XML‐Based Network Management for IP Networks

XML‐based network management, which applies XML technologies to network management, has been proposed as an alternative to existing network management. The use of XML in network management offers many advantages. However, most existing network devices are already embedded with simple network management protocol (SNMP) agents and managed by SNMP managers. For integrated network management, we present the architectures of an XML‐based manager, an XML‐based agent, and an XML/SNMP gateway for legacy SNMP agents. We describe our experience of developing an XML‐based network management system (XNMS), XML‐based agent, and an XML/SNMP gateway. We also verify the effectiveness of our XML‐based agent and XML/SNMP gateway through performance tests. Our experience with developing XNMS and XML‐based agents can be used as a guideline for development of XML‐based management systems that fully take advantage of the strengths of XML technologies.     

Web Services‐based network management: approaches and the WSNET system

While the Simple Network Management Protocol (SNMP) is still the dominant protocol for managing network elements in IP‐based networks and the Internet, network managers are acknowledging its limitations with respect to configuration management, application development and decentralization of management tasks. Web Services (WS) have been recently proposed to alleviate these limitations, given their pertinence to both decentralized management paradigms (e.g., CORBA), and XML management systems which provide efficiency in configuration management operations. This paper reviews architectures for WS‐based network management, outlining their advantages and disadvantages. These architectures address management of both individual network elements and composite multi‐device networks. Moreover, the paper introduces the architecture of a prototype system for WS‐based network management, namely WSNET. Along with presentation of the WSNET system, we provide a set of experimental results reporting performance figures for the WSNET system, as well as for systems based on other WS architectures. These figures allow for a comparative evaluation of the various systems, and manifest the benefits of the WSNET implementation. An important conclusion from our work is that WS should be seen as an accompaniment to conventional SNMP management rather than a replacement. However, there are also cases (e.g., need for secure remote access) where WS serve as a core rather than auxiliary solution, given that conventional methods are not applicable. Copyright © 2006 John Wiley & Sons, Ltd.     

关于DSL分离器瞬态响应测试配置的建议

基于实际测试经验,对DSL分离器瞬态响应测试配置提出了一些实施建议。但目前DSL分离器瞬态响应测试还在不断发展,测试方法和测试配置仍不完善,有待进一步研究。     

UbiXML: programmable management of ubiquitous computing resources

XML technologies provide proven benefits for the configuration management of complex heterogeneous multi‐vendor networks. These benefits have been recently manifested in numerous research, industrial and standardization efforts, including the XMLNET architecture. In this paper we present UbiXML, a system for programmable management of ubiquitous computing resources. UbiXML extends the benefits of XML technologies in the broader class of ubiquitous computing environments, which are inherently complex distributed heterogeneous and multi‐vendor. In UbiXML management applications are structured as XML documents that incorporate programming constructs. Thus, UbiXML allows administrators to build sophisticated management applications with little or no programming effort. While UbiXML builds on several XMLNET concepts, it significantly augments XMLNET to handle management of sensors, perceptual components and actuating devices. Moreover, UbiXML is extensible towards additional ubiquitous computing elements. UbiXML has been exploited in implementing realistic management applications for a smart space. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of SNMP‐XML translator and gateway for XML‐based integrated network management

The research objective of our work is to develop a SNMP MIB to XML translation algorithm and to implement an SNMP‐XML gateway using this algorithm. The gateway is used to transfer management information between an XML‐based manager and SNMP‐based agents. SNMP is widely used for Internet management, but SNMP is insufficient to manage continuously expanding networks because of constraints in scalability and efficiency. XML–based network management architectures are newly proposed as alternatives to SNMP‐based network management, but the XML‐based Network Management System (XML‐based NMS) cannot directly manage legacy SNMP agents. We also implemented an automatic specification translator (SNMP MIB to XML Translator) and an SNMP‐XML gateway. Copyright © 2003 John Wiley &Sons, Ltd.     

