JP2002077261A - Virtual private line network connection control method, virtual private line network connection controller and virutal private line network connection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a virtual private line network connection control method, its controller and system for connecting VPN devices which even in a communication environment where an IP address is dynamically allocated such as internet connection by means of dial-up. SOLUTION: The instruction of connection to the Internet is given to the VPN device 20b of a stronghold-side from a VPN connection control part 12, installed in a VPN connection controller 10 via the VPN device 20a and a B2 channel 32a on a center-side and an ISDN network 75. The VPN device 20b receives the instruction and connects it to the connection device 60b of ISP, by using a B1 channel 31b and receives the allocation of the IP address from ISP. The IP address is notified to the VPN connection control part 12 and is written into a state managing table 14. Then, the IP address of the VPN device of a calling destination side is transmitted to the VPN device of a calling source side by communication by using the B2 channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a virtual leased line connection control device for controlling connection between a plurality of virtual leased line devices for constructing a virtual leased line network mainly using the Internet, and a virtual leased line connection control device therefor. About the method.

[0002]

2. Description of the Related Art In the prior art, a virtual private line network (hereinafter abbreviated as a VPN (Virtual Private Network)) has been constructed as follows. A VPN device is installed at each of a plurality of bases, and a communication address of each VPN device is held in advance as management information. Also, each VP
The N device can be connected to the Internet through a nearby access point. Then, according to the network topology information defined in advance, the calling VPN device specifies the communication address of the call destination and establishes a connection via the Internet, thereby enabling communication via the VPN. It should be noted that the communication between the above VPN devices is based on I
This is performed by P (Internet Protocol), and an IP address is used as a communication address.

[0003]

SUMMARY OF THE INVENTION IS using a public network
In a communication environment where a dial-up connection is made to a P (Internet service provider), a fixed IP address is not allocated in advance, but
At the time of dial-up connection, for example, DHCP (Dynamic Ho
st Configuration Protocol)
Addresses are often assigned.
The purpose of such dynamic address assignment is to effectively utilize the space of a limited IP address (global IP address) and to reduce the labor and cost for address management on the ISP side. .

[0004] However, in the above prior art, each VP
Since it is assumed that the IP address of the N device is held in advance, there is a problem that a VPN can be constructed only in a communication environment where a fixed IP address can be assigned to the VPN device. Therefore, there is a need for a VPN device that can be used even in a communication environment such as a dial-up connection where the IP address is not fixed in advance.

The present invention has been made in view of the above circumstances, and enables connection between VPN devices even in a communication environment in which IP addresses are dynamically allocated, such as Internet connection by dial-up. It is an object of the present invention to provide a virtual private line network connection control method, a virtual private line network connection control device, and a virtual private line network connection system.

[0006]

In order to solve the above-mentioned problems, a virtual private line network connection control device according to the present invention provides a connection of a virtual private line network connection system constituted by a plurality of virtual private line network devices. What is claimed is: 1. A virtual private line network connection control device for controlling, comprising: a management table holding communication addresses dynamically allocated to said virtual private line devices; and a communication table dynamically allocated to each of said virtual private line devices. A virtual device for controlling connection by receiving an address, writing the address in the management table, reading the communication address of the virtual leased line device of the call destination from the management table, and notifying the virtual leased line device of the call source. A dedicated line network connection control unit.

Further, in the virtual private line network connection control device according to the present invention, the virtual private line network device performs communication using a plurality of communication channels on the telephone subscriber line, and uses the first communication channel among them. The second communication channel is used for transmitting application data by connecting to a public data communication network, and the other second communication channel is used for connection control including notification of the communication address. Holding a telephone number for communication of the virtual leased line device using the second communication channel, wherein the virtual leased line connection control unit sets the first communication channel to the public communication line. In order to notify an instruction to connect to a data communication network to the virtual leased line device of the call destination, the telephone number of the virtual leased line device of the call destination is set. The communication address read out from the management table is passed to the virtual leased line device on the center side, and the communication address dynamically allocated to the virtual leased line device at the call destination is received from the virtual leased line device on the center side. In order to notify the communication source address of the virtual leased line device of the call destination to the virtual leased line device of the call origin from the virtual leased line device of the call destination. The connection is controlled by reading out the communication address of the caller and the telephone number of the virtual leased line device of the caller and passing it to the virtual leased line device on the center side. Here, the plurality of communication channels on the telephone subscriber line are, for example, ISDN (Integrated Services Digit).
tal Networks (Integrated Digital Services Network). For example, in the case of a “2B + D” configuration in which two B channels and one D channel are accommodated for each subscriber line, one of the two B channels is used as the first communication channel. Then, another B channel can be used as the second communication channel. When the number of usable communication channels is larger, for example, in the case of “23B + D” composed of 23 B channels and one D channel, a plurality of B channels are used as the first communication channel. A channel may be assigned, or a plurality of B channels may be assigned as the second communication channel. Here, a typical example of the public data communication network is the Internet. Because these public data networks can be used at relatively low cost,
When this is used to construct a virtual leased line network, it is possible to realize a cheaper implementation than when actually leased a leased line.

