With the wide applications of the Multi-Service Access Platform（MSAP） system

its maintenance has become increasingly important

especially in respect of the upgrade of the remote devices.This article presents a method for the automatic online upgrading of all nodes in the MSAP system.The upgrading starts from its Digit cross-connect Manager Unit（DMU） and the DMU downloads the upgrading program from the server via the standard FTP and implements data validation.Every node in the MSAP system delivers the program to the subordinate devices through the store-and-forward mechanism.DMU can monitor the entire upgrading process via the feedback mechanism and ensure the success of the upgrading.The results indicate that the devices in the MSAP system can be effectively

steadily and automatically upgraded online

the users can monitor the upgrading process of the devices through DMU serial port and this method is applicable to any hierarchical systems.