Advanced DSL management

Today's digital subscriber line deployments are often conservatively engineered to function in a statistically worst case environment. Crosstalk is treated as unknown and uncontrollable random noise, even though it is manmade. Other impairments are often treated by simply adding margin to crosstalk. While this simplistic practice currently suffices, it often provisions unnecessarily low bit rates. This article shows methods that can increase these bit rates and decrease DSL failure rates. Data can be collected about individual telephone lines and cables from loop databases, by automated test equipment, or from DSL modems. This data may then be fed into an advanced DSL management system with a database of DSL loop and noise characteristics, and an analysis engine that tailors DSL deployments to the actual individual line characteristics, to increase provisioned DSL bitrates while simultaneously increasing reliability and lowering maintenance costs. The maximum service can be provisioned with high accuracy, eliminating many service activation failures. Automated maintenance routines can even isolate faults before a customer experiences them. Dynamic spectrum management (DSM) treats crosstalk as the manmade noise it is, and jointly optimizes DSL transmit spectra and signals to minimize crosstalk and maximize received signals, allowing substantially higher DSL speeds than current practice. This opens the door for new services, including symmetric enterprise services and full video service, with minimal physical plant upgrade.     

基于XML技术的WSN网关系统的设计与实现

为了完成Internet与WSN之间的互联,扩展WSN数据服务,提出一种基于XML技术的WSN网关系统的设计和实现方案。基于S3C2440低功耗嵌入式处理器设计并实现了具有以太网,USB等扩展接口的网关硬件平台。利用XML技术和XML-RPC技术,设计了＂用户配置,按需解析＂的网关中间件。利用Flash动态网页和Web Service服务提供实时动态数据表现。网关系统有效地将数据解析与应用表现分离,实现了＂一网关多用途＂的功能,大大地简化了网关系统的配置、部署,提高了网关系统的重复利用性。     

Optimal multiuser spectrum balancing for digital subscriber lines

Crosstalk is a major issue in modern digital subscriber line (DSL) systems such as ADSL and VDSL. Static spectrum management, which is the traditional way of ensuring spectral compatibility, employs spectral masks that can be overly conservative and lead to poor performance. This paper presents a centralized algorithm for optimal spectrum balancing in DSL. The algorithm uses the dual decomposition method to optimize spectra in an efficient and computationally tractable way. The algorithm shows significant performance gains over existing dynamics spectrum management (DSM) techniques, e.g., in one of the cases studied, the proposed centralized algorithm leads to a factor-of-four increase in data rate over the distributed DSM algorithm iterative waterfilling.     

XBGP‐MAN: an XML management architecture for BGP

Network and system management paradigms have recently evolved towards flexible and lightweight integration approaches. These approaches are based on the transparent information‐processing capabilities offered by both generous support for self‐describing data enabled by XML as well as from the large base of existing underlying tools. BGP is, from a configuration point of view, one of the most complex protocols of the Internet and as such a very good validation environment for new management frameworks. This paper describes the practical experience gathered from the design, implementation and deployment of a comprehensive XML‐based management architecture for the Border Router Gateway Protocol. Copyright © 2006 John Wiley & Sons, Ltd.     

XML-based configuration management for IP network devices

As the Internet continues to grow, the tasks of operations and management of IP networks and systems are becoming more difficult. Over the past few years, much effort has been given to improve the deficiencies of SNMP, but most have failed to be standardized. One critical deficiency of SNMP is in the area of configuration management. Recent work focuses on the use of XML technology for network and service management as an alternative or complementary approach to SNMP. This article presents the IETF's latest effort, Netconf, which is viewed by many as a promising revolutionary solution for configuration management. To validate this new effort, we present the design and implementation of an XML-based configuration management system based on Netconf. We also discuss our experience with XCMS and make some suggestions for improving the current Netconf protocol.     

概率XML数据模型的综述

随着XML成为网络信息表示和交换的标准以及不确定数据的广泛存在,概率XML数据库管理技术成为了当今研究的热点,研究者根据概率数据的类型和解决实际问题的需要提出了多种概率XML数据模型。首先介绍了概率XML数据管理技术的概念,特点和挑战;其次综述了概率XML数据和概率XML数据模型,各种模型的核心思想都来自于可能世界模型,通过选择孩子节点以及删除节点可得到一个可能世界的实例,而且所有实例的概率之和为1;最后介绍了不同模型之间的转换关系。为概率XML数据库的查询、规范化理论奠定了基础。     

DSL spectrum management standard

Different digital subscriber lines transmitting on loops in the same telephone cable generate crosstalk into each other. Two different DSLs are spectrally compatible if they can both use the same cable with low probability of significant degradation from crosstalk. Spectrum management is the process of ensuring spectral compatibility while optimizing the loop plant. Spectrum management requires knowledge of cable plant characteristics extending into higher frequency spectra (/spl sim/1 MHz), the different DSL types, and how to compute the impact of crosstalk. Also, definitions of the level of crosstalk from one DSL type that significantly degrades another DSL type is needed, which can only reach broad acceptance through industry-wide agreements. In the United States, DSL Access Standards Committee T1E1.4 has created a technical definition of spectral compatibility, the Spectrum Management Standard T1.417-2001. The details of DSL spectral compatibility and compliance with the standard are presented, as well as a history of the standard and some possibilities for the future.     

