JPH10271155A - Communications system - Google Patents

Abstract

(57) Abstract: Provided is a communication system having a highly-reliable redundant configuration that enables identification of a failed individual LAN connection device. An active LAN connection device (30-1-1) connected to a LAN (20-1) connecting a destination terminal.
Is a working LAN connection device (3) for connecting a destination terminal.
0-2-1) and the standby LAN connection device (30-1-1)
2, 30-2-2) and the multicast path (50
-1, 50-2), and transmits the packet transmitted from the destination terminal to the ATM network (5-1) from the active LAN connection device (30-1-1) using the multicast path.
0) via the standby LAN connection device (30-1-1).
2) to the standby LAN-to-LAN connecting device (30-1-
2) comparing the packet received from the LAN (20-1) connecting the source terminal with the packet transferred via the ATM network (50), and based on the comparison result, the active LAN connection device; The abnormality of (30-1-1) is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for connecting a plurality of LANs (local area networks) via an ATM (Asynchronous Transfer Mode) network.

[0002]

2. Description of the Related Art With the recent development of information technology, the amount of information exchanged at distant places increases, and in order to cope with this, devices installed at remote locations are linked by an advanced communication network. There is a growing demand to improve the efficiency of business.

[0003] Under such circumstances, an LA that aims to improve work efficiency by connecting devices distributed in a business office or the like.
N has become common, and moreover, bridges and routers for connecting a plurality of LANs have appeared, and it has become possible to construct a larger-scale network. Devices that can be connected to a wide area network have appeared in bridges and routers, and it has become possible to interconnect remote LANs.

[0004] In a large-scale network, the effect of a failure is large. Therefore, for the purpose of improving reliability, a bridge or a router (hereinafter referred to as an LAN connection device) is arranged as shown in FIG. It has been proposed to take a configuration.

In FIG. 9, a plurality of terminals 10-1-1
10-2-1-n are connected to the LAN 20-1, a plurality of terminals 10-2-1 to 10-2-n are connected to the LAN 20-2, and the LAN 20-1 and the LAN 20-2 are connected to the LAN connection device 30-n. They are interconnected by 1 to 30-n. Here, one of the inter-LAN connecting devices 30-1 to 30-n, for example, the inter-LAN connecting device 30-1 becomes an active system and transfers packets between LANs.
The other LAN-to-LAN connecting devices 30-2 to 30-n become standby systems and wait as an alternative route in the event of a failure.

Then, the standby LAN connection device 30-
2 to 30-n intercept the packet transmitted by the transmission source terminal, intercept the packet transmitted by the active LAN connection device 30-1 to the destination terminal, and compare the two packets. Then, it is determined whether there is a failure in the operation system.

For example, terminal 10-1-1 (transmission source terminal)
When transmitting a packet to the terminal 10-2-3 (destination terminal) from the source terminal 10-1-1, the source terminal 10-1-1 transmits the packet to the destination terminal 10-2.
-3 are not connected to the same LAN, so that the packet is transmitted to the active LAN connection device 30-1.

Further, a standby LAN connection device 30-2
30-n intercept packets transmitted from the source terminal 10-1-1. Active LAN connection device 30-
1 investigates the destination address in the packet,
-2 is transmitted. At the same time, the standby LAN inter-connectors 30-2 to 30-n
-1 to intercept packets transmitted.

Then, the standby LAN connection device 30-
2 to 30-n are LAN 20-1 and LAN 20-2.
Are compared, and if they match, it is determined that the active LAN-to-LAN connecting apparatus 30-1 has normally operated.

[0010] Further, in order to connect remotely arranged LANs to each other, it has been proposed to arrange them as shown in FIG. 10 to take a redundant configuration.

In FIG. 10, a plurality of terminals 10-1-
1 to 10-1-n are connected to the LAN 20-1, a plurality of terminals 10-2-1 to 10-2-n are connected to the LAN 20-2, and the LAN 20-1 and the LAN 20-2 are connected to the LAN connection device 30. -1-1 to 30-1-n and the LAN connection devices 30-2-1 to 30-2-n are interconnected via the wide area network 40.

That is, in the configuration of FIG.
The LAN 20 is a pair of the N connection devices 30-1-1 to 30-1-n and the LAN connection devices 30-2-1 to 30-2-n.
-1 and the LAN 20-2.

Here, a plurality of inter-LAN connecting devices 30-1
-1 to 30-1-n and the LAN connection device 30-2-1
One of the pairs 30-2-n, for example, a pair of the inter-LAN connecting device 30-1-1 and the inter-LAN connecting device 30-2-1 becomes an active system and transfers packets between LANs, and the other pair includes That is, the LAN connection devices 30-1-2 to 30-
1-n and LAN connection devices 30-2-2 to 30-2-n
Is a standby system and stands by as an alternative route in case of failure.

The standby LAN connection device, ie, L
The AN connection devices 30-1-2 to 30-1-n intercept a packet transmitted by a source terminal, for example, the terminal 10-1-1, and intercept this packet as a standby LAN connection device as a pair. 30-2-2 to 30-2-n.

The standby LAN connection devices 30-2-2 to 30-2-n, which are a pair, are connected to the active LAN.
The connection device 30-2-1 is a destination terminal, for example, the terminal 10
-2-3. Intercept packets to be transmitted. Then, by comparing the transferred packet with the intercepted packet, the operating LAN connection devices 30-1-1 and L-
It is determined whether there is a failure in the AN connection device 30-2-1.

