JPH07162442A - Lan repeating device - Google Patents

Abstract

PURPOSE:To increase the capacity of a trunk line LAN by shortening the transfer time of data frames. CONSTITUTION:A network repeating device 104 takes an opposite party address from a data frame sent from an information processor 106 through a branch line LAN 101. Then a selecting means 40 selects one of trunk line LANs constituting a trunk line LAN group 103 according to the opposite party address. The selection in this case is made according to specific selection information, which is stored in a memory which inputs some bit arrays generated by properly dividing the opposite party address as an address. Then the selected trunk line LAN is connected to the branch line LAN 101 by a repeating means 402. A network repeating device 105 also has the same constitution. Further, data frames in a communication are stored in the network repeating device 104 and resent if a data error is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN relay device which connects a plurality of LANs and relays them with each other.

[0002]

2. Description of the Related Art Information processing apparatuses such as personal computers and workstations were initially used as a stand-alone type in which resources such as files were used and stored in each apparatus. However, in recent years, with the spread of information processing devices, these information processing devices have been connected to each other by data communication means in order to share resources such as files and printers among a plurality of information processing devices. ing.
A LAN (local / local
Area network) is widely used.

On the other hand, due to the recent progress in technological development, the processing performance and memory capacity of information processing devices have significantly increased. Therefore, the demand for improving the capacity of LAN is also increasing. Therefore, FDDI (Fiber Distributed Data)
A LAN having a data transfer capability of 100 Mbps class such as Interface) has also been developed. Where FDD
“I” is an item that enables a higher speed data communication by spatially expanding the LAN by using an optical fiber cable. In the early stage of the spread of such LAN,
Most of them were types that shared data and network resources within one department. However, since data can be shared among a plurality of departments to improve mutual work, a network relay device for interconnecting a plurality of existing LANs has also been developed.

Normally, a LAN within one department uses a 10 Mbps class LAN such as an Ethernet system or a token ring system as a branch line LAN. Here, the Ethernet method is a bus type CS using a coaxial cable.
It is a MA / CD (collision detection) type LAN. This is a method in which a plurality of devices transmit data once, and when data collision occurs, only the device with the higher priority is allowed to transmit. The token ring system is a system in which data called a token for controlling a transmission right is circulated in a ring network, and only a device that receives the token transmits the data. That is, in this method, when the device that has received the token has data to be transmitted, the token is used and is circulated to the next device, and the destination is specified and the data is transmitted. In this case, the device receiving the token in use cannot send data. On the other hand, when the device that has completed the data transmission receives the token again, it releases the token in use,
Circulate to the next device. This allows the device that received the next token to send data.

A plurality of branch line LANs of this type are provided. A high-speed LAN such as the above-mentioned FDDI having a communication capacity about 10 times that of the branch line LAN is used as the main line LAN connecting the plurality of branch line LANs. A network relay device such as a bridge is used to connect the branch LAN and the trunk LAN.

(1) First Conventional Example FIG. 2 shows a first configuration example of a conventional system in which a plurality of LANs are connected. In FIG. 2, the branch LANs 1 and 2 and the trunk LAN 3 are connected by network relay devices 4 and 5. Information processing devices 6 and 7 are connected to the branch LANs 1 and 2, respectively. Branch line LAN 1, 2
Is Ethernet and has a communication capability of, for example, 10 Mbps. The main line LAN3 is FDDI, for example, 1
It has a communication capability of 00 Mbps.

Next, in FIG. 2, an example of the operation when data is transferred from the information processing device 6 on the branch line LAN1 to the information processing device 7 on the branch line LAN2 will be described. First, in the information processing device 6, when a data transfer request to the information processing device 7 is generated, the information processing device 6 uses its own address (source address) and the address of the information processing device 7 (destination address) in the data. A data frame to which is added is generated and transmitted on the branch line LAN1. Then, the transmitted data frame is once received by the network relay device 4.

The network relay device 4 checks the destination address of the received data frame and checks the trunk LAN.
It is determined whether the data should be transferred to the 3rd party. In this case, since the address of the information processing device 7 is set as the destination address of the data frame, the network relay device 4
Transfers the data frame to the trunk LAN 3 side. Then, the same data frame relay operation is performed in the network relay device 5. As a result, the data frame is finally sent out onto the branch line LAN2. After that, the information processing device 7 receives the data frame.
As a result, the transmission of the data frame from the information processing device 6 to the information processing device 7 ends. FIG. 3 shows the above operation on the time axis.

