Abstract:
A network management system that is capable of managing each device in an information processing device efficiently even though on a network there are a plurality of the information processing apparatuses which search for devices to manage. A network management system comprises a multi-function printer (MFP) connected to a network, and a network management station that searches and manages the MFP. The MFP comprises a search source information recording unit that records information related to the network management station, which is a transmitter of a search packet, as search source information in response to receipt of the search packet, and a search source information transmitting unit that transmits the search source information to the network management station in response to request from the network management station. The network management station comprises a search source information acquisition requesting unit that requests acquisition of the search source information to the device, and a search source information obtaining unit that obtains the search source information transmitted from the MFP.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a network management system that manages devices connected to a network, a network management method, an information processing apparatus, a device, and a storage medium. 
     2. Description of the Related Art 
     Conventionally, a network management station, namely an information processing apparatus such as a personal computer manages a state of various devices (managed object nodes) connected to a network. In most cases, the network management station manages the whole network independently. In recent years, a demand for equipping and managing a plurality of network management stations has been increasing. However, a conventional operation of a plurality of the network management stations causes problems that a plurality of the network management stations perform settings contradictory each other to one of the devices (managed object node), which leads to incorrect settings as a result. 
     To this end, reduction in network load and unified management have been wanted to be realized by separating the search range among a plurality of the set network management stations and sharing the collected information one another. A system in which a plurality of the network management stations search for mutual existence and work together has been needed in order to fulfill the above demand. 
     Conventionally, each of the network management stations has searched for another of the network management stations by means of broadcast in order to search for the mutual existence (see e.g. Japanese Laid-Open Patent Publication (Kokai) No. 2003-216572), or the direct communication protocol has searched for another of the network management stations. 
     On the other hand, the network management station has needed to search for devices connected to the network managed by itself in order to realize its original purpose. 
     However, as in the above-mentioned prior art example, there has been a problem mentioned-below when each of the network management stations searches for another of the network management station by means of the broadcast or the direct communication protocol. Namely, this kind of search has caused very low efficiency in use of the network. Especially, it has increased traffic on the network to search frequently for nodes (devices), whose addresses on the network are not known preliminarily, by means of the broadcast or the direct communication protocol. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a network management system that is capable of managing each device in an information processing device efficiently even though on a network there are a plurality of the information processing apparatuses which search for devices to manage, and a network management method therefor an information processing apparatus, a device and a storage medium. 
     To attain the above-mentioned object, according to a first aspect of the present invention, there is provided a network management system comprising a device connected to a network, and an information processing apparatus that searches and manages the device, wherein the device comprises: a search source information recording unit that records information related to the information processing apparatus, which is a transmitter of a search packet, as search source information in response to receipt of the search packet; and a search source information transmitting unit that transmits the search source information to the information processing apparatus in response to request from the information processing apparatus, and the information processing apparatus comprises: a search source information acquisition requesting unit that requests acquisition of the search source information to the device; and a search source information obtaining unit that obtains the search source information transmitted from the device. 
     The search source information preferably includes a network address. 
     The search source information further preferably includes hardware identification information, the device preferably comprises a hardware identification information determining unit that determines whether or not the hardware identification information of the search source is recorded in the search source information when the device itself is searched by the information processing apparatus, and the search source information recording unit, when the hardware identification information of the search source is determined to be already recorded, preferably, records the network address used in the search in the search source information, deletes the recorded information of the previous search by the same hardware identification information from the search source information, and holds the recorded information related to the information processing apparatuses that are identical in a network address with each other and different in hardware identification information from each other, without deleting the recorded information from the search source information. 
     The search source information preferably further includes the type of the search manner, the device preferably comprises a search manner determining unit that determines whether or not the type of the search manner included in the recorded information is the same as the type of the search manner in the present search when the hardware identification of the search source is already recorded in the search source information, wherein the recorded information is deleted from the search source information when the type of the search method is the same, and the recorded information is not deleted from the search source information when the type of the search method is different. 
     The information processing apparatus preferably comprises a confirmation request transmitting unit that transmits to one of the information processing apparatuses a request to confirm whether or not it is the same type of the information processing apparatus as its own, a network address recording unit that records a network address of the one of the information processing apparatuses which is confirmed to be the same type of the information processing apparatus as its own, a determination unit that determines whether or not a transmitter of the request is the same type of the information processing apparatus as its own when the request is received from another of the information-processing apparatuses, and a determination result transmitting unit that transmits a result of the determination to the another of the information processing apparatuses. 
     To attain the above-mentioned object, according to a second aspect of the present invention, there is provided a network management method in a network management system comprising a device connected to a network, and an information processing apparatus that searches and manages the device, wherein the device records information related to the information-processing apparatus, which is a transmitter of a search packet, as search source information in response to receipt of the search packet; and transmits the search source information to the information processing apparatus in response to request from the information-processing apparatus, and the information-processing apparatus requests acquisition of the search source information to the device; and obtains the search source information transmitted from the device. 
     To attain the above-mentioned object, according to a third aspect of the present invention, there is provided an information processing apparatus that searches and manages a device connected to a network, comprising: a search source information acquisition requesting unit that requests acquisition of the search source information to the device; and a search source information obtaining unit that obtains the search source information transmitted from the device. 
     To attain the above-mentioned object, according to a fourth aspect of the present invention, there is provided a device that is connected to a network and searched by an information processing apparatus, comprising: a search source information recording unit that records information related to the information processing apparatus, which is a transmitter of a search packet, as search source information in response to receipt of the search packet; and a search source information transmitting unit that transmits the search source information to the information processing apparatus in response to request from the information processing apparatus, 
     According to a fifth aspect of the present invention, there is provided a program for causing a computer to execute the above-mentioned network management method. 
