JP2004146989A - Router system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a router system wherein a main router apparatus is replaced with a sub router apparatus, which can start direct communication with a communication terminal even on the occurrence of a line fault in a broadband network. <P>SOLUTION: The main router apparatus 55 detects whether or not a line fault takes place in an ATM network 73, changes the priority '255' having been set in advance into a priority '0' at least lower than the priority '100' of a backup router 61 when detecting the occurrence of the line fault in the ATM network 73, transmits an advertisement packet with the priority '0' attached thereto to the backup router apparatus 61, and the backup router apparatus 61 receives the advertisement packet from the main router apparatus 55 and starts communication with an ATM network 77 when a second priority having been set in advance is higher than the priority '0' attached to the received advertisement packet. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a router device, and more particularly, to a router device that forcibly switches a route from a main device to a backup device when a failure in a wide area network is detected.
[0002]
[Prior art]
Generally, an access router device (hereinafter, router device) having one LAN port equipped with a VRRP (Virtual Router Redundancy Protocol) function (RFC2388) and one WAN port for communicating with a wide area network is known. .
Two router devices are prepared, one router device is a main router device, the other router device is a backup router device, and the main router device and the backup router device are connected by a LAN line. When a personal computer PC is connected to the PC, a redundant configuration can be constructed.
[0003]
That is, in normal communication, as shown in FIG. 9, communication is performed by the main router device 103 connected to the wide area network 101, and the backup router device 105 connected to the same wide area network enters a standby state. I have.
Here, when a failure occurs in the LAN line 107 connected to the main router device 103 or the main body of the main router device 103, the communication by the backup router device 105 is performed by the VRRP function.
[0004]
In addition, one set of the main router device 103 and the backup router device 105 operating the VRRP function are used when a failure occurs in the device body, when a failure occurs in a LAN line, and each time a recovery from the failure occurs. This has the advantage that communication can be performed without changing the default gateway address set in the personal computer PC109 or the like.
[0005]
[Problems to be solved by the invention]
However, the conventional router device is configured such that the operation of only the VRRP function does not operate the VRRP function for a wide area network (hereinafter, referred to as a WAN line) such as an ATM line or an ISDN line.
For this reason, as shown in FIG. 10, when a failure occurs in the WAN line 111 connected to the main router 103, the main router 103 is switched to the backup router 105 to communicate with the personal computer PC109. There was a problem that it was not possible to continue.
[0006]
Further, in the conventional router, by operating the RIP function, OSPF function, OAM function, etc. on the WAN line, even if a failure occurs on the WAN line, the communication from the main router to the communication using the backup router can be performed. Can be switched.
However, in this case, as shown in FIG. 11, a packet transmitted from the personal computer PC 109 or the like is transmitted to the main router 103 once, and then indirectly transmitted from the main router 103 via the backup router 105. However, since the data is transmitted to the WAN line, the transfer efficiency is reduced. Also, at this time, if communication in the half-duplex mode is performed, a problem such as collision occurs, and there is a problem that a good communication state is not obtained.
[0007]
The present invention has been made in view of the above, and has as its object to start direct communication with a communication terminal by switching from a main router device to a sub router device even when a line failure occurs in a wide area network. And a router device capable of improving transfer efficiency.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 requires a main router device communicating with a first wide area network and a second wide area network different from the first wide area network. And a secondary router device that communicates according to the following, and configured to communicate via a LAN line between the communication terminal and the primary router device or the secondary router device, wherein the primary router device is a first router device. Fault detecting means for detecting whether or not a line failure has occurred in the wide area network, and when the occurrence of the line failure in the first wide area network has been detected, at least the first priority set in advance is set as a sub-address. Priority setting means for setting a third priority lower than the second priority of the router device, and transmission means for adding the set third priority to the advertisement packet and transmitting the advertisement packet to the sub router device The secondary router device has an advertisement packet from the primary router device. Start communication between the receiving means for receiving the advertisement packet and the second wide area network when the second priority set in advance is higher than the third priority added to the received advertisement packet. In the case where a line failure occurs in the first wide area network, the direct communication with the communication terminal is switched from the main router device to the sub router device.
[0009]
According to a second aspect of the present invention, in order to solve the above-mentioned problem, the secondary router device includes a transmission unit that adds a second priority set in advance to an advertisement packet and transmits the advertisement packet to the primary router device, The main router device includes recovery detecting means for detecting whether the line failure occurring in the first wide area network has been recovered, and a line detecting means for detecting that the line failure occurring in the first wide area network has been recovered. Priority setting means for setting the third priority set when a failure has occurred to at least a first priority higher than the second priority of the secondary router, and transmitting an advertisement packet from the secondary router Communication for starting communication between the receiving means for receiving and the first wide area network when the set first priority is higher than the second priority added to the received advertisement packet Starting means, and a first wide area network. If the generated line fault is restored, the gist of switching the direct communication with the communication terminal from the secondary router to the main router.
[0010]
According to a third aspect of the present invention, in order to solve the above-mentioned problem, the fault detecting means performs a fault detection using any one of an OAM loopback cell, an OSPF packet, and a RIP packet.
[0011]
According to a fourth aspect of the present invention, in order to solve the above problem, the recovery detecting means performs recovery detection using any one of an OAM loopback cell, an OSPF packet, and a RIP packet.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of a router device 11 according to an embodiment of the present invention.
[0013]
In FIG. 1, a CPU 13 for controlling the router device 11 includes a CPU core 15, a communication processor module 17, and a system interface unit 19.
The CPU core 15 provides functions such as execution of system software, control of a serial interface, control of a LAN interface, control of an ATM interface, address decoding, memory management function, refreshing of the SDRAM 23, and a watchdog timer function.
[0014]
In the serial interface, the communication processor module 17 generates a frame used on a serial line. The LAN interface performs a preamble and CRC generation process, a preamble deletion process, and a CRC check process. The ATM interface performs a process of dividing the variable-length packet information into cells and returning the cells to the original packet information.
[0015]
The system interface unit 19 performs activation, initialization, operation, protection, and bus control of the system.
Next, the flash ROM 21 is used to store program software and settings mounted on the router device 11, and has a capacity of, for example, 2 MB. The SDRAM (main memory) 23 is a main memory used by the CPU core 15, and has a capacity of, for example, 4 MB.
[0016]
The real-time clock 25 provides time information to the OS. The RS-232C transceiver 27 converts the signal into an electric signal used on a serial line. The Ethernet PHY 29 converts the signals into electrical signals to be used on the Ethernet line. The ATM PHY 31 converts the signal into an electric signal used on the ATM line.
[0017]
Next, the console port 33 has one serial interface (RS-232C) port. The LAN port 35 has a one-port LAN interface, and is connected to a personal computer PC or another router via a LAN line. The ATM port 37 has a one-port ATM interface and is connected to a WAN line via a WAN line.
[0018]
Next, with reference to FIG. 2, a description will be given of a packet format of an advertisement packet periodically communicated via a LAN line between LAN ports 35 provided in a plurality of router devices when using the VRRP function. This packet format has a basic length of 32 bits.
[0019]
Version indicates the version of the VRRP protocol, and its value is, for example, 2. Type is set to “1” for an advertisement packet, and an advertisement packet having an unknown type is discarded. The Virtual Rtr ID is a virtual router identifier and identifies a virtual router.
[0020]
Priority is the priority of transmission on the router device having the VRRP function, and the higher the value, the higher the priority. “255” is set in the router device having the virtual IP address. On the other hand, the router device that performs backup sets "1 to 254". Note that the default value of the router device that performs backup is “100”.
[0021]
Count IP Addrs indicates the number of IP addresses included in the advertisement packet. Auth Type indicates the type of authentication method used, "0" indicates no authentication, "1" indicates a simple text password, and "2" indicates an IP authentication header.
[0022]
Advert Int indicates a transmission interval of the advertisement packet, and a default value of a time interval (unit: second) of the advertisement packet is 1 second. Checksum indicates a checksum of the VRRP advertisement packet. IP Address indicates an IP address included in the virtual router device, and the number of IP addresses is set to “Count IP Addresses”. "Authentication Data" indicates an authentication character string used in simple text authentication.
[0023]
Next, a communication system including two router devices according to the present embodiment will be described with reference to FIG.
As shown in FIG. 3, a personal computer PC 51 is connected to a main router 55 and a backup router 61 via a LAN line 53. The main router device 55 and the backup router device 61 have the same basic configuration as the router device 11 shown in FIG. 1, but in this system, different reference numerals are used to distinguish them.
[0024]
A personal computer PC51 is connected to the main router device 55 via a LAN line 53, and a WAN network 59 is connected via a WAN line 57. Similarly, a personal computer PC 51 is connected to the backup router device 61 via a LAN line 53, and a WAN network 65 is connected via a WAN line 63.
[0025]
FIG. 3 shows a normal operation state, in which communication among the personal computer PC 51, the LAN line 53, the main router device 55, the WAN line 57, and the WAN network 59 is in a normal state. Therefore, in the state shown in FIG. 3, the main router 55 is in the main state, and the backup router 61 is in the backup state.
[0026]
Next, FIG. 4 is a diagram showing that the communication system shown in FIG. 3 has shifted from a normal state to an abnormal state.
As shown in FIG. 4, when a failure occurs in the WAN line 57 which communicates between the main router 55 and the WAN network 59, the main router 55 shifts from the main state to the backup state, and The router device 61 shifts from the backup state to the main state.
As a result, communication is performed among the personal computer PC 51, the LAN line 53, the backup router device 61, the WAN line 63, and the WAN network 65.
[0027]
A feature of the present invention is that, when the main router 55 detects a failure occurring in the WAN line 57 by focusing on a failure occurring in the WAN line 57, the VRRP function instantaneously connects the backup router 61 to the personal computer PC51. It is to operate to switch to direct communication.
[0028]
(Example 1)
Next, an embodiment of the communication system shown in FIGS. 3 and 4 will be described with reference to the communication system shown in FIGS.
FIG. 5 is a diagram showing that the communication system is in a normal state.
As shown in FIG. 5, an ATM network 73 is connected to the main router device 55 via an ATM line 71. Similarly, an ATM network 77 is connected to the backup router 61 via an ATM line 75. Note that an ISDN line or an ISDN network may be used instead of the ATM line 75 and the ATM network 77.
[0029]
FIG. 5 shows a normal operation state, in which communication among the personal computer PC 51, the LAN line 53, the main router device 55, the ATM line 71, and the ATM network 73 is in a normal state. Therefore, in the state shown in FIG. 5, the main router 55 is in the main state, and the backup router 61 is in the backup state.
[0030]
Next, FIG. 6 is a diagram showing that the communication system shown in FIG. 5 has shifted from a normal state to an abnormal state.
As shown in FIG. 6, when a failure occurs in the ATM line 71 which communicates between the main router 55 and the ATM network 73, the main router 55 shifts from the main state to the backup state, and The router device 61 shifts from the backup state to the main state.
[0031]
As a result, communication is performed among the personal computer PC 51, the LAN line 53, the backup router device 61, the ATM line 75, and the ATM network 77.
[0032]
The feature of the present embodiment is that, when the main router 55 detects a failure occurring in the ATM line 71 by focusing on a failure occurring in the ATM line 71, the backup router device 61 and the personal computer PC51 are instantaneously connected by the VRRP function. It operates to switch to direct communication.
[0033]
Hereinafter, the characteristic operation of the router device according to the present embodiment will be described in detail with reference to the flowcharts shown in FIGS. In addition. This flowchart is operated by a control program stored in a flash ROM 21 provided in the router device 11 as shown in FIG.
[0034]
(1) When a line failure occurs
It is assumed that normal communication is currently being performed between the personal computer PC 51 and the ATM network 73 via the main router device 55. In normal communication, a packet transmitted from the personal computer PC51 is transmitted from the ATM line 71 to the ATM network 73 via the main router device 55.
[0035]
The positions of the main router device 55 and the backup router device 61 are determined by priorities set in advance for each router device. These priorities are given from 1 to 255, and the higher the value, the higher the priority. Specifically, in a normal state, the priority of the main router 55 is set to, for example, “255”, and the priority of the backup router 61 is set to, for example, “100”.
[0036]
Here, in step S100, the main router device 55 transmits the advertisement packet with the priority added to the backup router device 61 via the LAN line 53. On the other hand, in step S200, the backup router device 61 receives the advertisement packet via the LAN line 53.
[0037]
Next, in step S105, the main router device 55 detects whether a line failure has occurred in the ATM line 71. Specifically, the main router 55 transmits an OAM loopback cell to the ATM line 71 and waits for a response cell from the ATM line 71. At this time, if the main router device 55 cannot receive a response cell from the ATM line 71 within a predetermined time, it means that the failure has occurred in the ATM line 71. If no line failure has occurred in the ATM line 71, the process returns to step S100, and this process is repeated.
[0038]
On the other hand, if the OAM loopback cell transmitted / received to / from the ATM network 73 via the ATM line 71 cannot be received due to the line failure, the main router device recognizes that the ATM line 71 has failed and 55 is virtually changed to a state in which a device failure has occurred. Therefore, the main router 55 proceeds to step S110, and changes the priority of the main router 55 from “255” to “0”. That is, the priority of the main router 55 is set to a value lower than the priority set in the backup router.
[0039]
In the VRRP function, when the priority of the main router 55 becomes “0”, the main router 55 loses its qualification and switches to the backup router 61 immediately.
[0040]
Next, in step S115, the main router device 55 transmits the advertisement packet whose priority field is set to “0” to the backup router device 61 via the LAN line 53.
[0041]
On the other hand, in step S205, the backup router device 61 receives this advertisement packet, and proceeds to step S210. In step S210, it is determined whether or not the priority field value in the received advertisement packet is lower than the priority of the backup router device 61.
[0042]
Here, if the priority of the main router 55 is higher than the priority of the backup router, the backup router 61 returns to step S200 and repeats this process.
[0043]
On the other hand, if the priority “0” of the main router 55 is lower than the priority “100” of the backup router 61, it is recognized that a virtual device failure has occurred in the main router 55, and the process proceeds to step S215. move on.
[0044]
Next, the backup router 61 switches the communication to the backup router 61 in step S215. As a result, communication is performed directly between the personal computer PC 51 and the ATM network 77 via the backup router 61.
[0045]
Here, in step S220, the backup router 61 transmits the advertisement packet with the priority added to the main router 55 via the LAN line 53. On the other hand, in step S120, the main router device 55 receives the advertisement packet via the LAN line 53.
[0046]
As a result, even when a line failure occurs in a WAN network such as an ATM network, the priority of the main router device can be set lower than that of the backup router device using the VRRP function to be notified. Can be transmitted directly to the backup router device, and direct communication with the personal computer PC is started by the backup router device with high priority, so that the transfer efficiency can be improved.
[0047]
Further, when a line failure occurs in a WAN network such as an ATM network, the main router switches to a reception state, so that even when communication is performed in a half-duplex mode on a LAN line, collision occurs due to simultaneous transmission of data. Can be reduced.
Further, when a line failure occurs in a WAN network such as an ATM network, route switching is performed by the VRRP function, so that it is faster than route switching by the RIP function or the OSPF function.
[0048]
(2) When recovering from line failure
It is assumed that communication is currently being performed between the personal computer PC51 and the ATM network 77 via the backup router device 61.
Then, in step S250, the backup router device 61 transmits the advertisement packet with the priority added to the main router device 55 via the LAN line 53. On the other hand, in step S150, the main router device 55 receives the advertisement packet via the LAN line 53.
[0049]
Next, in step S155, the main router 55 detects whether or not the ATM line 71 has recovered from the line failure. Specifically, the main router device 55 transmits an OAM loopback cell to the ATM line 71 and waits for a response cell from the ATM line 71. At this time, if the main router device 55 can receive the response cell from the ATM line 71 within a certain period of time, it means that it has detected that the line failure occurring on the ATM line 71 has been recovered. If the line failure that has occurred on the ATM line 71 has not been recovered, the process returns to step S150, and this process is repeated.
[0050]
On the other hand, when the OAM loopback cell transmitted / received to / from the ATM network 73 via the ATM line 71 can be received by recovery from the line failure, the line failure occurring on the ATM line 71 is recovered. And the main router 55 is brought into a normal state. Therefore, the main router 55 proceeds to step S160, and changes the priority of the main router 55 from “0” to “255”. That is, the priority of the main router 55 is set to a value higher than the priority set in the backup router.
[0051]
Then, in step S255, the backup router device 61 transmits the advertisement packet with the priority added to the main router device 55 via the LAN line 53. On the other hand, the main router device 55 receives the advertisement packet via the LAN line 53 in step S165.
[0052]
Next, in step S170, the main router 55 determines whether the priority field value in the received advertisement packet is lower than the priority of the main router 55.
Here, when the priority of the main router 55 is lower than the priority of the backup router 61, the main router 55 returns to step S150 and repeats this process.
[0053]
On the other hand, if the priority “255” of the main router 55 is higher than the priority “100” of the backup router 61, it is recognized that the virtual device failure occurring in the main router 55 has been recovered. The process proceeds to step S175.
Next, the main router 55 switches to communication by the main router 55 in step S175. As a result, normal communication is directly performed between the personal computer PC 51 and the ATM network 73 via the main router device 55.
[0054]
Here, in step S180, the main router device 55 transmits the advertisement packet with the priority added to the backup router device 61 via the LAN line 53. On the other hand, in step S260, the backup router device 61 receives the advertisement packet via the LAN line 53.
[0055]
As a result, even when a line failure that has occurred in a WAN such as an ATM network is recovered, the priority of the main router can be set higher than that of the backup router by using the VRRP function, thereby notifying the personal computer PC or the like. Can directly transmit the packet to the main router device, and direct communication with the personal computer PC is started by the high-priority main router device, so that transfer efficiency can be improved.
[0056]
Also, when a line failure occurs in a WAN network such as an ATM network, the backup router switches to a reception state, so that even when communication is performed in half-duplex mode with a LAN line, collision occurs due to simultaneous transmission of data. Can be reduced.
Further, when a line failure occurs in a WAN network such as an ATM network, route switching is performed by the VRRP function, so that it is faster than route switching by the RIP function or the OSPF function.
[0057]
(Example 2)
In the first embodiment described above, the detection of whether a line failure has occurred in the ATM line 71 and the detection of whether or not the ATM line 71 has recovered from the line failure are performed by the OAM loopback cell as described above. To detect whether a response cell has been received from the ATM line 71 within a predetermined time. However, the present invention can use, for example, an OSPF packet or a RIP packet instead of using the OAM loopback cell.
[0058]
The OSPF (Open Shortest Path First) function is a routing information exchange protocol for determining an optimal route for transmitting a packet. The route selection of the packet on the Internet network is performed by the IP address on each gateway. At this time, the route information necessary for determining the route is not the IP address itself, but is exchanged between gateways according to an application level protocol using the IP address. The occurrence of a line failure can be detected by confirming the presence or absence of the path information using the OSPF function.
[0059]
Next, a RIP (Routing Information Protocol) function is used for exchanging packets related to the network address, the number of POPs, and the delay time between the inquiring side and the responding side to hold optimal communication path information. This is a function, and the occurrence of a line failure can be detected by confirming the presence or absence of response information using the RIP function.
[0060]
As described above, by using the dynamic routing such as the RIP function and the OSPF function, the master router device can detect the occurrence of the failure in the ATM line by the RIP function and the OSPF function. In this case as well, the main router 55 may be placed in a virtual device failure state, and the communication may be switched to the communication via the backup router 61 by the VRRP function.
[0061]
【The invention's effect】
According to the first aspect of the present invention, even when a line failure occurs in the wide area network, the priority of the main router device can be set lower than that of the sub router device, so that the packet from the communication terminal or the like can be directly transmitted. Since the direct communication with the communication terminal is started by the high-priority sub-router device, the transfer efficiency can be improved.
[0062]
Further, when a line failure occurs in the wide area network, the main router is switched to the reception state, so that it is possible to reduce the occurrence of collision due to simultaneous transmission of data even when communicating with the LAN line in the half-duplex mode. it can.
[0063]
According to the second aspect of the present invention, even when the line failure occurred in the wide area network is recovered, the priority can be set to the main router device higher than that of the sub router device and the notification can be performed. Can be transmitted directly to the main router device, and direct communication by the main router device with a higher priority is started with the communication terminal, so that transfer efficiency can be improved.
[0064]
Further, when a line failure occurs in the wide area network, the sub router device is switched to the reception state, so that it is possible to reduce the occurrence of collision due to the simultaneous transmission of data even when communicating with the LAN line in the half-duplex mode. it can.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a router device 11 according to an embodiment of the present invention.
FIG. 2 is a diagram showing a packet format of an advertisement packet.
FIG. 3 is a diagram showing a communication system including two router devices according to the present embodiment.
FIG. 4 is a diagram showing that the communication system has transitioned from a normal state to an abnormal state.
FIG. 5 is a diagram showing that the communication system is in a normal state.
FIG. 6 is a diagram showing that the communication system has transitioned from a normal state to an abnormal state.
FIG. 7 is a flowchart for describing in detail a characteristic operation of the router device according to the present embodiment when a line failure occurs.
FIG. 8 is a flowchart for describing in detail a characteristic operation of the router device according to the present embodiment when a line failure is recovered.
FIG. 9 is a diagram showing that a conventional communication system has shifted from a normal state to an abnormal state.
FIG. 10 is a diagram showing a state in which a personal computer PC cannot directly communicate with a WAN line via a backup router device when a line failure occurs in a conventional communication system.
FIG. 11 is a diagram showing a state in which a personal computer PC once communicates with a WAN line via a main router device and then via a backup router device when a line failure occurs in a conventional communication system.
[Explanation of symbols]
11 Router device
13 CPU
15 CPU core
17 Communication Processor Module
19 System interface unit
21 Flash ROM
23 SDRAM
25 Real-time clock
27 RS-232C transceiver
29 Ethernet PHY
31 ATM PHY
33 Console port
35 LAN port
37 ATM port
51 Personal computer PC
53 LAN line
55 Main router device
57,63 WAN line
59,65 WAN network
61 Backup router device
71,75 ATM line
73,77 ATM line

Claims (4)

A main router device communicating with the first wide area network;
A secondary router device that communicates with a second wide area network different from the first wide area network as needed;
A communication system configured to communicate between a communication terminal and a main router device or a sub router device via a LAN line,
The main router device is
Failure detection means for detecting whether a line failure has occurred in the first wide area network;
When it is detected that a line failure has occurred in the first wide area network, the previously set first priority is set to at least a third priority lower than the second priority of the secondary router. Priority setting means;
Transmitting means for adding the set third priority to the advertisement packet and transmitting the advertisement packet to the sub router device,
The secondary router device is
Receiving means for receiving an advertisement packet from the main router device;
Communication starting means for starting communication with the second wide area network when the second priority set in advance is higher than the third priority added to the received advertisement packet. ,
A router device for switching direct communication with a communication terminal from a main router device to a sub router device when a line failure occurs in a first wide area network. The secondary router device,
Transmission means for adding a second priority set in advance to the advertisement packet and transmitting the advertisement packet to the main router,
The main router device,
Restoration detection means for detecting whether or not the line failure occurred in the first wide area network has been restored;
When it is detected that the line failure that has occurred in the first wide area network is recovered, the third priority set when the line failure occurs is at least higher than the second priority of the secondary router device. Priority setting means for setting the first priority;
Receiving means for receiving an advertisement packet from the secondary router device;
Communication starting means for starting communication with the first wide area network when the set first priority is higher than the second priority added to the received advertisement packet,
A router device for switching direct communication with a communication terminal from a sub router device to a main router device when a line failure occurred in a first wide area network is restored. The failure detecting means,
The router device according to claim 1, wherein failure detection is performed using any one of an OAM loopback cell, an OSPF packet, and a RIP packet. The recovery detecting means,
The router device according to claim 2, wherein recovery detection is performed using any one of an OAM loopback cell, an OSPF packet, and a RIP packet.

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