JP2581469B2 - Local area network connection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local area network connecting device for connecting a plurality of local area networks by an integrated service digital network to widen the local area network.

[0002]

2. Description of the Related Art In recent years, in the field of computer networks, a plurality of local area networks (hereinafter, referred to as "local area networks") have been developed.
There is a remarkable tendency to connect “LANs” to each other and provide more advanced services to users. In a computer network composed of a plurality of LANs,
When a certain LAN is connected to another LAN located in a remote place, the two are connected via a dedicated line or a public network.

[0003] When a plurality of LANs are connected using a dedicated line, high-speed data transfer is possible, but even if data does not flow on the dedicated line, communication costs are incurred, which is uneconomical. There are drawbacks. In addition, since the connection partner (hereinafter, referred to as “the partner LAN”) is fixed, there is a disadvantage that the partner LAN cannot be flexibly changed.

On the other hand, there is a problem that a sufficiently high-speed data transfer cannot be realized in a public network. However,
In recent years, the above problem has been greatly reduced due to the spread of an integrated service digital network (hereinafter, referred to as “ISDN”) specified by the CCITT I-series recommendation. ISDN is
High-speed transmission of digital data, various transmission methods, and various communication services can be provided to subscribers.

[0005] By the way, conventionally, there is no communication cost other than the basic usage fee when a call is disconnected in a public network.
There is an effect that communication cost can be reduced. Further, in the public network, since the communication partner can be changed for each call, there is an effect that a flexible connection can be made possible. Furthermore, with the advent of ISDN, the effect that a sufficiently high-speed data transfer can be realized has been added. For this reason, when connecting a plurality of LANs, the use of ISDN has often increased the possibility of realizing low-cost and flexible communication.

Under these circumstances, various LAN-to-LAN connecting devices (generally referred to as "gateways") for connecting the ISDN to the LAN have been proposed.
In a conventionally proposed LAN-to-LAN connection device, a certain L
When an arbitrary node in the AN transmits data at the request of a user to an arbitrary host in a partner LAN connected via ISDN, for example, 64 Kb of ISDN
A circuit-switched call using a high-speed B channel called ps is used.

[0007] A conventional inter-LAN connecting apparatus transmits data supplied from a LAN in which the apparatus itself exists (hereinafter referred to as "own LAN") to a partner LA through a circuit-switched call using a B channel.
When transmitting to N, data is transmitted after establishing a circuit-switched call with the inter-LAN connecting device in the partner LAN. Further, the LAN connection device has a function of disconnecting a circuit switching call between LANs when data transfer between LANs is not performed for a predetermined period or more.

[0008] By the way, broadcast data may be frequently exchanged on the LAN even when data is not flowing according to a user's request. The broadcast data is data transferred to all hosts connected to the LAN for network management of the LAN or maintenance of a protocol on the LAN. Therefore, the broadcast data is also transmitted to another LAN connected via the ISDN. This broadcast data, although the data amount itself is small,
It has the characteristic that it often occurs frequently. If this frequently exchanged broadcast data is always transmitted to the host on the partner LAN by using a circuit-switched call on the B channel, a period premised on the disconnection function is hardly secured, and the circuit-switched call is not transmitted. The chances of being cut are extremely small.

In ISDN, a circuit-switched call using the B channel has a high data transfer rate of 64 Kbps and is charged according to the time during which the call is connected. On the other hand, the D-channel packet-switched call has a characteristic that the transfer rate is slightly lower at 16 Kbps, but is charged according to the amount of communication data. Therefore, when the amount of communication data is small, such as broadcast data, D
If the transfer is performed by a packet-switched call of the channel, the cost is rather reduced.

Therefore, the conventional inter-LAN connecting apparatus has a means for determining whether or not data received from its own LAN is broadcast data, as described in, for example, Japanese Patent Laid-Open No. 4-35440. If the data is broadcast data, a packet representing the data is transmitted by a D-channel packet switching call. As a result, when only broadcast data is transmitted and received between LANs, the D-channel packet switching call is used, thereby facilitating disconnection of the B-channel circuit switching call and reducing communication costs.

