JPH06232908A - Routing device - Google Patents

Abstract

PURPOSE:To reduce relay/transfer of a useless frame by detecting a loop so as to abort the frame when an identifier of a relay destination is recorded in the frame. CONSTITUTION:Suppose that a prescribed frame sent from a non-relay node (a) of a departure node to a non-relay node (d) is received by a relay node B. When the node B discriminates the frame not to be a relayed frame, the node B receives the frame and applies required processing. Furthermore, when the node B discriminates the frame to be a frame to be relayed, the node B transfers the frame and obtains a network number net #Ox04 of the non-relay node (d). Whether or not the number is registered in a history information area is discriminated. When it is discriminated that a loop is not generated at a current point of time, the required relay is processed and succeeding processing is executed. Furthermore, when it is discriminated that the frame is registered and the loop is generated, a frame abort section aborts the said frame, a loop detection display section detects and displays the occurrence of the loop and terminates the required job after display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a routing device, and more particularly to a routing device that is advantageously applied in a computer network system.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 62-53546 [Loop prevention control system in routing] discloses the following technical matters. That is, for a frame that flows in a given network with several relay nodes,
A node passing display area having a passing display area corresponding to each relay node is provided, and when a certain frame passes through the node (as the own node), the own node passing display is provided. There is. Then, when the frame that has passed through the own node in the past flows again, it is determined that a loop has occurred by checking the contents of the node passage display area, and the frame that has flowed again is discarded in response to this. It is supposed to do. By doing this, it is possible to immediately discard useless frames that cause loops,
It is designed to help reduce the load on the network.

By the way, when a loop occurs in a frame transmitted between a plurality of nodes in a certain predetermined network, the cause of the loop is [1] when a temporary error occurs in the routing information. And [2] there is a permanent error in the routing information. here,
[1] When the cause is that a temporary error has occurred in the routing information, it can be dealt with according to the method disclosed in the above publication. That is, when it is detected that a loop has occurred in a frame transmitted between a plurality of nodes in a given network, the frame is simply discarded, and processing such as retransmission in an upper layer in the network is performed. The required communication work can be continued normally. However, [2] If the cause is a permanent error in the routing information, normal communication work via the corresponding route cannot be continued.
Further, when the method of determining the occurrence of a loop disclosed in the above publication is used, the frame to be determined is discarded after being actually transferred in a loop.
In such a case, the transfer of the frame between the origin node of the loop occurrence and the node immediately before it becomes a waste of work.

[0004]

As described above, when a loop occurs in a frame transmitted between a plurality of nodes in a certain predetermined network, the cause of the loop is [1] its routing. It can be roughly classified into a case where a temporary error occurs in the information and a case where [2] a permanent error occurs in the routing information. Here, [1] When the cause is caused by a temporary error in the routing information, it is possible to deal with the above-described conventional technique for this type of routing. That is, when it is detected that a loop has occurred in a frame transmitted between a plurality of nodes in a given network, the frame is simply discarded, and processing such as retransmission in an upper layer in the network is performed. The required communication work can be continued normally. However,
[2] If the cause is that a permanent error has occurred in the routing information, normal communication work via the corresponding route cannot be continued. Further, when the method of determining the occurrence of a loop according to the above-described conventional technique is used, the frame to be determined is actually transferred in a loop and then discarded, and the starting node of the loop occurrence and its There is a problem that the transfer of the frame with the immediately preceding node becomes a wasteful work.

The present invention has been made in order to solve the above-mentioned problems, and in a network system adapted to perform loop detection by a record route method at the time of routing, a frame between a plurality of nodes in the network When a loop is detected in the transfer route, in addition to discarding the corresponding frame, by displaying or recording the information on the loop route on the console means or logger means in the node,
Notifying or transmitting to the administrator of the node that a loop has occurred in the route, and relaying useless frames when a loop occurs (by interrupting the transfer of the relevant frame when the occurrence of the loop is detected) It is intended to provide a routing device adapted to reduce forwarding. The present invention also achieves the following other objects. That is, in a network system configured to detect a loop by the record route method at the time of routing, when it is detected that a loop occurs in the route of a frame to be transferred, the frame is discarded and a predetermined By transmitting the loop occurrence notification frame, the adjacent relay node is notified of the occurrence of the loop; and at the corresponding relay node, the loop occurrence notification frame is received. By accurately reconstructing the route information related to the route to which the frame is to be transferred (that is, changing the frame transfer route to an appropriate one), the management related to the route information of the network system and its retention can be performed accurately. The purpose is to provide things.

