电力通信网络业务质量特征的数据流智能调度

在通信网络发生拥塞的情况下,为保证电力通信网络中业务稳定运行,针对目前电力通信网络QoS配置不完善等问题,本文设计并实现了一种基于电力通信网络业务质量特征的数据流调度策略。首先对电力通信业务进行优先级划分,并进行流分类。根据分好类别的电力通信业务流配置相应的流行为,并进行流分类到流行为的绑定,形成基于电力通信业务的流策略。实现在拥塞发生时,电力通信网络安全稳定运行。最后利用模拟网络进行实验,实验结果表明,配置QoS的网络其电力业务的丢包率和时延均控制在合适的范围,验证了基于电力业务的通信网络QoS配置策略的有效性,保证拥塞情况下电力通信业务稳定运行。     

基于流量特征的流调度策略研究综述

软件定义网络将网络的数据层和控制层相分离,具有可编程性强和全局网络视图的优点,这一优点被越来越多的应用于数据中心网络流调度中。然而,数据中心网络中大象流和老鼠流共存的流量特征是流调度技术的一大挑战。对基于流量特征的流调度策略进行了综述,首先梳理了基于软件定义网络的数据中心网络的理论基础,然后对大象流、老鼠流、大象流与老鼠流三个方面的流调度策略进行了分析和总结,并探讨了相比于传统的流调度技术,在软件定义网络架构下基于流量特征的流调度策略的优势。最后针对目前基于流量特征的流调度技术面临的若干主要问题进行了讨论,指出了下一步的研究方向。     

基于层次回声状态网络的电力EPON业务流感知

为了进一步提高电力EPON（Ethernet Passive Optical Network）对智能电网多业务的支持能力,文章提出了一种层次基于回声状态网络的电力EPON业务流感知技术,采用离散回声状态网络算法对电力通信业务流进行识别感知,以实现EPON对业务的高效匹配能力。在此基础上通过OLT与ONU的交互,优化电力EPON的资源调度与分配能力。为了验证所提出的业务流感知机制,以配用电通信EPON作为典型业务,对基于回声状态网络算法的业务感知进行仿真,仿真结果表明该机制能有效降低丢包率和缩短时延,提高了EPON系统对电力通信多业务的支持能力。     

一种广电运营商HFC网络业务接纳控制架构

在广电运营商的业务提供系统中,HFC网络业务请求的接纳控制是一项关键技术。首先分析了HFC网络业务请求接纳控制面临的问题,在此基础上提出了一种接纳控制的统一架构。该架构将针对业务请求的接纳控制策略分为接纳判定策略和频点选择策略,其中,接纳判定策略用于对业务请求是否允许接纳进行控制,频点选择策略用于对业务请求接纳到哪个频点进行控制。在该架构中这两种策略采用一个统一的流程进行调用。采用该架构可以支持已有业务请求接纳控制策略的灵活调整和新业务请求接纳控制策略的灵活扩展。     

基于SDN的数据中心动态优先级多路径调度算法

随着云计算技术和分布式业务的发展,数据中心内部“东西向”大象流量激增,这部分大象流在调度不当的情况下容易发生碰撞,造成链路拥塞。本文提出一种基于软件定义网络（SDN）的动态优先级多路径调度算法（DPMS）。该算法根据数据中心流量的特点制定大象流和老鼠流调度模型,充分利用各网络节点间的冗余链路,提高资源利用率;并结合组表优化SDN架构中控制器和交换机的通信模式,降低了数据包处理时延。实验结果表明,相比ECMP和Hedera这2种调度策略,DPMS提高了网络吞吐量和链路利用率,减少了平均流完成时间,网络的整体性能有所提高。     

基于SDN-NFV的移动核心网联动机制研究

针对当前移动核心网中业务复杂僵化的问题,提出一种基于网络功能虚拟化及软件定义网络的联动机制,通过整合控制面信息,完成复杂业务的部署以及业务链与匹配策略的动态更新,实现从逻辑规则到转发流表的物理映射,保障基于业务链的通信模式,满足服务质量的需求。实验结果表明,该联动机制可以实现高效快速的业务链部署,有效满足移动网络对灵活性及可扩展性的要求。     

基于SDN的物联网业务流路由策略模型

随着物联网技术广泛地应用在各个领域，物联网中业务种类及其流量也愈发丰富，业务流量的增加为物联网的管理和质量保证带来了巨大的挑战。针对物联网中流量大，特征属性多，业务繁杂等特点，提出了基于决策树的业务流分类模型，通过SDN控制平面将物联网中的业务流进行分类，然后根据不同业务流量对网络需求的不同设计了基于网络状态QoS的业务流调度策略，通过该策略为业务流量选择最优的传输路径，从而保障物联网中不同业务的数据服务质量，提高物联网的数据传输效率。     

