JPH09247207A - Packet routing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the other normal transmission line even if a one-way fault occurs in one transmission line. SOLUTION: Opposite destinations are set to all packets which are sent from respective packet routing devices A-D. Consequently, routes can be set, packet by packet, and even if a fault occurs to a line 11, an origination source can recognize the fault. Then information regarding the line fault is broadcasted, and then the respective packet routing devices A-D can recognize the topology of the whole packet switching network and calculate the shortest route for each packet routing device according to specific routing algorithm. For the fault of the line, a diagnostic packet is defined and sent periodically, so that a reception-side device can detect the fault.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet routing system, and more particularly to a packet routing system for performing routing when packets are transferred between a plurality of devices.

[0002]

2. Description of the Related Art As a conventional packet routing system, there is one disclosed in Japanese Patent Laid-Open No. 3-230643. This is to set in advance which relay line to use as a bypass route when a failure occurs in the relay line. For example, when constructing a packet switching network, the data as shown in FIG. 19 is preset as a table.

In the figure, assuming that the route number "3" of a relay line is the current route number, the detour route number column indicates two detour routes when a fault occurs in the relay line. Each route number is written. That is, the route number "2, 1" is written on one side, and the route number "4, 1" is written on the other side. Then, when a failure occurs in the relay line, the detour table is referred to based on the route number “3” of the relay line and any one of the above route numbers “2, 1” and “4, 1” Either one is selected. The selected route becomes the detour route.

[0004]

In the above-mentioned conventional packet routing system, it is necessary to set data in a table when constructing a packet switching network in advance. For this reason, there is a drawback that the relay route must be reset in all the switching devices when adding the switching devices.

Further, if the delivery of the packet cannot be confirmed, the line is treated as a fault, so that it is not possible to confirm the delivery when there is a fault in only one direction of the transmission path, and bidirectional use is not possible. It was prohibited. For this reason, when a failure occurs in the relay line, there is a drawback that both directions cannot be used even though one direction is normal and the line cannot be effectively used.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and its purpose is to effectively utilize the other line which is normal even if one direction of the line is disturbed. It is to provide a packet routing system capable.

Another object of the present invention is to provide a packet routing system capable of automatically performing routing without the need for resetting a relay route even when adding a switching device.

[0008]

A packet routing system according to the present invention is a packet routing system for performing routing when packets are transferred between a plurality of devices, each of the devices from another device to its own device. Diagnostic means for diagnosing the state of the transmission line, and sending means for sending the diagnostic result to all devices in the network,
Holding means for holding the diagnosis result sent from another device in its own device, and routing is performed according to the held contents in the holding means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the present invention is as follows.

Since the route can be set for each packet by setting the destination for all the packets to be transmitted, it is necessary to reset the communication path if there is a detour even if a line failure occurs. Absent. Further, by recognizing the failure by the sender, it is possible to prevent the packet from being carelessly looped in the communication path.

If the delivery confirmation is not performed between the routing devices, it is possible to use the other transmission line which is normal when a one-way failure occurs in the transmission line.

By broadcasting the information on the line failure, each packet routing device can generate the information on the topology of the entire packet switching network.
By holding the information of all packet routing devices in each packet routing device, the topology of the entire packet switching network can be recognized, and the shortest route can be calculated in each packet routing device by a predetermined routing algorithm. .

The line failure can be detected by the receiving side device by defining a diagnostic packet and transmitting this packet periodically.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a packet routing system according to the present invention. In the figure, a packet routing system according to an embodiment of the present invention includes four packet routing devices A,
It is composed of B, C and D. As shown in the figure, the packet routing device A is directly connected to the other packet routing devices B, C and D.
The packet routing device D is directly connected to the other packet routing devices A, B and C.

On the other hand, the packet routing device B is directly connected to the other packet routing devices A and D, but is not directly connected to the packet routing device C. The packet routing device C is directly connected to the other packet routing devices A and D, but is not directly connected to the packet routing device B.

Now, assuming that a packet is transmitted from the packet routing device D to the packet routing device A, since there is no abnormality in all the transmission lines, the line 1
1 is used for the transmission. Also, assuming that the packet is transmitted from the packet routing device B to the packet routing device D, the line 14 is used for the transmission.

