JPH10285178A - Communication system, communication controller and communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To communicate only among terminals that belong to the group without needing to perform call control each time communication is performed and also without previously establishing a PVC(permanent virtual channel connection) in each combination of entire terminals that belong to the group on an ATM(asynchronous transfer mode) communication network. SOLUTION: When a certain terminal 1 sends data to other terminals for the first time, it is performed via a closed communication controller 3 by using a 1st PVC 8. The controller 3 establishes a temporary VC with a sending destination terminal 1 of received data and transfers the data to the sending destination terminal 1. Also, when bidirectional communication is performed between certain terminals 1, a strong point switch 2a is controlled, a 1st VC link 6 that is used for the temporary VC which is established between the terminals 1 is mutually connected and a 2nd PVC is established. After that, for the communication between the terminals 1 the 2nd PVC is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, a communication control device, and a communication terminal that enable communication between specific devices only on a communication network of an asynchronous transfer mode (ATM).

[0002]

2. Description of the Related Art Conventionally, an ATM communication network has been used as a wide area communication connection for connecting computers and LANs (Local Area Networks) at a plurality of geographically separated bases.

[0003] When an ATM communication network is used, a person who does not own a self-operated wide-area communication facility uses a communication facility of a telecommunications carrier. Therefore, since communication equipment will be shared with third parties,
It is necessary to prevent a situation in which communication is performed with a third party contrary to intention.

For this reason, on an ATM communication network, communication is performed only between terminals belonging to a specific group and communication between third parties not belonging to the group is restricted. The following methods have been proposed.

In the first method, when an originating terminal makes a connection request to a certain terminal, the ATM exchange (switch) judges whether or not to accept the request, thereby restricting the originating call and performing communication. Is a method of controlling

In a second method, when a calling terminal makes a connection request to a certain terminal, the terminal receiving the request determines whether or not the request is accepted, thereby restricting the incoming call.
This is a method for controlling communication.

[0007] A third method is to provide a fixed virtual channel connection (PV) to all terminals that permit communication.
C: Permanent Virtual Connections) is set up, and the communication of a third-party terminal that cannot use PVC is regulated.

[0008]

However, the above-mentioned first to third conventional methods have the following problems.

In the first conventional method, prior to actual communication, call control, that is, whether the connection between the calling terminal and the called terminal is performed between the calling terminal and the switch that has issued the connection request. Must be controlled.

By the way, communication protocols widely used for communication between computers are often based on connectionless procedures. Moreover, in communication between computers,
In many cases, data is transferred spontaneously and instantaneously, and communication is immediately interrupted.

Therefore, when the first conventional method is applied to communication between computers, call control is performed every time data transfer is performed, which increases overhead. In addition, the time lag from when data transfer is attempted to when data transfer is actually performed is large, and smooth data transfer cannot be performed.

In the second conventional method, prior to actual communication, call control must be performed between the transmitting terminal that has made the connection request and the receiving terminal that has received the request. Therefore, the same problem as in the above-described first method occurs.

In the third conventional method, unlike the first and second conventional methods, there is no need to perform call control prior to actual communication. Therefore, the above-described problem of overhead does not occur.

[0014] However, in the third conventional method, PVC must be established in advance for each combination of all terminals permitted to communicate.

In particular, when a new subscriber is approved, a new PVC must be established for each combination of all terminals that allow communication, including the terminal of the new subscriber. Heavy burden.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable communication only between a plurality of terminals belonging to a predetermined group on an ATM communication network. It is not necessary to perform call control every time communication is performed between terminals, and communication between terminals can be performed for each combination of all terminals belonging to the group without previously establishing a PVC. To provide a communication system, a communication control device, and a communication terminal capable of performing the communication.

[0017]

In order to solve the above-mentioned problems, a communication system according to the present invention is a communication system for performing communication only between a plurality of predetermined communication terminals on a communication network of an asynchronous transfer system. An exchange, a communication control device, a plurality of first virtual channel links set in advance between the exchange and each of the plurality of communication terminals,
A first virtual channel connection established in advance between the communication control device and each of the plurality of communication terminals, wherein the communication control device has been transmitted via the first virtual channel connection. A receiving unit that receives communication data, the communication control device, and the communication terminal that is a destination of the communication data received by the receiving unit, the first virtual channel connection that has been established in advance,
Transmitting means for transmitting the communication data, the exchange,
The available first virtual channel link is selected from a plurality of first virtual channel links set in advance with the communication terminal of the destination of the communication data received by the receiving unit. Selecting means, detecting means for detecting a pair of the communication terminals with which two-way communication has been performed via the communication control device, and, for the pair of communication terminals detected by the detecting means, from one communication terminal to the other When transmitting communication data to the communication terminal of the first virtual channel link set by the selection means, and when transmitting communication data from the other communication terminal to the one communication terminal, the Controlling the exchange so that the first virtual channel link set by the means is connected to the first virtual channel link, and establishing a second virtual channel connection between the pair of communication terminals. After the second virtual channel connection is established with the communication terminal that is a communication partner, the communication terminal performs communication using the connection. I do.