[0006]

The present invention has been made to achieve the above object, and a routing device according to the present invention relays from a destination of a frame (20) to be relayed with reference to route information. In the routing device that determines the destination, records the identifier of the device itself (for example, the number of the network to which the device belongs) in the history information area (22) of the frame, and transmits it to the relay destination, the history of the frame to be relayed. Loop detecting means (16) for detecting a loop when the determined identifier of the relay destination is recorded in the information area and not detecting a loop when the identifier is not recorded,
A frame discarding means (17) for discarding the frame when a loop is detected by the loop detecting means. Further, another routing device according to the present invention includes a loop occurrence notification frame transmitting unit (14) for transmitting a loop occurrence notification frame to another routing device when the loop detection unit detects a loop, and another routing device. It further comprises a route information reconstructing means (12A) for reconstructing the route information when a loop occurrence notification frame is received from the device. Further, another routing device according to the present invention, when the loop detection means detects a loop, outputs the information regarding the route in which the loop has occurred by referring to the history information area of the frame concerned. It further comprises (16A). Further, another routing device according to the present invention, instead of the loop detection means (16), determines that the own device identifier is recorded in the history information area of the frame to be relayed, and records it as a loop detection. It is characterized in that it is adapted to fulfill the function of not detecting the loop when it is not.

[0007]

In the routing device according to the present invention configured as described above, when a loop is detected in the frame transfer route between a plurality of nodes in a predetermined network, the corresponding frame is discarded. In addition, by displaying or recording the information about the looped route on the console means or the logger means in the node, the administrator in the node is notified or transmitted that the loop has occurred in the route, and the loop is generated. There is an advantage that it is possible to reduce unnecessary relaying / transferring of frames when they occur. In addition, in the routing device according to the present invention, when it is detected that a loop has occurred in the route of a frame to be transferred, the frame is discarded and a predetermined loop occurrence notification frame is transmitted, thereby adjoining the adjacent frame. There is also an advantage that the relay node can be notified of that fact and the frame transfer path can be changed to an appropriate one.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a block diagram of a node device in a routing device according to a first embodiment of the present invention.
In FIG. 1, a node device 10 provided in a certain predetermined network includes a data processing unit 11 that performs required data processing on a transmitted / received frame, and a frame transmission / reception unit 12 for a frame transmitted / received in the network. ing. The frame transmission / reception unit 12 is composed of the following means. That is, the relay processing unit 18 that receives and relays a frame from the outside, the receiving unit 13 that passes the frame from the relay processing unit 18 to the data processing unit 11, and the history information that checks the history information regarding the frame from the outside. Inspection department 1
5, a frame discarding unit 17 that discards the corresponding frame based on the inspection result by the history information inspection unit 15, and a loop detection display unit regarding a loop whose occurrence is found based on the inspection result by the history information inspection unit 15. 1
6, a transmission unit 14 for transmitting the frame from the data processing unit 11 to the outside, and a history information setting unit 19 for setting the history information obtained by the history information inspection unit 15 at a proper place of the frame from the transmission unit 14. It consists of
And these means have the following interconnection relations. That is, the relay processing unit 18 that accepts a frame 20 described later is connected to the history information inspection unit 15 (which is connected to the history information setting unit 19 described later) and the reception unit 13, and the reception unit 13 is connected to the reception unit 13. Through the data processing unit 1
The frame 20 is passed to the frame 1. The loop detection display section 16 and the frame discard section 17 are connected to the history information inspection section 15. In addition, the data processing unit 1
The frame 20 from 1 is passed from the transmission unit 14 to the outside via the history information setting unit 19. Next, in the lower part of FIG. 1, a format of a certain predetermined frame 20 is illustrated, and here, the frame header 21 is an area including information indicating a receiving destination and a transmitting source of the corresponding frame. The history information area 22 is an area in which information about the previous history of the frame is held, such as a node through which the corresponding frame has passed in the past. The data area 23 is an area where the original data in the corresponding frame should be stored. Here, if the history information area 22 is additionally described, the network number of the relay network to which a predetermined frame is relayed is used as the identification code of the relay node related to the network. Then, in response to the relay operation of the frame, the identification code of the related relay node is held in a finite number of slots (5 slots in FIG. 1) in the order of the relay. Also, regarding the above network number,
As shown in FIG. 2 described later, for example, the network number related to the relay node A is 0x01. The same applies to the other relay nodes B, C, and D, which are 0x02, 0x03, and 0x04, respectively.

