Packet control system

Abstract

To provide a packet control system capable of continuously forwarding packets even during a line exchange failure.SOLUTION: When a first gateway device 20 detects a failure of a line exchange 30, the first gateway device 20 transmits IP packets transmitted from a first terminal 10 to the line exchange 30 of a second gateway device 40. When the second gateway device 40 detects a failure of the line exchange 30, the second gateway device 40 transmits IP packets transmitted from a second terminal 50 to the line exchange 30 of the first gateway device 20.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a packet control system.

Background Art

[0002] Conventionally, with the rapid development of the Internet, IP telephones have become widespread. In a VoIP (Voice over IP) system using an IP telephone, packets transmitted from a first terminal are transmitted to a second terminal different from the first terminal via a circuit switch (subscriber accommodation facility). Similarly, packets transmitted from the second terminal are transmitted to the first terminal via the circuit switch. Session control is performed between the first terminal and the circuit switch and between the circuit switch and the second terminal via a gateway device called an SBC (Session Border Controller).

[0003] For example, a technique for an IP telephone system that transfers data between a first terminal and a second terminal is disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in such a system, when a failure occurs in the circuit switch, it is impossible to transmit and receive packets including voice and media information between the first terminal and the second terminal. In this case, packet transmission and reception cannot be performed until the circuit switch is restored, and there has been a problem that services such as IP telephones using packets are stopped.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a packet control system capable of continuously transferring packets even when a circuit switch fails.

Means for Solving the Problems

[0007] One aspect of the packet control system of the present invention is a packet control system including a first gateway device that transmits an IP packet transmitted from a first terminal to a circuit switch, and a second gateway device that transmits the IP packet from the first terminal transmitted via the circuit switch to a second terminal. The first gateway device transmits the IP packet transmitted from the first terminal to the circuit switch when the failure of the circuit switch is not detected, and when the failure of the circuit switch is detected, the IP packet transmitted from the first terminal is transmitted to the second gateway device or the second gateway device and the circuit switch. The second gateway device transmits the IP packet transmitted from the second terminal to the circuit switch when the failure of the circuit switch is not detected, and when the failure of the circuit switch is detected, the IP packet transmitted from the second terminal is transmitted to the first gateway device or the first gateway device and the circuit switch.

[0008] With this configuration, even when a circuit switch fails, it is possible to transmit an IP packet by bypassing the circuit switch that has failed via the first gateway device and the second gateway device, so that the IP packet can be continuously transferred and the service can be continued.

[0009] In one aspect of the packet control system of the present invention, when the first gateway device detects a failure of the circuit switch and is unable to receive the IP packets transmitted from the circuit switch at a predetermined interval, it detects that a failure has occurred in the circuit switch and transmits the IP packets transmitted from the first terminal to the second gateway device, or to the second gateway device and the circuit switch. When the second gateway device is unable to receive the IP packets transmitted from the circuit switch at a predetermined interval, it detects that a failure has occurred in the circuit switch and transmits the IP packets transmitted from the second terminal to the first gateway device, or to the first gateway device and the circuit switch. This is preferable.

[0010] In one aspect of the packet control system of the present invention, when the first gateway device can receive the IP packets again from the circuit switch at a predetermined timing, it detects that the failure of the circuit switch has been recovered and transmits the IP packets transmitted from the first terminal to the second gateway device, or to both the second gateway device and the circuit switch. When the second gateway device can receive the IP packets from the circuit switch at a predetermined timing, it detects that the failure of the circuit switch has been recovered and transmits the IP packets transmitted from the second terminal to the first gateway device, or to both the first gateway device and the circuit switch. This is preferable.

[0011] In one aspect of the packet control system of the present invention, it is preferable that the first gateway device and the second gateway device discard the IP packets transmitted from the circuit switch when a failure of the circuit switch occurs.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a packet control system capable of continuously transferring packets even when a circuit switch fails.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0015] (This Embodiment) Hereinafter, an embodiment in which the gateway device of the present invention is applied to a packet control system that performs transmission and reception of IP packets between a first terminal and a second terminal on an IP network will be described. In this network, for example, a protocol for directly performing two-way real-time communication of multimedia data end-to-end is adopted. In this embodiment, for example, SIP (Session Initiation Protocol) is adopted as the protocol. Services realized by SIP include, for example, IP telephony, video conferencing, instant messaging, and the like.

