JPH0851453A - Network equipment, method for detecting network equipment and method for recognizing constitution of network - Google Patents

Abstract

PURPOSE:To efficiently recognize nodes existing in a network and the constitution of the network by providing this network system with a means for periodically transmitting a frame after receiving a retrieving frame and a means for transmitting the retrieving frame from a specified interface. CONSTITUTION:The network system is provided with the trap transmitting means 105 for periodically transmitting a frame to a management device after receiving a retrieving trap and the retrieving frame transmitting means 106 for transmitting a retrieving frame from a specified interface. When the managing device sends the retrieving frame by multi-cast transmission, all network terminals connected to the same segment as the managing device receive the retrieving frame and then transmit the frame to the managing device. When the managing device sends the retrieving frame by multi-cast transmission from a specified interface to network terminals, all network terminals connected to the interface receive the retrieving frame, and then transmit the frame to the managing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network device such as a concentrator or a relay device connected to a network, a network device detection method for detecting the network device, and a network configuration recognition method for recognizing the network configuration.

[0002]

2. Description of the Related Art TCP / IP (Transmission Control P
Two types of addresses, an IP address and a physical address, are assigned to devices such as network devices and computers that exist in an rtocol / Internet Protocol) network. The network device temporarily stores a combination of an IP address and a physical address of another device existing in the network.

Conventionally, there has been known a method of detecting a device existing in a network by obtaining address information stored in another device from a management device by using a network management protocol (Japanese Patent Laid-Open No. Hei. 229742
issue).

In addition, a multi-port relay device generally called a hub (HUB) is provided with means for storing the address of the device connected to each port, so that the configuration of a star network in which hubs are cascade-connected is managed by a management device. Is known (Japanese Patent Laid-Open No. 5-175).
965).

[0005]

Since the address information stored in each device does not include the information of all the devices existing in the network, it is not always possible to detect all the devices. Further, since address information is generally deleted regularly, it may take time to detect many devices.

Further, the network is composed of not only hubs but also network devices such as bridges and routers, and the network manager is required to always know how these network devices are connected. .

However, recent computer networks are often constructed by laying cables under the floor over a plurality of floors in a building, and it is necessary to trace the cables to find out how the network devices are connected. Is extremely difficult.

Therefore, an object of the present invention is to solve the above problems and provide a network device, a network device detecting method and a network structure recognizing method capable of efficiently recognizing the nodes existing in the network and the structure of the network. Especially.

[0009]

In order to achieve the above object, the present invention provides a network device such as a concentrator and a relay device, which is connected to a network such as a local area network, to a management device after receiving a search frame. It is provided with a frame transmitting means for periodically transmitting a frame and a search frame transmitting means for transmitting a search frame from a designated interface.

In order to achieve the above object, the present invention provides a network device detecting method for detecting network devices such as a concentrator and a relay device connected to a network such as a local area network, wherein a management device multicasts a search frame. The network device that has transmitted and received the search frame periodically transmits the frame to the management device after receiving the search frame, so that the management device detects the network device.

In order to achieve the above object, the present invention provides a method for detecting a network device such as a concentrator and a relay device connected to a network such as a local area network, in which a management device notifies a network device. Connected to the segment to which the management device is connected via the network device by sending the search frame by multicast from the specified interface and the network device receiving the frame periodically sends the frame to the management device after receiving the frame. The management device detects the network device that has been set.

In order to achieve the above object, the present invention provides a network configuration recognition method for recognizing the configuration of a network such as a local area network, in which the management device multicasts a search frame and receives the search frame. After receiving the search frame for each segment, the frame is periodically transmitted to the management device to recognize the network configuration.

In order to achieve the above object, the present invention is a network configuration recognition method for recognizing a network configuration such as a local area network, in which multicast is performed from an interface in which a management device specifies a search frame to a network device for each segment. Let me send
The network device that receives the frame recognizes the network configuration by periodically transmitting the frame to the management device after receiving the frame.

To achieve the above object, the present invention detects a node existing in a network by a management station broadcasting a response request frame, and a relay device determines which interface another node is connected to. Other nodes detected by determining which interface of the relay device the management station is connected to by using the storing function, and temporarily stopping the frame relay function of each interface of the relay device by the management station. Is to determine which interface of the relay device is connected.

[0015]

According to the above configuration, when the management device multicasts the search frame, all network devices connected to the same segment as the management device receive the search frame, and then transmit the frame to the management device. A network device connected to the same segment as the management device can be detected without omission.

