光通信技術外文翻譯

1、外文文獻閱讀及翻譯譯文及原稿譯文題目 以太網(wǎng)無源光網(wǎng)絡 原稿題目 Passive optical network based on Ethernet 姓 名 吳騰 學 號 31202130 班 級 通信1204 以太網(wǎng)無源光網(wǎng)絡 格倫·克雷默 北京郵電大學出版社 2007 以太網(wǎng)無源光網(wǎng)絡（Ethernet Passive Optical Network ， EPON） 是一種新型的光纖接入網(wǎng)技術，它采用點到多點結(jié)構、無源光纖傳輸，在以太網(wǎng)之上提供多種業(yè)務。它在物理層采用了PON技術，在鏈路層使用以太網(wǎng)協(xié)議，利用PON的拓撲結(jié)構實現(xiàn)了以太網(wǎng)的接入。因此，它綜合了PON技術和以太網(wǎng)技術

2、的優(yōu)點：低成本；高帶寬；擴展性強，靈活快速的服務重組；與現(xiàn)有以太網(wǎng)的兼容性；方便的管理等等。由于EPON的眾多優(yōu)點，它越來越受到人們的青睞，即將成為寬帶接入網(wǎng)一種最有效的通信方法。為了保證EPON網(wǎng)絡能夠穩(wěn)定、高效、準確的運行，為EPON提供一個有效的網(wǎng)絡管理系統(tǒng)顯得尤為重要。 在網(wǎng)絡管理領域，隨著基于TCP/IP體系的網(wǎng)絡管理技術的不斷發(fā)展，SNMP已經(jīng)成為事實上的標準。基于SNMP的EPON網(wǎng)絡管理系統(tǒng)是指采用SNMP管理協(xié)議框架，對EPON網(wǎng)絡實體的資源實現(xiàn)有效管理的系統(tǒng)。 SNMP的介紹SNMP（簡單網(wǎng)絡管理協(xié)議）是一種基于TCP/IP的網(wǎng)絡管理協(xié)議，它使用UDP作為傳輸層協(xié)議，能管理

3、支持代理進程的網(wǎng)絡設備。SNMP主要包括SMI（管理信息結(jié)構）、MIB（管理信息庫）和SNMP協(xié)議幾部分。SMI給出了管理對象定義的一般框架。MIB是設備所維護的全部被管理對象的結(jié)構集合。SNMP協(xié)議包括SNMP操作、SNMP信息的格式以及如何在應用程序和設備間交換消息。 SNMP采用代理/管理站模型進行網(wǎng)絡管理。SNMP有5種消息類型，分別為Get-Request、Get-Response、Get-Next-Request、Set-Request和Trap。代理和管理站之間通過這幾種消息報文進行相互通信，以獲取網(wǎng)絡設備的各種信息，從而控制網(wǎng)絡設備的正常運行。EPON網(wǎng)管系統(tǒng)結(jié)構EPON系統(tǒng)的

4、管理對象為1個OLT（光線路終端）和32個ONU（光網(wǎng)絡單元）?；赟NMP的EPON網(wǎng)管系統(tǒng)結(jié)構如圖2所示。EMS網(wǎng)管系統(tǒng)安裝在工作站，與OLT設備之間通過帶外網(wǎng)管接口（F接口）相連。EMS網(wǎng)管系統(tǒng)和OLT、ONU設備之間采用SNMP協(xié)議進行通信，實現(xiàn)在EMS中對OLT、ONU的統(tǒng)一管理。通信的方式有2種：（1）輪詢。管理站每隔一段時間對所有OLT和ONU代理站的MIB進行主動查詢，各代理站返回被查詢的結(jié)點值。（2）告警（trap）。當某些指定事件發(fā)生時，代理進程向管理站發(fā)送trap報文。管理站接收、顯示告警事件，并做相應處理。 同時OLT設備和ONU設備具備本地Console接口，可以實現(xiàn)