FIG. 3 shows the state of the data frame in the network components such as the information processing device 6, the network relay devices 4, 5 and the information processing device 7 with respect to the time axis (horizontal axis). First, the information processing device 6
Starts transmitting a data frame addressed to the information processing device 7 at time 0. The transmission time (packet transfer time) of the data frame is T1. Therefore, the information processing device 6
At time T1, the transmission of the data frame ends.

On the other hand, the network relay device 4 has a time 0.
The reception of the data frame transmitted by the information processing device 6 is started after the propagation delay time Td from. In this case, the network relay device 4 first checks the destination address of the received data frame and determines whether or not it should be transferred to the trunk LAN 3 side based on the destination address. Main line LA
When determining that the data should be transferred to the N3 side, the network relay device 4 converts the received data frame into a format defined by the protocol of the trunk LAN 3. Then, it waits for the access right of the trunk LAN 3 to be obtained. This waiting time is Tw1. When the network relay device 4 obtains the access right (receives a free token in the case of FDDI), it transfers the data frame to the trunk LAN 3. The time at this time is T1 + Td1 + Tw1.

On the other hand, the network relay device 5 has a time T.
The reception of the data frame relayed by the network relay device 4 is started by 1 + Td1 + Tw1 + Td2. Here, Td2 is a propagation delay time from the network relay device 4 to the network relay device 5. The network relay device 5 has time T1 + Td1 + Tw1 + Td2 + T2.
Then, the reception of the data frame is completed. Where T2
Is the transmission time of the data frame on the trunk LAN 3. This time T2 is about 1/10 of the time T1. The network relay device 5 checks the destination address of the received data frame and checks the branch line LA.
It is determined whether or not the data should be transferred to the N2 side. Since the data frame is addressed to the information processing device 7, the network relay device 5 converts the data frame into a format defined by the protocol of the branch line LAN2. Then, the network relay device 5 waits for the acquisition of the access right of the branch line LAN 2 (in the case of Ethernet, the presence / absence of data transfer on the network is checked).

Assuming that the waiting time at this time is Tw2, the network relay device 5 obtains the access right of the branch line LAN2 at time T1 + Td1 + Tw1 + Td2 + T2 + Tw2. Then, the network relay device 5 starts to transfer the data frame to the branch line LAN2 side. The information processing device 7 starts receiving the data frame after the transmission delay time Td3 on the branch line LAN2. And finally, time T1 + Td1 + Tw1 + Td2 + T2 + Tw2 +
The reception of the data frame from the information processing device 6 ends at T1 + Td3. Here, the branch line LAN2 is a branch line LAN
Since the data transfer rate is the same as that of 1, the transfer rate of the data frame is T1.

As is clear from FIG. 3, when it is necessary to exchange data between the information processing devices 6 and 7 via the trunk LAN 3, the branch LANs 1 and 2 and the trunk LAN 3 are connected.
3 have different data transfer rates, and the format of the data frame defined by each protocol is different. Therefore, the data frames must be stored once in the network relay devices 4 and 5. Since data is exchanged after such data storage, the data frame transfer delay time becomes long even though a high-speed LAN is used as the trunk LAN 3. That is, the main line LA
Data frame transmission time T2 at N3 is branch line LAN1,
Although it is about one-tenth of the transmission time T1 in 2 above, the data frame transmission delay time is twice or more than T1. Therefore, the merit of the high-speed main line LAN 3 is not effectively used.

Further, the network relay devices 4, 5 of FIG.
When a data frame is received at one of the ports, the address comparison unit determines whether or not the data frame should be relayed inside the network relay device 4, 5.
FIG. 4 shows an internal configuration example of this address comparison unit. The address comparison unit 8 shown in FIG.
Are provided inside each of. The address comparison unit 8 includes a destination address register 9 and a processor 10. The destination address register 9 is L
It is a register that stores an address of a transfer destination of a data frame received by the AN interface.

The processor 10 stores the address stored in the destination address register 9 and the transfer address table 1
The process of comparing with the address stored in 1 is performed. The transfer address table 11 includes a transfer address area 12 and a non-transfer address area 13. Transfer address area 12
Is an area for storing an address transferred by the network relay device. The non-transfer address area 13 is an area for storing an address which is not transferred by the network relay device. In the initial state of the network relay device, the contents of the transfer address table 11 are cleared, and from that state, the source addresses of the data frames received by the plurality of LAN interfaces of the network relay device are sequentially transferred to the transfer address area 12 or the non-addressed area. It is stored in the transfer address area 13.

