JP3361343B2 - Network connection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network connection device for connecting computer networks such as LAN using communication lines, and more particularly to a plurality of network connection devices including a bridge operation mode, a router operation mode and a bruta operation mode. The present invention relates to a network connection device having an operation mode.

[0002]

2. Description of the Related Art Generally, in a computer network such as a LAN (Local Area Network), various nodes such as workstations, telephones, facsimiles, printers and display devices are connected to a transmission line. Then, normally, various kinds of information exchange are carried out between the respective nodes connected to the transmission line of this one LAN. Also, a plurality of L
Information can be exchanged between nodes belonging to different LANs by connecting the ANs to each other via a public line or a dedicated line.

FIG. 9 shows, for example, two devices which are arranged at remote places from each other.
It is a schematic diagram which shows the schematic structure of one LAN. Each LAN1
Independent transmission lines 2a and 2b are provided on a and 1b, respectively. In addition, each transmission line 2 of each LAN 1a, 1b
a and 2b each have a plurality of nodes 3a (A1, A2,
, An), 3b (B1, B2, ..., Bm) are connected. The LANs 1a, 1 are connected to the transmission lines 2a, 2b through a WAN (wide area communication network) 4 as a communication line.
LAN connection devices 5a and 5b are connected as a network connection device for connecting the two terminals b to each other.

When each node 3a, 3b transmits data to the nodes 3b, 3a of the other LANs 1b, 1a to which it does not belong, in TCP / IP communication,
For example, when an IP datagram is included, the data is embedded in the Ethernet frame 6 shown in FIG.
a, 2b. In this Ethernet frame 6, a preamble PA is set at the beginning, a frame start delimiter SFD indicating the beginning of a valid frame is set at the second, and a destination address DA for specifying a destination node is set at the third.
Is set, the source address SA for identifying the source node is set fourth, and the type TYPE of the used protocol is set fifth. Then, it sets the header of the IP (Ethernet <br/> · Protocol) (IP header) is the actual data DATA to be transmitted thereafter are stored.
And finally, the frame check sequence (FC
S) is set.

LAN connecting devices 5a and 5b are shown in FIG.
It is configured like. LAN1a, each transmission path 2a 1b, the Ethernet Ne <br/> Ttofuremu 6 LAN interface 7a shown in FIG. 10 that is input from 2b (a), PA through 7b, SFD, as a data format FCS is removed Layer 1 designated by the control units 8a and 8b
Input to 0-12. That is, the control units 8a, 8
b has a function of guiding the data format input from the LAN interfaces 7a and 7b to the layers 10 to 12 according to the operation mode set by the operation mode setters 9a and 9b.

Further, the communication packets 14 and 14b shown in FIG. 10B or 10C input from the WAN 4 through the WAN interfaces 13a and 13b are set by the operation mode setters 9a and 9b. It has a function of leading to layers 10 to 12 according to the selected operation mode. Then, it is output to each transmission line 2a, 2b as an Ethernet frame 6 to which PA, SFD, FCS are added via the LAN interfaces 7a, 7b.

Here, a protocol between the LANs 1a and 1b will be described. When performing data transmission between the LANs 1a and 1b, the communication procedure (protocol)
Need to match. Generally, the LAN protocol is divided into seven layers from a lower layer to a higher layer as shown in FIG. The first layer is the protocol of the physical layer 10.
The second layer is a protocol of the data link layer 11, and is composed of a bridge unit, for example. The third layer is a protocol of the network layer 12, and is composed of, for example, a router unit. And the higher the hierarchy, the more complex the protocol.

Next, the operation modes set by the operation mode setting devices 9a and 9b will be described. This LAN connection device 5
In a and 5b, [Bridge operation mode], [Router operation mode], and [Bruta operation mode] can be selected as operation modes.

In the bridge operation mode, FIG.
As shown in (a), the LAN connecting device 5a on the transmitting side is
PA, SFD, and FCS are removed from the Ethernet frame 6 including the destination address DA and the source address SA shown in FIG. 10 (a) input from the own LAN 1a.
The data format is sent to the WAN 4 as the communication packet 14b shown in FIG. 10C via the data link layer 11 and the WAN interface 13a. The data link layer 11 sends the IP header as it is without interpreting the inside.

