一个MPLS流量工程的QoS路由算法

传统Internet中,多媒体流量和实时电子商务应用会引起品质的降低。这可以通过在网络中动态地建立有带宽和延迟保证的路径来解决。讨论了基本算法,如最宽最短路径（WSP）,复杂一些的算法如最小冲突路由（MIRA）或基于剖面的路由。提出了一个新的MPLS网络中的Diff-Serv流的QoS路由算法。这个方法在维持网络效率的同时,有效地传输多媒体流量。     

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     

一种基于网络最大流的MPLS流量工程动态路由算法

在MPLS技术基础上提出了一种基于网络最大流的有带宽保证的动态路由算法-MBGRA,该算法通过链路对结点对之间的网络最大流的贡献程度以及链路的带宽利用率来定义链路权重,并且链路对将来建立新的标签交换路径的影响一同考虑.     

RATES: a server for MPLS traffic engineering

It has been suggested that one of the most significant reasons for multiprotocol label switching (MPLS) network deployment is network traffic engineering. The goal of traffic engineering is to make the best use of the network infrastructure, and this is facilitates by the explicit routing feature of MPLS, which allows many of the shortcomings associated with current IP routing schemes to be addressed. This article describes a software system called Routing and Traffic Engineering Server (RATES) developed for MPLS traffic engineering. It also describes some new routing ideas incorporated in RATES for MPLS explicit path selection. The RATES implementation consists of a policy and flow database, a browser-based interface for policy definition and entering resource provisioning requests, and a Common Open Policy Service protocol server-client implementation for communicating paths and resource information to edge routers. RATES also uses the OSPF topology database for dynamically obtaining link state information. RATES can set up bandwidth-guaranteed label-switched (LSPs) between specified ingress-egress pairs. The path selection for LSPs is on a new minimum-interference routing algorithm aimed at making the best use of network infrastructure in an online environment where LSP requests arrive one by one with no a priori information about future requests. Although developed for an MPLS application, the RATES implementation has many similarities in components to an intradomain differentiated services bandwidth broker     

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。     

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     

Generic multipath routing concept for dynamic traffic engineering

This letter presents a generic adaptive multipath routing solution. The method, called Core-State-Limited Load Sharing (CSLLS), has two parameters. One determines the adaptation time to load changes and the other one controls how long the path of a flow is unchanged. With these two parameters CSLLS is capable of modelling previous multipath routing concepts like ECMP, OMP and QoSPF. CSLLS overcomes the limitations of earlier approaches by being adaptive (opposed to ECMP), by ensuring path integrity for a flow (opposed to OMP), and by relying on only a few stored states in core routers (opposed to QoSPF).     

QoS online routing and MPLS multilevel protection: a survey

A survey of MPLS protection methods and their utilization in combination with online routing methods is presented in this article. Usually, fault management methods pre-establish backup paths to recover traffic after a failure. In addition, MPLS allows the creation of different backup types, and hence MPLS is a suitable method to support traffic-engineered networks. In this article, an introduction of several label switch path backup types and their pros and cons are pointed out. The creation of an LSP involves a routing phase, which should include QoS aspects. In a similar way, to achieve a reliable network the LSP backups must also be routed by a QoS routing method. When LSP creation requests arrive one by one (a dynamic network scenario), online routing methods are applied. The relationship between MPLS fault management and QoS online routing methods is unavoidable, in particular during the creation of LSP backups. Both aspects are discussed in this article. Several ideas on how these actual technologies could be applied together are presented and compared.     

