Optimal redundancy allocation for high availability routers

How to optimally allocate redundant routers for high availability (HA) networks is a crucial task. In this paper, a 5‐tuple availability function A (N, M, λ, µ, δ) is proposed to determine the minimum required number of standby routers to meet the desired availability (ρ) of an HA router, where N and M are the numbers of active routers and standby routers, respectively, and λ, µ, and δ are a single router's failure rate, repair rate, and failure detection and recovery rate, respectively. We have derived the availability function, and analytical results show that the failure detection and recovery rate (δ) is a key parameter for reducing the minimum required number of standby routers of an HA router. Thus, we also propose a High Availability Management (HAM) middleware, which was designed based on an open architecture specification, called OpenAIS, to achieve the goal of reducing takeover delay (1/δ) by stateful backup. We have implemented an HA Open Shortest Path First (HA‐OSPF) router, which consists of two active routers and one standby router, to illustrate the proposed HA router. Experimental results show that the takeover delays of the proposed HA‐OSPF router were reduced by 6, 37.3, and 98.6% compared with those of the industry standard approaches, the Cisco‐ASR 1000 series router, the Juniper MX series router, and the Virtual Router Redundancy Protocol (VRRP) router, respectively. In addition, in contract to the industry routers, the proposed HA router, which was designed based on an open architecture specification, is more cost‐effective, and its redundancy model can be more flexibly adjusted. Copyright © 2010 John Wiley & Sons, Ltd.     

Integrating bridges and routers in a large internetwork

A review is presented of the principal functional characteristics of routers and bridges, particularly as they relate to the construction of large-scale internetworks. The discussion of bridges covers filtering performance, forwarding performance, packet latency, adaptability, internetwork topology, network management, security transparency, and multiway and fault-tolerant bridges. The discussion of routers covers network layer protocols, internetwork size, static versus dynamic routing, routing information updates, network management, routing optimizations, session survivability, contamination containment, routing optimization, and load sharing     

Detecting compromised routers via packet forwarding behavior

While it is widely understood that criminal miscreants are subverting large numbers of Internet-connected computers (e.g., for bots, spyware, SPAM forwarding), it is less well appreciated that Internet routers are also being actively targeted and compromised. Indeed, due to its central role in end-to-end communication, a compromised router can be leveraged to empower a wide range of direct attacks including eavesdropping, man-in-the-middle subterfuge, and denial of service. In response, a range or specialized anomaly detection protocols has been proposed to detect misbehaving packet forwarding between routers. This article provides a general framework for understanding the design space of this work and reviews the capabilities of various detection protocols.     

一种网间异常流量诊断处置方案

针对中国移动部分IDC客户违规转租带宽、发展第三方家宽、内容资源调度策略不合理而造成大量回源流量从CMNET骨干网出口疏通的网间异常流量行为,提出一种基于深度报文检测技术(DPI)技术的诊断处置方案。方案已成功应用于移动某省公司的IDC客户异常流量的诊断处置, IDC业务CMNET骨干网出口网间流量下降71.42%、减少经济损失,出口质量显著提高,异常流量行为显著减少、风险得以有效防控。     

一种基于Openstack的虚拟机高可用方案

针对Openstack的高可用性问题,目前大部分的研究都集中在控制节点的高可用上,对于虚拟机的高可用研究较少.已有的虚拟机高可用方案存在无法适应多种故障场景、无法针对单个虚拟机粒度进行故障处理等问题.本文提出了一种基于Openstack的虚拟机高可用方案,方案使用控制组件和代理服务组件,配合不同故障的检测逻辑,实现多种...     

A software support infrastructure for wireless access routers

Routers are expected to play an important role in the Internet protocol-based wireless data network. Although a substantial number of adaptive and intercell coordination techniques have been proposed to improve wireless network performance under dynamic wireless channel conditions and host mobility, a system support framework is still missing. In this paper, we describe DIRAC, a software-based router system that is designed for wireless networks to facilitate the implementation and evaluation of various channel-adaptive and mobility-aware protocols. DIRAC adopts a distributed architecture that is composed of two parts: a router core (RC) shared by the wireless subnets, and a router agent (RA) at each access point/base station. RAs expose wireless link-layer information to the RC and enforce the control commands issued by the RC. This approach allows the router to make adaptive decisions based on link-layer information feedback on both data and control planes. It also permits the router to enforce its policies (e.g., policing) more effectively through underlying link-layer mechanisms. It further enables interaccess-point coordination at the RC. As showcases, we implement under DIRAC the prototypes of three wireless network services: link-layer assisted fast handover, channel-adaptive scheduling, and link-layer enforced policing. Our implementation and experiments show that our distributed wireless router provides a flexible framework, which enables advanced network-layer wireless services that are adaptive to channel conditions and host mobility.     