5、本地操作管理維護。EPON網(wǎng)管系統(tǒng)的設計 EPON網(wǎng)管系統(tǒng)按照網(wǎng)管功能分為四大模塊：配置管理、性能管理、故障管理和安全管理。1. 配置管理 配置管理主要是組織EPON網(wǎng)內(nèi)運轉(zhuǎn)所需要的資源和數(shù)據(jù)，構造和維護網(wǎng)絡系統(tǒng)的配置，識別各網(wǎng)元，保證網(wǎng)元的基本配置，監(jiān)控當前配置和按照具體情況改變配置，設置系統(tǒng)參數(shù)，收集并存儲各參數(shù)，報告與基本配置值的偏差，啟動和關閉資源等。 EPON配置管理包括系統(tǒng)初次啟動時的配置管理和系統(tǒng)正常運行時的配置管理。 啟動時，針對EPON網(wǎng)絡，可自動或手動生成OLT、ONU設備拓撲圖，顯示當前網(wǎng)絡中各OLT、ONU設備的狀態(tài)。在網(wǎng)絡拓撲圖生成后，SNMP 管理進程采用輪詢的方式

6、定期查詢SNMP 代理進程，收集設備信息用于更新數(shù)據(jù)庫，以實現(xiàn)配置信息的實時性。系統(tǒng)正常運行后，網(wǎng)管可根據(jù)需要隨時手動設置其各項配置參數(shù)。如可以設置各OLT、ONU代理的標識信息和系統(tǒng)信息，啟用、禁用某個端口，配置各端口的工作狀態(tài)，配置網(wǎng)橋的工作參數(shù)，配置VLAN，重啟設備等。還提供基于用戶的動態(tài)帶寬管理。2. 性能管理 性能管理功能對EPON網(wǎng)絡性能進行監(jiān)視、檢測，采集相關性能統(tǒng)計數(shù)據(jù)，進行分析、診斷，從而為網(wǎng)絡進一步規(guī)劃與調(diào)整提供依據(jù)，以保證網(wǎng)絡的業(yè)務質(zhì)量。EPON的性能管理功能分為性能監(jiān)測、性能管理控制和性能統(tǒng)計分析。性能監(jiān)測是連續(xù)的收集OLT、ONU上與性能相關的數(shù)據(jù)，根據(jù)性能數(shù)據(jù)確定

7、網(wǎng)元的性能，從而掌握設備單元因不太頻繁或間斷的差錯導致業(yè)務質(zhì)量變差的性能情況。性能管理控制的目的是支持管理人員發(fā)出控制命令或網(wǎng)管軟件自動發(fā)出控制命令，以改善OLT、ONU性能。它可以設置性能管理數(shù)據(jù)采集周期、設置性能監(jiān)測數(shù)據(jù)存儲過濾條件，并對門限值進行管理。性能統(tǒng)計分析是對收集到的性能數(shù)據(jù)做進一步的處理，以分析表或分析圖的形式報告分析結(jié)果。如計算接口利用率、接口的輸入錯誤率、接口輸出錯誤率、吞吐率等。3. 故障管理 故障管理功能提供對EPON網(wǎng)絡故障監(jiān)測、故障定位，保護切換與恢復，并存儲故障信息供以后查詢。對來自硬件設備或路徑結(jié)點的報警進行監(jiān)控、報告和存儲，對故障進行診斷、定位和處理，是故障管

8、理的重要工作。當監(jiān)測到網(wǎng)絡、設備故障或異常時，網(wǎng)管系統(tǒng)實時產(chǎn)生報警。一些故障、異常是由網(wǎng)管程序通過查詢代理站MIB發(fā)現(xiàn)的，而另一些是代理站通過Trap通知管理站發(fā)現(xiàn)的?？梢栽O置各種告警事件的告警等級。不同等級的告警事件采取不同的告警指示和處理措施。網(wǎng)管系統(tǒng)收到告警信息后，進行分析和提示，然后針對不同等級的告警，進行不同的處理。對于嚴重影響網(wǎng)絡運行的故障，需要進行故障定位和測試。啟動故障定位過程，試圖從這些過程中獲取相關信息。進行故障定位后，網(wǎng)管系統(tǒng)會盡快做出響應，采取故障修復措施，使EPON網(wǎng)絡恢復正常。告警信息被存儲到本地數(shù)據(jù)庫?？梢园凑崭婢瘯r間、告警設備、告警等級等關鍵字查詢歷史告警信息。

