基于信令降频方法的光纤交换网通信协议FCSP-RTF的研究

针对集群等通信中需频繁使用控制帧系统的网络通信需求,设计了一种基于信令降频方法的高效光纤交换网通信协议FCSP-RTF(the high-speed Fibre Channel Switch Protocol based on Reducing the Token's Frequency ).该通信协议在"信令寻径"技术的基础上对信令帧进行降频编码,使交换机无需降频器件就能够直接识别高频信令信号,高效完成交换工作;FCSP-RTF协议精简了通信帧格式,提高了通信协议的效率.实验结果显示,FCSP-RTF协议帧结构简单,实现容易,基于此协议的千兆光纤交换网通信效率和可靠性高,实现成本大大降低.     

基于信令降频码方法的信令寻径式光纤交换机的研究

信令寻径式高速光纤交换机需要使用大量"串/并"转换器件提取信令来实现对信道的控制,这使得交换机的底板面积十分庞大,无法检测BGA封装焊接质量;针对以上问题,提出了一种使用特殊的降频码对信令进行编码,成倍地降低信令的频率,采用普通的FPGA器件即可提取信令,取代了大量占线的"串/并"转换器件,减少了PCB面积和降低了成本;并在此基础上给出了高速光纤交换机的解决方案;目前,基于信令降频码方法的信令寻径式光纤交换机已经调试成功,性能稳定,运行状态良好。     

信令寻径式高速光纤传输交换机研究与设计

针对未来航电系统需求,研究一种新型的以“信令寻径式交换技术”为核心的高速光纤传输交换网络。该文设计了信令寻径式交换网络通信协议,并在此基础上详细论述了高速光纤传输交换机设计方案。目前,16端口的信令寻径式高速光纤传输交换机已初步调试成功,性能稳定,运行状况良好,可应用于航电和中尺度天气预报等高速网络通信系统中。     

公共信道信令

在内部交换网络上用户连结的建立、操作、终止,网络资源的管理,智能网络服务的提供,要求在内部交换网络中本地与传输交换机之间交换控制信号,在网络智能存贮器之间交换控制信号。在绝大多数远程通信网络中,这种信令是在传输用户信息的线路上传递的。为此,所需的信道容量,既可以永久地安排一部分线路容量给信令,也可以在某一段     

基于七号信令的收入保障系统

目前我国电信行业的收入体系是对采集到的交换机原始话单进行计费来实现的,采集点分散、实时性差,交换系统所提供的原始话单接口的复杂多变使得计费收入得不到充分保障.介绍一种基于七号信令的收入保障系统,在信令链路上实时获取话务控制的信令信息,再对信令信息分析处理后形成信令话单,该话单与计费的原始话单的比对和校验来确保计费收入的正确和完备.系统具有实时性高、容量大、可靠性强等特点,有效解决了电信运营商的收入保障问题.     

ATM接入交换机信令软件的设计与实现

ATM接入交换机是实现传统局域网与ATM网络互连的一种关键设备,它所采用的信令是UNI信令。本文重点介绍了在接入交换机中采用的信令技术,给出了ATM信令模块的设计与实现,并给出了重点函数的算法流程。     

面向机群系统的高速光纤传输网络接口卡设计

针对机群系统的通信瓶颈问题,研究一种新型的以“信令寻径式交换技术”为核心的高速光纤传输交换网络。本文分析了信令寻径式交换网络通信协议,在此基础上设计并实现了基于光纤通道技术的高速网络接口卡。该网卡针对大小数据包的特点,分别对各种类型的帧进行专门设计,具有较高的通信效率。测试结果表明,由该网络接口卡组成点对点网络,其单向传输延时为4.22µs,通信带宽高达993.8Mbps,最大链路利用率为93.53％。目前,该网络接口卡性能稳定,运行状况良好,能满足机群系统通信需要。     

ATM UNI信令协议的研究

ＡＴＭ技术是一种基于连接的网络技术。网络中任何两点在交换信息之前，都必须建立相应的虚连接。ＡＴＭ ＵＮＩ信令协议是研究ＡＴＭ网络的端节点和交换机之间建立，维护，释放，管理虚连接的协议规范。     

基于SIP的信令安全网关安全模块

GB/T 28181标准制定了安全防范视频监控联网系统信息传输、交换、控制技术要求,其中信令安全路由网关是一种应用服务器,负责接收或转发域内外SIP信令,完成信令安全路由网关间信令身份标识的添加和鉴别等功能. 本文通过分析GB/T28181标准中信令安全网关的基本功能需求,提出信令安全网关安全模块的设计方案. 它通过对域内外转发的信令进行加解密和数字签名操作实现了身份认证、信息保密性和完整性的安全保障. 通过实际运行测试出此设计方案具有较好的性能和稳定性.     

软交换信令网关实现技术的探索

由于SIP协议与H. 323协议之间的非对称性,使软交换信令网关在实现时将不可避免地遇到一些困难。对软交换信令网关中的呼叫建立、信令转换、媒体逻辑信道建立和媒体会话能力交换等一些基本问题进行探讨,并就地址转换、信令转换的一致性等问题提出相应的解决方法,为软交换中信令网关的设计和实现提供了一种思路。     

光纤通道交换机体系结构的设计

由于光纤通道的高速性,光纤通道交换机面临着现有普通交换机设计没有的问题.针对这些问题,从体系结构的选择,交换机的组成框架.主要部件的功能和结构等方面论述扣分析了光纤通道交换机硬件的总体设计.     