Here, the communication terminal includes not only a computer device having a communication function, but also network devices such as gateways and routers connected to a LAN or the like.

An exchange is a so-called ATM exchange (switch).

In the communication system of the present invention, when a certain terminal A transmits communication data to the terminal B for the first time, the communication data is transmitted to the first virtual channel connection previously established between the terminal A and the communication control device. To transmit to the communication control device.

In response to this, the communication control device transmits the received communication data using the first virtual channel connection established between the communication control device and the terminal B by the transmission means.

[0022] The communication control device may further include:
A usable first virtual channel link is selected from among a plurality of first virtual channel links set between the exchange and the terminal B.

Next, when the terminal B transmits communication data to the terminal A for the first time, it operates in the same manner as described above, and selects one of the plurality of first virtual channel links set between the exchange and the terminal A from the first virtual channel link. Select an available first virtual channel link.

When two-way communication is performed between the terminal A and the terminal B, the communication control device controls the exchange by the connection establishing means, and the first virtual communication between the exchange and the terminal A set by the selection means. The channel link is connected to a first virtual channel link between the exchange and the terminal B.

In this manner, a second virtual channel connection is established between the terminal A and the terminal B.

After that, the terminal A and the terminal B communicate with each other by using the second virtual channel connection.

Therefore, according to the communication system of the present invention, after bidirectional communication is performed between certain terminals, it is not necessary to perform operations such as call control every time communication is performed, so that overhead can be reduced. Can be. Also,
The time lag until data transfer is actually performed can be reduced. Therefore, smooth data transfer can be performed.

According to the communication system of the present invention, only between the communication control device and each of the terminals belonging to the group,
The first virtual channel connection may be established in advance. That is, each terminal only needs to establish one PVC in advance with the communication control device.
The burden of VC setting management can be reduced.

In the communication system of the present invention, setting means for setting a second virtual channel link between the communication control device and the exchange in the communication control device; Controlling the exchange so that the first virtual channel link is connected to the second virtual channel link set by the setting unit, and transmitting the communication control device and the communication data received by the receiving unit. Temporary connection establishing means for establishing a temporary virtual connection with the communication terminal, wherein the transmitting means transmits the communication data received by the receiving means to the first virtual channel connection. Alternatively, the temporary virtual connection established by the temporary connection establishing means may be transmitted.

The communication control device of the present invention is a communication control device connected to a communication network of an asynchronous transfer system to which a plurality of terminals are connected via an exchange, and is transmitted from a communication terminal of a transmission source. Receiving means for receiving the communication data, the exchange, and the communication terminal of the transmission destination of the communication data received by the receiving means, from among a plurality of first virtual channel links set in advance, Selecting means for selecting the usable first virtual channel link, setting means for setting a second virtual channel link between the communication control device and the exchange, and selecting the first virtual channel link selected by the selecting means. Is controlled so that the virtual channel link is connected to the second virtual channel link set by the setting unit, and is received by the communication control device and the receiving unit. The temporary connection establishing means for establishing a temporary virtual connection with the communication terminal of the transmission destination of the communication data, and the temporary virtual connection established by the temporary connection establishing means, and Transmission means for transmitting communication data, detection means for detecting a pair of the communication terminals that have performed bidirectional communication via the communication control device, and one pair of the communication terminals detected by the detection means, When transmitting communication data from one communication terminal to the other communication terminal, the communication data is transmitted from the other communication terminal to the one communication terminal and the first virtual channel link set by the selection means. At this time, the switch is controlled so that the first virtual channel link set by the setting unit is connected, and And connection establishment means for establishing a virtual channel connection between the signal terminals, characterized in that it comprises.

A communication terminal according to the present invention is a communication terminal connected to a communication network of an asynchronous transfer system to which an exchange and a communication control device are connected, wherein a plurality of virtual channels set in advance with the exchange are provided. When transmitting communication data, a storage unit storing a table in which the identification information of the link and the identification information of the communication terminal of the transmission destination assigned to the virtual channel link specified by the identification information are stored. Search means for searching the virtual channel link to which the communication terminal of the communication data is assigned from the table stored in the storage means, and the communication terminal of the communication data is assigned by the search means. If the detected virtual channel link can be detected, the communication data is transmitted to the detected virtual channel link. If the virtual channel link could not be detected, sending means for sending the communication data to a virtual channel connection set in advance between the communication control device, receiving means for receiving the communication data, The identification information about the communication terminal of the transmission source of the communication data received by the receiving unit is associated with the identification information of the virtual channel link from which the communication data has been sent, and written in a table stored in the storage unit. Writing means.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 is a schematic configuration diagram of a communication system according to an embodiment of the present invention, and FIG. 2 is a diagram showing a logical connection configuration between each node of the communication system shown in FIG.

