Abstract:
A network address assigning system includes sub-networks connected to each other, a network composed of the sub-networks connected to each other, an address server for managing network addresses of the sub-net-works, nodes for transmitting and receiving messages over the sub-networks, routing nodes for transmitting and receiving messages, for transferring messages over the sub-networks, and for managing addresses of the sub-networks, a change indicator for causing the address server to re-assign network addresses of the sub-networks and for causing the routing nodes to notify the address server of the network addresses of the routing nodes, storage for causing the address server to store address information, and a notifier for causing the address server to communicate with the routing nodes and to notify the routing nodes of network address information that has been newly registered/changed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a network address assigning system, in particular, to a network address assigning system for managing addresses of a network and sub-networks such as LAN (Local Area Network), WAN (Wide Area Network), Intra-Net, and Extra-Net. 
     2. Description of the Related Art 
     Whenever a node is newly added or moved, terminal addresses/IP addresses of a conventional computer network are individually aligned/changed. 
     In Japanese Patent Laid-Open Publication No. 9-130421 as a first related art reference of the present invention, a terminal address management system corresponding to a virtual network management method is disclosed. In the terminal address management system, a management table for managing a MAC (Media Area Control) address, VLAN (Virtual Local Address Network) identifier, a switching hub identifier, and a port number is used. The MAC address is used for identifying a LAN board of a computer. In the first related art reference, network addresses are intensively managed by an address server. 
     In Japanese Patent Laid-Open Publication No. 8-194657 as a second related art reference of the present invention, an IP address automatic assigning system for portable terminals connected to a local area network is disclosed. The system is used for an automatic Internet program apparatus. In the second related art reference, network addresses are intensively managed by an address server. 
     In Japanese Patent Laid-Open Publication No. 6-062020 as a third related art reference of the present invention, a computer network structuring/modifying system is disclosed. In the system, addresses are changed and reused corresponding to the movement of a node. In the third related art reference, network addresses are intensively managed by an address server. 
     In Japanese Patent Laid-Open Publication No. 8-204719 as a fourth related art reference of the present invention, an IP address assigning apparatus and an IP address assigning method are disclosed. In the fourth related art reference, terminal addresses are managed by a terminal IP address management server. 
     In Japanese Patent Laid-Open Publication No. 2-222336 as a fifth related art reference of the present invention, a computer address management system is disclosed. In the fifth related art reference, a terminal inquires a local address of an address server. 
     In Japanese Patent Laid-Open Publication No. 5-028065 as a sixth related art reference of the present invention, an information processing system is disclosed. In the sixth related art reference, an address management server automatically assigns an address of a client corresponding to an address assignment request issued therefrom. 
     In Japanese Patent Laid-Open Publication No. 61-123232 as a seventh related art reference of the present invention, an address assigning system for a local area network system is disclosed. The structure of the address assigning system is shown in FIG.  1 . Referring to FIG. 1, an address server  1  manages addresses of nodes  10 ,  11 ,  12 , and  13  of sub-networks  17 ,  18 , and  19  of routing nodes  2 ,  3 ,  4 , and  5  as well as addresses of routing nodes  2 ,  3 ,  4 , and  5  of a main-network  16 . Thus, for example, whenever a node is added or deleted, the contents of a destination address table for all nodes should be updated. Thus, to flexibly operate the system, the routing nodes  2  to  5  have respective address server functions so as to distributively manage addresses. 
     In the first related art reference, the address server does not totally manage the full network as a set of routing nodes and sub-networks thereof. In other words, network addresses of the sub-networks cannot be assigned and managed. Thus, the system of the first related art reference cannot handle the movement of a sub-network. In addition, since the address server does not communicate with the routing nodes, network addresses cannot be totally assigned over the network. 
     In the second related art reference, the address server does not totally manage the network as a set of routing nodes and sub-networks. In addition, addresses of the sub-networks are not assigned and managed. Consequently, the system of the second related art reference cannot handle the movement of a sub-network. In addition, since the address server does not communicate with the routing nodes, network addresses cannot be totally assigned over the network. 
     In the third related art reference, address servers are disposed corresponding to individual domains. Since terminal addresses are managed in association with node names, the address management servers do not assign and manage addresses of sub-networks. 
     In the fourth related art reference, network addresses are not managed. In the fifth related art reference, although the address server manages terminal addresses, it does not manage network addresses. 
     In the sixth related art reference, although the address server manages client addresses, it does not manage network addresses. 