     According to a sixth aspect of the present invention, there is provided a computer-readable storage medium storing the above-mentioned program. 
     According to the present invention, it is possible to manage each device in an information processing apparatus efficiently even though on a network there are a plurality of the information processing apparatuses which search for devices to manage. 
     The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view schematically showing the construction of a network management system according to a first embodiment of the present invention; 
         FIG. 2  is a block diagram of the construction of a network management station; 
         FIG. 3  is a block diagram of the hardware construction of management object nodes, namely MFPs; 
         FIG. 4  is a flowchart showing the procedures for carrying out a process of receiving a search packet in a network controller in the MFP; 
         FIG. 5  is a view showing an example of a search source list; 
         FIG. 6  is a flowchart showing the procedures for carrying out a process for a search source list request packet among the procedures in the step S 8  in  FIG. 4 ; 
         FIG. 7  is a flowchart showing the procedures for carrying out a response process to network management station information inquiry in the network management station; 
         FIG. 8  is a flowchart showing the procedures for carrying out a process of obtaining a search source list in the network management station, and the procedure for carrying out a process of searching another network management station on the same network; 
         FIG. 9  is a flowchart, continued from  FIG. 8 , showing the procedures for carrying out a process of obtaining a search source list in the network management station, and the procedures for carrying out a process of searching another network management station on the same network; 
         FIG. 10  is a view showing an example of a managed object node list; 
         FIG. 11  is a view showing a network management station list; 
         FIG. 12  is a flowchart showing the procedures for carrying out a process of receiving a request for the managed object node list as a process according to the other received packet in the step S 25  in  FIG. 7 ; 
         FIG. 13  is a flowchart showing the procedures for carrying out a process of receiving a request for the managed object node list as a process according to the other received packet in the step S 64  in  FIG. 12 ; 
         FIG. 14  is a flowchart showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station; 
         FIG. 15  is a flowchart, continued from  FIG. 14 , showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station; 
         FIG. 16  is a view showing the flow of the entire process in the network management system; 
         FIG. 17  is a view showing the flow of the other entire process in the network management system; 
         FIG. 18  is a flowchart showing the procedures for carrying out a process of receiving the search packet in the network controller in the managed object node, namely the MFP according to a second embodiment of the present invention; 
         FIG. 19  is a table showing an example of the search source list held by the managed object node; 
         FIG. 20  is a flowchart showing the procedures for carrying out a process of receiving the search packet in the network controller in the managed object node, namely the MFP according to a third embodiment of the present invention; 
         FIG. 21  is a flowchart, continued from  FIG. 20 , showing the procedures for carrying out a process of receiving the search packet in the network controller in the managed object node, namely the MFP; 
         FIG. 22  a table showing an example of the search source list held by the managed object node; 
         FIG. 23  is a flowchart showing the procedures for carrying out a process of collecting information on the management object nodes in the network management station; 
         FIG. 24  is a flowchart, continued from  FIG. 23 , showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station; 
         FIG. 25  is a flowchart, continued from  FIGS. 23 and 24 , showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station; and 
         FIG. 26  is a flowchart, continued from  FIGS. 23 ,  24  and  25 , showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described in detail below with reference to the drawings. 
     A network management system according to a first embodiment of the present invention will be now described below. 
       FIG. 1  is a diagram schematically showing the configuration of a network management system according to a first embodiment of the present invention. The network management system is provided with a first network  101 , a second network  102 , and a router  103  connecting the first network and the second network to each other. To the first network  101  is connected a network management station  106 , and multi-function printers (MFPs)  104 ,  105  and  107 , namely devices as managed objects of the network management station  106 , whereas to the second network  102  is connected a work station computer  108 , and a network management station  109 , MFPs  110  and  111 , namely devices as managed objects of the network management station  109 . 
       FIG. 2  is a block diagram of the configuration of the network management station  106  or  109 . The network management station  106  or  109  is comprised of an information-processing apparatus such as a personal computer. In the network management station  106  or  109 , a CPU  203 , a ROM  205 , a RAM  206 , and a network I/F  207  that are well-known are connected with one another via a bus  204 . Further, A display I/F  208 , an input device I/F  210 , and a secondary memory I/F  212  are connected to the bus  204 . 
     The network I/F  207  connects the bus  204  and the network  101  ( 102 ) to each other. The display I/F  208  connects a display  209  connected thereto and the bus  204 . 
     The input device I/F  210  connects an input device  211  connected thereto and the bus  204 , and the secondary memory I/F  212  connects a secondary memory device  213  connected thereto and the bus  204 . 
       FIG. 3  is a block diagram showing the hardware construction of the MFP  104 ,  105 ,  107 ,  110 , or  111 , as a managed object node. The MFP has an MFP main body  302  having functions of print, copy, and facsimile, and a network controller  303  that connects the MFP main body to a network  101  ( 102 ). 
     The network controller  303  is provided with a CPU  305 , a ROM  307 , a RAM  308 , and a network I/F  309  that are connected with one another via a bus  306 . To the bus  306  is connected a host I/F  310  that connects the MFP main body  302  to the bus  306 , and a management information base (MIB)  311  that stores information for network management. 
     Operation of the network management system that has the above-mentioned configuration will be shown below.  FIG. 4  is a flowchart showing the procedures for carrying out a process of receiving a search packet in the network controller  303  in the MFP. The program for the process is stored in the ROM  307  in the network controller  303 , and executed by the CPU  305 . 
     In this context, the search packet is designed for a packet in which the network management stations  106  or  109  checking whether there are any network nodes as managed objects on the network  101  or  102 . In this embodiment, for example, the search packet includes a GET packet in which a command according to SNMP (Simple Network Management Protocol) to get a particular object ID is broadcasted, or unicasted. Otherwise, the search packet may be a pattern of a network packet used for search as a rule on the system. In this case, the network management stations  106  and  109 , and the MFP  104 ,  105 ,  107 ,  110  and  111  as the managed object nodes are supposed to know such a pattern in advance. 
