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1.
张鹏  俞柏锋  庞琳  张兴明 《计算机应用》2008,28(7):1831-1834
根据大规模接入汇聚路由器(ACR)的总体技术规范,IPTV组播复制在ACR的以太网分合路器(EMD)中进行,而IPTV组播业务的增长会对其他业务造成冲击,因此需要对IPTV组播流量进行控制,以保证其他业务的带宽分配,针对IPTV流量控制中的关键环节──队列调度,提出了一种公平服务多维轮询调度策略(FSMWRR),性能仿真的结果表明该调度策略能够满足IPTV业务的低时延、时延抖动的需求,同时保证各个业务带宽分配的公平性。  相似文献   

2.
Video loss recovery with FEC and stream replication   总被引:2,自引:0,他引:2  
Packet loss is inevitable in video multicast. In this paper, we propose and study an effective feedback-free loss recovery scheme for layered video which combines forward error correction (FEC) and stream replication. In our scheme, the server multicasts the video in parallel with FEC packets and a number of replicated delayed (ReD) version of the stream. Receivers autonomously and dynamically join the FEC and ReD streams to repair their losses. On the server side, we analyze and optimize the number of replicated streams and FEC packets to meet a certain residual loss requirement (i.e., error after correction). On the receiver side, we analyze the optimal combination of FEC and ReD packets to minimize its loss. We also present a fast yet accurate approximation algorithm for receiver to make such decision. We show that FEC combined with merely one or two replicated streams can effectively reduce the residual error rate (by as much as 50%) as compared with pure FEC or replication alone. Both subjective and objective video measures confirm that our recovery scheme achieves much better visual quality.  相似文献   

3.
基于应用层负载均衡策略的分析与研究   总被引:2,自引:0,他引:2       下载免费PDF全文
介绍了Round Robin(RR),Weighted Round Robin(WRR),Least Connection(LC)和Weighted Least Connection(WLC)四种负载均衡算法,对这四种算法进行性能仿真。根据模拟得到的相关数据绘制各个算法的负载均衡度性能曲线,并对每个算法进行了性能分析。在此基础上设置三种不同的模拟模型,对四种算法进行更深入的测试和性能比较。  相似文献   

4.
在WRR(WeightedRoundRobin,带权重的循环)算法的基础上,提出了一种适应无线局 域网特点的实时业务的调度算法。该算法工作在数据链路层,和无线局域网的介质访问控制(MAC) 层协议DCF(DistributedCoordinateFunction)紧密结合,有效避免了对列头部阻塞问题,提高了信道利 用率。通过采用补偿机制,近似达到了长期公平性。使用NS(NetworkSimulator)仿真进行性能评价, 结果表明该算法能有效提高实时业务的端端吞吐率,降低端端延迟和丢包率,延迟抖动也较小,可以 在一定程度上保证实时业务的服务质量。  相似文献   

5.
基于多输出端口的简单高效的交换结构   总被引:2,自引:2,他引:0       下载免费PDF全文
基于并行存储机制构建高性能PMS交换结构,采用流模型证明在不加速的情况下,PMS交换结构对满足强大数定律的可容许到达业务能实现100%的吞吐量。基于该交换结构,提出支持分组且具有多个输出端口的最短队列优先轮询算法SQF-RR。仿真结果表明,应用该算法的PMS交换结构能获得较好的性能。  相似文献   

6.
唐权  高志江 《计算机工程》2011,37(7):118-120
通过研究4种经典的CICQ调度算法,提出一种高性能的LQF_DRR交换调度算法。该算法在输入端采用最长队列优先调度策略,在输出端采用DRR调度机制,通过输入端与输出端的相互配合,优先服务异常队列,以减小交换结构输入端长队列对算法性能的影响。仿真结果证明该算法在各种流量下都有良好的时延性能和稳定性。  相似文献   

7.
针对传统的物理集群系统无法灵活应对大型互联网应用的问题,提出一种云环境下虚拟机集群的综合负载均衡机制。该方法首先定期地采集集群中虚拟机节点的CPU、内存、连接数、响应时间,以及所在物理主机的负载状况等指标信息,然后加权计算节点的综合负载并得出其权值,最后通过调度器进行任务请求的合理分配,从而解决了传统集群系统负载不均且不能适应多变的网络环境等诸多问题。实验结果表明,与加权轮询法(WRR)和加权最少连接法(WLC)调度方案相比,该机制能够在并发量较大时维持较低的响应时间,并能够根据集群中综合负载的状态实时地增加或减少虚拟机数量,通常在5s之内达到整体集群的负载均衡。  相似文献   

8.
首先概述了在网络管理系统中探测网络拓扑的一般方法,然后根据GPON系统的结构特点,设计了基于SNMP协议的无源光网络中显示OLT和ONU拓扑结构的方案,并采用C++编写了网络管理端的探测显示模块,最后通过代理端的模拟收发系统,实现了网络管理站通过OLT代理实时发现ONU拓扑以及状态的功能.  相似文献   

9.
Ethernet Passive Optical Networks (EPONs) are regarded as an important technology for current access networks. However, EPONs perform poorly in differentiated service environments, and may therefore fail to meet the Quality of Service (QoS) demands of emerging triple-play services (i.e. Voice over IP, video and BE traffic). Accordingly, the present study proposes a novel Dynamic Bandwidth Allocation (DBA) scheme, designated as Frame-Oriented Interleaved Polling with Adaptive Cycle Time (FIPACT), to improve the differentiated QoS capability of EPON networks. In the proposed scheme, the Optical Line Terminal (OLT) divides the time domain of the upstream network bandwidth into a contiguous series of fixed-length frames. Within each frame, each Optical Network Unit (ONU) is guaranteed sufficient network resources to transmit a specific quota of each triple-play service. In this manner, the proposed DBA scheme can satisfy the differentiated QoS requirements of triple-play services. Therefore, based on the M/G/1 queueing analysis framework of multiuser cyclic polling systems, this study develops an analytical framework to derive the closed-form expressions for FIPACT mean packet delay. The simulation results validate the analytical results and confirm the efficiency and effectiveness of the proposed DBA scheme.  相似文献   

10.
Passive Optical Networks (PONs) are widely adopted as the last-mile technology due to the large bandwidth capacity it provides to end users. In addition, PON is viewed as a green access technology since it reduces energy consumption compared to other access technologies (e.g. Fiber to the Node). However, there is still room for enhancing the energy efficiency of PON further, and we can find many attempts along those lines in academia and industry. A widely used approach to save energy in Time Division Multiplexing (TDM)-PON is to keep the Optical Network Units (ONUs) in sleep mode when they do not have anything to receive or transmit. However, sleep intervals have a direct negative impact on increasing traffic delay. Therefore, energy efficiency in a TDM-PON presents a clear trade-off: the longer an ONU sleeps, the less energy it consumes, but the higher the delay experienced by the downlink traffic, and vice versa. In this paper, we propose an Adaptive Delay-Aware Energy Efficient (ADAEE) TDM-PON solution. The ADAEE aims at saving as much energy as possible while meeting the PON access delay restrictions imposed by the operator. We evaluate our solution in terms of energy consumption and delay performance using real traffic traces. The results demonstrate that the proposed solution can meet delay requirements while being more energy efficient solution compared to the existing solutions.  相似文献   

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