[0011]

By the way, generally, LA
In N, the management data may be transmitted in a normal data format other than the broadcast. For example, in order to check whether a specific host of the partner LAN is in a movable state, data is periodically transmitted from a predetermined host of the own LAN to a port number representing a network address of the specific host. This is the case.

In this case, in the conventional LAN connection device,
Data will be transferred using a B-channel circuit switched call. That is, as long as the data is transmitted in the normal data format, even if only the management data is transferred, it is handled in the same manner as normal data that is not the management data. Therefore, even when only the management data is transferred, a situation occurs in which the circuit-switched call is not disconnected, and the communication cost cannot be sufficiently reduced.

Further, in the conventional LAN-to-LAN connecting apparatus, when transmitting broadcast data to a partner LAN, the broadcast data is always transmitted using a D-channel packet switching call.
Therefore, when transmitting broadcast data, even when a B-channel circuit-switched call is connected, a packet is further transmitted by the D-channel, and the B-channel circuit-switched call is transmitted. There is also a disadvantage that the usage fee and the line usage fee of the D-channel packet-switched call are generated at the same time, and the communication cost is increased.

The present invention has been made in view of the above circumstances, and has as its object to provide an inter-LAN connecting apparatus capable of sufficiently reducing communication costs. That is, an object of the present invention is to enable a call to be used to be automatically selected according to the nature of data to be transmitted, and to enable transmission of data suitable for the nature of the call. It is another object of the present invention to promote the disconnection of a circuit-switched call that is hardly used and to avoid the waste of dual use of a circuit-switched call and a packet-switched call.

[0015]

According to the present invention, there is provided an inter-LAN connecting apparatus connected between a local area network having at least one node and a public network for providing circuit-switched calls and packet-switched calls. Port number storage means for registering an identification number of a specific node connected to the network to which local area network management data is periodically supplied; and wherein the circuit-switched call is connected and broadcast A monitoring timer for measuring the time during which data other than the data for the node having the identification number registered in the port number storage means is not supplied from the local area network, and instructing connection of the circuit-switched call; Route data transmitted and received between the area network and the public network. When the time measured by the monitoring timer exceeds a predetermined time, routing control means for instructing disconnection of the circuit-switched call, and data between the local area network and the routing control means. Local area network control means for transmitting and receiving, call control means for connecting and disconnecting the circuit switched call in response to a request from the routing control means,
Packet switching control means for transmitting and receiving data between the routing control means and the packet switched call, and circuit switching control means for transmitting and receiving data between the routing control means and the circuit switched call.

Further, another inter-LAN connecting device of the present invention includes:
A specific node connected between a local area network having at least one node and a public network providing circuit-switched calls and packet-switched calls, and connected to the local area network, the data being used for local area network management data. Port number storage means for registering an identification number of a node to which the data is periodically supplied, and measuring a time during which the circuit-switched call is connected and data other than broadcast data is not supplied from the local area network. A monitoring timer, instructing connection of the circuit-switched call, routing data transmitted and received between the local area network and the public network, and when the time measured by the monitoring timer exceeds a predetermined time Routing control means for instructing disconnection of the circuit-switched call, A local area network control means for transmitting and receiving data between the local area network and the routing control means; a call control means for connecting and disconnecting the circuit-switched call in response to a request from the routing control means; A packet switching control means for transmitting and receiving data between the control means and the packet switched call, and a circuit switching control means for transmitting and receiving data between the routing control means and the circuit switched call; When data is input from the local area network control means,
When the circuit-switched call is connected, the data supplied from the local area network controller is supplied to the circuit-switched controller.