[0016] FIG. 1 is a diagram showing an example of a packet control system including a gateway device according to this embodiment. The packet control system 100 includes a first terminal 10, a first gateway device 20, a circuit switch 30, a second gateway device 40, and a second terminal 50.

[0017] The first terminal 10 and the second terminal 50 may be any terminals having a communication function. For example, the first terminal 10 and the second terminal 50 are mobile phones such as smartphones, tablet terminals, and PCs (Personal Computers). In FIG. 1, the packet control system 100 includes one first terminal 10 and one second terminal 50, but this is not the limit, and a plurality of them may be included.

[0018] The first terminal 10 is connected to the circuit switch 30 via the first gateway device 20. The first terminal 10 is, for example, an originating terminal of an IP phone. The first terminal 10 performs transmission and reception of IP packets with the second terminal 50 at the time of originating a call. The first terminal 10 is equipped with a protocol stack corresponding to SIP and RTP (Real-time Transport Protocol), and has a function of sending an originating request (INVITE) to the second terminal 50 based on SIP. Note that the first terminal 10 may also have a function of sending a successful response (200 OK) to an originating request (INVITE) from the second terminal 50.

[0019] The second terminal 50 is connected to the circuit switch 30 via the second gateway device 40. The second terminal 50 is, for example, an incoming call terminal of an IP phone. When receiving an incoming call, the second terminal 50 transmits and receives IP packets to and from the first terminal 10 via the first gateway device 20, the circuit switch 30, and the second gateway device 40. The second terminal 50 is equipped with a protocol stack corresponding to SIP and RTP, and has a function of sending a successful response (200 OK) to an outgoing call request (INVITE) from the first terminal 10 to the second gateway device 40, the circuit switch 30, and the first gateway device 20 via SIP. Note that the second terminal 50 may have a function of sending an outgoing call request (INVITE) to the first terminal 10.

[0020] The first gateway device 20 is connected between the first terminal 10 and the circuit switch 30. When transmitting and receiving IP packets between the first terminal 10 and the second terminal 50 via the second gateway device 40, the circuit switch 30, and the first gateway device 20, the first gateway device 20 conceals the configuration within the network domain on the first terminal 10 side as a gateway. The first gateway device 20 transmits the IP packet transmitted from the first terminal 10 to the second terminal 50 via the circuit switch 30 and the second gateway device 40.

[0021] The second gateway device 40 is connected between the second terminal 50 and the circuit switch 30. When transmitting and receiving IP packets between the first terminal 10 and the second terminal 50 via the first gateway device 20, the circuit switch 30, and the second gateway device 40, the second gateway device 40 conceals the configuration within the network domain on the second terminal 50 side as a gateway. The second gateway device 40 transmits the IP packet transmitted from the first terminal 10 via the first gateway device 20 and the circuit switch 30 to the second terminal 50. As the first gateway device 20 and the second gateway device 40, for example, an SBC (Session Border Controller) is adopted.

[0022] Note that the circuit switch 30 transmits IP packets to the first gateway device 20 and the second gateway device 40 at predetermined intervals. The second gateway device 40 can detect whether a failure has occurred in the circuit switch 30 based on the IP packets transmitted from the circuit switch 30. That is, when the second gateway device 40 cannot receive the IP packets transmitted from the circuit switch 30 at predetermined intervals, it can detect that a failure has occurred in the circuit switch 30. Similarly, when the first gateway device 20 cannot receive the IP packets transmitted from the circuit switch 30 at predetermined intervals, it can detect that a failure has occurred in the circuit switch 30. Note that the method for detecting that a failure has occurred in the circuit switch 30 is not limited to this, and known techniques can be adopted.

[0023] FIG. 2 is a diagram for explaining an overview of the first gateway device 20 and the second gateway device 40 executed in the packet control system 100 that performs transmission and reception of IP packets before a failure occurs in the circuit switch 30.

[0024] In the example shown in FIG. 2, the first terminal 10 performs transmission and reception of IP packets with the circuit switch 30 via the first gateway device 20. That is, the first gateway device 20 relays the communication of the first terminal 10. The circuit switch 30 performs transmission and reception of IP packets with the second terminal 50 via the second gateway device 40. That is, the second gateway device 40 relays the communication of the second terminal 50. The packet control system 100 establishes a communication connection between the first terminal 10 and the second terminal 50 in response to a request from the first terminal 10 or the second terminal 50.

