Service-driven traffic engineering for intradomain quality of service management

Quality of service delivery in IP networks is an important area for service providers, pointing to new business opportunities for premium quality traffic. While there has been relevant research on traffic engineering for QoS management, the problem has never been addressed through a holistic approach that brings together service management and traffic engineering. We present an integrated approach to intradomain QoS management that brings together two-level service management and traffic engineering approaches, coupled through the concept of the resource provisioning cycle. We present validation results for MPLS-based traffic engineering through both testbed experimentation and simulation; we also present validation results for monitoring through testbed experimentation. The article updates, enhances, and validates the top-level view of this integrated architecture presented in our earlier paper (see Trimintzios, P. et al., IEEE Commun. Mag., vol.39 no.5, 2001).     

基于SDN的IP网络流量工程问题研究

文章以SDN为基础,对IP网络流量工程进行分析和研究,探讨了IP网络流量工程的实现原理、技术及功能模块,对IP流量工程的实现流程进行了分析,经过验证可知,文章提出的基于SDN的IP网络流量工程准确性和有效性良好。     

NetScope: traffic engineering for IP networks

Managing large IP networks requires an understanding of the current traffic flows, routing policies, and network configuration. However, the state of the art for managing IP networks involves manual configuration of each IP router, and traffic engineering based on limited measurements. The networking industry is sorely lacking in software systems that a large Internet service provider can use to support traffic measurement and network modeling, the underpinnings of effective traffic engineering. This article describes the AT&T Labs NetScope, a unified set of software tools for managing the performance of IP backbone networks. The key idea behind NetScope is to generate global views of the network on the basis of configuration and usage data associated with the individual network elements. Having created an appropriate global view, we are able to infer and visualize the networkwide implications of local changes in traffic, configuration, and control. Using NetScope, a network provider can experiment with changes in network configuration in a simulated environment rather than the operational network. In addition, the tool provides a sound framework for additional modules for network optimization and performance debugging. We demonstrate the capabilities of the tool through an example traffic engineering exercise of locating a heavily loaded link, identifying which traffic demands flow on the link, and changing the configuration of intradomain routing to reduce the congestion     

XML-based configuration management for IP network devices

As the Internet continues to grow, the tasks of operations and management of IP networks and systems are becoming more difficult. Over the past few years, much effort has been given to improve the deficiencies of SNMP, but most have failed to be standardized. One critical deficiency of SNMP is in the area of configuration management. Recent work focuses on the use of XML technology for network and service management as an alternative or complementary approach to SNMP. This article presents the IETF's latest effort, Netconf, which is viewed by many as a promising revolutionary solution for configuration management. To validate this new effort, we present the design and implementation of an XML-based configuration management system based on Netconf. We also discuss our experience with XCMS and make some suggestions for improving the current Netconf protocol.     

IP骨干网流量的自动化预测

高效、可靠的网络流量预测是网络规划、扩容建设的基础。互联网流量目前缺乏完备的理论模型,行业内大多根据工程实践特点,设计简化可操作的预测模型以满足IP网络规划需求。首先根据中国电信自身IP骨干网流量预测工作的需求及特点,使用时间序列分析的多因子回归模型和函数自适应模型对IP骨干网流量进行分析和预测,基于大量现网实际数据的仿真运算,对比两种模型的特点、优劣和适用场景,提出了一种预测模型选择和参数优化的原则和方法。在此基础上,构建了可以满足百千量级时间序列要求的自动化流量预测系统,极大简化并提升了流量预测工作的效率。最后,展望了未来IP流量预测工作的延展方向和关注重点。     

