一种增强RTP协议可扩展性的算法

支持Internet多媒体服务的RTP协议已得到广泛应用,但在大规模、动态可变的会话系统中,协议的控制部分RTCP存在容易引起拥塞等可扩展性问题,已有的算法还不能解决RTCP BYE报文泛滥所导致的拥塞,本文研究了引起拥塞的内在原因,提出了一种改进算法以避免RTCP BYE报文的泛滥,从而增强了RTP协议的可扩展性,文中还给出了模拟实验的结果,并对其进行了分析。     

反向业务流对TCP性能的影响研究

简要分析了TCP协议的拥塞控制机制,指出在网络中存在较大反向业务流时会对TCP业务产生严重的影响,通过仿真实验对TCP拥塞控制机制的3种拥塞控制算法:Reno算法,SACK算法和Vegas算法在存在大量反向业务流情况下的表现进行了比较,分析了它们性能下降的原因,提出了改进设想,为解决TCP拥塞问题提供了新的思路。     

Checking safety properties on-the-fly with the sweep-line method

The sweep-line state space method allows states to be deleted from memory during state exploration, thus alleviating the state explosion problem. Properties of the system (such as the absence of deadlocks) can then be verified on-the-fly. This paper presents an extension to the sweep-line method that allows on-the-fly checking of safety properties expressed as sequences of actions of the modelled system. This has been implemented in a prototype sweep-line library for Coloured Petri nets. We evaluate the prototype by applying it to the connection management procedures of the Datagram Congestion Control Protocol, a new Internet transport protocol. This paper was supported by Australian Research Council Discovery Grants DP0210524 and DP0559927. L. M. Kristensen was supported by the Carlsberg Foundation and the Danish Research Council for Technology and Production.     

基于ADAMS与Simulink的协同仿真技术及应用

基于多学科协同建模与协同仿真的虚拟样机技术,已经成为现代复杂产品设计的一个重要手段,文中主要对ADAMS与Simulink之间的协同仿真技术进行介绍。通过分析协同仿真实现方式和两者提供的外部接口,探讨了ADAMS与Simulink进行协同仿真的若干种方法,实现了两者在单机环境和网络环境下的交互式协同仿真,并以一个五自由度转台的控制器设计为例,验证了这些协同仿真方法的可行性和实用性。支持网络环境下的远程协同仿真技术为跨区域的多领域部门之间进行产品协同设计提供了便利,是工程仿真软件发展的一个重要方面。     

新一代的拥塞控制机制-XCP的研究

算法和分析表明,随着带宽延迟的增加,不管采用何种队列调度策略,TCP都变得不稳定和难于收敛.提出了一种新的拥塞控制机制-XCP(eXplicit Control Protocol),一个比TCP更加有效和公平的拥塞控制协议,并在模拟的环境中对XCP和TCP协议的性能进行了分析和比较.     

校园网络拥塞控制研究和对策

本文研究校园网络的拥塞控制问题,从技术和用户两个层面分析校园网络发生拥塞的原因,结合校园网络的实际情况,主要从流量控制的角度研究解决校园网络拥塞问题的一些对策和建议     

TreeView树结构动态绑定在ASP.NET 2.0中的应用

TreeView作为ASP.NET 2.0的服务器组件使得网站页面导航功能更为强大,但常规的静态绑定树结构,使得其在使用上受到一定限制.利用数据库动态查询,动态添加绑定树结构,无疑为TreeView的使用另辟蹊径.动态绑定多层次TreeView树结构,使得TreeView的导航功能更加灵活方便.     

基于NS-2的Drop-Tail与RED算法仿真研究

队列管理是网络拥塞控制和服务质量保证的基石,Drop-Tail和RED算法是两种典型的队列管理算法。本文分析了两种队列管理算法的原理及优缺点,基于NS-2仿真模拟器对两种算法进行了模拟,从队列长度、TCP拥塞数据窗口、吞吐量、丢包率四个指标对两种算法进行了分析比较。     

A new congestion control algorithm for improving the performance of a broadcast-based multiprocessor architecture

Congestion occurring in the input queues of broadcast-based multiprocessor architectures can severely limit their overall performance. The existing congestion control algorithms estimate congestion based on a node’s output channel parameters such as the number of free virtual channels or the number of packets waiting at the channel queue. In this paper, we have proposed a new congestion control algorithm to prevent congestion on broadcast-based multiprocessor architectures with multiple input queues. Our algorithm performs congestion control at the packet level and takes into account the next input queue number which will be accessed by the processor, which form the fundamental differences between our algorithm and the algorithms based on the idea of virtual channel congestion control. The performance of the algorithm is evaluated by OPNET Modeler with various synthetic traffic patterns on a 64-node Simultaneous Optical Multiprocessor Exchange Bus (SOME-Bus) architecture employing the message passing protocol. Performance measures such as average input waiting time, average network response time and average processor utilization have been collected before and after applying the algorithm. The results show that the proposed algorithm is able to decrease the average input waiting time by 13.99% to 20.39%, average network response time by 8.76% to 20.36% and increase average processor utilization by 1.92% to 6.63%. The performance of the algorithm is compared with that of the other congestion control algorithms and it is observed that our algorithm performs better under all traffic patterns. Also, theoretical analysis of the proposed method is carried out by using queuing networks.     

基于TCP的拥塞控制算法研究综述

随着互联网规模的增长,互连网上的用户和应用都在快速的增长,拥塞已经成为一个十分重要的问题。近年来,在拥塞控制领域开展了大量的研究工作。此文介绍了基于TCP协议的拥塞控制算法的研究现状,分析了对算法改进的研究,并提出一些改进的建议。