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.     

RPR—新一代城域网传送技术

为了提供高质量的语音服务和满足迅速发展的数据服务，目前运营商正在建设或者完善自己的城域网络。针对城域网光纤环网设计的RPR技术可以有效地分配带宽，并且能够灵活、快速地配置网络，RPR网络将成为新一代城域网的重要组成部分。     

弹性分组环中几种公平算法研究

弹性分组环（RPR，Resilient Packet Ring）IEEES02．17技术是一种新的环网MAC层技术。它旨在提供环网的高吞吐量、高纠错率和空间复用能力。环网中的公平性已经被特别的关注，同样它也是弹性分组环的一个挑战。现分析了目前弹性分组环中的一些公平算法，指出了目前算法所存在的一些问题，并讨论了有待于进一步研究的课题。     

The IEEE 802.17 media access protocol for high-speed metropolitan-area resilient packet rings

The resilient packet ring (RPR) IEEE 802.17 standards is under development as a new high-speed technology for metropolitan backbone networks. A key performance objective of PRP is to simultaneously achieve high utilization, spatial reuse, and fairness, an objective not achieved by current technologies such as SONET and Gigabit Ethernet or legacy ring technologies, such as FDDI. The core technical challenge for RPR is the design of a fairness algorithm that dynamically throttles traffic to achieve these properties. The difficulty is in the distributed nature of the problem, that upstream ring nodes must inject traffic at a rate according to congestion and fairness criteria downstream. This article provides an overview of the RPR protocol with a focus on medium access and fairness.     

RPR的网络保护及其与SDH保护方式的互通

RPR是由顺时针、逆时针两个传输方向光环组成的,这种组网方式赋予RPR的健壮性。RPR的保护倒换机制主要有两种:采用定向保护机制和采用回绕保护机制。首先概述了RPR网络保护协议,然后分析了RPR的保护倒换机制及RPR的网络保护与SDH保护方式的互通。     

基于弹性分组环的城域网解决方案

文章介绍了弹性分组环的技术特点及其在网络中的应用,从实现的角度探讨了目前弹性分组环在城域网中的3种主流解决方案,包括采用RPR嵌入路由交换平台方式、采用纯RPR设备方式、采用RPR嵌入MSTP方式,解决方案涉及系统架构、网络应用环境、业务提供等方面.进而,文章在对3种解决方案进行对比的基础上,探讨了基于弹性分组环的城域网的发展趋势.     

SDH以太共享环在城域网的应用

随着因特网和数据业务的爆炸性增长，城域网的主要业务正在从话音向数据转移。然而过去的城域传送网是为话音业务设计的，所以采用的是TDMM网络(SDH、SONET)。本首先介绍了基于SDH网络传送数据业务的几种新技术，如：POS、GFP、LCAS、RPR、共享以太环等，以及可以实现业务隔离、保证安全的VLAN、VLAN嵌套技术，然后对各种城域网数据传输技术进行了比较，最后分新了薪一代的MSTP设各府该具有的几个特点。     

Analysis of fair rate calculations in resilient packet ring aggressive mode

Resilient packet ring (RPR) standardized as IEEE 802.17 is a new medium access control (MAC) protocol for metro-ring networks. RPR supports spatial reuse which increases the achieved throughput but it can also result in congestion and starvation of nodes on the ring. Therefore, it is necessary to employ mechanisms to enforce a fair allocation of the ring bandwidth in RPR. In order to maintain fairness among nodes, a fairness algorithm is deployed at each RPR node. When a node detects congestion, it calculates a fair rate which is advertised to all upstream nodes contributing to congestion. Upon receiving the fair rate, the upstream nodes limit the rate of their injected traffic to the advertised fair rate. Consequently, the congested node can utilize the unused capacity and add its local traffic to the ring. In this paper, we develop an analytical model for fair rate calculation in the RPR aggressive mode fairness algorithm in the parking-lot scenario. This model provides an insight on dynamics of the RPR fairness algorithm and can be used to evaluate its performance. We investigate this problem in two cases. First, we assume that the link propagation delay is zero and derive the fair rate equations for this ideal case. We then consider the link propagation delay and develop a more realistic model. We verify the accuracy of our model by simulation results. Furthermore, we use the developed model to study the impact of various parameters on convergence of the fair rate.     