Further, another inter-LAN connecting device of the present invention comprises:
A specific node connected between a local area network having at least one node and a public network providing circuit-switched calls and packet-switched calls, and connected to the local area network, the data being used for local area network management data. Port number storage means for registering an identification number of a node which is periodically supplied, and data other than data for a node which is connected to the circuit-switched call and which has broadcast data and an identification number registered in the port number storage means. A monitoring timer that measures the time when data is not supplied from the local area network, instructs connection of the circuit-switched call, routes data transmitted and received between the local area network and the public network, The time measured by the monitoring timer is a predetermined time. Routing control means for instructing disconnection of the circuit-switched call if the call has passed, a local area network control means for transmitting and receiving data between the local area network and the routing control means, and a request from the routing control means. Call control means for connecting and disconnecting the circuit-switched call in response to the packet switching control means for transmitting and receiving data between the routing control means and the packet-switched call; and the routing control means and the circuit-switched call. Circuit switching control means for transmitting and receiving data between the local area network control means, when data is input from the local area network control means, when the circuit switching call is connected, the local area The data supplied from the network control means to the circuit switching control Supplied to the stage.

Further, the method for controlling connection between local area networks according to the present invention is connected between a local area network having at least one node and a public network for providing circuit-switched calls and packet-switched calls. Port number storage means for registering an identification number of a node which is connected to the specific node and to which the local area network management data is periodically supplied; and A monitoring timer for measuring the time during which data other than data for the node having the identification number registered in the port number storage means is not supplied from the local area network; and instructing connection of the circuit switched call, Sent and received between the network and the public network Routing control means for routing data and instructing disconnection of the circuit-switched call when the time measured by the monitoring timer exceeds a predetermined time. Comprises a circuit-switching utilization step for processing when the connection is in progress, and a line connection step for processing when the circuit-switched call is not in connection, wherein the circuit-switching utilization step includes data supplied from the local area network. Transmitting the data using the circuit-switched call, and if the data supplied from the local area network is not broadcast data and is not data for a node having an identification number registered in the port number storage means, Resetting and activating the monitoring timer, Serial line connection process includes a step of transmitting comprising the steps of newly connected to circuit-switched call, the data supplied by the newly connected circuit-switched call from the local area network,
Resetting and activating the monitoring timer.

Further, in the method for controlling connection between local area networks according to the present invention, in the line connection step, data supplied from the local area network is broadcast data or an identification number registered in the port number storage means. And transmitting only the data supplied from the local area network by the packet-switched call without newly connecting a circuit-switched call.

[0020]

According to the present invention, a LAN connection apparatus is provided for a LAN and an ISD.
A routing control unit that routes data between N lines holds a port number table in which port numbers of specific nodes are registered. One of the port numbers registered in this table is specified as a data destination. If the port numbers match, the data is also regarded as management data and supplied to the D-channel packet control unit.

Further, another inter-LAN connecting device of the present invention includes:
A routing control unit comprising connection state monitoring means for taking a value corresponding to a connection state of a B-channel circuit-switched call;
When a circuit-switched call is connected, the data supplied from the LAN control unit is supplied to the B-channel circuit-switched control unit regardless of whether the data is broadcast data.

Further, another inter-LAN connecting device of the present invention comprises:
The routing control unit includes a port number table and connection state monitoring means. The routing control unit regards data and broadcast data addressed to a specific port number as management data.
The data supplied from the AN control unit is supplied to the B-channel circuit switching control unit regardless of whether the data is management data.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the inter-LAN connecting apparatus of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, an inter-LAN connecting apparatus 1 according to an embodiment of the present invention connects a LAN 12 and an ISDN 11 in a computer system network, and controls transmission and reception of data between the two.

The LAN 12 is connected to an IEEE 802.3 CS.
DO on the Ethernet using MA / CD bus
"RFC-793" and "RFC-791" by D
It implements TCP / IP defined as This L
A host 10 and other nodes (not shown) are connected to the AN in addition to the LAN connection device 1. Each of these nodes is assigned a unique port number.