Autonomic traffic engineering for network robustness

The continuously increasing complexity of communication networks and the increasing diversity and unpredictability of traffic demand has led to a consensus view that the automation of the management process is inevitable. Currently, network and service management techniques are mostly manual, requiring human intervention, and leading to slow response times, high costs, and customer dissatisfaction. In this paper we present AutoNet, a self-organizing management system for core networks where robustness to environmental changes, namely traffic shifts, topology changes, and community of interest is viewed as critical. A framework to design robust control strategies for autonomic networks is proposed. The requirements of the network are translated to graph-theoretic metrics and the management system attempts to automatically evolve to a stable and robust control point by optimizing these metrics. The management approach is inspired by ideas from evolutionary science where a metric, network criticality, measures the survival value or robustness of a particular network configuration. In our system, network criticality is a measure of the robustness of the network to environmental changes. The control system is designed to direct the evolution of the system state in the direction of increasing robustness. As an application of our framework, we propose a traffic engineering method in which different paths are ranked based on their robustness measure, and the best path is selected to route the flow. The choice of the path is in the direction of preserving the robustness of the network to the unforeseen changes in topology and traffic demands. Furthermore, we develop a method for capacity assignment to optimize the robustness of the network.     

MPLS and traffic engineering in IP networks

Rapid growth and increasing requirements for service quality, reliability, and efficiency have made traffic engineering an essential consideration in the design and operation of large public Internet backbone networks. Internet traffic engineering addresses the issue of performance optimization of operational networks. A paramount objective of Internet traffic engineering is to facilitate the transport of IP traffic through a given network in the most efficient, reliable, and expeditious manner possible. Historically, traffic engineering in the Internet has been hampered by the limited functional capabilities of conventional IP technologies. Recent developments in multiprotocol label switching (MPLS) and differentiated services have opened up new possibilities to address some of the limitations of the conventional technologies. This article discusses the applications of MPLS to traffic engineering in IP networks     

IP over WDM网络中一种新型虚拓扑构造算法

对IP over WDM的虚拓扑设计算法进行了研究，选择网络整体流量的均衡性作为优化目标，提出了一种新型的虚拓扑构造算法。在算法中，选择负载分布方差作为评价流量均衡性的指标，并给出其定义和计算方法。主要针对拥塞概率性能，在光层和IP层将提出的新型虚拓扑构造算法与其他算法进行比较。在光层的算法比较部分，选择负载均衡启发式路由算法（RLBH，routing with load balancing heuristics）与提出的算法进行比较；在IP层的算法比较部分，选择固定路径最小拥塞路由算法（FPLC，fixed-path least-congestion）与提出的算法进行比较，并对比较结果进行了讨论。比较结果显示在拥塞概率性能方面，提出的新型虚拓扑构造算法优于RLBH算法和FPLC算法。     

面向卫星网络的流量工程路由算法

针对卫星网络链路长时延、拓扑时变等特征,将链路传输时延引入并基于MPLS网络中源-目的节点对已知这一先验知识,提出了一种面向卫星网络的MPLS流量工程路由算法。该算法基于卫星网络时变拓扑模型的卫星拓扑快照,定义链路初始权重为链路剩余带宽、传输时延的综合函数,在为当前节点对建路时考虑其余节点对将来建路的可能需求计算链路的关键度,在此基础上通过链路权重的动态调整及延期选用实现流量工程,从而优化卫星网络的链路利用。实验表明,此算法在请求拒绝数、吞吐量、平均跳数及平均时延等方面性能都有较理想的提升。     

基于IP/MPLS网络的动态业务流量矩阵测量模型

IP网络动态业务流量矩阵的测量是业务量工程研究中的一个难点,本文提出了一种面向IP/MPLS骨干网络的基于LSP级的动态业务流量矩阵测量模型。该模型能够获取网络边界处对应于每一条LSP的路径转发信息,并根据每一条LSP上的测量结果,计算得知全网的业务流量矩阵。文中证明该测量模型是可行的,并给出了相关的算法及其性能分析。模型的优点是测量只在网络边界处进行而不涉及网络核心,故引起的网络开销较小。另外模型所需的算法复杂度低,仿真结果显示测量模型是有效的。     