FIG. 2 is a system configuration diagram for explaining a network system to which the nodes according to the first embodiment are connected. In FIG. 2, A, B,
Each of C and D is a relay node, which occupies a required part in the network and relays / transfers a desired frame. Also, both a and d are non-relay nodes, the former being associated with relay node A,
On the other hand, the latter is associated with the relay node D. In FIG. 2, the network having the relay node A (net # 0x01) is the source of the frame and the network having the relay node D (net # 0x04).
It is assumed that a loop ABC is generated when the relay transfer of the frame is executed with the frame as the receiving source of the frame. At this time, the transition of information in the history information area 22 (FIG. 1) in the corresponding frame is illustrated in FIG. 3 below.

FIG. 3 is an explanatory diagram related to the mode of operation of the first embodiment (with respect to a state in which a certain predetermined loop has occurred). In FIG. 3, [1]: When a predetermined frame 20 (FIG. 1) is transmitted from the non-relay node a on the network # netx0x01 to the non-relay node d on the network # net0x04 In the first, the former non-relay node a firstly determines the network to which it belongs (that is, net # 0x0).
1) The predetermined frame 20 for the upper relay node A
To send. At this time, five slots in the history information area 22 in the frame 20 (# 0, #
0x00 indicating unused is written in all of the slots (1, 2, 2, 3 and 4 are assigned slot numbers) (However, in FIG. 3, only the lower two digits 00 are written for simplicity. ing). [2]: Next, at the relay node A, net # 0x04
When the predetermined frame 20 addressed to the relay node A is received and relayed, in the history information setting unit 19 (FIG. 1) belonging to the relay node A, the first slot (#
0), the number 0x01 corresponding to the own network is written, and then the relay node B belonging to net # 0x02
Is sent to. [3]: When the frame 20 is received by the relay node B, the relay processing unit 18 belonging to the relay node B should relay the destination information or the like in the frame header 21 of the frame 20 (that is, , It is not addressed to the current relay node B as its own node), and its transfer destination is obtained. here,
If there is no abnormality in the network system currently in operation,
The packet is transferred to the relay node D belonging to net # 0x04. For example, there is some abnormality in the route information regarding the transfer route.
Suppose that it is about to be transferred to the relay node C belonging to 03. In such a case, in the history information inspection unit 15 belonging to the node B, the history information area 22 of the frame 20 has a number 0x related to the network corresponding to the node C.
A check is made as to whether or not 03 is recorded. At this point, 0x03 is not recorded in the history information area 22, and the history information setting unit 1 belonging to the relay node B is
Second slot (# 1) of the history information area 22 in FIG.
After the number 0x02 corresponding to the own network is written in, the frame 20 is transmitted to the relay node C belonging to net # 0x03. [4]: When the frame 20 is received by the relay node C, the relay processing unit 1 belonging to this relay node C
8 also, the frame header 21 of the frame 20
Should be relayed from the destination information etc. in (
It is determined that it is not addressed to the current relay node C as its own node), and its transfer destination is obtained.
As mentioned above, there is something wrong with the network system running here, which is why net # 0x
It is assumed that the data is transferred to the relay node A belonging to 01. Also at this time, the history information inspection unit 15 belonging to the node C has the history information area 22 of the frame 20.
It is checked whether or not the number 0x01 relating to the network corresponding to the node A is recorded in. At this point, 0x01 has already been recorded in the history information area 22. Therefore, it is determined that a loop has occurred. In response to this, in the relay node C, the frame discarding unit 17 discards the corresponding frame 20, and the loop detection display unit 16 notifies the relevant department of the detection of the loop occurrence. Here, the operation of the loop detection display unit 16 will be described in detail. In addition to the information on the occurrence of the loop as described above, various information stored in the frame header 21 of the frame 20 and the time and the like are also included. The additional information is displayed on an appropriate console unit (not shown) provided for each node, or recorded on a logger unit (also not shown) having a required recording function. And
For example, information necessary for the judgment by the administrator designated for each node is added.