The ISDN 11 provides the LAN connection device 1 with a B channel, which is a 64 Kbps circuit-switched call, or a D channel, which is a 16 Kbps packet-switched call.
The ISDN 11 is configured to connect to the other LAN 12 via the other LAN connection device 1.

Referring to FIG. 2, an inter-LAN connecting apparatus 1 according to an embodiment of the present invention includes a D-channel call control circuit 2 for controlling a packet-switched call for connecting a circuit-switched call, and a packet-switched call. A D-channel packet switching control circuit 3, a B-channel circuit switching control circuit 4 for controlling circuit-switched calls, and an IS for controlling the physical layer of ISDN.
A DN physical layer control circuit 5, a routing control circuit 6 for controlling data routing, a port number table 7 for registering port numbers of nodes to which management data is supplied, a monitoring timer 8 for monitoring a line connection state, and It comprises a LAN control circuit 9 for controlling each data in the LAN.

The ISDN physical layer control circuit 5
It performs layer 1 processing in the N protocol model. This ISDN physical layer control circuit 5
Assemble a layer 1 frame according to data supplied from the channel call control circuit 2, the D channel packet switching control circuit 3, or the B channel circuit switching control circuit 4, and perform a B channel circuit switching call or a D channel packet switching call. And send it out. Further, the ISDN physical layer control circuit 5 decomposes the layer 1 frame supplied by the B-channel circuit-switched call or the D-channel packet-switched call of the ISDN 11 to obtain a D-channel call control circuit 2, a D-channel packet switching control circuit. 3 or to the B-channel circuit switching control circuit 4.

The D-channel call control circuit 2 performs processing of layers 2 and 3 in the ISDN protocol model. The D-channel call control circuit 2, when supplied with the telephone number of the other party to which the B-channel circuit-switched call is connected from the routing control circuit 6, switches to the D-channel packet-switched call via the ISDN physical layer control circuit 5. A packet including the call setting request addressed to the telephone number and the telephone number of the inter-LAN connecting device 1 is transmitted. Then, in response to the packet, the D-channel packet switching call and the IS
When a packet for confirming the call setting is supplied via the DN physical layer control circuit 5, the D-channel call control circuit 2 supplies data indicating that the circuit-switched call has been connected to the routing control circuit 6.

The D-channel call control circuit 2 is supplied with a packet indicating a call setup request via the D-channel packet switching call and the ISDN physical layer control circuit 5, and is using a B-channel circuit switching call. If not, IS
A packet for confirming the call setting is transmitted to the requesting LAN connection apparatus 1 via the DN physical layer control circuit 1 and the D-channel packet switching call. Then, the D-channel call control circuit 2 connects a circuit-switched call with the inter-LAN connecting device 1 that has issued the request. At this time, similar to the case described above,
The D-channel call control circuit 2 supplies data indicating that the circuit-switched call has been connected to the routing control circuit 6.

The D-channel packet switching control circuit 3
It performs layer 2 processing in the SDN protocol model. The D-channel packet switching control circuit 3 sends the data supplied from the routing control circuit 6 to the D-channel packet switching call via the ISDN physical layer control circuit 5. The D-channel packet switching control circuit 3 supplies the D-channel packet switching call and the data supplied via the ISDN physical layer control circuit 5 to the routing control circuit 6. Note that the data transmitted in the packet-switched call of the D channel is
The packet is defined by the SDN protocol model.

The B channel circuit switching control circuit 4 sends the data supplied from the routing control circuit 6 to the B channel circuit switched call via the ISDN physical layer control circuit 5. Then, the B-channel circuit switching control circuit 4
The data supplied through the circuit-switched call of the channel and the ISDN physical layer control circuit 5 is supplied to the routing control circuit 6.