The virtual private line network connection control device according to the present invention further includes a virtual private line network connection monitoring unit for monitoring a connection state of the virtual private line network device to which a connection has been established, When there is a virtual leased line device whose disconnection is detected by the virtual leased line connection monitoring unit, the connection control unit executes a procedure for controlling the connection again with respect to the disconnected virtual leased line device. It is characterized by.

Further, the virtual private line network connection control device according to the present invention is provided with a network topology table that holds a relationship between the virtual private line network device of a call originator and a call destination in a virtual private line network connection. The virtual private line network connection control unit executes a procedure for controlling a connection with respect to only the virtual private line network device of the call destination included in the data of the network topology table.

A virtual private line network connection system according to the present invention is constituted by a plurality of virtual private line network devices that mutually transmit application data by designating a communication address of a partner in a public data communication network. A virtual private line network connection system for connecting to a public data communication network using a first communication channel of a telephone subscriber line, and setting up a virtual private line network call on the public data communication network. A plurality of virtual leased line network devices for transmitting the application data and performing communication for connection control including notification of the communication address using a second communication channel of a telephone subscriber line; A communication address of the public data communication network dynamically allocated to the network device and the second communication address of the virtual leased line network device; A virtual table for holding a telephone number for communication using a channel, and an instruction to connect to the public data communication network using the first communication channel; To notify the telephone number of the virtual leased line device of the call destination from the management table and pass the telephone number to the virtual leased line device on the center side. Receiving the communication address dynamically allocated to the call destination virtual leased line device, writing the communication address in the management table, and calling the call destination virtual leased line device to the call destination virtual leased line device. The communication address of the virtual leased line device of the call destination and the telephone number of the virtual leased line device of the call source are read from the management table to notify the communication address of the center. A virtual leased line connection control device that controls connection by passing the data to the virtual leased line device, wherein the virtual leased line device on the center side uses the first communication channel to perform the public data communication. The telephone number of the call destination virtual leased line apparatus is received from the virtual leased line network connection control device to notify the instruction to connect to the network to the call destination virtual leased line apparatus. In this case, the communication for the telephone number is set using the second communication channel, this instruction is notified, and the communication address dynamically allocated to the virtual leased line device of the call destination is set to the virtual address. When the communication address is received from the leased line network device, the communication address is passed to the virtual leased line network connection control device, and the virtual leased line device is called from the virtual leased line connection control device to the call source virtual leased line device. Virtual only When the communication address of the virtual leased line device of the call destination and the telephone number of the virtual leased line device of the caller are received from the management table to notify the communication address of the line network device, The communication for the telephone number is set using the second communication channel, and the communication address of the virtual leased line device of the call destination is notified.

Further, in the virtual private line network connection system according to the present invention, the virtual private line network connection control device includes:
The connection state of the virtual leased line device to which the connection has been established is monitored, and when the virtual leased line device whose connection has been cut off is detected, the connection is again controlled with respect to the disconnected virtual leased line device. It is characterized by performing the following procedure.

In the virtual private line network connection system according to the present invention, the virtual private line network connection control device includes:
A network topology table that holds a relationship between the call originator and the call destination of the virtual leased line network device in the virtual leased line network connection; and the call destination virtual leased line included in the data of the network topology table. It is characterized in that a procedure for controlling the connection is executed only for the network device.