FIG. 2 is a diagram showing an example of the structure of packets transmitted and received between the packet routing devices in FIG.
In the figure, a packet 1 is composed of data 4 and a header 7 added to this data. The header 7 includes destination information 5 indicating a destination device and transmission source information 6 indicating a transmission source device.

In this example, the destination information 5 is "D" and the transmission source information 6 is "A". That is, the header 7 indicates that the destination device is the packet routing device D and the source device is the packet routing device A. As a result, when relaying this packet, the direct relay line 11 to the destination device D is selected.

FIG. 3 shows route information generated by each packet routing device in this system. In the figure, the packet routing devices A to A in FIG.
The route information generated by each of D is shown.

Referring to FIG. 1A, when transmitting from the packet routing device A to the packet routing device B, the packet routing device B is selected as the route device and the packet routing device B directly transmits without passing through another packet routing device. To be done. Further, when transmitting from the packet routing device A to the packet routing device C, the packet routing device C is selected as the route device, and the packet routing device C is directly transmitted without passing through another packet routing device. Furthermore, when transmitting from the packet routing device A to the packet routing device D, the packet routing device D is selected as the route device,
It is sent directly without going through another packet routing device.

Next, referring to FIG. 3B, when transmitting from the packet routing device B to the packet routing device A, the packet routing device A is selected as the route device and does not go through another packet routing device. Sent directly to. When transmitting from the packet routing device B to the packet routing device C, the packet routing device D is used as the root device.
Is selected and transmitted via this packet routing device D. Further, when transmitting from the packet routing device B to the packet routing device D, the packet routing device D is selected as the route device,
It is sent directly without going through another packet routing device.

Similarly, referring to FIG. 1C, the packet routing device C to the packet routing device A
When the packet is transmitted to the packet routing device A, the packet routing device A is selected as the route device, and the packet routing device A is directly transmitted without passing through another packet routing device. When transmitting from the packet routing device C to the packet routing device B, the packet routing device A is selected as the route device, and the packet routing device A transmits. Further, when transmitting from the packet routing device C to the packet routing device D, the packet routing device D is selected as the route device and is directly transmitted without passing through another packet routing device.

Then, referring to FIG. 3D, the packet routing device D to the packet routing device A
When the packet is transmitted to the packet routing device A, the packet routing device A is selected as the route device, and the packet routing device A is directly transmitted without passing through another packet routing device. When transmitting from the packet routing device D to the packet routing device B, the packet routing device B is selected as the route device, and the packet routing device B is directly transmitted without passing through another packet routing device. Further, when transmitting from the packet routing device D to the packet routing device C, the packet routing device C is selected as the route device and is directly transmitted without passing through another packet routing device.

As described above, each packet routing device selects the relay line by using the route information shown in FIG. If the relay line selected at this time matches the source relay line, the packet is discarded.

FIG. 4 is a diagram showing the stored contents of the memory provided in the all packet routing device. As shown in the figure, the memory stores information indicating the states of the relay lines of all the packet routing devices that form the packet network generated under the configuration of FIG.

Item 8, "Detection device" in the figure, indicates a packet routing device that monitors the state of the relay line. The "opposite device" of item 9 indicates the opposite packet routing device connected by the relay line. Furthermore, item 10 "line status" is
Indicates whether the trunk line is normal or abnormal.

By using the contents of this memory, each packet routing device can switch from item 9 to item 8
It is possible to judge whether the line to the device is normal or abnormal. Therefore, referring to the contents of this memory, each packet routing device should generate the route information shown in FIG. 3 from the route information from its own device to another device using a routing algorithm such as a branch and bound method. You can This generation procedure will be described later.

FIG. 5 shows, as an example, information indicating the state of the relay line managed by the packet routing device A. Referring to the figure, it can be seen that the detection device, that is, the packet routing device A, is in a normal state of all the trunk lines from the packet routing devices B, C, and D, which are other devices, to the own device.

Each packet routing device periodically sends out a diagnostic packet. Therefore, if the device that receives the diagnostic packet cannot receive it at the time when the diagnostic packet should be received, the line from the device that should send the packet to the device is abnormal. Can be determined. This diagnostic result is
It may be sent immediately when an abnormality is detected, or may be sent periodically regardless of the abnormality detection. In this case, the diagnostic result is sent by broadcast transmission,
It is sent to all packet routing devices.