The LAN connecting device 5b on the receiving side is the WAN 4
To WAN interface 13b, data link layer 11
PA, SFD, FCS for communication packets received via
Is added, the original Ethernet frame 6 shown in FIG. 10A is assembled and sent to the transmission line 2b of the own LAN 1b.

That is, in the bridge operation mode, each node 3a. 1b is irrelevant regardless of the type of the protocol of the network layer adopted by each node 3a, 3b of each LAN 1a, 1b. Data can be transmitted and received between 3b.

Further, in the router operation mode, as shown in FIG.
As shown in 2 (b), the LAN connecting device 5a on the transmitting side
Creates a data format in which PA, SFD, and FCS are removed from the Ethernet frame 6 including the destination address DA and the source address SA shown in FIG. 12 interprets the inside of the IP header and determines whether to send it to the other LAN, and if necessary, from this data format, DA, SA, T
IP header and actual data are removed by removing each part of YPE
An IP datagram consisting of and is extracted and sent to the WAN 4 as a communication packet 14.

The LAN connecting device 5b on the receiving side is the WAN 4
From the communication packet 14 received via the network layer 12 from the PA, SFD, DA, SA, TYPE and FC.
By adding S, the original Ethernet frame 6 shown in FIG. 10A is assembled and sent to the transmission line 2b of the own LAN 1b. Note that the IP of the destination device is inside the IP header.
Since the address and the IP address of the transmission source device are stored, the destination address DA and the transmission source address SA can be restored by interpreting the inside of the IP header. That is, in this router operation mode, the protocols between the LANs must match.

Further, in the bruta operation mode,
As shown in FIG. 12C, usually two connection terminals are prepared, and if the transmission side or the reception side switches the connection terminals according to the operation mode of the other party, the operation modes of the transmission side and the reception side become one. Therefore, the bridge operation mode or router operation mode described above can be performed.

As described above, in the bruta operation mode, even if the protocols between the LANs do not match in the network layer 12, by switching the connection terminal, the data link layer 11 or the network layer 12 is used. Data transmission is possible.

As described above, data can be transmitted by the operator selecting the most suitable operation mode in accordance with the type of data to be transmitted and the state of the destination LAN.

[0017]

However, even in the LAN connecting device capable of switching the above-mentioned "bridge operation mode", "router operation mode" and "bruta operation mode", there are still the following problems to be improved. there were.

For example, when the LAN connecting device on the transmitting side is set to the router operation mode and the LAN connecting device on the receiving side is set to the bridge operating mode, the LAN on the receiving side is set.
The connection device uses the data link layer 11 as the uppermost layer.
Since only the communication packet that has passed through as can be received, the original Ethernet frame 6 shown in FIG. 10A cannot be reproduced from the communication packet 14 shown in FIG.

When the LAN connecting device on the transmitting side is set to the bridge operation mode and the LAN connecting device on the receiving side is set to the router operating mode, the LAN connecting device on the receiving side places the network layer 13 at the highest level. Since only the communication packet passed as a layer can be received, the communication packet 14b shown in FIG. 10C from the data link layer 11 cannot be taken.

Like the Bruta described in the prior art, 2
Even if the bruta does not have one connection terminal, each communication packet received at the receiving side can be Determine whether the packet is a communication packet that has come through a layer, and use the communication packet that can be handled in its own operation mode as a regular communication packet through the layer (layer) determined by its own operation mode. It is possible to make it possible.

Even in this case, two types of communication packets 6 and 14 are transmitted to the WAN 4 when the transmission side is set to the bruta operation mode. However, when the receiving side is set to the bridge operation mode or the router operation mode, unnecessary communication packets not used for reception are transmitted on the WAN 4, resulting in extra communication time and extra communication cost.

Therefore, in order to reliably transmit the data and use the communication line efficiently, different LAN 1a,
Each node 3a. When performing data transmission between 3b, the LAN connecting device on the sending side and the L on the receiving side
It is necessary to match the operation mode with the AN connection device.

However, when a large number of LANs are connected by using a public line or a private line, one LA
In some cases, N may need to perform data transmission with a plurality of LANs having different operation modes.

