• Title, Summary, Keyword: GCRA

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Performance Analysis of GCRA Policing Algorithm for Constant-Bit Rate Service (항등비트율 서비스를 위한 GCRA 폴리싱 알고리즘의 성능 해석)

  • Kim, Young-Beom
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.12
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    • pp.2157-2165
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    • 2006
  • In implementing GCRA, well known as the representative user traffic policing algorithm for constant-bit rate service, it is essential to set proper values for delay variation tolerance in order to prevent network overload and excessive user data loss due to delay variation incurred inevitably during transmission process. In this paper, we investigate the performance of GCRA algorithm for various values of delay variation tolerance and suggest a guideline for setting proper delay variation tolerance values.

Performance of GFR service for TCP traffic in ATM switches with FIFO shared buffer (FIFO 공유 버퍼를 갖는 ATM 스위치에서 TCP 트래픽을 위한 GFR 성능 평가)

  • Park Inyong
    • Journal of the Korea Industrial Information Systems Research
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    • v.10 no.1
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    • pp.49-57
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    • 2005
  • ATM Form has defined the guaranteed frame rate (GFR) service to provide minimum cell rate (MCR) guarantees for TCP traffic in ATM networks and allow it to fairly share residual bandwidth. GFR switch implementation consists of the frame-based generic cell rate algorithm (F-GCRA) and a frame forwarding mechanism. The F-GCRA identifies frames that are eligible for an MCR guarantee. The frame forwarding mechanism buffers cells at a frame unit according to information provided by the F-GCRA and forwards the buffered cells to an output port according to its scheduling discipline. A simple GFR mechanism with shared buffer with a global threshold is a feasible implementation mechanism, but has been known that it is insufficient to guarantee the MCR. This paper has estimated performance of GFR service for TCP traffic over ATM switches with the simple FIFO-based mechanism

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Traffic Modeling and Call Admission Control GCRA-Controlled VBR Traffic in ATM Network (ATM 망에서 UPC 파라미터로 제어된 VBR 트래픽 모델링 및 호 수락 제어)

  • 정승욱;정수환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.7C
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    • pp.670-676
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    • 2002
  • The object of ATM network is to the guarantee quality of service(QoS). Therefore, various of traffic management schemes have been proposed. Among these schemes, call admission control(CAC) is very important to provide real-time services and ON-OFF model, which is single source traffic model, has been used. But ON-OFF model differ from GCRA(Generic Cell Rate Algorithm) controlled traffic in ATM network. In this paper, we analyze the traffic, which is controlled as dual GCRA, and propose TWM(Three-state Worst-case Model), which is new single source traffic model. We also proposed CAC to guarantee peak-to-peak CDV(Cell Delay Variation) based on the TWM. In experiments, ON-OFF model and TWM are compared to show that TWM is superior to ON-Off model in terms of QoS guaranteeing.

Improvement of F-GCRA Algorithm for ATM-GFR Service (ATM-GFR 서비스를 위한 F-GCRA 알고리즘 개선)

  • Park, In-Yong
    • The KIPS Transactions:PartC
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    • v.13C no.7
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    • pp.889-896
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    • 2006
  • ATM Forum has defined a guaranteed frame rate (GFR) service to serve Internet traffic efficiently. The GFR service provides virtual connections (VCs) for minimum cell rate (MCR) guarantees and allows them to fairly share the residual bandwidth. And ATM Forum has recommended a frame-based generic cell rate algorithm (F-GCRA) as a frame classifier, which determines whether an Am cell is eligible to use the guaranteed bandwidth in a frame level. An ATM switch accommodates cells in its buffer or drops them in a frame level according to current buffer occupancy. A FIFO shared buffer has so simple structure as to be feasibly implemented in switches, but has not been able to provide an MCR guarantee for each VC without buffer management based on per-VC accounting. In this paper, we enhance the F-GCRA frame classifier to guarantee an MCR of each VC without buffer management based on per-VC accounting. The enhanced frame classifier considers burstness of TCP traffic caused by congestion control algorithm so as to enable each VC to use its reserved bandwidth sufficiently. In addition, it is able to alleviate the unfairness problem in usage of the residual bandwidth. Simulation results show that the enhanced frame classifier satisfies quality of services (QoSs) of the GFR service for the TCP traffic.