That is, when transmitting a packet from the source terminal 10-1-1 to the destination terminal 10-2-3, the source terminal 10-1-1 has the same L as the destination terminal 10-2-3.
Since it is not connected to the AN, the packet is transmitted to the active LAN connection device 30-1-1.

Standby LAN connection device 30-1-2
30-1-n intercepts a packet transmitted from the transmission source terminal 10-1-1 and transmits the intercepted packet to the wide area network 4.
0, a standby LAN connection device 30-
2-2 to 30-2-n.

An operation-system LAN connection device 30-1
-1 investigates the destination address in the packet, transmits the packet to the operating LAN connection device 30-2-1 that is a pair, and transmits the packet to the operating LAN connection device 30 that is the pair.
-2-1 transmits this packet to the LAN 20-2.

At the same time, the standby LAN connection device 30-
2-2 to 30-2-n are operating LAN connection devices 3
Intercept packets transmitted from 0-2-1.

Then, the standby LAN connection device 30-
2-2 to 30-2-n are LAN 20-1 and LAN
The packets intercepted from 20-2 are compared, and if they match, it is determined that the active LAN connection devices 30-1-1 and 30-2-1 operate normally.

However, according to the above configuration, although a failure of the active LAN connection device in pairs connected oppositely in the wide area network 40 can be detected, it is difficult to specify the individual failed LAN connection device. Was.

[0022]

As described above, a plurality of LAs are required.
In a conventional communication system having a redundant configuration by connecting N, even if a failure of the active LAN connection device can be detected for each pair connected in opposition, it is not possible to specify the individual failed LAN connection device. There was a problem that it was difficult.

Accordingly, the present invention provides an individual
It is an object of the present invention to provide a communication system having a highly reliable redundant configuration that enables identification of an N-to-N connection device.

[0024]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of LAN connecting devices for connecting one or a plurality of LANs are connected to each other via an ATM network, and are connected to the same device. One of a plurality of inter-LAN connecting devices connected to one LAN is used as an active system to perform packet communication connection between terminals connected to the LAN, and the other inter-LAN connecting device is used as a standby system. In the system, the active LAN connection device includes a transfer unit configured to transfer a packet transmitted from a source terminal to the standby LAN connection device via the ATM network.
The interworking device compares a packet received from a LAN connecting the source terminal with a packet transferred through the ATM network, and based on the comparison result, the active LAN.
Abnormality detecting means for detecting an abnormality of the interconnection device.

According to a second aspect of the present invention, in the first aspect of the present invention, the transfer means stores a packet received by the packet receiving means for receiving a packet transmitted from the LAN. First storage means, first path control means for selecting a route to be transmitted to the LAN from a destination address of the packet stored in the first storage means, and packet stored in the first storage means Cell transmission means for decomposing the data into fixed-length ATM cells and transmitting the data to the ATM network according to the path determined by the first path control means.
Cell receiving means for receiving ATM cells from the ATM network; second storing means for assembling and storing the ATM cells received by the cell receiving means into packets; and destination of the packets stored in the second storing means. L from the address
Second path control means for selecting a path to be transmitted to the AN;
The packet stored in the second storage means is transferred to the LAN according to the path determined by the second path control means.
Packet transmitting means for transmitting to a destination terminal connected to
A comparing unit that compares the packet stored in the first storage unit with the packet stored in the second storage unit.

According to a third aspect of the present invention, in the first aspect of the present invention, the transfer means includes a LAN for connecting a destination terminal.
LAN connection devices connected to the network and n standby LANs
A one-to-n multicast path is formed with the interconnection device, and the packet is transferred using the multicast path.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the standby LAN connection device is connected to an active LAN connected to the same LAN as the standby LAN connection device. When detecting an abnormality in the connection apparatus, the apparatus further comprises abnormality notification means for notifying at least the active LAN connection apparatus of the abnormality detection.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the operating system LAN is provided by the abnormality notifying means.
When the abnormality detection is notified to the inter-connecting device, the standby LAN inter-connecting device that has notified the abnormality detection is switched to the active system, and the active inter-LAN connecting device is switched to the standby system. It is characterized by further comprising a system switching means for switching to.

According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the abnormality notification means transmits the operating LAN.
When the abnormality detection is notified to the interconnecting device, a system switching unit that switches the standby LAN interconnecting device that has notified the abnormality detection to an active system, and receives the abnormality detection notification. And disconnecting means for separating the inter-LAN connecting device from another inter-LAN connecting device.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the inter-LAN connecting device separated from the other inter-LAN connecting device by the disconnecting means is switched to the active system by the system switching means. And a return unit for returning as a standby LAN connection device by adding a packet transfer path from the LAN connection device.

[0031]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a communication system having a redundant connection configuration according to the first embodiment of the present invention. In FIG. 1, portions having the same functions as those of the conventional configuration shown in FIGS. 9 and 10 are denoted by the same reference numerals as those used in FIGS. 9 and 10 for convenience of description.

In the communication system of the first embodiment shown in FIG. 1, the LAN connection devices 30-1-1 and 30-1-2 connected to the LAN 20-1 and the LAN connection connected to the LAN 20-2. The devices 30-2-1 and 30-2-2 are connected via the ATM network 50 for redundant connection.

That is, in FIG. 1, a plurality of terminals 10
-1-1 to 10-1-n are connected to, for example, a bus type LAN 20-1 composed of Ethernet, and the plurality of terminals 10-2-1 to 10-2-n are similarly composed of Ethernet. It is connected to the bus type LAN 20-2.

The LAN 20-1 is connected to LAN-to-LAN connecting devices 30-1-1 and 30-1-2. The LAN-to-LAN connecting devices 30-1-1 and 30-1-2 are A
Connected to TM network 50.

