JP6710170B2 - Communication device, communication method, and communication processing program - Google Patents

Description

Embodiments of the present invention relate to a communication device, a communication method, and a communication processing program.

When constructing a wide area network, a method of constructing a combination of a plurality of networks according to the requirements of the network is widespread.
For example, when providing a wide area Ethernet (registered trademark) service, instead of constructing a network using only Ethernet, it is possible to construct a network by connecting a plurality of Ethernet networks with MPLS (Multi Protocol Label Switching) networks. , Ethernet is widely used in methods that enable traffic engineering that is difficult to achieve.

When connecting multiple Ethernet networks by MPLS network as in the above example, communication between networks is realized by converting the packet format of MPLS and Ethernet by the device at the boundary between MPLS and Ethernet. ..

Packets based on Ethernet appear to be transmitted and received between users using the wide area Ethernet service, but packets can be transmitted and received based on MPLS within the network.

In such a network, when a failure occurs in the network, the detouring method of the failed part depends on the detouring technique of the network at the failed part.
For example, in the case of a failure in a network constructed by Ethernet, it is possible to continue communication by bypassing the failure point by using a path switching technology at the time of failure such as ERP (Ethernet (registered trademark) Ring Protocol). It is possible.

In addition, as a method of bypassing a failure point used in an IP (Internet Protocol) network or the like, a routing protocol is operated in the network, and when a failure is detected, a route for bypassing the failure point and recovering communication is recalculated. Although there is a method, the method has a problem in that the recalculation time becomes long depending on the size of the network, and thus the communication interruption time becomes long until the communication is restored.

Therefore, there is a technique called FRR (Fast ReRoute) in order to shorten the communication disconnection time caused by the recalculation of the route by the above-mentioned routing protocol (Non-patent Document 1).

This technology switches routes at high speed after detecting a fault by presetting a route (preliminary route) to return to the normal route by making a detour to a place where a fault may occur. It is a technology.
By using this technique to set a route that can bypass all communication devices in the network, the route can be switched at high speed even if any part of the network fails.

Fast Reroute Extensions to RSVP-TE for LSP Tunnels, Internet <https://tools.ietf.org/html/rfc4090>, [February 7, 2017 Search]

However, when a device located at the boundary of the network fails, a backup route across the failed device cannot be set because the detouring method of the failed part is different in each network that crosses the boundary.
If a device located at the boundary of the network fails, in order to restore communication, as described above, use the routing protocol in the network, recalculate the route, or use the network operation tool. , There is a method to set a new communication path, but the problem is that the time until communication recovery is prolonged.

An object of the present invention is to provide a communication device, a communication method, and a communication processing program capable of shortening the time for setting a bypass communication path with respect to a failure of a device existing at the boundary of a network.

In order to achieve the above object, a first aspect of a communication device according to an embodiment of the present invention is to provide a normal path used for normal communication for redundancy against a network failure, and a normal path used when the normal path fails. A backup route used for communication is preset, and when the normal route fails, the main network that switches the communication route to be used to the paired backup route to restore communication, and the network connected to the main network A communication device used as a boundary device for performing device redundancy operation, wherein a plurality of devices are arranged at a boundary with an adjacent network that performs communication, and (1) when a packet is received from the network, Own device information used to determine whether or not the destination is the own device, and (2) another boundary device forming a pair of device redundancy with the own device as the destination and passing through the own device by the backup route. A storage unit that stores a destination information table that records a backup route identifier that is destination information that is added to the packet, and the own device that is recorded in the destination information table when the packet is received from the network. Based on the information and the backup route identifier, the received packet, the destination network determination unit that determines whether the packet is a packet to be transmitted from the own device to the adjacent network, and the destination network determination unit, The destination information added to the packet determined to be the packet to be transmitted to the adjacent network is deleted, and after this deletion, which of the adjacent networks the own device is connected to the received packet is A packet format conversion unit that selects whether to transmit to the network, converts the format of the received packet into a format that is compatible with the selected adjacent network, and transmits the packet whose format has been converted by the packet format conversion unit And an adjacent network transmission function unit that determines the network connection port to be used for transmitting the converted packet to the determined network connection port.

A second aspect of the communication device according to the exemplary embodiment of the present invention is the information of the destination information table regarding the packet determined by the destination network determination unit to be the packet to be transmitted to the adjacent network in the first aspect. And a device that further includes a duplicate packet discard unit that determines whether to transmit or discard the packet to the adjacent network according to whether the received packet is treated as a multicast in the adjacent network. provide.