Further, the virtual private line network connection control method according to the present invention is capable of using the first communication channel and the second communication channel and designating the communication address of the other party on the public data communication network. A virtual leased line connection system comprised of a plurality of virtual leased line devices that mutually transmit application data and a virtual leased line connection control device that controls connection between these virtual leased line devices. In the private line network connection control method, a virtual private line network connection control device reads out the telephone number of the virtual private line device to be called from a management table held by the virtual private line network connection control device, and stores the telephone number in the virtual line on the center side The telephone number is passed to the leased line apparatus, and the virtual leased line apparatus at the center side receiving the telephone number uses the second communication channel to correspond to the telephone number. A first step of setting up communication, and the virtual private line network device at the center side transmits the public data communication network to the virtual private line device of the call destination through the second communication channel. A second step of giving an instruction to connect to the public data communication network using the first communication channel. The process of 3,
A communication address in the public data communication network dynamically allocated to the calling-side virtual leased line device,
The calling-side virtual leased line device notifies the virtual leased line connection controller via the center-side virtual leased line device, and the virtual leased line connection controller receiving the notification notifies the virtual leased line connection controller. The fourth to write this communication address in the management table
And the virtual private line connection controller reads out the telephone number of the virtual private line device of the calling source and the communication address of the virtual private line device of the call destination from the management table, and Handover to the virtual leased line network device on the side, and the virtual leased line network device on the center side receiving the
A fifth step of setting up a call for the telephone number using the communication channel of (a) and notifying the call source virtual leased line device of the communication address of the call destination virtual leased line device; The virtual leased line device of the caller receiving this notification sets up a call between the virtual leased line device of the call destination on the public data communication network using the communication address. And a process of

Further, in the virtual private line network connection control method according to the present invention, the virtual private line network connection control device monitors a connection state of the virtual private line device to which a connection has been established, When there is a virtual leased line device whose disconnection is detected in the connection monitoring process, the virtual leased line connection control device has a reconnection process of controlling connection again with respect to the disconnected virtual leased line device. It is characterized by.

Further, the virtual leased line connection control method according to the present invention provides a method of controlling a virtual leased line connection in a network topology table which holds a relationship between a virtual leased line device of a call originator and a call destination in a virtual leased line connection. The procedure of the first to sixth steps is executed only for the virtual leased line network device of the call destination included.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, in a dial-up connection environment where the IP address is not fixed, the VP
In order to make N connections, one of the plurality of VPN devices is positioned as a center-side VPN device, and the center-side VPN device has a table for managing the telephone number, IP address, and connection / disconnection flag of each VPN device. A VPN connection control device is also provided. For example, in a company that establishes a VPN connection, a center-side VPN device is installed in a head office, and other base-side VPN devices are installed in a branch, a business office, or the like.

The procedure for VPN connection with this configuration is as follows. (1) Using the B2 channel of the ISDN line, a connection request is made from the center-side VPN device to the site-side VPN device. (2) Upon receiving the request, the base-side VPN device issues a connection request to the ISP connection device by dial-up, and sends the IP address notified from the ISP connection device to the VPS via the center-side VPN device.
Notify the PN connection control device. (3) The VPN connection control device records the IP address notified from each site-side VPN device in a table. (4) The VPN connection control device includes:
The IP address of the VPN device to which each VPN device is connected is transmitted to each VPN device, and the VPN device that receives this transmits a connection to the IP address from the VPN connection control device to establish a VPN connection. (5)
After the connection is completed, the VPN connection control device monitors the connection status of each VPN device. If the connection is disconnected for any reason, the VPN connection control device performs the connection procedure shown in the above (1) to (4) for that VPN device. Execute and rebuild the connection.

FIG. 1 is a configuration diagram showing a configuration of a VPN connection system (virtual leased line network connection system) according to the present embodiment. In FIG. 1, reference numerals 20a and 20b denote VPN devices (virtual leased line network devices) on the center side and the base side, respectively, and reference numerals 30a and 30b denote VPN devices 20 respectively.
ISDN subscriber lines connected to a and 20b. A plurality of channels are logically accommodated in the subscriber line 30a by a time-division multiplexing method.
A channel 31a (first communication channel) and a B2 channel 32a (second communication channel) are included. Similarly, the subscriber line 30b includes a B1 channel 31b and a B2 channel 32b. 75 is I
An SDN network 76 is an IP connection service for connecting to an ISP or the like using a subscriber line, and 77 is the Internet (public data communication network). Reference numerals 60a and 60b denote ISP connection devices for connection from the center side and the base side, respectively.

