JPH0923245A - Network connection device - Google Patents

Abstract

(57) [Summary] [Purpose] When a large amount of data is divided into a plurality of transmission frames and transmitted to terminals on other networks, the transmission frames are transmitted in order. A transmission history memory 10 for storing an address pair of a destination address of a destination terminal and a source address of a source terminal and a communication line is provided in each storage area 10a, and a transmission line 2 is provided.
Address pair of transmission frame input from a [DA ₀ , S
A ₀ ] is detected, and the storage area 10a in which the detected address pair is stored is detected from the transmission history memory 10. Further, the communication line 5 stored in the detected storage area 10a is designated as the transmission line of the input transmission frame.
Then, when the storage area is not detected, the communication line for transmitting the transmission frame is separately designated, and the detected address pair and the designated communication line are written in the new storage area 10a of the transmission history memory 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-network connecting device for connecting networks via multiplexed signal lines.

[0002]

2. Description of the Related Art In a LAN (Local Area Network) or a WAN (Wide Area Network), for example, a large number of terminals such as computers and facsimiles are connected to a transmission line of the network. When more than the limit number of terminals are connected to one network, the traffic amount (transmission amount) on the transmission path increases and the transmission efficiency of data transmission between the terminals decreases. Further, there is a certain limit on the extension distance of the transmission path.

Therefore, a plurality of independent networks are constructed, and data transmission between the networks is performed by an inter-network connection device that connects the networks.

For example, when data is transmitted from a terminal on one network to a terminal on another network, a destination address DA ₀ that specifies the destination terminal in the transmission frame is set.
Also, the transmission source address SA ₀ for specifying the transmission source terminal and the transmission data are incorporated and transmitted to the transmission path. The inter-network connection device takes in the transmission frame output to the transmission path and, if the transmission frame is a transmission frame to be transmitted to a terminal of another network, transmits this transmission frame to the destination network via the communication line. Transfer to.

The destination terminal of the destination network takes in this transmission frame whose own address is designated as the destination address. When the frequency of data transmission between the networks is high, the communication lines connecting the networks are multiplexed so that a large number of transmission frames can be simultaneously transmitted between the networks.

[0006]

However, even in an inter-network connecting device for transferring a transmission frame between a plurality of networks connected by a multiplexed communication line, the following problems to be solved still remain. there were.

That is, among data transmitted from terminals of one network to another network, there is data that is too long to be accommodated in one transmission frame. In such a case, the data to be transmitted is divided into a plurality of pieces, and each of the divided pieces of data is incorporated into an individual transmission frame and transmitted. Then, on the receiving side, the data sequentially transmitted in the individual transmission frames are combined to reproduce the original data having the original data length.

The transmitting terminal naturally sends out the respective transmission frames including the respective divided data to the transmission path in the order of the data. The inter-network connection device transmits each sequentially input transmission frame to the network to which the destination terminal belongs via the communication line.

Generally, which communication line is used to transmit a transmission frame depends on when the transmission frame is captured.
A free communication line that is not communicating is automatically selected. Therefore, a series of transmission frames to be transmitted to the same destination terminal may be dispersed and transmitted to a plurality of communication lines.

Since each communication line connecting the networks is not a dedicated line in many cases, the time required to reach the partner network may differ depending on the type of communication path or line.

Therefore, even if a series of transmission frames are transmitted from the inter-network connecting device to the same network in data order, the transmission frames may arrive at the partner network in a different order from the transmission order.

In such a case, there arises a problem that the data cannot be correctly reproduced at the destination terminal which finally receives the series of transmission frames and reproduces the original data. Further, in this case, since the transmission destination terminal (reception terminal) transmits the retransmission request to the transmission source terminal, the processing load on the transmission source terminal and the transmission destination terminal increases.

The present invention has been made in view of such circumstances, and by storing and holding the transmission history,
When sending from the same source terminal to the same destination terminal,
The same communication line is automatically selected, each transmission frame always reaches the destination terminal in the correct order, the reliability of data transmission can be improved, the number of retransmission occurrences is suppressed, and the entire network including the terminal and the communication line It is an object of the present invention to provide an inter-network connection device capable of improving the communication processing efficiency of the entire network system including

[0014]

SUMMARY OF THE INVENTION The present invention is designed to be inserted into a multiplexed communication line connecting between a plurality of networks to transmit data from a terminal of one network to a terminal of another network. It is applied to an inter-network connection device that inputs a transmission frame output from a source terminal to a transmission line of a network and transmits the input transmission frame to a transmission line of a network of a destination terminal via a communication line.