When the management device causes the network device to multicast the search frame from the designated interface, all the network devices connected to the segment to which the interface is connected receive the search frame, and after receiving the management, Since the frame is transmitted to the device, the management device can detect the network device connected to the segment indirectly connected through the network device without omission.

In addition to the above configuration, the network configuration can be recognized by detecting the network device for each segment.

Further, according to the above, the node existing in the network is detected by broadcasting the response request frame. By acquiring the number of detected interfaces of each node by using the network management protocol, it can be determined whether or not the node is a relay device. The number of interfaces of the relay device is acquired by using the network management protocol. By transmitting a frame from the management station to the relay device, the interface to which the management station is connected is stored in the relay device, and then the information is obtained from the management station using the network management protocol. To be done.

Among the plurality of interfaces of the relay device, the frame relay function of the interface on the side to which the management station is connected is temporarily stopped, and then the management station transmits a response request frame indicating the reachability of other nodes. It is possible to determine whether the node is on the front side or the other side of the relay device as seen from the management station.

Among the plurality of interfaces of the relay device, the frame relay function of the interface other than the interface to which the management station is connected is temporarily stopped, and then the response request frame is transmitted from the management station to the other nodes. By checking reachability, it can be determined whether or not the node is connected to the interface side.

Therefore, all the nodes that can respond to the response request frame can be detected in a short time without omission. Further, there is no need to have any node in the network that can respond to the reference request for the address correspondence table. In addition, it is possible to automatically and accurately recognize the configuration of the network connected by the relay device having the relay determination function.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Although the present invention is a method widely applicable to all computer networks, TCP / IP is used as a protocol corresponding to the third and fourth layers of the OSI reference model.
SNMP (Simp
le Network Management Protocol) is most preferably applied to a local area network. An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of an embodiment of the network device of the present invention.

As shown in the figure, the network device 10
1, a CPU (central processing unit) 102, a non-volatile memory 103, a bus 104, a trap transmission means 105,
Search frame transmitting means 106 and SNMP communication means 1
07 is stored in the main storage device 108, and has an SNMP agent function.

The trap transmission means 105, the search frame transmission means 106 and the SNMP communication means 107 are loaded into the main memory 108 and executed by the CPU 102. Trap transmission means 105 and search frame transmission means 106
Exchange frames using the SNMP communication means 107. The network device 101 has a management item (hereinafter referred to as “trap flag”) for setting whether or not to send a trap frame to the management device.

The value of the trap flag is initialized to a value (hereinafter referred to as "False") that does not send a trap when the power of the network device is turned on or reset. The network device 101 sets the trap flag to "True".
If it is set to (value to send trap), then "F
The trap frame is periodically transmitted to the management apparatus until it is set to "alse". The trap flag is "Fals
If it is "e", the trap frame is not transmitted. By providing the trap flag in the network device, the management device can cause the network device to transmit the trap frame only when necessary.

Further, the network device has a management item (hereinafter referred to as "search flag") for transmitting a frame when a value is set. When the search flag is set to a value for identifying the interface of the network device 101, only the network device 101 sets the destination address of a frame in which the trap flag is set to “True” (hereinafter referred to as “search frame”). The multicast address to be received is sent from the interface corresponding to the value specified in the search flag.

FIG. 2 is a block diagram of the network management apparatus of the present invention.

As shown in the figure, the network management device 201 comprises a CPU 205, a bus 206, and a main storage device 209 comprising an automatic recognition means 207 and an SNMP communication means 208, and has an SNMP manager function. are doing. The network management device 201 is connected to the input device 202, the output device 203, and the storage device 204.

The automatic recognition means 207 and the SNMP communication means 208 are loaded into the main storage device 209, and the CPU 20
Run with 5. The automatic recognition means 207 exchanges frames using the SNMP communication means 208. The recognized network configuration diagram is displayed to the administrator by the output device 203. The network configuration information acquired through automatic recognition is stored in the storage device 204.

FIG. 3 is a network configuration management table created by the automatic recognition means shown in FIG.

A number assigned to the detected network device is set in 301. Reference numeral 302 denotes the number of a network device or management device (hereinafter referred to as “seed device”) that has transmitted the search frame to the own network device (hereinafter referred to as “seed number”) 303. A management information value (hereinafter referred to as "ifIndex") for identifying the transmitted interface is set. 304 is the IP of the network device
An address is 305, a management information value for identifying the system (hereinafter referred to as “sysDescr”), and a management information value for the number of interfaces are indicated at 306 (hereinafter “ifNum”).
"ber". ) Is set. 307, 308, 30
In 9, information for each interface is set. The interface “ifIndex” is set in 307. 30
A management information value (hereinafter referred to as “ifType”) indicating the interface type is set in 8. In 309, a number for identifying the segment to which the interface is directly connected is set. By setting the above-mentioned information in this configuration management table and storing it in the storage device 204 (see FIG. 2) of the management device, even if the power of the management device is turned off after the automatic recognition means has been executed once. By referring to the configuration management table, the network configuration diagram can be displayed again.

FIG. 4 is a flow chart of processing for detecting a network device provided in the management device shown in FIG. 2 and in the same segment as the management device.

In the figure, first, the management device multicasts a search frame and sets a timeout (step 401). When a search frame is transmitted by multicast, all network devices connected to the same segment as the management device receive the above frame, the trap flag is set to "True", and then a trap frame is periodically transmitted to the management device. To do. When the management device receives the trap frame, it assigns an unused number to the network device that sent it and registers it in the configuration management table, and the seed device and the seed “ifInde”.
x "is set (step 404). Then, the trap flag of the network device is set to “False”,
Stop transmission of trap frame (step 40)
5).

The same processing is performed when a trap frame is received from another network device. When the time is out, the process ends (step 402). Through the above exchanges, the management device detects all the network devices set in the same segment as its own device.

FIG. 5 is a flow chart of a process for acquiring detailed information of the network device detected by the management device shown in FIG.

In the figure, first, the detected "sysDescr" and "ifNumber" of the network device are detected.
“R” is acquired and set in the “sysDescr” and “ifNumber” fields of the configuration management table (step 50).
2, 503).

Next, for each interface, "ifType
e ”is acquired (step 504). As a result, the LAN type of the segment connected to each interface of the detected network device can be known.

Next, a number is assigned to the segment connected to each interface (step 505). At this time, of the plurality of segments to which the network device is connected, a number has already been assigned to the segment on the management device side, so the same number as that, that is, the segment number corresponding to the seed “ifIndex” of the seed device is set. Set. Assign unused numbers to the segments connected to other interfaces. The above processing is repeated for other detected network devices.

FIG. 6 is a flow chart of a process in which the management device shown in FIG. 2 detects a network device connected to a segment indirectly connected via the network device.

In the figure, first, a value for identifying an interface is set in the search flag of the network device detected by the management device, and a timeout timer is set (step 602). The network device having the value set in the search flag multicasts the search frame from the interface corresponding to the specified value. When multicast transmission is performed, all network devices connected to the segment to which the interface is connected receive the frame, the trap flag is set to "True", and then the trap frame is periodically transmitted to the management device.

When the management device receives the trap frame, it assigns an unused number to the network device that has transmitted it and registers it in the configuration management table, and the seed device and the seed “ifIndex” column indicate the network device number and “ifIndex”. Is set (step 60)
5). Then, the trap flag of the network device that transmitted the trap frame is set to "False", and the transmission of the trap frame is stopped (step 606).

The same processing is performed when a trap frame is received from another network device. When the time is out, the process ends (step 603). Other "ifInde
Similar processing is performed for "x" (step 601).

Through the above exchange, the management device detects all network devices connected to the segment to which the interface specified by the detected network device is connected. The management device detects all the network devices existing in the network by performing the above process for all interfaces of the detected network device.

FIG. 7 is a flow chart of the entire automatic recognition means shown in FIG.

In the figure, first, the management device searches for a segment directly connected (step 701), and acquires detailed information about the detected relay device (step 702).

Next, a search frame is transmitted to the detected network device (step 704), and detailed information about the newly detected network device is acquired (step 705). Similar processing is performed for the other detected network devices (step 703).

FIG. 8 is an example of a network composed of a plurality of network devices. FIG. 9 is a network configuration diagram recognized by the management device after performing the processing shown in FIGS. 3 and 4 on the network of FIG.

The management device 901 performs the processing shown in FIG. 3 to detect the network devices 903 and 907 existing in the segment 902 to which the management device 901 is directly connected.
Next, the processing shown in FIG. 4 is performed on the detected network device to obtain the number of interfaces of each network device.

FIG. 10 shows a network configuration diagram recognized by the management apparatus after performing the processing shown in FIGS. 5 and 4 on the network apparatus 907 shown in FIG. The management device performs the processing shown in FIG. 5, and the network device 1 existing in the segment 1001 to which the management device is not directly connected
002 and 1005 are detected. Next, the processing shown in FIG. 4 is performed on the detected network device to obtain the number of interfaces of each network device.

FIG. 11 shows another network configuration diagram that the management apparatus recognizes after performing the processing shown in FIGS. 5 and 4 on the network apparatus 903 shown in FIG. The management device performs the processing shown in FIG. 5 to detect the network device 1102 existing in the segment 1101 to which the management device is not directly connected. Next, the detected network device is subjected to the processing shown in FIG.
Get the number of interfaces such as 2.

FIG. 12 shows a network configuration diagram recognized by the management apparatus after the automatic recognition processing. The management device detects the network devices existing in the actual network shown in FIG. 8 and recognizes how they are connected. This figure is also an example of the network configuration screen display at this stage.

As described above, according to this embodiment, by using the network device and the network device detecting method, it is possible to efficiently detect all the network devices connected to the network. Further, by using the above network configuration recognition method, it is possible to recognize how the network devices are connected.

FIG. 13 is a diagram showing an example of networks connected by a relay device to which the network configuration recognition method of the present invention is applied.

In the figure, 1100 is a network management station, 1200 is a bridge having three interfaces, 13 is a bridge having two interfaces, 1400 is a computer, and 1500 is a transmission medium.

FIG. 14 is a hardware block diagram of a network management station including the automatic recognition unit shown in FIG. 15 according to the present invention.

In the figure, 2100 is a management station main body, 2200 is a CPU, 2300 is a system bus, 2
Reference numeral 400 denotes a display for displaying an automatically recognized network configuration diagram, 2600 is a keyboard, 2700 is a LAN adapter for controlling frame transmission / reception, and 2800 is a secondary storage device for storing information for realizing an automatic recognition means. The secondary storage device 28 also stores network configuration information collected by the automatic recognition means.

FIG. 15 shows the software configuration of the management station shown in FIG.

In the figure, 3100 is an emission storage device, 3
200 is an automatic recognition unit, 3300 is an SNMP unit, 3400
Is a TCP / IP unit, 3500 is an OS (operating system), 3600 is a configuration database (secondary storage device). The automatic recognition unit 3200 is the SNMP unit 3300.
Frames are exchanged using the function of the TCP / IP unit 3400. The collected network configuration information is made into a database and stored in the secondary storage device.

FIG. 16 is a flow chart of a process for the network management station shown in FIG. 13 to detect a node existing in the network.

The management station broadcasts a response request frame (step 4100).

In the TCP / IP network, ICMP echo reply and UDP are used as response request protocols.
(User Datagram Protocol) echo etc. can be used. When the response frame is received, the source address is registered in the database (step 4300).

When no response comes, the process ends.

FIG. 17 is a flow chart of processing for determining whether or not the node detected by the network management station shown in FIG. 13 is a bridge.

First, the number of interfaces of a node is acquired by using the SNMP GET operation (step 510).
0).

It is determined whether there are two or more interfaces other than the loopback interface (step 5200). If there are two or more interfaces, the node is determined to be a bridge (step 530).
0). If there is only one interface, then the node is determined not to be a bridge (step 5400).
If determined, the type is entered in the database (step 5500). If there is a node that has not been determined yet, the above processing is repeated (step 5600).

FIG. 18 is a flow chart of a process for the network management station shown in FIG. 13 to determine which interface side the management station is connected to among the plurality of interfaces that the bridge has.

First, the management station to be judged transmits a response request frame to the bridge to be judged (step 6100). This allows the bridge to remember which interface the management station is connected to.
Then, the interface number to which the management station is connected is obtained by checking which interface the address of the management station is stored using SNMP (step 6200). If there is a bridge that has not been processed yet, the above process is repeated (step 6).
300).

FIG. 21 is a network configuration diagram recognized by the management station after performing the processing shown in FIG.

This figure is also an example of a network configuration diagram screen display at this stage.

Thus, the progress of the automatic recognition processing can be notified to the administrator by displaying the network configuration diagram even during the processing. At this stage, all the detected nodes are connected to the same segment 1 (9100). Here, 9200 and 9300 are bridge A interfaces, 9500 and 9600 are bridge B interfaces, and 9700 and 9800 are bridge C interfaces.

FIG. 19 is a flow chart of a process for judging whether the node detected by the network management station shown in FIG. 13 is at the tip of the bridge as seen from the management station. First, of the plurality of interfaces of the bridge, the frame relay function of the interface to which the management station is connected is disabled using SNMP (step 7100). In this state, a response request frame is transmitted to check the reachability of the node to be determined (step 7200). If no response frame is returned, then the node is determined to be beyond the bridge as seen by the management station (step 7400). If a response frame is received, then it is determined that the node is not beyond the bridge as seen by the management station (step 7500).
If there is a node that has not been determined yet, the above processing is repeated (step 7600).

FIG. 22 is a network configuration diagram recognized by the management station after performing the process shown in FIG. 21 on the bridge A. Since the bridge C and the computers c to j can be determined to be at the end of the bridge A from the viewpoint of the management station, they are connected to an interface other than the interface to which the management station is connected. However, the bridge A has two interfaces in addition to the interface on the management station side. At this stage, since it is not yet determined which interface each node is ahead of, the node is connected to two segments 2, 3 (10200). Further, since it is determined that the bridge B and the computers a to h are not ahead of the bridge A from the viewpoint of the management station, the interface of the bridge A is assigned to the segment 1 (10100) to which the management station is connected. Stay connected.

FIG. 23 is a network configuration diagram recognized by the management station after the bridge B is also subjected to the same processing as that shown in FIG. Computer g
Since the computer h can be determined to be at the end of the bridge B from the viewpoint of the management station, the computer h is connected to the end of the interface of the bridge B which is not the interface to which the management station is connected. Since the bridge B has only two interfaces, the interface to which the computer g and the computer h are connected can be specified at this stage. Therefore, computer g and computer h
Is connected to segment 4 (11300).

Further, since it can be determined that the computer a and the computer b are not ahead of the bridge B from the viewpoint of the management station, they remain connected to the segment 1 (11100) to which the management station is connected.

FIG. 20 is a flow chart of a process for determining which interface of the bridge the node, which is determined to be at the bridge end as viewed from the management station, is connected to.

First, among the interfaces of the bridge, the frame relay function of the interface other than the interface on the management station side is disabled (step 810).
0). In this state, a response request frame is transmitted to check the reachability of the node to be determined (step 820).
0). If no response frame is returned, then the node is determined to be beyond the interface (step 8400). If a response frame is received, then it is determined that the node is not beyond that interface (step 8500). If there is a node that has not been processed yet, the above processing is repeated (step 860).
0). Even if there are no unprocessed nodes, if there is a node whose connection destination is not yet determined, the interface is changed and the above process is repeated. However, the interface on the management station side is excluded.

FIG. 24 is a network configuration diagram recognized by the management station after the bridge A has been subjected to the above-described processing. Since the interface of the bridge A to which the computer j is connected can be determined from the bridge C and the computer c, the segment 2 (12200) and the segment 3 (1230) of the respective interfaces can be determined.
0). Since the segment C has a bridge C that has not been processed yet, the process shown in FIG. 19 is also performed for this. FIG. 25 is a network configuration diagram recognized by the management station after performing the processing.
The node (computer c that was connected to segment 2
From computer j) to computer j), it is possible to determine that computer i and computer j are ahead of bridge C from the viewpoint of the management station.
0). Further, since it can be determined that the computer c and the computer d are not ahead of the bridge C from the viewpoint of the management station, they remain connected to the segment 2 (13200). At this stage, all bridges have already been processed.
A block diagram equivalent to three actual network configurations has been recognized.

FIG. 26 is an example of a database created by an automatic recognition section as an automatic recognition means. 14100 is a node number, 14200 is a node IP address, 143
00 is the physical address of the node, 14400 is the node type, 14500 is the number of node interfaces, 1460
0 is an interface number, and 14700 is a segment number connected to the interface. By recording all network configuration information in this database, even if the automatic recognition means is terminated and the management station is turned off, by referring to this database,
The network configuration diagram as shown in FIG. 25 can be displayed again.

As described above, according to the present embodiment, the reachability means and the network management protocol are used as the network construction means, and the node existing in the network connected by the relay device having the relay judgment function and the network thereof. The configuration of can be automatically and efficiently recognized, and the burden on the network administrator can be greatly reduced.

[0081]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) The network device connected to the network can be efficiently detected without omission.

(2) It is possible to recognize how the network devices are connected.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an embodiment of a network device of the present invention.

FIG. 2 is a configuration diagram of a network management device of the present invention.

FIG. 3 is a network configuration management table created by the automatic recognition means shown in FIG.

FIG. 4 is a flow chart of processing for detecting a network device provided in the management device shown in FIG.

5 is a flow chart of a process of acquiring detailed information of a network device detected by the management device shown in FIG.

FIG. 6 is a flow chart of a process in which the management device shown in FIG. 2 detects a network device connected to a segment indirectly connected via the network device.

FIG. 7 is a flowchart of the entire automatic recognition means shown in FIG.

FIG. 8 is an example of a network including a plurality of network devices.

9 is a network configuration diagram recognized by a management device after performing the processing shown in FIGS. 3 and 4 on the network of FIG.

FIG. 10 shows the network device shown in FIG.
5 is a network configuration diagram recognized by a management device after performing the processing shown in FIG.

FIG. 11 is a diagram showing the network device shown in FIG.
6 is another network configuration diagram recognized by the management device after performing the processing shown in FIG.

FIG. 12 is a diagram showing a network configuration diagram recognized by a management apparatus after performing automatic recognition processing.

FIG. 13 is a diagram showing an example of networks connected by a relay device to which the network configuration recognition method of the present invention is applied.

FIG. 14 is a hardware block diagram of a network management station including automatic recognition means according to the present invention.

15 is a software configuration of the management station shown in FIG.

16 is a flow chart of a process in which the network management station shown in FIG. 13 detects a node existing in the network.

FIG. 17 is a flowchart of a process of determining whether the node detected by the network management station shown in FIG. 13 is a bridge.

FIG. 18 is a flow chart of a process in which the network management station shown in FIG. 13 determines which interface side the management station is connected to among the plurality of interfaces that the bridge has.

FIG. 19 is a flowchart of a process of determining whether the node detected by the network management station shown in FIG. 13 is at the tip of the bridge as viewed from the management station.

FIG. 20 is a flowchart of a process of determining to which interface of the bridge the node, which is determined to be at the bridge end as viewed from the management station, is connected to.

FIG. 21 is a network configuration diagram recognized by the management station after performing the processing shown in FIG. 20.

22 is a network configuration diagram recognized by the management station after the process shown in FIG. 21 is performed on the bridge A. FIG.

FIG. 23 is a network configuration diagram recognized by the management station after performing the same processing as that shown in FIG. 21 on the bridge B as well.

FIG. 24 is a network configuration diagram recognized by the management station after performing the same processing as that shown in FIG. 23 on the bridge A;

FIG. 25 is a network configuration diagram recognized by a management station after performing the processing shown in FIG.

FIG. 26 is an example of a database created by the automatic recognition unit shown in FIG.

[Explanation of symbols]

 101 Network Device 102 CPU (Central Processing Unit) 103 Nonvolatile Memory 104 Bus 105 Frame Sending Unit (Trap Sending Unit) 106 Search Frame Sending Unit 107 SNMP Communication Unit 108 Main Storage Device 201 Management Device

Claims (6)

[Claims] 1. In a network device such as a concentrator and a relay device connected to a network such as a local area network, when a search frame is received, a frame transmitting means for periodically transmitting the frame to the management device after that is designated. A network device, comprising: a search frame transmitting means for transmitting a search frame from an interface. 2. A network device detection method for detecting a network device such as a concentrator and a relay device connected to a network such as a local area network, wherein a management device multicasts a search frame and receives the search frame. A method for detecting a network device, wherein the management device detects the network device by periodically transmitting the frame to the management device after the network device receives the search frame. 3. A network device detection method for detecting a network device such as a concentrator and a relay device connected to a network such as a local area network, wherein a management device multicasts from an interface in which a search frame is designated for the network device. The network device that is transmitted and receives the above-mentioned frame periodically transmits the frame to the management device after receiving the frame, so that the management device is connected to the segment to which the management device is connected via the network device. A method for detecting a network device, comprising: 4. A network configuration recognizing method for recognizing a network configuration such as a local area network, wherein the management device multicasts a search frame, and the network device receiving the search frame,
A method for recognizing a network configuration, which comprises recognizing a network configuration by periodically transmitting a frame to a management device after receiving a search frame for each segment. 5. A network configuration recognizing method for recognizing a network configuration such as a local area network, wherein the management device causes a network device to perform multicast transmission from an interface in which a search frame is designated for each segment, and the network is received. A method for recognizing a network configuration, wherein an apparatus recognizes the network configuration by periodically transmitting a frame to a management apparatus after receiving the frame. 6. The management station broadcasts a response request frame to detect a node existing in the network, and the relay device uses a function of storing which interface another node is connected to. The management station determines which interface of the relay device is connected to it, and the management station suspends the frame relay function of each interface of the relay device, so that the detected other node connects to which interface of the relay device. A method for recognizing network configuration, characterized in that it is determined whether or not it has been.