Here, the sending operation of the diagnostic packet in each packet routing device will be described with reference to FIG. The figure is a flowchart showing a process of transmitting a diagnostic packet in each packet routing device. First, since the diagnostic packet is sent out periodically, it is determined whether or not the current time and the time to be sent match (step 601). When the times coincide with each other, that is, when the transmission time comes, a diagnostic packet having a predetermined content is sent to the partner device (step 602). This diagnostic packet has a predetermined content. Instead of step 601, a counter for measuring a fixed time may be provided and the counter may be sent at a fixed time.

Next, the fault detection processing operation in each packet routing device will be described with reference to FIG.
First, it is determined whether the current time and the time to be received match (step 701). If the times match, that is, the time that should be received,
It is determined whether a diagnostic packet has been received (step 702). When the diagnostic packet is not received, it is considered that an abnormality has occurred in the line with the partner device. Since this diagnostic packet has a predetermined content and can be discriminated from other packets, it can be determined whether or not the packet has been received.

If it has been received, the process returns to step 701.

On the other hand, if it has not been received, the content of the information of the relay line is rewritten (step 703). Then, the information on the relay line after the rewriting is broadcasted (step 7).
04).

As described above, when an abnormality occurs in the line, information indicating the state of the relay line from another device to the own device,
That is, the diagnostic result of the line by the diagnostic packet is sent from each of all the packet routing devices by broadcast transmission. Therefore, all the trunk lines, that is, the states in both directions of the transmission line are separately broadcast. Then, each packet routing device receives this broadcast transmission and stores it in the memory (FIG. 4) described above.

Next, the operation of each packet routing device that has received the information on the trunk line will be described with reference to FIG. First, each packet routing device determines whether or not it has received the information of the trunk line (step 80).
1). When it is received, the contents of the memory (FIG. 4) are updated according to the received information (step 80).
2).

Further, with reference to FIG. 9, the operation when a one-way failure occurs in the relay line will be described. In the figure,
In the system of FIG. 1, there is shown a case where a unidirectional failure occurs in the line 11 from the packet routing device D to the packet routing device A. In such a case, the packet routing device A cannot receive the above-mentioned diagnostic packet at the time when it should be received, and therefore determines that the line 11 has failed. As a result of this determination, a part of the trunk line information shown in FIG. 5 is changed as shown in FIG. Referring to FIG. 10, item 12,
That is, the line status from the packet routing apparatus D, which is the opposite apparatus, to the packet routing apparatus A, which is the own apparatus, is changed from "normal" to "abnormal". The changed information in FIG. 10 is broadcast from the packet routing device A to all the packet routing devices. Receiving this broadcast transmission, each packet routing device changes the contents stored in the memory provided in the device itself from the contents shown in FIG. 4 to the contents shown in FIG.

Referring to FIG. 11, which shows the contents stored in the memory after the change, item 13, that is, the line status from the packet routing device D which is the opposite device to the packet routing device A which is the detection device is "normal".
Has been changed from "abnormal". In accordance with the contents stored in the new memory shown in FIG. 11, the packet routing device D generates route information as shown in FIGS. 12 (a) to 12 (d). That is, in order not to use the line 11 which has become a one-way obstacle, in FIG.
The item 15 of the above is changed from “A” (see FIG. 3D) to “B”. Therefore, when transmitting data from the packet routing device D to the packet routing device A, the packet routing device B is selected as the route device.

In FIG. 12, other items are the same. Therefore, for example, when transmitting data from the packet routing device A to the packet routing device D, the packet routing device D is selected as the route device, and the packet routing device A directly transmits to the packet routing device D. .

Further, as shown in FIG. 13, a case where a failure occurs in the line 14 from the packet routing device B to the packet routing device D will be described. In this case, a part of the trunk line information in the packet routing device D is changed as shown in FIG. That is, item 17, that is, the line state from the packet routing device B which is the opposite device to the packet routing device D which is the own device is changed to “abnormal”. The information in FIG. 14 after this change is broadcasted from the packet routing device D to all the packet routing devices, and each packet routing device that receives the information changes the stored contents of the memory provided in its own device as shown in FIG. The contents shown in FIG. 15 are changed to the contents shown in FIG.

Referring to FIG. 15 showing the contents stored in the memory after the change, in addition to item 13 described above, item 1
8, that is, a packet routing device D that is a detection device
The line state from the packet routing device B, which is the opposite device to the above, is changed from "normal" to "abnormal".

