Efficient hierarchical QoS routing in ATM networks

For reducing network information to achieve scalability in large ATM networks, ATM Private Network-to-Network Interface (PNNI) adopts hierarchical routing. Consequently, although routing complexity is significantly reduced, numerous issues in PNNI routing require further study to achieve more efficient, accurate, scalable, and QoS-aware routing.Several methods are adopted herein to achieve efficient, scalable, and QoS-aware ATM PNNI routing. First, an efficient aggregation scheme, referred to as Asymmetric Simple, is proposed. The aggregated routing information includes available bandwidth, delay and cost. Second, two approaches for defining link costs are investigated, namely, the Markov Decision Process (MDP) approach and the Competitive On-Line (COL) routing approach, and these are compared with the Widest Path (WP) approach. Finally, a dynamic update policy, referred to as the dynamic cost-based update (DCU) policy, is proposed to improve the accuracy of the aggregated information and the performance of hierarchical routing, while decreasing the frequency of re-aggregation and information distribution.Simulation results demonstrate that the proposed Asymmetric Simple aggregation scheme yields very good network utilization while significantly reducing the amount of advertised information. Between these two link cost functions, the MDP approach provides a systematic method of defining call admission function and yields better network utilization than the COL approach. The proposed DCU policy also yields an enhanced network utilization while significantly reducing the frequency of re-aggregation and the amount of distributed aggregation information.     

异种ATM网络互连标准PNNI

详细介绍了异种ＡＴＭ网络互连标准ＰＮＮＩ，ＰＮＮＩ较好地解决了人们普遍关心的多厂家ＡＴＭ产品互连网络交换虚电路的建立问题。     

Modeling and analyzing the performance of adaptive hierarchical networks

As networks become larger, scalability and QoS-awareness become important issues that have to be resolved. A large network can be effectively formed as a hierarchical structure, such as the inter/intra-domain routing hierarchy in the Internet and the Private Network-to-Network Interface (PNNI) standard, to resolve these critical issues. Methods of modeling and analyzing the performance of QoS-capable hierarchical networks become an open issue. Although the reduced load approximation technique has been extensively applied to flat networks, the feasibility of applying it to the hierarchical network model has seldom been investigated. Furthermore, most of the research in this area has focused on the performance evaluation with fixed routing. This work proposes an analytical model for evaluating the performance of adaptive hierarchical networks with multiple classes of traffic. We first study the reduced load approximation model for multirate loss networks, and then propose a novel performance evaluation model for networks with hierarchical routing. This model is based on a decomposition of a hierarchical route into several analytic hierarchical segments; therefore the blocking probability of the hierarchical path can be determined from the blocking probabilities of these segments. Numerical results demonstrate that the proposed model for adaptive hierarchical routing yields accurate blocking probabilities. We also investigate the convergence of the analysis model in both the originating-destination (O-D) pair and the alternative hierarchical path. Finally, the blocking probability of the adaptive hierarchical O-D pair is demonstrated to depend on the blocking of all hierarchical paths but not on the order of the hierarchical path of the same O-D pair.     

Fast setup of end-to-end paths for bandwidth constrained applications in an IP/MPLS–ATM integrated environment

Transport networks are currently being moved towards a model of high performance Internet Protocol/Multiprotocol Label Switching (IP/MPLS) routers interconnected through intelligent core networks. Currently, Asynchronous Transfer Mode (ATM) technology has been widely deployed in several network backbones along with the Private Network-to-Network Interface (PNNI) protocols as the control plane. In order to cope with the increasing Internet traffic demands in the current context, fast setup of end-to-end paths with the required Quality of Service (QoS) is necessary.This paper analyzes the case of two IP/MPLS networks interconnected through an ATM core network, assuming MPLS as the mechanism to provide Traffic Engineering in the IP networks, and a PNNI-based control plane in the core network. This paper aims to define a mechanism needed to set up a fast end-to-end QoS Label Switched Path (LSP) between two Label Switched Routers (LSRs) belonging to different IP/MPLS domains. First, the fast end-to-end setup is achieved by modifying the network backbone control plane. Second, two different aggregation schemes are proposed to summarize the QoS network state information to be transported through the ATM core network. Therefore, both the efficient aggregation schemes and the fast mechanism allow source routing to set up a path faster than the existing methods and to reduce the blocking probability using a summary of the available resource information.     