In the configuration shown in FIG.
The PN device 20a is connected to the ISP using the B1 channel 31a.
Of the VPN device 20 on the site side.
b is the ISP connection device 6 using the B1 channel 31b.
0b. Thus, communication between the VPN devices 20a and 20b becomes possible via the route 21 via the Internet 77. Also,
The respective VPN connection devices can communicate with each other via the ISDN network 75 using the B2 channels 32a and 32b.

Reference numeral 10 denotes a center-side VPN device 20a.
Is a VPN connection control device (virtual leased line network connection control device) for controlling the connection between the VPN devices. The VPN connection control device 10 has a communication interface unit 11 and a VPN connection control unit inside. 12, a VPN connection monitoring unit 13, a state management table 14 (management table), and a network topology table 15.

FIG. 2 is a table showing the data structure of the state management table 14 and an example of data. As shown in FIG. 2, the status management table 14 includes a VPN device name, an ISDN
This is tabular data having numbers, global IP addresses, and states as data items. Among these data items, the global IP address is written when the IP address allocated to each VPN device is notified to the VPN connection control device. The state is rewritten when connection / disconnection is notified from each VPN device or when a change in state is detected by the VPN connection monitoring unit 13. In the data example shown in FIG. 2, information for managing the five VPN devices A to E is held in a state management table. In this example, A is a VPN device on the center side, and B to E are VPN devices on the base side.

Next, a procedure for each VPN device to connect to all VPN devices other than itself under the control of the VPN connection control device 10 will be described. FIG. 5 is a flowchart showing the procedure.

(Step S11) In the procedure of FIG.
First, the VPN connection controller 12 of the VPN connection controller 10
Refer to the state management table 14. Then, in response to an instruction from the VPN control device 10 to the VPN device on the center side (server side), the VPN device A on the center side sends all VPN devices whose status is not “connected” (in the data example shown in FIG. 2). Performs call setup via the ISDN network using the B2 channel for the VPN devices D and E). In this case, the ISDN number obtained from the state management table 14 is used. (Step S12) Then, the VPN device A on the center side
Requests the destination VPN device to dial up to the IP connection service.

(Step S13) Upon receiving the above request, the VPN device at the base side connects to the ISP connection device by dial-up using the B1 channel. (Step S14) Then, the VPN device on the site side acquires its own global IP address from the connection device of the connected ISP. This global IP address is transmitted from the VPN device on the center side using the B2 channel from the VPN device on the base side.
The status management table 1 is notified to the PN device and further transmitted to the VPN connection control unit of the VPN connection control device 10.
4 is written. Even when the status of the VPN device on the center side is not “connection”, the connection to the connection device of the ISP is performed using the B1 channel, and the allocated global IP address is stored in the status management table. 14 is written.

(Step S15) When all VPN devices are connected to the Internet, all VPs managed in the status management table are communicated by using the B2 channel.
The global IP address of the N devices is notified to each VPN device. (Step S16) Each VPN device that has received the above notification sets a VPN tunnel for the notified IP address.

(Step S17) VPN connection monitoring unit 13
Sends monitoring signals to all VPN devices at predetermined time intervals to monitor the connection status. Then, the status item in the status management table 14 is updated as appropriate according to the situation. Here, if there is no response to the monitoring signal from any of the VPN connection devices, and it is determined that the connection is disconnected, the process returns to step S11 to execute a reconnection procedure. Also,
When a normal response to the monitoring signal is obtained, it is recognized that the device is in a normal connection state, and waits until the next monitoring signal is transmitted. In the normal connection state, through the VPN tunnel set in step S16,
VPN application data is transmitted between the VPN devices.

FIG. 6 shows that all VPNs are connected according to the above connection procedure.
FIG. 3 is a reference diagram illustrating a network topology when a connection is set between devices. In FIG. 6, A to E represent VPN monitoring devices, respectively, and the arrows connecting them represent connections between the VPN devices. Note that the base side of the arrow line is the calling source, and the leading side is the calling destination.