The operation of comparing destination addresses when a data frame is received by the LAN interface having the address comparison unit 8 during operation of the network relay device will be described below. First, the destination address of the received data frame is stored in the destination address register 9, and the execution of the address comparison operation is notified to the processor 10. Receiving the notification, the processor 10 reads the contents (first address) of the destination address register 9 of the received data frame into the internal register 14 of the processor 10.
After that, the addresses (second addresses) stored in the sequential transfer address table 11 are read and compared with the first addresses. If the first address matches the address stored in the transfer address area 12,
According to the information in the transfer address area, transfer to another LAN interface inside the network relay device,
Instruct the LAN interface control unit.

If the address does not match the address stored in the transfer address area 12, the address stored in the non-transfer address area 13 is continuously compared.
Then, when the address matches the address stored in the non-transfer address area 13, the received data frame is discarded. On the other hand, when it does not match the address stored in the non-transfer address area 13, the following processing is performed. As shown in FIG. 5, the network relay device 4
The other network relay devices 41 and 42 are also connected to the main network via the trunk LANs 31 and 32, respectively. As a result, when the first address does not match the address stored in the non-transfer address area 13, the first address is stored in the non-transfer address area 13 and the network relay devices 41, 42. The first address of the other LAN interface inside the device is set to the transfer address areas 51 and 53 of each transfer address table.
To store in. After that, the broadcast operation is performed so as to relay the received data frame to all of the other LAN interfaces described above.

(2) Second Conventional Example FIG. 6 is a block diagram of the second conventional example. As shown in FIG. 6, the configuration of the second conventional example is almost the same as the configuration of the first conventional example of FIG. 2, but the trunk line LAN 3 ′ has branch lines LAN 1, 2.
The difference is that it is Ethernet as well as. That is,
The branch lines LAN1 and LAN2 and the trunk line LAN3 'have the same data transfer rate and protocol. Further, the data frame relay method in the network relay devices 4 and 5 is different from the above-mentioned example.

In the second conventional example, by making the data transfer rates of the trunk LAN 3'and the branch LANs 1 and 2 the same, the transmission of the received data frame is started when the received data frame is accumulated halfway. It is possible. As a result, the storage delay time of the data frame in the network relay device is shortened and the data frame between a plurality of LANs is relayed. Such a relay system is called a cut-and-through system. FIG. 7 shows a data frame transmitting operation from the information processing device 6 to the information processing device 7 in the second conventional example.

As shown in FIG. 7, since the data transmission speeds of the branch lines LAN1 and LAN2 and the trunk line LAN3 'are the same, the data frame accumulation time in the network relay device for speed conversion becomes unnecessary. That is, the transfer of the data frame can be started at time T3 when the destination address set in the data frame is read and it can be determined whether or not to transfer. As a result, the data frame transfer delay time from the information processing device 6 to the information processing device 7 can be reduced to T1 + Td1 + T3 + Td2 + T3 + Td3 even though the data transmission rate of the trunk LAN 3'is the same as that of the branch lines LAN1 and LAN2.

[0021]

However, the above-mentioned conventional techniques have the following problems. (1) Problems of the first conventional example In the first conventional example, the data frame received from the branch LAN is stored once in the network relay device, the data format is converted, and then transmitted to another branch LAN. Therefore, it is affected by the data packet accumulation time of the network relay device. Further, the software executed by the processor is affected by the comparison time of the transfer destination address. Therefore, FD is connected to the trunk LAN.
Although a high-speed LAN such as DI is adopted, the delay time from the transmission of data from the transmission source to the reception of the data frame by the transmission partner becomes large.

(2) Problems of Second Conventional Example In the second conventional example, the data packet to be relayed by the network relay device is relayed by the cut-and-through method without being stored once. Then branch line LAN
There is a restriction that the data transfer capability and protocol of the main line LAN and the main line LAN must be the same. As a result, the data transfer amount of each branch LAN increases, and as a result, the trunk LAN
The data transfer amount of 10 Mbps is slightly exceeded.
As a result, the data frame transfer delay time from the transmission source to the transmission partner increases.