支持时延-带宽约束的动态层次组播路由

层次网络及层次路由成为解决大规模网络QoS路由可扩展性问题的一个主要手段.文中对PNNI层次网络模型下的时延-带宽多QoS约束的动态组播路由问题进行了全面研究:在已提出支持时延-带宽约束的拓扑聚集算法(Stair)的基础上,进一步对组播树节点需维护的组播树状态信息及其聚集问题进行研究,并提出"伪树上边界节点"模式的域内组播树状态信息的聚集方法,最后设计了基于聚集拓扑信息和组播树状态信息的动态层次组播路由算法.仿真结果显示,该路由不仅大量压缩了存储和扩散的拓扑信息和组播树状态信息,同时还保持了与平面网络近似的路由效率,实现了大规模网络情况下组播路由的扩展.     

基于智能算法的层次型多链WSN路由协议

路由协议设计是无线传感器网络的一个重要领域,可靠性、低开销、易于维护是无线传感器网络路由协议的设计目标。本文基于层次型拓扑控制思想,并在成链算法PEGASIS基础上引入智能成链策略,提出新的路由协议——HMCRP（Hierarchical Multi-Chain Routing Protocol）。HMCRP基于虚拟网格方式将网络划分为两层自治区域,简化拓扑复杂度;区域内节点按照蚁群算法成链,保证形成全局最优或较优的传输路径;提出链头选取公式,综合考虑节点性能、区域链的数据传输代价。通过matlab与omnet++相结合的仿真实验,与PEGASIS协议及其改进协议相比较,验证了HMCRP在延长网络生命周期、降低数据传输平均能耗以及提高数据接收率等方面的优势。     

ATM网间互连拓扑聚集的分析

该文就异种ＡＴＭ网间的互连作了一些探讨。认为拓扑聚集的难度及ＡＴＭ 　Ｆｏｒｕｍ　ＰＮＮＩ路由标准的不足等是ＡＴＭ网互连的主要障碍。     

基于SDN分级分域架构的QoS约束路由算法

传统分布式的网络架构制约路由算法的创新,软件定义网络的出现为路由算法的优化提供了新思路。已有研究中,启发式算法广泛应用于服务质量路由,但由于计算复杂度高而无法在大型网络中应用。而其他算法均存在不同程度的问题,要么复杂度较高,要么算法性能较差,如最短路径算法。基于 SDN 分级分域架构,提出了 LC-LD 路由算法,综合时延条件和代价度量约束并在计算复杂度和算法性能之间保持平衡。仿真分析表明,LC-LD路由算法在有较低的计算复杂度的同时还有较高的服务质量路由选路性能。     

Congestion control based dynamic routing in ATM networks

In this paper we describe briefly a dynamic multi-path algorithm that has been considered for connection oriented asynchronous transfer mode (ATM) networks. Our scheme takes advantage of a cell multiplexing capability that has particular advantage in networks supporting variable bit rate (VBR) traffic. The fundamental objective of the scheme is to propose a congestion control based scheme that bridges the gap between routing and congestion control as the network becomes congested. The proposed routing scheme works as a shortest path first algorithm under light traffic conditions. However, as the shortest path becomes congested under unbalanced heavy traffic, the source uses multiple paths when and if available to distribute the calls and reduce cell loss. This mechanism will provide good Quality of Service for clients within the given constraints. We compare the performance of the proposed scheme with other competitive schemes. The throughput and cell loss performance are compared via simulations. These have been carried out concentrating on a five node network, each with varying traffic patterns, with the intention of gaining insight into the strengths and weaknesses of the various schemes.     