TEAM: A traffic engineering automated manager for DiffServ-based MPLS networks

In this article an automated manager called traffic engineering automated manager (TEAM) for DiffServ/MPLS networks is introduced, and its design and implementation details are discussed. TEAM is designed for complete automated management of an Internet domain. TEAM is an adaptive manager that provides the required quality of service to the users and reduces the congestion in the network. The former is achieved by reserving bandwidth resources for the requests and the latter by distributing the load efficiently. These goals are achieved by online measurements of the network state. TEAM is composed of a traffic engineering tool (TET), which adaptively manages the bandwidth and routes in the network, a measurement and performance evaluation tool (MPET), which measures important parameters in the network and inputs them to the TET, and a simulation tool (ST), which may be used by TET to consolidate its decisions. These three tools work in synergy to achieve the desired network operation objectives. The experimental results demonstrate the efficiency of TEAM as a network manager in different and unpredictable traffic conditions at the expense of a limited increase in the computational complexity and costs.     

A distributed routing algorithm for datagram traffic in LEOsatellite networks

Satellite networks provide global coverage and support a wide range of services, low Earth orbit (LEO) satellites provide short round-trip delays and are becoming increasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. In this work, a datagram routing algorithm for LEO satellite networks is introduced. The algorithm generates minimum propagation delay paths. The performance of the algorithm is evaluated through simulations. The robustness issues of the algorithm are also discussed     

An overview of routing optimization for internet traffic engineering

Traffic engineering is an important mechanism for Internet network providers seeking to optimize network performance and traffic delivery. Routing optimization plays a key role in traffic engineering, finding efficient routes so as to achieve the desired network performance. In this survey we review Internet traffic engineering from the perspective of routing optimization. A taxonomy of routing algorithms in the literature is provided, dating from the advent of the TE concept in the late 1990s. We classify the algorithms into multiple dimensions: unicast/multicast, intra-/inter- domain, IP-/MPLS-based and offline/online TE schemes. In addition, we investigate some important traffic engineering issues, including robustness, TE interactions, and interoperability with overlay selfish routing. In addition to a review of existing solutions, we also point out some challenges in TE operation and important issues that are worthy of investigation in future research activities.     

MPLS流量工程及基于约束路由计算的研究

论述了 MPLS 网络的架构及其对流量工程的支持,研究了基于 MPLS 流量工程要解决的几个主要问题：如何把数据包映射为转发等价类等,并对其中最重要的一个——通过 LSP 把流量中继映射到实际网络拓扑,提出了一种约束最短路径优先算法的实现方法。     

Identifying online traffic based on property of TCP flow

Classification of network traffic using port-based or payload-based analysis is becoming increasingly difficult when many applications use dynamic port numbers, masquerading techniques, and encryption to avoid detection. In this article, an approach is presented for online traffic classification relying on the observation of the first n packets of a transmission control protocol (TCP) connection. Its key idea is to utilize the properties of the observed first ten packets of a TCP connection and Bayesian network method to build a classifier. This classifier can classify TCP flows dynamically as packets pass through it by deciding whether a TCP flow belongs to a given application. The experimental results show that the proposed approach performs well in online Internet traffic classification and that it is superior to naive Bayesian method.     

一种基于跳数和时延的MPLS自适应流量工程算法

提出了一种基于跳数和时延的MPLS自适应流量工程算法，该算法根据LSP的跳数和时延来进行流量分配，从而减少由传统路由算法而引起的网络拥塞，优化网络资源的利用。仿真结果表明，该算法简单易行，性能良好。     

流量工程中静态路由算法的研究

该文提出了一种应用于流量工程环境中的静态路由算法。考虑当前的网络资源情况,分优先级别在网络中计算并配置标记交换路径(Label Switched Path,LSP),当某一优先级有多条 LSP需要并行配置时,利用遗传算法搜索最优或较优的配置方案,使得网络的链路带宽使用率低于管理员定义的某个限定值,达到合理分布资源的目的。此外,提出了一种改进的 Dijkstra 算法计算 LSP的最短路径。     