In this case, the connected LAN of the other party
It is necessary to match its own operation mode with the above operation mode each time. This work to match the operation mode of the other party may be changed by the other communication destination of the other party as well, so it is possible to confirm the operation mode of the other party, for example, by telephone each time. Very complicated because you need to set up.

Further, if such complicated switching work is frequently performed, there is a concern that data transmission may be performed in an incorrect operation mode due to a setting error.

The present invention has been made in view of the above circumstances, and the communication procedure and the like are originally determined by the standard and cannot be changed, but what is essentially what a WAN such as a public line or a private line does. Focusing on the fact that it is also good, add an identifier that identifies its own operation mode to each communication packet output from each layer (layer) corresponding to the set operation mode to the communication line, or add its own operation mode information. By transmitting the identification-only packet that includes the operation mode of the receiving side to the operation mode that is allowable for the operation mode of the transmitting side, and finally the operation modes of both can be made to match, A network connection device that does not need to switch the operation mode according to the operation mode, reduces the occurrence rate of data transmission errors, and greatly improves operability. An object of the present invention is to provide a.

[0027]

In order to solve the above problems, the present invention connects a plurality of computer networks, each of which is formed by connecting a plurality of nodes via a transmission path, with each other via a communication line. A network connection device having a plurality of layers including a data link layer and a network layer, and having a plurality of operation modes determined corresponding to the highest layer (layer) through which a communication packet passes, which is a transmission line. Identifier adding means for adding an identifier for specifying the set operation mode to the communication packet input from the communication layer and transmitted to the communication line through the layer corresponding to the set operation mode, and communication An identifier discriminating means for discriminating the identifier attached to the communication packet input from the line, and an operation mode permitted by the operation mode indicated by the identifier. An operation mode switching means for switching to de, dynamic switching the communication packet received from the communication line
Send to the transmission line via the layer corresponding to the operation mode
And means for

According to another aspect of the invention, an identification-dedicated packet transmitting means for transmitting an identification-dedicated packet incorporating information indicating a set operation mode to a communication line, and an identification-dedicated packet input from the communication line are provided. It is provided with an identification-only packet receiving means for receiving and an operation mode switching means for switching the operation mode to an operation mode permitted by the operation mode indicated by the operation mode information included in the received identification-only packet.

[0029]

With the network connecting device configured as described above, in the network connecting device on the transmitting side, the data input from the transmission line of the LAN to which the device is connected corresponds to the operation mode set for itself. It is sent as a communication packet to the communication line via the layer (layer).
In this case, the identifier adding means adds an identifier for identifying its own operation mode to the transmitted communication packet.

In the network connection device on the receiving side,
An identifier indicating the operation mode of the transmitting side is added to the communication packet input from the communication line. Then, the operation mode on the receiving side is automatically switched to the operation mode permitted by the operation mode specified by this identifier. Therefore, thereafter, the data transmission / reception can be normally executed between the transmission side LAN node and the reception side LAN node.

The allowable operating mode indicates that the transmitting side and the receiving side are in agreement with each other, and that there are combinations of operating modes that are acceptable even if they are not in agreement. For example, if the sender (other party) is in the bruta operation mode and the receiver (self) is in the router operation mode, the receiver directly receives the one of the two types of received communication packets that has passed through the network layer. Because it can be used, this combination is a non-matching but acceptable combination.

When data is transmitted and received between the nodes, the partner (the sender of this time) becomes the receiver in the next communication packet. Change to an allowable operating mode.
Therefore, both operation modes finally match.

Further, in another invention, for example, when the transmission side LAN and the reception side LAN are connected to each other through a communication line, an identification-dedicated packet in which information indicating its own operation mode is incorporated from the transmission side is transmitted via the communication line. Is transmitted to the receiving side.
Then, the operation mode on the receiving side is automatically switched to the operation mode permitted by the operation mode indicated by the packet information for identification. Therefore, similarly to the above-described invention, thereafter, data transmission / reception can be normally performed between the node of the transmission side LAN and the node of the reception side LAN.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a LAN connection device as a network connection device of the embodiment. Since the configuration of the entire computer network in which the LAN connection device 21 is incorporated is almost the same as the configuration of the computer network shown in FIG. 9, description thereof will be omitted.

