基于OTDR的EPON在线监测和保护系统的研究
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摘要
近年来，随着智能电网、远程医疗和云计算等技术的发展，“光进铜退”已经成为一个必然趋势。无源光网络(PON)，特别是以太无源光网络(EPON)，以其带宽高、抗干扰能力强、可靠性高、成本低等特点，已经成为各大运营商解决“最后一公里”问题的最佳选择之一。
根据调查数据显示，光网络中大部分故障都发生在光链路上，而这些故障会影响用户的网络体验，甚至造成经济损失。随着用户维权意识的提高和相关行业标准的完善，运营商会为EPON网络故障付出越来越高的代价。所以，有效地对链路进行监测和故障定位，以及为链路配备合理的备份保护方案，以提高网络的可靠性和减小维护成本，就成为了业界所关注的一个重要课题。
目前，关于基于OTDR的EPON在线监测系统的研究成果都没有同时解决曲线混叠、测试信号衰减和暗纤监测的问题。因此，本文通过改进现有的研究成果，先提出了一种结合OTDR的EPON在线监测和保护系统，并在GE Smallworld PNI的基础上开发了配套的GIS管理系统，从而形成了一套可以进行快速链路故障定位的在线监测和保护系统。该系统将在线监测与备份保护相结合，同时避免了曲线混叠、测试信号衰减和暗纤监测的问题，并采用了单位成本较低的只对馈线保护的方案。然而实验结果证明，系统虽然可以实现在线监测，但由于将OTDR作为故障侦测的手段，检测链路的时间较长，所以无法实时地发现故障，实现快速的保护切换。
针对这一问题，本文提出了一套与网管系统相结合的EPON在线监测和保护系统。该系统通过EPON网管程序进行链路监测，利用SNMP协议传递告警信息，从而实现对链路故障的实时侦测。实验证明系统在继承前一个系统优点的基础上，可以实现快速的保护切换，从而解决了前一个系统中保护切换时间较长的缺点。
最后，本文对研究过程中开发的GIS管理系统做了详细的说明，主要包括故障标记模块、事件管理模块和OTDR测试模块所实现的功能、算法和工作流程，并通过软件测试证明该管理系统可以响应网管告警，从而实现保护切换、故障告警等功能。
With the development of smart grid, remote medical service and cloud computation, copper cables will finally be replaced by optical fibers. Nowadays, Passive Optical Network (PON), especially Ethernet Passive Optical Network (EPON), becomes more and more popular due to its high bandwidth, high reliability and low cost, which make it one of the most suitable technologies for service providers to solve the“last mile”problem.
However, Statistics show that most of the faults in optical networks are link failures, which will disturb network using and even cause financial loss. With the improvement of users’rights awareness and relative specifications, service providers will pay much more for the network failure. So, it is important to find a way to efficiently monitor links and localize faults, and to improve network reliability with certain protection strategies.
Nowadays, researches about monitoring system based on OTDR for PON cannot solve problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. As a result, by improving existed designs, the author has proposed a novel online monitoring and protection system based on OTDR for EPON. With the GIS management system based on redeveloped GE Smallworld PNI, it becomes a complete monitoring system which can rapidly localize fault points on fibers. The system implements both online monitoring and backup protection strategy, and it can solve the problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. The experiments have proved that the system can realize online monitoring, but cannot achieve fast protection switch due to design defects.
As a result, the author has then proposed an online monitoring and protection system with Network Management System for EPON. The system works with EPON NMS, and it can realize real-time fault detection via SNMP protocol. Experiment result shows that the system can achieve fast protection switch. Finally, it has solved the previous problem of slow switch time, while kept the advantages of the previous system.
At last, the authors has explained the design and realization of the GIS management system, mainly including the design purpose, relative algorithm, flow diagram. Test results show that the system can respond to NMS alarm, and achieve protection switch and fault alert.