9、根據(jù)全部告警信息，進行告警統(tǒng)計分析，繪制出統(tǒng)計圖表。4. 安全管理 安全管理功能通過訪問操作控制策略等方法保證管理應用程序和管理信息不被非法訪問和破壞。用戶標識和鑒定，是網(wǎng)管系統(tǒng)提供的最外層的安全保護措施。網(wǎng)管用戶在啟動程序前必須輸入用戶名和登陸密碼，系統(tǒng)在核實鑒定了用戶身份以后才能提供網(wǎng)管系統(tǒng)的使用權。用戶被分為3個等級，不同等級的用戶設置不同的管理權限，第一級用戶擁有最高管理權限，可以使用網(wǎng)管系統(tǒng)提供的所有功能；低級用戶在設置參數(shù)、操作設備等權限上被限制；高級用戶擁有低級用戶的所有權限，并能對低級用戶進行管理。系統(tǒng)還提供安全日志，登陸者的所有操作將被錄入數(shù)據(jù)庫，以便維護和檢查使用。EPON

10、網(wǎng)管系統(tǒng)的實現(xiàn)EPON網(wǎng)管系統(tǒng)的實現(xiàn)包括管理站網(wǎng)管軟件的實現(xiàn)和代理站軟件的實現(xiàn)。1. 管理站網(wǎng)管軟件的實現(xiàn) 管理站網(wǎng)管系統(tǒng)是為用戶提供友好的交互式界面，利用SNMP協(xié)議對代理進程實現(xiàn)管理的控制實體。 通信模塊的功能是按照SNMP協(xié)議，對網(wǎng)絡中的代理站（OLT和ONU）發(fā)送、接收SNMP報文，從而獲取或設置代理站中MIB庫的相應信息。一方面，它將上層的操作、信息封裝成對應的PDU（協(xié)議數(shù)據(jù)單元），向網(wǎng)絡中發(fā)送。另一方面，它接收代理發(fā)給自己的PDU，并解析成上層可識別的信息，向上傳遞。對應于5種消息類型，SNMP有5種類型 數(shù)據(jù)采集、處理模塊負責將采集的數(shù)據(jù)分析、處理、儲存或者送往上層。對各種采集

11、到的數(shù)據(jù)，要按照配置、性能、故障幾個模塊的需求進行轉(zhuǎn)換，向上傳送。一些數(shù)據(jù)直接可以給上層顯示使用；一些采集到的數(shù)據(jù)需要處理后，再送往上層顯示。如通過訪問接口MIB，可以得到每個接口在每個時刻的總流量?？梢栽O置每隔一秒鐘取一次值，然后計算秒間總流量差值，得到接口每秒鐘的流量。有些數(shù)據(jù)暫時不需要顯示，需要儲存在數(shù)據(jù)庫，供以后查詢使用。 顯示模塊是面向用戶的。它按照配置管理、性能管理、故障管理、安全管理幾個模塊分類，以圖形化界面形式顯示各項信息，并且提供人機接口，供配置使用。本系統(tǒng)是在Windows環(huán)境下，用VC+ 6.0開發(fā)出來的。 通信模塊是利用Windows提供的API函數(shù)，封裝成一個SNMP

12、類，來實現(xiàn)SNMP的各種操作。按照顯示模塊的需要，數(shù)據(jù)處理模塊采用各種算法對采集到的數(shù)據(jù)進行分析處理。顯示模塊則以對話框、列表框、曲線圖等形式，提供直觀、方便的圖形化界面，如圖4所示。 2.代理站軟件的實現(xiàn)SNMP在代理站的實現(xiàn)工作主要包括代理進程軟件的實現(xiàn)和MIB的設計與組織。(1) 代理進程軟件的實現(xiàn)代理進程軟件實現(xiàn)SNMP協(xié)議，并管理MIB。它實際上是一個執(zhí)行無限循環(huán)的守護進程，在循環(huán)中，它接收管理站的SNMP請求，然后進行相應的操作，并作出響應。同時，代理進程能夠根據(jù)自身管理的MIB信息，主動向管理站發(fā)送陷阱報文（Trap），以通知管理站所管理的網(wǎng)絡設備發(fā)生了異常事件，實現(xiàn)故障告警。通