Performance investigation of a token passing access protocol for a multichannel optical fibre LAN

An alternative approach to multichannel local area network access is described. The new multichannel access scheme or protocol is based on a token passing arbitration policy. It is specifically intended for use with a starconfigured optical fibre LAN employing wavelength division multiplexing technology in order to provide a multichannel transmission medium. The multichannel network architecture comprises a single reservation channel and several equivalent speed data channels. Delay versus throughput performance characteristics for the network obtained by both analysis and discrete event simulation are shown. The multichannel token passing protocol is found to significantly improve these characteristics in comparison with a conventional single channel token passing approach using the same overall network transmission rate (i.e. the sum of the individual channel bit rates in the multichannel case). Furthermore, when the end-to-end propagation delay for an individual channel on the network becomes large, the multichannel token passing protocol is shown to exhibit an improved delay versus throughput performance over a multichannel protocol employing carrier sense multiple access with collision detection.     

Providing per-session deterministic quality of service guarantees in cross-path packet switch

Recently, a quasi-static routing scheme called path switching was proposed for large-scale packet switch systems. The path-switched Clos network is called a cross-path switch. Cross-path switch is capable of supporting multirate and multicast traffic. In this paper, we develop a general framework for it to handle multimedia traffic. We obtain upper bounds on the delay and backlog at the cross-path switch on a per-session basis, wherein no packet lost or delay bound violation is allowed. Our results show that these bounds much depend on the way of token assignment at the central stage. To understand such dependence, we quantify the effect of the token assignment on the switch performance. From these results, we design an effective token assignment scheme to achieve better performance guarantees in the switch. We show that cross-path switch with such token assignments always provides near-optimal performance guarantees to each data session.     

USB身份锁的强化识别

USB设备通过主机的识别之后，与主机之间建立起一条USB传输信道，这是设备实现功能的基础。USB身份锁是网络身份认证系统中常用的信息载体，相比较常规USB设备，身份锁具有更高的安全性要求。文章给出一个基于厂商认证协议的身份锁强化识别方案，在实现USB设备标准配置的基础上，通过增加设备和驱动之间的可信身份认证，加强设备的识别处理。     

An extended token bus protocol for embedded networks

The network environment considered in this paper exists in commercial and military products such as Autonomous Aircraft and Vehicles. In these products sensors and processors are utilized for control, diagnosis, repair and communication. We refer to such networks as embedded networks and present a bus protocol suitable for these networks. Two modes of operation have been defined for the proposed protocol (IMAP). Normal mode is defined as that in which token passing is done in a random order and the token remains within a cluster of active stations. The other mode of operation is called the interrupt mode. In this mode, token bus operation is carried out and the token is passed through every station. Performance in terms of channel utilization and delay characteristics of IMAP is compared to the token bus and CSMA/CD performance. The performance models are developed by obtaining time-distance diagrams of token bus and IMAP. It is observed that IMAP has better performance characteristics than the conventional token bus and CSMA/CD.     

How to Effectively Use Multiple Channels in Wireless Mesh Networks

Operating on a frequency band occupying several nonoverlapping channels, IEEE 802.11 is now widely used in wireless mesh networks (WMNs). Many multichannel MAC protocols are proposed to improve the spatial reuse in the network under the assumption that the transmissions on nonoverlapping channels do not interfere with each other. Some joint routing and channel assignment algorithms are also designed to increase the network throughput based on the premise that we can switch between different channels freely. Although simulations show that great improvements on network throughput can be observed in both cases, two fundamental questions remain: 1) Can we really use multiple nonoverlapping channels freely in WMNs? 2) If we can, what will be the cost when we switch channels dynamically and frequently? In this paper, by conducting extensive experiments on our testbed, we attempt to answer these questions. We find that in spite of interference between both overlapping and nonoverlapping channels, we can still use multiple channels in mesh networks under certain conditions but with care. We also show that the channel switching cost is actually very significant in WMNs. We recommend not to switch the channels too frequently when designing the channel assignment algorithms, and those channel assignment algorithms selecting one channel for each packet are not really beneficial.     

Miniaturized frequency‐agile bandpass filter integrated single‐pole double‐throw switch

This article presents a miniaturized frequency‐agile bandpass filter (BPF) integrated single pole double throw (SPDT) switch using common LC resonator. The BPF‐integrated on‐sate channel is constituted by the capacitively coupled LC resonators with loaded varactor diodes and reverse‐biased p‐i‐n diodes. The off‐state channel with high suppression is built when the p‐i‐n diodes loaded LC resonators is forward‐biased. As an example, a frequency‐agile BPF‐integrated SPDT switch with constant 3‐dB fractional bandwidth of 18.4% is designed. Its fabricated circuit area including bias circuit but excluding feeding lines is 0.105 λ_g × 0.079 λ_g. Measured results show that its 3 dB operating frequency bandwidth covers from 0.499 to 1.077 GHz with in‐band insertion loss varying from 4.15 to 3.15 dB. Off‐state suppression better than 37.8 dB, port‐to‐port isolation better than 51.1 dB, and good return loss can be also observed.     

基于IEEE802．15．4a的无线测控网络协议

为满足工业现场测控任务对网络通信实时性的要求,提出一种基于IEEE80215．4a的无线测控网络协议,其中的令牌控制子层采用令牌机制管理各站点对无线信道的访问,克服了CSMA／CA机制无序竞争的缺陷,保证数据传输的时间确定性,介绍协议栈模型、逻辑令牌环动态建立过程以及令牌故障的自恢复机制,并在硬件平台NanoNET上加以实现。实验结果表明,该协议能够在强电磁干扰环境中稳定运行,具备实时特性。