The communication system of the present embodiment has an ATM (As
synchronous transfer mode) communication network,
This realizes communication only between communication terminals belonging to a specific group.

As shown in FIG. 1, the communication system of this embodiment includes communication terminals 1a to 1c (hereinafter, also simply referred to as communication terminals 1) belonging to a specific group on an ATM communication network, and an ATM exchange. 2a, 2b (hereinafter also simply referred to as switch 2) and a closed area communication control device 3 for controlling communication between the communication terminals 1 belonging to the group,
They are connected to each other via a communication line 4.

Here, the switch 2a is directly connected to the closed-area communication control device 3 via the communication line 4 as a site switch.

As shown in FIG. 2, a VP (Virt) is provided on a communication line 4 connecting each node (communication terminal 1, switch 2, and closed-area communication control device 3) constituting the communication system.
ualPath) link 5 is set.

Further, the first VC is provided in the VP link 5 set between the base switch 2a and each of the communication terminals 1.
(Virtual Channel) A plurality of links 6 are set,
Further, only one control VC link 7 is set in the VP link 5 set between the site switch 2a and the closed area communication control device 3.

Further, the closed area communication control device 3 and the communication terminal 1
The first PVC (Permanent Virtual Co.)
nnections) 8 are pre-established.

Here, the first VC link 6 is used to establish a second PVC between the communication terminals 1. The control VC link 7 is used by the closed area communication control device 3 to control the site switch 2a.

It should be noted that a plurality of set first VC links 6
Is accommodated in the same VP link 5 in order to determine the total bandwidth and QoS that can be used in the group by defining the band of the VP link 5 and the QoS (Quality of serves).

In this way, even when a certain communication terminal 1 belongs to a plurality of groups, it is possible to allocate the total bandwidth of the VP link and the QoS used for each group.

The first V set in the VP link 5
The number of the C links 6 may be determined in consideration of the total number of the communication terminals 1.

For example, in FIG. 2, when the second PVC can be established between all communication terminals 1, the number of first VC links 6 is the total number of combinations of two communication terminals 1. Becomes

By the way, when the number of communication terminals 1 belonging to a specific group is enormous, if the communication can be performed between all the communication terminals 1, the number of first VC links 6 also becomes enormous. On the other hand, in normal use, communication rarely occurs between all communication terminals belonging to a specific group.

Therefore, the number of the first VC links 6 is
Between all communication terminals 1 belonging to a specific group,
In fact, it may be set within a range where the second PVC is expected to be established.

The communication terminal 1 communicates with the other communication terminals 1 and the closed area communication control device 3 using the virtual channel (VC) connection established on the communication line 4.

FIG. 3 is a functional block diagram of the communication terminal 1 shown in FIG.

As shown in FIG. 3, the communication terminal 1 includes an input device 11, a display device 12, and a main body 13. The main body 13 includes a communication unit 131, a destination information storage unit 132, a communication data storage unit 133, and a control unit 134.
And.

The communication section 131 communicates with other communication terminals 1 and the closed area communication control device 3 via the VC connection established on the communication line 4.

The transmission source information storage unit 132 stores the UNI (User Network I / O) of the group to which the communication terminal 1 belongs.
4 has a connection management table shown in FIG. 4 for each VPI (Virtual Path Identify).

Here, the IP address 132b is the IP address of the transmission source of the communication data received by its own communication terminal 1.
(Internet Protocol) address.

When the communication terminal of the transmission source has a gateway function to another network such as Ethernet, only the network part of the IP address may be the IP address 132b.

The VCI value 132c is the VCI (Virtual Chan) of the VC connection from which the communication data was sent.
nel Identify) value. The IP address 132b of the transmission source of the communication data and the VCI value 132c of the VC connection used for transmitting the communication data are written in the column of the table in association with each other.

The VPI value 132a is the communication terminal 1 of its own.
Is the VPI value on the UNI of the group to which the IP address 132 belongs.
This is the VPI value of the group to which the source communication terminal 1 identified by b is subscribed.

The communication data storage unit 133 stores communication data sent from a communication partner, communication data sent to the communication partner, and the like.

The control unit 134 controls each component of the communication terminal 1 in its own.