The LAN control circuit 9 performs media access control, logical link control, and TCP / IP protocol control, and supplies data supplied from the LAN 12 to the routing control circuit 6. LAN control circuit 9
Represents the data supplied from the routing control circuit 6 as L
Send to AN12. Here, the data exchanged in the LAN 12 is an IP packet defined by TCP / IP, and has a different format from the packet in the ISDN. The LAN control circuit 9 has a routing information table, and controls data on the LAN 9 or data from the routing control circuit 6 based on the routing information table.

In the routing information table, two Ls
The state of the network including the AN 12 and the ISDN line 11 is recorded. Generally, a destination address included in a packet flowing through a network can be divided into a network identifier that physically identifies the network and a host identifier that identifies a device on the network. Among them, the host identifier corresponds to the above-mentioned port number. Thus, the LAN control circuit 9 can specify the LAN 12 where the destination node of the supplied data exists from the address in the packet. The LAN control circuit 9 determines that the destination node of the packet on the LAN 12 is an IS
If it exists in another LAN 12 connected via the DN line 11, the data is transmitted to the other LAN 12.
This transmission process will be described later together with the operation of the LAN-to-LAN connection device 1.

The routing control circuit 6 stores data supplied from the LAN control circuit 9, the D-channel packet switching control circuit 3, and the B-channel circuit switching control circuit 4, and controls the stored data.

The routing control circuit 6 has a function of receiving the connection state of the line of the B channel from the B channel circuit switching control circuit 4 and recognizing whether or not the B channel is being connected. As a result, the routing control circuit 6 controls the monitoring timer 8 and controls the line connection and
Control cutting.

When the data indicating that the B-channel circuit-switched call has been connected is supplied from the D-channel call control circuit 2, the routing control circuit 6 resets and starts the monitoring timer 8. The monitoring timer 8 is reset when data supplied from the ISDN 11 or data to be transmitted to the ISDN 11 is not management data, and increases the value at a sufficiently short predetermined time interval. That is,
The monitoring timer 8 counts the time when the B-channel circuit-switched call is connected and only the control data is transferred in the ISDN 11. Further, the routing control circuit 6 disconnects the B-channel circuit-switched call using the D-channel call control circuit 2 when the value of the monitoring timer 8 exceeds the preset value, that is, when the timeout occurs, and monitors the value. The operation of the timer 8 is stopped.

The routing control circuit 6 has a function of referring to the address portion of the packet and determining whether or not the data supplied from the LAN control circuit 9 is broadcast data. Generally, when all bits of the host identifier are “1”, it means that the broadcast is performed. Therefore, the routing control circuit 6 can determine that the packet is related to the broadcast by referring to the host identifier part of the address of the packet.

Referring to FIG. 3, the port number table 7
Is registered with a port number of a node to which LAN management data expressed in a non-broadcast ordinary data format is periodically supplied. Routing control circuit 6
Has a function of determining whether or not a packet destination is a node to which LAN management data is periodically supplied.
That is, the routing control circuit 6 is a specific node related to the management data by checking whether the port number of the destination of the packet matches one of those registered in the port number table 7. You can judge that.

If the result of the above determination is that the node is broadcast or is a specific node related to management data, the routing control circuit 6 regards the data supplied from the LAN control circuit 9 as management data. . At this time, if a B-channel circuit-switched call is connected, the management data is also transferred to the B-channel circuit-switched control circuit 4, the ISDN physical layer control circuit 5,
Outgoing via channel circuit switched call. On the other hand, when the B-channel circuit-switched call is disconnected, the management data is transmitted via the D-channel packet switch control circuit 3, the ISDN physical layer control circuit 5, and the D-channel packet switch call.

Next, the operation of the LAN connection device of the present invention in the above embodiment will be described with reference to the drawings.