FIG. 4 is a flow chart for explaining an operation mode (loop detection mode) of the first embodiment. In FIG. 4, it is assumed that a predetermined node has received a frame from the preceding stage (S41). For example, from a non-relay node a, which is a departure node on the network called net # 0x01, to net # 0x04
Non-relay node d that is the reaching node on the network
Certain predetermined frame 20 heading toward the net # 0x02
Is received by the relay node B belonging to In the relay node B, it is judged whether or not the received predetermined frame 20 is to be relayed (S42). If the result of this determination is NO,
That is, when the relay node B, which is the current self-node, should receive it instead of relaying it, the relay node B receives it and performs the required processing (S43). On the other hand, the step S
When the result of the determination at 42 is YES, that is, when it is determined that the frame should be relayed, the number of the transfer destination network to which the received predetermined frame 20 is to be transferred is obtained (S44). According to the example here, ne to which the non-relay node d that is the transfer destination belongs
The network number t # 0x04 is required. In the subsequent step S45, it is determined whether or not the previously obtained transfer destination network number is already registered in the history information area 22 of the frame 20. When the result of this determination is NO, that is, when it is determined that the registration has not been made yet and the loop has not occurred at the present time point, a certain required relay process is performed (S48). The subsequent processing is appropriately performed. On the other hand, when the result of the determination in step S45 is YES, that is, when it is determined that registration has already been performed and a loop has occurred, the frame discarding unit 17 causes the corresponding frame 2
0 is discarded, and the detection of loop occurrence is displayed on the loop detection display unit 16 (S46), and the required work is completed (S47).

FIG. 5 is a block diagram showing the configuration of a node device in the routing device according to the second embodiment of the present invention. In FIG. 5, a node device 10 provided in a predetermined network transfers a data processing unit 11 that performs required data processing on a transmitted / received frame, a frame transmission / reception unit 12 regarding a frame transmitted / received in the network, and a transfer in the network. It is configured by a route information management / update unit 12A that manages the route information of a frame to be updated and performs a required update, and a loop route information output unit 16A that outputs information about a loop generated when the frame is transferred. The frame transmission / reception unit 12 is composed of the following means. That is, the relay processing unit 18, which receives and relays a frame from the outside,
Based on the receiving unit 13 that passes the frame from the relay processing unit 18 to the data processing unit 11, the history information inspection unit 15 that checks the history information regarding the frame from the outside, and the inspection result in the history information inspection unit 15, A frame discarding unit 17 that discards the corresponding frame, a loop detection display unit 16 regarding a loop whose occurrence is found based on the inspection result by the history information inspection unit 15, and a data processing unit 1.
The transmission unit 14 sends out the frame from the outside to the outside, and the history information setting unit 19 which sets the history information obtained by the history information inspection unit 15 in the proper place of the frame from the transmission unit 14. . And these means have the following interconnection relations. That is, the history information inspection unit 15 that temporarily accepts the frame 20 has the loop detection display unit 16 (this is the loop route information output unit 1
6A), the frame discarding unit 17 and the relay processing unit 18 (which are connected to the history information setting unit 19 and the route information managing / updating unit 12A), and the receiving unit 13 The frame 20 is also connected to the data processing unit 11.
Further, the frame 20 from the data processing unit 11 is passed to the outside from the transmission unit 14 via the history information setting unit 19 together with required information from the route information management / updating unit 12A.

The system configuration of the network to which the nodes according to the second embodiment are connected is shown in FIG. 2 as a system configuration diagram for explaining the above-mentioned first embodiment.
Is similar to. The second embodiment will be described below with reference to FIG. 2 again. As described above, each of A, B, C, and D is a relay node, which occupies a required part in the network and relays / transfers a desired frame. Further, both a and d are non-relay nodes, the former is associated with the relay node A, while the latter is associated with the relay node D. In FIG. 2, the network (net # 0x01) having the relay node A is now the source of the frame, and the network (net # 0x01) having the relay node D (net
It is assumed that a loop A-B-C occurs when the relay transfer of the frame is executed with # 0x04) as the receiving source of the frame. At this time, the transition of information in the history information area 22 (FIG. 5) in the corresponding frame is illustrated in FIG. 3 used in the description of the first embodiment.