For example, data input to the input device 11 and communication data sent from a communication partner are stored in the communication data storage unit 133. In addition, in accordance with the operator's instruction input to the input device 11, the data stored in the communication data storage unit 133 is transmitted to the communication partner or displayed on the display device 12.

The VPI and VCI are selected with reference to the connection management table of the transmission source information storage unit 132, and the VPI specified by the selected VPI and VCI is selected.
The communication data is transmitted using the C connection.

Further, the IP address of the communication terminal 1 of the transmission source included in the received communication data is associated with the VCI value of the VC connection from which the communication data has been transmitted, and the VPI value of the VC connection is set. Write to the corresponding connection management table.

FIG. 5 is a diagram showing an example of a hardware configuration of the communication terminal 1 shown in FIG.

In FIG. 5, 11a is a keyboard as the input device 11, 12a is a display as a display device, 135 is a central processing unit (CPU), 136 is a storage device such as a memory, and 137 is an ATM as a communication unit 131.
An interface 138 is a keyboard interface, and 139 is a video interface.

The storage device 136 stores a control program for operating the CPU 135 in addition to the connection management table and communication data shown in FIG.

The communication terminal shown in FIG. 3 can be realized by the CPU 135 executing the control program stored in the storage device 136.

The site switch 2a is connected to the VP link 5 or the first
The VC link 6 is managed by the port number, and the connection between the ports is changed in accordance with the instruction of the closed area communication control device 3. A commonly used ATM switch can be used for the base switch 2a and the switch 2b.

The closed-area communication control device 3 includes a site switch 2a
To establish a second PVC between the communication terminals 1 or a temporary VC connection (hereinafter referred to as a temporary VC) between the closed-area communication control device 3 and the communication terminal 1. .

FIG. 6 is a functional block diagram of the closed area communication control device 3 shown in FIG.

As shown in FIG. 6, the closed area communication control device 3 communicates with the communication unit 31, the PVC information storage unit 32, the temporary VC information storage unit 33, the link information storage unit 34, and the control unit 35. A temporary data storage unit 36.

The communication section 31 receives the communication data sent via the first PVC 8. Further, the communication data is transmitted to the communication terminal 1 using the temporary VC.

The communication data temporary storage unit 36 stores the first PV
The communication data sent via C8 is temporarily stored.

The PVC information storage unit 32 stores the first information shown in FIG.
Has a PVC management table. This table is
The first P established with the communication terminal 1 belonging to the group managed (controlled) by the own closed-area communication control device 3
VC8 is specified.

Here, the IP address 32a is the IP address of each of the communication terminals 1 belonging to the group managed by the own closed area communication control device 3. VPI / VCI32b
Is a VPI value and a VCI value that specify the first PVC 8. The IP address 32a and the IP address 32
a VPI / VCI 3 of the first PVC 8 established between the communication terminal 1 specified by a and its own closed area communication control device 3
2b is written in the column of the table in association with each other.

The temporary VC information storage section 33 has a temporary VC management table shown in FIG. This table is for specifying a temporary VC established between the own closed communication control device 3 and the communication terminal 1 belonging to the group managed by the device.

Here, the destination IP address 33a is
This is an IP address for specifying the communication terminal 1 of the transmission destination included in the communication data transmitted to the own closed area communication control device 3.

The source IP address 33b is an IP address that specifies the source communication terminal 1 included in the communication data.

The VPI / VCI 33c is a VPI value and a VCI value of a temporary VC established between the closed communication control device 3 and the communication terminal 1 of the transmission destination.

These items are written in the columns of the table in association with each other.

As shown in FIG. 9, the link information storage unit 34 has a link management table for each of the communication terminals 1 belonging to the group managed by the own closed area communication control device 3. This table shows, for each communication terminal 1 belonging to the group managed by its own closed-area communication control device 3, the usage status of the first VC link 6 set between the communication terminal 1 and the base switch 2a. For monitoring.

Here, the management target terminal IP address 34a
Is the IP address of the communication terminal 1 belonging to the group managed by the own closed communication control device 3.

The VPI / VCI 34c is the terminal to be managed IP
The VPI value and the VCI value of the first VC link 6 set between the communication terminal 1 specified by the address 34a and the site switch 2a.

The port number 34b is the VPI / VCI 34
The port number of the local switch 2a to which the first VC link 6 specified by c is assigned.

The destination terminal IP address 34d is set such that the communication terminal 1 specified by the management target terminal IP address 34a
When the first VC link 6 specified by the VPI / VCI 34c is used for communication, this is the IP address of the communication terminal 1 that is the communication partner.

These items are written in the columns of the table in association with each other.