     In the seventh related art reference, addresses are hierarchically managed corresponding to an expansion or a deletion of a node in a sub-network. However, in the seventh related art reference, the movement of a sub-network and the movement of both a sub-network and a routing node at a time are not mentioned at all. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a system that handles the movement of both a routing node and a sub-network thereof at a time and that manages addresses in a multi-home format. 
     The present invention is a network address assigning system, comprising a plurality of sub-networks directly communicated with each other, a network composed of the sub-networks connected to each other, an address server for managing network addresses of the sub-networks, a plurality of nodes for transmitting and receiving messages over the sub-networks, a plurality of routing nodes each having a node function for transmitting and receiving a message, a router function for transferring a message over the sub-networks, and an address management function for managing addresses of the sub-networks, a change indicator for causing the address server to re-assign network addresses of the sub-networks and for causing the routing nodes to notify the address server of network addresses of the routing nodes, storage for causing the address server to store address information, and a notifier for causing the address server to communicate with the routing nodes and to notify the routing nodes of network address information that has been newly registered/changed. 
     When the network address information is registered by the change notifier, the address server does not notify the routing nodes of the network address information that has been newly registered/changed. 
     The routing nodes each have a means for inquiring data of the address server, and a means for obtaining the latest address information of the network. 
     IP (Internet Protocol) datagram (a kind of packet) is transferred corresponding to a network address assignment table physically stored by the address server and the sub-networks of the routing nodes. 
     These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a schematic diagram showing the structure of a conventional system; 
     FIG. 2 is a schematic diagram showing the structure of a system according to an embodiment of the present invention; 
     FIGS. 3A,  3 B,  3 C, and  3 D are flow charts for explaining the operation of the system according to an embodiment of the present invention; 
     FIG. 4 is a schematic diagram showing the structure of a network according to an embodiment of the present invention; 
     FIG. 5 is a schematic diagram showing the structure of the network according to an embodiment of the present invention; 
     FIG. 6 is a schematic diagram showing the structure of the network according to an embodiment of the present invention; 
     FIG. 7 is a schematic diagram showing the structure of the network according to an embodiment of the present invention; 
     FIG. 8 is a schematic diagram showing the structure of the network according to an embodiment of the present invention; 
     FIG. 9 is a schematic diagram showing the structure of the network according to an embodiment of the present invention; and 
     FIG. 10 is a schematic diagram showing the structure of the network according to an embodiment of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Next, with reference to the accompanying drawings, embodiments of the present invention will be described. 
     [First Embodiment] 
     (Structure of First Embodiment) 
     FIG. 2 shows the structure of a network address assigning system according to the first embodiment of the present invention. 
     In the first embodiment, a program address server  1  is disposed in a main network  16 . The program address server  1  manages network addresses assigned to routing nodes  2 ,  3 ,  4 ,  5 ,  6 ,  7 , and  9  and addresses assigned to sub-networks  17 ,  18 , and  19 . The sub-networks  17  to  19  are connected to the routing nodes  2  to  9 . The sub-network  17  has nodes  10  and  11 . The sub-network  18  has nodes  12  and  13 . The sub-network  19  has nodes  14  and  15 . The nodes  10  to  15  transmit and receive datagram (that is a short message composed of one packet) corresponding to IP (Internet Protocol). The nodes  10  and  11  connected to the routing node  6 . The nodes  12  and  13  are connect to the routing node  7 . The nodes  14  and  15  are connected to the routing node  8 . Each of the routing nodes  2  to  9  transfers datagram corresponding to a destination address of the network as shown in FIG.  2 . 
     Each of the routing nodes  2  to  9  decides the address of a received datagram and transfers the datagram to a routing node that manages a destination sub-network (hereinafter, such a process is referred to as address deciding process). 
     The address deciding process is performed in two methods that follow. In the first method, an address is decided with address information of another routing node received from the address server  1  (see FIG.  4 ). In the second method, an address is decided with an inquiry to the address server  1  (see FIG.  5 ). 
     FIG. 4 shows the first method of the address deciding process. Referring to FIG. 4, an address server  1  notifies routing nodes  2  to  5  connected to a main network  16  of addresses of the routing nodes  2  to  5 . When a network address of a routing node is changed, the address server  1  notifies other routing nodes of relevant address change information. 
     FIG. 5 shows the second method of the address deciding process. Referring to FIG. 5, a routing node  2  to  5  of a main network  16  inquires of an address server  1  a destination address. The address server  1  notifies the routing node of the destination address. In addition, the address server  1  replies of a particular routing node data for the address deciding process. 