Since no transmission data is stored,
If a transfer error occurs during the transfer of the data frame, the data frame must be retransmitted from the transmission source. Therefore, the occurrence of a transfer error wastes the data transfer capability of the network. On the other hand, when a high-speed LAN having the same capacity as the trunk LAN is used as the branch LAN, there is a problem that the existing branch LAN system cannot be used and the data transfer capacity of the newly installed branch LAN becomes unnecessarily large. It was The present invention has been made in view of the above points, and an object of the present invention is to provide a LAN relay device capable of shortening the relay time of a data frame and increasing the capacity of a main LAN.

[0024]

A LAN relay device according to a first aspect of the present invention connects a trunk LAN group composed of a plurality of LANs having the same specifications as a branch LAN, and a plurality of LANs constituting the trunk LAN group. Selecting means for selecting a LAN to be used for transferring the data transferred from the branch line LAN, and relay means for relaying the data received from the branch line LAN to the LAN in the trunk LAN group selected by the selecting means. It consists of and. In the LAN relay device of the second invention, the selecting means in the first invention inputs a part of a plurality of bit strings obtained by dividing the destination address included in the data received from the transmission source as an address, and each of the 1-bit Based on the storage means for storing information and the information stored in the storage means, the other part of the plurality of bit strings is input as an address, and the main line LA
And a selection information storage means for storing information for selecting the N group.

[0025]

In the LAN relay device of the first aspect of the invention, the destination address is extracted from the data frame sent from the information processing device via the branch LAN, and the selecting means selects the trunk LAN group according to the destination address. LA to configure
One of N is selected. And the selected LAN
Is connected to the branch line LAN by the relay means. A data frame in the middle of communication is stored inside the LAN relay device and is retransmitted when a data error occurs. In the LAN relay apparatus of the second invention, the destination address is divided into a plurality of bit strings, and a storage means is provided for each divided bit string. Then, one storage means is used as selection information storage means for storing selection information for selecting a LAN of the main LAN group in the first invention. On the other hand, another storage means is used to input a part of the bit string obtained by dividing the destination address and store the presence / absence of information in the selection information storage means. As a result, the LAN selection information for each destination address can be quickly read without increasing the storage capacity of each storage unit.

[0026]

Embodiments of the present invention will now be described in detail with reference to the drawings. (First Invention) FIG. 1 shows a first embodiment of a LAN relay device of the present invention.
2 is a block diagram of an embodiment of FIG. The illustrated system includes branch LANs 101 and 102 and a trunk LAN group 103.
The trunk LAN group 103 is composed of a plurality of LANs having the same data transfer capability and protocol as the branch LANs 101 and 102. In the case of FIG. 1, the number of trunk LANs is
There are three. Network relay device 104, 10
Reference numeral 5 connects the branch line LAN 101 and the trunk line LAN group 103, and the branch line LAN 102 and the trunk line LAN group 103, respectively.

The network relay devices 104 and 105 are
Selection means 401, 501, relay means 402, 5 respectively
It consists of 02. The selecting means 401 and 501 are branch line LANs.
The branch line LAN 1 is connected to a main LAN group 103 composed of a plurality of LANs having the same specifications as those of 101 and 102, and the branch line LAN 1 among the plurality of LANs forming the main LAN group 103.
L used to transfer the data transferred from 01 and 102
Select AN. Specific configurations of the selecting means 401 and 501 will be described later. Relay means 402, 502
Is the main line LA selected by the selection means 401, 501.
The data received from the branch LANs 101 and 102 is relayed to the LAN in the N group 103. This relay means 402, 50
The specific configuration of No. 2 will also be described later. Information processing device 1
06 and 107 are connected to branch lines LAN 101 and 102, respectively.

FIG. 8 shows an example of a specific internal structure of the network relay device 104 shown in FIG. The illustrated apparatus includes a LAN interface control unit 108 and LAN interfaces 109-1 to 109-4. The LAN interface 109-1 is connected to the branch LAN 101, and the LAN interfaces 109-2 to 109-4 are
It is connected to the trunk line LANs 103-1 to 103-3. These LANs are all the same and are, for example, Ethernet LANs. LAN interface 109-1
4 correspond to the selecting means 401 and 402 of FIG. The LAN interface control unit 108 corresponds to the relay units 402 and 502 in FIG. 1, and has a function of selecting and connecting each LAN interface 109-1 to 4 in the network relay device 104.