The control unit 35 controls its own closed area communication control device 3
, And includes a temporary VC setting unit 351, a switch control unit 352, and a two-way communication confirmation unit 353.

The switch control section 352 is provided with a temporary VC
In accordance with an instruction from the setting unit 351 or the two-way communication confirmation unit 353, the setting of the site switch 2a is changed.

[0086] The temporary connection setting unit 351
With reference to the link management table stored in the link information storage unit 34, the first VC link 6 used for establishing a temporary VC is selected.

Then, a second VC link is newly set between the own closed communication control device 3 and the site switch 2a, and the second VC link and the selected first VC link are set.
An instruction is issued to the switch control unit 352 to connect the link 6.

The two-way communication confirmation unit 353 refers to the link management table stored in the link information storage unit 34 and
It is confirmed whether or not bidirectional communication has been performed between a pair of communication terminals 1 belonging to a group managed by the own closed area communication control device 3.

Then, the communication terminal 1 with which the two-way communication has been performed
In between, a first VC link 6 constituting a temporary VC used for transmitting communication data from one communication terminal 1 to the other communication terminal 1 and communication from the other communication terminal 1 to one communication terminal 1 The switch controller 352 is instructed to connect to the first VC link 6 constituting the temporary VC used for transmitting data.

FIG. 10 is a diagram showing an example of a hardware configuration of the closed area communication control device 3 shown in FIG.

In FIG. 10, reference numeral 31a denotes an ATM interface as the communication unit 31, reference numeral 37 denotes a storage device such as a memory, and reference numeral 35a denotes a central processing unit (CPU).

The storage device 37 stores, in addition to the tables and communication data shown in FIGS. 7 to 9, a control program for operating the CPU 35a.

The CPU 35a executes the control program stored in the storage device 37 to realize the closed area communication control device shown in FIG.

Next, the operation of the communication system having the above configuration will be described with reference to FIG.

FIG. 11 is a diagram for explaining the operation of the communication system shown in FIG.
FIG. 5 is a sequence diagram showing operation timings of respective units of the communication system when communication is performed between “b” and “b”.

Here, the process A shows a process in a case where communication data is transmitted from the communication terminal 1a to the communication terminal 1b when the second PVC has not been established between the communication terminal 1a and the communication terminal 1b. ing.

Process B shows a process for transmitting communication data from the communication terminal 1b to the communication terminal 1a when the second PVC has not yet been established between the communication terminal 1a and the communication terminal 1b. I have.

Process C indicates a communication process after the establishment of the second PVC between the communication terminal 1a and the communication terminal 1b.

[Processing A] Processing A is performed in the following sequence.

VC selection processing 1001 The communication terminal 1a uses the control unit 134 to store the VPI value and the VCI value corresponding to the IP address of the communication terminal 1b to be the communication partner in the connection management table stored in the transmission source information storage unit 132. Search from.

Here, if the communication terminal 1a has not yet received communication data from the communication terminal 1b, the IP address of the communication terminal 1b to be a communication partner does not exist in the connection management table.

Therefore, control unit 134 controls communication terminal 1
The VPI value and the VCI value corresponding to the IP address b cannot be detected from the connection management table.

In this case, the communication unit 131 uses the first PVC 8 established between its own communication terminal 1a and the closed area communication control device 3 to transmit communication data to its own communication terminal 1a and the communication partner. Of the communication terminal 1b together with the IP address of the communication terminal 1b.

Temporary VC selection processing 3001 Upon receiving the communication data transmitted via the first PVC 8, the closed area communication control device 3 causes the temporary VC setting section 351 to set the transmission source communication terminal included in the communication data. 1a and the IP address of the destination communication terminal 1b are obtained.

Then, the temporary VC management table in the temporary VC information storage unit 33 is searched for VPI / VCI associated with these IP addresses.

Next, the communication unit 31 transmits the retrieved VPI
The communication data received from the communication terminal 1a is transferred to the communication terminal 1b using the temporary VC specified by / VCI.

Temporary VC setting processing 3002 This processing is performed when the corresponding VPI / VCI cannot be detected from the temporary management table in the temporary VC selection processing 3001.

First, a second VC link is newly set between the closed communication control device 3 and the local switch 2a. Then, the VPI and V of the set second VC link
CI and the communication terminal 1 of the transmission source included in the communication data
a and the temporary V information of the temporary VC information storage unit 33 in association with the IP address of the destination communication terminal 1b.
Add to C management table.

Next, the link information storage unit 34 is searched for a link management table in which the IP address of the destination communication terminal 1b is the IP address of the terminal to be managed.

Next, the IP address of the source communication terminal 1a is detected from the column of the destination terminal IP address 34d of the detected link management table, and the corresponding port number and VPI / VCI are obtained.