[0025] Specifically, the first terminal 10 transmits an IP packet including call control information to the second terminal 50. The first gateway device 20, the circuit switch 30, the second gateway device 40, and the second terminal 50 can acquire the call control information from the IP packet. In this case, the call control information is used in protocols such as SIP and H.323, but is not particularly limited.

[0026] In SIP, the SIP message, which is call control information, is in text format and is divided into a start line (status line), a header section, and a body section. In the body section, call control information such as the source address of the first terminal 10, port information, and compression format is described in the description syntax of SDP (Session Description Protocol).

[0027] As shown in FIG. 2, the first terminal 10 transmits an invitation request (INVITE) to the first gateway device 20 (S11). The invitation request (INVITE) of the first terminal 10 describes the destination address of the first gateway device 20 and the like.

[0028] When the first gateway device 20 cannot receive the IP packets transmitted from the circuit switch 30 at a predetermined interval, it detects that a failure has occurred in the circuit switch 30. Note that the detection of whether a failure has occurred in the circuit switch 30 may be performed by other known techniques.

[0029] Before a failure occurs in the circuit switch 30, the first gateway device 20 transmits the invitation request (INVITE) received from the first terminal 10 to the circuit switch 30 (S12). Before a failure occurs in the circuit switch 30, the first gateway device 20 may transmit the invitation request (INVITE) received from the first terminal 10 to the circuit switch 30 and the second gateway device 40. The invitation request (INVITE) transmitted by the first gateway device 20 describes information such as the source address of the first gateway device 20 (encapsulation).

[0030] The circuit switch 30 transmits the invitation request (INVITE) received from the first gateway device 20 to the second gateway device 40 (S13). The invitation request (INVITE) transmitted by the circuit switch 30 describes the source address of the first gateway device 20 and the like (encapsulation).

[0031] Before the failure of the circuit switch 30, the second gateway device 40 transmits the outgoing call request (INVITE) received from the circuit switch 30 to the second terminal 50 (S14). In this case, the second gateway device 40 stores in advance the first gateway device 20, which is the source of the outgoing call request (INVITE), as the destination at the time of failure, based on the source address included in the outgoing call request (INVITE). Before the failure of the switch, the second gateway device 40 may discard the outgoing call request (INVITE) directly transmitted from the first gateway device 20.

[0032] The second terminal 50 transmits a successful response (200 OK) to the outgoing call request (INVITE) from the first terminal 10 to the second gateway device 40 (S21). The successful response (200 OK) from the second terminal 50 describes the destination address of the first terminal 10 and the like.

[0033] Before the failure of the circuit switch 30, the second gateway device 40 transmits the successful response (200 OK) received from the second terminal 50 to the circuit switch 30 (S22). Before the failure of the circuit switch 30, the second gateway device 40 may transmit the successful response (200 OK) received from the second terminal 50 to the circuit switch 30 and the first gateway device 20. The successful response (200 OK) transmitted by the second gateway device 40 describes information such as the source address of the second gateway device 40 (encapsulation).

[0034] The circuit switch 30 transmits the successful response (200 OK) received from the second gateway device 40 to the first gateway device 20 (S23). The successful response (200 OK) transmitted by the circuit switch 30 describes the source address of the second gateway device 40 and the like.

[0035] When the second gateway device 40 cannot receive the IP packets transmitted from the circuit switch 30 at a predetermined interval, it detects that a failure has occurred in the circuit switch 30.

[0036] Before the failure of the circuit switch 30, the first gateway device 20 transmits the success response (200 OK) received from the circuit switch 30 to the first terminal 10 (S24). In this case, the first gateway device 20 stores the second gateway device 40, which is the source of the IP packet, as the transmission destination at the time of failure, based on the source address included in the success response (200 OK). Before the failure of the circuit switch 30, the first gateway device 20 discards the success response (200 OK) directly transmitted from the second gateway device 40.

[0037] Figure 3 is a diagram showing the operation when the circuit switch 30 detects that it has exited the failure state and recovered, for the information (recover) of the transmission parameters of the encapsulated information. As shown in Figure 3, the INVITE (call request) of the first gateway device 20 is divided into a start line 61, a header section 62, and a body section 63. In the header section 62, as the information 64 of the transmission destination at the time of failure, the source address and port information of the first gateway device 20, and the information (recover) of the transmission parameters "X-ALTERDST: addr=192.168.0.188;port=8000;recover=true" are described (encapsulated). The information (recover) of the transmission parameters is information indicating the transmission method. When the information (recover) of the transmission parameters is "true", the first gateway device 20 transmits the IP packet to the second gateway device 40 via the circuit switch 30 when the first gateway device 20 and the second gateway device 40 detect that the circuit switch 30 has exited the failure state and recovered. When the information (recover) of the transmission parameters is "false", the first gateway device 20 and the second gateway device 40 transmit the IP packet between them even when the first gateway device 20 and the second gateway device 40 detect that the circuit switch 30 has exited the failure state and recovered.

