软交换技术3

目前,软交换产品已经纷纷出台,基于软交换技术的下一代网络的试验也正在加紧进行,软交换的前景是广阔的。本期为本讲座的最后一期,将介绍软交换的标准化情况、可能的应用领域和一些厂家的软交换产品。前两期的主要内容为:软交换的体系结构、功能和对外接口,基于软交换技术的下一代网络的演进策略,以及基于软交换的开放业务提供。     

IaaS云中面向能源效率优化的虚拟机调度算法(英文)

In IaaS Cloud,different mapping relationships between virtual machines(VMs) and physical machines(PMs) cause different resource utilization,so how to place VMs on PMs to reduce energy consumption is becoming one of the major concerns for cloud providers.The existing VM scheduling schemes propose optimize PMs or network resources utilization,but few of them attempt to improve the energy efficiency of these two kinds of resources simultaneously.This paper proposes a VM scheduling scheme meeting multiple resource constraints,such as the physical server size(CPU,memory,storage,bandwidth,etc.) and network link capacity to reduce both the numbers of active PMs and network elements so as to finally reduce energy consumption.Since VM scheduling problem is abstracted as a combination of bin packing problem and quadratic assignment problem,which is also known as a classic combinatorial optimization and NP-hard problem.Accordingly,we design a twostage heuristic algorithm to solve the issue,and the simulations show that our solution outperforms the existing PM- or network-only optimization solutions.     

软件定义网络中可靠性优化控制器的位置研究(英)

By decoupling control plane and data plane,Software-Defined Networking(SDN) approach simplifies network management and speeds up network innovations.These benefits have led not only to prototypes,but also real SDN deployments.For wide-area SDN deployments,multiple controllers are often required,and the placement of these controllers becomes a particularly important task in the SDN context.This paper studies the problem of placing controllers in SDNs,so as to maximize the reliability of SDN control networks.We present a novel metric,called expected percentage of control path loss,to characterize the reliability of SDN control networks.We formulate the reliability-aware control placement problem,prove its NP-hardness,and examine several placement algorithms that can solve this problem.Through extensive simulations using real topologies,we show how the number of controllers and their placement influence the reliability of SDN control networks.Besides,we also found that,through strategic controller placement,the reliability of SDN control networks can be significantly improved without introducing unacceptable switch-to-controller latencies.     

一种基于高速弹性分组环的线性逼近公平算法

弹性分组环(RPR)中最关键的技术之一是环路分布式公平算法.IEEE802.17工作组制定的RPR草案中关于公平算法存在一些待完善的问题,比如在高速的网络中存在较长的收敛时间,同时对于非平衡流带来的永久性震荡现象也无法消除.本文针对上述这些问题提出了一种新的公平算法.仿真结果表明算法不仅能够消除非平衡流问题,而且能够公平地控制站点之间带宽的分配.     

一种新型提供服务质量保证的自适应无线局域网媒体接入协议

在无线局域网中提供QoS保证近年来日益成为研究热点.本文基于自适应无线局域网MAC协议在一种新的建模分析的基础上提出了一种提供QoS的新算法QoS-NSAD.QoS-NSAD赋予高优先级站点和低优先级站点不同的自适应特性从而很好地保证高负载环境高优先级用户的QoS特性.同时由于继承了以前算法的自适应机制,系统吞吐量能够逼近最优.大量仿真结果验证了算法的有效性.     

ATM与宽带信息网

介绍了ＡＴＭ与Ｂ－ＩＳＤＮ的关系，宽带信息网的组成，包括网络操作领域、用户领域、业务提供领域，以及发展宽带信息网的途径。     

ISDN和ISDN交换机

目前,世界上很多技术先进国家已经完成了ISDN(综合业务数字网)的现场试验,正准备在公用网中开放ISDN的试验业务,ISDN已逐渐由研究阶段转向实用阶段。ISDN的研究和开发使交换技术又向前迈进了一步,将传统的电话交换发展成综合业务的数字信息交换,这是继交换技术从模拟交换过渡到数字交换之后的又一次重大变革。本文主要介绍ISDN的基本概念和国际上研制ISDN的动向;ISDN对交换系统的要求以及将电话交换机改造成ISDN交换机的关键技术;此外本文还就将来宽带ISDN的交换技术略加讨论。     

面向对象方法在7号信令软件设计中的应用

随着交换技术的飞速发展，程控交换软件的规模越来越大，改动也越来越频繁，如何使代码对数据的改动具有相对的稳定性成为程控软件设计的一个首要问题。本文以ＣＣＳ７（７号公共信道信令）为例，从对象模型、动态模型、功能模型３个方面阐述了ＯＯ（面向对象）方法在ＣＣＳ７软件设计中的应用。这一方法，也可应用于程控软件的设计。     

智能网与宽带综合业务数字网1995年国际学术研讨会在京举行

智能网与宽带综合业务数字网１９９５年国际学术研讨会在京举行由北京邮电大学交换技术与通信网国家重点实验室和中国通信学会联合主办的“智能网与宽带综合业务数字网１９９５年国际学术研讨会”于４月１０日－１２日在北京召开。邮电部副部长林金泉出席会议并讲话。中国...