In the above-described method, a VPN tunnel is constructed even at a destination where there is no or very little communication traffic, for example, between offices, and a monitoring signal is sent to all VPN devices. Unnecessarily many packets are sent, and a high load is also applied to a VPN device such as a business office. Therefore, for example, a method of setting a VPN tunnel only between destinations that need to communicate, such as between a head office and a branch, between a head office and a business office, or between a branch and a business office, will be described below.

FIG. 3 is a table showing the data structure and data example of the network topology table 15 for defining the network topology. This network topology table includes a calling source VPN device name and a calling destination V
It has an item of PN device name, and holds data equivalent to a directed graph having each VPN device as a node in a table format. The nodes of the directed graph represent connections established between VPN devices. The data example shown in FIG. 3 is A (calling source) → B (calling destination), B → A, C → A, C → B, D →
A VPN is constructed by connecting A, D → B, E → A, and E → B.

FIG. 7 is a flow chart showing a procedure for making a connection only between required destinations while referring to the network topology table.

(Step S21) In the procedure of FIG.
First, the VPN connection controller 12 of the VPN connection controller 10
Refer to the network topology table 15. Then, the VPN device I which is the name of the call destination VPN device
The SDN number is obtained from the status management table 14. Then, the center-side (server-side) VPN device dials these call destination VPN devices using the B2 channel to set up a call on the ISDN network. For example, in the case of the data example shown in FIG. 3, two items “A” and “B” are included in the item of the destination VPN device name, and the ISDN numbers of these VPN devices are shown in FIG. According to the data example shown in FIG. 7, "06-4803-1111" and "06-4804-2222", respectively. Here,
From A to B, dialing using the B2 channel is performed, but since A is the center-side VPN device itself, there is no need to dial from A to A.

(Step S22) Next, the center-side VP
The N device instructs each call destination VPN device to dial up to the IP connection service. (Step S23) Based on this instruction, each call destination VPN
The device connects to the connection device of the ISP using the B1 channel. When the center-side VPN device (A) is included in the call destination VPN device as shown in FIG.
Connection from the center-side VPN device to the ISP connection device is also performed. (Step S24) Then, the VPN device that has connected to the connection device of the ISP acquires a global IP address from the ISP, and transmits the global IP address to the VPN connection control unit 12 via the VPN device on the center side. The state management table 1 is sent by the VPN connection control unit 12.
4 is written.

(Step S25) Next, the VPN connection control unit 12 refers to the network topology table 15 and manages the state of the ISDN number of the calling source VPN device for each of the calling VPN devices. While acquiring from the table 14, the global IP address of the call destination VPN device corresponding to each call source VPN device is also acquired from the state management table 14. And
The center-side VPN device dials the ISDN number of each calling source VPN device using the B2 channel, and notifies the calling source VPN device of the global IP address of the corresponding calling destination VPN device. For example, in the case of the data examples shown in FIGS. 2 and 3, the network topology table 15 includes “B” as a calling source VPN device name, and the calling destination VPN device name corresponding to the “B” is It is "A". Therefore, the center-side VPN device
Dial the ISDN number “06-4804-2222” of B written in the state management table 14 to connect to the VPN device B, and connect the global IP address “xx.
x. x ". Further, for example, regarding “D” included as a calling source VPN device name in the network topology table 15, the calling destination V corresponding to the “D”
Since the PN device names are “A” and “B”, the center-side VPN device determines the ISDN number “06-4” of the VPN device D.
"806-4444" is dialed to connect to the VPN device D, and the global IP addresses "xxxxx" and "yyyy" of the VPN devices A and B are notified. Here, the IP address is "xxx.xx."
And "yyyy", an actual address composed of specific numerical values is notified.

(Step S26) Then, each of the calling source VPN devices that have received the notification connects to the ISP connection device as necessary, and then sets up a VPN tunnel for the notified IP address. (Step S27) The VPN connection monitoring unit 13 sends out a monitoring signal to all the calling VPN devices at predetermined time intervals, and monitors the setting state. Then, the status item in the status management table 14 is updated as appropriate according to the situation. Here, if there is no response to the monitoring signal from any one of the VPN connection devices and it is determined that the connection is disconnected, the process returns to step S21 to execute a reconnection procedure.
When a normal response to the monitoring signal is obtained,
It recognizes that it is in the normal connection state and waits for the next monitoring signal transmission timing.