13、常，在開發(fā)過程中使用一些軟件開發(fā)包可以大大縮短產(chǎn)品開發(fā)周期。ucd-snmp軟件包是一個廣泛使用的實現(xiàn)SNMP代理開發(fā)的免費軟件包，它支持SNMP v1/v2c/v3，支持分布式代理的開發(fā)，支持MIB-II。它包括SNMP協(xié)議模塊和MIB管理模塊，實現(xiàn)了SNMP代理站的基本框架。 (2) EPON設備MIB的設計與組織OLT、ONU設備的MIB主要包括RFC1213定義的MIB-II、RFC1573定義的Interfaces MIB、RFC1493定義的Bridge MIB和根據(jù)EPON設備需要自定義的私有MIB。MIB-II包含了基于TCP/IP網(wǎng)絡的基本網(wǎng)管信息，包括系統(tǒng)組、接口組、IP組

14、、ICMP組、UDP組、SNMP組等基本管理對象。通過MIB-II，我們可以獲取OLT、ONU設備運行的基本網(wǎng)絡信息，如系統(tǒng)信息、端口基本信息、IP、ICMP等類型數(shù)據(jù)包的統(tǒng)計等，對某些對象可以配置。Interfaces MIB是針對改善MIB-II中的接口組的不足和缺陷，發(fā)展而來的一個以定義網(wǎng)絡接口管理對象為主的MIB。Bridge MIB是一個定義網(wǎng)橋管理對象的MIB，它包括一般網(wǎng)橋管理信息、生成樹網(wǎng)橋管理信息和透明網(wǎng)橋管理信息。它主要對OLT設備中所具有的生成樹網(wǎng)橋的設置、監(jiān)測提供網(wǎng)絡管理手段。自定義MIB是針對OLT、ONU特殊管理對象和特殊功能而定義的，主要包含各OLT、ONU的特殊

15、系統(tǒng)信息和帶寬控制管理兩部分。特殊系統(tǒng)信息包括硬件系統(tǒng)信息和軟件系統(tǒng)信息。如我們的EPON系統(tǒng)上行是采用WDMA方式的，對于每個ONU端，對應于不同的上行波長。把波長信息加入每個ONU的自定義MIB中，這樣通過網(wǎng)管系統(tǒng)就可以查詢各ONU的波長相關信息了。帶寬控制管理MIB是自定義MIB的一個重要部分，通過它，我們可以遠程進行基于用戶的帶寬管理。 隨著EPON的快速發(fā)展，為EPON設計和實現(xiàn)一個穩(wěn)定高效和準確的網(wǎng)絡管理系統(tǒng)具有重要的意義。本文結(jié)合EPON的特點，設計和實現(xiàn)了一個基于SNMP的EPON網(wǎng)絡管理系統(tǒng)。目前，本系統(tǒng)已經(jīng)基本完成，正在進行最后的測試工作。 Passive optical

16、network based on Ethernet EPON Ethernet passive optical network is a new optical access network technology. It has a point to multipoint architecture and passive optical transmission, basing on Ethernet provides a variety of business. It uses the PON technology in the physical layer, the link layer

17、uses the Ethernet protocol, the use of the topology of the PON to achieve the Ethernet access. Therefore, it combines the advantages of PON technology and Ethernet Technology: low cost; high bandwidth; expansion of strong, fast and flexible service restructuring; compatibility with the existing Ethe

18、rnet; convenient management and so on.Because of the many advantages of EPON, it is becoming more and more popular, and it will become one of the most effective communication methods for broadband access network. In order to ensure the stable, efficient and accurate operation of EPON network, it is

19、very important to provide an effective network management system for EPON. In the field of network management, with the development of network management technology based on TCP/IP system, SNMP has become the standard in fact. The EPON network management system based on SNMP is a system which uses t