Traffic grooming in WDM ring networks to minimize the maximum electronic port cost

We consider the problem of traffic grooming in WDM ring networks. Traffic grooming is a variant of the well-known logical topology design problem, and is concerned with the development of techniques for combining low speed traffic components onto high speed channels in order to minimize network cost. Previous studies have focused on aggregate representations of the network cost. In this work, we consider a Min-Max objective, in which it is desirable to minimize the cost at the node where this cost is maximum. Such an objective is of high practical value when dimensioning a network for unknown future traffic demands and/or for dynamic traffic scenarios. We present new theoretical results which demonstrate that traffic grooming with the Min-Max objective is NP-complete even when wavelength assignment is not an issue. We also present new polynomial-time traffic grooming algorithms for minimizing the maximum electronic port cost in both unidirectional and bidirectional rings. We evaluate our algorithms through experiments with a wide range of problem instances, by varying the network size, number of wavelengths, traffic load, and traffic pattern. Our results indicate that our algorithms produce solutions which are always close to the optimal and/or the lower bound, and which scale well to large network sizes, large number of wavelengths, and high loads. We also demonstrate that, despite the focus on minimizing the maximum cost, our algorithms also perform well in terms of the aggregate electronic port cost over all ring nodes.     

电信级以太网环网技术的研究

IP业务的快速发展使得网络中的业务流量逐渐从以时分复用（TDM）为主向以分组数据业务为主转换。为了适应这一转变,人们将低成本的以太网技术引入城域网络中,同时采用环网控制协议进行环形组网,利用环网保护技术来实现电信网络要求的可管理性及可靠性。ITU—TG．8032给出了以太环网的组网目标及定义,规范了电信级以太网（CE）环网技术。以太网环网保护技术（ERP）及弹性分组环技术（RPR）为两种不同的环网保护技术,而传送多协议标签交换（T—MPLS）网络中采用丁M—SPRing技术实现环网保护。运营商可以根据需求进行扩展,部署合适的环网技术,来满足电信级的要求。     

利用网络处理器构建弹性分组环模块

弹性分组环作为解决城域网的问题的一个方案被提出后,迅速成为研究的热点,但专用的RPR芯片还未商品化。提出了一种利用不支持RPR协议的网络处理器借助协议转换器来构建RPR模块的设计方案。协议转换器的主要功能是RPR/Ethernet帧转换和接口转换。文章介绍了RPR模块的结构和功能,并讨论了协议转换器的实现。     

RPR容错功能的可靠性分析

采用"网络连通率"作为度量网络可靠性的参数,通过对系统模型的数学解析,建立了具有源路由功能和回绕功能的弹性分组环的可靠性数学模型。通过数值分析,得出了环处理器故障率对系统可靠性的影响。     

弹性分组环中自动逻辑节点重新排序研究

弹性分组环(RPR)是一种新的城域网技术。在本文中通过假定一种RPR网络节点结构和对RPR公平性问题的分析,介绍了一种新的经济有效算法:逻辑节点重新排序法,并进行了实例分析。     

SDH自愈环的路由算法研究

本文分析了四纤双向共享保护环的几种业务路由算法，对各种算法所需的环路容量配置进行了计算机的随机统计模拟，基于上述模拟结果，讨论了用户接入网、局间中继网等网络所具有的不同业务分布模型与路由算法的关系，探讨了根据网络自身的业务特点选择业务路由算法的方法     

