Analysis of SNMP-based ROADM device network management software

1 Introduction

In recent years, the extensive development of IP, Data, video, and other services has quickly consumed optical fiber bandwidth, and the configured wavelength is gradually occupied. The development of services has shown dynamic characteristics. While expanding the capacity of the WDM system, it is bound to convert to the new generation WDM System ULH + ROADM. ROADM (Reconfigurable Optical Splitter) can meet dynamic business needs with its convenient configuration and changeable wavelength resource allocation, you can also set the number of wavelengths and specific wavelength values of the intermediate upper and lower nodes as needed to avoid wavelength blocking and build an end-to-end virtual wavelength channel [1].

ROADM is a key node of ASON. When constructing a man, ROADM equipment can not only reduce operating costs, ensure flexible business development, ensure required bandwidth, provide transparent and efficient transmission and exchange, but also achieve flexible networking, this facilitates traffic control on ASON and prepares for smooth transition to the next generation network. There are two main ways to implement ROADM: broadcast, choice, and cross-use. The broadcast/select-type ROADM device consists of tunable filters, wavelength receivers, and other devices. The demultiplexing, crossover, and multiplexing ROADM devices generally use wavelength division multiplexing and demultiplexing, coupled with controllable optical switches [2].

With the rapid development of hardware chips and processors, more processing can be performed on a single ROADM device. Therefore, you can process specific tasks on a single disk instead of using an Agent. The following describes the design and implementation of a ROADM device network management proxy. This solution does not process the performance, alarm, configuration, and proprietary commands of the ROADM device, which is simplified in the command processing module and response frame processing module. This makes the Agent design more concise and focuses on real-time device management and multi-task coordination, so that the ROADM device can respond to network management requirements in real time and report network meta information in a timely manner, work with better performance.

2SNMP Protocol

The Simple Network Management Framework Based on SNMP protocol has been rapidly promoted due to the popularity of the Internet and has become one of the most important network management technologies. SNMP is constantly evolving, and three major versions are available: SNMPv1, v2, and v3. In addition, the emergence of remote network monitoring (RMON) makes SNMP a huge step towards Distributed Management.

The Network Management Model of SNMP consists of four key parts: Manager, Agent, Management Information Library (MIB), and Network Management Protocol (SNMP ). Manager runs the SNMP Client program and network management application software. It is responsible for distributing network management commands to the Agent, extracting management information from the MIB, and reporting exceptions from the Agent. The Agent runs the SNMP Server program and MIB operation handler, receives network management commands, performs related operations on the MIB, and reports abnormal events. MIB: stores and organizes Management Information abstracted from managed network resources. SNMP: communication rules for management information exchange between managers and agents, which are generally implemented based on TCP/IP.

3 Software Design and Implementation

3.1ROADM Network Management

Network Management Model of the ROADM Device Based on SNMP protocol. As a bridge between the ROADM device and the management station, the network management Agent (Agent) is a software running on the managed device (ROADM) to perform management operations on the management process, directly operate on the local management information database [3]. The ROADM device Agent can respond to management site commands, collect ROADM device information, configure ROADM devices, send ROADM device information and command execution results to the management site, send traps to the management site, and save configuration information..

The ROADM device Agent selects the MPC860 as the hardware platform for running software, and the VxWorks embedded real-time multi-task operating system is used for the operating system. The communication between the MPC860 and each single disk of the device is implemented through the SPI port of the MPC860. In this way, real-time monitoring of devices is achieved, and good management performance is achieved.

3.2MIB Design and Implementation

According to SNMP Protocol [4], all managed objects are arranged in a tree structure, and objects at the leaf position are actually managed objects, each actual managed object represents some managed resources, activities, or related information. The tree structure itself defines a method that organizes objects into logically related sets.

The ROADM device Agent manages the system information (device name, device type, device manufacturer, device address) of the ROADM device, and the running status (alarm or normal) of the device ), slot information (slot type, slot Board information), basic information of a single disk (hardware version, software version, manufacturer information), and running status of a single disk (alarm or normal ), single disk temperature, basic port information, and port running status. Roadm mib.

3.3 software design (module division)

According to the functions required by the Agent of the ROADM device, the Agent software is divided into the following modules. Each module implements specific functions and connects them through function interfaces. The ROADM device Agent software module is shown in Figure 4.

3.4 specific implementation of each module

Upper-layer communication module: This module establishes socket connection and listens to network management requests. Parse the information source (Network Management IP address) from the received UDP packet ). And pass the data block header pointer in UDP to the Command Parsing module. The response information encapsulation module can call this module function to send Trap or response information to the network administrator. In an embedded system, port 161 is generally used as the port for receiving management station requests and sending response information to the management station, and port 162 is used to send traps to the Management Station.

Command Parsing module: This module parses the data block of the received UDP packet and obtains the Community field information for verification to ensure that the operation is legal; finally, the parsed operation object and operation parameters are passed to the command processing module, which operates the device.

Command Processing Module: This module analyzes and transfers read and write commands sent by the management station to the ROADM device. The process is shown in Figure 5. First, the system receives the operation objects and operation parameters passed by the Command Parsing module. Then, analyze the operation object and find the corresponding device attributes (Equipment attributes, Slot attributes, Card attributes, or Port attributes) through the OID ). Device properties and property values are converted into hexadecimal numbers that can be recognized by the hardware according to the hardware layer protocol, encapsulated into data frames, and transmitted to the lower-layer communication module.

Response frame processing module: This module processes the reported information and response frames sent from the lower-layer communication module, parses the corresponding managed object attributes (OID) and managed object attribute values, it is passed to the response information encapsulation module and updated to the database through interface functions. Send Trap to Manager when there are alarms and important information.

Response Information encapsulation module: This module binds the received managed object attributes (OID) and their attribute values to the corresponding PDU (Protocol Data Unit) package, add the community name and version number to the upper-layer communication module.

Configuration Module: when the network administrator issues the Set command, if a Set success message is returned in the response frame, the notification configuration module stores the new configuration data in the database. When the system restarts, the module reads the last configuration data from the database and configures the device through the command processing module.

Lower-layer communication module: This module establishes two message queues, one for sending data to the ROADM device, and the other for receiving response frames from the ROADM device. Transparent transmission of interaction information to complete communication between Agent software and ROADM devices.

4 Conclusion

The Application of ROADM in local/metro networks has aroused the enthusiastic attention of equipment manufacturers and operators. In particular, foreign operators are very enthusiastic about ROADM. They all have the idea of using ROADM to upgrade their basic network and are ready to deploy ROADM technology in the future.

1. Use SNMP to manage Cisco devices
2. Enterprise Network focuses on management network management software