20、he SNMP management protocol framework and the EPON network entity to realize the effective management. InIntroduction of SNMP SNMP is a network management protocol based on TCP/IP, which uses UDP as the transport layer protocol, which can manage the network equipment supporting the agency process. S

21、NMP mainly includes SMI , MIB and SNMP protocol. SMI gives the general framework of the management object definition. MIB is the structure of the entire managed object that is maintained by the device. The SNMP protocol includes SNMP operations, SNMP information format, and how to exchange messages

22、between applications and devices. The SNMP using the agent / management station model for network management. SNMP has 5 types of message types, Get-Request, Get-Next-Request, Set-Request, Trap and Get-Response. Between the agent and the management station, through the several messages to communicat

23、e each other, in order to obtain a variety of network equipment information, so as to control the normal operation of network equipment.EPON network management system structure The management object of the EPON system is 1 OLT and 32 ONU . The structure of EPON network management system based on SNM

24、P is shown in Figure 2.EMS network management system is installed on the workstation, and the OLT device is connected with the F interface. EMS network management system and OLT, ONU devices using SNMP protocol to communicate, to achieve the unified management of ONU and OLT in EMS. There are 2 ways

25、 of communication:(1) polling. Management station every time to all OLT and ONU proxy MIB to carry out the active query, each agent to return the query node value. (2) alarm (trap). When certain events occur, the broker sends a trap message to the management station. Management station to receive, d

26、isplay the alarm event, and do the appropriate processing. At the same time, the OLT equipment and ONU equipment with the local Console interface, can realize the local operation management and maintenance.Design of EPON network management systemEPON network management system is divided into four ma

27、jor modules: configuration management, performance management, fault management and security management.1 configuration management Configuration management is mainly within the organization of EPON network operation needed resources and data, construction and maintenance of network system configurat

28、ion, each network element identification, basic configuration to ensure network, monitoring the current configuration and in accordance with the specific circumstances change the configuration, the system parameter setting, to collect and store the parameters, report and basic configuration value de

29、viation, start and close the resource etc. At the start of the EPON network, can be automatically or manually generated OLT, ONU device topology, showing the current network in the ONU, OLT device status. After the network topology map is generated, the SNMP management process uses the polling metho

30、d to query the SNMP proxy process regularly, and collects the equipment information to update the database, in order to realize the configuration information. After the normal operation of the system, the network management can manually set up the configuration parameters according to the need. If w

31、e can set the OLT, ONU agent identification information and information systems to enable, disable a port, and configure the port, the working parameters of the bridge configuration, VLAN configuration, reboot the device. Also provides user based dynamic bandwidth management.2 performance management

32、 The functions of performance management of EPON network performance for monitoring, detecting and related performance statistics data acquisition, analysis, diagnosis, so as to network further planning and to provide references for the adjustment, in order to ensure the service quality of the netwo

33、rk. Performance management function of EPON is divided into performance monitoring, performance management control and performance analysis. Performance monitoring is a continuous collection of OLT and ONU and performance related data, according to the performance data to determine network performan

34、ce, so as to grasp the equipment unit business quality becomes poor performance caused from the less frequent or constant error. The purpose of the performance management control is to support the management personnel to issue control commands or network management software to automatically issue co

35、ntrol commands to improve the performance of ONU and OLT. It can set up the performance management data collection period, set up the performance monitoring data storage filtering condition, and the threshold value is managed. Performance statistics analysis is a collection of performance data to do

36、 further processing, in order to analyze the table or analysis of the results of the report analysis. Such as the calculation of the use of the interface, the interface of the input error rate, interface output error rate, throughput, etc.3 fault management Fault management function provides the EPO

37、N network fault monitoring, fault location, protection switching and recovery, and storage of fault information for future inquiries. To monitor, report and store the alarm from the hardware device or path node, and fault diagnosis, location and processing. It is an important work of fault managemen

38、t. When monitoring network, equipment malfunction or abnormal, the network management system can produce the alarm in real time. Some failures and exceptions are found by the network management program through the query agent station MIB, while others are found by the Trap notification management st