The first aspect of the communication method in the embodiment of the present invention is that a normal route used for normal communication and a backup route used for communication when the normal route fails are provided in advance for redundancy against network failure. When the normal path is set and the normal path fails, the main network that switches the communication path to be used to the pair of the backup paths to restore communication, and the adjacent network that communicates with each other by connecting to the main network A method applied to a communication device, wherein a plurality of devices are arranged at a boundary and used as a boundary device for performing device redundancy operation, wherein the communication device receives the packet when (1) a packet is received from the network. Self-device information used to determine whether or not the destination of the packet is the self-device, and (2) another boundary device forming a pair of self-device redundancy with the self-device is the destination, and the self-device is specified by the backup route. It has a storage unit that stores a destination information table that records the backup route identifier that is the destination information given to the passing packet, and is recorded in the destination information table when the packet is received from the network. On the basis of the own device information and the backup route identifier, it is determined whether the received packet is a packet to be transmitted from the own device to the adjacent network, and the packet is to be transmitted to the adjacent network. The destination information given to the determined packet is deleted, and after this deletion, which of the adjacent networks to which the received packet is connected is selected to which adjacent network to transmit, The format of the received packet is converted into a packet format suitable for the selected adjacent network, the network connection port used for transmission is determined for the packet with the converted format, and the converted packet is determined as the network. Provide a way to send to the connection port.

In a second aspect of the communication method according to the exemplary embodiment of the present invention, in the first aspect, regarding a packet determined to be a packet to be transmitted to the adjacent network, information of the destination information table and the received packet are A method of determining whether to transmit or discard the packet to the adjacent network according to information indicating whether or not the packet is treated as multicast in the adjacent network is provided.

An aspect of a communication processing program according to an embodiment of the present invention is a program used for a computer that operates as a part of the communication device according to the first aspect, wherein the computer includes the storage unit, the destination network determination unit, and A program for operating as a packet format conversion unit and the adjacent network transmission function unit is provided.

According to the present invention, it becomes possible to shorten the time for setting a bypass communication path for a failure of a device existing at the boundary of a network.

The figure which shows an example of operation|movement which communicates using different networks. The figure which shows an example of the operation|movement which recovers communication by the route recalculation by a routing protocol at the time of a boundary device failure. The figure which shows an example of the operation|movement which recovers communication by the route recalculation by a routing protocol at the time of a boundary device failure. The figure explaining an example of operation at the time of using FRR which is a high-speed path switching function at the time of a failure. FIG. 6 is a diagram showing an example of an operation of transmitting a packet passing through a backup route to a failed boundary device from a device having a redundant configuration with the failed boundary device when the boundary device fails in an embodiment of the present invention. FIG. 6 is a diagram showing an example of an operation of transmitting a packet, which is routed through a backup route to a device having a redundant configuration with the fault boundary device, from the device having the redundant configuration with the fault boundary device when the border device fails in an embodiment of the present invention. FIG. 6 is a diagram showing an example of an operation of performing multicast using different networks according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of a problem in which a multicast packet is transmitted in duplicate when a boundary device fails in an embodiment of the present invention. FIG. 6 is a diagram showing an example of an operation of preventing duplicate transmission of a multicast packet when a boundary device fails in an embodiment of the present invention. The figure which shows an example of the network form for describing one Embodiment of this invention. The figure which shows an example of operation|movement when a boundary device breaks down by the redundant structure by the number of the boundary devices exceeding 2 in one Embodiment of this invention. FIG. 4 is a diagram showing an example of a configuration of a functional unit for transmitting a packet that passes through a backup route to a failed boundary device from a device having a redundant configuration with the failed boundary device when the boundary device fails in an embodiment of the present invention. The figure which shows an example of the determination flow of a transmission destination network determination part in one Embodiment of this invention. According to an embodiment of the present invention, in the case of a boundary device failure, a configuration of a functional unit for transmitting a packet passing through a backup route addressed to a device in a redundant configuration with the failure boundary device from a device in the redundant configuration with the failure boundary device The figure which shows an example. FIG. 3 is a diagram showing an example of a configuration of a functional unit for preventing duplicate transmission of a multicast packet when a boundary device fails in an embodiment of the present invention. The figure which shows an example of the discarding flow of the duplicate packet discarding part in one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments.
Here, in order to facilitate understanding of the present invention, in the case where a communication device located at the boundary of a network (hereinafter, sometimes referred to as a boundary device) fails according to the conventional technique, the failed boundary device is An example of detouring and continuing communication will be described.
When the boundary device fails, it is necessary to bypass the failed device and continue communication. In order to switch a communication path (hereinafter sometimes simply referred to as a path) at a high speed when a device fails, it is necessary to use FRR to preset a backup route across each device.
An operation for recovering communication by redesigning a route when a boundary device fails will be described with reference to FIGS. FIG. 1 is a diagram illustrating an example of an operation of performing communication using different networks. 2 and 3 are diagrams showing an example of an operation for recovering communication by recalculating a route by a routing protocol when a boundary device fails.
For example, as shown in FIG. 1, a first boundary device 10 (hereinafter sometimes referred to as boundary device A), a second boundary device 20 (hereinafter sometimes referred to as boundary device B), which have a redundant configuration, and redundancy. A third boundary device 50 (hereinafter, sometimes referred to as boundary device E), a fourth boundary device 60 (hereinafter, sometimes referred to as boundary device F), and a first relay device 30 (hereinafter, relay) having the configuration. Device C), second relay device 40 (hereinafter also referred to as relay device D), and first opposite device 70 belonging to a network different from the network configured by devices AF. A network configured by (hereinafter, sometimes referred to as a device G or a counter device G) will be described. The relay device is a device located inside the network to which the boundary device belongs.