According to this procedure, according to the network topology table, the VP is transmitted only between the limited VPN devices.
Since an N tunnel is set up and a monitoring signal is sent only to the VPN device that is the destination of the call, there is no need to send unnecessarily many packets on the network,
The load on the PN device can be reduced. In addition, since the performance scale of the VPN device such as a business office can be reduced, the cost of the entire system can be suppressed.

FIG. 8 is a reference diagram showing a network topology when a connection is established only between VPN devices defined in the network topology table by the connection procedure. As shown in FIG. 8, from the VPN device A only to B, similarly from B to A only, and also to C, D, E
, Calls are made only to A and B respectively.

Next, a method for further restricting the setting of the VPN connection according to a predetermined time schedule will be described. Note that this method is used for 24 hours 36 hours for all connections defined in the network topology table.
This is useful when you do not need to set up a full five-day call.
FIG. 4 is a table showing a data structure and a data example of a state management table including an operation schedule for each VPN device as information. The state management table shown in FIG.
This is tabular data to which a schedule is added as a data item in addition to the PN device name, ISDN number, global IP address, and status. In the data example shown in FIG.
The VPN device A is scheduled to operate fully without stopping, the VPN device B is stopped on Saturday and Sunday, and the VPN devices C to E are operated only on weekdays during the day shift. Then, the VPN connection control unit 12 refers to the information of the calendar function and the clock function built in the VPN connection control device 10 to connect the VPN device to be operated according to the schedule defined in the state management table. Such control is performed. That is, the initial startup and connection monitoring of the VPN device are performed only in the time zone in which each VPN device should operate. At the end of the time period during which operation is to be performed, a procedure for disconnecting the VPN connection is performed.

The above-described VPN connection control device includes, for example,
It is realized using a computer system. In particular,
The VPN connection control unit 12 and the VPN connection monitoring unit 13
The processing according to the procedure described with reference to FIGS. 5 and 7 is stored in the storage device of the computer system in the form of a program, and the central processing unit reads and executes the program to realize the processing. The communication interface unit 11 is realized by an input / output device of a computer system and a program for driving the same, exchanges signals with the VPN device 20a via a cable or the like, and transmits information corresponding to the signal content to a VPN connection. Control unit 1
2 and the VPN connection monitoring unit 13. And
The state management table 14 and the network topology table 15 are realized by storing data in an expression format according to the structure in a storage device of a computer system. Here, as the storage device, for example, a magnetic disk, a semiconductor memory, or the like is used.

[0039]

As described above, according to the present invention, the virtual private line network connection control device is provided with the management table for holding the communication address dynamically allocated to the virtual private line network device, and In order to notify the communication address of the leased line device from the virtual leased line connection controller to the calling virtual leased line device, it is not necessary to set fixed communication address information in advance on the calling side. A call can be set up from the caller side to the callee side, and connection to the virtual private line network can be realized. Therefore, even in a communication environment in which communication addresses are dynamically allocated such as a dial-up connection of an IP connection service, it is possible to realize a connection equivalent to a constant connection service in which a fixed communication address is allocated. Specifically, for example, it is possible to construct a virtual private line network using Internet connection by dial-up.

According to the present invention, after the connection is established, the connection state of the virtual leased line device is monitored using, for example, a monitoring packet, and if the connection is disconnected, the connection is re-established. By executing the above procedure, it is possible to realize a highly fault-tolerant virtual private line network that attempts to automatically restore a connection even when a failure occurs.

Further, according to the present invention, the virtual private line network connection control device is provided with a network topology table in consideration of the direction of connection, and the network topology table includes a call source and a call destination of the virtual private line device. In order to set up a call based on this information and to perform the above connection monitoring only for the virtual leased line device defined as the call destination in this table, the monitoring signal is minimized. And reduce the load on the virtual leased line equipment,
By eliminating unnecessary packet traffic,
It is possible to realize a virtual private line network for performing data transfer with even higher effective efficiency.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a VPN connection system according to an embodiment of the present invention.

FIG. 2 is a table showing an example of a data structure and data of a state management table (14) provided in the VPN connection control device according to the embodiment.

FIG. 3 is a table showing an example of a data structure and data of a network topology table (15) provided in the VPN connection control device according to the embodiment.

FIG. 4 is a table diagram showing another example of a data structure and data of a state management table (14) provided in the VPN connection control device according to the embodiment.