In the packet routing device B according to the contents stored in the new memory shown in FIG.
6 (a) to 6 (d), route information is generated. That is, in order not to use the line 14 that has become a one-way obstacle, the item 16 in FIG.
(See FIG. 12B) is changed to "A". Therefore, when transmitting data from the packet routing device B to the packet routing device D, the packet routing device A is selected as the route device.

Here, an example of the routing using FIG. 4 will be described with reference to FIGS. 17 and 18. In this example, the routing by the well-known branch and bound method will be described.

The procedure for generating a route in the packet routing device A based on the contents stored in the memory shown in FIG. 4 is as follows. That is, first, the device B is selected as the target device (step 1 in FIG. 17-
1). Here, since all the devices have not been selected (step 1-2), the target device B is set in the route information and the route information is emptied (step 1-3). As a result, the route information becomes {B}.

As a result, the route generation process is performed using the device B as the parameter (step 1-4). 18, the detection device A whose parameter P1 = B is the opposite device and the line state is normal is selected (step 2-1). Since all the detection devices have not been selected (step 2-2) and the detection device A is its own device (step 2-3), the route information is added to the route information (step 2-8). As a result, the route information becomes {B}.

Returning to step 2-1, the parameter P1 =
B is the opposite device and selects the detection device D whose line condition is normal. Not all detectors selected (step 2-
2) The detection device D is not the device A itself (step 2-
3) Also, since the detecting device D does not exist in the route information {B} (step 2-4), the detecting device A is routed to the route information {B}.
(Step 2-5). As a result, the route information becomes {B, D}.

Further, a route generation process is performed using the device D as a parameter (step 2-6). In step 2-1, the detection device A whose parameter P1 = D is the opposite device and the line state is normal is selected. Since not all the detection devices have been selected (step 2-2) and the detection device A is the device A itself (step 2-3), the route information {B, D} is changed to the route information {{B}}. Add (step 2-8). As a result, the route information becomes {{B}, {B, D}}.

Returning to step 2-1, the parameter P1 =
D is the opposite device and selects the detection device B whose line condition is normal. Not all detectors selected (step 2-
2) The detection device D is not the device A itself (step 2-
3) Also, since the detection device D exists in the route information {B, D} (step 2-4), the process returns to step 2-1.

In step 2-1, the parameter P1
= D selects the detection device C whose opposite device is the normal line state. Not all detectors selected (step 2
-2), the detection device C is not the device A itself (step 2-
3) Further, since the detecting device C does not exist in the route information {B, D} (step 2-4), the detecting device C is added to the route information {B, D} (step 2-8). As a result,
The route information is {B, C, D}.

Then, the parameter is set as the detector C,
Route generation processing is performed (step 2-6).

In step 2-1, the parameter P1
= C is the opposite device and the detection device A whose line condition is normal is selected. Not all detectors selected (step 2
-2), since the detection apparatus A is the self apparatus A (step 2)
-3), the route information {B, C, D} is added to the route information {{B}, {B, D}} (step 2-
8).

As a result, the route information is {{B}, {B,
D}, {B, D, C}}.

In step 2-1 the parameter P1
= C is the opposite device and the detection device D whose line condition is normal is selected. Not all detectors selected (step 2
-2), the detection device D is not the device A itself (step 2-
3) Since the detection device D is present in the route information {B, D, C} (step 2-4), the process returns to step 2-1.

In step 2-1, the parameter P1
= C is the opposite device and selects the detection device whose line status is normal. As a result, since all the detection devices have been selected (step 2-2), the process returns (step 2-9),
The detection device C is deleted from the route information {B, D, C} (step 2-7). As a result, the route information becomes {B, D}.

Returning to step 2-1, the parameter P1 =
D is the opposite device and selects the detection device B whose line condition is normal. Thereafter, the return of step 2-9 is repeated in the same manner, and finally the process returns to step 1-4 of FIG.

Moving to FIG. 17, the generated route information {{B}, {B, D}, {B, D, C}} is sorted by the number of relay stages (step 1-5). Then, the sorted route information {{B}, {B, D}, {B, D,
A route table is created from the sorting result of C}} (step 1-6). After that, the same processing is performed, and when all the devices are selected (step 1-2), the processing ends (step 1-7). By repeating the above processing, the route table corresponding to the route device B for the target device B, the route device C for the target device C, and the route device D for the target device D is obtained.