弹性分组环公平性算法的FPGA设计

随着弹性分组环的广泛使用，公平有效地利用有限的带宽资源尤为重要。文章主要介绍了公平性算法的FPGA设计，使其具有现实意义。     

A cost effective approach for survivable multicast traffic grooming in bidirectional multiwavelength ring networks

In this paper, we address the problem of survivable multicast traffic grooming in WDM bidirectional ring networks. The rapid growth of multicast applications such as video conferencing, distance learning, and online auction, has initiated the need for cost-effective solutions to realize multicasting in WDM optical networks. Many of these applications, being time critical and delay sensitive, demand robust and fault-tolerant means of data communication. The end user traffic demands in metro environment are in fractional bandwidth as compared to the wavelength channel capacity. Providing survivability at connection level is resource intensive. Hence cost-effective solutions that require minimum resources for realizing survivable multicasting are in great demand. In order to realize multicast traffic grooming in bidirectional ring networks, we propose a node architecture based on Bidirectional Add Drop Multiplexers (BADM) to support bidirectional add/drop functionality along with traffic duplication at each node. We also propose two traffic grooming algorithms, namely Survivable Grooming with Maximum Overlap of Sessions (SGMOS) and Survivable Grooming with Rerouting of Sessions (SGRS). Extensive simulation studies reveal that the proposed algorithms consume minimum resources measured in terms of BADM grooming ports, backup cost, and wavelengths.     

弹性分组环专用集成电路的可测性设计

根据弹性分组环专用集成电路的具体情况,提出了相应的可测性设计(Design for Test-ability,DFT)方案,综合运用了三种DFT技术:扫描链、边界扫描测试和存储器内建自测试。介绍了三种技术的选取理由和原理,对其具体实现过程和结果进行了详细分析。DFT电路的实现大大降低了专用集成电路的测试难度,提高了故障覆盖率。     

PROTECTORATION: a fast and efficient multiple-failure recovery technique for resilient packet ring using dark fiber

The two protection methods wrapping and steering used in IEEE 802.17 resilient packet ring (RPR) provide fast but very inefficient and limited network failure recovery. Due to the increased length of the backup path, RPR suffers from high traffic loss, a decreased throughput-delay performance, and the lack of resilience against multiple link and/or node failures. To achieve an improved resilience, interconnecting a subset of the ring nodes by means of a dark-fiber single-hop star wavelength division multiplexing (WDM) network is proposed. In doing so, the ring network is divided into separate domains, each being fully recoverable from a single link or node failure without losing full network connectivity. A novel hybrid fault recovery technique, termed protectoration, is proposed and examined by means of probabilistic analysis and simulation in terms of stability, channel utilization, and throughput-delay performance. The proposed protectoration technique 1) combines the fast recovery time of protection and the bandwidth efficiency of restoration, 2) provides full recovery from multiple link and node failures, 3) builds on both wrapping and steering protection methods of RPR and, thus, allows for an evolutionary upgrade of existing RPR networks, and 4) does not require the convergence of routing protocols in response to failures and, thus, improves the routing stability and network availability. Numerical investigations in this paper show that the location of failures has a strong impact on the network performance. For a given failure location, the protectoration technique is able to accommodate multiple ring failures without significant performance loss.     

弹性分组环高生存性垂直拓扑的研究

文章提出一种基于弹性分组环(RPR)的新型环网拓扑结构.该结构采用环网垂直的拓扑方式,拥有较高的生存性,同时,又充分利用了RPR标准单环数据传输机制的优点,并将该优点应用到宏观的网络体系结构中,提高了网络整体的带宽利用率.     

高生存性RPR网络数据传输实现

单环的RPR网络虽具有很多优点,但是其生存性不高.在此提出一种高生存性的RPR网络结构,为实现这种网络结构,我们对RPR标准帧格式中的R/P位进行了扩展定义,用计算机对最简单的高生存性RPR网络进行了仿真,成功地实现了跨环的数据传输.