• Title/Summary/Keyword: HOL 블록킹

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An Input-Buffered Dual-Banyan Switch with Multiple Switching Fabrics Based on Multistage Interconnection Networks (다단계 상호 연결망 기반의 다중 스위치 구조를 갖는 입력 버퍼형 이중 반얀 스위치)

  • Park, Sung-Won;Lee, Chang-Bum
    • The KIPS Transactions:PartC
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    • v.10C no.4
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    • pp.463-470
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    • 2003
  • Many types of switching fabrics have been proposed for use in ATM networks. Multistage Interconnection Networks (MINs) constitute a large class of ATM switching systems that are widely used in today´s internetworking. One of the most veil-known types of multistage networks is the banyan network. The banyan network is attractive for its simple routing scheme and low hardware complexity, but its throughput is very limited due to internal blocking and output contention. In this paper, we propose an input-buffered dual-banyan switch model with multiple switching fabric between switch input and output to avoid internal and Head-of Line blocking. By performance analysis and simulation, we show that our model has a lower ceil delay and 96% throughput which is much better than other banyan-type switch architecture.

Performance Improvement of the Multicast Switch using Output Scheduling Scheme (출력 스케줄링 기법을 이용한 멀티캐스트 스위치의 성능 개선)

  • 최영복;최종길;김해근
    • Journal of Korea Multimedia Society
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    • v.6 no.2
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    • pp.301-308
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    • 2003
  • In this paper, we propose a multicast ATM switch that reduces traffic load by using the method of storing unicast cells and multicast cells separately according to the type of the cells. The switch is based on a shared memory type to reduce HOL blocking and deadlock. In the proposed switch, we use a control scheme that schedules stored cells to output ports to reduce the loss of traffic cells and to output effectively. We analyzed the Performance of the proposed switch through the computer simulation and the results have shown the effectiveness of the switch.

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NDRR Algorithm for High Performance Queue Management (고성능 Queue 관리를 위한 NDRR 알고리즘)

  • Kim, Ji-Hoon;Min, Kyoung-Ju;Kwon, Taeck-Geun
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.06d
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    • pp.503-507
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    • 2007
  • 라우터는 여러 곳에서 들어오는 패킷들을 빠르게 전달하는 기능을 담당하는 네트워크 장비로서, 들어오는 패킷들이 공평하게 서비스 받을 수 있도록 큐 관리 알고리즘을 사용한다. 그런데 대부분의 라우터들은 HOL 블록킹 문제 때문에 버퍼를 입력 포트 쪽이 아닌 가상적으로 출력 포트 쪽에 정의하는 VOQ로 구현을 하였고, 패킷들이 공평하게 서비스 받기 위해 DRR 알고리즘으로 구현하는 경향이 있다. 이 논문에서는 기존의 DRR 알고리즘에서 패킷 서비스를 위한 경직된 조건에 유연성을 주어 기존의 DRR 알고리즘의 복잡도와 공평성을 유지하는 한편 패킷 서비스 성능을 높여주는 NDRR 알고리즘을 제안한다.

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Flow-Based WTP Scheduler for Proportional Differentiated Services in Wireless Communication Systems (무선통신 시스템에서의 비례지연서비스를 위한 플로우 기반 WTP 스케쥴러)

  • Park Hyosoon;Kwon Eunhyun;Kim Taehyoun;Lee Jaiyong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.7B
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    • pp.433-439
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    • 2005
  • In this paper, we propose a Flow Based Waiting Time Priority (FB-WTP) scheduler that supports the proportional delay differentiated services between classes. Existing scheduling algorithms utilize the configuration of scheduler, which is operated as class unit, applied to wired network. However, FB-WTP scheduler is operated as flow unit and can take advantage of multi-flow diversity effect in time-varying channel state environment. As a result, FB-WTP improves the average queueing delay on each class as well as supporting the average queueing delay ratio between classes. It also solves the HOL packet blocking problem implicitly. Simulation results show that FB-WTP scheduler has better system queueing delay performance than Look-ahead Waiting Time Priority (LWTP) scheduler and supports the larger queueing delay ratio between classes that network operator set.

An Effective Cell Scheduling Algorithm for Input Queueing ATM Switch (입력단 큐잉 방식의 ATM 스위치를 위한 효율적 셀 중재 방식에 관한 연구)

  • 김용웅;원상연;박영근
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.1A
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    • pp.122-131
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    • 2000
  • In this paper, we propose a cell scheduling algorithm for input queueing ATM switch. The input queueing architecture is attractive for building an ultra-high speed ATM (Asynchronous Transfer Mode) switch. We proposea WMUCS (Weighted Matrix Unit Cell Scheduler) based on the MUCS which resolves HOL blocking and outputport contention. The MUCS algorithm selects an optimal set of entries as winning cells from traffic matrix (weightmatrix). Our WMUCS differs from the MUCS in generating weight matrices. This change solves the starvationproblem and it reduces the cell loss variance. The performance of the proposed algorithm is evaluated by thesimulation program written in C++. The simulation results show that the maximum throughput, the average celldelay, and the cell loss rate are significantly improved. We can see that the performance of WMUCS is excellentand the cost-effective implementation of the ATM switch using proposed cell scheduling algorithm.

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Wireless Internet DiffServ Packet Scheduling Algorithm over Wireless Networks with Location-dependent Channel Errors (위치 종속적 채널 에러 특성을 갖는 무선망에서 인터넷 DiffServ QoS 제공을 위한 패킷 스케줄링 알고리즘)

  • 신강식;유상조
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.46-58
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    • 2003
  • The recent Internet is changing from its best-effort service and needs the network structure and traffic engineering, which can support various applications requiring differentiated traffic processing and high quality of service. The extension of the Internet from wired to wireless system generating location-dependent and burst errors make more difficult to support a good service with the existing packet scheduling algorithm. In this paper, we propose a wireless diffserv packet scheduling (WDSPS) algorithm that can provide reliable service in the differentiated wireless internet service network. The proposed scheduling algorithm solves the HOL(head of line) blocking problems of class queue occurred in wireless network, supports the differentiated service for each class which is defined in differentiated service networks and makes possible the gradual and efficient service compensation not only among classes but also among flows to prevent the monopoly of one class or one flow. Through simulations, we show that our proposed WDSPS scheduling algorithm can provide the required QoS differentiation between classes and enhance the service throughput in various wireless network conditions.