FIG. 5 is a flowchart showing a procedure of VPN connection control according to the embodiment.

FIG. 6 is a reference diagram showing a network topology when a connection is established between all VPN devices according to the embodiment.

FIG. 7 is a flowchart showing a procedure for making a connection only between required terminals with reference to a network topology table according to the embodiment.

FIG. 8 is a reference diagram illustrating an example of a network topology when a connection is set only between VPN devices defined in a network topology table according to the embodiment.

[Explanation of symbols]

 Reference Signs List 10 VPN connection control device 11 Communication interface unit 12 VPN connection control unit 13 VPN connection monitoring unit 14 Status management table 15 Network topology table 20a, 20b VPN device 30a, 30b Subscriber line 31a, 31b B1 channel 32a, 32b B2 channel 60a, 60b ISP connection device 75 ISDN network 76 IP connection service 77 Internet

Continued on the front page (72) Inventor Satoshi Okumura 3-15 Babacho, Chuo-ku, Osaka City, Osaka Inside Nippon Telegraph and Telephone Corporation (72) Inventor Katsuhiko Sato 3-15, Babacho, Chuo-ku, Osaka City, Osaka F-term (reference) 5K024 AA61 CC09 CC10 GG01 GG03 GG05 5K030 GA00 HA08 HC01 HC05 HD09 KA05 KA14 MB01 5K101 KK02 KK16 LL03 LL05 MM07 PP03 QQ13 SS07 TT06 UU16

Claims (10)

