JP4413714B2 - Monitoring node device and monitoring method of communication system - Google Patents

Description

  The present invention relates to a monitoring node apparatus and a communication system monitoring method, and more particularly to a monitoring node apparatus and a communication system monitoring method for monitoring and switching redundant communication paths between networks.

  Currently, such as IP-VPN (Internet Protocol-Virtual Private Network) and L2-VPN (Layer 2 Protocol-Virtual Private Network), which are virtual private communication networks built via a wide-area IP communication network owned by a communication carrier An inter-base communication service using a simple relay network has been realized, and a communication network capable of realizing high-speed and large-capacity communication is being operated.

  In a communication network, when high reliability is required, a method of redundancy is prepared by preparing a plurality of relay networks. At this time, by using a routing protocol such as eBGP (external Border Gateway Protocol) between the routers on the user side, the routers themselves exchange health check signals with the opposite routers, and communication paths (hereinafter referred to as routes). ) Is detected, and a method for switching to a redundant route is known.

  Here, Ping (Packet Internet Grouper) is known as a command used for the health check. This Ping is a command for confirming whether the other party can communicate. For example, in Patent Document 1, a periodic ping test is performed on the LAN interface of the active router, and when there is no ping response, it is determined as defective and the standby router is switched to the active router.

In Patent Document 2, a ping command is executed to periodically monitor a failure of the working line route, and when a failure is detected, the route is switched to the protection line route.
JP-A-8-256173 Japanese Patent Laid-Open No. 2003-234749

  However, the method using the routing protocol as described above may not be used due to restrictions on the relay network side. In addition, in order to realize quick failure detection, if it is necessary to shorten the health check interval by the routing protocol performed by the router, or to perform health check with multiple networks, the throughput decreases due to the processing load of the router There was a problem. For this reason, it has been difficult to apply such a relay network to traffic that requires rapid failure detection and switching such as an IP telephone service. Such a problem cannot be solved by the techniques described in Patent Document 1 and Patent Document 2.

  The present invention has been made to solve the above-described problems of the prior art, and its purpose is to use a relay network that cannot perform fault monitoring and route switching using a routing protocol between routers on the user side. Another object of the present invention is to provide a monitoring node device and a communication system monitoring method capable of realizing high-speed route switching.

The monitoring node device according to claim 1 of the present invention relays between the first network and the second network by relaying between the routers provided in the first network and the second network through the working and backup paths. A monitoring node device used in a communication system configured by connecting to a second network, the content of rewriting at least the state of the network and the routing table held by the router of the network to which the device belongs A route monitoring table for holding information necessary for monitoring a failure of the network, sending means for sending a Ping to a router in the opposite network, and detecting a response to the Ping sent by the sending means detection means for, the detection means looking contains a switching unit performs a process of switching the path of the preliminary to the working if it can not detect the response, said switching means, said Refer to the information necessary for monitoring the network failure held by the network monitoring table, and delete it to rewrite the contents of the routing table held by the router of the network to which the device belongs. A process of generating a request and outputting the deletion request performs a process of switching the spare path to the current one . If a monitoring node device configured in this way is added to the network, rapid failure detection of the relay network can be realized. A configuration in which a monitoring unit is provided in each node device in the network to detect a failure autonomously is also possible. However, in this case, there is a problem that the design of the node needs to be changed, whereas such a problem does not occur if the monitoring node device is added to the network as described above. In addition, since a monitoring node device that outputs such a request to the router may be added to the network, a general configuration can be adopted for the router itself.

  The monitoring node device according to claim 2 of the present invention is the monitoring node device according to claim 1, wherein the switching unit switches the backup path to the active only when the number of times the response cannot be detected by the detection unit reaches a predetermined value. It is characterized by performing. Since the path is switched only when the number of times that a response cannot be detected reaches a predetermined value, it is possible to discriminate between a mere delay in response to Ping and a failure, and the path can be switched only in the latter case.