The boundary device A has a network connection port (hereinafter, also referred to as a connection port or a port) A1, a port A2, and a port A3. The boundary device B has a port B1, a port B2, and a port B3. The relay device C has a port C1, a port C2, and a port C3. The relay device D has a port D1, a port D2, and a port D3. The boundary device E has a port E1, a port E2, and a port E3. The boundary device F has a port F1, a port F2, and a port F3. The device G has a port G1 and a port G2.
The port A1 is communicatively connected to the port G1. The port A2 is communicatively connected to the port B2. The port A3 is communicatively connected to the port C1.
The port B1 is communicatively connected to the port G2. The port B3 is communicatively connected to the port D1.
The port C2 is communicatively connected to the port D2. The port C3 is communicatively connected to the port E1.
The port D3 is communicatively connected to the port F1.
The port E2 is communicatively connected to the port F2. The ports E3 and F3 receive packets from the outside.

As shown in FIG. 1, the boundary device E has a transfer table (destination information table) E4. The transfer table E4 defines the destination device of the packet (here, the opposite device G) and the destination boundary device (here, the boundary device A).

Further, as shown in FIG. 1, the boundary device F has a transfer table F4. The transfer table F4 defines the destination device (here, the opposite device G) of the packet and the destination boundary device (here, the boundary device B). The various transfer tables are realized as a storage unit by storing them in a storage device such as a non-volatile memory.

The boundary device E receives the packet (Data A) addressed to the device G. The boundary device F also receives the packet (Data B) addressed to the device G.
Based on the information of the destination device (device G) and the information of the destination boundary device (before the failure detection) (boundary device A) of the transfer table E4, the boundary device E assigns the destination of the packet addressed to the device G to the destination of the boundary device A. The packet is added and the packet is transmitted to the boundary device A via the relay device C.
Also, the boundary device F assigns the destination addressed to the boundary device B to the packet addressed to the device G based on the information about the destination device (device G) and the information about the destination boundary device (boundary device B) in the transfer table F4. , The packet is transmitted to the boundary device B via the relay device D.
The boundary devices A and B, which have received the packet, delete the destination addressed to itself, which is given to this packet, and transmit the packet to the device G.

In the network described with reference to FIG. 1, when the boundary device A fails, the boundary device E needs to change the destination of the packet transmitted to the boundary device A to the boundary device B and continue the transmission. is there.

For example, as shown in FIGS. 2 and 3, consider the network described in FIG. 1 and the network in which the boundary device A has a failure.
The boundary device B, which has detected the failure of the boundary device A, transmits a destination change request by a routing protocol to the boundary devices E and F to boundary devices other than itself.
Upon receiving the destination change request, the boundary device E changes the information of the destination boundary device in the transfer table E4 from the boundary device A before the failure detection to the boundary device B after the failure detection, and as shown in FIG. The packet addressed to the device G is transmitted via the boundary device B. In this way, it is possible to continue transmission when the boundary device A fails.

However, when such a technique is used, the processing time required for the destination change request of the boundary device B becomes longer depending on the scale of the network, and therefore the time from the communication interruption due to the failure to the recovery becomes longer.

Next, with reference to FIG. 4, an example of a problem in which a backup path cannot be set when a boundary device fails will be described. FIG. 4 is a diagram illustrating an example of an operation when the FRR that is the high-speed path switching function at the time of failure is used.
For example, as shown in FIG. 4, (1) border device A and border device B having a redundant configuration, (2) border device E and border device F having a redundant configuration, (3) relay device C, (4) relay device. D, (5) a device G belonging to a network different from the network configured by the devices A to F, and (6) a backup route H used when the relay device C detects a failure, and , Consider a network in which boundary device A has failed.
In the network having the backup route H as shown in FIG. 4, the relay device E has a transfer table C4 that defines the destination of the packet. The transfer table C4 defines the destination device of the packet (here, the boundary device A).