On the other hand, if the IP address of the source communication terminal 1a cannot be detected from the column of the destination terminal IP address 34d in the detected link management table, the destination terminal IP address is determined from the link management table. Acquire an undefined port number and VPI / VCI.

The VPI / V of the selected port number
The IP address of the source communication terminal 1a is assigned to the destination terminal IP address corresponding to the CI.

After obtaining the port number and VPI / VCI from the link management table, the temporary VC setting unit 3
51 is the first specified by the obtained VPI / VCI
To the switch controller 352 so as to connect the VP link 6 with the second VC link that has been set.

In response to this, the switch control unit 352
The first VC link 6 is controlled by controlling the base switch 2a.
And the second VC link. Thereby, the temporary VC between the closed area communication control device 3 and the communication terminal 1b.
To establish.

Next, the communication section 31 transfers the communication data received from the communication terminal 1a to the communication terminal 1b by using the established temporary VC.

VC registration processing 1004 When the communication terminal 1b receives communication data from the communication terminal 1a for the first time, the communication terminal 1b associates the IP address of the communication terminal 1a of the transmission source with the VCI of the VC connection used for the communication, and The connection is added to the connection management table corresponding to the VPI of the VC connection.

[Processing B] Processing B is performed in the following sequence.

VC selection processing 1003 The communication terminal 1b uses the control unit 134 to control the VPI value and the VPI value corresponding to the IP address of the communication terminal 1a to be transmitted.
The CI value is retrieved from the connection management table stored in the transmission destination information storage unit 132.

Here, the connection management table contains:
The VPI value and the VCI value corresponding to the IP address of the communication terminal 1a are registered by the VC registration processing 1002. Therefore, the control unit 134 controls the communication terminal 1
The VPI value and VCI value corresponding to the IP address a are detected from the connection management table.

The communication unit 131 detects the detected VPI / VCI
Using the VC connection specified in this case (in this case, the temporary VC established between the own communication terminal 1b and the closed-area communication control device 3), the communication data is transmitted to the communication terminal 1a of the communication terminal 1a and the communication terminal 1a of the communication partner. It is sent together with the IP address.

Temporary VC selection processing 3003 When the closed area communication control device 3 receives the communication data transmitted via the temporary VC,
In the same manner as the selection process 3001, the temporary VC set between the closed area communication control device 3 and the communication terminal 1a is selected.

Then, using the selected temporary VC, the communication data received from the communication terminal 1b is transferred to the destination communication terminal 1a.

Temporary VC setting processing 3004 On the other hand, if no temporary VC is set between closed-area communication control device 3 and communication terminal 1a, that is, if data transmission from communication terminal 1b to communication terminal 1a is performed for the first time, In the same manner as the temporary VC setting process 3002, a temporary VC is established between the closed area communication control device 3 and the communication terminal 1a, and the temporary VC is used by using the temporary VC.
The communication data received from the communication terminal 1b is transmitted to the communication terminal 1
Transfer to a.

VC registration processing 1004 When the communication terminal 1a receives communication data for the first time from the communication terminal 1b, the communication terminal 1a associates the IP address of the communication terminal 1b of the transmission source with the VCI of the VC connection used for the communication, and The connection is added to the connection management table corresponding to the VPI of the VC connection.

[Processing C] VC connection processing 3005 The bidirectional communication checking unit 353 of the closed area communication control device 3 uses the link information storage unit 34 to set each IP address of a certain pair of communication terminals 1 as the IP address of the terminal to be managed. The two link management tables are searched, and for each of the two link management tables, the IP address of the other communication terminal paired with the communication terminal specified by the management target terminal IP address is entered in the field of the destination terminal IP address. It monitors whether it exists.

Then, when it is confirmed that the IP address of the other communication terminal of the pair exists in the column of the destination terminal IP address of each of the two link management tables, bidirectional communication is performed. I judge it.

When the above monitoring operation confirms that the two-way communication has been performed between the communication terminal 1a and the communication terminal 1b, the two-way communication confirmation unit 353 transmits the second communication between the communication terminal 1a and the communication terminal 1b. Is established.

First, the two-way communication confirmation unit 353 sends the communication terminal 1a from the link information storage unit 34
A link management table to be used as an address is selected, and VPI / VCI of a port number having the communication terminal 1b as a destination terminal IP address is detected from the link management table.

Further, a link management table having the communication terminal 1b as the IP address of the terminal to be managed is selected, and VPI / VCI of the port number having the communication terminal 1a as the destination terminal IP address is detected from the link management table.

Next, the VPI /
The switch controller 352 is instructed to connect the two first VC links 6 specified by the VCI.