In FIG. 1, each node 3a of the LAN 1a
When transmitting data from the node to another node 3b of the LAN 1b, for example, when including an IP datagram, the node 3a sends out the Ethernet frame 6 shown in FIG. 10A to the transmission line 2a, as described above. The Ethernet frame 6 output to the transmission line 2a is transmitted via the LAN interface 22 in the LAN connection device 21 to PA, SFD,
It is input to the data output control unit 23 as a data format with FCS removed. The operation mode set by the operation mode setting unit 24 is input to the data output control unit 23. The operation modes that can be set in the apparatus of this embodiment are the three types of "bridge operation mode", "router operation mode" and "bruta operation mode" described above.

When the operation mode set by the operation mode setting section 24 is the bridge operation mode, the data output control section 23 sends the input data format to the bridge section 26 constituting the data link layer 25. Further, when the operation mode is the router operation mode, the input data format is applied to the router unit 28 which constitutes the network layer 27.
Send to. Furthermore, the data output control unit 23, when the operation mode is the brouter operation mode, and interprets the data format entered IP datagram if it router 2
8 to the bridge unit 26 otherwise .
It

The bridge section 26 constituting the data link layer 25 sends the input data format as it is to the identifier adding section 29 as the communication packet 6a. On the other hand, the router unit 28 constituting the network layer 27 removes DA, SA, and TYPE from the input data format, creates a communication packet 14 called an IP datagram composed of an IP header and DATA, and creates an identifier adding unit. Two
9 is sent.

The operation mode currently set in the LAN connection device 21 is input from the operation mode setting section 24 to the identifier adding section 29. Then, the head of the communication packet 14b format identifier adding unit 29 shown in FIG. 10 that is input from the bridge portion 26 (c), FIG. 5
As shown in (a), an identifier 30 indicating the operation mode is added. For example, in the bridge operation mode, B is added at the beginning
The flag of (= [00] _H ) is added, and in the case of the router operation mode, the flag of R (= [02] _H ) is added at the beginning,
In the bruta operation mode, BR (= [0
1] _H ) flag is added. The communication packet 6a to which the identifier 30 is added is sent to the WAN 4 via the WAN interface 31.

Further, the identifier adding unit 29, at the beginning of the communication packet 14 of the format shown in FIG. 10B input from the router unit 28, as shown in FIG. Add. And the identifier 30
The communication packet 14a to which is added is the same as the other communication packet 6a through the WAN interface 31.
It is sent to N4.

On the contrary, from the WAN 4 to this LAN connection device 2
The communication packets 6a and 14a shown in FIG. 5 (a) or FIG. 5 (b), which have been input to the network 1, are input to the data input control unit 32 via the WAN interface 31.

The operation mode set in the operation mode setting section 24 is input to the data input control section 32.
The data input control unit 32 then receives the communication packets 6a, 14 input via the WAN interface 31.
The identifier 30 set at the beginning of a is read. Then, the operation mode of the LAN connecting device on the transmission side (other party) indicated by the read identifier 30 is compared with the operation mode set in the own operation mode setting unit 24, and if they do not match, the operation mode is switched in principle. An operation mode switching command is sent to the unit 33. The operation mode switching unit 33 switches the operation mode set in the operation mode setting unit 24 to the designated operation mode based on the switching command.

Further, when the operation mode of the other side (transmission side) indicated by the received communication packets 6a, 14a matches the operation mode of its own (reception side), the data input control section 32 receives each communication. The packets 6a and 14a are sent to the layers 25 and 27 designated by the operation mode set in the operation mode setting unit 24. That is, when the operation mode is the bridge operation mode, the received communication packet 6a is sent to the bridge unit 26. Further, the communication packet 14a received in the router operation mode is sent to the router unit 28. Further, the communication packets 6a and 14a received in the bruta operation mode are sent to the bridge unit 26 and the router unit 28, respectively.