The boundary devices E and F receive the packet addressed to the device G.
Similar to the example shown in FIG. 1, the boundary device E is addressed to the device G based on the information of the destination device (device G) and the information of the destination boundary device (before failure detection) (boundary device A) of the transfer table E4. The destination of the boundary device A is added to the packet of No. 1, and the packet is transmitted to the boundary device A of the destination defined in the transfer table C4 via the relay device C.
Further, the boundary device F sends the packet addressed to the device G to the boundary device B based on the information about the destination device (device G) and the information about the destination boundary device (before the failure detection) (boundary device B) in the transfer table F4. The destination is given and the packet is transmitted to the boundary device B via the relay device D.

In order to bypass the route due to the failure of the boundary device A, it is necessary to set a backup route H from the relay device C to the device G, but the network between the boundary devices A and B and the device G is a boundary. Since it is different from the network to which the devices A to F belong, the FRR cannot set the backup route from the relay device C to the device G.

It is possible to set a backup route from the relay device C to the boundary device A passing through the relay device D and the boundary device B. However, if the boundary device A fails, even if the backup route is used, Since the boundary device A, which is a device, has a failure, it is not possible to set a route that bypasses the failure location.
As described above, when the existing technology is used, there is a problem that when the boundary device fails, the communication interruption time becomes long depending on the network to which the boundary device belongs.
Therefore, the present invention provides a method of recovering communication without waiting for the recalculation time of the routing protocol when a failure occurs in a boundary device located at the boundary of different networks.

The present invention provides a communication device that, in a redundant border device, refers to a backup route identifier and, when a packet with a backup route identifier is received, sends a packet to a destination even if it is not addressed to itself. ..

The operation when the present invention is used will be described with reference to FIG. FIG. 5 is a diagram showing an example of an operation of transmitting a packet passing through a backup route to a failed boundary device from a device having a redundant configuration with the failed boundary device when the boundary device fails in one embodiment of the present invention. ..
For example, as shown in FIG. 5, (1) border device A and border device B having a redundant configuration, (2) border device E and border device F having a redundant configuration, (3) relay device C, (4) relay A device D, (5) a device G belonging to a network different from the network configured by the devices A to F, and (6) a backup route H to the boundary device A used when the relay device C detects a failure. Consider a network that has the boundary device A and is in a state of failure.

When the relay device C detects the failure of the boundary device A, the relay device C changes the information of the destination device in the transfer table C4 from the boundary device A before the failure detection to the backup route H, and the backup route H to the boundary device A. To send the packet.

The boundary device B determines the destination information of the packet received from the relay device C and the presence/absence of the backup route identifier, and even if the packet is not addressed to itself, if this packet is provided with the backup route identifier, the boundary device B Instead of transmitting to the device A, the boundary device B transmits to the device G.
If the destination information of the received packet is addressed to itself, the boundary device B transmits this packet to the device G.

According to the present invention, when the boundary device A fails, the communication can be restored without waiting for the recalculation of the route by the routing protocol, which has been conventionally performed, so that the communication disconnection time can be shortened.

In addition, in the operation described with reference to FIG. 5, although the backup route is set between the relay device C and the boundary device A, the boundary device B transmits the packet to the device G. The same operation is performed even if the backup route from the boundary device to the boundary device B is set.

However, in the FRR, which is an existing function, the backup route can only be set so as to return to the normal route, so a function capable of setting the route of the backup route is required.
The setting for not returning the route of the backup route to the normal system will be described with reference to FIG. FIG. 6 is an example of an operation of transmitting a packet, which passes through a protection route to a device having a redundant configuration with a fault boundary device, from a device having the redundant border device and a device having a redundant configuration when the border device fails in one embodiment of the invention. FIG.
For example, as shown in FIG. 6, (1) border device A and border device B having a redundant configuration, (2) border device E and border device F having a redundant configuration, (3) relay device C, (4) relay A device D, (5) a device G belonging to a network different from the network configured by the devices A to F, and (6) a backup route I for the boundary device B used when the relay device C detects a failure. Consider a network that has the boundary device A and is in a state of failure. The backup route I is a route whose destination is different from that of the backup route H destined for the boundary device A shown in FIG.
Similar to the network having the backup route H, in the network having the backup route H as shown in FIG. 6, the relay device E has the transfer table C4.

When the relay device C detects the failure of the boundary device A, the relay device C changes the information of the destination device in the transfer table C4 from the boundary device A before the failure detection to the protection route I, and the protection route I to the boundary device B. To send the packet.
The border device B transmits the packet from the border device B to the device G when the packet received from the relay device C has the backup route identifier.