     In  FIG. 4 , first of all, it is checked whether there is any received packet or not (step S 1 ). It is determined whether there is any received packet or not (step S 2 ). When there is no received packet, the process returns to the step S 1 . On the other hand, when there is a received packet, the received packet is read into the RAM  308  (step S 3 ). 
     Then, it is determined whether the received packet is a search packet or not (step S 4 ). When the received packet is not a search packet, the received packet is subjected to the other process according to the type of the received packet (step S 8 ), followed by terminating the process. 
     On the other hand, when the received packet is a search packet, the packet stored in the RAM  308  is analyzed, and a network address of the transmitter of the packet is obtained, and then added to a “search source list” allocated to the RAM  308  (step S 5 ). Then, a response to the search packet is prepared (step S 6 ), and the prepared response is transmitted (step S 7 ), followed by terminating the process. 
       FIG. 5  is a view showing an example of a search source list. In  FIG. 5 , the search source list  410  registers network addresses of the search sources from which the MFP has received search packets so far. Specifically, the registered network addresses are comprised of 172.xx.yy.zz, 172.aa.bb.cc, 172.rr.ss.tt, 172.lll.mm.nn, etc. 
       FIG. 6  is a flowchart showing the procedures for carrying out a process for a search source list request packet among the process executed in the step S 8  in  FIG. 4 . The received packets are written into the RAM  308  due to the procedures taken so far. It is also confirmed that the received packets are not the search packets 
     In  FIG. 6 , first, it is determined whether the received packet is a search source list request packet or not (step S 11 ). When the received packet is not a search source list request packet, the received packet is subjected to the other process according to the type of the received packet (step S 12 ), followed by the process returning to the main flow. 
     On the other hand, when the packet received in the step  11  is a search source list request packet, the search source list (see  FIG. 5 ) stored in the RAM  308  is read out, a response to the search source list request is prepared (step S 13 ), and the prepared response is transmitted (step S 14 ), followed by the process returning to the main flow. 
       FIG. 7  is a flowchart showing the procedures for carrying out a response process to a network management station information inquiry in the network management station  106  or  109 . The program for the response process is stored in a recording medium (ROM  205 , secondary memory  213 ) in the network management station  106  or  109 , and executed by the CPU  203 . 
     In  FIG. 7 , first, it is checked whether there is any received packet or not (step S 21 ). As a result of the check, it is determined whether there is any received packet or not (step S 22 ). When there is no received packet, the process returns to the step S 21 . 
     When there is a packet received in the step S 21 , the received packet is read into the RAM  206  (step S 23 ). Then, it is determined whether or not the received packet is a network management station information inquiry (step S 24 ) When the received packet is not a network management station information inquiry, the received packet is subjected to the other process according to the type of the received packet (step S 25 ) (subroutine in  FIG. 12 ), followed by terminating the process. 
     When the received packet is a network management station information inquiry in the step S 24 , a response to the inquiry is prepared based on its own network management station identifier and revision number (step S 26 ). The response prepared here may include any information by arrangement between the sender and the receiver. However, an identifier necessary for determining whether or not the sender and the receiver have the same type of network management stations is, at least, needed. According to this embodiment, a constant number is preliminarily decided as a network management station identifier, and the response is prepared in such a way that it may include the constant number and the revision number. Then, the prepared response is transmitted (step S 27 ), followed by terminating the process. 
       FIGS. 8 and 9  are flowcharts showing the procedures for carrying out a process of obtaining a search source list in the network management station  106  or  109 , and the procedures for carrying out a process of searching another network management station on the same network. The program for the processes is stored in a recording medium (ROM  205 , secondary memory  213 ) in the network management station  106  or  109 , and executed by the CPU  203 . 
     In  FIGS. 8 and 9 , first, a first entry in its own managed object node list is spotlighted (step S 31 ).  FIG. 10  is a view showing an example of the managed object node list. The managed object node list  420  is stored in a predetermined area in the RAM  206  or the secondary memory device  213 . The managed object node list  420  registers information such as hardware ID, network address, and type of node. According to this embodiment, the name of a model is simply used as the type of node. However, information on installation of options or the like may be included, if necessary, in addition to the name of a model. 
     A node type of the spotlighted entry is obtained (step S 32 ), thereby making it possible to determine whether or not the node corresponds to the request function of the search source list. In actuality, it is determined whether or not the spotlighted node corresponds to the request function of the search source list (step S 33 ). When the answer to the question of the step S 33  is negative (NO), the process is terminated. 
     On the other hand, when the node spotlighted in the step S 33  corresponds to the request function of the search source list, the search source list request which is to be transmitted to the node is prepared (step S 34 ), and then the search source list request is transmitted (step S 35 ) If the node has no problem, the search source list is to be returned according to the flowchart in  FIG. 6  mentioned above, and so the response is awaited (step S 36 ). 
     It is determined whether or not there is a response (step S 37 ), and then when there is no response, it is determined whether it has become time-out or not (step S 38 ). When it has not become time-out, the process returns to the step S 36 , and the response is awaited again. 
     When it has become time-out, it is determined whether the spotlighted entry is a final entry in the managed object node list (step S 39 ). When it is a final entry, the process is terminated, whereas when it is not a final entry, the next entry in the list is spotlighted (step S 40 ), followed by the process returning to the step S 32 . 
     On the other hand, when there is a response in the step S 37 , a search source list included in the response is obtained (step S 41 ), a first entry in the list is spotlighted (step S 42 ), and a network address is obtained from the entry (step S 43 ). Then, it is inquired via communication whether or not a node in this network corresponds to the network management station which is the same type as its own (step S 44 ). 