点对点网络容错路由算法的概率分析

基于网络中结点错误概率 ,提出一种新的概率分析方法 ,对网络中点对点的路由算法的容错性概率、路径长度、算法复杂性进行严格的推导 .以超立方体网络为分析的网络拓扑 ,提出在其上的一个路由算法 .分析表明 :在所有实际规模的超立方体网络中 (其结点数可以高达十亿个 ) ,在相当大的结点出错概率 (可高达 8% )的情况下 ,路由算法可达到 99.9%的成功概率     

关于ATM技术中的障碍与未决之问题

本文主要探讨了当前ATM技术发展中存在的一些亟待解决的问题,包括信令标准的混乱、服务质量约定支持的缺乏、拥塞控制算法的不统一、与传统网络互联的困难、PNNI路由算法的有效性和防火墙功能等六个方面。     

基于VP的ATM网中多项服务质量路由算法

ＡＴＭ网传统的路由方案所考虑的仅是可连接性,对于基于ＶＰ的ＡＴＭ网,提出了一种以代价和时延多服务品质,基于Ｄｉｊｋｓｔｒａ算法的路由算法,算法简单易行,计算复杂度低。     

A new algorithm for virtual path network design in ATM networks

Virtual paths (VPs) in an ATM network form a logical network, called VP network (VPN), over the underlying physical network. VPN allows flexible management of network resources and hence its design is an important issue in designing an ATM network. In this paper, we consider the VPN design problem which is formulated as an optimization problem with the objective of minimizing the switching and transmission cost, and control and management cost. We present here, a two-phase heuristic solution for designing a good VPN for a given traffic demand. The first phase is a routing phase in which a route is found between every node pair in the network. In the second phase, paths are selected as VPs using the set of routes generated in the routing phase. A path is selected as a VP so as to minimize the following parameters: (i) the total number of VPs configured; (ii) the number of VPs carried by a link (load); and (iii) the VP hopcount, the number of VPs that are concatenated to form a virtual channel (VC). We study the performance of the proposed algorithm through extensive simulation on various networks. The results show that the VPN generated by the proposed algorithm is good in minimizing the number of VPs configured, the load on a link, and the VP hopcount. The comparison of the results obtained by the proposed algorithm and that of Ahn et al. [Virtual path layout design in ATM networks, in: Proceedings of IEEE INFCOM’94, Toronto, Ontario, Canada, 1994, pp. 192–200] shows that our algorithm performs better.     

Multi-robot navigation based QoS routing in self-organizing networks

The technical development drives the future networks to become large-scale, heterogeneous, and dynamic. Bio-inspired networking can help reduce the time-space complexity of the complex network. Due to the good features such as self-organization and self-management, self-organizing network (SON) will most probably be a priority choice for the next generation network. In this paper, a swarm intelligence based Quality of Service (QoS) routing protocol is proposed for SON. The inaccurate routing and QoS information is described with fuzzy mathematics whilst the utilities of both the user and the network service provider are considered by applying game theory. Based on the multi-robot navigation algorithm, the protocol is able to search a routing path which can satisfy the user QoS requirements and achieve the Pareto optimal utilities of the user and the network service provider under Nash equilibrium. The proposed protocol is implemented and evaluated by extensive simulation experiments. The results show that it beats both other swarm intelligence based routing protocols and the traditional Dijkstra algorithm based routing protocol. The searched routing paths support the win–win effect for both the user and the network service provider.     

基于混合量子进化算法的高效节能无线传感器网络路由算法

在无线传感器网络中,层次型路由算法能减少节点能量消耗和延长网络生存周期.因此在LEACH算法和PEGASIS算法的基础上,提出了一种基于混合量子进化算法的高效节能的无线传感器网络路由算法HERA.该算法中把网络分为多个簇,每个簇中的节点连接成为一条多跳通讯链路,并使用混合量子进化算法来得到最优的分簇组链方式,以减少链路...     

Efficient algorithms to solve the link-orientation problem for multi-square, convex-bipartite, and convex-split networks

This paper studies the issue of assigning orientations to all links of an undirected network, which is called the link-orientation problem (LOP). First, we describe some practical variations and address some complexity analysis in LOPs for general networks. Then, we design efficient algorithms to solve these LOPs issues. The proposed approach employs the recursive shortest path rules and the efficient cost cores scheme to resolve the LOP issues for some weighted network systems. These classes of networks include multi-square, convex-bipartite, and convex-split networks. Next, we use the cost core algorithm for adjusting LOP and obtain the more efficient LOP for the weighted convex-bipartite and convex-split networks. In general, the LOP scheme can support the actual applications requirements to realize a WFQ (weighted fair queuing) task for multicast routing in real networks. Finally, the findings of this paper can be mainly applied to some network applications, including efficient revision of load balancing in a ATM switch network, quick selection of a firm’s PCS (Proxy Cache Server) on the Web, and dynamic adjusting of link’s changing conditions in a workflow system on the Internet.     