Prediction-based routing as RWA in multilayer traffic engineering

Multilayer traffic engineering (MLTE) allows coping with ever-increasing and varying traffic demands in IP-over-Optical multilayer networks. It utilizes cross-layer TE (Traffic Engineering) techniques to provision optical lightpath capacity to the IP/MPLS (Internet Protocol/ Multi-Protocol Label Switching) logical topology on-demand. Such provisioning however causes optical connection arrival rates that pose strong performance requirements to Routing and Wavelength Assignment (RWA) strategies. Collecting up-to-date network information for the RWA with rapidly changing network states can be quite difficult. Exposing optical layer state information to the IP layer in the overlay model, or transforming this optical layer information in a workable representation in an integrated control plane is similarly problematic. Prediction-Based Routing (PBR) has been proposed as a RWA mechanism for optical transport networks; it bases routing not on possibly inaccurate or outdated network state, but instead on previous connections set-up. In this article, we propose to implement PBR as the RWA mechanism in the optical layer of a multilayer network, and use the predictive capabilities of PBR to expose dynamic optical network information into the multilayer traffic engineering algorithm with minimal control plane overhead. Some simulations show the benefits of using the PBR in the optical layer for MLTE purposes.     

New preemption policies for DiffServ-aware traffic engineering to minimize rerouting in MPLS networks

The preemption policy currently in use in MPLS-enabled commercial routers selects LSPs for preemption based only on their priority and holding time. This can lead to waste of resources and excessive number of rerouting decisions. In this paper, a new preemption policy is proposed and complemented with an adaptive scheme that aims to minimize rerouting. The new policy combines the three main preemption optimization criteria: number of LSPs to be preempted, priority of the LSPs, and preempted bandwidth. Weights can be configured to stress the desired criteria. The new policy is complemented by an adaptive scheme that selects lower priority LSPs that can afford to have their rate reduced. The selected LSPs will fairly reduce their rate in order to accommodate the new high-priority LSP setup request. Performance comparisons of a nonpreemptive approach, a policy currently in use by commercial routers, and our policies are also investigated.     

Multi-layer based multi-path routing algorithm for maximizing spectrum availability

Last 2 decades have witnessed the spectrum resources scarcity which is caused by wireless networks’ ubiquitous applications. To utilize the rare spectrum resources more efficiently, Cognitive Radio (CR) technology has been developed as a promising scheme. However, in CR networks, a novel NP-Hard disjoint multi-path routing problem has been encountered due to the Primary Users’ (PUs’) random movements. To settle this problem, we present a Spectrum History Matrix mechanism to define long-term spectrum sensing information on time-spectrum level such that spectrum availability and communication efficiency can be quantized in CR networks. To lessen the possibility for an active PU to interrupt all paths simultaneously, a sub-optimal Multi-layer based Multi-path Routing Algorithm (MMRA) is provided to determine how to route multiple paths which are not under the same PUs’ interference ranges. Through theoretical and simulation analyses, MMRA can not only settle the disjoint multi-path routing problem in polynomial time complexity, but also maximize communication efficiency.     

Novel multi-path routing scheme for UWB Ad hoc network

1 Introduction Ad hoc networks and ultra-wideband communications technology are a key factor in the evolution of wireless communications. In ad hoc networks, wireless hosts can communications with each other in the absence of a fixed infrastructure. These networks typically consist of equal nodes that communication over wireless links without central control .The followings can be used to describe the ad hoc network[1]: ? Dynamic network topology ? Limited resource ? Multi-hop communication …     

Multihour engineering and traffic routing optimization in hierarchical telephone networks

Classical hierarchical routing in telephone networks is extended to a wider class called out-of-chain routing in such a way that some useful properties of hierarchical routing are retained. This new routing pattern offers more potential paths than the fixed hierarchical one and can be introduced as a dynamic routing where the fixed alternate sequences change at some predetermined instants during the day. The effect of this new routing pattern on the network performances is examined. The main topic of this paper is to present heuristic methods used to optimise such routings in large networks. We show on artificial networks that the throughput of a given network can be significantly improved by suitable routing choices. We demonstrate that the integration of routing changes within a multihour dimensioning process is possible but the lack of realistic data does not permit at this time to quantify the value of routing optimization on real networks.