FIG. 3 is an explanatory diagram which can be used for the mode of operation of the second embodiment (mode when a certain predetermined loop occurs). In FIG. 3, [1]: when a predetermined frame 20 (FIG. 5) is transmitted from the non-relay node a on the network # netx0x01 to the non-relay node d on the network # net0x04 In the first, the former non-relay node a firstly determines the network to which it belongs (that is, net # 0x0).
1) The predetermined frame 20 for the upper relay node A
To send. At this time, five slots in the history information area 22 in the frame 20 (# 0, #
0x00 indicating unused is written in all of them (slot numbers of 1, # 2, # 3, and # 4 are given). [2]: Next, at the relay node A, net # 0x04
When the predetermined frame 20 addressed to the relay node A is received and relayed, the history information setting unit 19 (FIG. 5) belonging to the relay node A has the first slot (#
0), the number 0x01 corresponding to the own network is written, and then the relay node B belonging to net # 0x02
Is sent to. [3]: When the frame 20 is received by the relay node B, the history information inspection unit 15 belonging to this relay node B inspects the contents of the history information area 22 of the frame 20. As a result of this check, since the net number related to the relay node B which is the current self node does not exist in the slot of the history information area 22, it is regarded as a normal relay and the relay processing corresponding to this is performed. Is applied. Here, if there is no abnormality in the currently operating network system, it is transferred to the relay node D belonging to net # 0x04. For example, there is some abnormality in the route information regarding the transfer route, For this,
It is assumed that an attempt is made to transfer to the relay node C belonging to net # 0x03. At this time, in the history information setting unit 19 belonging to the node B, the second slot (# 1) of the history information area 22 is assigned the number 0 corresponding to its own network.
After writing x02, the frame 20 is transmitted to the relay node C belonging to net # 0x03. [4]: When the frame 20 is received by the relay node C, the history information inspection unit 15 belonging to the relay node C also receives the history information area 2 of the frame 20.
The contents of 2 are examined. As a result of this check, since the net number related to the relay node C which is the current self node does not exist in the slot of the history information area 22, it is regarded as a normal relay and the relay processing corresponding to this is performed. Is applied. However, for example, there is some abnormality in the route information related to the transfer route, and for this reason,
It is assumed that the data is transferred to the relay node A belonging to # 0x01. At this time, in the history information setting unit 19 belonging to the node C, the number 0x03 corresponding to the own network is assigned to the third slot (# 2) of the history information area 22.
Is written, the transmission is performed to the relay node A belonging to net # 0x01. When the frame 20 returned in a loop in this way is accepted by the relay node A, the history information inspection unit 1 belonging to this relay node A
At 5, the contents of the history information area 22 of the frame 20 are inspected. As a result of this check, in the first slot (# 0) of the history information area 22, the number 0x of the network belonging to the relay node A which is the current self node is displayed.
The presence of 01 is detected, and it is determined that a loop has occurred. In response to the notification of the result of this determination, the frame discarding unit 17 discards the corresponding frame 20 and also notifies the route information management / updating unit 12A that a loop has occurred. From this route information management / update unit 12A, a loop detection notification frame including additional information such as required information in the frame header 21 in the frame 20 is transmitted to the adjacent relay node. Further, in the adjacent relay node that receives such a loop detection notification frame, the route information management / updating unit 12A belonging to the node performs accurate reconstruction of the route information regarding the route to which the frame is transferred. , The required route information is properly retained.

FIG. 6 is a diagram showing the construction of a node device in a routing device according to the third embodiment of the present invention. In FIG. 6, a node device 10 provided in a predetermined network includes a data processing unit 11 that performs required data processing on a frame to be transmitted and received, and
It is composed of a frame transmitting / receiving unit 12 relating to frames transmitted / received in the network. The frame transmission / reception unit 12 is composed of the following means. That is, the relay processing unit 18 that receives and relays a frame from the outside, the receiving unit 13 that passes the frame from the relay processing unit 18 to the data processing unit 11, and the history information that checks the history information regarding the frame from the outside. Inspection department 1
5, a frame discarding unit 17 that discards the corresponding frame based on the inspection result by the history information inspection unit 15, and a loop detection display unit regarding a loop whose occurrence is found based on the inspection result by the history information inspection unit 15. 1
6, a transmission unit 14 for transmitting the frame from the data processing unit 11 to the outside, and a history information setting unit 19 for setting the history information obtained by the history information inspection unit 15 at a proper place of the frame from the transmission unit 14. It consists of
And these means have the following interconnection relations. That is, the history information inspection unit 15 that once receives a frame 20 described later is connected to the loop detection display unit 16, the frame discarding unit 17, and the relay processing unit 18 (which is connected to the history information setting unit 19 described later). Further, the frame 20 is also connected to the receiving unit 13 so as to pass the frame 20 to the data processing unit 11. Further, the frame 20 from the data processing unit 11 is adapted to be passed from the transmission unit 14 to the outside via the history information setting unit 19.
Next, in the lower part of FIG. 6, the format of a certain predetermined frame 20 is illustrated, and here, the frame header 2
Reference numeral 1 is an area including information indicating a receiving destination and a transmission source of the corresponding frame, and the history information area 22 is, for example,
This is an area in which information about various previous histories of a frame is held, such as a node through which the corresponding frame has passed in the past. The data area 23 is an area where the original data in the corresponding frame should be stored.

The system configuration of the network to which the nodes according to the third embodiment are connected is shown in FIG. 2 as a system configuration diagram for explaining the above-mentioned first embodiment.
Is similar to. The third embodiment will be described below with reference to FIG. 2 again. As described above, A, B, C and D are relay nodes,
It occupies a required part in the network and relays and transfers a desired frame. Also, a and d
Are non-relay nodes, the former being associated with relay node A, while the latter being associated with relay node D. In FIG. 2, the network (net # 0x01) having the relay node A is now the source of the frame, and the network (ne
It is assumed that a loop ABC is generated when the relay transfer of the frame is executed with t # 0x04) as the receiving source of the frame. At this time, the transition of information in the history information area 22 (FIG. 6) in the corresponding frame is illustrated in FIG. 3 used in the description of the first embodiment.

FIG. 3 is an explanatory diagram which can be used for the operation mode of the third embodiment (mode when a certain predetermined loop occurs). In FIG. 3, [1]: when a predetermined frame 20 (FIG. 6) is transmitted from the non-relay node a on the network net # 0x01 to the non-relay node d on the network net # 0x04 In the first, the former non-relay node a firstly determines the network to which it belongs (that is, net # 0x0).
1) The predetermined frame 20 for the upper relay node A
To send. At this time, five slots in the history information area 22 in the frame 20 (# 0, #
0x00 indicating unused is written in all of the slots (1, 2, 2, 3 and 4 are assigned slot numbers) (However, in FIG. 3, only the lower two digits 00 are written for simplicity. ing). [2]: Next, at the relay node A, net # 0x04
When the predetermined frame 20 addressed to the relay node A is received and relayed, in the history information setting unit 19 (FIG. 6) belonging to the relay node A, the first slot (#
0), the number 0x01 corresponding to the own network is written, and then the relay node B belonging to net # 0x02
Is sent to. [3]: When the frame 20 is received by the relay node B, the history information inspection unit 15 belonging to this relay node B inspects the contents of the history information area 22 of the frame 20. As a result of this check, since the net number related to the relay node B which is the current self node does not exist in the slot of the history information area 22, it is regarded as a normal relay and the relay processing corresponding to this is performed. Is applied. Here, if there is no abnormality in the currently operating network system, it is transferred to the relay node D belonging to net # 0x04. For example, there is some abnormality in the route information regarding the transfer route, For this,
It is assumed that an attempt is made to transfer to the relay node C belonging to net # 0x03. At this time, in the history information setting unit 19 belonging to the node B, the second slot (# 1) of the history information area 22 is assigned the number 0 corresponding to its own network.
After writing x02, the frame 20 is transmitted to the relay node C belonging to net # 0x03. [4]: When the frame 20 is received by the relay node C, the history information inspection unit 15 belonging to the relay node C also receives the history information area 2 of the frame 20.
The contents of 2 are examined. As a result of this check, since the net number related to the relay node C which is the current self node does not exist in the slot of the history information area 22, it is regarded as a normal relay and the relay processing corresponding to this is performed. Is applied. However, for example, there is some abnormality in the route information related to the transfer route, and for this reason,
It is assumed that the data is transferred to the relay node A belonging to # 0x01. At this time, in the history information setting unit 19 belonging to the node C, the number 0x03 corresponding to the own network is assigned to the third slot (# 2) of the history information area 22.
Is written, the transmission is performed to the relay node A belonging to net # 0x01. When the frame 20 returned in a loop in this way is accepted by the relay node A, the history information inspection unit 1 belonging to this relay node A
At 5, the contents of the history information area 22 of the frame 20 are inspected. As a result of this check, the number 0 of the network to which the relay node A, which is the current self node, belongs
The existence of x01 is discovered, and it is determined that a loop has occurred. In response to this, the corresponding frame 20 is discarded by the frame discarding unit 17, and the loop detection display unit 16 is notified that this loop has occurred. From the loop detection display unit 16, various information in the frame header 21 in the frame 20, time and other additional information are displayed on an appropriate console unit provided for each node, or a required recording function is provided. For example, the information is recorded in the logger unit having the information, and information necessary for judgment by the administrator designated for each node is added.

