在路由器上实现IP实时传真业务

文章所介绍的在路由器上实现实时传真业务主要利用路由器先前开发的Voiceover IP功能，通过运用硬件芯片的富余功能和开发先进的T38协议并扩展H．323协议来实现，即不增加路由器设备的成本，又为购买路由器的用户提供了一个非常有用的功能。     

高性能IPv4/v6双栈路由器邻居表管理设计与实现

T比特路由器是IPv4/v6双协议栈路由器,因此邻居表的管理分别包括对Lirux内核空间和用户空间的IPv4/v6两种邻居表的管理.本文给出了一种利用Linux操作系统内核中提供的Netlink通信机制实现邻居表管理的方案,方案分析和功能测试的结果表明,该方案可以对T比特路由器中的IPv4/v6双协议栈邻居表进行有效管理.     

基于SSL协议与SSH的远登录模型研究

本文针对远程登录到路由器或交换机进行设备监控与维护的过程中传输的数据容易被窃取、登录用户无法认证、用户操作的日志信息无法记录等问题提出了一种基于SSL协议和SSH服务（Linux系统服务）的远程维护和管理网络设备的方法。在此基础上提供了一种C／S模式的Java实现,能够实现用户信息认证、用户数据的安全传输和用户日志的记录。     

分布式路由器操作维护管理系统的设计与实现

路由器操作维护管理（OAM）系统负责对路由器进行操作和管理,它是由路由器正常运行的保证,是路由器中的重要模块。高性能路由器通常采用的分布式体系结构,这就对操作维护管理提供了新的要求。本文对路由器操作管理进行了深入的研究,首先介绍了路由器操作管理的设计要求和研究现状,然后介绍了清华大学研制的高性能多协议路由器的软硬件体系结构和其对操作维护管理系统的功能要求,设计并实现了面向分布式路由器的操作维护管理系统。最后总结了全文并指出了进一步研究方向。     

RIP和OSPF路由协议在Click软件路由器中的实现

Click是一种模块化的软件路由器体系结构,基于该体系结构用户可以根据自己的需求搭建不同功能的路由器.针对Click软件路由器支持静态路由协议的局限性,引入模块化路由器软件协议栈XORP(eXtensible Open Router Platform),实现了动态路由协议在Click软件路由器上的扩展.通过搭建实验网络拓扑环境,验证了基于Click转发平台的两种不同的动态路由协议RIP和OSPF,并进行了相关测试和性能分析.实验结果表明,Click软件路由器的转发性能与Linux内核基本一致,但相比较而言,Click软件路由器具有灵活、可扩展、模块化等不可比拟的优势.     

串口通讯在全光智能光波长路由器中的应用

主要介绍了串口通讯在全光智能光波长路由器控制平面中的应用。该光波长路由器利用VC++6.0中的MSComm控件在计算机上进行串口通讯管理。并对系统串行通讯体系、串口通讯协议的设计、串口通讯软件实现等方面进行了论述。     

试论路由器的安全配置与安全维护

正确配置路由器,有效维护好路由器,确保其安全性是至关重要的。本文从访问控制、网络服务、路由协议、防止攻击及防止病毒等方面详细介绍了路由器的具体安全配置要求,并探讨了路由器安全维护的具体措施。     

刀片服务器——挑战密度极限

机架式服务器以其节省空间、高密度、便于集中维护、管理等优势得到了用户普遍的认可。但用户对机架服务器高度的追求,到了1U就似乎已经到了尽头,如果您的机柜空间告急,机柜里已经充满了配线架、路由器,交换机、集线器、各种高度的服务器、输入／输出设备共享器,如何再添置服务器来满足日益增长的业务需求?除了增加机柜以外,还有比1U服务器密度更高的选择,“刀片”服务器就是其中之一。所谓刀片服务器是指在标准高度的机架式机箱内可插装多个卡式的服务器单元,实现高可用和高密度。最近,《微电脑世界》技术应用实验室收到了网虎公司的一款刀片服务器,我们对基于该服务器的各种应用进行了实践,并对其应用模式进行了探讨。     

基于Android平台的风机手持操作仪开发

基于Android平台开发了一款风机手持操作仪, 用于风机的日常监视、维护及设置。以TCP/IP协议和MODBUS协议为基础, 与风机主控系统实现基础数据通讯, 并通过交互界面上的触控操作来完成监视、维护及设置功能; 同时, 利用数据库技术实现对风机和用户数据的存储与管理, 并对用户关键信息进行加密处理以提升安全性。实际应用表明了该设备的可行性、有效性, 并且具备灵活、便携、经济等特点。     