The LAN 20-2 is connected to LAN-to-LAN connecting devices 30-2-1 and 30-2-2. The LAN-to-LAN connecting devices 30-2-1 and 30-2-2 are A
Connected to TM network 50.

Here, the LAN connection devices 30-1-1,
30-1-2 and the LAN connection devices 30-2-1 and 3
0-2-2 forms a redundant connection.

That is, for example, the LAN connection device 30
-1-1 and the LAN connection device 30-2-1 are operated as the active system, and the LAN connection device 30-1-2 and the LAN
By operating the inter-connecting device 30-2-2 as a standby system, a redundant connection between the LAN 20-1 and the LAN 20-2 is realized.

Here, the active LAN connection device 30-
1-1, an active LAN connection device 30-2-1 and a standby system LAN connection device 30-1 via the ATM network 50;
-2, a one-to-three multicast path 50-1 is established with the standby LAN connection device 30-2-2.

The active LAN connection device 30-2
-1 is a working LAN connection device 30-1-1 and a standby LAN connection device 30-1-1 via the ATM network 50.
2. 1 between standby LAN connection device 30-2-2
A multicast path 50-2 of three pairs is established.

According to such a configuration, the working LAN
The detection of a failure that has occurred in the inter-connecting devices 30-1-1 and 30-2-1 is performed by the standby inter-LAN connecting devices 30-1-2 and 30-.
A communication system having a redundant connection configuration that can be individually detected in 2-2 can be constructed.

FIG. 2 is a block diagram of the LAN connection device 3 shown in FIG.
0-1-1, 30-2-1 and LAN connection device 30
1 shows the detailed configuration of the LAN connection device 30.

In FIG. 2, the LAN connection device 30
Means LAN port reception processing unit 301, LAN to ATM
Buffer 302, ATM transmission / reception processing unit 303, LAN
to ATM path control section 304, ATM port reception processing section 305, ATM to LAN buffer 306, LAN transmission / reception processing section 307, ATM to LAN path control section 30
8, a comparison processing unit 309 and a monitoring processing unit 310.

Here, the LAN to ATM buffer 302
Stores the packet received by the LAN port reception processing unit 301 and stores the packet in the ATM port reception processing unit 3
It has a plurality of buffers for storing control information to be transmitted to the ATM network 50 via the network 05. FIG. 3 shows the structure of the LANto ATM buffer 302.

As shown in FIG. 3, the LAN to ATM buffer 302 has a plurality of, for example, n buffers for storing, for example, n packets, each buffer having a control information section 302-1 for storing control information, It has a packet storage unit 302-2 for storing the converted packet.

The control information section 302-1 indicates the processing status of each buffer as control information. 1) Reception completion flag 302-3 2) Routing control request flag 302-4 3) Routing control completion flag 302-5 4 5) Transmission request flag 302-6 5) Transmission completion flag 302-7 6) Comparison request flag 302-8 7) Comparison completion flag 302-9 8) Holding time counter 302-10 9) Path information section 302-11 is stored. .

At the initial stage, all the flags 302-3 to 302-9 stored in the control information section 302-1 are turned off, and the holding time counter 302-10 is reset to "0".

The reception completion flag 302-3 is set to ON when the packet reception in the LAN port reception processing unit 301 is completed, the necessary processing in the LAN port reception processing unit 301 ends, and this buffer is returned to the empty buffer pool. And reset off.

The route control request flag 302-4 is set to ON when the LAN port reception processing unit 301 completes packet reception during the active system operation, and the necessary processing in the LAN port reception processing unit 301 ends. Is reset off when is returned to the free buffer pool.

The route control completion flag 302-5 is
Set to ON when the path control in the to-ATM path control unit 304 is completed, and the LAN-to-ATM path control unit 30
When the process in 4 is completed and this buffer is returned to the free buffer pool, it is reset to off.

Similarly, the transmission request flag 302-6 is set to L
It is set to ON when the route control in the ANtoATM path control unit 304 is completed, and is reset to OFF when the processing in the LANtoATM path control unit 304 ends and this buffer is returned to the free buffer pool.

The comparison request flag 302-8 is set to ON at the time of completion of packet reception in the LAN port reception processing unit 301 during standby operation, and necessary processing in the LAN port reception processing unit 301 ends, and this buffer becomes empty. Resets off when returned to the buffer pool.

The comparison completion flag 302-9 is set to ON when the comparison in the comparison processing unit 309 is completed, and is reset to OFF when the necessary processing in the comparison processing unit 309 is completed and this buffer is returned to the free buffer pool. You.

The holding time counter 302-10 is a LAN
When the packet reception in the port reception processing unit 301 is completed, the upper limit value of the holding time in the LAN to ATM buffer 302 is set.
It is periodically subtracted by 10. In normal operation, each process ends before the value of the holding time counter 302-10 becomes "0", and the value of the holding time counter 302-10 becomes "0" when this buffer is returned to the free buffer pool. Is reset to

For some reason, the holding time counter 3
If each process is not completed even when the value of 02-10 becomes “0”, this packet is detected by the monitoring processing unit 310.

The path information section 302-11 is set based on the result of the path control by the ATM path control section 304.

Now, the LAN port reception processing unit 301
It manages the availability of each buffer of the LANto ATM buffer 302, and pools the free buffer numbers in the LANto ATM buffer 302 in a free buffer pool.

The LAN port reception processing unit 301
When a packet is received, an empty buffer is reserved in the empty buffer pool by deleting the selected buffer from the pool, and storage of the received packet in the reserved buffer is started.