Video 트래픽 제어를 위한 장면 전환의 검출 연구

  • 한승균;서덕영
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.155-159
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    • 1997
  • ATM(Asynchronous Transfer Mode)은 광대역망에서 여러 형태의 멀티미디어 서비스를 지원하는 수단을 제공한다. 요즘 통신망으로 ATM의 채택이 증가하고, 이 망들이 멀티미디어 통신을 하기 위해 많은 데이터들이 오고 갈 때, 영상을 효율적으로 트래픽 제어함으로써 통신망에 끼치는 영향을 최소화 할 수 있다. 본 연구에서는 장면 전환 검출에 관해 State(상태) 알고리즘, Standard deviation(표준편차) 알고리즘, Percentage(가중치) 알고리즘 등을 이용한 장면 전환 검출의 성능 시험을 했다. Stage 알고리즘은 n상태로 나누어서 이루어지고, Standard deviation 알고리즘은 통계적 측면을 다룬 것이고, Percentage 알고리즘은 비례에 의해 이루어진다. 그 중에 Percentage를 이용한 장면 전환 검출 알고리즘은 다른 알고리즘에 비해 능동적이고 효율적임을 보여 이를 제안한다. GCRA(Generic Cell Rate Algorithm)를 통해 트래픽 관련 파라미터의 지정에 관련한 Nonconforming 셀률에 의한 CDVT와 PCR의 분석을 시도한다. 이 때에도 마찬가지로 Percentage 알고리즘과 GCRA를 장면 전환 검출 데이터와의 상관관계를 통해 파라미터를 정하여 트래픽 관련 GCRA 알고리즘에 적용할 수 있다.

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A Study to Guarantee Minimum Bandwidth to TCP Traffic over ATM-GFR Service (ATM-GFR 서비스에서 TCP 트래픽의 최소 대역폭 보장에 관한 연구)

  • 박인용
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.4C
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    • pp.308-315
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    • 2002
  • Guaranteed frame rate (GFR) service has been defied to provide minimum cell rate (MCR) guarantees for virtual connections (VCs) carrying Internet traffic in ATM networks and allow them to fairly share residual bandwidth. The simplest switch implementation mechanism to support the GFR service in ATM networks consists of the frame-based generic cell rate algorithm (F-GCRA) frame classifier and the early packet discard (EPD)-like buffer acceptance algorithm in a single FIFO buffer. This mechanism is simple, but has foiled to guarantee the same bandwidth as an MCR to a VC that has reserved a relatively large MCR. This paper applies the packet spacing scheme to TCP traffic to alleviate its burstness, so as to guarantee a larger MCR to a VC. In addition, the random early detection (RED) scheme is added to the buffer acceptance algorithm in order to improve fairness in use of residual bandwidth. Simulation results show that the applied two schemes improve a quality of service (QoS) in the GFR service for the TCP traffic.

Problem over Upstream Channel in the TCP Connections of HFC/ATM Networks

  • Park, Sang-Jun;Park, Woo-Choo;Rhee, Byung-Ho
    • Proceedings of the IEEK Conference
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    • pp.505-508
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    • 2000
  • We discuss simulation results concerning the performance of the TCP protocol when running over high-speed HFC networks. Hybrid Fiber Coaxial are likely to provide fast and cost effective sup-port to a variety of applications including Video on demand, interactive computer games, and internet-type applications such as Webbrowsing, ftp, and telephony. Since most of these applications, use TCP as the transport later protocol, the key to their success largely depends on the effectiveness of the TCP protocol. In all simulation scenarios the TCP traffic is maxed with some background traffic whose level is taken as a variable parameter. Both the background traffic and TCP traffic are either unshaped, or shaped according to the GCRA algorithm. The effect of the background traffic on the TCP protocol performance is discussed varying the buffering capacity with nodes as well as the peak bit rate that each TCP connection is allowed to use.

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Traffic Shaper in consideration of UPC/NPC in ATM Networks (ATM망에서 UPC/NPC를 고려한 트래픽 정형화기)

  • 조태경;최병욱
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.12B
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    • pp.2003-2015
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    • 2000
  • 본 논문에서는 ATM 망을 구성하고 있는 노드(node) 간의 셀(cell) 전송시에 출력 링크(output link)로 전송된 셀이 수신 노드에서 수행하는 UPC/NPC에 의해 손실되지 않는 트래픽 정형화기(shaper)를 제안한다. 제안한 정형화기는 비실시간 가변비트율(nrt-VBR) 트래픽을 대상으로 한 것으로 각 ATM 연결(connection)에 대해 독립된 큐(queue)를 할당하였으며, 출력 링크로 전송할 셀을 저장하고 있는 큐를 선정하기 위해 모든 큐에 대해 Generic Cell Rate Algorithm(GCRA)를 수행하여 큐의 상태를 결정하고, 그 결과 전송 가능 상태에 있는 모든 큐들을 대상으로 본 논문에서 제안한 시간의존 확률적 스케줄링(time-dependent probability scheduling) 알고리즘을 적용하여 특정 큐를 선택하여 셀을 전송한다. 제안한 정형화기의 성능평가를 위해 WRR(Weighted Round Robin) 스케줄링 알고리즘을 사용한 정형화기 및 WFQ(Weighted Fair Queueing) 스케줄링 알고리즘을 적용한 정형화기에 대한 모의실험을 하였으며, 그 결과 제안한 정형화기는 비실시간 가변비트율(nrt-VBR) 트래픽의 정형화(shaping)에 우수한 성능을 나타냄을 확인하였다.

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