A proposed design for ultralow-loss waveguide grating routers

We propose a design for a dense wavelength-division multiplexing (WDM) demultiplexer whose total fiber-to-fiber insertion loss can be as low as 0.3881 dB. Our three dimensional (3-D) models-beam propagation and mode solver-show that waveguide bending losses and fiber coupling losses are almost insignificant. Most of the loss comes from the star couplers and from material losses     

A study of fiber-to-fiber losses in waveguide grating routers

Most of the waveguide grating router's loss comes from fiber coupling and star coupler. Our three-dimensional (3-D) models quantifies both losses. In addition, we study how various waveguide parameters affect the value and nonuniformity of this loss. Our optimization yields a design where the total fiber-to-fiber insertion loss can be reduced to 0.535 dB     

浅析双机系统的高可用性

介绍了部署实施双机系统的能力基础和技术基础,阐述了双机系统工作的原理、集群管理工作原理和最基本的双机架构模式,提出了双机环境前期设计和规划的建议。     

数据中心高可用性网络设计

数据中心是企业信息化业务承载的平台,随着信息化建设的深入,数据中心的建设及运维给信息部门带来了巨大的压力。针对数据中心网络建设问题,分析了高可用性网络的度量,提出了通过采用虚拟化、故障检测等技术结合网络划分的模块化网络设计,提高了网络的安全性和可用性,满足了企业信息业务的发展。     

高轨GPS信号可用性分析

针对目前国内关于高轨GPS信号可见性研究大多以几何分析为主,工程实现指导性不强的缺点,文章以GPS接收机系统指标设计为目标,引入接收机等价增益概念,结合空间几何模型与信号链路传播特点,考虑GPS发射天线增益、接收机信号处理时间、GPS星座状况、接收天线增益等实际因素,对适用于高轨GPS信号可用性进行分析。仿真表明-180 dBW接收功率下,通过接收更多GPS旁瓣信号,GPS接收机能有效应用于高轨航天器导航。     

Design and implementation of Single-Buffered routers

A Single-Buffered （SB） router is a router where only one stage of shared buffering is sandwiched between two interconnects in comparison of a Combined Input and Output Queued （CIOQ） router where a central switch fabric is sandwiched between two stages of buffering. The notion of SB routers was firstly proposed by the High-Performance Networking Group （HPNG） of Stanford University, along with two promising designs of SB routers： one of which was Parallel Shared Memory （PSM） router and the other was Distributed Shared Memory （DSM） router. Admittedly, the work of HPNG deserved full credit, but all results presented by them appeared to relay on a Centralized Memory Management Algorithm （CMMA） which was essentially impractical because of the high processing and communication complexity. This paper attempts to make a scalable high-speed SB router completely practical by introducing a fully distributed architecture for managing the shared memory of SB routers. The resulting SB router is called as a Virtual Output and Input Queued （VOIQ） router. Furthermore, the scheme of VOIQ routers can not only eliminate the need for the CMMA scheduler, thus allowing a fully distributed implementation with low processing and commu- nication complexity, but also provide QoS guarantees and efficiently support variable-length packets in this paper. In particular, the results of performance testing and the hardware implementation of our VOIQ-based router （NDSC~ SR1880-TTM series） are illustrated at the end of this paper. The proposal of this paper is the first distributed scheme of how to design and implement SB routers publicized till now.     

加大政府监管力度 确保网间通信安全畅通

前不久,信息产业部政策法规司司长蒋耀平在题为《我国信息的发展与政策分析》的讲话中提出:“加大政府监管力度,确保网间通信安全畅通”。蒋耀平司长的讲话共分三个问题:(一)信息产业的发展现状;(二)信息产业发展过程中采取的主要政策和措施;(三)2003年信息产业发展的主要措施。“加大政府监管力度,确保网间通信安全畅通”是在他讲话的第三个问题中提出的。蒋司长指出,为贯彻落实十六大精神,发挥信息产业的战略性作用,使之在全面建设小康社会中担负起重要的历史使命,2003年我们将采取十一个措施:(1)加强对行业发展的规划指导;(2)加强对业务…     