When all the received packets are stored in the buffer and the reception processing is completed, the LAN port reception processing unit 301 sets the reception completion flag 302-3 to ON in this buffer, and sets the route request flag 302-4 and the comparison request. By manipulating the request flag 302-8, the buffer number of this buffer is notified to the LAN to ATM path control unit 304 and the comparison processing unit 309.

Here, during the operation of the active system, at the end of the packet receiving process, the route request flag 302-4 is set to ON, the comparison request flag 302-8 is reset to OFF, and the LAN to ATM route control unit 304 When the standby system is in operation, the comparison request flag 302-8 is set to ON, and the route request flag 302-
4 is turned off to notify the comparison processing unit 309.

The LAN to ATM path control unit 304
The route request flag 302-4 of the buffer of the buffer number notified from the AN port reception processing unit 301 is checked to confirm that the route request flag 302-4 is set to ON, and the following route control process is performed. .

That is, the LAN to ATM path control unit 3
04 checks the destination address in the received packet, stores the path information corresponding to the route to the destination in the path information section 302-11, sets the path control completion flag 302-5 to ON, and sets the transmission request flag 302- 6 is set to ON, and the buffer number of this buffer is set to the ATM transmission / reception processing unit 303.
Notify to

The LAN to ATM path control unit 304
If the route control process in step 3 fails, the transmission request flag 302-6 remains off, and the ATM transmission / reception processing unit 303 is not notified of the buffer number.

The ATM transmission and reception processing unit 303
The transmission request flag 302-6 of the buffer of the buffer number notified from the oATM path control unit 304 is checked to confirm that the transmission request flag 302-6 is set to ON, and the following transmission operation is performed.

That is, the ATM transmission / reception processing unit 303
Decomposes the received packet into cells, and transmits the cells to the path of the ATM network 50 designated by the path information section 302-11.

When the transmission of the cell to the ATM network 50 is completed, the transmission completion flag 302-7 of the buffer is set to ON and the buffer number is notified to the monitoring processing unit 310.

If the transmission processing in the ATM transmission / reception processing unit 303 fails, the transmission completion flag 302-
7 is kept off, and the buffer number of this buffer is notified to the monitoring processing unit 310.

The comparison processing unit 309 is provided with a comparison request flag 302 notified from the LAN port reception processing unit 301.
-8 is checked to confirm that the comparison request flag 302-8 is set to ON, and the following comparison operation is performed.

That is, the comparison processing unit 309 determines that a packet matching the packet stored in the buffer
When the matching packet is detected by searching from the LAN buffer 306, the LAN to ATM buffer 302 and the ATM
The comparison completion flag 302-9 of the buffer of the corresponding packet with the toLAN buffer 306 is set to ON,
The monitoring unit 310 is notified of the buffer number.

If no matching packet is detected, the process is terminated with the comparison completion flag 302-9 of the buffer kept off.

When the monitoring processing unit 310 confirms that all the flags 302-3 to 302-9 of the buffer of the buffer number notified from the ATM port transmission processing unit 303 are set to ON, the monitoring processing unit 310 Information 302
-1 are all reset, and the buffer number is notified to the LAN port reception processing unit 301. If there is an off flag among the flags 302-3 to 302-9 of the buffer, the process is terminated with this flag kept as it is.

When it is confirmed that all the flags 302-3 to 302-9 of the buffer number notified from the comparison processing unit 309 are set to ON, all the control information 302-1 of the buffer is reset. Then, the buffer number of the buffer is notified to the LAN port reception processing unit 301. Here, each flag 302-3 to
If there is an OFF flag in 302-9, this flag is left as it is, and the processing is terminated.

Further, the monitoring processing unit 310 periodically
Holding time counter 302-10 during processing of NtoATM buffer 302 (buffer other than free buffer pool)
Is subtracted, and the status of each flag of the buffer in which the count value of the holding time counter 302-10 has become "0" is examined. Here, when a buffer in which the path completion flag 302-5 remains OFF is found, the holding time counter 302-10 of the buffer is added.

When a buffer in which the transmission completion flag 302-7 remains off is found, a transmission error counter (not shown) of the buffer is added. If a buffer in which the comparison completion flag 302-9 remains off is found, a comparison error counter (not shown) of the buffer is added. A threshold value is provided for each of the transmission error counter and the comparison error counter, and an error is detected when the count values of the transmission error counter and the comparison error counter exceed the threshold values within a predetermined time. Here, the transmission error counter and the comparison error counter are periodically reset.

After the error count processing of the transmission error counter and the comparison error counter, all the control information 302-1 of the buffer is reset, and the buffer number of the buffer is notified to the LAN port reception processing unit 301.

The LAN port reception processing unit 301 returns the buffer number notified from the monitoring processing unit 310 to the buffer empty pool.

The ATM to LAN buffer 306 has an AT
The packet received by the M reception processing unit 305 is stored and stored in the LA
It has a plurality of buffers for transmitting to the N-port transmission processing unit 307.

FIG. 4 shows the ATM to LAN buffer 3
12 shows the structure of No. 06.

In FIG. 4, the ATM to LAN buffer 306 stores a plurality of, for example, n packets.
Each buffer has a control information unit 306-1 for storing control information and a packet storage unit 306-2 for storing received packets.

The control information section 306-1 indicates the processing status of each buffer as control information. 1) Reception completion flag 306-3 2) Route control request flag 306-4 3) Route control completion flag 306-54 ) Transmission request flag 306-6 5) Transmission completion flag 306-7 6) Comparison request flag 306-8 7) Comparison completion flag 306-9 8) Holding time counter 306-10 9) Port information section 306-11 is stored. .