大规模高速网络流量工程研究

主要讨论互联网主干上的流量工程。由于现在路由协议使网络的低效率和新的应用的出现，迫切要求发展新的技术、引进流量工程的观点来处理这些问题。介绍了MPLS等的新的IP交换技术及其相关的路由算法；讨论了在IP主干上电话传输技术。     

Stochastic traffic engineering for demand uncertainty and risk-aware network revenue management

We present a stochastic traffic engineering framework for optimizing bandwidth provisioning and route selection in networks. The objective is to maximize revenue from serving demands, which are uncertain and specified by probability distributions. We consider heterogenous demands with different unit revenues and uncertainties. Based on mean-risk analysis, the optimization model enables a carrier to maximize mean revenue and contain the risk that the revenue falls below an acceptable level. Our framework is intended for off-line traffic engineering design, which takes a centralized view of network topology, link capacity, and demand. We obtain conditions under which the optimization problem is an instance of convex programming and therefore efficiently solvable. We also study the properties of the solution and show that it asymptotically meets the stochastic efficiency criterion. We derive properties of the optimal solution for the special case of Gaussian distributions of demands. We focus on the impact of demand uncertainty on various aspects of traffic engineering, such as link utilization, bandwidth provisioning and total revenue. The carrier's tolerance to risk is shown to have a strong influence on traffic engineering and revenue management decisions. We develop the efficient frontier, which is the entire set of Pareto optimal pairs of mean revenue and revenue risk, to aid the carrier in selecting an appropriate operating point.     

On efficient traffic engineering with DV-based routing protocols in DiffServ-aware IP networks

In this paper, an approach to efficient traffic engineering in the DiffServ-aware network environment is proposed. We focus to distance vector-based routing protocols, considering both modifications of routing protocols needed to support path differentiation and traffic engineering methods relied on adjusting multiple per-link costs to particular network conditions. Further, a method for determining link cost of particular traffic class, as a unique generic function of the single generalized performance metric has been proposed. In order to achieve efficient traffic engineering, possible approximations of generic cost function and mappings of generalized to particular metrics have been proposed. Finally, prerequisites for implementing proposed approach have been discussed in the context of different administrative policies and time scales of their application.     

Scheduling and resources allocation in network traffic using multiobjective,multiuser joint traffic engineering

Wireless Networks - Reciprocal optimality is a desirable characteristic from the end user perspective, for both Best Effort and Quality of Service (QoS) datagrams delivery within a network. A...     

跨越不同容量设置DWDM网络的动态IP/DWDM综合路由算法研究

IP/DWDM网络的综合路由中的一个重要的研究问题就是如何对跨越不同DWDM网络的IP路由进行综合路由,特别是当两个DWDM网络的容量设置不同时。本文着重解决的就是如何对从单波长带宽大的网络进入单波长带宽小的网络传输的IP业务的综合路由问题。根据尽量鼓励对波长链路的带宽进行完全使用,以减小波长链路带宽碎片的原则,我们提出了两种解决算法:1 n 算法和 m n算法。仿真结果对两种算法的效率和性能进行了测试。     

MPLS advantages for traffic engineering

This article discusses the architectural aspects of MPLS which enable it to address IP traffic management. Specific MPLS architectural features discussed are separation of control and forwarding, the label stack, multiple control planes, and integrated IP and constraint-based routing. The article then discusses how these features address network scalability, simplify network service integration, offer integrated recovery, and simplify network management. Scalability is addressed through integrated routing enabling a natural assignment of traffic to the appropriate traffic engineering tunnels without requiring special mechanisms for loop prevention. Change is greatly reduced. The label stack enables an effective means for local tunnel repair providing fast restoration. Feedback through the routing system permits fast and intelligent reaction to topology changes. Service integration is simplified through a unified QoS paradigm which makes it simple for services to request QoS and have it mapped through to traffic engineering