In response to this, the switch control unit 352
By controlling the base switch 2a, the two first VC links 6 are connected. Thereby, the second PVC is established between the communication terminal 1a and the communication terminal 1b.

By establishing the second PVC, the temporary VC established between the closed area communication control device 3 and the communication terminals 1a and 1b is released, and the item corresponding to the temporary VC is released. Is deleted from the temporary connection management table stored in the temporary information storage unit 33.

VC selection processing 1005, 1006 After the second PVC has been established between the communication terminal 1a and the communication terminal 1b, the communication between the communication terminal 1a and the communication terminal 1b is performed in the same manner as the VC selection processing 1001, 1003. The VPI / VCI corresponding to the IP address of the communication partner is searched from the connection management table stored in the destination information storage unit 132, and the communication data is converted using the VC connection specified by the detected VPI / VCI. Send out.

As a result, communication between the communication terminal 1a and the communication terminal 1b is performed via the second PVC.

In the communication system of the present embodiment having the above-described configuration, communication between the communication terminals 1 is performed by the first PV until bidirectional communication is performed between the communication terminals 1.
The communication is performed via the closed area communication control device 3 using C8 and the temporary VC.

After the two-way communication is performed, the first VC link 6 constituting the temporary VC used when transmitting communication data from one communication terminal 1 to the other communication terminal 1 and the other, and Of the temporary VC used for transmitting communication data from one communication terminal 1 to one communication terminal 1 and the first VC link 6 constituting the temporary VC.
A VC is established, and communication between the communication terminals 1 is performed using the second PVC.

By doing so, after bidirectional communication is performed between certain communication terminals 1, it is not necessary to perform an operation such as call control every time communication is performed, so that overhead can be reduced. . Further, a time lag until data transfer is actually performed can be reduced. Therefore, smooth data transfer can be performed.

Each communication terminal 1 may establish one PVC in advance with closed-area communication control device 3,
For this reason, the burden of PVC setting management can be reduced.

Note that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention.

For example, in the above embodiment, the communication data transmitted via the first PVC 8 is transmitted to the closed area communication control device 3 between the closed area communication control device 3 and the communication terminal 1 of the transmission destination. The data is transferred to the communication terminal 1 using the established temporary VC.

However, the present invention is not limited to this.
And a first communication terminal previously established between the
May be transmitted to the communication terminal 1 using the PVC 8.

[0142]

As described above, according to the present invention,
When performing communication only between a plurality of communication terminals belonging to a predetermined group on an ATM communication network,
There is no need to perform call control every time communication is performed between communication terminals.

Further, communication between the terminals can be effectively performed without establishing a PVC for each combination of all the terminals belonging to the group.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a communication system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a logical connection configuration between each node of the communication system shown in FIG. 1;

FIG. 3 is a functional block diagram of the communication terminal 1 shown in FIG.

4 is a diagram for explaining a connection management table stored in a transmission source information storage unit shown in FIG.

FIG. 5 is a diagram illustrating an example of a hardware configuration of the communication terminal illustrated in FIG. 3;

6 is a functional block diagram of the closed area communication control device shown in FIG.

FIG. 7 is a diagram illustrating a PVC management table stored in a PVC information storage unit illustrated in FIG. 6;

FIG. 8 is a diagram for explaining a temporary VC management table stored in a temporary VC information storage unit shown in FIG. 6;

FIG. 9 is a diagram illustrating a link management table stored in a link information storage unit illustrated in FIG. 6;

FIG. 10 is a diagram illustrating an example of a hardware configuration of the closed area communication control device illustrated in FIG. 6;

FIG. 11 is a diagram for explaining the operation of the communication system shown in FIG. 1;

[Explanation of symbols]

 1a-1c Communication terminals 2a, 2b Switch 3 Closed area communication control device 4 Communication line 5 Virtual path link 6, 7 Virtual channel link 8 Virtual channel connection 11 Input device 11a Keyboard 12 Display device 12a Display 13 Main body 31, 131 Communication unit 31a, 137 ATM interface 32 PVC information storage unit 33 Temporary VC storage unit 34 Link information storage unit 35, 134 Control unit 35a, 135 CPU 36 Communication data temporary storage unit 37, 136 storage device 132 Source information storage unit 133 Communication data storage unit 138 Keyboard interface 139 Video interface 351 Temporary VC setting unit 352 Switch control unit 353 Bidirectional communication confirmation unit

Claims (5)