The present invention further comprises a transmission history memory having a plurality of storage areas, each storage area storing an address pair of a destination address of a destination terminal and a source address of a source terminal and a communication line. Detecting means for detecting an address pair of a transmission frame input from the transmission path, storage area detecting means for detecting a storage area in which the address pair detected by the detecting means is stored, in the transmission history memory, and this storage Communication line designating means for designating a communication line stored in the storage area detected by the area detecting means as a transmission line of the input transmission frame, and a transmission frame when the storage area is not detected by the storage area detecting means And a new registration means for separately designating a communication line for transmitting the data, and writing the detected address pair and the designated communication line in a new storage area of the transmission history memory. There.

In another aspect of the invention, the network connection device has a plurality of storage areas, and each storage area has an address pair of a destination address of a destination terminal and a source address of a source terminal. A transmission history memory for storing the protocol type of the transmission frame and the communication line, a detection unit for detecting the address pair and the protocol type of the transmission frame input from the transmission line, and the address pair and the protocol detected by the detection unit. A storage area detecting means for detecting a storage area in which the type is stored from the transmission history memory, and a communication line stored in the storage area detected by the storage area detecting means are used as the transmission line of the input transmission frame. Communication line specifying means for specifying and communication line for transmitting a transmission frame when the storage area is not detected by the storage area detecting means Separately specified, detected address pair, and a new registration means for writing a communication line and protocol type and specify the new memory area of the transmission history memory.

[0017]

In the inter-network connecting device configured as described above, from the destination address and the source address in each transmission frame once transmitted from the inter-network connecting device to the destination network via one communication line. The following address pairs and used communication lines are stored in the respective storage areas of the transmission history memory.

Therefore, next, when a transmission frame having the same destination address and the same transmission source address is input, the address pair of this transmission frame is detected, and the storage area of the transmission history memory in which the detected address pair is stored. The corresponding transmission frame is transmitted to the communication line stored in.
Therefore, the transmission frame is transmitted via the same communication line as the previously transmitted communication line.

Therefore, even if a large amount of data is divided into a plurality of transmission frames and transmitted from a terminal of one network to a terminal of another network,
Since each transmission frame is transmitted via the same communication line, the transmission order of each transmission frame at the source terminal,
The reception order of the transmission frames at the destination terminal (reception terminal) does not become inconsistent.

In addition, in another invention, in each storage area of the transmission history memory, in addition to the address pair consisting of the destination address and the transmission source address and the communication line used, the protocol of the transmission frame is concerned. Another is also stored.

Further, after determining the protocol type of the input transmission frame, an address pair consisting of a destination address and a source address for which the setting place in the transmission frame is specified by the corresponding protocol type is detected.

Therefore, even in a network in which a plurality of types of protocols are adopted between the source terminal and the destination terminal, the previously used communication line is used again for each protocol type. Can be transmitted. Therefore, similarly to the invention described above, the transmission order of the transmission frames at the transmission source terminal and the reception order of the transmission frames at the transmission destination terminal (reception terminal) do not become inconsistent.

[0023]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic diagram showing a network system in which the network connection device of the embodiment is incorporated. This network system is composed of two networks 1a and 1b such as a LAN.

In one network 1a, a plurality of terminals 3a and one inter-network connection device 4a are connected to the transmission line 2a. Further, in the other network 1b, a plurality of terminals 3b are provided on the transmission line 2b.
And one inter-network connection device 4b is connected.

A plurality of communication lines 5 are connected between the inter-network connecting device 4a and the inter-network connecting device 4b. Each of the communication lines 5 is composed of a dedicated line or a general public line.

FIG. 1 is a block diagram showing a schematic configuration of the inter-network connecting device 4a. To the system bus 6, line control units 7a and 7b, a network control unit 8, a frame memory 9, a transmission history memory 10 and a bus arbiter 11 are connected. A CPU 13, a local memory 14, and a clock circuit 17 for keeping the present time are connected to a CPU bus 12 connected to the bus arbiter 11.