At the initial stage, all the flags 306-3 to 306-9 stored in the control information section 306-1 are turned off, and the holding time counter 306-10 is reset to "0".

The reception completion flag 306-3 is set to ON when the packet reception in the ATM port reception processing unit 305 is completed, the necessary processing in the ATM port reception processing unit 305 ends, and this buffer is returned to the empty buffer pool. And reset off.

The route control request flag 306-4 is set to ON when the packet reception by the ATM port reception processing unit 305 is completed during the active operation, and the necessary processing in the ATM port reception processing unit 305 is completed. Is reset off when is returned to the free buffer pool.

The route control completion flag 306-5 is an ATM
It is set to ON when the path control in the toLAN path control unit 308 is completed, and the ATM to LAN path control unit 30
When the process in 8 is completed and this buffer is returned to the free buffer pool, it is reset to off.

Similarly, the transmission request flag 306-6 indicates that A
It is set to ON when the path control in the TMtoLAN path control unit 308 is completed, and is reset to OFF when the processing in the ATMtoLAN path control unit 308 ends and this buffer is returned to the free buffer pool.

The comparison request flag 306-8 is set to ON when the packet reception in the ATM port reception processing unit 305 is completed during the standby operation, and the necessary processing in the ATM port reception processing unit 305 is completed. Resets off when returned to the buffer pool.

The comparison completion flag 306-9 is set to ON when the comparison in the comparison processing unit 309 is completed, and is reset to OFF when the necessary processing in the comparison processing unit 309 is completed and this buffer is returned to the free buffer pool. You.

The holding time counter 306-10 has an ATM
When the packet reception in the port reception processing unit 305 is completed, the upper limit value of the holding time in the ATM to LAN buffer 306 is set.
It is periodically subtracted by 10. In a normal operation, each process ends before the value of the holding time counter 306-10 becomes "0", and the value of the holding time counter 306-10 becomes "0" when this buffer is returned to the free buffer pool. Is reset to

For some reason, the holding time counter 3
If each process is not completed even when the value of 06-10 becomes “0”, this packet is detected by the monitoring processing unit 310.

The port information section 306-11 has the ATMto
This is set by the LAN path control unit 308.

Now, the ATM port reception processing unit 305
The buffer management of each buffer of the ATMtoLAN buffer 306 is performed, and the free buffer numbers in the ATMtoLAN buffer 306 are pooled in a free buffer pool.

The ATM port reception processing unit 305
When a cell (including the beginning of a packet) is received, a free buffer is reserved in the free buffer pool by deleting the selected buffer from the pool, and storage of the received cell in the reserved buffer is started.

When all the received cells are stored in the buffer and the reception processing is completed, the ATM port reception processing unit 305 sets the reception completion flag 306-3 to ON in this buffer, and sets the path request flag 306-4 and the comparison result. By manipulating the request flag 306-8, the buffer number of this buffer is notified to the ATM to LAN path control unit 308 and the comparison processing unit 309.

Here, during the operation of the active system, at the end of the packet reception processing, the route request flag 306-4 is set to ON, the comparison request flag 306-8 is reset to OFF, and the packet is transmitted to the ATM to LAN route control unit 308. The notification is performed, and during the standby system operation, the comparison request flag 306-8 is set to ON, and the route request flag 306-
4 is turned off to notify the comparison processing unit 309.

The ATM to LAN path control unit 308
The route request flag 306-4 of the buffer of the buffer number notified from the TM port reception processing unit 305 is checked to confirm that the route request flag 306-4 is set to ON, and the following route control process is performed. .

That is, the ATM to LAN path control unit 3
08 checks the destination address in the received packet, and outputs the path information corresponding to the route to the destination to the port information unit 306-11.
And the path control completion flag 306-5 is set to ON, the transmission request flag 306-6 is set to ON, and the buffer number of this buffer is set to the LAN transmission / reception processing unit 30.
Notify 7.

The ATM to LAN path control unit 308
If the path control process in step 2 fails, the transmission request flag 306-6 is kept off, and the LAN transmission / reception processing unit 307 is not notified of the buffer number.

[0098] The LAN transmission / reception processing unit 307 outputs the ATM t
The transmission request flag 306-6 of the buffer of the buffer number notified from the oLAN path control unit 308 is checked to confirm that the transmission request flag 306-6 is set to ON, and the following transmission operation is performed.

That is, the packet is transmitted to the port specified by the port information section 306-11.

When the transmission of the packet to the port specified by the port information section 306-11 is completed, the transmission completion flag 306-7 of the buffer is set to ON, and this buffer number is notified to the monitoring processing section 310.

If the transmission processing in the LAN transmission / reception processing unit 307 fails, the transmission completion flag 306-
7 is kept off, and the buffer number of this buffer is notified to the monitoring processing unit 310.

The comparison processing unit 309 is provided with a comparison request flag 306 notified from the ATM port reception processing unit 305.
-8 is checked to confirm that the comparison request flag 306-8 is set to ON, and the following comparison operation is performed.

That is, the comparison processing unit 309 converts a packet matching the packet stored in the buffer into a LANto packet.
When a search is made from the ATM buffer 302 and a matching packet is detected, the ATM to LAN buffer 306 and the LAN
The comparison completion flag 306-9 of the buffer of the corresponding packet with the toATM buffer 302 is set to ON,
The monitoring unit 310 is notified of the buffer number.