A frequency-domain approach to crosstalk identification in xDSLsystems

Crosstalk between multiple services transmitting through the same telephone cable is the primary limitation to digital subscriber line services. From a spectrum management point of view, it is important to have an accurate map of all the services that generate crosstalk into a given pair. If crosstalk is measured via modem-based methods, i.e., while a digital subscriber line (DSL) system is running, what is measured is the crosstalk in the bandwidth of the considered DSL system. For this reason, DSL services running on adjacent pairs may not be detected if their bandwidth is not significantly overlapping with the bandwidth of the disturbed system. This is a major drawback of modem-based system identification techniques since, from a spectrum management point of view, it is important to be able to identify all crosstalkers. We address the important problem of crosstalk identification when the pair under test does not bear DSL services, i.e., via a non-modem-based approach. Crosstalk sources are identified in the frequency domain by finding the maximum correlation with a “basis set” of representative measured crosstalk couplings. The effectiveness of the proposed technique is also verified on the basis of real crosstalk measurements performed on actual cables. Finally, new techniques based on multiple regression and best basis selection are also discussed     

ADSL宽带测试技术

介绍国内外数字用户线DSL业务现状、发展趋势、宽带测试需求分忻以及ADSL宽带测试技术，测试项目、组网技术等。     

ERP系统在人力资源管理中的应用探究

信息化时代要求企业人力资源管理也实现信息化。笔者结合ERP系统的优势,运用XML技术,开发出一种新型人力资源管理系统,在实际应用中也取得良好效果。本文首先介绍ERP发展历程和工作原理,然后对XML技术结合ERP系统开发出的人力资源管理系统进行简要介绍,并分析其在人力资源管理中的应用,希望能提高人力资源管理的信息化水平。     

Dynamic spectrum management for next-generation DSL systems

The performance of DSL systems is severely constrained by crosstalk due to the electromagnetic coupling among the multiple twisted pairs making up a phone cable. In order to reduce performance loss arising from crosstalk, DSL systems are currently designed under the assumption of worst-case crosstalk scenarios leading to overly conservative DSL deployments. This article presents a new paradigm for DSL system design, which takes into account the multi-user aspects of the DSL transmission environment. Dynamic spectrum management (DSM) departs from the current design philosophy by enabling transceivers to autonomously and dynamically optimize their communication settings with respect to both the channel and the transmissions of neighboring systems. Along with this distributed optimization, when an additional degree of coordination becomes available for future DSL deployment, DSM will allow even greater improvement in DSL performance. Implementations are readily applicable without causing any performance degradation to the existing DSLs under static spectrum management. After providing an overview of the DSM concept, this article reviews two practical DSM methods: iterative water-filling, an autonomous distributed power control method enabling great improvement in performance, which can be implemented through software options in some existing ADSL and VDSL systems; and vectored-DMT, a coordinated transmission/reception technique achieving crosstalk-free communication for DSL systems, which brings within reach the dream of providing universal Internet access at speeds close to 100 Mb/s to 500 m on 1-2 lines and beyond 1 km on 2-4 lines. DSM-capable DSL thus enables the broadband age.     

Iterative Power Pricing for Distributed Spectrum Coordination in DSL

In this letter we propose a novel distributed technique for dynamic spectrum management of DSL lines. The proposed method generalizes several known techniques, by imposing pricing for use of spectrum. We propose a simple mechanism that allows each line to choose an appropriate pricing function independently of the other lines. Finally, by incorporating a total power constraint, the algorithm is capable of self-correcting an overly ambitious pricing function. We also provide simulated examples based on measured DSL lines.     

XML技术在空间数据管理中的应用

空间数据库是地理信息系统的核心.针对目前地理信息系统在空间数据管理中出现的问题,提出了新的方法—结合XML与关系型数据库各自的技术优势,将XML技术应用于空间对象的描述以及存储.