The LAN interface 109-1 includes an address comparison section 110, a transfer address table 111, a driver element 112, a transmission buffer 113, and a receiver element 1.
14, the reception buffer 115. Similarly, the LAN interface 109-2 includes an address comparison unit 116, a transfer address table 117, a driver element 118, a transmission buffer 119, a receiver element 120, and a reception buffer 1.
It consists of 21. Also, the LAN interface 109-
Although not shown, 3 and 4 are the same as the LAN interfaces 109-1 and 109-2.

Next, the data frame transfer operation in this embodiment will be described with reference to FIG. In FIG. 1, it is assumed that a data frame is transferred from the information processing device 106 to the information processing device 107. First, similarly to the conventional example in FIG. 2, the information processing apparatus 106 sends a data frame addressed to the information processing apparatus 107 onto the branch line LAN 101. Then, the network relay device 104 receives the data frame and checks the destination address. Then, it is determined whether or not the transfer should be made to the trunk LAN group 103 side. Details of this determination will be described later in the description of FIG. In the case of this operation example, since the received data frame is addressed to the information processing device 107, the network relay device 104 operates to relay the data frame to the trunk LAN group 103 side. Further, the network relay device 105 receives the data frame from the trunk LAN group 103, and checks the destination address of the received data frame. Then, the data frame is connected to the branch line LAN.
Then, the information processing apparatus 107 receives the data frame.

Next, the internal operation of the network relay device 104 in the above operation will be described with reference to FIG. Here, the data frame received by the LAN interface 109-1 is the LAN interface 109-2.
Shall be relayed to. First, the data frame is L
It is received by the receiver 114 of the AN interface 109-1. The bit string of the received data frame is sequentially stored in the reception buffer 115. Then, when the destination address of the data frame is stored in the reception buffer 115, the reception buffer 115 instructs the address comparison unit 110 to receive the data frame and compare the addresses. The address comparison unit 110 determines the destination address of the data frame and the transfer address table 1
11 is compared to determine whether or not the data frame should be relayed inside the network relay device 104. If the destination address instructed by the reception buffer 115 matches the contents of the non-transfer address in the transfer address table 111, the data frame is LAN
Discarded by interface 109-1.

In this operation example, the data frame is L
Since it should be transferred to the AN interface 109-2, the destination address is transferred to the transfer address table 111.
Will match the forwarding address of. Then, the address comparison unit 110 causes the LAN interface control unit 108.
Is notified that the data frame to be relayed by the network relay device 104 is received by the LAN interface 109-1. Upon receiving this notification, the LAN interface control unit 108 checks the states of the LAN interfaces 109-2 to 109, instructs the LAN interface 109-1 to transfer the data frame to the LAN interface 109-2, and It instructs the LAN interface 109-2 to transmit the data frame transferred from the LAN interface 109-1.

LAN interface 1 receiving this instruction
09-1 reads the data frame being received from the reception buffer 115 composed of a shift register,
The transfer to the LAN interface 109-2 is started.
In the LAN interface 109-2, the bit string of the transferred data frame is sequentially transferred to the driver element 12
1 to the main LAN 103-1. At this time, the LAN interface 109-2 transfers the data frame and sends it to the transmission buffer 11
9 are sequentially stored. The storage of the data frame in the transmission buffer 119 is performed by the trunk LAN 103.
This is because the data frame is retransmitted when a data frame transfer error (for example, packet collision) occurs on the -1 side.

When the transfer of the data frame is completed by the LAN interface 109-2, the LAN interface 109-2 notifies the LAN interface control unit 108 of the end of the transfer of the data frame. As a result, the relay operation in the network relay device 104 ends. In such a relay operation, the LAN interfaces 109-1 to 109-4 inside the network relay device 104
Since the protocols of the LANs connected to the same are all the same, the format conversion of the data frame, which was necessary in the first conventional example, is not necessary.

On the other hand, the network relay device 1 shown in FIG.
When the data frame sent from the LAN interface 109-2 of the network relay device 104 to the trunk LAN 103-1 is received at 05, the data frame is transferred to the branch line LAN 102 by the same operation as that of the network relay device 104 described above. The data frame transferred to the branch line LAN 102 is received by the information processing device 107. From the above, the information processing devices 106 to 10
The operation of transferring the data frame to 7 is completed.

