• Title/Summary/Keyword: Output queueing

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Advanced Pipelined Heap Architecture for Output Queueing Switches (고속 네트워크 스위치에서의 QoS보장을 위한 아웃풋 큐 구조)

  • 김성원;김종권
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.10c
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    • pp.254-256
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    • 2000
  • 본 논문에서는 여러 단계의 QoS(Quality of Service)를 지원하면서 빠르고 확장이 용이하며 각종 패킷 폐기(packet drop) 방식을 지원하는 평형 파이프라인 우선순위 아웃풋 큐 구조(balanced pipelined priority output queue architecture)를 제시하고 있다. 본 방안은 기존에 연구된 파이프라인 우선순위 힙(pipelined heap, P-heap)[1]을 기반으로 하고 있다. 파이프라인 우선순휘 힙은 우선순위에 따라 패킷을 전송하는 작업을 파이프라인 방식으로 처리하여 처리 성능을 향상시킨 아웃풋 큐 구조이다. 그러나 P-heap은 평형성(balance) 문제를 전혀 고려하고 있지 않으며, 다양한 패킷 폐기 방안을 제공하고 있지 못하다. 본 논문에서는 이런 측면에서 P-heap을 개선한 Advanced P-heap을 제안하고 있다. Advanced P-heap은 평균적인 상황에서 힙에 평형성을 부여하고, 각종 패킷 폐기 정책을 지원할 수 있는 일반적인 우선순위별 차별 패킷 구조를 제시하고 있다.

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Performance Evaluation of Output Queueing ATM Switch with Finite Buffer Using Stochastic Activity Networks (SAN을 이용한 제한된 버퍼 크기를 갖는 출력큐잉 ATM 스위치 성능평가)

  • Jang, Kyung-Soo;Shin, Ho-Jin;Shin, Dong-Ryeol
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.8
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    • pp.2484-2496
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    • 2000
  • High speed switches have been developing to interconnect a large number of nodes. It is important to analyze the switch performance under various conditions to satisfy the requirements. Queueing analysis, in general, has the intrinsic problem of large state space dimension and complex computation. In fact, The petri net is a graphical and mathematical model. It is suitable for various applications, in particular, manufacturing systems. It can deal with parallelism, concurrence, deadlock avoidance, and asynchronism. Currently it has been applied to the performance of computer networks and protocol verifications. This paper presents a framework for modeling and analyzing ATM switch using stochastic activity networks (SANs). In this paper, we provide the ATM switch model using SANs to extend easily and an approximate analysis method to apply A TM switch models, which significantly reduce the complexity of the model solution. Cell arrival process in output-buffered Queueing A TM switch with finite buffer is modeled as Markov Modulated Poisson Process (MMPP), which is able to accurately represent real traffic and capture the characteristics of bursty traffic. We analyze the performance of the switch in terms of cell-loss ratio (CLR), mean Queue length and mean delay time. We show that the SAN model is very useful in A TM switch model in that the gates have the capability of implementing of scheduling algorithm.

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ASYMPTOTIC MAXIMUM PACKET SWITCH THROUGHPUT UNDER NONUNIFORM TRAFFIC

  • JEONG-HUN PARK
    • Management Science and Financial Engineering
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    • v.4 no.2
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    • pp.43-58
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    • 1998
  • Packet switch is a key component in high speed digital networks. This paper investigates congestion phenomena in the packet switching with input buffers. For large value of switch size N, mathematical models have been developed to analyze asymptotic maximum switch throughput under nonuniform traffic. Simulation study has also been done for small values of finite N. The rapid convergence of the switch performance with finite switch size to asymptotic solutions implies that asymptotic analytical solutions approximate very closely to maximum throughputs for reasonably large but finite N. Numerical examples show that non-uniformity in traffic pattern could result in serious degradation in packet switch performance, while the maximum switch throughput is 0.586 when the traffic load is uniform over the output trunks. Window scheduling policy seems to work only when the traffic is relatively uniformly distributed. As traffic non-uniformity increases, the effect of window size on throughput is getting mediocre.

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An Algorithm to Determine the Spare Inventory Level of Finite Repairable-item Inventory System with Finite Number of Operating Items (유한가동제품을 가진 수리가능시스템의 여유제품수준의 결정)

  • Shin, Kyu-Chul;Kim, Jong-Soo;Hur, Sun
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.21 no.48
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    • pp.15-23
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    • 1998
  • This paper concerns the problem of determining the spare inventory level for multi-echelon repairable-item inventory system with finite number of operating items. We consider the system which has several bases and a central depot. When an item fails, it is dispatched to a repair facility and, a spare, if available, is plugged in immediately. When the failed item is repaired, it is sent to the base and either is used to fill a backorder or is stored at a spare inventory point. Using queueing network, we develop an algorithm to find the spare inventory level which minimizes the total expected cost and, simultaneously, satisfies a specified minimum fill rate. The results of the algorithm clearly indicate that the algorithm successfully generate output with optimal solution.