Each of the line control units 7a and 7b controls transmission / reception of a transmission frame with respect to each communication line 5 connected to the other inter-network connecting device 4b. The network control unit 8 controls transmission / reception of transmission frames for the network 2a on the self side. Further, the frame memory 9 temporarily stores each transmission frame transmitted / received to / from each communication line 5 and the transmission path 2a. That is, each line control unit 7
When receiving a transmission frame from each communication line 5 or transmission line 2a, the a and 7b and the network control unit 8 once write the frame into the frame memory 9.

The bus arbiter 11 includes the system bus 6 and C.
Arbitration of the right to use the bus with the PU bus 12. The local memory 14 stores various programs for executing transmission control for the transmission frame performed by the CPU 13.

The other inter-network connecting device 4b has almost the same structure as the above-mentioned inter-network connecting device 4a. FIG. 4 shows the transmission lines 2a of the networks 1a and 1b.
It is a figure which shows the transmission format in case each terminal 3a, 3b connected to 2b transmits data to another terminal.

FIG. 4A shows a format of a transmission frame 15 (bridge frame) of a protocol (protocol type number PNO = 1) between terminals when the repeater has a bridge function. A destination address DA ₀ (MAC address) that identifies the destination terminal is set at the top, and a source address SA ₀ that identifies the source terminal is set at the second. Then, the protocol type PNO (= 1) adopted by the transmission frame 15 is set next, the transmission data is incorporated after that, and finally the CR is set.
A check code such as C is set.

FIGS. 4B and 4C show transmission frames 16a, 16b (IP) of different protocols (protocol type number PNO = 2) between terminals when the repeater has an IP router function. Frame) format.

This protocol (protocol type number PN
In the case of O = 2), for example, when data is transmitted from the terminal 3a of the one network 1a to the terminal 3b of the other network 1b, the transmission source terminal, as shown in FIG. The address of the inter-network connection device 4a as a relay device to the destination address DA
_Incorporated as _I , the source address S that shows itself second
Set A ₀ . Next, the protocol type number PNO = 2
Set. Further, this protocol type number PNO =
2 is followed by a destination address DA that identifies the destination terminal 3b
₀ and the source address SA ₀ are incorporated, and then the transmission data and the check code are incorporated. The transmission frame 16a having such a configuration is output to the transmission line 2a.

The inter-network connecting device 4a which has received the transmission frame 16a transmits it to the other inter-network connecting device 4b via the communication line 5. The inter-network connecting device 4b determines the start and next addresses of the received transmission frame 16a as shown in FIG.
The destination address DA ₀ indicating self rewrites the source address SA _I showing a (inter network connection device 4b),
It is sent to the transmission line 2b.

As described above, when the protocol types are different,
The formats of the transmission frames 15, 16a and 16b are different. In the transmission history memory 10, as shown in FIG. 3, a plurality of storage areas 10a are formed. And
In each storage area 10a, transmission frames 15, 16a,
The protocol type PNO of 16b, the destination address DA ₀ for specifying the destination terminal, the source address SA ₀ for specifying the source terminal, the communication line number for specifying the communication line 5, and the transmission time TS are stored. In the initial state, nothing is stored in each storage area 10a.

In the inter-network connecting device 4a having such a configuration, the network control unit 8 of the network 1a to which the self is connected transmits the frame to be transmitted from the terminal 3a of the own network 1a to the terminal 3b of the other network 1b. When 15 and 16a are received and written in the frame buffer 9, the CPU 13 is configured to execute a transmission process of the received transmission frame to the communication line 5 according to the flowchart shown in FIG.

When the flow chart starts, S (step) 1
At, the protocol type PNO of each transmission frame 15, 16a written in the frame buffer 9 is read. Even if the protocol type is different, the protocol type can be easily read because it is set at the same position on the transmission frames 15 and 16a.

When the protocol types are determined, the set positions of the destination address and the source address for identifying the destination terminal 3b and the source terminal 3a on the transmission frames 15 and 16a are uniquely determined, so that the received transmission frame The address pair [DA ₀ , SA ₀ ] of the destination address DA _{0 of} 15 and 16a and the source address SA ₀ is read (S
2).