     The response is awaited (step S 45 ), and it is determined whether or not there is any response (step S 46 ). When there is no response, it is determined whether or not it has become time-out. When it has not become time-out, the process returns to the step S 45 , the response is awaited again. On the other hand, when it has become time-out, the process proceeds to a step S 50 . 
     On the other hand, when there is a response in the step S 46 , the response is analyzed, and then it is determined whether or not the response shows that a node in the network is the network management station which is the same type as its own (step S 48 ). When the answer to the question of the step S 48  is affirmative (YES), the network address with which communication is made is added to the network address list (network management station list) of the node itself (step S 49 ). The network management station list registers network management stations which are the same type as its own that exist on the same network. 
       FIG. 11  is a view showing a network management station list. In  FIG. 11 , the list  430  registers network addresses, and revision numbers of network management stations which are included in the responses and are at the obtained network addresses. The information to be registered in the list may be any piece of information included in the response inquiring whether or not the network management station is the same type as its own; however, it should include at least the network address. 
     Then, it is determined whether the entry spotlighted at present is a final entry in the search source list (step S 50 ). When it is not a final entry, the spotlight is transferred to the next entry in the search source list (step S 51 ), followed by the process returning to the step S 43 . On the other hand, when it is a final entry, the process returns to the step S 39 . 
       FIG. 12  is a flowchart showing the procedures for carrying out a process of receiving a request for the management object node list  420  as a process according to the other received packet in the step S 25  in  FIG. 7 . 
     First, it is determined whether or not the received packet is a request for the managed object node list or not (step S 61 ). When the received packet is a request for the managed object node list, the managed object node list is read out from a predetermined area in the RAM  206  or the secondary memory device  213  to be stored in another area in the RAM  206 , and further a response to the request for the received managed object node list is prepared (step S 62 ) and then the prepared response is transmitted (step S 63 ), followed by terminating the process. 
     On the other hand, when the packet received in the step S 61  is not a request for the managed node list, a process according to the other received packet is carried out (step S 64 ) (subroutine in  FIG. 12 ), followed by terminating the process. 
       FIG. 13  is a flowchart showing the procedures for carrying out a process of receiving a detailed information request for the managed object node as a process according to the other received packet in the step S 64  in  FIG. 12 . In  FIG. 13 , first, it is determined whether or not the received packet is for a detailed information request for the managed object node (step S 71 ). 
     When the received packet is for the detailed information request for the managed object node, a first entry in the managed object node list  420  stored in the RAM  206  or the secondary memory device  213  is spotlighted (step S 72 ). Then, it is determined whether or not a hardware ID of the spotlighted entry is identical with the one that is designated in the packet for the detailed information request for the managed object node (step S 73 ). Moreover, information to designate a node used in the packet for the detailed information request for the managed object node does not have to be a hardware ID, but may be any information that can define the node uniquely. For example, it may be a network address. 
     When the hardware ID is determined to be not identical in the step S 73 , it is determined whether or not the spotlighted entry is the final entry in the managed object node list (step S 74 ). When the spotlighted entry is not the final entry in the managed object node list, the spotlight is transferred to the next entry in the managed object node list (step S 75 ), followed by terminating the process returning to the step S 73 . 
     When the spotlighted entry is the final entry in the step S 74 , a response showing that the managed object node list does not include a node designated by the detailed information request for the managed object node is prepared (step S 76 ), followed by the process proceeding to a step S 79 . 
     When the hardware ID of the entry spotlighted in the step S 73  is identical with the one that is designated in the packet for the detailed information request for the managed object node, the detailed information of the spotlighted managed object node is read into the RAM  206  (step S 77 ), a response is prepared from the read detailed information (step S 78 ), and then the response prepared in the step S 76  or step S 78  is transmitted (step S 79 ), followed by terminating the process. 
     When the received packet is not for a detailed information request for the managed object node, the received packet is subjected to the other process according to the type of the received packets (step S 80 ), followed by terminating the process. 
       FIGS. 14 and 15  are flowcharts showing the procedures for carrying out a process of collecting information on the managed object nodes in the network management station  106  or  109 . The program for the process is stored in the recording medium (ROM  205 , secondary memory device  213 ), and executed by the CPU  203 . 
     In  FIG. 14 , first, a first entry in the managed object node list is spotlighted (step S 91 ), and then a first entry in a list of the network management stations which are on the network and the same type as its own is spotlighted (step S 92 ). 
     Then, it is determined whether or not the spotlighted managed object node and the spotlighted network management station belong to the same subnet (step S 93 ). When they belong to the subnet, a detailed information request of the spotlighted managed object node is prepared for the spotlighted network management station (step S 94 ), and then the prepared detailed information request is transmitted (step S 95 ). Then, the response is awaited (step S 96 ). 
     Next, it is determined whether or not there is a response to the detailed information request (step S 97 ). When there is no response, it is determined whether it has become time-out or not (step S 98 ). When it does not become time-out, the process returns to the step S 96 , and the response is further awaited. On the other hand, when it has become time-out, the process proceeds to the step S 102 . 
     When there is a response in the step S 97 , it is determined whether or not the response includes the requested detailed information (step S 99 ). When the response includes the requested detailed information, the detailed information is obtained from the response (step S 100 ), and then information on the managed object node list is updated based on the obtained detailed information (step S 101 ), followed by the process proceeding to the step S 111 . 
     When the response does not include the detailed information in the step S 97 , or it has become time-out in the step S 98 , it is determined whether or not the spotlighted network management station is the final entry (step S 102 ). When it is not the final entry, the spotlight is transferred to the next entry in the network management station (step S 103 ), followed by the process returning to the step S 93 . 
     When the network management station spotlighted in the step S 102  is the final entry, the direct communication is made to the spotlighted managed object node to obtain the detailed information (step S 104 ). Then, the response is awaited (step S 105 ), and it is determined whether or not there is received a response (step S 106 ). 