根据调查数据显示，光网络中大部分故障都发生在光链路上，而这些故障会影响用户的网络体验，甚至造成经济损失。随着用户维权意识的提高和相关行业标准的完善，运营商会为EPON网络故障付出越来越高的代价。所以，有效地对链路进行监测和故障定位，以及为链路配备合理的备份保护方案，以提高网络的可靠性和减小维护成本，就成为了业界所关注的一个重要课题。
目前，关于基于OTDR的EPON在线监测系统的研究成果都没有同时解决曲线混叠、测试信号衰减和暗纤监测的问题。因此，本文通过改进现有的研究成果，先提出了一种结合OTDR的EPON在线监测和保护系统，并在GE Smallworld PNI的基础上开发了配套的GIS管理系统，从而形成了一套可以进行快速链路故障定位的在线监测和保护系统。该系统将在线监测与备份保护相结合，同时避免了曲线混叠、测试信号衰减和暗纤监测的问题，并采用了单位成本较低的只对馈线保护的方案。然而实验结果证明，系统虽然可以实现在线监测，但由于将OTDR作为故障侦测的手段，检测链路的时间较长，所以无法实时地发现故障，实现快速的保护切换。
针对这一问题，本文提出了一套与网管系统相结合的EPON在线监测和保护系统。该系统通过EPON网管程序进行链路监测，利用SNMP协议传递告警信息，从而实现对链路故障的实时侦测。实验证明系统在继承前一个系统优点的基础上，可以实现快速的保护切换，从而解决了前一个系统中保护切换时间较长的缺点。
最后，本文对研究过程中开发的GIS管理系统做了详细的说明，主要包括故障标记模块、事件管理模块和OTDR测试模块所实现的功能、算法和工作流程，并通过软件测试证明该管理系统可以响应网管告警，从而实现保护切换、故障告警等功能。
With the development of smart grid, remote medical service and cloud computation, copper cables will finally be replaced by optical fibers. Nowadays, Passive Optical Network (PON), especially Ethernet Passive Optical Network (EPON), becomes more and more popular due to its high bandwidth, high reliability and low cost, which make it one of the most suitable technologies for service providers to solve the“last mile”problem.
However, Statistics show that most of the faults in optical networks are link failures, which will disturb network using and even cause financial loss. With the improvement of users’rights awareness and relative specifications, service providers will pay much more for the network failure. So, it is important to find a way to efficiently monitor links and localize faults, and to improve network reliability with certain protection strategies.
Nowadays, researches about monitoring system based on OTDR for PON cannot solve problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. As a result, by improving existed designs, the author has proposed a novel online monitoring and protection system based on OTDR for EPON. With the GIS management system based on redeveloped GE Smallworld PNI, it becomes a complete monitoring system which can rapidly localize fault points on fibers. The system implements both online monitoring and backup protection strategy, and it can solve the problems such as overlay of otdr traces, attenuation of monitoring signals and dark fiber monitoring at the same time. The experiments have proved that the system can realize online monitoring, but cannot achieve fast protection switch due to design defects.
As a result, the author has then proposed an online monitoring and protection system with Network Management System for EPON. The system works with EPON NMS, and it can realize real-time fault detection via SNMP protocol. Experiment result shows that the system can achieve fast protection switch. Finally, it has solved the previous problem of slow switch time, while kept the advantages of the previous system.
At last, the authors has explained the design and realization of the GIS management system, mainly including the design purpose, relative algorithm, flow diagram. Test results show that the system can respond to NMS alarm, and achieve protection switch and fault alert.