多屏终端在路由器上的设计和实现

终端服务器主要提供终端接入功能；而路由器主要是完成数据的路由和转发功能。在路由器上实现终端服务器的功能，可以减少整个网络的设备并简化设备的连接，方便维护。在提供终端服务功能的同时提供多屏功能，将大大加强终端服务的功能，并适应一些新的应用需求。该文设计的一套协议和与其结合的多屏模块一起，有效地解决了上述两个技术课题。并在路由器上加以实现，在实际的使用中取得了很好的效果。     

基于串空间理论的安全协议自动验证

针对目前串空间理论依赖分析人员主观判断、无法使用自动化工具进行验证的问题,提出了基于串空间理论的协议认证属性标准化验证过程。首先为协议消息项定义类型标签,对串空间及认证测试理论进行扩展;然后通过判断测试元素出现位置、检验测试元素参数一致性、确认变换进行边唯一存在性和检验目标串参数一致性,将基于串空间理论的协议验证过程标准化为可程序实现的步骤。该算法的时间复杂度为O(n²),避免了模型检测方法的状态空间爆炸问题,并在此基础上实现了安全协议认证属性的自动化验证工具。以BAN-Yahalom协议和TLS 1.0握手协议为例进行了标准化的分析验证,找到了对BAN-Yahalom协议的一种新攻击形式。该攻击无需限制服务器对随机数的检查,比Syverson发现的攻击更具普遍性。     

A distributed chromosome genetic algorithm for bin-packing

Genetic algorithms (GAs) are excellent approaches to solving complex problems in optimization with difficult constraints. The classic bin-packing optimization problem has been shown to be a NP-complete problem. The loading multiple parts into the build cylinder of a rapid prototyping machine is a type of a bin-packing optimization problem. There are GA applications that work with variations of the bin-packing problem, such as stock cutting, vehicle loading, air container loading, scheduling, and knapsack problems. These applications are mostly based on one-dimensional or two-dimensional considerations, using very specific assumptions. Ikonen et al. (A genetic algorithm for packing three-dimensional non-convex objects having cavities and holes. In: Proceedings of the Seventh International Conference on Genetic Algorithms. Michigan State University, July 19–23, 1997.) have developed a GA for rapid prototyping called GARP, which utilizes a three-dimensional chromosome structure for the bin-packing of a Sinterstation 2000s build cylinder. GARP allows the Sinterstation 2000 to be used more productively by designing a packing method for multiple parts. GARP was developed using a sequential GA, so execution time is influenced by the number of parts to be packed. Anticipating greater use of time compression technologies, GARP's execution time needs to be reduced. This paper will detail the development of a distributed chromosome GA to reduce the execution time of GARP. The implementation of this distributed GA will improve the efficiency of GARP, by using multiple CPUs to help solve the problem of bin-packing the build cylinder for the rapid prototyping machine.     

Distributed Version Management for Read-Only Actions

Typical concurrency control protocols for atomic actions, such as two-phase locking, perform poorly for long read-only actions. We present four new concurrency control protocols that eliminate all interference between read-only actions and update actions, and thus offer significantly improved performance for read-only actions. The protocols work by maintaining multiple versions of the system state; read-only actions read old versions, while update actions manipulate the most recent version. We focus on the problem of managing the storage required for old versions in a distributed system. One of the protocols uses relatively little space, but has a potentially significant communication cost. The other protocols use more space, but may be cheaper in terms of communication.     

PASES: An energy-aware design space exploration framework for wireless sensor networks

Energy consumption is one of the most constraining requirements for the development and implementation of wireless sensor networks. Many design aspects affect energy consumption, ranging from the hardware components, operations of the sensors, the communication protocols, the application algorithms, and the application duty cycle. A full design space exploration solution is therefore required to estimate the contribution to energy consumption of all of these factors, and significantly decrease the effort and time spent to choose the right architecture that fits best to a particular application. In this paper we present a flexible and extensible simulation and design space exploration framework called “PASES” for accurate power consumption analysis of wireless sensor networks. PASES performs both performance and energy analysis, including the application, the communication and the platform layers, providing an extensible and customizable environment. The framework assists the designers in the selection of an optimal hardware solution and software implementation for the specific project of interest ranging from standalone to large scale networked systems. Experimental and simulation results demonstrate the framework accuracy and utility.     

