用于Mesh光网络快速保护恢复的GMPLS信令机制的扩展

分析了Mesh光网络保护机制和恢复机制,并对GMPLS信令机制进行了扩展,给出了扩展后实现保护恢复的协议格式和信令流程,最后依据实验数据给出扩展的GMPLS信令机制的保护、恢复时间的仿真结果.     

Architectures for ATM network survivability and their fielddeployment

Future networks must offer extremely high levels of reliability because information has become critical to the continued well-being of society. This article shows the approaches to the survivable ATM network. The reliability requirements of future networks are discussed first. Development results of three typical restoration architectures (automatic protection switch (APS), self-healing network (SHN), and failure-resistant virtual path (FRVP)) for ATM networks are then shown. Next, we describe current progress in standardization activities. They also discuss open issues that must be resolved in future studies     

FTTH与CATV--日本光接入系统业界的动向

1 前言日本的光接入系统业界,从2001启动的光纤引入个人家庭的FTTH合同用户,到2004年12月已达到100万。2004年与以往比较,一年间增加了两倍多。目前,在日本的接入系统中,代替过去曾经起过宽带牵头作用的ADSL,现今以FTTH为中心的FTTH 光网的跃进非常显著。其中,FTTH的发展现状究竟到了什么程度?CATV的前景与对策如何?成了业界的重要视点。     

Sprint long distance network survivability: today and tomorrow

The high reliability exhibited by the Sprint long distance network is the result of many interrelated factors. The network utilizes robust architectures, systems, and equipment to provide a reliable transport infrastructure. Redundant equipment, conservative synchronization, protected power, and other factors combine to form a dependable foundation. New architectures and systems are under development to meet the changing demands of customers. This article summarizes Sprint's current network reliability, and emerging demands and technology, and presents possible directions for the future Sprint network. Sprint selected the SONET four-fiber bidirectional line switched ring (4F BLSR) architecture for the vast majority of its transport network architecture. A 4F BLSR architecture requires four fibers, or four optical wavelengths of wave division multiplexing (WDM), to accommodate a work and protect path in each direction around a ring of network elements or add-drop multiplexers (ADMs)     

Evolutionary architecture for an all-services ATM access network

This paper presents a flexible concept for a broadband subscriber access network which minimizes investment costs by predominantly using the existing network infrastructure. The target network may consist of either a coaxial tree-and-branch structure or symmetrical copper pairs to the subscriber, and is connected to the central head station with the aid of optical feeder lines which can be implemented or enhanced by a passive optical network (PON). In the event of an increase in bit rate requirements, the coaxial network can be expanded by dividing it into smaller, optically fed subnetworks or by supplementing it with optical overlay systems. Flexibility, expandability and low costs are achieved through the standard ATM format implemented for the signals of all interactive services down to the network termination units on the subscriber side. Those signals are transmitted in the coaxial network in frequency bands above the CATV band in accordance with a multiple of the CATV channel width to ensure that the modulation and demodulation is implemented in a cost-efficient manner while providing ‘bit rate on demand’ for a suitably high number of subscribers. Separation of the network termination unit from the customer premises equipment enables a flexible, cost-efficient subscriber configuration to be selected, existing domestic wiring to be used and several completely different subscriber terminals to be simultaneously connected.     

IP layer restoration and network planning based on virtual protection cycles

We describe a novel restoration strategy called virtual protection cycles (p-cycles, patents pending) for extremely fast restoration in IP networks. Originally conceived for use in WDM and Sonet transport networks, we outline the adaption of the p-cycle concept to an IP environment. In an IP router-based network, p-cycles are implemented with virtual circuits techniques (such as an MPLS label switched path, or other means) to form closed logical loops that protect a number of IP links, or a node. In the event of failure, packets which would normally have been lost are encapsulated with a p-cycle IP address and reenter the routing table, which diverts them onto a protection cycle. They travel by normal forwarding or label switching along the p-cycle until they reach a node where the continuing route cost to the original destination is lower than that at the p-cycle entry node. Diverted packets are deencapsulated (dropped from the p-cycle) at that node and follow a normal (existing) route from there to their destination. Conventional routing protocols such as OSPF remain in place and operate as they do today, to develop a longer term global update to routing tables. Diversionary flows on the p-cycle inherently cease when the global routing update takes effect in response to the failed link or node. The p-cycle thus provides an immediate real-time detour, preventing packet loss, until conventional global routing reconvergence occurs. The aim of the paper is to explain the basic p-cycle concept and its adaptation to both link and node restoration in the IP transport layer, and to outline certain initial results on the problem of optimized design of p-cycle based IP networks.     