     When there is not received a response, it is determined whether or not it has become time-out (step S 107 ). When it does not become time-out, the process returns to the step S 105 , whereas it has become time-out, the process proceeds to the step S 111 . In this case, the information on the managed object node is not obtained, and the information on the managed object node list is not updated either. 
     When the response is received in the step S 106 , it is determined whether or not the response includes the requested detailed information (step S 108 ). When the response includes the request detailed information, the detailed information included in the response is obtained (step S 109 ), and then the information on the managed object node list is updated based on the obtained detailed information, followed by the process proceeding to the step S 111 . 
     When the response does not include the requested detailed information in the step S 108 , the process proceeds to the step S 111 . In this case, the information on the managed object node is not obtained, and the information on the managed object node list is not updated either. 
     Meanwhile, when the information is updated in the S 101 , the information is updated in the step  110 , it has become time-out in the step S 107 , or the response does not include the requested detailed information in the step S 108 , the process proceeds to the step S 111 . At this stage, the information of the spotlighted managed object node is already obtained and updated, or it has become definite that the detailed information is not obtained. 
     Then, it is determined whether the spotlighted managed object node is the final entry in the list (step S 111 ). When it is the final entry, the process is terminated, whereas when it is not the final entry, the spotlight is transferred to the next entry in the managed object node list (step S 112 ), followed by the process returning to the step S 92 . 
       FIG. 16  is a view showing the flow of the entire process in the network management system. In this context, the network management station A or B corresponds to the network management station  106  or  109 , respectively. Furthermore, the managed object node A is in the same network segment as the network management station A, and corresponds to any one of the MFPs  104 ,  105 , and  107 . Likewise, the managed object node B is in the same network segment as the network management station B, and corresponds to any one of the MFPs  110  and  111 . 
     First of all, the network management station A searches the managed object node (T 1 ). This search is an operation to find out the managed object node in the entire network system. When any one of the managed object node A or the managed object node B responds to the search, both nodes are registered in the managed object node list of the network management station A. 
     The network management station A sends a search source list request to the management node A (T 2 ). Meanwhile, it is supposed to be apparent at the time of the search (see T 1 ) that the managed object node A corresponds to a function of the search source list request. Because the managed object node A has been searched by the network management station B, it has accumulated the information, and the information is communicated to the network management station A. 
     When the network management station A receives the information, it sends an identification inquiry of the network management station to the network management station B (T 3 ). On the other hand, the network management station B has a function of identification inquiry, and sends back its own identifier and revision number. Thereby, the network management station A becomes aware that the network management station B is the same type of network management station as the network management station A. 
     At this moment, the network station A becomes aware that the managed object nodes A and B, and the network management station B exist, and further, it becomes aware from the network address that the managed object node B and the network management station B belong to the same subnet. Furthermore, it also becomes aware that the managed object A belongs to a different subnet from that of the network management station B. 
     Therefore, the network management station A sends, at the stage of obtaining the detailed information on the following respective managed object nodes, the detailed information request directly to the managed object mode A, and obtains the detailed information therefrom (T 4 ). On the other hand, the network management station A requests the detailed information on the managed object node B to the network management station B (T 5 ), and obtains the detailed information therefrom. 
       FIG. 17  is a view showing the flow of the other entire process in the network management system. The network managed stations A and B, and the managed object nodes are the same as those in  FIG. 16 . 
     First of all, the network management station A searches for the management object node (T 11 ). In this context, it is supposed that the search unit used by the network management station cannot reach the managed object node B of the subnet which has a different search manner. Therefore, it is supposed that the response is transmitted to the network management station only from the managed object node A. At this moment, the network management station A does not recognize that the management object node B does not exist. 
     The network management station A sends the search source list request to the management object node A, and obtains the search source list (T 12 ). Because the management object node A has been searched for by the network management station B, the network address of the network management station B is registered in the search source list. 
     The network management station A sends an inquiry for identification of the network management station to the network management station B based on the network address (T 13 ). 
     After the network management station A becomes aware that the network management station B is the same type of network management station, it requests the managed object node list (T 14 ). The managed object node B is registered in the managed object node list included in the response. 
     The network management station A directly sends the detailed information request to the managed object node A whose existence is apparent to obtain the detailed information (T 15 ), whereas it requests the detailed information of the managed object node B to the network management station B to obtain the detailed information (T 16 ). 
     In  FIG. 17 , the managed object node B is not reached by the search unit of the network management station A, and is supposed to be connected to a position whose network cost is so high that the direct communication is impossible. Even in such a case, the network management station A can make the managed object node B a managed object by requesting the detailed information to the network management station B. Therefore, when such managed nodes as the managed object node B increases in number, it is possible to decrease the management cost of the network by cooperation of the network management station A and the network management station B. 
     Thus, according to the network management system of the first embodiment of the present invention, each of the network management stations can easily find the same type of network management stations as its own that exist on the same network, thereby eliminating the need for using a high network cost search method such as a conventional search method. 
     In this case, at least one of the managed object nodes  104 ,  105 ,  107 ,  110 , and  111  has a function of recording the search source list and a function of responding to the search source list request. Each of the network management station  106  and  109  has a function of requesting the search source list and a function of holding a list of the same type of network management stations as its own that exist on the same network. Furthermore, it has a function of inquiring the type of network management stations and its response function, a function of requesting the managed object node list and its response function, and a function of requesting the detailed information of the managed object node and its response function, and the like. 
     In a situation where there are a plurality of the network management stations, by exchanging the information of the managed object node held by the respective network management, it possible to obtain and manage the information without communicating directly with the managed object node, which realizes the highly efficient network management without increasing the network traffic beyond necessity as a whole network management system. 