However, when the present invention is applied, there is a problem that packet duplication occurs when the boundary device receives multicast traffic.
An operation in which multicast packets to be transmitted are duplicated when the present invention is applied will be described with reference to FIGS. 7 and 8. FIG. 7 is a diagram showing an example of an operation of performing multicast using different networks according to the embodiment of the present invention. FIG. 8 is a diagram showing an example of a problem in which multicast packets are transmitted in duplicate when a boundary device fails in an embodiment of the present invention.
For example, as shown in FIG. 7, (1) border device A and border device B having a redundant configuration, (2) border device E and border device F having a redundant configuration, (3) relay device C, (4) relay Consider a network including a device D and (5) a device G and a device H belonging to a network different from the network configured by the devices A to F.

The boundary device E transmits the multicast to the device H connected only to the boundary device A. Therefore, when the boundary device E receives this multicast at the port E3, all boundary devices that accommodate the destination opposite device (device E) Send a packet to the device.

When the device G connected to the boundary device A and the boundary device B receives the multicast from both the boundary device A and the boundary device B, the same packet is duplicated in the device G. Therefore, the device G is the boundary device. It is general that either A or the boundary device B takes the operation of discarding the multicast.

Next, as shown in FIG. 8, (1) a boundary device A and a boundary device B to which the present invention is applied in a redundant configuration, (2) a boundary device E and a boundary device F in a redundant configuration, and (3) relay The device C, (4) the relay device D, (5) the device G belonging to a network different from the network configured by the devices A to F, and (6) the backup route H used when the relay device C detects a failure, Consider a network that has a faulty boundary device A.

When the boundary device A fails, the multicast traffic addressed to the boundary device A and the multicast traffic addressed to the boundary device B via the backup route H reach the boundary device B.
When the present invention is applied to the network of FIG. 8, the boundary device B transmits to the device G all the packets to which the backup route identifier is added and the packets destined to the boundary device B. Therefore, the boundary device B transmits the same multicast packet from the boundary device B to the device G.

Therefore, in order to prevent the duplication of the multicast, in the present invention, when the backup route identifier is added to the multicast packet, the multicast packet is discarded and an operation of preventing the duplication of the packet is added.

The operation of preventing duplication of multicast will be described with reference to FIG. FIG. 9 is a diagram showing an example of an operation of preventing duplicate transmission of a multicast packet when a boundary device fails in the embodiment of the present invention.
As shown in FIG. 9, (1) a boundary device A and a boundary device B having a redundant configuration, (2) a boundary device E and a boundary device F having a redundant configuration, (3) a relay device C, and (4) a relay device D. , (5) a device G belonging to a network different from the network configured by the devices A to F, and (6) a backup route H used when the relay device C detects a failure, and the boundary device A Consider a network in which is broken.

When the boundary device A fails, the boundary device B receives the multicast packet in duplicate as described with reference to FIGS. 7 and 8.
(1) In the received packet, the boundary device B has the backup route identifier based on the presence/absence of the backup route identifier used in the network configured by the devices A to F, and (2) the destination information of the packet. And the packet whose destination information is multicast is determined and the packet is discarded.
By discarding the packets described above, it is possible to prevent duplication of packets while shortening the communication interruption time when the boundary device fails.

FIG. 10 is a diagram showing an example of a network configuration for explaining an embodiment of the present invention. In the example shown in FIG. 10, the network to which the relay devices C and D belong (hereinafter sometimes referred to as this network), the adjacent network to which the devices G and H belong, and the boundary device A that belongs to both networks. List B as an element.

In the example shown in FIG. 10, the boundary device A has a network connection port 10a, a connection port 10b for the device G, and a connection port 10c for the device H. The boundary device B has a network connection port 20a, a connection port 20b for the device G, and a connection port 20c for the device H.

The relay device C has a port 30a and a port 30b. The relay device D has a port 40a and a port 40b. The device G has a port 70a and a port 70b. The device H has a port 80a and a port 80b.

The port 10a is communicatively connected to the port 30a. The port 10b is communicatively connected to the port 70a. The port 10c is communicatively connected to the port 80a.
The port 20a is communicatively connected to the port 40a. The port 20b is communicatively connected to the port 70b. The port 20c is communicatively connected to the port 80b.
The port 30b is communicatively connected to the port 40b.
The present network shows a network connection port of each boundary device, and a portion including a relay device C and a relay device D.
The adjacent network indicates a connection port for the device G of each boundary device, a connection port for the device H, and a portion configured by the devices G and H.
In the following description, the device G and the device H have a device redundant configuration with two boundary devices A and B, and can receive a packet transmitted from any of the boundary devices in this device redundant configuration.

In the following description of the embodiments, the description of the relay device C and the relay device D belonging to the present network may be omitted, but the packet received from the network connection port is received via the network. Shows the packet that was made.
If the adjacent network is a packet network (for example, Ethernet), the present invention can be applied.
In the following description of the embodiments, two boundary devices have a device redundant configuration, but the present invention is applicable regardless of the number of boundary devices.