共享单车-网络架构及质量监测体系的研究

如今,很多上班族和学生将共享单车作为出行的首选工具。每一辆单车都配有一个智能锁,通过运营商的无线网络,连接到单车企业的系统平台。数以千万计的共享单车为市民出行带来了便利,也给通信网络的性能监控和运营带来了新的挑战。文章旨在通过对共享单车应用的系统架构、业务机制进行研究,对行业终端(智能锁)的通信行为进行分析,掌握共享单车的解锁、闭锁流程,提炼出业务流程中的网络行为模型,并建立针对应用的网络性能指标体系,最终利用自动化的大数据分析平台,开发出一套行之有效的业务监测系统。     

OHS: A Novel hybrid survivability approach for WDM mesh networks

In this paper, we investigate the problem of single-link failure for multiple levels of service in wavelenght-division-multiplying (WDM) mesh networks, and propose a novel on-line hybrid survivability (OHS) approach. OHS provides differentiated survivability strategies for dynamic connection requests with multiple levels of service. For the new arriving connection requests, OHS can instantly adjust the cost of the link according to the current state of the network, and calculate the primary path or backup path (if needed). Simulation results show OHS is able to obtain better performance (in terms of network resource utilization, blocking ratio) than the previous algorithms.     

Distributed restoration in an ATM test bed network

Network resilience is a crucial area of concern for telecommunications network operators who aim to provide high availability services supported by a broadband platform based on ATM technology. This paper describes the development of an ATM test bed network which incorporates resilience by executing distributed restoration in the event of failures. Since the work originated from collaborative research between BT Laboratories and Alcatel Telecom of Belgium, the paper highlights challenges faced in developing a restorable network, both by a network operator, and a switch manufacturer.     

FTTH中光纤光缆的发展

FTTH正在走入人们实用化的视野,国内外很多光缆生产厂商或研究所都提出了自己的构想,本文着重介绍了FTTH应用中的一些典型的光纤及光缆技术,对FTTH在我国的发展前景做了分析,并提出了自己在FTTH发展中的一些观点.     

The arrayed-waveguide grating-based single-hop WDM network: an architecture for efficient multicasting

Research on multicasting in single-hop wavelength-division-multiplexing (WDM) networks has so far focused on networks based on the passive star coupler (PSC), a broadcast device. It has been shown that multicasting performance is improved by partitioning multicast transmissions into multiple multicast copies. However, the channel bottleneck of the PSC, which does not allow for spatial wavelength reuse, restricts the multicast performance. We investigate multicasting in a single-hop WDM network that is based on an arrayed-waveguide grating (AWG), a wavelength routing device that allows for spatial wavelength reuse. In our network, optical multicasting is enabled by wavelength-insensitive splitters that are attached to the AWG output ports. Multicasts are partitioned among the splitters and each multicast copy is routed to a different splitter by sending it on a different wavelength. We demonstrate that the spatial wavelength reuse in our network significantly improves the throughput-delay performance for multicast traffic. By means of analysis and simulations, we also demonstrate that, for a typical mix of unicast and multicast traffic, the throughput-delay performance is dramatically increased by transmitting multicast packets concurrently with control information in the reservation medium access control protocol of our AWG-based network.     

Superresolution restoration of an image sequence: adaptivefiltering approach

This paper presents a new method based on adaptive filtering theory for superresolution restoration of continuous image sequences. The proposed methodology suggests least squares (LS) estimators which adapt in time, based on adaptive filters, least mean squares (LMS) or recursive least squares (RLS). The adaptation enables the treatment of linear space and time-variant blurring and arbitrary motion, both of them assumed known. The proposed new approach is shown to be of relatively low computational requirements. Simulations demonstrating the superresolution restoration algorithms are presented.     