引文
[1]江伟，海底光缆的故障现象及修理程序[J]光纤通信，2003，(9)：32-36
[2]Ab-RahmaaaM S，NgBC，SafnalMHG，et al TheOverview-ofFiber FaultLocalization Technology in TDM Network[C]，International Conference onElectronic Design，2008：1-8
[3]康晨，OTDR远程光缆集中监测系统研究[学位论文]，北京，北京邮电大学，2007
[4]徐辉，李风堂，刘媛媛，EPON中的接入控制技术[J]现代电子技术，2003，26(24)：50-53
[5]石顺祥，孙艳玲，马琳等，光纤技术与作用[M]，武汉：华中科技大学出版社，2009
[6]张傲，程淑玲等，三网融合下的FFTx网络[M]，北京：人民邮电出版社，2011
[7]Rad M M，Fouli K，FmhNlah H A，et al，Passive optical network monitoring：challenges and requirements[J]，IEEE Communications magazine，2011，49(2)：s45．s52
[8]马正先，熊建文，OTDR在光纤测量中的应用[Jl激光杂志，1999，20(2)：1-7
[9]李腾浅谈OTDR测试曲线分析[LIll 2011，(4)：31-32
[10]田国栋，基于OTDR技术的光纤测试方法探讨[LIll 2009，32(19)：99-101
[11]熊森，将分布式光纤传感技术融入EPON的研究[学位论文]，成部，电子科技大学，2009
[12]曹磊，光纤测试与光时域反射(OTDR)技术在宽带网建设中的应用[C]，信息通信网技术业务发展研讨会论文集，2007
[13]杨慧梅，林如俭．EPON网络管理系统中链路监测功能的研究[J]微计算机信息，2005，1：55-46
[14]Byung-Tak L，Mun-Seob L，Rem~e Fault Detection Method for Time-SlotViolated Terminal Using Periodic Probing Signal in TDM-PON[J]，Journal ofLightwave Technology,2009，27(16)：3498-3508
[15]Ab-Rahmma M S，Ng B C，Premadi A，et al Transmission surveillance madself-restoration against fiber fault for time division multiplexing using passiveoptical network[J]，Communications，2009，3(12)：1896-1906
[16]Caviglia E Di Biase Vc，OPTICAL MAINTENANCE 1N PONs[C]，24thEuropean Conference on Optical Communication，1998，1：621-625
[17]Gagnon N，Giraxad A，Leblanc M，Considerations and Recommendations forIn-Service Out-of-Broad Testing on Live FTTH Networks[C]．OFC／NFOEC．2006
[18]陈希，光纤和光缆的监测与管理系统[LIll电力系统通信，2002，23(5)：11-13
[19]Ng B，Ab-Rahmma M S，Premadi A，et al Portable Network Monitoring System forPassive O’ptical Network(PON)[C]，International Conference on ComputerTechnology and Development．2009．2：176-180
[20]Dong-Min Seol，Eui-Suk Jung，Sang-Soo Lee，Cost-effective protection inlong-reach hybrid PON[C]，European Conference and Exhibition on OpticalCommunication，2010：1-3[211解东宏，陈光静，杨剑等，光网络物理层监测倒换系统的研究与实现[J]光通信技术，2008，32(10)：8-10
[22]Yuksel K，Moeyaert V Wuilpart M，et al Optical layer monitoring in PassiveOptical Networks(PONs)-A review[C]，10th Intemational Conference onTransparent Optical Networks，2008，1：92 98
[23]Ehrhardt A，Foisel H-M，Escher E et al Monitoring ofthe Transparent FibreInfrastructure for FTTx Networks：An Operator’S View[C]，12th IntemationalConference on Transparent Optical Networks，2010：1-5
[24]Honda N，Iida D，Izumita H，et al In-Service Line Monitoring System in PONsUsing 1650-nin Brillouin OTDR mad Fibers With Individually Assigned BFSs[J]，Lightwave Technolog~2009，27(20)：4575 4582[251Ng Boon Chuan，Premadi A，Ab-Rahmam M S，et al Physical Layer Monitoring in8-branched PON-based i-FTTH[C]，Intemational Conference on Photonics，2010：1．5