If the above process is performed based on each information shown in FIG. 11, it is possible for the source device to automatically set the shortest route to the target device to which the packet should be transmitted. Alternatively, the route may be obtained using the Dantzig method, the Nicholson method, or the like.

As described above, since each packet routing device can recognize the condition of the entire packet switching network, it is possible to recognize a one-way fault and not use only the faulty line. be able to. Therefore, even if a line failure occurs in one direction, it is possible to send and receive packets using the other normal line.

Further, since each packet routing device broadcasts the relay circuit information of its own device to all the packet routing devices and each packet routing device can recognize the information of all the routes, the new packet routing device is newly added. Even if additional routes are added, these can be recognized, and thus the packet routing device and additional routes can be easily added.

Further, each device in the packet switching network recognizes the state of the trunk line of the entire packet switching network,
The source device can automatically set the shortest route to the target device to which the packet should be transmitted. By not confirming the delivery, even if one direction of the transmission path becomes an obstacle, packets can be exchanged using the other transmission path that can be transmitted. A well-known asynchronous transfer mode (Asynchronous Transfer) is used as a protocol for not confirming delivery.
Mode) etc.

The present invention can take the following aspects in connection with the description of the claims.

(4) The packet routing system according to claim 3, wherein the sending means sends the diagnosis result by broadcast transmission.

(5) The packet routing system according to any one of claims 1 to 4, wherein the routing is performed by a branch and bound method.

[0064]

As described above, according to the present invention, each device in the packet switching network recognizes the state of the trunk line of the entire packet switching network, so that the packet switching device of the transmission source should transmit the packet. The shortest route to the switching device can be automatically set, and even if a line failure occurs in one direction, packets can be sent and received using the other line that is normal. In addition, since each device can recognize the information of all routes by broadcasting the trunk line information of its own device to all devices, even if a new node or route is added Therefore, there is an effect that a node and a route can be easily added.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a packet routing system according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a packet transmitted / received between each packet routing device in FIG.

FIG. 3 is a diagram showing route information generated by each packet routing device in the present system.

FIG. 4 is a diagram showing stored contents of a memory provided in an all packet routing device.

5 is a diagram showing an example of information indicating a state of a relay line managed by the packet routing device A. FIG.

FIG. 6 is a flowchart showing a diagnostic packet sending operation in each packet routing device.

FIG. 7 is a flowchart showing a failure detection processing operation in each packet routing device.

FIG. 8 is a flowchart showing the operation of each packet routing device that has received the information on the relay line.

9 is a diagram showing a case where a unidirectional failure occurs in the line from the packet routing device D to the packet routing device A in the system of FIG.

10 is a diagram showing the contents after the change of the information indicating the state of the relay line managed by the packet routing device A. FIG.

FIG. 11 is a diagram showing stored contents after a change of a memory provided in an all packet routing device.

FIG. 12 is a diagram showing the contents after change of route information generated by each packet routing device in this system.

13 is a diagram showing a case where a unidirectional failure has occurred in the line from the packet routing device B to the packet routing device D in the system of FIG.

FIG. 14 is a diagram showing the contents after the change of the information indicating the state of the relay line managed by the packet routing device D.

FIG. 15 is a diagram showing stored contents after a change of a memory provided in all packet routing devices.

FIG. 16 is a diagram showing the contents after the change of the route information generated by each packet routing device in this system.

FIG. 17 is a diagram showing a procedure of routing according to a branch and bound method.

FIG. 18 is a diagram showing a procedure of routing according to the branch and bound method and is a continuation of FIG. 17;

FIG. 19 is a diagram showing an example of detour information in a conventional packet routing system.

[Explanation of symbols]

 1 packet 4 data 5 destination information 6 source information 7 headers A to D packet routing device

Claims (3)

[Claims] 1. A packet routing system for performing routing when packets are transferred between a plurality of devices, each device comprising a diagnostic means for diagnosing a state of a transmission path from another device to the device itself. It includes a sending means for sending the diagnostic result to all the devices in the network, and a holding means for holding the diagnostic result sent from another device in its own device, and performs routing according to the contents held in the holding means. A packet routing system characterized by the above. 2. The diagnostic means determines that the transmission path from the other device to its own device is abnormal when the diagnostic packet periodically sent from the other device is abnormal. The packet routing system according to claim 1. 3. The packet routing system according to claim 1, wherein the sending means sends the diagnosis result of the diagnosing means at regular time intervals.