[0038] FIG. 4 is a diagram showing the operation when the circuit switch 30 detects that it has recovered from a failure state. As shown in FIG. 4, the successful response (200 OK) of the second gateway device 40 is divided into a start line 71, a header section 72, and a body section 73. In the header section 72, as the information 74 of the destination at the time of failure, the source address and port information of the second gateway device 40 and the information of the transmission parameter (recover) “X-ALTERDST: addr = 192.168.0.189; port = 8000; recover = true” are described (encapsulated). The information of the transmission parameter (recover) is information indicating the transmission method. When the information of the transmission parameter (recover) is “true”, when the first gateway device 20 and the second gateway device 40 detect that the circuit switch 30 has recovered from a failure state, the IP packet is transmitted to the circuit switch 30 and the first gateway device 20 via the circuit switch 30. When the information of the transmission parameter (recover) is “false”, even when the first gateway device 20 and 40 detect that the circuit switch 30 has recovered from a failure state, the IP packet is transmitted between the first gateway device 20 and the second gateway device 40.

[0039] FIG. 5 is a diagram for explaining an overview of the first gateway device 20 and the second gateway device 40 that perform transmission and reception of IP packets in the packet control system 100 when a failure occurs in the circuit switch 30.

[0040] When the first gateway device 20 cannot receive the IP packet transmitted from the circuit switch 30 at a predetermined interval, it detects that a failure has occurred in the circuit switch 30. The first gateway device 20 and the second gateway device 40 perform the process of whether a failure has occurred in the circuit switch 30 at regular intervals. Note that the first gateway device 20 and the second gateway device 40 may detect whether a failure has occurred in the circuit switch 30 based on information received from other devices (not shown).

[0041] The first terminal 10 transmits an invitation request (INVITE) to the first gateway device 20 (S31). The invitation request (INVITE) of the first terminal 10 describes the destination address of the second terminal 50 and the like.

[0042] When a failure occurs in the circuit switch 30, the first gateway device 20 transmits the invitation request (INVITE) received from the first terminal 10 to the circuit switch 30 and the second gateway device 40 (S32, S33). When a failure occurs in the circuit switch 30, the first gateway device 20 may transmit the invitation request (INVITE) received from the first terminal 10 only to the second gateway device 40.

[0043] The destination of the second gateway device 40 is transmitted based on the information stored as the destination at the time of failure before the failure occurs. That is, it is transmitted based on the information of the source address and port of the second gateway device 40 shown in FIG. 3, which is described (encapsulated) as the information 64 of the destination at the time of failure, "X-ALTERDST: addr=192.168.0.189;port=8000;recover=true".

[0044] When a failure occurs in the circuit switch 30, the second gateway device 40 transmits the invitation request (INVITE) received from the first gateway device 20 to the second terminal 50 (S34). Note that when a failure occurs, the second gateway device 40 may discard the invitation request (INVITE) transmitted from the circuit switch 30.

[0045] The second terminal 50 transmits a successful response (200 OK) to the invitation request (INVITE) of the first terminal 10 to the second gateway device 40 (S41). The successful response (200 OK) of the second terminal 50 describes the destination address of the second gateway device 40 and the like.

[0046] When a failure occurs in the circuit switch 30, the second gateway device 40 transmits the success response (200 OK) received from the second terminal 50 to the circuit switch 30 and the first gateway device 20 (S42, S43). When a failure occurs in the circuit switch 30, the second gateway device 40 may transmit the success response (200 OK) received from the second terminal 50 only to the first gateway device 20. The success response (200 OK) transmitted by the second gateway device 40 describes (encapsulates) information such as the source address of the second gateway device 40.

[0047] The destination of the first gateway device 20 is transmitted based on the information stored as the destination at the time of failure before the failure occurs. That is, it is transmitted based on the source address and port information “X-ALTERDST: addr = 192.168.0.189; port = 8000; recover = true” of the first gateway device 20 shown in FIG. 4, which is described (encapsulated) as the information 74 of the destination at the time of failure.

[0048] When a failure occurs in the circuit switch 30, the first gateway device 20 transmits the success response (200 OK) received from the second gateway device 40 to the first terminal 10 (S44). Note that when a failure occurs, the first gateway device 20 may discard the success response (200 OK) transmitted from the circuit switch 30.

[0049] FIG. 6 is a diagram for explaining an overview of the first gateway device 20 and the second gateway device 40 executed in the packet control system 100 that performs transmission and reception of IP packets when the circuit switch 30 is restored.

[0050] When the first gateway device 20 can receive IP packets transmitted from the circuit switch 30 at a predetermined interval, it detects that the failure that occurred in the circuit switch 30 has been recovered. The first gateway device 20 and the second gateway device 40 perform the process of determining whether or not the failure that occurred in the circuit switch 30 has been recovered at regular intervals. Note that the first gateway device 20 and the second gateway device 40 may detect whether or not the failure that occurred in the circuit switch 30 has been recovered based on information received from other devices (not shown).

[0051] The first terminal 10 transmits an invitation request (INVITE) to the first gateway device 20 (S51). The invitation request (INVITE) from the first terminal 10 describes the destination address of the first gateway device 20 and the like.

[0052] When the failure of the circuit switch 30 is recovered, the first gateway device 20 transmits the invitation request (INVITE) received from the first terminal 10 to the circuit switch 30 (S52).

[0053] When the first gateway device 20 can receive IP packets transmitted from the circuit switch 30 at a predetermined interval, it detects that the failure that occurred in the circuit switch 30 has been recovered.

[0054] The circuit switch 30 transmits the invitation request (INVITE) received from the first gateway device 20 to the second gateway device 40 (S53). The invitation request (INVITE) transmitted by the circuit switch 30 describes (encapsulates) the source address of the first gateway device 20 and the like.

[0055] After the failure of the circuit switch 30 is recovered, the second gateway device 40 transmits the outgoing call request (INVITE) received from the circuit switch 30 to the second terminal 50 (S54). In this case, the second gateway device 40 stores the first gateway device 20, which is the source of the outgoing call request (INVITE), as the destination at the time of failure, based on the source address included in the outgoing call request (INVITE). Note that after the failure of the circuit switch 30 is recovered, the second gateway device 40 discards the outgoing call request (INVITE) directly transmitted from the first gateway device 20.

[0056] The second terminal 50 transmits a successful response (200 OK) to the outgoing call request (INVITE) of the first terminal 10 to the second gateway device 40 (S61). The successful response (200 OK) of the second terminal 50 describes the destination address of the second gateway device 40 and so on.

[0057] When the failure of the circuit switch 30 is recovered, the second gateway device 40 transmits the successful response (200 OK) received from the second terminal 50 to the circuit switch 30 (S62). The successful response (200 OK) transmitted by the second gateway device 40 describes (encapsulates) information such as the source address of the second gateway device 40.

[0058] The circuit switch 30 transmits the successful response (200 OK) received from the second gateway device 40 to the first gateway device 20 (S63). The successful response (200 OK) transmitted by the circuit switch 30 describes the source address of the second gateway device 40 and so on.

[0059] When the second gateway device 40 can receive IP packets transmitted from the circuit switch 30 at a predetermined interval, it detects that the failure that occurred in the circuit switch 30 has been recovered.

[0060] After the failure of the circuit switch 30 is recovered, the first gateway device 20 transmits the success response (200 OK) received from the circuit switch 30 to the first terminal 10 (S64). Note that when the failure of the circuit switch 30 is recovered, the first gateway device 20 discards the success response (200 OK) directly transmitted from the second gateway device 40.

[0061] FIG. 7 is a hardware configuration diagram of the first gateway device 20 in the present embodiment. Since the hardware configuration of the second gateway device 40 is the same as that of the first gateway device 20, the description thereof is omitted. As shown in FIG. 7, the first gateway device 20 is configured by connecting a control unit 81, an input device 82, a display device 83, a storage unit 84, and an interface (I / F) 85 to a bus 86. Further, the first gateway device 20 may include other hardware configurations not shown in FIG. 7.