无线网络节点功率控制仿真研究

在WNCS(无线网络控制系统)仿真中节点的功率控制是仿真关键问题之一。为了研究节点的功率控制问题,基于Truetime工具箱中的Kernel模块和Wireless Network模块,首先,提出了两种功率控制策略,一种是把网络控制中RM(RateMonotonic)调度策略的思想应用到节点功率的控制和调度中,而提出的PM(Power Monotonic)功率控制策略,另一种是基于TrueTime仿真示例通过归纳而提出的AH功率控制策略,并着重介绍了PM功率控制策略的算法。最后通过一个无线网络控制系统的仿真模型,就这两种节点功率控制策略对系统性能的影响进行仿真验证。     

基于结构化对等网络的高效分布式任务调度

提出与描述了一个基于结构化对等网络的高效分布式任务调度策略HDTS(High-Efficient Distributed Task Scheduling)。HDTS建立在结构化对等网络的应用层覆盖网络上,保证了系统的非集中性、可扩展性、自组织性,以及规模大的优点。HDTS把基于Chord风格的对等网络协议和容错及高效的多播调度策略结合起来,允许分布式计算的各种大量的子任务在对等网络的节点上高效的调度、分配、执行。除了支持主-从风格的并行计算外,系统允许具有数据依赖的分布式旅行商算法正确的执行,使系统具有通用性和开放性。测试结果表明:HDTS具有正确性与高效性,可以作为对等网络上计算资源高效共享与聚集的可行方案。     

ATM流量控制方法的比较

ＡＴＭ网络能以不同的ＱｏＳ（服务质量）支持多种业务类型有赖于有效的流量控制策略。对于象ＣＢＲ（恒定比特业务）和ＶＢＲ（可变比特业务）这样的实时通讯业务采用开环控制是合理的,而对于主要应用于数据通信的ＡＢＲ业务则采用闭环控制以更有效的利用网络带宽资源。本文阐述了基于信誉和基于速率的闭环流控策略,分析了ＡＴＭ论坛最终支持速率方案的原因,同时也讨论了几种集成信誉流控和速率流控的方案。     

Scalable services via egress admission control

Allocating resources for multimedia traffic flows with real-time performance requirements is an important challenge for future packet networks. However, in large-scale networks, individually managing each traffic flow on each of its traversed routers has fundamental scalability limitations, in both the control plane's requirements for signaling, state management, and admission control, and the data plane's requirements for per-flow scheduling mechanisms. In this paper, we develop a scalable architecture and algorithm for quality-of-service management termed egress admission control. In our approach, resource management and admission control are performed only at egress routers, without any coordination among backbone nodes or per-flow management. Our key technique is to develop a framework for admission control under a general “black box” model, which allows for cross traffic that cannot be directly measured, and scheduling policies that may be ill-described across many network nodes. By monitoring and controlling egress routers' class-based arrival and service envelopes, we show how network services can be provisioned via scalable control at the network edge. We illustrate the performance of our approach with a set of simulation experiments using highly bursty traffic flows and find that despite our use of distributed admission control, our approach is able to accurately control the system's admissible region under a wide range of conditions     

一种提供延迟保证的多级FIFS队列包调度算法

包调度算法是提供服务质量保证的一个重要部分.传统的每流区分的包调度方法通常不能支持较好的扩展性,不适应当前网络带宽的迅速增长.而非每流区分的方法又不能提供每流的服务保证.动态包状态(dynamic packet state,简称DPS)方法提供了一种在无须维护每流状态下提供保证服务的方法,该方法在保证服务质量的同时大大提高了扩展性.但是它仍然需要每包的调度,其复杂度和包的数量有关.在DPS的基础上提出了一种用多级FIFS队列提供延迟保证的包调度算法,并给出了该算法实现服务保证的约束条件.理论分析和仿真实验结果都表明:该算法可以实现常数时间的包调度复杂性,同时具有和DPS同样的延迟性能.     

Tight end-to-end per-flow delay bounds in FIFO multiplexing sink-tree networks

Aggregate scheduling has been proposed as a solution for achieving scalability in large-size networks. However, in order to enable the provisioning of real-time services, such as video delivery or voice conversations, in aggregate scheduling networks, end-to-end delay bounds for single flows are required. In this paper, we derive per-flow end-to-end delay bounds in aggregate scheduling networks in which per-egress (or sink-tree) aggregation is in place, and flows traffic is aggregated according to a FIFO policy. The derivation process is based on Network Calculus, which is suitably extended to this purpose. We show that the bound is tight by deriving the scenario in which it is attained. A tight delay bound can be employed for a variety of purposes: for example, devising optimal aggregation criteria and rate provisioning policies based on pre-specified flow delay bounds.     

虚拟时钟调度算法研究

FIFO队列调度算法由于实现简单、执行效率高而在网络中得到大量的应用，但FIFO队列无法实现对资源的分配；男种调度算法公平队列调度则可以实现对带宽资源的公平分配，但是它存在可扩展性问题。而基于虚拟时钟的算法在实现对资源进行公平分配的同时具备良好的可扩展性，从而能够满足QoS控制中对于分组调度算法的需求。本文主要对一些基于虚拟时钟的度算法进行了分析和讨论，这也是进行QoS控制研究的基础。     

A fair scheduling discipline for Ethernet passive optical networks

We propose a novel policy for scheduling upstream flows in Ethernet passive optical networks. This policy, called proportional sharing with load reservation (PSLR), provides bandwidth guarantees on a per-flow basis and redistributes the unused bandwidth among active flows in proportion to their priority level. We establish convergence conditions for the PSLR policy and show that it provides a fair service distribution among the flows. Moreover, we establish bounds for the backlog and delay on a per-flow basis, thus enabling a network to provide its users with absolute performance guarantees.     

一种适用突发流量的数据中心网络流调度策略

云数据中心网络的流调度问题是当下的一个研究热点.比较具有实用性的流调度是不假设流信息预先可知,但目前这类流调度方案在流量突发时的表现并不理想.提出了一种针对流量突发情况的流调度方案,通过将每流排队与多级反馈队列调度相结合,实现了一个基于流隔离的多级调度方案FISH,解决了流量突发情况下不同流的排队竞争问题.实验结果表明,该方案性能稳定,可以将小流完成时间降低8.6%以上.     

Adaptive network-traffic balancing on multi-core software networking devices

Software networking devices running on commercial-off-the-shelf hardware offer more flexibility and less performance than high-end, dedicated, networking devices. However, this lack of performance can be compensated, to some extent, by multi-core processors that can manage network packets in parallel. In order to efficiently utilize multi-core architectures, the processing load and the network traffic must be properly balanced to optimize the inter-core communication. Here, we analyze the traffic distribution on a per-packet and per-flow basis and verify the performance of the Linux Bridge networking device. A new, adaptive, traffic-distribution method is proposed, which combines packet-based and flow-based traffic distributions. The method was experimentally validated by two test cases – the “worst-case” scenario, with one dominant flow, and the “backbone-link” scenario, with a large number of flows that have a similar packet rate. In the case of one dominant flow, the performance in traffic throughput is improved by a factor of 2.8 by engaging four processing cores. In the case of a large number of traffic flows, the performance remains similar to the existing flow-based methods.     

动态决策域多业务接纳控制研究

基于无信令判决的流感知接纳控制实现了多业务接入区分,为不同业务提供了差异化性能保障.由不同业务状态指标构建的链路状态空间能够对业务流间的相互影响进行响应,实时调整进程中不同业务流的分布.在模糊化状态指标门限的基础上,映射状态空间的动态决策域,并构建对应判决表,节点仅由业务感知类型和判决表执行业务区分的接纳控制,保障已接纳业务请求的服务质量.推导出链路状态转移的稳定性条件是弹性流不过载,仿真证明了链路公平速率的稳定性.     

A calculus for stochastic QoS analysis

The issue of Quality of Service (QoS) performance analysis in packet-switched networks has drawn a lot of attention in the networking community. There is a lot of work including an elegant theory under the name of network calculus, which focuses on analysis of deterministic worst case QoS performance bounds. In the meantime, researchers have studied stochastic QoS performance for specific schedulers. However, most previous works on deterministic QoS analysis or stochastic QoS analysis have only considered a server that provides deterministic service, i.e. deterministically bounded rate service. Few have considered the behavior of a stochastic server that provides input flows with variable rate service, for example wireless links. In this paper, we propose a stochastic network calculus to analyze the end-to-end stochastic QoS performance of a system with stochastically bounded input traffic over a series of deterministic and stochastic servers. We also prove that a server serving an aggregate of flows can be regarded as a stochastic server for individual flows within the aggregate. Based on this, the proposed framework is further applied to analyze per-flow stochastic QoS performance under aggregate scheduling.     

Conformance analysis in networks with service level agreements

To achieve some level of Quality of Service (QoS) assurance, a network usually has Service Level Agreements (SLAs) with its users and neighboring domains, which describe the QoS level that the service provider is committed to provide, and the specification of traffic that users or neighboring domains are allowed to send. An interesting and important question arises as to whether a flow is still conformant to its original traffic specification after crossing the network since it may interact with other flows within the network. In this paper, we study analytically the extent to which a flow and an aggregate of flows become non-conformant through an analysis of the stochastic burstiness increase of flows after crossing a per-flow scheduling network and an aggregate scheduling network . The stochastic behavior of a server in aggregate scheduling networks is also studied to determine the conformance deterioration of individual flows, which provides the theoretical conformance deterioration bound and provides useful results for conformance analysis in an aggregate scheduling network with general topology. Our theoretical results are verified by extensive simulations.