[26]范丽，喻杰奎，胡强高等，新型PON光缆监测系统的研制与开发[c]，全国第14次光纤通信暨第15届集成光学学术会议，2009
[27]Costa L，Laza*o J A，Polo V，et al，Viability of In-Service，Low-Cost andSpatially Unmnbignous OTDR Monitoring in TDM--and WDM--PON AccessNetworks[C]，International Conference on Transparent Optical Networks(ICTON)，2009：1-4
[28]LEE Jong Hoon，MOON Jung-Hyung，CHOI Ki-Man，et al Seamless Mmntenanceand Protection Scheme for Next-Generation Access Networks[J]，IEEE PhotonicsTechnology Letters，2009，21(12)：799-801
[29]Jiajia C，Wosinska L，Machuca C，et al，Cost VS reliability performance study offiber access network architectures[Jl，IEEE Communications Magazine，2010，48r2、：56-65
[30]上海电信，上海城市光网建设方案介绍，2009 9
[31]方亮，EPON系统网络管理功能的研究[学位论文]，上海，上海大学，2004
[32]华为，Huawei iManagerU2000 V100R001系统介N(Vl O)，2009 6
[33]李研，基于SNMP的EPON网元管理系统的研究与开发[学位论文]，武汉，华中科技大学，2003
[34]李雄伟，基于SNMP的网络故障监测技术研究[学位论文]，西安，长安大学，2008
[35]苏波，陈芳，GE Smallworld：一个面向企业的GIS平台[C]，中国地理信息系统协会第三次代表大会暨第七次年会，2003
[36]吴信才，空间数据库第一章[M]，北京：科学出版社，2009：1-23
[37]王民量，MarkH，ColinL，Smallworld在电信行业物理网络资源管理中的应用[C]，中国地理信息系统第八届年会，2004
[38]General Electric Company,Smallworld Core Spain Technology DocumentationMain，2006
[39]Telcordia,Optical Time Domain Reflectometer Data Format SR-4731，2011
[40]General Electric Company,Smallworld Physical Network Inventory 4 1 Class DOCtumentation，2007
[2]Ab-RahmaaaM S，NgBC，SafnalMHG，et al TheOverview-ofFiber FaultLocalization Technology in TDM Network[C]，International Conference onElectronic Design，2008：1-8
[3]康晨，OTDR远程光缆集中监测系统研究[学位论文]，北京，北京邮电大学，2007
[4]徐辉，李风堂，刘媛媛，EPON中的接入控制技术[J]现代电子技术，2003，26(24)：50-53
[5]石顺祥，孙艳玲，马琳等，光纤技术与作用[M]，武汉：华中科技大学出版社，2009
[6]张傲，程淑玲等，三网融合下的FFTx网络[M]，北京：人民邮电出版社，2011
[7]Rad M M，Fouli K，FmhNlah H A，et al，Passive optical network monitoring：challenges and requirements[J]，IEEE Communications magazine，2011，49(2)：s45．s52
[8]马正先，熊建文，OTDR在光纤测量中的应用[Jl激光杂志，1999，20(2)：1-7
[9]李腾浅谈OTDR测试曲线分析[LIll 2011，(4)：31-32
[10]田国栋，基于OTDR技术的光纤测试方法探讨[LIll 2009，32(19)：99-101
[11]熊森，将分布式光纤传感技术融入EPON的研究[学位论文]，成部，电子科技大学，2009
[12]曹磊，光纤测试与光时域反射(OTDR)技术在宽带网建设中的应用[C]，信息通信网技术业务发展研讨会论文集，2007
[13]杨慧梅，林如俭．EPON网络管理系统中链路监测功能的研究[J]微计算机信息，2005，1：55-46
[14]Byung-Tak L，Mun-Seob L，Rem~e Fault Detection Method for Time-SlotViolated Terminal Using Periodic Probing Signal in TDM-PON[J]，Journal ofLightwave Technology,2009，27(16)：3498-3508
[15]Ab-Rahmma M S，Ng B C，Premadi A，et al Transmission surveillance madself-restoration against fiber fault for time division multiplexing using passiveoptical network[J]，Communications，2009，3(12)：1896-1906
[16]Caviglia E Di Biase Vc，OPTICAL MAINTENANCE 1N PONs[C]，24thEuropean Conference on Optical Communication，1998，1：621-625