Next, the read address pair [DA ₀ , SA
₀ ] and the read-out protocol type PNO are simultaneously stored in the transmission history memory 10 (S3).

When the corresponding storage area 10a does not exist, it is determined that data has not been transmitted from the same terminal 3a to the same terminal 3b by the same protocol in the near past.
In this case, the process proceeds to S4, and the optimum communication line 5 for transmitting the current transmission frame to the other network 1b is selected. Specifically, the communication line 5 having the smallest amount of transmitted / received data at the present time is selected.

Next, if there is a free storage area 10a in which the information such as the address pair [DA ₀ , SA ₀ ] is not stored in the transmission history memory 10, the corresponding storage area 1
0a, the protocol type PNO read from the transmission frames 15 and 16a, the address pair [DA ₀ , SA
₀ ] and the selected communication line number are written (S7).

If there is no free storage area 10a in the transmission history memory 10, the oldest transmission time TS
Storage area 10a is selected (S6), and the transmission frame 1
The protocol type PNO, the address pair [DA ₀ , SA ₀ ] and the selected communication line number read from 5, 16a are written (S7).

Then, the transmission frame 1 received this time is sent to the line control unit 7a (7b) of the selected communication line 5.
5, 16a are transferred. The line control unit 7a (7b) which has received the transmission frames 15 and 16a transmits them to the communication line 5 connected to itself (S8). Next, the current time is read from the clock circuit 17, and the transmission time TS is stored in the corresponding storage area 10a.
Write as (S9).

When the storage area 10a in which the protocol type PNO and the address pair [DA ₀ , SA ₀ ] read from the received transmission frames 15 and 16a are stored is found in the transmission history memory 10 in S2. , Go to S10,
The communication line number stored in the corresponding storage area 10 is read out, and the currently received transmission frames 15 and 16a are transferred to the line control unit 7a (7b) corresponding to the communication line 5 designated by this communication line number. . Transmission frame 15,1
The line control unit 7a (7b) having received 6a transmits it to the communication line 5 connected to itself (S8). Next, the transmission time TS stored in the corresponding storage area 10a is set to the clock circuit 17
It is updated to the new transmission time TS which is the current time read from (S9).

Therefore, in each storage area 10a of the transmission history memory 10, the latest communication time TS at which the corresponding protocol type PNO and the address pair [DA ₀ , SA ₀ ] are communicated.
Is stored.

In the inter-network connecting device 4a thus constructed, once. Each transmission frame 1 input from the network 1a connected to itself and transmitted to the inter-network connecting device 4b of the partner network 1b via one communication line 5 selected as the optimum at that time
5, 16a, an address pair [DA ₀ , SA ₀ ] consisting of a destination address DA ₀ and a source address SA ₀ , a protocol type PNO, a communication line number identifying the communication line 5 used, and a transmission time TS are transmitted. History memory 10
Is stored in one storage area 10a.

Therefore, next, the same protocol type P
NO, when the transmission frames 15 and 16a of the same address pair [DA ₀ , SA ₀ ] are input, this transmission frame 1
5, 16a protocol type PNO and address pair [D
A ₀ , SA ₀ ] is detected, and the corresponding transmission to the communication line 5 stored in the storage area 10a of the transmission history memory 10 in which the detected protocol type PNO and the address pair [DA ₀ , SA ₀ ] are stored. Frames 15 and 15a are transmitted. Therefore, the transmission frames 15 and 16a are transmitted via the same communication line 5 as the previously transmitted communication line 5.

Therefore, even if only one network 1
From the terminal 3a of a to the terminal 3b of the other network 1b, a large amount of data is transmitted to a plurality of transmission frames 15, 16a.
Each transmission frame 15.1
Since 6a is transmitted via the same communication line 5, the transmission order of the transmission frames 15 and 16a at the transmission source terminal 3a and the reception order of the transmission frames 15 and 16b at the transmission destination terminal (reception terminal) 3b are the same. There is no discrepancy.

Therefore, in the receiving terminal 3b, the transmission data divided into a plurality of transmission frames 15, 16a and 16b and transmitted are combined so that the original data is always reproduced correctly and the reliability of data transmission can be improved. .