Referring to FIGS. 2 and 4, first, when a power supply (not shown) is turned on, the LAN connection device 1 is turned on.
Is activated, and the process proceeds to step S1. In step S1, initialization is performed in the routing control circuit 6, the B-channel circuit switched call is disconnected, and the monitoring timer 8 is stopped. Next, in steps S2 to S4, an event or monitoring of data reception from any of the D-channel call control circuit 2, the D-channel packet switching control circuit 3, the B-channel circuit switching control circuit 4, and the LAN control circuit 9. The timer 8 has a time-out event. While these events do not occur, that is, the determination result in steps S2 to S4 is “N
While "O", the processing of steps S2 to S4 is repeatedly performed. Hereinafter, this repetitive processing is called an event waiting loop.

When data is supplied from the ISDN 11 via the B-channel circuit-switched call, if the B-channel circuit-switched call is disconnected, the D-channel call control circuit 2 via the ISDN physical layer control circuit 5 Is supplied, and the result of the determination in step S3 is "YES". Then, the process proceeds to step S8, where a B-channel circuit-switched call is connected to the requesting inter-LAN connecting apparatus 1. Then, in step S9, the monitoring timer 8 is reset and started, and the B-channel circuit switching control circuit 4 notifies the routing control circuit 6 that the B-channel line has been connected. Then, the process returns to the event waiting loop of steps S2 to S4.

The D-channel packet switching control circuit 3
Alternatively, when data is supplied from the B-channel circuit switching control circuit 4 to the routing control circuit 6, the result of the determination in step S2 is "YES", and the process proceeds to step S5.

In step S5, the routing control circuit 6 determines whether the data comes from the ISDN 11 or from the LAN 12.
Since the result of this determination is “YES”, that is, from the ISDN 11 side, the process proceeds to step S6, where
The data is transmitted from the LAN control circuit 9 to the LAN 12 according to the routing information.

When the monitoring timer 8 times out in the event waiting loop of steps S2 to S4, the result of the determination in step S4 is "YES",
The process returns to step S1. That is, the monitoring timer 8 is stopped, and the B-channel circuit switched call is disconnected. Further, the B-channel circuit switching control circuit 4 notifies the routing control circuit 6 that the B-channel line has been disconnected.

Next, in the event waiting loop,
When data is supplied from the LAN control circuit 9 to the routing control circuit 6, the result of the determination in step S2 is "YES".
And the process proceeds to step S5.

In step S5, the routing control circuit 6 determines whether the data comes from the ISDN 11 side or the LAN 12 side. Since the determination result is “NO”, that is, the LAN 12 side, the process proceeds to step S7. In step S7, B
It is determined whether a circuit-switched call for the channel is being connected. If the result of this determination is "NO", the process proceeds to step S30.

Referring to FIG. 5, in step S30,
Processing for new connection of the line is performed. Step S3
At 1, it is determined whether the data supplied to the routing control circuit 6 is broadcast data. If the result of this determination is "NO", the process proceeds to step S
32, where the port number of the destination of the data is
It is determined whether the port number matches one port number registered in the port number table. If the result of this determination is "NO", the process proceeds to step S33.

Steps S33 to S35 are processes in the case where the B-channel circuit-switched call has been disconnected and the data to be transmitted is not management data. Step S3
At 3, the routing control circuit 6 uses the D-channel call control circuit 2 to connect the B-channel circuit-switched call to the LAN 12 where the data destination node exists. Next, in step S34, the routing control circuit 6
Send data via connected circuit switched calls. Next, in step S35, the routing control circuit 6
The monitoring timer 8 is reset and activated. Then, the process returns to the event waiting loop (steps S2 to S
Return to 4).

On the other hand, step S31 or step S3
If the decision result in the step 2 is "YES", the process proceeds to a step S36. Step S36 is a process performed when the circuit-switched call of the B channel is disconnected and the data is management data. In step S36, the routing control circuit 6 sends data via the D-channel packet switching control circuit 3, the ISDN physical layer control circuit 5, and the D-channel packet switching call. Then, the process is an event waiting loop (steps S2 to S4).
Return to

Referring to FIG. 4, a B-channel circuit-switched call is connected, and the result of determination in step S7 is "Y".
If "ES", the process proceeds to step S20.