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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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Pipelined and Prioritized Round Robin Scheduling in an Input Queueing Switch (입력큐 교환기에서의 우선순위 파이프라인 순환 스케줄링)

  • 이상호;신동렬
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.6
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    • pp.365-371
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    • 2003
  • Input queued switch is useful for high bandwidth switches and routers because of lower complexity and fewer circuits than output queued. The input queued switch, however, suffers the HOL-Blocking, which limits its throughput to 58%. To overcome HOL-Blocking problem, many input-queued switch controlled by a scheduling algorithm. Most scheduling algorithms are implemented based on a centralized scheduler which restrict the design of the switch architecture. In this paper, we propose a simple scheduler called Pipelined Round Robin (PRR) which is intrinsically distributed by each input port. We presents to show the effectiveness of the proposed scheduler.

Performance Analysis of Mobile Exchange Control Part with Simulation (시뮬레이션에 의한 이동통신 교환기 제어계의 성능 분석)

  • 이일우;조기성;임석구
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.10
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    • pp.2605-2619
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    • 1996
  • In this paper, we evaluated performance of mobile exchange control part. Queueing network model is used for modeling of mobile exchange control part. We developed a call control processing and location registration scenartio which has a message exchange function between processors in mobile exchange control part. A network symbol are used the simulation models that are composed of the initialization module, message generation module, message routing module, message processing module, message generation module, HIPC network processing module, output analysis module. as a result of computer simulation, we obtain the processor utilization, the mean queue length, the mean waiting time of control part based on call processing and location registration capacity. The call processing and location registration capacity is referred by thenumber of call attempts in the mobile exchange and must be satisfied with the quality of service(delay time).

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A Study on New Cell Switch Fabric for Increasing the Performance of ATM Switching Systems (ATM 교환 시스템의 성능향상을 위한 새로운 셀 스위치 구조 연구)

  • 정진태;이옥재;전병실
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.3
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    • pp.12-23
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    • 1997
  • In this paper, we propose a new cell switch fabric for increasing the performance of ATM switching systems. Proposed switching network consists of a sorting network and a routing network. Both of these are multistage networks where each stage performs a fixed permutation on the incoming lines, and then routes them through a clumn of 2x2 switching elements. It is designed for distributing inputs and parallel processing to reduce the hardware complexity and obtain high performance of switching network. The structure and the operation of th eswitching network aredescribed and the performanceof the switching network is anlyzed under uniform traffic models. In this result, though the size of proposed network is increased the large scale, it has always the same throughput as the that of genral output queueing system with N=2. So, it is found that our proposed network is appropriate for the high apeed and lrger size of ATM switching systems.

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A Simulation Study on Efficiency of Container Crane in Container Terminal (컨테이너 터미널에서 컨테이너 크레인의 하역능력 추정에 관한 시뮬레이션 연구)

  • Yun, Won-Young;Choi, Yong-Seok;Song, Jin-Young;Yang, Chang-Ho
    • IE interfaces
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    • v.14 no.1
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    • pp.67-78
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    • 2001
  • This paper describes the simulation study which estimates the container crane efficiency in container terminal. In most simulation studies, it is assumed that container cranes are available at any time. Though the failures of container cranes don't occur often, they are very serious problems on terminal efficiency. As usual, the failures of container crane cause arrived ships to delay the departure time. In this study, a queueing simulation model for container terminal, which focuses on the failures of container cranes, is designed. The simulation approach appears to be the most appropriate one because it allows to avoid the usual exponential assumption on interarrivals of ships and service times of container cranes. Using the developed model, we tested the efficiency of container cranes considering failures with a real system size and performed the simulation experiment on real container terminal to validate the developed simulation model. The results of simulation experiment were analyzed using output statistics, which include the waiting times of vessels and yard tractors, the utilization for container cranes, and the berth occupancy rates.

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A Study on Real Time and Non-real Time Traffic Multiplexing with Congestion Control (폭주제어를 포함한 실시간 및 비실시간 트래픽의 다중화에 관한 연구)

  • 송관호;이재호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.4
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    • pp.750-760
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    • 1994
  • In this paper we proposed a multiplexing scheme of real time and non-real traffics in which a congestion control is embedded. Real time traffics are assumed to be nonqueuable and have preemptive priority over non-real time traffics in seizing the common output link, whereas the non-real time traffics wait in the common buffer if the output link is not available for transmission. Real time traffics are encoded according to the bandwidth reduction strategy, paticularly when congestion occurs among non-real time traffics. This scheme provides us an efficient way for utilizing the costly bandwidth resources, by accommodation as many real time traffics as possible with gauranteeing its mimimum bandwidth requirements, and also resloving the congestion encountered among non-real time traffics. We describe the system as a Markov queueing system, provide the analysis by exploiting the matrix geometric method, and present the performance for various performance measures of interest. Some numerical results are also provided.

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