In the apparatus of the embodiment, when the protocol type PNO, the address pair [DA ₀ , SA ₀ ] and the communication line number are stored in all the storage areas 10a formed in the transmission history memory 10, next, New transmission frame 1
When 5 and 16a are input, the new protocol type PNO, the address pair [DA ₀ , SA ₀ ] and the communication line 5 are overwritten in the oldest storage area 10a of the transmission time TS. Therefore, the storage capacity of the communication history memory 10 can be effectively used.

The present invention is not limited to the apparatus of the above embodiment. In the apparatus of the embodiment, the protocol type PNO is read from the transmission frame.
For example, when all the terminals 3a and 3b incorporated in the networks 1a and 1b perform data transmission using the same protocol, the address pair [DA
₀ , SA ₀ ] is fixed, it is not necessary to read the protocol type PNO. In this case, it is not necessary to store and hold the protocol type PNO in each storage area 10a of the transmission history memory 10.

[0051]

As described above, in the inter-network connecting device of the present invention, the transmission history is stored and retained. Therefore, when transmitting data from the same source terminal to the same destination terminal, the same communication line is automatically selected and each transmission frame always reaches the destination terminal in the correct order, improving the reliability of data transmission. In addition, the number of retransmission occurrences is suppressed, and the communication processing efficiency of each network including terminals and the entire network system including the entire communication line can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an inter-network connection device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an entire network system in which the inter-network connecting device is incorporated.

FIG. 3 is a diagram showing stored contents of a communication history memory formed in the inter-network connecting device.

FIG. 4 is a diagram showing a format of a transmission frame transmitted between networks.

FIG. 5 is a flowchart showing the operation of the inter-network connection device.

[Explanation of symbols]

1a, 1b ... Network, 2a, 2b ... Transmission path, 3
a. 3b ... Terminals, 4a, 4b ... Inter-network connection device, 5 ... Communication line, 7a, 7b ... Line control section, 8 ... Network control section, 9 ... Frame memory, 10 ... Transmission history memory, 10a ... Storage area, 13 ... CPU, 15, 16
a, 16b ... Transmission frame, 17 ... Clock circuit

Claims (2)

[Claims] 1. A transmission line of a network from a transmission source terminal for transmitting data from a terminal of one network to a terminal of another network, which is inserted into a multiplexed communication line connecting between a plurality of networks. An inter-network connection device for inputting an output transmission frame and transmitting the input transmission frame to a transmission path of a network of a destination terminal via the communication line, has a plurality of storage areas, and stores each storage area. A transmission history memory that stores an address pair of a destination address of the destination terminal and a source address of the source terminal and a communication line in a region; and a detection unit that detects an address pair of a transmission frame input from the transmission path. A storage area detecting means for detecting a storage area in which the address pair detected by the detecting means is stored from within the transmission history memory And a communication line designating unit that designates a communication line stored in the storage region detected by the storage region detecting unit as a transmission line of the input transmission frame, and the storage region detecting unit detects the storage region. If not, a communication line for transmitting the transmission frame is separately designated, and a new registration means for writing the detected address pair and the designated communication line to a new storage area of the transmission history memory is provided. 2. A transmission line from a source terminal to a network transmission line for transmitting data from a terminal of one network to a terminal of another network, which is inserted into a multiplexed communication line connecting between a plurality of networks. An inter-network connection device for inputting an output transmission frame and transmitting the input transmission frame to a transmission path of a network of a destination terminal via the communication line, has a plurality of storage areas, and stores each storage area. In the area, an address pair of the destination address of the destination terminal and the source address of the source terminal, a transmission history memory that stores the protocol type of the transmission frame and the communication line, and an address pair of the transmission frame input from the transmission path And the detection means for detecting the protocol type, and the address pair and protocol type detected by this detection means A storage area detecting means for detecting the stored storage area from the transmission history memory, and a communication line stored in the storage area detected by the storage area detecting means is designated as a transmission line of the input transmission frame. And a communication line for transmitting a transmission frame when the storage area is not detected by the storage area detection means, and the detected address pair, the protocol type and the specified communication line are set as the transmission history. An inter-network connection device having new registration means for writing to a new storage area of a memory.