The communication packet 6a shown in FIG. 5A is input to the LAN interface 22 via the data link layer 25 of the bridge section 26. Then, after the identifier 30 is removed by the LAN interface 22, PA, SFD,
The original Ethernet frame 6 shown in FIG. 10A to which the FCS is added is sent to the transmission line 2a of the LAN 1a.

Similarly, the communication packet 1 shown in FIG.
4a is an IP via the network layer 27 of the router unit 28.
The inside of the header is interpreted, DA, SA, and TYPE are added, and the result is input to the LAN interface 22. Then, after the identifier 30 is removed by the LAN interface 22, the original Ethernet frame 6 with PA, SFD, FCS is added, and the transmission line 2a of the LAN 1a is obtained.
Sent to.

FIG. 2 shows that the Ethernet frame 6 input from the LAN in the LAN connection device 21 shown in FIG.
It is a flowchart which shows the data output process which outputs to N4. L
When the Ethernet frame 6 is received from the AN transmission path (P1) and the operation mode is the bridge operation mode (P2), the received Ethernet frame 6 is shown in FIG.
The packet is converted into the communication packet 14b shown in (c) and passed through the bridge unit 26 (P3), the identifier 30 of B indicating the bridge operation mode is added (P4), and then sent to the WAN4 (P5).

When the operation mode is the router operation mode (P6), the Ethernet frame 6 is set as shown in FIG. 10 (b).
Is converted into the IP datagram shown in (1) and passed through the router unit 28 (P7), and the R identifier 3 indicating the router operation mode is displayed.
0 is added (P8), and then sent to WAN4 (P
5).

Further, if the operation mode is neither the bridge operation mode nor the router operation mode (P2, P6), since it is the bruta operation mode, the data format of the received Ethernet frame 6 is set to the data output control unit 23.
If it is an IP datagram (P9), it is passed through the router unit 28 (P10), an identifier BR indicating the bruta operation mode is added (P11), and otherwise.
The identifier BR is also added via the bridge unit 26 (P12) (P13), and then sent to the WAN4 (P5).

FIG. 3 is a flow chart showing a data input process for outputting the communication packets 6a and 14a inputted from the WAN 4 to the LAN in the LAN connection device 21 shown in FIG.
When the communication packets 6a and 14a to which the identifier 30 is added are received from the WAN 4 through the WAN interface 31 (Q1), the data input control unit 32 reads the identifier 30 attached to the communication packets 6a and 14a (Q2).
When the operation mode designated by the identifier 30 matches the own operation mode set in the own operation mode setting unit 24 (Q4), the communication packet 6 received as described above is transmitted.
a, layer 14 for which 14a is designated by the operation mode,
It is sent to 27 (Q5).

When the operation mode of the identifier 30 of the received communication packets 6a and 14a and the own operation mode do not match (Q4), each combination of the operation mode of the identifier 30 (other party) and the own operation mode. The processing according to is executed.

When the operation mode of the other party (identifier 30) is the bridge operation mode and the own operation mode is the bruta operation mode (Q6, Q7), the own operation mode is changed to the bridge operation mode which is the operation mode of the other party. Do (Q
8). Then, the received communication packet 14a is sent to the bridge unit 26 (Q9).

When the operation mode of the other party (identifier 30) is the bridge operation mode and the self operation mode is a router operation mode other than the bruta operation mode (Q6, Q
7), the line of WAN4 is cut off (Q10).

The reason for this is that the bridge is premised on communication between hosts having the same network address, whereas the router is premised on communication between hosts having different network addresses. This is because even if the communication packet is received, the communication packet is discarded as it is, so that the communication cost is not wasted.

In Q11 and Q12 of FIG. 4, when the operation mode of the other party (identifier 30) is the bruta operation mode and the own operation mode is the bridge operation mode, the operation mode of the other party is changed to the bridge operation mode. Then, the received communication packet 6a is sent to the bridge unit 26 (Q13). In the case of this combination, the own operation mode is not changed.

When the operation mode of the other party (identifier 30) is the bruta operation mode and the self operation mode is the router operation mode other than the bridge operation mode (Q11, Q12),
Change the operation mode of the other side to the router operation mode. Then, the received communication packet 14a is sent to the router unit 28 (Q14). Even in this combination, the operation mode of itself is not changed.