If no matching packet is detected, the process is terminated with the comparison completion flag 306-9 of the buffer kept off.

When the monitoring processing unit 310 confirms that all the flags 306-3 to 306-9 of the buffer of the buffer number notified from the LAN port transmission processing unit 307 have been set to ON, the monitoring processing unit 310 Information 306
-1 are all reset, and the buffer number is notified to the ATM port reception processing unit 301. Here, if there is an off flag among the flags 306-3 to 306-9 of the buffer, this flag is left as it is, and the process ends.

When it is confirmed that all the flags 306-3 to 306-9 of the buffer number notified from the comparison processing unit 309 are set to ON, the control information 306-1 of the buffer is reset. Then, the buffer number of the buffer is notified to the ATM port reception processing unit 305. Here, each flag 306-3 to
If there is an off flag in 306-9, this flag is left as it is, and the process ends.

Further, the monitoring processing unit 310 periodically executes the AT
Holding time counter 306-10 during processing of MtoLAN buffer 306 (buffer other than free buffer pool)
Is subtracted, and the status of each flag of the buffer in which the count value of the holding time counter 306-10 has become "0" is examined. Here, when a buffer in which the path completion flag 306-5 remains OFF is found, the holding time counter 306-10 of the buffer is added.

If a buffer in which the transmission completion flag 306-7 remains off is found, a transmission error counter (not shown) of the buffer is added. If a buffer in which the comparison completion flag 306-9 remains off is found, a comparison error counter (not shown) of the buffer is added. A threshold value is provided for each of the transmission error counter and the comparison error counter, and an error is detected when the count values of the transmission error counter and the comparison error counter exceed the threshold values within a predetermined time. Here, the transmission error counter and the comparison error counter are periodically reset.

After the error count processing of the transmission error counter and the comparison error counter, all the control information 306-1 of the buffer is reset, and the buffer number of the buffer is notified to the ATM port reception processing unit 305.

The ATM port reception processing unit 305 returns the buffer number notified from the monitoring processing unit 310 to the buffer empty pool.

As described above, in the communication system of this embodiment, the standby LAN connecting device 30-1-2,
30-2-2 is an active LAN connection device 30-1-1
By monitoring 1, 30-2-1, a failure in the LAN-to-LAN connecting device can be detected.

FIG. 5 shows a communication system having a redundant connection configuration according to the second embodiment of the present invention.

The communication system according to the second embodiment shown in FIG. 5 is different from the communication system according to the first embodiment shown in FIG.
-2-2 to the active LAN connection device 30-1-1,
30-2-1 is configured by adding failure notification control paths 50-3 and 50-4 for performing failure notification.

In the communication system of this embodiment,
For example, when the standby LAN connection device 30-1-2 detects a failure of the active LAN connection device 30-1-1, the standby LAN connection device 30-1-2 transmits the failure notification A failure notification is sent to the active LAN connecting device 30-1-1 via the control path 50-3 of the active system, and the active LA
The inter-N connection device 30-1-1 switches to the standby system, and the inter-LAN connection device 30-1-2 in the standby system switches to the active system instead of the inter-LAN connection device 30-1-1.

FIG. 6 shows the LAN connection device 3 shown in FIG.
0-1-1, 30-2-1 and LAN connection device 30
1 illustrates the detailed configuration of each of the LAN-connection devices 300.

The LAN connecting device 300 shown in FIG. 6 is different from the LAN connecting device 30 shown in FIG. 2 in that the active LAN connecting device 30-1-1 and the standby LAN connecting device 30-1-1.
Control information transmitting unit 3 for exchanging control information with the control information
11 and a control information receiving unit 312 are added.

In the configuration shown in FIG. 6, for example, the monitoring processor 310 of the standby LAN connection device 30-1-2 is used.
When the failure of the active LAN connection device 30-1-1 is detected, the control information transmitting unit 311 of the standby LAN connection device 30-1-2 sends the active LAN connection device 30-1-2 to the standby LAN connection device 30-1-2.
At -1-1, a failure detection notification is performed via the failure notification control path 50-3.

The notification of the failure detection is received by the control information receiving unit 312 of the working LAN connection device 30-1-1, whereby the working LAN connection device 30-1-1 is received.
Reference numeral 1 denotes a switch to the standby system, and that the switch to the standby system indicates that the path 50 on the ATM network 50 used for normal packet transfer to the LAN-to-LAN connecting device 30-1-2.
-1 to the LAN connection device 30-1-2.

As a result, the LAN connection device 30-1-
2 is switched to the active system and the LAN connection device 30-1-
Take over the operation in place of 1.

As described above, in the communication system according to this embodiment, the standby LAN connection device 30-1-
2, 30-2-2 are active LAN inter-connectors 30-1.
-1 and 30-2-1 are monitored, and the failure of the active LAN connection devices 30-1-1 and 30-2-1 is monitored for the standby LAN.
When it is detected by the LAN connection devices 30-1-2 and 30-2-2, the standby LAN connection devices 30-1-2 and 30-
2-2 via the fault notification control paths 50-3 and 50-4 to the active LAN connection devices 30-1-1 and 30-31.
By notifying the failure detection to -2-1, the current system L
It is possible to switch between the AN connection devices 30-1-1 and 30-2-1 and the standby LAN connection devices 30-1-2 and 30-2-2.