(Second Invention) FIG. 9 shows the address comparison unit 1 of the LAN interface in the first embodiment of the present invention.
10 and the structure of the transfer address table 111, that is, FIG.
A specific configuration example of the selecting means 401 and 501 will be shown. In FIG. 9, the LAN interface is provided with an address comparison unit 110 and a transfer address table 111. The address comparison unit 110 includes a destination address register 125, a memory access control unit 126, a comparison unit 127,
It comprises an interface number register 128. The destination address register 125 stores the destination address of the received data frame. This address is a 48-bit L specified by the international standard IEEE802.
It is an AN address.

The memory access control unit 126 controls the memory 1
29-1, 129-2, 129-3, the interface number register 128 and the latch 130 are controlled. The comparison unit 127 uses the transfer address table 1 based on the address stored in the destination address register 125.
The information read from 11 is compared with the contents stored in the interface number register 128. The interface number register 128 stores the own number of the LAN interface. For example, if the LAN interface 109-1 stores "00",
The LAN interface 109-2 stores "01", and the LAN interface 109-3 stores "10".
If it is -3, "11" is stored.

The transfer address table 111 is stored in the memory 1
29-1, 129-2, 129-3 and a latch 130. The memories 129-1 and 129-2 (storage means) are
Each is composed of 1 Mbit × 1 DRAM. Memory 1
29-3 (selection information storage means) is composed of a 256 × 4 bit DRAM. The latch 130 is a memory 129-
The information read from Nos. 1 and 129-2 is held. 48
Because it stores the bit length of the LAN address, simply 48
Using a memory device with a book address line,
Even if the bit length of the information stored for each LAN address is 1 bit, a terabit scale memory element is required, which is not feasible. For this reason,
In this embodiment, a 48-bit long LAN address is shown in FIG.
20 bits from lower to higher as shown in
Bit and 8-bit addresses are divided. Then, the bit length of the information to be stored for each upper address of 8-bit length is set to 4 bits, and this is stored in the memory 129-3. Further, the information corresponding to the middle and lower addresses of 20-bit length is stored in the memories 129-1 and 129-2.

The 1-bit output data of the memories 129-1 and 129-2 indicates whether or not the information corresponding to the input middle and lower addresses is stored in the memory 129-3. For example, when the output data is “1”, the information corresponding to the input middle and lower addresses is stored in the memory 129-3, and when the output data is “0”,
It is not stored. That is, in the case of "0",
It indicates that the address is a new destination. However, the memories 129-1 and 129-2 each have only the middle 20 bits and the lower 20 bits of the LAN address of the destination. Therefore, the output data of the memories 129-1 and 129-2 are held in the latch 130, and when there are middle and lower addresses, the upper addresses corresponding to them are input to the memory 129-3, so that the LAN It is checked whether the information corresponding to the address is stored in the memory 129-3.

That is, the output data of the memory 129-3 is
It is 4 bits long, and the upper 2 bits are the LA that was received.
It indicates whether the N address is a transfer address, a non-transfer address, or a new address. For example, when the value of the upper 2 bits is “10”, the transfer is set, when the value is “01”, the transfer is not performed, and when the value is “00”, the new address is set. On the other hand, the lower 2 bits of the output data of the memory 129-3 indicate the internal LAN interface number of the network relay device. That is, "00" indicates the LAN interface 109-1, "01" indicates the LAN interface 109-2, "10" indicates the LAN interface 109-3, and "11" indicates the LAN interface 109-. 3 is shown.

The operation of checking the destination address when a data frame is received will be described below with reference to FIGS. 9, 10 and 11. First, when the LAN interface 109-1 receives a data frame, the destination address of the data frame is stored in the destination address register 125. Then, the memory access control unit 1
26 operates, and the destination address register 128 is used as a control signal for reading the memories 129-1, 129-2 and an address for reading the memories 129-1, 129-2.
A total of 40 bits of the middle and lower bits of the address set to are output (time T1 in FIGS. 11A and 11B). As a result, the information stored in the memories 129-1 and 129-2 is read (time T1 in FIG. 11D). The memory access control unit 126 outputs a latch signal to the latch 130 and holds the data read from the memories 129-1 and 129-2 in the latch 130 (FIG. 11).
(C) Time T1).

When the data shown in FIG. 11D is held in the latch 130, the memory access control unit 126 causes the latch 1
The data held in 30 is output to the comparing unit 127, and the upper 8 bits of the LAN address stored in the destination address register 125 are stored in the memory 129-3.
Is output as the read address (time T2 in FIG. 11E). At the same time, a read control signal is output to the memory 129-3 (FIG. 11 (f) time T2). Then, at the timing when the data is output from the memory 129-3, the memory access control unit 126 outputs a timing signal for sampling the data to the comparison unit 127 and the interface number register 128 (FIG. 11 (g), time T).
2).