     FIG. 6 shows the movement of a routing node. Referring to FIG.  6 , when a routing node  3  is moved from the position under a routing node  2  to the position under a node  4 , at the position under the routing node  2 , the routing node  3  notifies an address server  1  of the movement. After the routing node  3  has been moved to the position under the routing node  6 , the routing node  3  notifies the address server  1  of the movement. Thus, the address server  1  can always manage addresses of a routing node that moves. 
     FIG. 7 shows an address re-assignment in the case of the movement of a routing node. Referring to FIG. 7, when a routing node  3  that has a sub-network  17  is moved from the positon under a routing node  2  to the position under a routing node  6 , the routing node  5  notifies an address server  1  of the movement. The address server  1  notifies the routing node  5  of a re-assigned address. 
     FIG. 8 shows an address notification in the case of the movement of a routing node. Referring to FIG. 8, when a routing node  3  that has a sub-network  17  is moved from the position under a routing node  2  to the position under a routing node  6 , the routing node  3  notifies an address server  1  of the movement. The address server  1  notifies the routing node  5  of a re-assigned address. In addition, the address server  1  simultaneously notifies other routing nodes of the re-assigned address of the routing node  3 . 
     FIG. 9 shows an address management of a main network  16 . 
     Referring to FIG. 9, whenever a routing node is moved or the address thereof is changed, an address server  1  notifies other routing nodes of the movement or change of the address. 
     FIG. 10 shows a multi-home of a simultaneous notification of an address server  1  of a main network  16 . Referring to FIG. 10, when a routing node  3  that has a sub-network  17  is moved from the position under a routing node  2  to the position under a routing node  6 , the outing node  5  notifies the address server  1  of the movement. The address server  1  simultaneously notifies other routing nodes of the address of the routing node  5  in the multi-home format. 
     (Operation of First Embodiment) 
     Next, with reference to FIGS. 2,  3 A,  3 B,  3 C, and  3 D, the operation of the system according to the first embodiment of the present invention will be described. 
     The address server  1  assigns network addresses of the sub-networks  17  to  19  to the routing nodes  2  to  9  (at step S 1 ). 
     The routing nodes  2  to  9  assign local addresses to the local nodes  10  to  15  of their sub-networks  17  to  19  (at step S 2 ). The routing nodes  2  to  9  have completely assigned local addresses to the local nodes  10  to  15  (at step S 2   a ). 
     A routing node issues a communication request to transmit data (at step S 2   b ). The routing node determines whether or not there is a destination address (at step S 2   e ). When the determined result at step S 2   e  is No, the routing node inquires of the address server  1  a destination address (at step S 3 ). 
     When the routing node inquires of the address server  1  the destination address, the address server  1  notifies the routing node of the address of a destination routing node (at step S 4 ). 
     The routing node performs a transfer process corresponding to the destination address (at step S 5 ). After the routing node has completed the transfer process, the network becomes idle (at step S 5   a ). 
     When a sub-network has been moved (at step S 2   c ), the relevant routing node notifies the address server  1  of the movement (at step S 6 ). 
     Thereafter, the address server  1  notifies other routing nodes of the movement of the relevant sub-network (routing node) (at step S 7 ). After the address server  1  has completed the notification process, the network becomes idle (at step S 7   a ). 
     When a network structure is changed or a network address is re-assigned (at step S 2   d ), the address server  1  notifies a relevant routing node of a re-assignment of the address (at step S 8 ). 
     Thereafter, the address server  1  notifies other routing nodes of the re-assignment of the address of the relevant routing node (sub-network) (at step S 9 ). After the address server  1  has completed the notification process, the network becomes idle (at step S 9   a ). 
     Thus, the address server  1  always manages addresses of routing nodes corresponding to the above-described flow chart. 
     [Second Embodiment] 
     Next, with reference to the accompanying drawings, a second embodiment of the present invention will be described. 
     (1) Movement 
     When a routing node  3  and a sub-network  17  thereof are moved, at the original position and at the destination position, the routing node  3  notifies the address server  1  of the movement (see FIG.  6 ). 
     (1.1) Movement (address assignment method) 
     FIG. 4 shows an address re-assigning method of which the address server  1  assigns a new address to a routing node that has been moved. When a routing node  3  that has a sub-network  17  is moved to the position of a routing node  5  that has a sub-network  19 , the address server  1  assigns a new address to the routing node  3 . In addition, the address server  1  notifies the routing nodes  2  to  4  of the new address of the routing node  3 . 