FIG. 11 is a diagram showing an example of an operation when a boundary device has a failure in a device redundant configuration in which the number of boundary devices exceeds two in an embodiment of the present invention.
In the example shown in FIG. 11, device redundancy is performed by N boundary devices including the first boundary device 10 (boundary device A), the second boundary device 20 (boundary device B), and the Nth boundary device 25 (boundary device C). A configuration is adopted, and corresponding to this configuration, N including the first relay device 30 (relay device C), the second relay device 40 (relay device D), and the Nth relay device 45 (relay device E) in this network. A relay device is provided.

When the boundary device (for example, the boundary device A in FIG. 11) fails, a standby route is set from the relay device that receives the packet addressed to the boundary device A regardless of the number of boundary devices, and the boundary device different from the failed boundary device is set. (For example, the boundary device C in FIG. 11) needs to transmit a packet (for example, a packet addressed to the device G) to the adjacent network.

When the present invention is applied to all the boundary devices having the device redundant configuration, the boundary device C can judge the packet via the backup route and transmit it to the adjacent network, so that the communication can be restored.

The operation shown in FIG. 11 can be applied to the present invention if a packet can be transmitted to another boundary device in a redundant configuration with the failed boundary device via a backup path when the boundary device fails. , It is possible to recover communication regardless of the number of boundary devices.

(First embodiment)
FIG. 12 is an example of the configuration of a functional unit for transmitting a packet that passes through a backup route to a failed boundary device from a device that has a redundant configuration with the failed boundary device when the boundary device fails in one embodiment of the present invention. FIG.
Here, using FIG. 12, a plurality of devices arranged at the boundary of the network are paired with the failed boundary device and the device redundancy when the boundary device that performs the device redundant operation among the plurality of devices fails. An operation example will be described in which the boundary device restores communication by transmitting to the adjacent network a packet that passes through the backup route with the failed boundary device set as the destination.

In the example shown in FIG. 12, the boundary device B has the network connection port 20a (see FIG. 10), the connection port 20b for the device G (see FIG. 10), the connection port 20c for the device H (see FIG. 10), and the transmission. It has a destination network determination unit 20d, a destination information table 20e, a packet format conversion unit 20f, and an adjacent network transmission function unit 20g.
The destination information table 20e records (1) own device information for determining a packet addressed to the own device, and (2) a backup route identifier of a backup route addressed to the boundary device A.

Specifically, the destination information table 20e forms (1) information for determining that the received packet is addressed to the boundary device B (to its own device), and (2) a pair of the boundary device B and device redundancy. It records the auxiliary route identifier that is given to the packet transmitted via the own device by the auxiliary route with the boundary device A as the destination.

Hereinafter, an operation example will be described.
The boundary device B transmits a packet addressed to the boundary device A (unicast addressed to the terminal device A, or terminal device) transmitted from this network via the backup route addressed to the boundary device A in FIG. 12 when the boundary device A fails. Multicast addressed to A) is received.

For the packet received from the network connection port 20a, the destination network determination unit 20d of the boundary device B determines whether to transmit the packet from the own device to the adjacent network based on the information in the destination information table 20e. It is determined whether the destination is an adjacent network.

The destination network determination unit 20d determines the destination network based on the information recorded in the destination information table 20e. Hereinafter, this determination will be described.
FIG. 13 is a diagram showing an example of a determination flow of the destination network determination unit in the embodiment of the present invention.
When the destination network determination unit 20d receives the packet (S1), if the received packet is addressed to itself (Yes in S2), the destination network determination unit 20d of the border device B determines that the received packet is an adjacent network. It is determined that the packet is a packet to be transmitted to the packet format conversion unit 20f (S3).

On the other hand, when the received packet is not addressed to the own device (No in S2), and the backup route identifier is added to the received packet (Yes in S4), the destination network determination unit 20d causes the destination network determination unit 20d to set the adjacent network to the adjacent network. The packet is determined to be a packet to be transmitted, and the packet is output to the packet format conversion unit 20f in order to transmit the packet to the adjacent network (S3).

If the received packet is not addressed to the device itself (No in S2) and the backup route identifier is not added to the received packet (No in S4), the destination network determination unit 20d determines that the received packet is It is determined that the packet is not a packet to be transmitted to the adjacent network but a packet to be returned to this network, and the packet is transmitted according to the destination information of the packet (S5).

After S3, the packet format conversion unit 20f included in the boundary device B deletes the destination information of the packet output by the destination network determination unit 20d.
After deleting the destination information of the packet, the packet format conversion unit 20f selects which adjacent network the packet is to be transmitted to.

In the operation example illustrated in FIG. 12, the packet format conversion unit 20f of the boundary device B selects the adjacent network to which the devices G and H belong as the destination of the packet.
After the determination of the destination network of the packet is completed, the packet format conversion unit 20f of the boundary device B converts the format of the packet into a format suitable for the adjacent network to which the devices G and H belong, and transmits the adjacent network. Output to the functional unit 20g.