Methods and models for computing survivability and fault-tolerance of a network

this paper presents methods for computing network survivability indexes under multiple external (adverse) effect which causes a network gradual structur al degradation. A multiple external effect (MEE) is a discrete flow of separate actions. Probabilistic models for MEE with difference strategies and ranges of actions are presented. In particular, if MEE is a flow of local (point) actions, each of which disables exactly one element of network and destroyed elements are excluded from ranges of following actions, then proposed indexes may be used for the evaluation of network fault-tolerance.     

无源光网络冗余保护及应用实现

PON网络相对于传统网络组网简单,无源传输,提供可观接入速率和多业务应用,得到了蓬勃发展。通过对PON网络组网结构以及业务特征的定性研究,分析了PON网络中不同保护方式对应的应用场景。并对在网络设计中考虑保护以及在组网各个节点进行冗余保护以及提升网络运行稳定性,提高用户体验感知的有效方法进行了总结。并对特殊应用下的PON网络结合和冗余保护实现进行分析总结。     

信令监测系统架构规范的演进

本文详细描述了信令监测系统架构的演进和优化,对新架构下的监测系统及其提供开放的接口、数据格式进行了详细的说明,并且对新架构下的信令监测系统在现网中的应用方式进行了分析.     

PriMa: a comprehensive approach to privacy protection in social network sites

With social networks (SNs) allowing their users to host large amounts of personal data on their platforms, privacy protection mechanisms are becoming increasingly important. The current privacy protection mechanisms offered by SNs mostly enforce access control policies based on users’ privacy settings. The task of setting privacy preferences may be tedious and confusing for the average user, who has hundreds of connections (e.g., acquaintances, colleagues, friends, etc.) and maintains an extensive profile on his main SN. Hence, users often end up with policies that do not sufficiently protect their personal information, thus facilitating potential privacy breaches and information misuse. In this paper, we propose PriMa (Privacy Manager), a privacy protection mechanism that supports semiautomated generation of access rules for users’ profile information, filling the gap between the privacy management needs of SN users and the existing SNs’ privacy protection mechanisms. PriMa access rules are generated using a multicriteria algorithm, so as to account for an extensive set of criteria to be considered when dealing with access control in SN sites. The resulting rules are simple yet powerful specifications, indicating the adequate level of protection for each user, and are dynamically adapted to the ever-changing requirements of the users’ preferences and SN configuration. We have implemented PriMa on a Drupal platform and as a third-party Facebook application. We have evaluated the performance of the PriMa application with respect to access rule generation.     

Bi-Fi: an embedded sensor/system architecture for REMOTE biological monitoring.

Wireless-enabled processor modules intended for communicating low-frequency phenomena (i.e., temperature, humidity, and ambient light) have been enabled to acquire and transmit multiple biological signals in real time, which has been achieved by using computationally efficient data acquisition, filtering, and compression algorithms, and interfacing the modules with biological interface hardware. The sensor modules can acquire and transmit raw biological signals at a rate of 32 kb/s, which is near the hardware limit of the modules. Furthermore, onboard signal processing enables one channel, sampled at a rate of 4000 samples/s at 12-bit resolution, to be compressed via adaptive differential-pulse-code modulation (ADPCM) and transmitted in real time. In addition, the sensors can be configured to filter and transmit individual time-referenced "spike" waveforms, or to transmit the spike height and width for alleviating network traffic and increasing battery life. The system is capable of acquiring eight channels of analog signals as well as data via an asynchronous serial connection. A back-end server archives the biological data received via networked gateway sensors, and hosts them to a client application that enables users to browse recorded data. The system also acquires, filters, and transmits oxygen saturation and pulse rate via a commercial-off-the-shelf interface board. The system architecture can be configured for performing real-time nonobtrusive biological monitoring of humans or rodents. This paper demonstrates that low-power, computational, and bandwidth-constrained wireless-enabled platforms can indeed be leveraged for wireless biosignal monitoring.