A framework for optimizing the cost and performance ofnext-generation IP routers

The explosive growth of Internet users, the increased user demand for bandwidth, and the declining cost of technology have all resulted in the emergence of new classes of high-speed distributed IP-router architectures with packet-forwarding rates of the order of gigabits, or even terabits, per second. This paper develops an analytical framework for modeling and analyzing the impact of technological factors on the cost-performance tradeoffs in distributed-router architectures. The main tradeoff in a distributed router results naturally from moving the main packet-forwarding and processing power from a centralized forwarding engine to an ensemble of smaller forwarding engines, either dedicated to or shared among the line cards. Processing packets in these smaller engines can be much cheaper (by as much two to three orders of magnitude) than in a centralized forwarding engine. Therefore, the main goal of our modeling framework is to determine an optimal allocation of processing power to the forwarding engines (in a distributed router) to minimize overall router cost while achieving a given level of packet-forwarding performance. Two types of router models are analyzed using the proposed framework: a distributed-router architecture and parallel-router architecture     

A novel IP-routing lookup scheme and hardware architecture formultigigabit switching routers

One of the pertinent design issues for new generation IP routers is the route-lookup mechanism. For each incoming IP packet, the IP routing is required to perform a longest-prefix matching on the route lookup in order to determine the packet's next hop. This study presents a fast unicast route-lookup mechanism that only needs tiny SRAM and can be implemented using a hardware pipeline. The forwarding table, based on the proposed scheme, is small enough to fit into a faster SRAM with low cost. For example, a large routing table with 40000 routing entries can be compacted into a forwarding table of 450-470 kbytes costing less than US$30. Most route lookups need only one memory access; no lookup needs more than three memory accesses. When implemented using a hardware pipeline, the proposed mechanism can achieve one routing lookup every memory access. With current 10-ns SRAMs, this mechanism furnishes approximately 100×10⁶ routing lookups/s, which is much faster than any current commercially available routing-lookup scheme     

基于SAF规范的高可用电信中间件设计

保证在软硬件出现故障后系统还能不间断地提供服务,是电信系统高可用性研究的重点.为了增强系统的可用性,在服务可用论坛提出的中间件规范基础之上设计了一个中间件系统基本框架,对集群通信服务、集群平台服务、可用性管理服务、通用服务进行了高可用设计,该中间件提供了兼容服务可用论坛的接口,采用该中间件系统构建电信应用软件时,开发者只需要集中精力到具体业务开发方面,而不需要过多关注集群可用性、性能等特性.最后,对该系统的可用性进行了测评,实验数据表明该中间件完全满足电信高可用性的要求.     

Compression of multicast labels in large IP routers

In small cell-based Internet protocol routers, multicast traffic is generally handled by appending to each cell a local multicast label (LML) containing a bitmap with as many bits as switch ports, so as to identify the ports to which a copy of the cell has to be transferred. This approach is not feasible for switches having 128 ports or more, because the LML length would rise above 16 bytes, thus representing an intolerable overhead, given the small size of cells (typically 64 bytes). We discuss both static and adaptive lossy compression algorithms to reduce the size of LMLs to be attached to multicast cells, at the price of the delivery of cells to a larger set of outputs than necessary, and we compare the compression algorithms performance in terms of switch bandwidth waste, using both analytical and simulation models.     

SQLServer数据库高可用性方案的研究和实践

针对台内各项业务系统对数据库的高度依赖,苏州广电总台依据实际情况,设计了一套双机群集再镜像的高可用数据库系统,在苏州台媒资系统中实施,取得了良好的效果.主要介绍了该系统的设计目标、拓扑结构和系统特点.     

基于离散预约速率与分组长度组结构的高速路由器公平队列调度算法实现

本文提出一种基于离散预约速率与分组长度组单元的公平隐列调度器实现结构,该结构可根据不同预约速率需求,为其方便灵活的提供不同的预约带宽实现精度。组单元的模块化设计结构与流水线设计技术使得硬件逻辑资源得到更有效的利用。文中同时提了一种适用于结构的定点时标重构技术,利用该技术可有效节约存储流时标的所需的外部存储空间,算法仿真与FPGA综合结果表明,该结构可支持1．2Gbit/s 的输出链路,通过有效的集成方式,该设计可进一步应用到端口速率为OC－48（2．4Gbps)的高速路由器中。l