As a result, the LAN interface can judge whether the received data frame should be relayed or discarded, and at the same time, if it should, the LAN interface number to which the data frame should be transferred is shown in FIG. It can be obtained in two memory access cycle times as shown in FIG. Therefore, the determination time, which conventionally required a long time due to the determination loop by software processing, is greatly reduced. In addition, the transfer address table 11
Similarly to the above-described operation, the update work of 1 etc. can be performed in two memory access cycle times (memory write).

On the other hand, in the conventional technique, as shown in FIG. 4, the comparison processing of the transfer address table at the time of checking the destination address is performed by the software executed by the processor 10, and the loop processing is performed. Therefore, the addresses of the transfer address area 12 and the non-transfer address area 13 are sequentially compared with the address of the destination address register 9. Therefore, the comparison operation may take a very long time, and the relay time in the network relay device may be long. Further, as the scale of the network system increases, it is necessary to enlarge each area of the transfer address table 11, which causes a problem that the address comparison operation time becomes longer and longer. As described above, the second invention solves this problem.

FIG. 12 is a time chart explaining the operation of the apparatus of the first embodiment of the present invention. The operation along the time axis of FIG. 12 is the same as the operation of the conventional technique described with reference to FIG. 7, but the transfer address comparison unit 1 shown in FIGS.
The operation of 10 shortens the transfer destination address comparison time in the network relay device. As a result, it becomes possible to perform the relay in a shorter time than the example of the related art of FIG. In addition, the data frames received by the network relay devices 104 and 105 are transmitted to another LAN (in the case of the above example, LA
When transferring to the N interface 109-2), the data frame is transferred and also stored in the transmission buffer of the LAN interface. Therefore, if a transfer error occurs in the transfer, the data in which the transfer error occurs from the LAN interface. The frame can be retransmitted. Therefore, it is not necessary to bother to retransmit the data frame from the information processing device of the transmission source, waste of the transfer capacity of the network can be eliminated, and the retransmission time of the data frame can be shortened.

In the first embodiment described above, the network relay devices 104 and 105 are both trunk lines LA.
The case where one branch line LAN 101, 102 is connected to the N group 103 has been described, but the present invention is not limited to this, and a plurality of branch line LANs may be connected. Further, in FIG. 9, the LAN interfaces 109-2 to 109-4 on the trunk LAN side may not be specified for the trunk LAN but may be used for the branch LAN. Further, in the above-described first embodiment, each LAN interface is provided with the transfer address table, but only one such network address is provided in the network relay device and each L interface is provided.
There is no problem even if they are shared by the AN interface.

FIG. 13 shows a second embodiment of the present invention.
In FIG. 13, a trunk LAN 13 is used as a trunk LAN group.
1-133 are provided. The main LAN 131 is
Ethernet transceivers 134-1 to 134-4 are connected. Ethernet transceivers 135-1 to 13-4 are connected to the trunk LAN 132. And the main line LA
Ethernet transceiver 136-1 to N133
4 is connected.

The Ethernet transceiver 134-
1, 135-1 and 136-1 are connected to the network relay device 137-1 via transceiver cables 138-1, 138-2 and 138-3, respectively. Ethernet transceivers 134-2, 135-2, 13
6-2 is a transceiver cable 139-1,
It is connected to the network relay device 137-2 via 139-2 and 139-3. The Ethernet transceivers 134-3, 135-3, 136-3 are transceiver cables 140-1, 140-2, 140-, respectively.
3 is connected to the network relay device 137-3. Ethernet transceivers 134-4, 135
-4 and 136-4 are transceiver cables 1 respectively
It is connected to the network relay device 137-4 via 41-1, 141-2, 141-3. The network relay devices 137-1 to 13-4 are respectively connected to the branch line LA.
Information processing devices 142-145 via N147-150
It is connected to the.

In FIG. 13, the operation when transmitting a data frame from the information processing device 142 to the information processing device 144 will be described. This operation is basically the same as the operation of the first embodiment shown in FIG. First, the information processing device 142
When requesting data transfer, acquires the access right of the branch line LAN 147 and transmits the data frame corresponding to the transmission request to the branch line LAN 147. Then, the network relay device 137-1 receives this data frame. In the network relay device 137-1, after checking the destination address, the trunk LANs 131 to 13 are selected by the trunk LAN selection function similar to that of the first embodiment.
The main LAN 131 to be used is selected from the three. Then, the data frame is transmitted to the trunk LAN 131.