安全多方计算在空间几何问题中的应用

研究安全多方计算在空间几何问题中的应用,提出了空间中基于阈值的两点之间、点线之间距离关系的保密判定协议,空间中点与两平行平面位置关系的保密判定协议;并利用这些协议作为子协议为空间中基于阈值的点与线段之间距离关系的保密判定问题构造了相应的保密解决方案.所提出的协议和解决方案在工程、商业和军事等领域中具有潜在的应用价值.     

A network infrastructure for IP mobility support in metropolitan areas

The original design of the Internet and its underlying protocols did not anticipate users to be mobile. With the growing interest in supporting mobile users and mobile computing, a great deal of work is taking place to solve this problem. For a solution to be practical, it has to integrate easily with existing Internet infrastructure and protocols, and offer an adequate migration path toward what might represent the ultimate solution. In that respect, the solution has to be incrementally scalable to handle a large number of mobile users and wide geographical scopes, and well performing so as to support all application requirements including voice and video communications and a wide range of mobility speeds. In this paper, we present a survey of the state-of-the-art and propose a scalable infrastructure to support mobility in Internet protocol networks. In that respect, we exploit local area network (LAN) technologies to create the network infrastructure necessary to offer connectivity to mobile users across any geographical area (building, campus and metropolis). The intrinsic properties of LAN technologies and their underlying protocols, namely flat address space, transparent learning and low complexity renders this solution particularly cost effective for supporting user mobility. In particular, we propose a network topology and a set of protocols that render the infrastructure scalable to a large geographical area and many users.     

The Impact of Symmetry on Software Distributed Shared Memory

A homeless protocol is one in which all nodes are treated identically when they access common resources. By contrast, home-based protocols assign a home or manager to each resource. Use of the resource by the home incurs less overhead than use by other processors. The key to good performance in such systems is to ensure that the asymmetry of the underlying protocol is skewed in the same way as that of the application. This paper presents a comparative evaluation of invalidation-based homeless and home-based software DSM protocols. We pay particular attention to those performance differences caused by symmetric and asymmetric features of the protocols. We then show how the picture changes when update protocols are targeted. We show that a modified home-based protocol can significantly outperform more general protocols in this application domain because of reduced protocol complexity. We further optimize our protocol by completely eliminating such memory manipulation calls from the steady-state execution. Our resulting protocol improves average application performance by a further 34%, on top of the 19% improvement gained by our initial modification of the home-based protocol.     

基于下一代互联网的IPv6路由协议研究

IPv6是下一代互联网发展的基石,它解决了IPv4存在的一些问题和不足,同时还在许多方面进行了改进,如路由协议、QoS和支持移动性等,并大大增加了地址空间。RIPng和OSPFv3等协议是基于IPv6的主要路由技术,目前大多数互联网用户使用IPv4协议,深入开展IPv6在下一代互联网的应用研究具有重要意义。     

An Efficient Partial Order Reduction Algorithm with an Alternative Proviso Implementation

This paper presents a partial order reduction algorithm called Twophase that generates a significantly reduced state space on a large class of practical protocols over alternative algorithms in its class. The reduced state-space generated by Twophase preserves all CTL*-X assertions. Twophase achieves this reduction by following an alternative implementation of the proviso step. In particular, Twophase avoids the in-stack check that other tools use in order to realize the proviso step. In this paper, we demonstrate that the in-stack check is inefficient in practice, and demonstrate a much simpler alternative method of realizing the proviso. Twophase can be easily combined with an on-the-fly model-checking algorithm to reduce memory requirements further. A simple but powerful selective caching scheme can also be easily added to Twophase.A version of Twophase using on-the-fly model-checking and selective caching has been implemented in a model-checker called PV (Protocol Verifier) and is in routine use on large problems. PV accepts a proper subset of Promela and a never automaton expressing the LTL-X assertion to be verified. PV has helped us complete full state-space search several orders of magnitude faster than all alternative tools available in its class on dozens of real protocols. PV has helped us detect bugs in real Distributed Shared Memory cache coherency protocols that were missed during incomplete search using alternate tools.     

面向电力系统实时通信的应用层数据网关模型的设计

本文针对电力系统采用不同应用层协议通信,阻碍信息交换与共享的现状,提出一种面向电力系统实时通信的应用层数据网关模型。该模型成功地实现了信息在不同应用层协议间的传递、将分布在不同调度系统的实时数据及非实时数据通过远程网络统一管理起来。