According to a third aspect of the present invention, there is provided a monitoring method for a communication system, in which the first network and the second network are relayed between the routers provided in the first network and the second network through the working and backup routes, respectively. And a communication system configured by connecting the second network and at least the state of the network and the content of rewriting the routing table held by the router of the network to which the device belongs A holding step for holding information necessary for monitoring a failure of the network, a sending step for sending a Ping to a router in the opposite network, and a response to the Ping sent in the sending step seen including a detection step, and a switching step performs a process of switching the path of the preliminary to the working if it can not detect the response in the detection step, the The replacement step rewrites the contents of the routing table held by the router of the network to which the own device belongs by referring to the information necessary for monitoring the network failure held by the holding step. Generating a deletion request for output, and outputting the deletion request, thereby performing a process of switching the spare path to the current one . By doing so, it is possible to quickly detect a failure in the relay network.

  In short, in the present invention, a route health check is performed by Ping from the monitoring node device installed in each network to the router in the opposite network, and a Ping response is sent from the router in the opposite network within a preset waiting time. If reception is not possible, the router requests the deletion of the information regarding the failed route from the router routing table, so that the failure of the relay network can be detected quickly.

  As described above, according to the present invention, even when using a relay network that cannot perform failure monitoring / route switching using a routing protocol between routers on the user side, the monitoring node device uses Ping to the router in the opposite network. When a health check is performed and a failure is detected, control is performed to delete the failed route from the router's routing table. Therefore, there is an effect that the failure can be detected quickly and high-speed route switching can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.
(Configuration example of the entire network)
FIG. 1 is a block diagram showing a configuration example of the entire network. As shown in the figure, the network NW1 and the network NW2 are connected by a router RT1 and a router RT2 via a redundant relay network 1 and relay network 2 such as a VPN or a dedicated line. In addition, the figure shows an example in which another network is connected to the relay network 1 and the relay network 2. The communication mode need not be 1: 1, and the monitoring node device according to the present invention can be applied to a large-scale network of a plurality of mesh types.

  A configuration example of the network NW1 is shown in FIG. As shown in the figure, the network NW1 includes nodes N11, N12, a router RT1, and a monitoring node device M1, which are realized by computers such as workstations and personal computers. An IP address (hereinafter referred to as an address) IP11 is provided for the interface on the network NW1 side of the router RT1, an address IP31 and an address IP41 are provided for the interface on the relay network side, and an address IP12 and an address IP13 are provided for the nodes N11 and N12, respectively. However, the address IP14 is set in the monitoring node apparatus M1.

  A configuration example of the network NW2 is shown in FIG. As shown in the figure, the network NW2 is composed of a node N21, a node N22, a router RT2, and a monitoring node device M2, which are realized by computers such as workstations and personal computers. The address on the network NW2 side of the router RT2 is the address IP21, the interface on the relay network side is the address IP32 and the address IP42, the nodes N21 and N22 are the address IP22 and the address IP23, respectively, and the monitoring node device M1 is the address IP24 is set.

(Configuration example of monitoring node device)
FIG. 4 shows an internal configuration example of the monitoring node devices M1 and M2. Referring to the drawing, the monitoring node device communicates with a storage unit 31 for storing various types of information, an input / output unit 32 for inputting and outputting various types of information, and an external device. It includes a communication unit 33 and a control unit 34 that has a CPU and the like and controls the entire apparatus, and these are connected by a bus.

  The storage unit 31 stores a route monitoring table 310 for managing route information held by the router, and a route monitoring / switching program 320. The route monitoring / switching program 320 monitors the normality of the route, and performs a process of outputting a command that disables use of the failed route in a router belonging to the same network as the monitoring node device when a failure occurs. It is a program for. The route monitoring / switching program 320 is executed by the control unit 34. When the control unit 34 executes the route monitoring / switching program 320, a function for sending a Ping to a router in the opposite network, a function for detecting a response to the sent Ping, and a spare route when a response cannot be detected A function to perform the process of switching to the current one is realized.

(Example of route monitoring table)
The route monitoring table 310 stored in the storage unit 31 holds information necessary for route monitoring. FIG. 5 shows an example of a route monitoring table of the network NW1 held in the storage unit of the monitoring node device M1.
In the route monitoring table shown in the figure, the “Ping destination address” in the first column indicates the address of the destination from which the Ping is sent from the monitoring node device M1, and the administrator inputs / outputs each monitoring target route. Set using the part. However, it is necessary to set the destination so that the Ping to be sent passes through the route to be monitored.