[0062] The control unit 81 comprehensively controls the first gateway device 20 and the entire packet control system 100, and has a CPU (Central Processing Unit) that reads a program and executes IP packet control processing. The input device 82 inputs various data and signals, such as a keyboard, a joystick, a light pen, a mouse, a touch pad, a touch panel, a trackball, etc. The display device 83 outputs images and other information, such as various displays such as an LCD (Liquid Crystal Display), a printer, etc.

[0063] The storage unit 84 includes a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), etc. The storage unit 84 stores, in addition to the programs executed by the first gateway device 20, control programs for controlling and executing the respective functions of the first gateway device 20, information on the transmission destination in case of failure, and the like. The storage unit 84 provides a work area when the first gateway device 20 executes a program. Further, the storage unit 84 may store various databases (DBs) and other data, which will be described later.

[0064] The interface (I / F) 85 is a unit for connecting to the first terminal 10, the circuit switch 30, the second terminal 50, etc., such as a parallel interface such as Ethernet (registered trademark), a wireless LAN interface, a serial interface such as USB (Universal Serial Bus). The packet transfer process in the present embodiment is executed by the first gateway device 20 described above.

[0065] FIG. 8 is a hardware configuration diagram of the first terminal 10 in the present embodiment. Note that the hardware configuration of the second terminal 50 is the same as that of the first terminal 10, and thus the description thereof is omitted. As shown in FIG. 8, the first terminal 10 is configured such that a control unit 91, an input device 92, a display device 93, a storage unit 94, and an interface (I / F) 95 are connected to a bus 96. Further, the first terminal 10 may include other hardware configurations not shown in FIG. 8.

[0066] The control unit 91 comprehensively controls the entire first terminal 10 and has a CPU that reads a program and executes IP packet control processing. The input device 92 inputs various data and signals, such as a keyboard, a joystick, a light pen, a mouse, a touch pad, a touch panel, a trackball, etc. The display device 93 outputs images and other information, such as various displays such as an LCD, a printer, etc.

[0067] The storage unit 94 includes a RAM, a ROM, an HDD, etc. The storage unit 94 stores, in addition to the program for the first terminal 10 to execute IP packet control processing, a control program for controlling and executing each function of the first terminal 10, screen data, etc. The storage unit 94 provides a work area when the first terminal 10 executes a program. Further, the storage unit 94 may store various databases (DBs) and other data described later.

[0068] The interface (I / F) 95 is a unit for connecting to the first gateway device 20 and the second gateway device 40, such as a parallel interface like Ethernet, an interface for a wireless LAN, a serial interface like USB, etc.

[0069] In the above-described embodiment, when the first gateway device 20 does not detect a failure of the circuit switch 30, the first gateway device 20 transmits an outgoing call request (INVITE) transmitted from the first terminal 10 to the circuit switch 30. When the first gateway device 20 detects a failure of the circuit switch 30, the first gateway device 20 transmits an outgoing call request (INVITE) transmitted from the first terminal 10 to the second gateway device 40 and the circuit switch 30. Then, when the first gateway device 20 detects a failure of the circuit switch 30, the first gateway device 20 transmits the IP packet transmitted from the first terminal 10 to the second gateway device 40, or to the second gateway device 40 and the circuit switch 30.

[0070] When the second gateway device 40 does not detect a failure of the circuit switch 30, the second gateway device 40 transmits a success response (200 OK) transmitted from the second terminal 50 to the circuit switch 30. On the other hand, when the second gateway device 40 detects a failure of the circuit switch 30, the second gateway device 40 transmits a success response (200 OK) transmitted from the second terminal 50 to the first gateway device 20, or to the first gateway device 20 and the circuit switch 30.

[0071] With the above configuration, even when a failure occurs in the circuit switch 30, it is possible to transmit and receive a successful response (200 OK) and an invitation request (INVITE) by bypassing the circuit switch 30 that has failed via the first gateway device 20 and the second gateway device 40. Therefore, IP packets can be continuously transferred to continue the service.

[0072] In the above-described embodiment, the first gateway device 20 and the second gateway device 40 are each arranged on the first terminal 10 side and the second terminal 50 side, but this is not the only case, and a plurality of them may be arranged. In this case, when a failure occurs in the circuit switch 30, the plurality of gateway device groups arranged on the second terminal 50 side each transmit the successful response (200 OK) received from the second terminal 50 to the first gateway device 20 arranged on the first terminal 10 side. The first gateway device 20 transmits any one of the successful responses (200 OK) received from the gateway device groups arranged on the second terminal 50 side to the first terminal 10. The first gateway device 20 may transmit the successful response (200 OK) received from the gateway device closest to the first gateway device 20 among the gateway device groups arranged on the second terminal 50 side to the first terminal 10.