In the communication system having the redundant connection configuration according to the third embodiment of the present invention, for example, the standby LAN inter-connector 30-1-2 is replaced by the active LAN inter-connector 30-1-1. 1 is detected, the LAN connection device 30-1-2 is switched from the active LAN connection device 30-1-2 to the active LAN connection device 30-1-2.
-2-1 notifies a disconnection request from the inter-LAN connecting device 30-1-1, and further notifies the inter-LAN connecting device 30-1-1.
2 notifies the working LAN connection device 30-2-1 of connection to the LAN connection device 30-1-2. Then, after the LAN connecting device 30-2-1 is disconnected from the LAN connecting device 30-1-1 and connected to the LAN connecting device 30-1-2, the active LAN connecting device 30-1 is connected. -1 is switched to the standby system, and the standby LAN
By switching the connection device 30-1-2 to the active system,
Switches between the active system and the standby system.

That is, in the communication system of the third embodiment, for example, the standby LAN connection device 30-
When detecting the failure of the active LAN connection device 30-1-1 in 1-2, the control information transmitting unit 311 of the LAN connection device 30-1-2 shown in FIG. A notification of a disconnection request from the inter-LAN connecting device 30-1-1 is sent to the inter-LAN connecting device 30-2-1 via the path 50-3.

This notification is sent to the LAN connection device 30-2-1.
6 is received by the control information receiving unit 312 shown in FIG. 6, whereby the inter-LAN connecting device 30-2-1 is disconnected from the inter-LAN connecting device 30-1-1.

Next, the control information transmitting unit 311 of the inter-LAN connecting device 30-1-2 sends the inter-LAN connecting device 30-2-1 to the inter-LAN connecting device 30-2-1 via the control path 50-3. Notification to connect to 1-2 is made. This notification is L
The control information receiving unit 312 of the inter-AN connection device 30-2-1 receives the control information.
Is disconnected from the LAN connection device 30-1-1.

Thereafter, the active LAN connection device 30-
1-1 is switched to the standby system, and the LAN connection device 30-1-2 in the standby system is switched to the active system.

FIG. 7 shows a connection configuration after switching between the active system and the standby system in the communication system according to the third embodiment.

In FIG. 7, the LAN connection device 30-2
-1 is separated from the inter-LAN connecting device 30-1-1, and is connected to the inter-LAN connecting device 30-1-2 and the paths 50-5, 5-5.
0-6, and the LAN connection device 30-1
-2 becomes the active system, and the inter-LAN connecting device 30-1-2 takes over its operation in place of the inter-LAN connecting device 30-1-1.

Here, the inter-LAN connecting device 30-1-2 from the inter-LAN connecting device 30-2-1 via the ATM network 50.
The transfer of the packet to the LAN connecting device 30-2-2 is performed via the path 50-5, and the LAN connecting device 30-2 is connected to the LAN connecting device 30-1-2 via the ATM network 50. -1 and LAN connection device 30-2-2
Is transferred via the path 50-6.

Also, the standby LAN connection device 30-2
-2 and the active LAN connection device 30-1-2 and L
The control path 50- is connected to the AN connection device 30-2-1.
7 is connected.

In the communication system according to the third embodiment, when the function of the inter-LAN connecting device 30-1-1 disconnected by the failure detection is restored by a failure repair or the like, the communication system is not connected to the communication system. It is requested to return to the standby LAN connection device.

That is, the LAN connection device 30-1-1
From the LAN connection device 30-
1-1 joins the broadcast path of the packet between the active LAN connection device 30-1-2 and the LAN connection device 30-2-1. Also, the LAN connection device 30-1-
1 is an active LAN connection device 30-1-2 and L
The control information path is connected to the AN connection device 30-2-1.

In this way, the LAN connection device 30-
1-2 and the LAN-to-LAN connecting device 30-2-1,
The communication system returns to the communication system in which the LAN connection device 30-1-1 and the LAN connection device 30-2-2 are set as standby systems.

FIG. 8 shows a communication system having a redundant connection configuration according to a fourth embodiment of the present invention.

In the communication system according to the fourth embodiment, for example, the inter-LAN connecting device 30-1-1 and the inter-LAN connecting device 30-2-1 are set to the active system, and the inter-LAN connecting device 30-1-1 is used. 2 and LAN connection device 30-2
-2 is configured as a standby system.

The active LAN connecting device 30-1-1 and the LAN connecting device 30-2-1 and the standby LAN connecting device 30-1-2 and the LAN connecting device 30-2
-2, the active LAN connection device 30-1-1
To the active LAN connecting device 30-2-1, the standby LAN connecting device 30-1-2, and the LAN connecting device 3
A packet transfer path 50-10 for transmitting a packet to 0-2-2, connection between the active LAN connection device 30-2-1 to the active LAN connection device 30-1-1, and standby LAN connection. Device 30-1-2, LAN connection device 30
-Path 5 for packet transfer transmitting packet to -2-2
0-11 are connected, and the standby LAN connection device 30-1-2 is connected to the standby LAN connection device 30-2-2.
2 and working LAN connection device 30-1-1, LA
A control path 50-12 for transmitting control information to the N-to-N connection device 30-2-1; a standby LAN-to-LAN connection device 30-2-2;
Control path 50-13 for transmitting control information from the LAN connection device 30-1-2 to the standby system, to the active LAN connection device 30-1-1, and to the LAN connection device 30-2-1.
Is connected.

Here, the packet transfer path 50-1
0, 50-11, transfer of packets between LANs is performed, and in the control paths 50-12, 50-13, the LAN connection devices 30-1-1, 30-2-1, 30-1-2, 3
Communication in each state of 0-2-2 is performed.