[Claims] 1. A virtual private line network connection control device for controlling connection of a virtual private line network connection system constituted by a plurality of virtual private line network devices, wherein the virtual private line network connection control device is dynamically allocated to the virtual private line network device. A management table for holding a communication address; a communication address dynamically allocated to each of the virtual leased line devices; receiving and writing the communication address in the management table; A virtual leased line connection control unit that controls connection by reading from a management table and notifying the virtual leased line device of the calling source. 2. The virtual private line network device performs communication using a plurality of communication channels on a telephone subscriber line, and connects application data by connecting a first communication channel of the plurality of communication channels to a public data communication network. The communication table is used for transmission, and another second communication channel is used for connection control including the notification of the communication address. The management table includes a second communication channel of the virtual leased line device.
The virtual private network connection control unit issues an instruction to connect the first communication channel to the public data communication network. In order to notify the virtual leased line device of the call destination, the telephone number of the virtual leased line device of the call destination is read from the management table and passed to the virtual leased line device of the center side, Receiving a communication address dynamically allocated to the virtual leased line device of the call destination from the virtual leased line device and writing the communication address in the management table,
The communication address of the virtual leased line device of the call destination and the call source are transmitted from the management table to notify the virtual leased line device of the call source of the communication address of the virtual leased line device of the call destination. 2. The virtual private line network connection control device according to claim 1, wherein the connection is controlled by reading out the telephone number of the virtual private line network device and passing the telephone number to the virtual private line device on the center side. . 3. A virtual leased line connection monitoring unit for monitoring a connection state of the virtual leased line device to which a connection has been established, wherein the virtual leased line connection control unit includes the virtual leased line connection monitoring unit. 3. The virtual private network device according to claim 1 or 2, wherein when there is a virtual private network device whose disconnection is detected by the virtual private network device, a procedure for controlling connection again with respect to the disconnected virtual private network device is executed. Dedicated line network connection controller. 4. A network according to claim 1, further comprising a network topology table for maintaining a relationship between the call originator and the call destination of the virtual leased line device in the virtual leased line network connection. 4. The virtual private line network connection control according to claim 1, wherein a procedure for controlling connection is performed only for the virtual private line network device of the call destination included in the data of the topology table. apparatus. 5. A virtual leased line connection system comprising a plurality of virtual leased line devices mutually transmitting application data by designating a communication address of a partner in a public data communication network, Connecting to the public data communication network using a first communication channel of a telephone subscriber line, setting up a virtual private line call on the public data communication network and transmitting the application data, A plurality of virtual leased line devices that perform communication for connection control including notification of the communication address using a second communication channel of a private line, and the public leased line device dynamically allocated to the virtual leased line device. A communication address of a data communication network and a telephone number for communication of the virtual leased line device using the second communication channel are held. A virtual private line network device of the call destination for notifying the virtual private line network device of the call destination of an instruction to connect to the public data communication network using the first communication channel. The telephone number of the network device is read out from the management table and passed to the virtual leased network device on the center side, and dynamically transmitted from the virtual leased network device on the center side to the virtual leased network device on the call destination. Receiving the communication address allocated to the virtual private line network device of the caller and notifying the communication address of the virtual private line network device of the call destination to the virtual private line device of the call origin. The connection is controlled by reading out the communication address of the virtual leased line device of the call destination and the telephone number of the virtual leased line device of the caller and passing them to the virtual leased line device of the center side. A virtual private line network connection control device that performs connection to the public data communication network using the first communication channel. When the telephone number of the virtual private line device of the call destination is received from the network connection control device to notify the virtual private line device of the call destination, the second communication channel is used. The communication for the telephone number is set and this instruction is notified. When the communication address dynamically allocated to the virtual leased line device of the call destination is received from the virtual leased line device, the communication is performed. Passing an address to the virtual leased line connection controller, and notifying the virtual leased line device of the caller of the communication address of the virtual leased line device of the call destination from the virtual leased line connection controller. Above When the communication address of the virtual leased line device of the call destination and the telephone number of the virtual leased line device of the call source are received from the management table, the telephone number is used using the second communication channel. A virtual private line network connection system, wherein communication is set up to notify a communication address of the virtual private line network device of the call destination. 6. The virtual private line network connection control device monitors a connection state of the virtual private line device to which a connection has been established, and detects the disconnected virtual private line device when the connection is disconnected. 6. The virtual private line network connection system according to claim 5, wherein a procedure for controlling connection of the disconnected virtual private line network device again is executed. 7. The virtual private line network connection control device includes a network topology table that holds a relationship between a virtual private line network device of a call originator and a call destination of a virtual private line network connection, 7. The virtual private line network connection system according to claim 5, wherein a procedure for controlling connection is performed only with respect to the virtual private line network device of the call destination included in the data of the topology table. 8. A plurality of virtual dedicated stations which can use a first communication channel and a second communication channel and mutually transmit application data by specifying a communication address of a partner on a public data communication network. A virtual private line connection control method in a virtual private line connection system comprising a network device and a virtual private line connection controller for controlling connection between these virtual private line devices, comprising: The network connection control device reads out the telephone number of the virtual leased line device at the call destination from the management table held by itself, passes the telephone number to the virtual leased line device on the center side, and receives this telephone number. A first step in which the virtual leased line network device on the center side sets up communication for this telephone number using the second communication channel; A second step in which the virtual leased line device instructs the virtual leased line device of the call destination to connect to the public data communication network through the second communication channel; A third step in which the virtual leased line device on the calling side that has received the instruction is connected to the public data communication network using the first communication channel; and a virtual leased line device on the calling side. A communication address in the public data communication network dynamically allocated to
The calling-side virtual leased line device notifies the virtual leased line connection controller via the center-side virtual leased line device, and the virtual leased line connection controller receiving the notification notifies the virtual leased line connection controller. The fourth to write this communication address in the management table
And the virtual private line connection controller reads out the telephone number of the virtual private line device of the caller and the communication address of the virtual private line device of the call destination from the management table, and Handover to the virtual leased line network device on the side, the virtual leased line device on the center side receiving the call sets up a call for the telephone number using the second communication channel, and A fifth step of notifying the network apparatus of the communication address of the virtual private line apparatus of the call destination, and the virtual private line apparatus of the caller receiving the notification using the communication address. A sixth step of setting up a call with the virtual leased line device of the call destination on the public data communication network. 9. A connection monitoring step in which the virtual leased line connection control device monitors a connection state of the virtual leased line device to which a connection has been established, and a virtual leased line whose disconnection has been detected in the connection monitoring step. 9. The method according to claim 8, further comprising, if there is a network device, the virtual private line network connection control device reconnecting the disconnected virtual private line network device to control the connection. Virtual private line network connection control method. 10. The virtual leased line device of a call destination included in data of a network topology table that holds a relationship between a virtual leased line device of a call originator and a call destination in a virtual leased line connection. 10. The virtual private line network connection control method according to claim 8, wherein the procedures of the first to sixth steps are performed only for the first and second steps.