Referring to FIG. 6, in step 20, B
Transmission via the channel takes place. In step S21, regardless of whether the data supplied to the routing control circuit 6 is management data or not, via the D-channel packet switching control circuit 3, the ISDN physical layer control circuit 5, and the D-channel packet switching call. To transmit the data. Then, the process proceeds to step S22, where it is determined whether or not the data is broadcast data, as in step S31.

If the decision result in the step S22 is "NO", the process proceeds to a step S23. Step S23
Then, as in step S32, it is determined whether or not the port number of the destination of the data matches one port number registered in the port number table. If the result of this determination is "NO", the process proceeds to step S24. Step S24 is processing when the B-channel circuit-switched call is connected and the data is not management data. The routing control circuit 6 resets and starts the monitoring timer 8. Then, the process returns to the event waiting loop (steps S2 to S4).

On the other hand, step S22 or step S2
If the decision result in 3 is "YES", the process returns to the event waiting loop.

As described above, in the LAN connection apparatus 1 according to one embodiment of the present invention, not only broadcast data but also data transmitted periodically to a specific port number can be regarded as management data. Therefore, the chance of resetting the monitoring timer 8 is reduced, and the number of times the B-channel circuit-switched call is disconnected increases. Therefore,
The period during which the B-channel circuit-switched call is in the disconnected state can be lengthened, and the communication cost can be reduced.

Further, the LAN connection device 1 according to the present embodiment
Transmits the data using the B-channel circuit-switched call when the B-channel circuit-switched call is in the connected state, regardless of whether the data to be sent to the ISDN 11 is management data or not. At the same time, when the B-channel circuit-switched call is in a disconnected state, the management data is transmitted using the D-channel packet-switched call. That is,
There is no simultaneous use of B-channel circuit-switched calls and D-channel packet-switched calls. Therefore, communication costs can be reduced.

In the above-described embodiment, an example has been described in which a network is formed by connecting two LANs 12, but the number of LANs 12 forming the network may be two or more. Further, a B-channel packet-switched call may be used instead of the D-channel packet-switched call.

[0059]

As described above, according to the present invention,
Data addressed to a specific port number other than broadcast is also regarded as management data, and when the B-channel circuit-switched call is in a disconnected state, the data is sent to the ISDN line via the D-channel packet switching control circuit. Even if management data other than broadcast is transmitted periodically, the B-channel circuit-switched call can be disconnected. When a B-channel circuit-switched call is connected, the management data is also sent to the ISDN line via the B-channel circuit-switched control circuit, so that the D-channel packet-switched call is not used. That is, a B-channel circuit-switched call and a D-channel packet-switched call are not used simultaneously.

Therefore, there is an effect that the communication cost can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a computer network system using a LAN connection device of the present invention.

FIG. 2 is a diagram showing a configuration of an inter-LAN connection device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a port number table in one embodiment of the inter-LAN connecting apparatus of the present invention.

FIG. 4 is a diagram showing the operation of the LAN connection apparatus according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating an operation when a new channel is connected in the LAN connection apparatus according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating an operation when a B channel is used in the LAN connection apparatus according to an embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 inter-LAN connection device 2 D-channel call control circuit 3 D-channel packet switching control circuit 4 B-channel circuit switching control circuit 5 ISDN physical layer control circuit 6 routing control circuit 7 port number table 8 monitoring timer 9 LAN control unit 10 host 11 ISDN 12 LAN

Claims (5)

(57) [Claims] 1. A specific node connected between a local area network having at least one node and a public network providing circuit-switched calls and packet-switched calls, and connected to the local area network, A port number storage unit for registering an identification number of a node to which area network management data is periodically supplied; an identification number registered in the broadcast data and the port number storage unit while the circuit-switched call is being connected; A monitoring timer that measures the time during which data other than the data for the node is not supplied from the local area network; and instructs connection of the circuit-switched call, and is transmitted and received between the local area network and the public network. Route the data and time measured by the monitoring timer Routing control means for instructing disconnection of the circuit-switched call when a predetermined time has passed; local area network control means for transmitting and receiving data between the local area network and the routing control means; Call control means for connecting and disconnecting the circuit-switched call in response to a request from control means; packet switching control means for transmitting and receiving data between the routing control means and the packet-switched call; Circuit switching control means for transmitting and receiving data to and from the circuit switched call. 2. A specific node connected between a local area network having at least one node and a public network providing a circuit-switched call and a packet-switched call, wherein the specific node is connected to the local area network. Port number storage means for registering an identification number of a node to which area network management data is periodically supplied; and wherein the circuit-switched call is connected and data other than broadcast data is supplied from the local area network. A monitoring timer that measures no time, instructs connection of the circuit-switched call, routes data transmitted and received between the local area network and the public network, and measures a predetermined time measured by the monitoring timer. Routine for instructing disconnection of the circuit-switched call if the time is exceeded Control means for transmitting and receiving data between the local area network and the routing control means; and call control for connecting and disconnecting the circuit-switched call in response to a request from the routing control means. Means, packet switching control means for transmitting and receiving data between the routing control means and the packet switched call, and circuit switching control means for transmitting and receiving data between the routing control means and the circuit switched call. When the routing control means receives data from the local area network control means, the data supplied from the local area network control means is transmitted to the circuit switching control means when the circuit switched call is connected. Local area network characterized by supplying to Click between the connecting device. 3. A specific node connected between a local area network having at least one node and a public network providing circuit-switched calls and packet-switched calls, and connected to the local area network, A port number storage unit for registering an identification number of a node to which area network management data is periodically supplied; an identification number registered in the broadcast data and the port number storage unit while the circuit-switched call is being connected; A monitoring timer that measures the time during which data other than the data for the node is not supplied from the local area network; and instructs connection of the circuit-switched call, and is transmitted and received between the local area network and the public network. Route the data and time measured by the monitoring timer Routing control means for instructing disconnection of the circuit-switched call when a predetermined time has passed; local area network control means for transmitting and receiving data between the local area network and the routing control means; Call control means for connecting and disconnecting the circuit-switched call in response to a request from control means; packet switching control means for transmitting and receiving data between the routing control means and the packet-switched call; Circuit switching control means for transmitting and receiving data to and from the circuit switched call, wherein the routing control means, when data is input from the local area network control means, when the circuit switched call is connected Is the data supplied from the local area network control means. Between local area network connection device and supplying to the circuit switching control means. 4. A specific node connected between a local area network having at least one node and a public network providing a circuit-switched call and a packet-switched call, and connected to the local area network, Port number storage means for registering an identification number of a node to which the area network management data is periodically supplied; and an identification number registered in the broadcast data and the port number storage means while the circuit-switched call is being connected. A monitoring timer that measures the time during which data other than the data for the node is not supplied from the local area network; and instructs connection of the circuit-switched call, and is transmitted and received between the local area network and the public network. Route the data and time measured by the monitoring timer A routing control means for instructing disconnection of the circuit-switched call when the time exceeds a predetermined time. A circuit-switching utilization process for processing when the circuit-switched call is being connected. And a circuit connecting step of processing when the circuit switched call is not connected, wherein the circuit switching utilizing step includes transmitting data supplied from the local area network using the circuit switched call. Resetting and activating the monitoring timer when the data supplied from the local area network is not broadcast data and is not data for a node having an identification number registered in the port number storage means. The line connection step includes a step of newly connecting a circuit-switched call. Transmitting the data supplied from the local area network by the newly connected circuit-switched call; and resetting and activating the monitoring timer. Control method. 5. The line connection step, if the data supplied from the local area network is broadcast data or only data for a node having an identification number registered in the port number storage means, 5. The method according to claim 4, further comprising the step of transmitting data supplied from the local area network by the packet switched call without connecting a circuit switched call to the network.