network management server requests to delete when deleting the log information the network element device notifies the network management server that the log information has been deleted in addition in another embodiment of the invention when the utilization of the capacity of log storage space meets a predefined condition the network element device may send the log information stored in the log storage space directly to the network management server when sending the log information stored in the log storage space directly to the network management server if receiving a reception acknowledgement message returned by the network management server the network element device deletes the log information stored in the log storage space in the embodiments of the invention the local log file for storing log information of the network element device may be of the format of an extendible marking language xml file each item of log information that is stored may include operation starting time operation ending time operation execution result ip address of operation initiator and detailed description of operation fig5 shows a network element device in a wireless metropolitan area network wman according to the invention the network element device includes a log function entity the log function entity includes a log storage module utilized as storage space of log information adapted for storing log information generated by the network element device particularly the log storage module may be a disk of a computer a monitoring module adapted for monitoring and reporting utilization status of the storage space in the log storage module and a.