39、ation. You can set up a variety of alarm alarm level. Different levels of alarm events to take different alarm instructions and treatment measures. After receiving the alarm information, the network management system is analyzed and prompted, and then the different levels of alarm, different process

40、ing. Fault location and testing are required for the serious impact of network operation. Start the fault location process, and try to get the relevant information from these processes. After the fault location, the network management system will respond quickly, take the fault repair measures, so t

41、hat the EPON network to resume normal. Alarm information is stored to the local database. Can be in accordance with the alarm time, alarm equipment, alarm level, and other key words query historical alarm information. According to all the alarm information, alarm statistics analysis, draw a statisti

42、cal chart.4 security management Security management functions such as access control policies to ensure that management applications and management information is not illegal access and destruction. User identification and authentication is the most external security measures provided by the network

43、 management system. Network users must enter the user name and password before starting the program. The system can provide the right to use the network management system after verification and identification. User is divided into three levels, different levels of users set different management auth

44、ority, the first level user has the highest administrative authority, you can use management system to provide all of the functions; low-level users in the permission of the parameter setting and operating equipment is limited; advanced users have low-level user all the permissions, and can carry on

45、 the management to the low-level user.The system also provides a security log, all of the operator will be entered into the database, so as to maintain and check the use.Implementation of EPON network management system The realization of EPON network management system includes the realization of the

46、 management station network management software and the realization of the proxy software.1 management station network management software Management station network management system is to provide users with a friendly interactive interface, the use of SNMP protocol to achieve the management of the

47、 agent process control entities. In The function of the communication module is to transmit and receive SNMP packets according to SNMP protocol, which can obtain or set up the corresponding information of the MIB Library in the ONU. On the one hand, it will be the upper operation, the information is

48、 encapsulated into the corresponding PDU (protocol data unit), to send to the network. On the other hand, it receives the PDU that the proxy sends to its own, and is resolved into the upper layer which can be identified by the information that is transmitted to the. SNMP has 5 types, corresponding t

49、o the 5 message types The data acquisition, processing module is responsible for data collection, analysis processing, storage or sent to the upper. On the various data collected, according to the configuration, performance, failure of the needs of several modules to convert, to send. Some of the da

50、ta can be displayed directly to the upper level; some of the collected data need to be processed, and then sent to the upper display. The total flow rate at each moment can be obtained by accessing the interface MIB. You can set a value every second to take a second, and then calculate the total flo

51、w difference between seconds, get the flow of the interface per second. Some data is not required for the time being, the need to be stored in the database for future use. Display module is for the user. According to the configuration management, performance management, fault management, security ma

52、nagement of several modules to display information, and to provide a graphical interface for the use of human machine interface. This system is developed by VC+ 6 in Windows environment. Communication module is the use of API to provide the Windows function, packaged into a SNMP class, to achieve a

53、variety of SNMP operation. According to the needs of the display module, data processing module uses various algorithms to analyze and process the data collected. Display module in the form of dialog box, list box, graph, etc., to provide intuitive and convenient graphical interface, as shown in fig

54、ure 4. In2 proxy software implementation The implementation of SNMP in the proxy station mainly includes the implementation of the proxy process software and the design and organization of MIB.(1) implementation of the agent process software The SNMP protocol is implemented with the MIB protocol, an

55、d the management is implemented. It is actually a process of executing an infinite loop, in the loop, it receives the SNMP request of the management station, and then performs the corresponding operation, and makes the response. At the same time, the process agent can according to their own manageme

56、nt MIB information, take the initiative to the management station to send trap message (TRAP), to inform the management station management network equipment occurred abnormal events, and to realize the fault alarm. In general, in the development process using a number of software development package

57、 can greatly shorten the product development cycle. Ucd-snmp software package is a widely used SNMP agent to achieve the development of free software packages, which supports v1/v2c/v3 SNMP, support for the development of distributed agents, support MIB-II. It includes SNMP protocol module and MIB management module, and realizes the basic framework of SNMP proxy. In(2) the design and organization of EPON MIB ONU, OLT device MIB mainly includes the definition of MIB-II RFC1213, RFC1573 Interfaces MIB, RFC1493 definition of MIB Bridge and EPON devices based on the need to customize the privat