     (1.2) Movement (movement notification method) 
     FIG. 5 shows a movement notification method of which the address server  1  notifies other routing nodes of the movement of a routing node without re-assigning the address of the routing node. When a routing node  3  that has a sub-network  17  notifies the address server  1  of the movement to the position of a routing node  5  that has a sub-network  19 , the address server  1  notifies other routing nodes of the movement. In addition, the routing node  3  notifies the local nodes of the movement. 
     (2) Address management (network) 
     FIG. 9 shows a change of the network structure due to an increase/decrease of users in a particular region. When the network structure is changed due to an increase or decrease of the number of users in a particular region, as shown in FIG. 9, addresses of routing nodes are re-assigned so as to easily route nodes. 
     (3) Address management (node) 
     Each routing node has a firewall function that prevents the security of local host terminals against illegal accesses from the outside of the system (namely, the firewall function is for example NAT (Network Address Translator) that converts an IP address of a company into another address). Thus, in a sub-network of each routing node, addresses can be freely assigned. In this case, the routing node notifies all routing nodes in the main network of the re-assigned addresses. 
     (4) Multi-home 
     FIG. 10 shows a multi-home connection structure. In the multi-home connection structure of which a sub-network of a routing node is connected to a higher hierarchical network at several points, by re-assigning addresses, troubles and congestion can be prevented. Conventionally, paths can be changed locally, not globally. 
     In addition, the load can be shared by dynamically re-assigning addresses corresponding to the results of the traffic supervisory. When a defect takes place in a sub-network, by re-assigning the address thereof, a connection route through such a defective sub-network can be changed. 
     (Operation of Second Embodiment) 
     Next, with reference to FIGS. 4 to  10 , the operation of the second embodiment of the present invention will be described in detail. 
     As shown in FIG. 4, the address server  1  assigns physical addresses to the routing nodes  2  to  7 . In addition, the address server  1  assigns IP addresses to sub-networks of the routing nodes  2  to  7 . 
     When the network scale and/or structure is changed, the address server  1  re-assigns physical addresses and IP addresses of the routing nodes and the sub-networks. 
     As shown in FIG. 5, when a node ( 10  to  12 ) of the local sub-network of the routing node  3  issues a communication request to the node  13  of the sub-network of the routing node  5 , the routing node  3  inquires of the address server  1  the physical address of the routing node  5  that has the destination node  13  (sub-network). The routing node  3  obtains the physical address of the routing node  5  from the address server  1  and transfers data to the physical address of the routing node  5 . 
     As shown in FIG. 6, the routing node  3  and the sub-network  17  thereof are moved from the position under the routing node  2  to the position under the routing node  6 . At this point, before the routing node  3  is moved, the routing node  3  notifies the address server  1  of the movement. 
     As shown in FIG. 7, the address server  1  assigns a new physical address to the routing node  5 . At this point, after the routing node  3  has been moved, an IP address node of the sub-network  17  of the routing node  3  notifies the address server  1  of the movement. In this case, the IP address may not be re-assigned. 
     As shown in FIG. 8, the address server  1  notifies other routing nodes of the movement of the routing node  3 . In addition, the address server  1  notifies other routing nodes of the new physical address of the routing node  3 . FIG. 9 shows a local address re-assignment as an address management in the case that the routing node  3  is moved to the position of the routing node  5 . FIG. 10 shows a multi-home network structure of which the address of the sub-network of the routing node  3  moved to the position of the routing node  5  is managed as one-home movement. 
     As described above, according to the present invention, the address server assigns physical addresses of routing nodes and addresses of sub-networks. Each routing node assigns an address assigned by the address server to the sub-network. When the sub-network is moved, the routing node notifies the address server of the movement. The address server assigns a physical address of the destination to the moved routing node. The address of the moved sub-network may not be re-assigned. The address server notifies other routing nodes of the address information of the moved routing node. 
     When a physical address having a geographical and hierarchical structure corresponding to E.164 standard is used for a transfer address of the network, data can be transferred over the network regardless of logical addresses of sub-networks. In other words, with physical addresses having geographical and hierarchical structure corresponding to E.164 standard, the physical position of a destination can be obtained regardless of the address. Thus, addresses can be freely assigned in sub-networks. 
     Although the present invention has been shown and described with respect to a best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the present invention.