The Study Of Duplicate Hot Standby System On IPDLAM

Along with the applications of current embedded design is increasingly complex, fault tolerance and high usability have become the standard system requirement. The standard technical specifications of most reliable equipments request system availability of 99.999%. The brilliant point of high usability design is to dealing with unavoidable failure economically, accordingly insuring the basic embedded functions or services are not interrupted, or reducing this interruption to the least grade.For the equipments using in communication network, the performance of high reliably running also needs to be guaranteed. From the system requirement point of view, this require the system tolerate faults, and must be maintained and upgraded without interrupting any services; from the system design point of view, the main method for high reliability is failure recovery. However, it is difficult to make the system reliability to 99.999% with single equipment, currently the actual way is to backup the important system data, and one equipment is running in active status, another one is in standby status. The standby equipment will not deal with any service messages; it only receives data from the active equipment periodically or in real time. Once there is something wrong with the active equipment, the standby one can replace it immediately to continue working, in this way the communication network will not be interrupted for a long time. From this point, we can conclude that the realization mechanism of duplicate hot standby system will be related to the overall performance of the whole communication system. On account of the differences of applications and technical backgrounds, each communication manufacturer uses different realization mechanism of duplicate hot standby system when designing their communication products. Therefore, the discussion and theory research of this technology is very little.Combining the duplicate hot standby function with active/standby mode I have done on IP DSL Access Multiplexer platform, this thesis will discuss some key functions on duplicate hot standby system such as selection of active/standby, data synchronization, switchover logic and service rapid recovery. Also it will describe the design and realization of protect management subsystem in detail as this subsystem provides perfect protect objectives to enhance the system maintainability and easily to add new management objectives as it is designed two layers for protect group and elements.At the present time, the software design and realization discussing in this thesis has already been widely applied in customers all over the world; furthermore as the good reusability of software structure, our company's other access products which implement duplicate hot standby function have reused the same one, only a little modification is needed.