     The search source list of  FIG. 5  in each of the MFPs may register time when the search is performed, in addition to the network addresses of the network management station. 
     Each of the network management station may transmit the managed object node list managed by the network management station itself to another network management station. The network management station that receives the managed object node list from another network management station may work out and manage a list of sum of sets with its own managed object node list. 
     As for each entry in the managed object node list in  FIG. 10 , each of the network management station may manage information showing the hop count in the case of communication with the managed object node. In this context, the hop count is information showing how many routers are traversed in order to communicate with an object device. The information is also transmitted when the managed object node list is transmitted to another network management station. 
     As for each entry in the managed object node list in  FIG. 10 , each of the network management station determines which gives lower load to the network for the network management station itself to manage the managed object node through direct network communication, or for the same type of another network management station to manage through communication. When it is determined to give lower load to the network for the network management station itself to manage the managed object node through direct network communication, information indicating it is added to the entry in the managed object node list. On the other hand, when it is determined to give lower load to the network for the same type of another network management station to manage through communication, information indicating it is added to the entry in the managed object node list. When the managed object node list is transmitted to another network management stations, the above information may be transmitted simultaneously. 
     The network management system according to a second embodiment of the present invention will be described below. 
     According to the first embodiment of the present invention, when the managed object node receives a packet determined to be a search packet, it adds the transmitter of the packet to the search source list unconditionally. On the contrary, according to the second embodiment of the present invention, when the managed object node adds the transmitter to the managed object node, it verifies a hardware ID of the transmitter. 
     The construction of the network management system according to the second embodiment is identical with that of the network management system according to the first embodiment; therefore, the identical reference numerals are used for corresponding elements and parts and hence the description thereof is omitted. The internal construction of the network management station and the internal construction of the managed object node, namely the MFP are identical with those of the first embodiment; therefore, the identical reference numerals are used for corresponding elements and parts and hence the description thereof is omitted. 
       FIG. 18  is a flowchart showing the procedures for carrying out a process of receiving the search packet in the network controller  303  in the managed object node, namely the MFP according to the second embodiment of the present invention. The program for the process is stored in the ROM  307 , and executed by the CPU  305 . 
     In  FIG. 18 , first of all, it is checked whether there is any received packet or not (step S 121 ). As a result of the check, it is determined whether there is any received packet or not (step S 122 ). When there is no received packet, the process returns to the step S 121 , whereas when there is a received packet, the received packet is read into the RAM  308  (step S 123 ). 
     Then, it is determined whether the received packet is a search packet or not (step S 124 ). When the received packet is not a search packet, the received packet is subjected to the other process according to the type of the received packet (step S 134 ), followed by terminating the process. 
     On the other hand, when the received packet is a search packet, a response to the search packet is prepared (step S 125 ), and the prepared response is transmitted (step S 126 ). 
     Thereafter, a hardware ID of the transmitter is obtained from the received search packet (step S 127 ), the first entry in the search source list held by itself is spotlighted (step S 128 ), and then it is determined whether or not the hardware ID of the spotlighted entry in the search source list agrees with the hardware ID of the search source obtained in the step S 127  (step S 129 ). 
     When it does not agree, it is determined whether or not the spotlighted entry in the search source list is a final entry in the search source list (step S 130 ). When it is not a final entry, the spotlight is transferred to the next entry in the search source list (step S 131 ), followed by the process returning to the step S 129 . 
     In the question of the step S 129 , when the hardware ID of the spotlighted entry in the search source list agrees with the hardware ID of the search source in the search packet, the spotlighted entry is deleted from the search source list (step S 132 ), and then the hardware ID and the network address of the transmitter of the received search packet are additionally added to the search source list (step S 133 ), followed by terminating the process. 
     In the question of the step S 130 , when the spotlighted entry in the search source list is a final entry in the search source list, the process of the step S 133  is carried out likewise. 
       FIG. 19  is a table showing an example of the search source list held by the managed object node. The search source list  510  registers network addresses and hardware IDs with which the managed object nodes (MFPs) have received search packets from the search source so far. Specifically, the registered hardware IDs are comprised of “0XXX0DF080B73, 0YXY390CF0991, 0ZYX6FA10BB96, etc.” and the registered network addresses “are comprised of 172.xx.yy.zz, 172.aa.bb.cc, 172.rr.ss.tt, etc.”. 
     The other processes in the network management system according to the second embodiment are the same as those according to the first embodiment. Namely, the process of the managed object node receiving the search source list request is the same as the process shown in  FIG. 6 . The process of the network management station responding to the network management station inquiry is the same as the process shown in  FIG. 7 . The process of the network management station finding another network management station is the same as the process shown in  FIGS. 8 and 9 . The managed object node list held by the network management station is the same as the list shown in  FIG. 10 . The list of the same type of the network management station as its own that exists on the network is the list shown in  FIG. 11 . The process of receiving the managed object node list request is the same as the process shown in  FIG. 12 . The process of receiving the detailed information request of the managed object node is the same as the process shown in  FIG. 13 . The process of the network management station collecting the information of the managed object node is the same as the process shown in  FIGS. 14 and 15 . The flows of the entire process in the network management system are the same as those which are shown in  FIGS. 16 and 17 . 
     According to the network management system of the second embodiment, verifying the hardware ID of the transmitter prevents the same transmitters from being doubly registered in the search source list. As a result, when carrying out the process of inquiring about the existence of the network management station (see  FIG. 8  and  FIG. 9 ), it is possible to decrease the probability of making a plurality of inquiries to the same network management station, thereby decreasing the network traffic compared with the first embodiment to increase the management efficiency. 
     A network management system according to a third embodiment will be described below. 