[17]Gagnon N，Giraxad A，Leblanc M，Considerations and Recommendations forIn-Service Out-of-Broad Testing on Live FTTH Networks[C]．OFC／NFOEC．2006
[18]陈希，光纤和光缆的监测与管理系统[LIll电力系统通信，2002，23(5)：11-13
[19]Ng B，Ab-Rahmma M S，Premadi A，et al Portable Network Monitoring System forPassive O’ptical Network(PON)[C]，International Conference on ComputerTechnology and Development．2009．2：176-180
[20]Dong-Min Seol，Eui-Suk Jung，Sang-Soo Lee，Cost-effective protection inlong-reach hybrid PON[C]，European Conference and Exhibition on OpticalCommunication，2010：1-3[211解东宏，陈光静，杨剑等，光网络物理层监测倒换系统的研究与实现[J]光通信技术，2008，32(10)：8-10
[22]Yuksel K，Moeyaert V Wuilpart M，et al Optical layer monitoring in PassiveOptical Networks(PONs)-A review[C]，10th Intemational Conference onTransparent Optical Networks，2008，1：92 98
[23]Ehrhardt A，Foisel H-M，Escher E et al Monitoring ofthe Transparent FibreInfrastructure for FTTx Networks：An Operator’S View[C]，12th IntemationalConference on Transparent Optical Networks，2010：1-5
[24]Honda N，Iida D，Izumita H，et al In-Service Line Monitoring System in PONsUsing 1650-nin Brillouin OTDR mad Fibers With Individually Assigned BFSs[J]，Lightwave Technolog~2009，27(20)：4575 4582[251Ng Boon Chuan，Premadi A，Ab-Rahmam M S，et al Physical Layer Monitoring in8-branched PON-based i-FTTH[C]，Intemational Conference on Photonics，2010：1．5
[26]范丽，喻杰奎，胡强高等，新型PON光缆监测系统的研制与开发[c]，全国第14次光纤通信暨第15届集成光学学术会议，2009
[27]Costa L，Laza*o J A，Polo V，et al，Viability of In-Service，Low-Cost andSpatially Unmnbignous OTDR Monitoring in TDM--and WDM--PON AccessNetworks[C]，International Conference on Transparent Optical Networks(ICTON)，2009：1-4
[28]LEE Jong Hoon，MOON Jung-Hyung，CHOI Ki-Man，et al Seamless Mmntenanceand Protection Scheme for Next-Generation Access Networks[J]，IEEE PhotonicsTechnology Letters，2009，21(12)：799-801
[29]Jiajia C，Wosinska L，Machuca C，et al，Cost VS reliability performance study offiber access network architectures[Jl，IEEE Communications Magazine，2010，48r2、：56-65
[30]上海电信，上海城市光网建设方案介绍，2009 9
[31]方亮，EPON系统网络管理功能的研究[学位论文]，上海，上海大学，2004
[32]华为，Huawei iManagerU2000 V100R001系统介N(Vl O)，2009 6
[33]李研，基于SNMP的EPON网元管理系统的研究与开发[学位论文]，武汉，华中科技大学，2003
[34]李雄伟，基于SNMP的网络故障监测技术研究[学位论文]，西安，长安大学，2008
[35]苏波，陈芳，GE Smallworld：一个面向企业的GIS平台[C]，中国地理信息系统协会第三次代表大会暨第七次年会，2003
[36]吴信才，空间数据库第一章[M]，北京：科学出版社，2009：1-23
[37]王民量，MarkH，ColinL，Smallworld在电信行业物理网络资源管理中的应用[C]，中国地理信息系统第八届年会，2004
[38]General Electric Company,Smallworld Core Spain Technology DocumentationMain，2006
[39]Telcordia,Optical Time Domain Reflectometer Data Format SR-4731，2011
[40]General Electric Company,Smallworld Physical Network Inventory 4 1 Class DOCtumentation，2007