When the operation mode of the other side (identifier 30) is the router operation mode and the self operation mode is the bruta operation mode (Q15, Q16), the self operation mode is changed to the router operation mode which is the operation mode of the other side. Yes (Q1
7). Then, the received communication packet 14a is sent to the router unit 28 (Q18).

Furthermore, when the operation mode of the other party (identifier 30) is the router operation mode and the self operation mode is a bridge operation mode other than the bruta operation mode (Q15, Q
16) On the basis of the above-mentioned premise, the bridge discards the communication packet received from the router as it is, so the line is cut off (Q19).

Then, a series of data transmission processing is started between the nodes 3a and 3b in a state where the operation modes coincide or become the allowable operation mode. If the operation mode of the other party is not changed even though the operation mode of the other party does not match, the operation mode of the other party will be set when the next communication packet is transmitted from the self to the LAN of the other party. Is changed to match its own operation mode. Therefore, finally, the operation modes of the both agree with each other.

FIG. 6 is a diagram showing a correspondence relationship between the own operation mode before the start of transmission and the operation mode of the other side and the relationship between the operation modes after the start, and in the embodiment apparatus, this relationship is shown. The correspondence is stored in the data input control unit 32 of the LAN connection device 21 in the form of a table.

Then, when a series of data transmission processing is finally completed between the nodes 3a and 3b in a state where the operation modes match each other, the changed operation mode is returned to the operation mode before the change as a general rule. .

The LAN connection device 21 configured as described above
In this case, in the LAN connecting device on the receiving side, the data input control unit 32 determines the operation mode of the transmitting side (the other side) based on the identifier 30 attached to the received communication packets 6a and 14a, and the own operation is performed. When the mode and the operation mode of the other party do not match, the own operation mode and the operation mode of the other party match during the period of one round trip of data.

Therefore, the second communication packet 6a. When 14a is received, the operation modes are the same from the beginning, so that data can be transmitted normally. Therefore, after the second time, normal data transmission can be performed between the nodes 3a and 3b incorporated in different LANs.

Therefore, as in the conventional device, it is sure to confirm whether the operation mode matches the operation mode of the other party by, for example, a telephone, and if they do not match, the operation mode of the self is set to match. No need to switch. Therefore, since it is not necessary to change the operation mode of the other party each time the operation mode of the other party is changed, the operability can be greatly improved.

Also, since the combination of the other party (sending side) in the bruta operation mode and the self (receiving side) in the router operation mode or the bridge operation mode is finally resolved, it is not used by the receiving side. No communication packet is transmitted on the communication line. Therefore, the communication efficiency in the communication line can be improved and the communication cost can be reduced.

FIG. 8 is a block diagram showing a schematic configuration of a LAN connection device 34 as a network connection device according to another embodiment of the present invention. The same parts as those of the embodiment shown in FIG. 1 are designated by the same reference numerals, and detailed description of the overlapping parts will be omitted.

In this embodiment, the identifier adding section 29
Instead of, the identification packet generator 35 is incorporated.
The identification packet generator 35 includes an operation mode setting unit 24.
The operation mode identification communication packet 36 shown in FIG. 7 incorporating the operation mode set in step 1 is created. The operation mode identification communication packet 36 is provided with the identifier 30 indicating the current operation mode.

When the communication line is connected to the other side for the first time, the identification packet generating section 35 automatically transmits the operation mode identification communication packet 36 incorporating the information indicating the current operation mode of itself through the WAN interface 31. WAN4
Send to.

The data input control unit 32, which has received the operation mode identification communication packet 36 via the WAN interface 31, determines the operation mode of the other party (transmission side) from the identifier 30 of the operation mode identification communication packet 36. As described above, the operation mode of its own is changed according to the setting contents of the table shown in FIG. 6 stored in its storage unit.

Even in the LAN connecting device 34 having such a configuration, since the operation modes of the transmitting side and the receiving side are finally the same, it is possible to obtain substantially the same effect as that of the previous embodiment. Further, in this embodiment, since the operation mode identification communication packet 36 is transmitted and received only in the first round trip where LANs are connected to each other, the extra identifier 30 is not added to the normal communication packets 6 and 14, so that the data is transmitted. Transmission efficiency increases.