     According to the second embodiment, verifying the hardware ID of the transmitter prevents the same transmitter from being doubly registered in the search source list. The network management system according to the third embodiment is characterized by registering the transmitters, which are different in search manner from one another, separately in the search source list. 
     The construction of the network management system according to the third embodiment is identical with that of the network management system according to the first embodiment; therefore, the identical reference numerals are used for corresponding elements and parts and hence the description thereof is omitted. The internal construction of the network management station and the internal construction of the managed object node, namely the MFP are identical with those of the first embodiment; therefore, the identical reference numerals are used for corresponding elements and parts and hence the description thereof is omitted. 
       FIGS. 20 and 21  are flowcharts showing the procedures for carrying out a process of receiving the search packet in the network controller  303  in the managed object node, namely the MFP according to the third embodiment of the present invention. The program for the process is stored in the ROM  307  in the network controller  303 , and is executed by the CPU  305 . 
     In  FIG. 20 , first of all, it is checked whether there is any received packet or not (step S 151 ). As a result of the check, it is determined whether there is any received packet or not (step S 152 ). When there is no received packet, the process returns to the step S 151 , whereas when there is a received packet, the received packet is read into the RAM  308  (step S 153 ). 
     Then, it is determined whether the received packet is a search packet or not (step S 154 ). When the received packet is not a search packet, the received packet is subjected to the other process according to the type of the received packet (step S 155 ), followed by terminating the process. 
     On the other hand, when the received packet is a search packet, a response to the search packet is prepared (step S 156 ), and the prepared response is transmitted (step S 157 ). 
     Thereafter, a hardware ID of the transmitter is obtained from the received search packet (step S 158 ), the first entry in the search source list held by itself is spotlighted (step S 159 ), and then it is determined whether or not the hardware ID of the spotlighted entry in the search source list agrees with the hardware ID of the search source obtained in the step S 127  (step S 160 ). 
     When it agrees, it is determined whether or not the search manner registered in the spotlighted entry in the search source list agrees with the search manner of the received search packet (step S 161 ). When it agrees, the spotlighted entry is deleted from the search source list (step S 162 ). The hardware ID, the network address, and the search manner of the transmitter in the received search packet are added to the search source list (step S 163 ), followed by terminating the process. 
     On the other hand, when the hardware ID does not agree in the step S 160 , or the search manner does not agree in the step S 161 , it is determined whether or not the spotlighted entry in the search source list is a final entry in the search source list (step S 164 ). When it is not a final entry, the spotlight is transferred to the next entry in the search source list (step S 165 ), followed by the process returning to the step S 160 . Meanwhile, when it is a final entry, the hardware ID, the network address, and the search manner of the transmitter in the received packet are added to the search source list (step S 166 ), followed by terminating the process. 
       FIG. 22  a table showing an example of the search source list held by the managed object node. The search source list  550  registers network addresses, hardware IDs, and search manners with which the managed object nodes (MFPs) have received the search packets from the search source so far. Specifically, the registered hardware IDs are comprised of “0XXX0DF080B73, 0YXY390CF0991, 0ZYX6FA10BB96, etc.”, the network addresses in response to the hardware IDs are comprised of “172.xx.jj.zz, 172.aa.bb.cc, 172.rr.ss.tt, etc.”, and then the search manners in response to the hardware ID are comprised of “broadcast, unicast, multicast, unicast, broadcast, etc.”. As is distinct from the second embodiment, this search source list includes entries which are different only in a search manner from each other and identical in a hardware ID and a network address with each other, specifically, the hardware ID “0YXY390CF0991” and the network address “172.aa.bb.cc”. 
     In the network management system according to the third embodiment, the same procedures as those of the first embodiment are as follows. Namely, the process of the managed object node receiving the search source list request is the same as the process shown in  FIG. 6 . The process of the network management station responding to the network management station inquiry is the same as the process shown in  FIG. 7 . The process of the network management station finding another network management station is the same as the process shown in  FIGS. 8 and 9 . The managed object node list held by the network management station is the same as the list shown in  FIG. 10 . The list of the same type of the network management station as its own that exists on the network is the list shown in  FIG. 11 . The process of receiving the management object node list request is the same as the process shown in  FIG. 12 . The process of receiving the detailed information request of the management object node is the same as the process shown in  FIG. 13 . The flows of the entire process in the network management system are the same as those which are shown in  FIGS. 16 and 17 . 
       FIGS. 23 ,  24 ,  25  and  26  are flowcharts showing the procedures for carrying out a process of the network management station collecting information on the managed object nodes. The program for the process is stored in recording medium (ROM  205  and secondary memory device  213 ), and is executed by the CPU  203 . 
     In  FIG. 23 , first of all, the first entry in the management object node list is spotlighted (step S 171 ), and then it is determined whether or not the search source list has been ever obtained from the managed object node of the entry spotlighted in the managed object node list (step S 172 ). 
     When the search source list has not been obtained, the process proceeds to the step S 188 , whereas when the search source list has been ever obtained, the first entry in the search source list obtained in the past is spotlighted (step S 173 ). It is determined whether or not the search source recorded in the first entry is listed in the same type of the network management station list as itself held by the network management station (step S 174 ). When it is not listed, the process proceeds to the step S 184 . 
     When it is listed in the network management station list, it is determined whether or not the search manner recorded in the item of search manner in the entry is broadcast (step S 175 ). When the search manner is not broadcast, the process proceeds to the step S 184 , whereas when the search manner is broadcast, a request is prepared to the network management station, namely the search source of the entry (step S 176 ). This request is a detailed information request of the managed object node in the entry spotlighted in the managed object node list. 
     Then, the prepared detailed information request is transmitted (step S 177 ), followed by awaiting the response (step S 178 ), and then it is determined whether there is a response (step S 179 ), and then when there is no response, it has become determined whether it has become time-out or not (step S 180 ). When it has become time-out and a response from the network management station, namely the search source is not received, the process proceeds to the step S 184 , whereas when it has not become time-out, the process returns to the step S 178 . 