“Ping NG count (n)” in the second column indicates the sum of ping NG counts. This “PingNG count (n)” is incremented by “1” when the route monitoring Ping is NG, and is reset to 0 when Ping is OK.
“Allowable NG count (m)” in the third column indicates the sum of allowable PingNG counts set for each route. The “line state” in the fourth column indicates the state of the relay network. As this “line state”, “working”, “reserve”, and “failure” exist.

The “IP address of the router to be rewritten” in the fifth column indicates the IP address of the router RT1 whose route information is changed by the monitoring node device when a failure occurs. “Field information to be deleted (Next Hop)” in the sixth column indicates the IP address of the Next Hop to be deleted or added from the routing table of the router indicated by “IP address of the router to be rewritten” in the fifth column. ing.
A similar route monitoring table is also prepared for the network NW2, and is stored in the storage unit in the monitoring node device M2.

(Routing table)
FIG. 6 shows the contents of the routing table held by the router RT1. The routing table shown in the figure includes “destination network”, “Next Hop”, and “cost”. These pieces of routing information are either fixedly given by the administrator or generated by a routing protocol. When the router RT1 receives a request to delete routing information including an arbitrary “Next Hop” from the monitoring node device M1, the router RT1 instructs to delete the matching routing information.
Note that the routing table held by the router RT2 is also composed of “destination network”, “Next Hop”, and “cost”.

(Processing by route monitoring / switching program)
FIG. 7 is a flowchart showing processing by the route monitoring / switching program. This program is executed by the control unit in the monitoring node device at a preset cycle. Hereinafter, a processing example of a program executed by the control unit in the monitoring node device M1 provided in the network NW1 will be described.
The route monitoring / switching program is periodically started by the control unit.
First, when a start request is received in step F1, execution of step F2 is started, and Ping is transmitted to all Ping destination addresses currently in use with reference to the route management information in FIG. The Ping command is a command for confirming the normality of the network, and a route failure can be monitored by receiving a response to the response from the destination.

  By the way, there may be a case where a response to Ping cannot be detected within a predetermined response waiting time due to a network delay or the like. Also in this case, the route monitoring / switching program transmits Ping again according to an instruction from the control unit. Therefore, it is possible to detect a route failure early by shortening the Ping transmission interval. Specifically, the execution cycle of the route monitoring / switching program may be set short.

In step F3, if a Ping response is received within the response waiting time and the result is PingOK, the route has no fault and normality has been confirmed. In this case, in step F4, “PingNG count (n)” is reset to “0”, the process proceeds to step F9, and the processing by the program ends. On the other hand, if it is determined in step F3 that a response to Ping cannot be received within the response waiting time and the result is PingNG, the process proceeds to step F5.
In step F5, the “PingNG count (n)” of the route management information is compared with a preset “allowable NG count (m)”. If n <m, the process proceeds to step F8, and “1” is added to “PingNG count (n)” of the corresponding row. Then, it progresses to step F9 and the process by a program is complete | finished.

On the other hand, if n ≧ m in step F5, the contents of “IP address of router to be rewritten” and “field information to be deleted (Next Hop)” in the corresponding row are referred to in step F6. In step F7, the router having the IP address is instructed to delete the routing information corresponding to the “field information to be deleted (Next Hop)” in the routing table.
Note that if it is desired to delete the route immediately when m = 0 and PingNG occurs once, step F5 can be omitted and steps F3 → F6 can be performed. When the deletion process ends, the process proceeds to step F9, and the process by the program ends.

(Operation example of each part)
Next, an operation example of each part of the communication system having the above configuration will be described. Here, an example of operation in a network configuration including a total of two lines, one working route and one backup route, will be described. Here, as an example, the description will be made assuming that the allowable number of pings NG m = 3.
FIG. 8 shows a network configuration in this example. In this example, the network NW1 and the network NW2 are connected by two relay networks 1 and 2. As shown in the figure, processing for connecting the network NW1 and the network NW2 by the relay network 1 and the relay network 2 is performed by routers RT1 and RT2. Here, the relay network 1 is the working route, and the relay network 2 is the backup route.

  The network NW1 includes nodes N11 and N12, a router RT1, and a monitoring node device M1. An address IP11 is set for the interface on the network NW1 side of the router RT1, addresses IP31 and IP41 are set for the interface on the relay network side, addresses IP13 and IP14 are set for the nodes N11 and N12, respectively, and an address IP15 is set for the monitoring node device M1. .

The network NW2 includes nodes N21 and N22, a router RT2, and a monitoring node device M2. Address IP21 is set for the interface on the network NW2 side of the router RT2, addresses IP32 and IP42 are set for the interface on the relay network side, addresses IP23 and IP24 are set for the nodes N21 and N22, and address IP25 is set for the monitoring node device M1. .
9 to 12 show examples of the route information management table of the monitoring node devices M1 and M2 and the routing tables of the routers RT1 and RT2 before the occurrence of the failure in the communication system configured as described above.

Packets between the network NW1 and the network NW2 before the occurrence of the failure are transmitted / received using the relay network 1 according to the routing tables shown in FIGS. Each of the monitoring node devices M1 and M2 refers to the route failure management table, and follows the processing flow of the route monitoring / switching program shown in FIG. Monitor route failures.
If a route failure has not occurred, the process of steps F1->F2->F3->F4-> F9 in FIG. 7 is repeated. In this embodiment, in step F2, Ping is transmitted from the monitoring node device M1 to the destination address IP32 and from the monitoring node device M2 to the destination address IP42.

  Next, an operation when a failure occurs in the relay network 1 will be described. As shown in FIG. 13, when a route failure S occurs in the relay network 1, no response to Ping is returned from IP32 and IP31. For this reason, the process proceeds from step F1 to F2 to F3 to F5. Here, referring to “PingNG count (n)” in each route management information table, it is confirmed whether the NG count is the allowable NG count m = 3 or more. Immediately after the failure occurs, n = 0 and n ≧ m is not satisfied, so the process proceeds to step F8. In Step F8, “1” is added to “n” to set n = 1. Thereafter, the process proceeds to step F9, and the process ends (see FIGS. 14 and 15).

As shown in FIGS. 16 and 17, the contents of the routing table of each router are not changed.
Further, the monitoring flow is repeated, and the above steps F1 → F4 → F6 → F9 are repeated until n ≧ m (in this case, three times in total).
In the fourth flow, the process proceeds from step F1 → F2 → F3 → F5. Since n = 3 and n ≧ m is satisfied, the process proceeds to step F6. In step F6, “IP address of router to be rewritten” and “Ping destination address” are referred to in the corresponding row. Then, in step F7, route information (here, the first line) having “Next Hop” as IP32 from the routing table of router RT1, and route information (here, “Next Hop” as IP31 from the routing table of RT2) The first line) is deleted (see FIGS. 18 and 19).

  If the route information is lost by the above processing, the routers RT1 and RT2 select a route (here, the second line) via the relay network 2 which is the next priority route. This state is shown in FIG. Here, the first line of each route information table is changed from “active” to “failure”, and the second line is changed from “reserved” to “active” (see FIGS. 21 and 22). Thereby, the route to be monitored is changed.

(Modification)
In this embodiment, an example of a total of two lines, one working route and one backup route, has been described as a relay network between the network NW1 and the network NW2. However, in the case of a network configuration using a plurality of lines simultaneously, It is clear that the present monitoring node device can be applied even in the case of a network configuration in which there are no routes and only two or more working routes are used.

(Communication system monitoring method)
In the monitoring node device described above, the following monitoring method is realized. That is, the first network and the second network are connected by relaying between the routers provided in the first network and the second network through the working and backup paths. And a detection step for detecting a response to the Ping transmitted in the transmission step (corresponding to step F2 in FIG. 7). 7 and a switching step (corresponding to step F7 in FIG. 7) for performing a process of switching the backup path to the active route when the response cannot be detected in the detection step. The method is realized.
By adopting such a monitoring method, a failure in the relay network can be detected quickly.

(Communication system monitoring program)
The following program is stored in the storage unit in the monitoring node device described above. That is, the first network and the second network are connected by relaying between the routers provided in the first network and the second network through the working and backup paths. A transmission step for transmitting a Ping to a router in the opposite network (corresponding to step F2 in FIG. 7), and a detection step for detecting a response to the Ping transmitted in the transmission step ( 7) and a switching step (corresponding to step F7 in FIG. 7) for performing a process of switching the spare path to the current use when the response cannot be detected in the detection step. ing.
By executing such a program by a computer, it is possible to quickly detect a failure in the relay network.

  INDUSTRIAL APPLICABILITY The present invention can be used for monitoring a route failure in a communication system configured by connecting routers to each other by relaying them between a plurality of routes.

It is a block diagram which shows the structural example of the whole communication network. It is a block diagram which shows the structural example of network NW1. It is a block diagram which shows the structural example of network NW2. It is a block diagram which shows the example of an internal structure of a monitoring node apparatus. It is a figure which shows an example of the route monitoring table of network NW1 which the memory | storage part of the monitoring node apparatus M1 hold | maintains. It is a figure which shows the content of the routing table which router RT1 hold | maintains. It is a flowchart which shows the process by a route monitoring and switching program. It is a figure which shows the structural example of the communication network before a failure generation. It is a figure which shows the content before the failure generation of the routing table which router RT1 hold | maintains. It is a figure which shows the content before the failure generation of the routing table which router RT2 hold | maintains. It is a figure which shows the content before the failure generation of the route management information table which the monitoring node apparatus M1 hold | maintains. It is a figure which shows the content before the failure generation of the route management information table which the monitoring node apparatus M2 hold | maintains. It is a figure which shows the structural example of the communication network in the event of a failure occurrence. It is a figure which shows the content in the failure generation of the route management information table which the monitoring node apparatus M1 hold | maintains. It is a figure which shows the content in the failure generation of the route management information table which the monitoring node apparatus M2 hold | maintains. It is a figure which shows the content in the failure occurrence of the routing table which router RT1 hold | maintains. It is a figure which shows the content in the failure occurrence of the routing table which router RT2 hold | maintains. It is a figure which shows the content after the failure generation of the routing table which router RT1 hold | maintains. It is a figure which shows the content after the failure generation of the routing table which router RT2 hold | maintains. It is a figure which shows the structural example of the communication network after a failure generate | occur | produces. It is a figure which shows the content after the failure generation of the route management information table which the monitoring node apparatus M1 hold | maintains. It is a figure which shows the content after the failure generation of the route management information table which the monitoring node apparatus M2 hold | maintains.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Relay network 31 Memory | storage part 32 Input / output part 33 Communication part 34 Control part 310 Route monitoring table 320 Route monitoring / switching program M1, M2 Monitoring node device N11, N12, N21, N22 Node NW1, NW2 Network RT1, RT2 Router

Claims (3)

It is configured by connecting the first network and the second network by relaying between the routers provided in the first network and the second network through the working and backup routes. A monitoring node device used in a communication system,
A route monitoring table that holds information necessary to monitor a failure of the network, comprising at least the state of the network and a content that rewrites a routing table held by a router of the network to which the device belongs;
Sending means for sending Ping to the router of the opposite network;
Detecting means for detecting a response to Ping sent by the sending means;
It said detecting means viewed contains a switching unit performs a process of switching the path of the preliminary to the working if it can not detect the response,
The switching means refers to information necessary for monitoring a failure of the network held by the route monitoring table, and stores the contents of the routing table held by a router of the network to which the device belongs. A monitoring node device , which generates a deletion request for rewriting and outputs the deletion request, thereby performing a process of switching the spare path to an active one .   2. The monitoring node device according to claim 1, wherein the switching unit performs a process of switching the spare path to the active only when the number of times the response cannot be detected by the detection unit reaches a predetermined value. It is configured by connecting the first network and the second network by relaying between the routers provided in the first network and the second network through the working and backup routes. A communication system monitoring method comprising:
A holding step for holding information necessary for monitoring a failure of the network, comprising at least a state of the network and a content for rewriting a routing table held by a router of the network to which the device belongs;
A sending step for sending a Ping to a router in the opposite network;
A detecting step for detecting a response to the Ping sent in the sending step;
Wherein the preliminary path if it can not detect the response seen including a switching step performs the process of switching to the working in the detection step,
In the switching step, the contents of the routing table held by the router of the network to which the own device belongs are written with reference to the information necessary for monitoring the network failure held by the holding step. A method for monitoring a communication system , comprising: generating a deletion request for switching, and outputting the deletion request, thereby performing a process of switching the spare path to a current one .

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