCP produces higher throughput than SACK TCP on vertical handoffs. Consequently, to get higher performance on vertical handoff situations, we propose to use BIC TCP.

TCP-Friendly Rate Control for Vertical Handover over Wireless Heterogeneous Network (무선 이종망 환경에서 Vertical Handover를 위한 TCP-Friendly 비트율 제어)

  • Pyun, Jae-Young
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.45 no.2
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    • pp.33-40
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    • 2008
  • Streaming video has become a popular form of transferring media over the wired/wireless network. TCP-friendly rate control (TFRC) is used as a streaming media transport protocol. Using the TCP congestion response function and current network conditions, TFRC adjusts its sending rate to yield the maximum TCP-friendly throughput. Since TFRC was designed for applications that would prefer to maintain a slowly-changing sending rate, it is less responsive to changes in handover between wireless heterogeneous networks such as 3G network, WLAN, and so on. This paper shows a new TFRC method for vertical handover over wireless heterogeneous network. The proposed TFRC method has features of low quality interruption and fast rate adaptation to a new target network. The simulation results show that the proposed one provides better QoS and throughput support than the traditional TFRC scheme during vertical handover.

A Study on Improving TCP Performance over ABR/UBR Services in ATM Network (ATM 망에서 ABR/UBR 서비스상의 TCP 성능 향상에 관한 연구)

  • 김명희;박승섭
    • Journal of Internet Computing and Services
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    • v.1 no.2
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    • pp.1-10
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    • 2000
  • ATM network technology is generally used for the solution of integrating multimedia service in high-speed Internet. In Internet protocol based on ATM services, If single cell is lost in ATM layer, the entire TCP packet will be lost. Therefore, TCP performance will be degraded. In order to reduce cell loss, when congestion occur, UBR+EPD mechanism is proposed to improve the throughput in TCP over UBR, and ER scheme is suggested in TCP over ABR. In this paper, we analyzed the performance improvement effect of UBR+EPD with FRR (Fast Retransmission and Recovery), the adjusting EPD threshold parameter (R), and variation of MTU (Maximum Transport Unit) size. As a result, through the analysis of performance, we know that the improved throughput and fairness are shown by the proposed scheme.

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A Traffic Conditioning Mechanism for Enhancing the Fairness of TCP and UDP Flows (TCP 와 UDP 흐름의 공평성 향상을 위한 트래픽 조절 메커니즘)

  • Lee, Sung-Keun
    • The Journal of Korean Association of Computer Education
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    • v.7 no.1
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    • pp.37-44
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    • 2004
  • Differentiated services network (DiffServ) aims to provide the same service to a group of connections that have similar Quality of Service requirements. One of the essential function to realize DiffServ is the traffic conditioning mechanism. The paper proposes the enhanced traffic conditioning mechanism which can assure the reserved rates of TCP and UDP flows and support fair distribution of excess bandwidth. The simulation results show that the new mechanism is rather insensitive of the effect of UDP against TCP throughput, and performs better both in terms of throughput assurance and fair distribution of excess bandwidth in case of well-provisioned and over-provisioned network environment.

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