The adjacent network transmission function unit 20g of the boundary device B determines the destination port of the packet output by the packet format conversion unit 20f, and transmits the packet to the devices G and H via the determined port.
As described above, by applying the first embodiment of the present invention, it is possible to recover communication without waiting for the communication interruption during the route recalculation time which occurs due to the use of the routing protocol.

(Second embodiment)
FIG. 14 is a function for transmitting a packet, which passes through a backup route to a device having a redundant configuration with the fault boundary device, from the device having the redundant border device when the boundary device fails in one embodiment of the present invention. It is a figure which shows an example of a structure of a part.
With reference to FIG. 14, when a plurality of devices are arranged at the boundary of the network and a boundary device that performs a device redundant operation between the plurality of devices fails, a boundary device that is a pair of the failed boundary device and the device redundancy is A description will be given of an operation example in which communication is restored by transmitting a packet passing through a backup route having the boundary device set as a destination to an adjacent network.

The boundary device B shown in FIG. 14 has the same configuration as the boundary device B shown in FIG. Further, the destination information table 20e records (1) own device information for determining a packet addressed to the own device and (2) a backup route identifier of a backup route addressed to the boundary device B.

Specifically, the destination information table 20e includes (1) information for determining that the received packet is addressed to the boundary device B (addressed to its own device), and (2) addressed to the boundary device B, and the backup route. The backup route identifier given to the packet transmitted to the own device is recorded.

Hereinafter, an operation example will be described.
When the boundary device A fails, the boundary device B transmits a packet addressed to the boundary device A (unicast to the terminal device A or to the terminal device), which is transmitted from this network through the backup route to the boundary device B in FIG. Multicast addressed to A) is received.

The destination network determination unit 20d of the boundary device B determines whether or not the packet received from the network connection port 20a is transmitted to the adjacent network based on the information in the destination information table 20e.

The destination network determination unit 20d determines the destination network based on the information recorded in the destination information table 20e. This determination is similar to that of the first embodiment, except that the backup route identifier is the backup route identifier of the backup route addressed to the boundary device B.
The transmission of the packet output to the packet format conversion unit 20f is equivalent to the operation example described in the first embodiment.

As described above, by applying the second embodiment of the present invention, the communication is performed without waiting for the communication interruption during the route recalculation time which is caused by using the routing protocol, as in the first embodiment. Can be recovered.

(Third Embodiment)
FIG. 15 is a diagram showing an example of a configuration of a functional unit for preventing duplicate transmission of a multicast packet when a boundary device fails in the embodiment of the present invention.
In the operation example described in the first and second embodiments, an operation example of preventing duplicate transmission of packets when a multicast is received will be described with reference to FIG.

In the example shown in FIG. 15, the boundary device B has the network connection port 20a, the connection port 20b for the device G, the connection port 20c for the device H, and the destination network determination unit 20d as shown in FIGS. , A destination information table 20e, a packet format conversion unit 20f, an adjacent network transmission function unit 20g, and a duplicate packet discard unit 20h.

Further, the boundary device B (1) own device information for judging a packet addressed to the own device in the destination information table 20e, and (2) a backup route of the backup route to the boundary device A or to the boundary device B. Record the identifier and.

Hereinafter, an operation example will be described. FIG. 16 is a diagram showing an example of the discard flow of the duplicate packet discard unit in the embodiment of the present invention.
In this operation example, the destination network determination unit 20d of the boundary device B outputs the packet determined to be transmitted to the adjacent network in the operation examples of the first and second embodiments to the duplicate packet discard unit 20h (S11). ).

The duplicated packet discard unit 20h determines whether the packet output by the destination network determination unit 20d is provided with a backup route identifier based on the information in the destination information table 20e held by the terminal device B. ..
Further, the duplicate packet discard unit 20h determines from the destination information of the received packet whether the packet is treated as a multicast in this network.

The duplicate packet discard unit 20h determines the discard as follows based on the above determination.
If the received packet has a backup path identifier (Yes in S12) and this packet is treated as a multicast in this network (Yes in S13), the duplicate packet discard unit 20h discards the packet. (S14).

If the received packet has a backup route identifier and is treated as unicast rather than as multicast in this network (No in S13), the duplicate packet discard unit 20h will handle the packet. It is output to the packet format converter 20f (S15).

If the backup path identifier is not added to the received packet (No in S12), the duplicate packet discard unit 20h outputs the packet to the packet format conversion unit 20f (S15).
The transmission of the packet output to the packet format conversion unit 20f is equivalent to the operation example described in the first embodiment.

As described above, by applying the third embodiment of the present invention, it is possible to prevent the duplicate transmission of the multicast packet that occurs in the first and second embodiments.

