1. Field of the Invention
The present invention relates to a management system for a network. More particularly, it relates to a network management system in a large-scalenetwork which is constituted by a large number of nodes, and in which the nodes are structurally complicated and require many sorts of status information on subjects to-be-managed.
2. Description of the Related Art
In a network such as local area network (LAN) or wide area network (WAN), the simple network management protocol (SNMP) being the network management protocol of the Internet conformed to the TCP/IP (Transmission Control Protocol/Internet Protocol), with which even different types of machines can be managed by common specifications, is adopted as a protocol for managing the network.
FIG. 1A is a diagram for explaining the outline of a network management system based on the SNMP. In a management model adopted in the SNMP, a protocol for managing the Internet works in the application layer of the TCP/IP, and a manager and a managee assume the form of a client and a server. Referring to FIG. 1A, a managing apparatus 100 functions as the client and operates as the manager 102. An apparatus to-be-managed 101 functions as the server and operates as an agent 103.
The apparatus to-be-managed 101 includes therein a database 104 called "management information base (MIB)" in which status information items on subjects for management, for example, various modules constituting a node, lines etc. are accumulated.
With the SNMP, by way of example, the manager 102 requests the agent 103 to get the value of status information (an object) on a subject for management, through a GET request. The agent 103 responds to the request as a GET response, and notifies the status information to the manager 102 as information necessary for the management. Besides, the agent 103 notifies an abnormal situation or the like having occurred on the side of the apparatus to-be-managed 101, to the manager 102 through a TRAP. Employed here is a system wherein the manager 102 sends the GET requests to the agent 103 at, for example, regular intervals, thereby to poll the information necessary for the management.
FIG. 1B is a diagram for explaining a network management system in a local area network which utilizes the SNMP. Referring to the figure, a network managing apparatus 100 is connected to the local area network 106 in which a plurality of workstations 105 are interconnected. Information items (objects) to be managed for each workstation 105 are the two items of a system status and an interface (port) status. The network managing apparatus 100 manages the network by periodically repeating supervision sequences for the respective workstations 105, each of the sequence for one workstation 105 consisting of a GET request for acquiring the system status, a response to the request for the system status by the workstation 105, a GET request for acquiring the interface status, and a response to the request for the interface status.
Heretofore, apparatuses to be managed by the SNMP have usually been workstations which constitute a local area network, and routers, bridges, hubs etc. which interconnect LANs. As information items (objects) on the subjects to-be-managed, it has sufficed to define a comparatively small number of objects, for example, two objects for one workstation as explained with reference to FIG. 1B.
Recently, however, the structure of a node (apparatus) which constitutes a WAN, especially an ATM (Asynchronous Transfer Mode)-WAN, has become complicated, and the objects of subjects for management (the status information items of various control modules including line control modules, trunk lines, terminal lines, etc. as constitute the apparatus) have become large in the number of sorts and large in quantities. Moreover, the number of nodes constituting the network has enlarged to increase the loads of a manager in an MIB information acquisition process for one agent and in MIB information acquisition processes for many agents. This has led to the problem that a status information polling period for all the agents lengthens, making it difficult to incarnate the real time management of the network. In other words, the management of such a large-scale network by the use of the SNMP necessitates the adoption of a dedicated apparatus of high price and high performance or the installation of a plurality of manager apparatuses.