According to such a configuration, the working LAN
Connection device 30-1-1, 30-2-1 and standby LA
When switching between the N-to-N connection devices 30-1-2 and 30-2-2, it is not necessary to switch paths, and the switching of the redundant connection configuration of the LAN-to-LAN connection device with reduced path change processing can be realized.

[0138]

As described above, according to the present invention,
The following effects can be obtained.

1) It is possible to individually detect the failure of the active LAN connection device without increasing the processing of the active LAN connection device.

2) Since the switching between the active LAN connection device and the standby LAN connection device can be performed for each LAN connection device, the probability of returning to the normal operation by this switching increases.

3) Disconnecting the inter-LAN connecting device that cannot be switched from the active system to the standby system, and disconnecting the separated LAN
When the inter-connection device recovers, it can be recovered.

4) The participation of the inter-LAN connecting device as a standby system after the repair can be performed without stopping the operation of the system.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of a communication system having a redundant connection configuration according to the present invention.

FIG. 2 is a block diagram showing a detailed configuration of the LAN connection device shown in FIG. 1;

FIG. 3 is a view showing the structure of a LANto ATM buffer shown in FIG. 1;

FIG. 4 is a view showing the structure of the ATMtoLAN buffer shown in FIG. 1;

FIG. 5 is a system configuration diagram showing a second embodiment of a communication system having a redundant connection configuration according to the present invention.

FIG. 6 is a block diagram showing a detailed configuration of the inter-LAN connecting device shown in FIG. 5;

FIG. 7 is a diagram showing a connection configuration after switching between a working system and a standby system in a communication system according to a third embodiment of the communication system having a redundant connection configuration according to the present invention;

FIG. 8 is a system configuration diagram showing a fourth embodiment of a communication system having a redundant connection configuration according to the present invention.

FIG. 9 is a system configuration diagram showing a conventional example of a communication system having a redundant connection configuration.

FIG. 10 is a system configuration diagram showing another conventional example of a communication system having a redundant connection configuration.

[Explanation of symbols]

10-1-1 to 10-1-n, 10-2-1 to 10-2
-N terminal 20-1, 20-2 LAN 30-1-1, 30-2-1, 30-1-2, 30-2
-2 LAN connection device 50 ATM network 301 LAN port reception processing unit 303 LANto ATM buffer 303 ATM transmission / reception processing unit 304 LANtoATM path control unit 305 ATM port reception processing unit 306 ATMtoLAN buffer 307 LAN transmission / reception processing unit 308 ATMtoLAN path control unit 309 Comparison processing unit 310 Monitoring processing unit 311 Control information transmission unit 312 Control information reception unit

Claims (7)

[Claims] 1. A plurality of inter-LAN connecting devices for connecting one or a plurality of LANs are connected to each other via an ATM network, and one of the plurality of inter-LAN connecting devices connected to the same LAN is in use. In a communication system in which a packet communication connection is performed between terminals connected to the LAN as a system and another LAN connection device is a standby system, the active LAN connection device is transmitted from a source terminal. Transfer means for transferring the received packet to the standby LAN connection device via the ATM network, wherein the standby LAN connection device receives the packet received from the LAN connecting the source terminal and the packet. Compare the packets transferred over the ATM network,
A communication system comprising: an abnormality detecting unit configured to detect an abnormality of the active LAN connection device based on the comparison result. 2. The packet transfer device according to claim 1, wherein the transfer unit includes: a packet receiving unit configured to receive the packet transmitted from the LAN; a first storage unit configured to store the packet received by the packet receiving unit; First path control means for selecting a path to be transmitted to the LAN from the destination address of the stored packet; and a fixed length A packet stored in the first storage means.
Cell transmission means for decomposing into TM cells and transmitting to the ATM network according to the path determined by the first path control means, wherein the abnormality detection means comprises a cell for receiving an ATM cell from the ATM network. Receiving means; second storing means for assembling and storing ATM cells received by the cell receiving means into packets; and selecting a route to be transmitted to the LAN from a destination address of the packets stored in the second storing means. A second route control unit that performs packet transfer stored in the second storage unit according to the route determined by the second route control unit.
A packet transmitting means for transmitting to a destination terminal connected to the first storage means, and a comparing means for comparing a packet stored in the first storage means with a packet stored in the second storage means. The communication system according to claim 1, wherein 3. The transfer means forms a one-to-n multicast path between an inter-LAN connecting device connected to a LAN connecting a destination terminal and n standby inter-LAN connecting devices. The communication system according to claim 1, wherein the transfer of the packet is performed using a multicast path. 4. The standby LAN connection device, when detecting an abnormality in an active LAN connection device connected to the same LAN as the standby LAN connection device,
2. The communication system according to claim 1, further comprising an abnormality notifying unit that notifies at least the active LAN connection device of the abnormality detection. 5. The operating system according to claim 1, wherein
When the abnormality detection is notified to the AN connection device, the standby system LA that has notified the abnormality detection.
The inter-N connection device is switched to the active system, and the active LAN
The communication system according to claim 4, further comprising system switching means for switching the interconnection device to a standby system. 6. The operating system according to claim 1, wherein
When the abnormality detection is notified to the AN connection device, the standby system LA that has notified the abnormality detection.
System switching means for switching the N-to-N connection device to the active system;
5. The communication system according to claim 4, further comprising a disconnecting unit that disconnects from the AN connection device. 7. A path for transferring a packet from the inter-LAN connecting device switched from the inter-LAN connecting device separated from another inter-LAN connecting device to the active system by the system switching device by the disconnecting means. 7. The communication system according to claim 6, further comprising a return unit for returning as a standby LAN connection device by means of.