The present invention is not limited to the above embodiment. Although the Ethernet frame including the IP datagram has been described in the above-described embodiment, various modifications can be made according to the gist of the present invention. The same effect can be obtained in the above, and these are not excluded from the present invention.

[0071]

As described above, according to the network connection device of the present invention, its own operation mode is specified in each communication packet output from each layer corresponding to the set operation mode to the communication line. A packet for identification is added or an identification-only packet including its own operation mode information is transmitted. Therefore, the operation mode on the receiving side can be set to an operation mode that is acceptable to the operation mode on the transmitting side, and finally the operation modes on the receiving side and the transmitting side can be matched.

Therefore, it is not necessary to switch the operation mode of the user in accordance with the other party, the occurrence rate of data transmission error can be reduced, and the operability can be greatly improved. further,
The communication line can be used efficiently and the communication cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is a flow chart showing a data output operation of the apparatus of the embodiment,

FIG. 3 is a flow chart showing a data input operation of the embodiment apparatus,

FIG. 4 is a flowchart showing a data input operation of the apparatus of the embodiment,

FIG. 5 is a format diagram showing each communication packet used in the apparatus of the embodiment.

FIG. 6 is a diagram showing an operation mode switching destination between a transmitting side and a receiving side in the embodiment apparatus;

FIG. 7 is a format diagram showing an operation mode identifying communication packet used in a network connection device according to another embodiment of the present invention;

FIG. 8 is a block diagram showing a schematic configuration of the apparatus of the embodiment.

FIG. 9 is a diagram showing a system in which general LANs are connected to each other,

FIG. 10 is a format diagram showing a general communication packet,

FIG. 11 is a block diagram showing the configuration of a general LAN connection device,

FIG. 12 is a schematic diagram showing a data transmission operation in each operation mode of a general LAN connection device.

[Explanation of symbols]

1a, 1b ... LAN (computer network), 2
a, 2b ... Transmission line, 3a, 3b ... Node, 4 ... WAN
(Communication line), 6, 6a, 14, 14a ... Communication packet, 21, 34 ... LAN connection device (network connection device), 22 ... LAN interface, 23 ... Data output control unit, 24 ... Operation mode setting unit, 25 ... Data link layer, 26 ... Bridge unit, 27 ... Network layer, 28 ...
Router section, 29 ... Identifier adding section, 30 ... Identifier, 31 ...
WAN interface, 32 ... Data input control unit, 33
... operation mode switching unit, 35 ... identification packet generating unit, 36
... operation mode identification communication packet.

Claims (2)

(57) [Claims] 1. A plurality of computer networks (1a, 1b) each formed by connecting a plurality of nodes (3a, 3b) via a transmission line (2a, 2b) are connected via a communication line (4). Data link layer (25) and network layer (27)
A network connection device having a plurality of operation modes determined by corresponding to the highest layer (layer) through which a communication packet passes by incorporating a plurality of layers (layers) including Identifier adding means (29) for adding an identifier for specifying the set operation mode to a communication packet sent to the communication line through a layer corresponding to the operation mode being set, Identifier discriminating means (32) for discriminating an identifier attached to a communication packet input from a communication line, and an operation mode switching means (33) for switching the operation mode to an operation mode permitted by the operation mode indicated by the identifier , Input from the communication line
The transmitted communication packet according to the switched operation mode.
A network connection device comprising: means for sending to the transmission path via a layer . 2. A plurality of computer networks, each of which is formed by connecting a plurality of nodes via a transmission line, are connected via a communication line, and a plurality of layers including a data link layer and a network layer are provided. A network connection device that has a plurality of operation modes that are incorporated and are determined corresponding to the highest layer (layer) through which communication packets pass, and that is an identification-only packet that incorporates information indicating the set operation mode ( Dedicated packet transmitting means (35) for sending out 36) to the communication line, and identification dedicated packet receiving means (32) for receiving the identification dedicated packet input from the communication line
A network connection device comprising: and an operation mode switching means (33) for switching the operation mode to an operation mode permitted by the operation mode indicated by the operation mode information included in the received identification-only packet.