     On the other hand, when there is a response in the step S 179 , it is determined whether or not the requested detailed information is included in the received response (step S 181 ). When it is included, the detailed information is obtained from the response (step S 182 ), and then the entry spotlighted in the management object node list, namely the detailed information of the managed object node is updated with the obtained detailed information (step S 183 ). 
     After the detailed information has been updated, it is determined whether or not the entry spotlighted in the management object node list is a final entry (step S 186 ). When it is a final entry, the process is terminated, whereas when it is not a final entry, the spotlight is transferred to the next entry in the managed object node list (step S 187 ), followed by the process returning to the step S 172 . 
     In the question of the step S 181 , when the detailed information is not included, it is determined whether or not the entry spotlighted in the search source node list is a final entry (step S 184 ). When it is not a final entry, the spotlight is transferred to the next entry in the search source node list (step S 185 ), and the process returns to the step S 174 . 
     In the question of the step  184 , when it is a final entry, the first entry in the network management station list is spotlighted (step S 188 ). It is determined whether or not the spotlighted network management station and the spotlighted management object node belong to the same subnet (step S 189 ). 
     When they belong to the same subnet, a detailed information request of the managed object node is prepared for the spotlighted network management station (step S 190 ). The prepared detailed information request is transmitted (step S 191 ). The response is awaited (step S 192 ), and then it is determined whether or not there is a response (step S 193 ). 
     When there is a response, the process proceeds to the step S 195 , whereas when there is no response, it is determined whether or not it has become time-out (step S 194 ). When it has become time-out, the process proceeds to the step S 198 , whereas when it has not become time-out, the process returns to the step S 192 . 
     In the question of the step S 193 , when there is a response, it is determined whether or not the requested detailed information is included in the obtained response (step S 195 ). When the detailed information is not included, the process proceeds to the step S 198 , whereas when the detailed information is included, the detailed information included in the response is obtained (step S 196 ), and then the information of the managed object node list is updated with the obtained detailed information (step S 197 ), followed by the process returning to the step S 186 . 
     When they do not belong to the same subnet in the step S 189 , it has become time-out in the step S 194 , or the detailed information is not included in the step S 195 , the process proceeds to the step  198 . Then, it is determined whether or not the spotlighted network management station is a final entry in the network management station list (step S 198 ). When it is not a final entry, the spotlight is transferred to the next entry in the network management station list (step S 199 ), the process returns to the step S 189 . 
     When it is a final entry, direct network connection is performed to the spotlighted management object node, and an inquiry is made to acquire the detailed information (step S 200 ), followed by awaiting the response (step S 201 ), and then it is determined whether or not there is a response (step S 202 ). 
     When there is no response, it is determined whether or not it has become time-out (step S 203 ). When it has become time-out, the process returns to the step S 186 , whereas when it has not become time-out, the process returns to the step S 201 . 
     When there is a response in the step S 202 , it is determined whether or not the requested detailed information is included in the response (step S 204 ), and then when it is not included, the process returns to the step S 186 . 
     When the requested detailed information is included, the detailed information included in the response is taken out (step S 205 ), and then the detailed information of the spotlighted management node in the managed object node list is updated (step S 206 ), followed by the process returning to the step S 186 . 
     According to the network management system of the third embodiment, the network management station can recognize an access manner to the managed object node by recording the search manner in the search source list. For example, a method of obtaining the detailed information through the network management station capable of accessing the managed object node by broadcast, and a method of obtaining the detailed information by direct connection to the management object node are compared. When the method of obtaining the detailed information through the network management station which is located comparatively near on the network needs lower cost than that of obtaining it by direct connection to the managed object node, the former method can be surely chosen. 
     It should be noted that the present invention is not limited to the construction of the above-described embodiments, but any construction capable of achieving the functions described in the claims or the functions included in the construction of the embodiments is applicable. 
     For example, the managed object node is not limited to the MFP, but any scanners, printers, copiers, facsimiles are included. 
     It is to be understood that the object of the present invention may also be accomplished by supplying a system or an apparatus with a storage medium in which a program code of software which realizes the functions of the above described embodiment is stored, and causing a computer (or CPU or MPU) of the system or apparatus to read out and execute the program code stored in the storage medium. 
     In this case, the program code itself read from the storage medium realizes the functions of any of the embodiments described above, and hence the program code and the storage medium in which the program code is stored constitute the present invention. 
     Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magnetic-optical disk, a CD-ROM, a CD-R, a CD-RW, DVD-ROM, a DVD-RAM, a DVD-RW, a DVD+RW, a magnetic tape, a nonvolatile memory card, and a ROM. Alternatively, the program may be downloaded via a network. 
     Further, it is to be understood that the functions of the above described embodiment may be accomplished not only by executing a program code read out by a computer, but also by causing an OS (operating system) or the like which operates on the computer to perform a part or all of the actual operations based on instructions of the program code. 
     Further, it is to be understood that the functions of the above described embodiment may be accomplished by writing a program code read out from the storage medium into a memory provided on an expansion board inserted into a computer or in an expansion unit connected to the computer and then causing a CPU or the like provided in the expansion board or the expansion unit to perform a part or all of the actual operations based on instructions of the program code. 
     The above-described embodiments are merely exemplary of the present invention, and are not be construed to limit the scope of the present invention. 
     The scope of the present invention is defined by the scope of the appended claims, and is not limited to only the specific description in this specification. Furthermore, all modifications and changes belonging to equivalents of the claims are considered to fall within the scope of the present invention. 
     This application claims the benefit of Japanese Patent Application No. 2006-045503 filed Feb. 22, 2006, which is hereby incorporated by reference herein in its entirety.