[0073] As described above, the present invention has been described in detail. However, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed aspects without departing from the spirit and scope of the present invention as defined by the claims. Therefore, the description in this specification is for the purpose of illustrative explanation and has no restrictive meaning for the present invention. The processing procedures of each aspect / embodiment described in this specification may be rearranged as long as there is no contradiction.

[0074] In the above-described embodiment, the packet control system 100 includes the first terminal 10, the first gateway device 20, the circuit switch 30, the second gateway device 40, and the second terminal 50, but this is not the limit. For example, in another embodiment, the packet control system 100 may be composed of the first terminal 10, the first gateway device 20, the circuit switch 30, and the second terminal 50 without including the second gateway device 40. In the packet control system 100 in another embodiment, the first gateway device 20, that is, one gateway device accommodates the first terminal 10 as the originating terminal and the second terminal 50 as the terminating terminal. In this case, the functions of both the first gateway device 20 and the second gateway device 40 in the above-described embodiment are implemented in the first gateway device 20.

Industrial Applicability

[0075] The present invention has an effect that packets can be continuously transferred even when a circuit switch fails, and can be suitably used for a packet control system or the like.

Explanation of Reference Numerals

[0076] 10 First terminal 20 First gateway device 30 Circuit switch 40 Second gateway device 50 Second terminal 100 Packet control system

Claims

1. A first gateway device that transmits an IP packet transmitted from a first terminal to a circuit switch and transmits, to the first terminal, an IP packet received from the circuit switch and having the first terminal as a destination, and a second gateway device that transmits an IP packet transmitted from a second terminal to the circuit switch and transmits, to the second terminal, an IP packet received from the circuit switch and having the second terminal as a destination, the packet control system comprising: wherein the first gateway device when not detecting a failure of the circuit switch encapsulates first failure-time destination information including the address of the first gateway device when transmitting an IP packet transmitted from the first terminal to the circuit switch, acquires and stores second failure-time destination information encapsulated in an IP packet received from the circuit switch and directed from the second terminal to the first terminal, when detecting a failure of the circuit switch, transmits an IP packet transmitted from the first terminal to the second gateway device or to the second gateway device and the circuit switch based on the second failure-time destination information; wherein the second gateway device when not detecting a failure of the circuit switch encapsulates the second failure-time destination information including the address of the second gateway device when transmitting an IP packet transmitted from the second terminal to the circuit switch, acquires and stores the first failure-time destination information encapsulated in an IP packet received from the circuit switch and directed from the first terminal to the second terminal, when detecting a failure of the circuit switch, transmits an IP packet transmitted from the second terminal to the first gateway device or to the first gateway device and the circuit switch based on the first failure-time destination information; A packet control system characterized by the above.

2. wherein the first gateway device when unable to receive an IP packet transmitted from the circuit switch at a predetermined interval, detects that a failure has occurred in the circuit switch and transmits an IP packet transmitted from the first terminal to the second gateway device or to the second gateway device and the circuit switch, wherein the second gateway device When it is unable to receive IP packets transmitted from the circuit switch at a predetermined interval, it detects that a failure has occurred in the circuit switch, and transmits the IP packets transmitted from the second terminal to the first gateway device or to the first gateway device and the circuit switch. The packet control system according to claim 1, characterized in that.

3. The first gateway device When it is able to receive IP packets transmitted from the circuit switch at a predetermined interval after detecting that a failure has occurred in the circuit switch, it detects that the failure of the circuit switch has been recovered, and transmits the IP packets transmitted from the first terminal to the second gateway device or to both the second gateway device and the circuit switch. The second gateway device When it is able to receive IP packets transmitted from the circuit switch at a predetermined interval after detecting that a failure has occurred in the circuit switch, it detects that the failure of the circuit switch has been recovered, and transmits the IP packets transmitted from the second terminal to the first gateway device or to both the first gateway device and the circuit switch. The packet control system according to claim 1 or claim 2, characterized in that.

4. When a failure occurs in the circuit switch, the first gateway device discards the IP packets transmitted from the circuit switch and directed from the second terminal to the first terminal. When a failure occurs in the circuit switch, the second gateway device discards the IP packets transmitted from the circuit switch and directed from the first terminal to the second terminal. The packet control system according to claim 2, characterized in that.

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