[0018]

As described above, according to the routing device of the present invention, when a loop is detected in the frame transfer route between a plurality of nodes in a predetermined network, the corresponding frame is detected. In addition to discarding, by displaying or recording the information about the looped route on the console means or logger means in the node, the administrator in the node is notified or transmitted that the route has a loop. At the same time, it is possible to reduce unnecessary relaying / transferring of frames when a loop occurs (by eliminating unnecessary transfer of frames). In addition, in the routing device according to the present invention, when it is detected that a loop has occurred in the route of a frame to be transferred, the frame is discarded and a predetermined loop occurrence notification frame is transmitted, thereby adjoining the adjacent frame. There is also an effect that the relay node can be notified of that fact and the frame transfer route can be changed to an appropriate one.

[Brief description of drawings]

FIG. 1 is an exemplary configuration diagram of a node device in a routing device according to a first embodiment of the present invention.

FIG. 2 is a system configuration diagram for explaining a network system to which nodes according to the above embodiments are connected.

FIG. 3 is an explanatory diagram related to an operation mode of the above-described embodiment (related to a state in which a certain predetermined loop has occurred).

FIG. 4 is a flow chart for explaining a mode of operation of the above embodiment.

FIG. 5 is a diagram illustrating a configuration of a node device in the routing device according to the second embodiment of the present invention.

FIG. 6 is an exemplary configuration diagram of a node device in a routing device according to a third embodiment of the present invention.

[Explanation of symbols]

10 --- node device; 11 --- data processing unit; 12 ---
Frame transmitting / receiving unit; 13 --- Reception unit; 14 --- Transmission unit;
15 --- History information inspection unit; 16 --- Loop detection display unit;
17 --- Frame discarding unit; 18 --- Relay processing unit; 19-
-History information setting unit; 20 --- Frame; 21--Frame header; 22--History information area; 23--Data area.

Claims (4)

[Claims] 1. A routing device for determining a relay destination from a destination of a frame to be relayed by referring to route information, recording an identifier of the own device in a history information area of the frame, and transmitting the identifier to the relay destination. When the determined relay destination identifier is recorded in the history information area of the frame to be relayed, loop detection is performed, and when it is not recorded, loop detection is performed, and loop detection is performed by the loop detection means. A frame discarding unit that discards the frame when detected, and a routing device. 2. A loop occurrence notification frame transmitting means for transmitting a loop occurrence notification frame to another routing device when the loop detection means detects a loop, and a loop occurrence notification frame received from another routing device. The routing device according to claim 1, further comprising: route information reconstructing means for reconstructing the route information. 3. A loop route information output means for outputting information on a route in which a loop has occurred by referring to a history information area of the frame when the loop detection means detects a loop. Alternatively, the routing device according to claim 2. 4. A loop which, instead of the loop detecting means, detects a loop when the identifier of the own device is recorded in the history information area of the frame to be relayed, and a loop non-detection when the identifier is not recorded. The routing device according to claim 2 or 3, further comprising detection means.