An improved scheme for self-healing in ATM networks

Broadband networks based on ATM technology can carry a large volume of data and can support diverse services like audio, video, and data uniformly. The reliability and availability levels provided by such networks should be very high. Self-healing is an elegant concept in this direction to provide highly reliable networks. A self-healing network can detect failures such as link/node failures and reroute the failed connections automatically using distributed control mechanisms. In this paper, we consider link and node failures including the VP terminating nodes unlike Kawamura and Tokizawa (Self-healing in ATM networks based on virtual path concept, IEEE Journal on Selected Areas in Communications 12 (1) (1994) 120–127). We present here an improved scheme for self-healing in ATM networks based on the concept of backup VPs. The problems we address are: (i) self-healing scheme; and (ii) backup VP routing. Two issues are addressed in the self-healing scheme: (i) backup VP activation protocol; and (ii) dynamic backup VP routing. We propose a new backup VP activation protocol which uses a VC packing strategy which allows the fast and prioritized restoration of critical VCs that were carried by failed VPs. We also propose a distributed dynamic backup VP routing algorithm which reduces the resource contention that may occur when multiple source–destination pairs contend for the routes simultaneously. The objective of the backup VP routing problem is to find a backup VP for each of the working VPs so that the cost of providing the backup is minimized. We propose a heuristic based solution for the backup VP routing problem using the concept of minimum cost shortest paths. We conducted simulation experiments to evaluate the performance of the proposed schemes. The results show that the proposed schemes are effective. Comparison of the results with those of the earlier schemes (R. Kawamura, I. Tokizawa, Self-healing in ATM networks based on virtual path concept, IEEE Journal on Selected Areas in Communications 12 (1) (1994) 120–127; C.J. Hou, Design of a fast restoration mechanism for virtual path-based ATM networks, Proceedings of IEEE INFOCOM’97, Kobe, Japan, April 1997) shows that the proposed schemes perform better.     

基三分层互连网络及其路由算法设计

从降低节点度、减少网络链路数和缩短网络直径的角度出发,提出一种新型的互连网络结构--基三分层互连网络,深入地研究了该网络的静态度量并和2-D Mesh做了相应的比较.针对基三分层互连网络提出了一种使消息沿两节点间确定路径传递的分布式确定路由算法DDRA.该算法充分利用基三分层互连网络的层次特性,不需要构建路由表,且算法实现简单,路由效率高,且易于硬件实现.     

LEO卫星网络中的一种分布式路由算法

在LEO卫星网络中,由于卫星高速运动导致的网络拓扑变化和不同卫星覆盖城内流量的非规整性给设计其特殊路由算法带来很大挑战。结合卫星网络的固有特点,本文提出一种基于路径信息压缩的分布式路由算法CPDR（Compressed Path Information based Distributed Routing）。该算法使用分布式分层链路状态收集策略和简洁的路径信息编码机制,能够在不引入额外信令开销基础之上提供多路径路由能力,实现卫星网路中的流量负载平衡、优化网络带宽应用、提高星际链路利用率。     

Analyzing the performance of deferred reservations

This paper studies the performance of deferred resource reservation in data networks. Conventional resource reservation protocols, such as PNNI and RSVP adopt an all-or-nothing approach, where partially acquired resources must be released if resources are not available at all links on the chosen path. During periods of high network load, this leads users to retry requests repeatedly, adding control traffic at exactly the time when the network’s capacity to process that control traffic is exhausted. Deferred REServation (DRES) can significantly improve performance by reducing the overall call rejection probability, allowing more traffic to be carried, using the same resources. Call admissibility is increased by deferring requests at routers for a limited period of time until resources become available. The paper includes analytical models that predict the blocking probability on a DRES multiplexor and on a multi-hop path, and simulation results for substantial network configurations, using several QoS routing methods. The results show that DRES can provide substantial performance gains over traditional reservations (upto 50% with QoS routing enabled and upto an order of magnitude for non-QoS traditional routing).