[Claims] 1. An asynchronous transfer communication network,
What is claimed is: 1. A communication system for performing communication only between a plurality of predetermined communication terminals, comprising: an exchange, a communication control device, and a plurality of first virtual devices set in advance between the exchange and each of the plurality of communication terminals. A channel link, and a first virtual channel connection established in advance between the communication control device and each of the plurality of communication terminals, wherein the communication control device is connected via the first virtual channel connection. Receiving means for receiving communication data, the communication control device, and the first virtual channel connection established in advance between the communication terminal to which the communication data received by the receiving means is transmitted, A plurality of the transmission means for transmitting communication data, the exchange, and the communication terminal which is a transmission destination of the communication data received by the reception means; Selecting means for selecting the usable first virtual channel link from one virtual channel link, and detecting means for detecting a pair of the communication terminals that have performed bidirectional communication via the communication control device And for the pair of communication terminals detected by the detection means, when transmitting communication data from one communication terminal to the other communication terminal, the first virtual channel link set by the selection means, When transmitting communication data from the other communication terminal to the one communication terminal, the first virtual channel link set by the setting means, so as to be connected, controlling the exchange, Connection establishment means for establishing a second virtual channel connection between the pair of communication terminals, wherein the communication terminal has a second virtual channel connection between the communication terminal and the communication terminal as a communication partner. After the virtual channel connection has been established,
A communication system for performing communication using the connection. 2. The communication system according to claim 1, wherein the communication control device sets a second virtual channel link between the communication control device and the exchange, and the selection device. A first virtual channel link selected in
The exchange is controlled so that the second virtual channel link set by the setting means is connected, and the communication control device and the communication terminal to which communication data received by the receiving means is transmitted are connected. Interim temporary connection establishing means for establishing a temporary virtual connection, wherein the sending means replaces the communication data received by the receiving means with the temporary connection instead of the first virtual channel connection. A communication system for transmitting to the temporary virtual connection established by the establishing means. 3. The communication system according to claim 1, wherein said selection means is provided for each of said plurality of communication terminals, and said plurality of said selection means are provided between said communication terminals and said exchange. Storage means for storing a table indicating a correspondence between identification information of one virtual channel link and identification information of the communication terminal assigned to the first virtual channel link specified by the identification information Retrieving the communication terminal of the transmission source of the communication data from a table of the communication terminal of the transmission destination of the communication data received by the reception unit stored in the storage unit, and associating the communication terminal with the communication terminal And selecting the first virtual channel link that has been assigned, and if the communication terminal that is the transmission source of the communication data does not exist in the table, the communication terminal is assigned. Selects the first virtual channel connections that are not,
A communication system, wherein the communication terminal as a transmission source of the communication data is assigned to the first virtual channel connection in the table. 4. A communication control apparatus connected to a communication network of an asynchronous transfer system to which a plurality of terminals are connected via an exchange, and receiving means for receiving communication data sent from a communication terminal of a transmission source. Between the exchange and the communication terminal of the transmission destination of the communication data received by the receiving means, from among a plurality of the first virtual channel links set in advance, the available first virtual channel link Selecting means for selecting a channel link; setting means for setting a second virtual channel link between the communication control device and the exchange; first virtual channel link selected by the selecting means;
The exchange is controlled so that the second virtual channel link set by the setting means is connected, and the communication control device and the communication terminal to which communication data received by the receiving means is transmitted are connected. In the meantime, temporary connection establishing means for establishing a temporary virtual connection, transmitting means for transmitting the communication data to the temporary virtual connection established by the temporary connection establishing means, and via the communication control device Detecting means for detecting the pair of communication terminals in which the two-way communication has been performed, and when transmitting communication data from one communication terminal to the other communication terminal for the pair of communication terminals detected by the detection means, And transmitting the first virtual channel link set by the selection means and communication data from the other communication terminal to the one communication terminal. Connection establishment means for controlling the exchange to establish a virtual channel connection between the pair of communication terminals so that the first virtual channel link set by the setting means is connected. A communication control device, comprising: 5. A communication terminal connected to a communication network of an asynchronous transfer system to which an exchange and a communication control device are connected, wherein identification information of a plurality of virtual channel links set in advance with the exchange, Storage means for storing a table in which identification information of the communication terminal of the transmission destination assigned to the virtual channel link specified by the identification information is stored; and a table stored in the storage means when transmitting the communication data. A search unit for searching for the virtual channel link to which the communication terminal of the communication data is assigned; and the virtual channel link to which the communication terminal of the communication data is assigned by the search unit. If it can be detected, the communication data is sent to the detected virtual channel link, and the virtual channel link is sent. If it cannot be detected, sending means for sending the communication data to a preset virtual channel connection with the communication control device; receiving means for receiving the communication data; Writing means for associating the identification information of the communication terminal as the transmission source of the communication data with the identification information of the virtual channel link from which the communication data has been transmitted, and writing the information in a table stored in the storage means. A communication terminal, comprising: