JPH10257102A - Lan system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the call tariff of a high speed line by switching a line to a line by a backup means when communication cannot be executed between a private branch communication network(LAN) so as to properly cope with the generation of a fault or busyness on an exchanging line. SOLUTION: At the time of receiving the signal of a line connecting fault from an integrated services digital network(ISDN) 5 or when a line is not connected in a fixed time, a line state monitoring part 12 switches the line to a radio packet line, transmits a signal to an X.25 protocol control part 13 to convert data from LAN 6 to LAN 7 to an X.25 packet which can be transmitted as packet exchange to transmit from a radio packet exchange 14 to an inter- LAN connector 2 through a radio packet exchange 15. When data to transmit to LAN 7 from LAN 6 is generated again after the lapse of a fixed time, connection control is executed by ISDN 5 to connect between LAN 6 and 7 through ISDN 5 when the line is restored and to connect the line to a radio packet line when the line is not restored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to two LANs.
The present invention relates to a LAN system for connecting between (premise communication networks) via a high-speed line such as an ISDN (high-speed line using an integrated digital communication network). In particular, the high-speed line is backed up by using another line such as a wireless packet line. The present invention relates to a LAN system having means.

[0002]

2. Description of the Related Art Conventionally, there are a circuit switching system and a packet switching system as data switching systems of a data communication network. The circuit switching method is a switching method typified by a telephone, in which a communication line is set in advance before users actually exchange data, and a usage fee is charged according to a time when the line is connected. You. In the above-described circuit switching system, a charging service based on connection time can be received. On the other hand, in the packet switching system, information to be transmitted is firstly divided into appropriate lengths, and stored and transferred in a network in units of packets each having control information such as a destination attached thereto. You will be charged. In the packet switching system, a pay-as-you-go service is available.

[0003] As a public packet switching network protocol, ITU-T (International Telecommunication Union) recommendation X.25 is known. This ITU-T recommendation X.25 specifies a protocol between a packet terminal and a public packet switching network, and specifies a network access protocol to be protected by a user using a public packet. The basic interface, which is the smallest interface specified by ISDN, consists of two information transmission channels (B channels) and one signal transmission channel (D channel) (2B).
+ D). For example, NTT's ISDN
The service provides a basic interface called an INS (Advanced Information Communication System) net 64;
There are two types that provide a high speed or multiplex interface called the INS Net 1500.

[0004] The INS net 64 provides two 64 kbps information channels (B channels) and one 64 kbps signal channel (D channel) in the form of (2B + D). The B channel is for circuit switching and packet switching services, and the D channel is for packet switching and switching control. On the other hand, the INS net 1500 provides 23 64 kbps information channels (B channels) and one 64 kbps signal channel (D channel) in the form of (23B + D). Also be used as six B channels collectively 384kbps information channel (H ₀ channel). Or,
It can be used as all channels 1536kbps information channel (H ₁ channel). However, when using the H ₁ channel is needed separately D channel. The H ₀ channel and the H ₁ channel are
Both are line channels.

[0005] When connecting between LANs via a switched line, a method of connecting the line only when data communication is necessary is adopted due to the merit of the fee structure of the switched line. For this reason, when control information is needed periodically as in dynamic routing, communication lines are always connected, so that static routing is used instead of using dynamic routing. As the dynamic routing, generally, R
IP (Routing Information Protocol) is used and L
Control information such as the shortest path on the target network and the number of pops to the target network is transmitted from the inter-AN connecting device to the other inter-LAN connecting device on a regular basis. When the control information changes in the network configuration, the contents of the routing table are updated according to the situation, so that the LAN-to-LAN connecting device can always know the shortest communication route. On the other hand, in the static routing, route information to a network is set in advance in a LAN connection device, and communication is performed by a fixed route.

However, a LAN using a switched line
When a fault or busy occurs on the switched line when the connection is established, the LAN-to-LAN connecting device cannot flexibly cope with it because there is no means to know it.
Switching to the backup line is not possible unless the routing information set in the interconnecting device is changed. Usually, lines that require backup use a dedicated line for dynamic routing in many cases. However, if the normal communication traffic is small and a large amount of data is generated only when an event occurs, Using a dedicated line is costly.

[0007] Therefore, when performing LAN-to-LAN connection via a switching line, an IS that enables the use of dynamic routing and connects the communication line only during data communication.
A LAN system using a DN has been disclosed (Japanese Unexamined Patent Application Publication No.
-154428). This is, as shown in FIG.
The LAN-to-LAN connecting apparatus 1 uses the switched line of the ISDN 5 only when data communication is necessary, and transmits the dynamic routing control information using the packet switching of the ISDN 5, thereby enabling the dynamic routing in the ISDN LAN-to-LAN communication. It was made possible.

[0008]

However, in the above-mentioned prior art, since dynamic routing is used for communication between LANs, packets are exchanged between machines constituting a network at regular intervals when a routing table is created. However, it is necessary to always check the network status based on the dynamic routing control information issued at intervals of about 30 seconds to 1 minute. Therefore, there is a drawback that communication cost for performing the above-mentioned checking work is required. In addition, when connecting a line for LAN-to-LAN communication, one
Since it is necessary to use one line for line and packet switching,
There was a problem that the line use efficiency was poor. Furthermore, since the above conventional example does not have a backup line, when a failure or busy occurs on the switched line, there is no appropriate countermeasure, and the dynamic routing is used to continue searching for the shortest communication route. There is a problem that communication costs are required.

By the way, wireless lines often used as backup lines include switched lines and packet lines as well as ground line lines. A wireless line is unsuitable for use as a regular line for LAN-to-LAN communication that involves a large amount of data at one time, but has a feature that it is resistant to disasters and the like because there is no ground equipment on the way. Therefore, it is said that a terrestrial wired line is suitable for normal LAN-to-LAN communication, but a wireless line is suitable for an emergency such as a disaster.
However, the wireless line has not been used as backup means for LAN-to-LAN communication.

The present invention has been made in order to solve the above-mentioned problems. When a LAN-to-LAN connection is made via a high-speed line such as an ISDN, the backup line is connected even if the high-speed line fails or a busy line occurs. It is intended to provide a LAN system which can be switched at a low cost, performs data communication only when necessary, and can perform communication at low cost without passing a packet of dynamic routing at the high speed line.

[0011]

According to a first aspect of the present invention, there is provided a LAN system comprising: a backup unit comprising a wireless packet line connecting two LANs;
Line state monitoring means for monitoring the connection state between the LANs and switching the line between the LANs to the line by the backup means when the connection between the LANs via a high-speed line such as ISDN is not possible. I do.

According to a second aspect of the present invention, there is provided a LAN system having a protocol control means in an inter-LAN connecting apparatus, wherein the protocol control means sets a protocol which does not cause a delay time of a line such as a mail. When the protocol passes through the LAN connection device, the data of the protocol is transmitted and received by the backup unit even when the high-speed line is normal.

[0013] A LAN system according to a third aspect of the present invention is characterized in that a high-speed line of a communication carrier different from the high-speed line is used as backup means.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, portions common to the conventional example will be described using the same reference numerals.

Embodiment 1 FIG. 1 is a block diagram of a LAN system according to Embodiment 1 of the present invention. In the first embodiment, an example will be described in which an ISDN B channel is used as a line mode as a normal data transfer line and a wireless packet line is used as backup means. In FIG. 1, a LAN 6 is connected to the inter-LAN connecting device 1 and a LAN 7 is connected to the inter-LAN connecting device 2.
And the LAN connection apparatus 1 is connected to the ISDN 5 via the line terminating apparatus 3 (hereinafter referred to as DSU),
The AN connection device 2 is connected to the ISDN 5 via the DSU 4. The ISDN 5 is the INS net 64. The LAN connection device 1 includes a LAN interface unit 8
, A B-channel protocol control unit 9, a D-channel protocol control unit 10, an address conversion unit 11, a line status monitoring unit 12, and an X.25 protocol control unit 13. The LAN connection device 2 is a device having the same configuration as the LAN connection device 1, and the configuration of the LAN connection device 2 is not shown in FIG. The LAN connection device 1 is connected to the wireless packet switch 14 and
The connection device 2 is connected to the wireless packet switch 15.

Next, in the LAN system, LA
A case where data is transmitted from N6 to LAN 7 will be described. Data sent from LAN6 to LAN7 is LA
When the data is received by the LAN interface unit 8 of the N-to-N connection device 1, the address conversion unit 11 converts the destination network address of the data into a destination telephone number set by static routing in advance, and then converts the data to a D-channel protocol control unit 10. At DSU3 via IS
Call control is performed to DN5, and LA is controlled via DSU4.
Line connection control with the N connection apparatus 2 is performed. LAN
When the line connection between the inter-connecting device 1 and the inter-LAN connecting device 2 is established, data is transmitted from the LAN 6 to the LAN 7.

Next, when data is transmitted from the LAN 6 to the LAN 7, when the line of the ISDN 5
Congested or busy, or DSU3, DSU
The case where the line connection between the inter-LAN connecting device 1 and the inter-LAN connecting device 2 cannot be established due to a failure of No. 4 or the like will be described. The line status monitoring unit 12 receives the signal of the line connection failure from the ISDN 5, or switches the line to the wireless packet line if the line is not connected for a certain period of time Tm,
A signal is transmitted to the X.25 protocol control unit 13 and the
From the LAN to the LAN 7 is converted into an X.25 packet that can be transmitted as a packet exchange, and the LAN-to-LAN connecting device 2 is transmitted from the wireless packet switch 14 through the wireless packet switch 15.
Send to When the line is switched to the wireless packet line and after a certain period of time Tn has elapsed, data to be transmitted from LAN 6 to LAN 7 is generated again. First, connection control by ISDN 5 is performed.
When the connection between the LAN 6 and the LAN 7 is made via the DN 5 and the line is not restored, as described above,
Connect the line to the wireless packet line.

When the LAN 6 receives data from the LAN 7, line control is performed in the same manner as when data is transmitted from the LAN 6 to the LAN 7, and I / O is controlled according to the line state.
The data is transmitted from the LAN interface unit 8 of the inter-LAN connecting device 2 to the LAN 6 via the SDN 5 or the wireless packet exchangers 14 and 15 by a process reverse to the above transmission.

As described above, according to the first embodiment, I
When the LAN-to-LAN connection cannot be established via ISDN due to a failure or congestion in the SDN line, a busy state, or a failure in the line terminating device, the line can be connected to a wireless packet line for transmission. When a fault or busy signal occurs on the line, it is possible to appropriately cope with the problem.
The call charge of the DN can be reduced.

Embodiment 2 FIG. 2 is a block diagram of a LAN system according to Embodiment 2 of the present invention. In this example, as in the first embodiment, an example will be described in which the ISDN B channel is used as a line mode as a normal data transfer line and a wireless packet line is used as backup means. In FIG. 2, the LAN
6 is connected to the LAN-to-LAN connection device 1 and LAN 7 is a LAN
Connected to the LAN connection apparatus 2 and the LAN connection apparatus 1
3 and connected to the ISDN 5 via the LAN connection device 2
Is connected to ISDN5 via DSU4. The ISDN 5 is the INS net 64. The LAN connection device 1 includes a LAN interface unit 8, a protocol control unit 20, a B channel protocol control unit 9, a D channel protocol control unit 10, an address conversion unit 11
, Line status monitoring unit 12 and X.25 protocol control unit 1
3 The LAN connection device 2 is connected to the LA.
This is a device having the same configuration as the inter-N connection device 1. Also, LAN
The connection device 1 is connected to the wireless packet switch 14 and
The AN connection device 2 is connected to the wireless packet switch 15.

Next, in the LAN system, LA
A case where data is transmitted from N6 to LAN 7 will be described. Data sent from LAN6 to LAN7 is LA
When received by the LAN interface unit 8 of the N-to-N connection apparatus 1, the protocol control unit 20 determines whether the protocol of the data is a protocol to be transmitted to a preset wireless packet line. If it is a protocol to be transmitted to the X.25 protocol control unit, a signal is transmitted to the X.25 protocol control unit 13, the data from the LAN 6 to the LAN 7 is converted into an X.25 packet that can be transmitted as a packet exchange, and the radio packet exchange 14 To the LAN-to-LAN connection device 2 via If the protocol of the data is not a protocol for transmission to the wireless packet line, the address conversion unit 11 converts the destination network address of the data to a destination telephone number set by static routing in advance, and then controls the D channel protocol. In part 10,
Call control is performed on the ISDN 5 via the DSU 3, and line connection control with the inter-LAN connecting device 2 is performed via the DSU 4.

Next, when data is transmitted from the LAN 6 to the LAN 7, the line of the ISDN 5
A case where line connection between the inter-LAN connecting device 1 and the inter-LAN connecting device 2 cannot be performed due to congestion, busy, a failure of the DSU 3 or the DSU 4, or the like will be described. The line status monitoring unit 12 receives the signal of the line connection failure from the ISDN 5 or, if the line is not connected for a certain period of time Tm, transmits the data protocol to a wireless packet line that has been certified in advance by the protocol control unit 20. A signal is transmitted to the X.25 protocol control unit 13 regardless of whether the protocol is
7 is converted into an X.25 packet that can be transmitted as a packet exchange, and transmitted from the wireless packet exchange 14 to the inter-LAN connecting device 2 via the wireless packet exchange 15. When the line is switched to the wireless packet line and data to be transmitted from the LAN 6 to the LAN 7 is generated again after a certain time Tn has elapsed, the connection control by the ISDN 5 is performed first, and if the line is restored, the ISDN 5
Is established between the LAN 6 and the LAN 7 via the LAN, and if the line is not restored, the line is connected to the wireless packet line as described above.

It is determined whether or not the protocol of the data is a protocol to be transmitted to a preset wireless packet line. Are determined to be unreachable, all are transmitted to the LAN 7 via the ISDN 5. The line when the LAN 6 receives data from the LAN 7 is line-controlled in the same manner as when data is transmitted from the LAN 6 to the LAN 7, and depending on the line state, the ISDN 5
Alternatively, data is transmitted via the wireless packet exchanges 14 and 15 in a reverse process to the above-described transmission.
From the LAN interface unit 8 to the LAN 6.

As described above, according to the second embodiment, a protocol is set such that the delay time of a line such as a mail does not matter, and even if the ISDN line is normal, the protocol set for the wireless packet line is set. Is transmitted and received over the wireless packet line, the wireless packet line as backup means can be used effectively, and the connection time of the LAN line is reduced, so that the ISDN communication charge can be reduced.

Embodiment 3 In the first and second embodiments, the wireless packet lines using the wireless packet switches 14 and 15 are used as the backup means. However, as shown in FIG. 3, the ISDN 5A of a communication carrier different from the ISDN 5 is used. May be used as backup means. 3, the LAN 6 is connected to the inter-LAN connecting device 1, the LAN 7 is connected to the inter-LAN connecting device 2, and the inter-LAN connecting device 1 is connected via the DSU 3 to the IS.
The LAN 5 is connected to the ISDN 5A via the DSU 3A, and the LAN connection device 2 is connected to the ISDN 5A via the DSU 4
5, is connected to ISDN 5A via DSU 4A. The LAN connection device 1 includes a LAN interface unit 8
, A protocol controller 20, a B-channel protocol controller 9, 9A, and a D-channel protocol controller 1.
0, 10A, an address conversion unit 11, and a line state monitoring unit 12. It should be noted that the LAN connection device 2 is
This is a device having the same configuration as the inter-AN connection device 1.

Next, in the LAN system, LA
A case where data is transmitted from N6 to LAN 7 will be described. Data sent from LAN6 to LAN7 is LA
When received by the LAN interface unit 8 of the N-to-N connection device 1, the address conversion unit 11 converts the address of the data into a destination telephone number corresponding to the network address of ISDN5 or ISDN5A according to the state of the line. ,
For example, when using ISDN5A as a line,
Delivered to the D channel protocol control unit 10A, where the DSU 3A
Call control is performed to ISDN5A via
Line connection control with the inter-LAN connecting device 2 is performed via U4A.

When data is transmitted from the LAN 6 to the LAN 7, the line between the LAN connection device 1 and the LAN connection device 2 may be transmitted due to a line failure or congestion of the ISDN 5, a busy line, a failure of DSU3 or DSU4, or the like. The case where line connection is not possible will be described. The line state monitoring unit 12 receives the signal of the line connection failure from the ISDN 5, or when the line is not connected for a certain time Tm,
A signal is transmitted to the address conversion unit 11 and the
The address of the data to N7 is converted to a destination telephone number corresponding to the network address of ISDN5A,
The data is transmitted to the LAN-to-LAN connection device 2 via 5A. Note that the protocol control unit 20 is different from the second embodiment.
In the same manner as above, a protocol is set up so that the delay time of the line such as e-mail does not matter.
It controls transmission and reception using the line of the DN5A.

As described above, according to the third embodiment, even when there is no equipment such as a wireless packet switch, ISDN 5 of a communication carrier different from ISDN 5 is used as backup means.
By using a line using 5A, it is possible to appropriately cope with an occurrence of a failure or a busy line on the switched line.

The above-mentioned backup means is not limited to a radio packet line or a line using ISDN of another communication carrier, but may be a radio line other than the packet line or a satellite line. .

[0030]

As described above, according to the first aspect, L
The AN system includes a backup unit composed of a wireless packet line connecting two LANs, monitors a connection state between the two LANs, and executes a LAN when a connection between LANs cannot be established via a high-speed line such as an ISDN. Line condition monitoring means for switching the line between the lines to the line by the backup means, so that when a failure or a busy state occurs on the switched line, it can be appropriately dealt with, and compared with the case where dynamic routing is used. As a result, the communication charge for the high-speed line can be reduced.

Further, the LAN system according to claim 2 is
The inter-LAN connecting device is provided with a protocol control means, and the protocol control means sets a protocol which does not cause a delay time of a line such as a mail. When the set protocol passes through the inter-LAN connecting device, the high-speed line is set. Even if the communication is normal, the data of the above protocol is transmitted and received by the line by the backup means, so that the backup means can be used effectively, and the connection time of the LAN line is reduced. Can be reduced.

In the LAN system according to the third aspect, a high-speed line of a communication carrier different from the high-speed line such as the ISDN is used as a backup means. When a failure or busy occurs on the switched line, it is possible to take appropriate measures.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a LAN system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a LAN system according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a LAN system according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional LAN system.

[Explanation of symbols]

1, 2, LAN connection device, 3, 4, 3A, 4A DS
U, 5 ISDN, 5A ISDN of a communication carrier different from ISDN5,6,7 LAN, 8 LAN interface unit, 9,9A B channel protocol control unit, 1
0, 10A D channel protocol controller, 11 address converter, 12 line status monitor, 13 X.25 protocol controller, 14, 15 wireless packet switch, 2
0 Protocol control unit

Claims (3)

[Claims] 1. A LAN system in which two LANs are connected by a LAN connection device via a high-speed line such as ISDN or the like, a backup means comprising a wireless packet line connecting the two LANs, Line state monitoring means for monitoring the connection state between LANs and switching the line between LANs to the line by the backup means when the connection between LANs via the high-speed line cannot be established. LAN system. 2. An inter-LAN connecting device comprising a protocol control means, wherein the protocol control means sets a protocol which does not cause a problem of a delay time of a line such as a mail.
2. The LAN system according to claim 1, wherein when the set protocol passes through the LAN connection device, the data of the protocol is transmitted / received by the backup unit even when the high-speed line is normal. 3. The LAN system according to claim 1, wherein a high-speed line of a communication carrier different from the high-speed line is used as backup means.