It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified at the stage of implementation without departing from the spirit of the invention. Further, the respective embodiments may be appropriately combined and implemented, in which case the combined effects can be obtained. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by a combination selected from a plurality of disclosed constituent features. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, if the problem can be solved and the effect can be obtained, the structure in which the constituent elements are deleted can be extracted as the invention.

In addition, the method described in each embodiment is, for example, a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM,) as a program (software means) that can be executed by a computer (computer). It can also be stored in a recording medium such as a DVD, MO, etc.), a semiconductor memory (ROM, RAM, flash memory, etc.), or transmitted by a communication medium for distribution. It should be noted that the programs stored on the medium side also include setting programs for configuring software means (including not only execution programs but also tables and data structures) to be executed by the computer in the computer. A computer that realizes this device reads a program recorded in a recording medium, and if necessary, constructs software means by a setting program, and the operation is controlled by this software means to execute the processing described above. The recording medium referred to in this specification is not limited to distribution, but includes a storage medium such as a magnetic disk or a semiconductor memory provided inside a computer or in a device connected via a network.

10... 1st boundary device, 20... 2nd boundary device, 20d... Destination network judgment part, 20e... Destination information table, 20f... Packet format conversion part, 20g... Adjacent network transmission function part, 20h... Duplicate packet discard part, 30... 1st relay apparatus, 40... 2nd relay apparatus, 50... 3rd boundary device, 60... 4th boundary device.

Claims (5)

For redundancy against a network failure, a normal path used for normal communication and a backup path used for communication when the normal path fails are preset, and a communication path used when the normal path fails Boundary devices that perform a device redundant operation by arranging a plurality of units at the boundary between the main network that switches the pair to the backup path to restore communication and the adjacent network that communicates with each other by connecting to the main network A communication device used as
(1) When receiving a packet from the present network, own device information used for determining whether or not the destination of the received packet is the own device; and (2) forming a pair of the own device and the device redundancy. A storage unit that stores a destination information table that records, as a destination, another border device, and a backup route identifier that is destination information given to a packet that passes through the backup device via the backup device,
When a packet is received from the present network, the received packet is a packet to be transmitted from the own device to the adjacent network based on the own device information and the backup route identifier recorded in the destination information table. A destination network determining unit that determines whether or not
The destination network determination unit deletes the destination information added to the packet determined to be the packet to be transmitted to the adjacent network, and after this deletion, the received packet is transmitted to a plurality of devices to which the own device is connected. A packet format conversion unit that selects which of the adjacent networks is to be transmitted, and converts the format of the received packet into a format suitable for the selected adjacent network,
A network connection port used for transmission of the packet whose format has been converted by the packet format conversion unit, and an adjacent network transmission function unit that transmits the converted packet to the determined network connection port. .. For the packet determined by the destination network determination unit to be a packet to be transmitted to the adjacent network, depending on the information in the destination information table and whether the received packet is treated as a multicast in the adjacent network. The communication device according to claim 1 , further comprising: a duplicate packet discard unit that determines whether to transmit or discard the packet to the adjacent network. For redundancy against a network failure, a normal path used for normal communication and a backup path used for communication when the normal path fails are preset, and a communication path used when the normal path fails Boundary devices that perform a device redundant operation by arranging a plurality of units at the boundary between the main network that switches the pair to the backup path to restore communication and the adjacent network that communicates with each other by connecting to the main network A method applied to a communication device used as
The communication device is
(1) When receiving a packet from the present network, own device information used for determining whether or not the destination of the received packet is the own device; and (2) forming a pair of the own device and the device redundancy. A storage unit that stores a destination information table that records another border device as a destination and a backup route identifier that is destination information given to a packet passing through the device by the backup route,
When a packet is received from the present network, the received packet is a packet to be transmitted from the own device to the adjacent network based on the own device information and the backup route identifier recorded in the destination information table. Or not,
The destination information added to the packet determined to be the packet to be transmitted to the adjacent network is deleted, and after this deletion, which of the adjacent networks the own device is connected to the received packet is Selecting whether to send to the network, converting the format of the received packet into a packet format compatible with the selected adjacent network,
A communication method, wherein a network connection port used for transmission is determined for a packet whose format has been converted, and the converted packet is transmitted to the determined network connection port. Regarding a packet determined to be a packet to be transmitted to the adjacent network, the packet is determined according to the information in the destination information table and the information indicating whether the received packet is treated as multicast in the adjacent network. The communication method according to claim 3 , wherein it is determined whether to transmit to the adjacent network or to discard. A program used in a computer operating as a part of the communication device according to claim 1 ,
The computer,
A communication processing program for causing the storage unit, the destination network determination unit, the packet format conversion unit, and the adjacent network transmission function unit to function.