Then, the network relay device 137-
In Nos. 2 and 4, the data frame is received from the trunk LAN 131, but since the destination address of the data frame matches the address stored in the non-transfer address area,
It judges that it is not necessary to relay and discards the received data frame. The network relay device 137-3 receives the data frame from the trunk LAN 131, and since the destination address of the data frame matches the address stored in the transfer address area, the LAN interface is set so as to transfer the data frame to the branch line LAN 149. Connect. Then, the information processing device 144 uses the branch line LAN1.
Receive a data frame from 49. This completes the transmission of the data frame via the network.

On the other hand, at the same time when the information processing device 142 transmits a data frame, the information processing device 1
When 45 transmits a data frame to the information processing device 143, the data frame is transmitted via the network relay devices 137-4 and 2 similarly to the above-described operation of transmitting the data frame from the information processing device 142 to the information processing device 144. It is possible to send. That is, in transmitting the latter data frame, the network relay device 137-4
Then, a trunk LAN 132 or 133 other than the trunk LAN 131 used for transmitting the former data frame.
It is possible to select to transmit the data frame. In the second embodiment described above, the LA on the main line side
Although three LANs 131 to 133 are used for N, the present invention is not limited to this, and it is possible to use any number of LANs such as two or four or more. When adding a LAN to the main LAN side, it is only necessary to add the same network interface device as the LAN interface currently used.

[0052]

(1) As described above, L of the present invention
According to the AN relay device, since a plurality of LANs having the same protocol as the branch LAN connected to the information processing device are prepared and used as the trunk LAN, the efficiency can be improved without using the high speed trunk LAN. Data transfer can be performed. In addition, the main LAN is a multiple LAN
Therefore, if the load on the network system increases and the capacity of the trunk LAN needs to be improved, it is only necessary to increase the number of LANs used on the trunk LAN side. In that case, it is not necessary to replace the network relay device, and the system performance can be improved only by adding the LAN interface used in the current network relay device.

(2) Furthermore, the branch line LAN and the main line L described above
In the network relay device connecting the AN group, by storing the information by using the bit string obtained by dividing the received destination address as the input address, the selection information of the trunk LAN can be quickly accessed, and the data communication via the network can be performed. The speed of can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of a LAN relay device of the present invention.

FIG. 2 is a block diagram of an example of a conventional LAN relay device.

FIG. 3 is a time chart showing an operation example of a conventional technique.

FIG. 4 is an explanatory diagram of an internal configuration example of a conventional transfer address comparison unit.

FIG. 5 is an explanatory diagram of a conventional network configuration example.

FIG. 6 is a block diagram of another example of a conventional LAN relay device.

FIG. 7 is a time chart showing another operation example of the conventional technique.

FIG. 8 is a block diagram showing an internal configuration example of a network relay device according to the present invention.

FIG. 9 is a configuration diagram of an address comparison unit and a transfer address table according to the present invention.

FIG. 10 is an operation explanatory diagram of a portion according to the second invention of the present invention.

FIG. 11 is a time chart explaining the operation of checking the destination address of FIG.

FIG. 12 is a time chart explaining the operation of the first embodiment of the present invention.

FIG. 13 is a block diagram of a second embodiment of the LAN relay device of the present invention.

[Explanation of symbols]

 101, 102 Branch line LAN 103 Main line LAN group 104, 105 Network relay device 106, 107 Information processing device

Claims (2)

[Claims] 1. A plurality of LANs having the same specifications as a branch line LAN
Is connected to the main line LAN group, and the main line LA is connected.
Selection means for selecting a LAN to be used for transferring the data transferred from the branch LAN among a plurality of LANs constituting the N group, and L in the trunk LAN group selected by the selection means.
A LAN relay device comprising relay means for relaying data received from the branch LAN to the AN. 2. The selecting means inputs a part of a plurality of bit strings obtained by dividing a destination address included in data received from a transmission source as an address, and stores 1-bit information for each of the storage means. Based on the information stored in the storage means, another part of the plurality of bit strings is input as an address, and the main line L
2. The LAN relay device according to claim 1, further comprising selection information storage means for storing information for selecting an AN group.