JPH05235945A - Bridge device and network construction method - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to connect networks with multiple data link protocols and to relay data frames. [Structure] The data flowing from the network becomes data that has not been subjected to protocol processing through the hardware interface means and the data link protocol processing means, and passes through other data link protocol processing means and hardware interface means through the relay means. It becomes the converted data. At this time, the data link protocol management means permits only the data link protocol processing means specified in the management item to operate. Further, the spanning tree protocol processing means automatically designates a management item.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bridge device and a network construction method for connecting networks having a plurality of data link protocols and relaying data frames.

[0002]

2. Description of the Related Art In recent years, international standardization of computer network communication by OSI is progressing, and a situation has arisen in which a conventional communication system and a standardized communication system are mixed. First, as a conventional technique, a bridge device that connects networks of different data link protocols when one data link protocol exists on one physical network will be described.

FIG. 6 shows an example of the configuration of the bridge device according to the above-mentioned conventional technique. 61 is a data link protocol A
Is used for the first physical network, 62 is the second physical network using the data link protocol B, and 63 and 64 are input terminals that meet the electrical and physical connection conditions of the connected physical network. The hardware interface means 63a for outputting the data is a first data link protocol processing means, which performs protocol processing on the data inputted from the relay means 67 (the data is adapted to the data format of the protocol A). ), Outputs to the physical network 61, and removes protocol processing from the data input from the physical network 61 (returns data of the format of protocol A to raw data),
It outputs to the relay means 65.

Reference numeral 64a denotes a second data link protocol processing means, which performs the same processing for the protocol B as the data link protocol processing means 63a. Relay means 55
Relays data between the data link protocol processing means 63a and 64a. The operation of the bridge device configured as described above has two kinds of cases of relaying from the network 61 to the network 62 and vice versa.

Network 61 to Network 62
When relaying to. The protocol A data (packet, electronic message) flowing from the physical network 61 is input to the data link protocol processing means 63 a via the hardware interface means 63. The data link protocol processing means 63a checks whether the data format is the protocol A, performs error processing such as discarding the data if there is a protocol error, and if there is no protocol error, performs the protocol processing from the protocol A format. The data is restored to the data that has not been processed and output to the relay means 65. This data is input to the data link protocol processing means 64a via the relay device 65. The data link protocol processing means 64a performs protocol processing on the data so as to match the data format of the protocol B, and outputs the data to the hardware interface 64.
The hardware interface 64 outputs the data converted into the protocol B to the network 62.

Network 62 to Network 61
When relaying to. The same operation is performed by following the reverse route. By the way, international standardization of computer network communication by OSI has brought about a situation in which a conventional communication method and a standardized communication method are mixed. As for the data link protocol communication method, a standardized method has come to be used in addition to the conventional method. Some of the standardized methods use almost the same hardware interface for transmitting and receiving electrical signals as the conventional technology, and it is considered to share the resources of the physical network used in the conventional technology. Be done.

Taking Ethernet as an example, in the conventional system and the system standardized by OSI, the OSI standard, such as the transmission procedure of electric signals flowing through the Ethernet cable, is used.
The specifications in the physical layer in the 7-layer model are almost the same. The substantial difference between these two methods is the difference in the frame header added to the beginning of the frame transmitted by the data link protocol, as shown in FIGS. 5 (a) and 5 (b). This difference is identified by the type field (TF) shown in FIG. 5A and the length field (LN) shown in FIG. 5B. This is because the type field (TF) of FIG. 5A is a field for indicating a higher-level protocol that should take over the data link protocol data frame, and is 2 according to the regulations.
Only values above 048 can be entered. On the other hand, FIG.
The length field (LN) in (b) is a field in which the frame length is expressed in octets, and since this is also the maximum frame length of 1500 octets according to the Ethernet physical layer standard, only a numerical value of 1500 or less can be entered. .. Therefore, even if the two types of frames mix and flow on a certain Ethernet cable, the frame of one data link protocol becomes a frame error in the other data link protocol, and the influence on mutual communication devices is minimal. Is.

Therefore, it is possible to share the same physical medium with a plurality of data link protocols, and it is desirable to do so in terms of saving resources. Therefore,
The following bridge device can be assumed when connecting networks in which a plurality of data link protocols are mixed on one physical network. FIG. 7A is a block diagram showing a configuration of an assumed bridge device.

Reference numerals 71 to 75 are the same as the components having the same names in FIG. 5, and only 75 is different. A relay means 75 has four input / output terminals and simply relays data input from one terminal to the other three terminals. The operation of the bridge device configured in this way is, for example,
As for the frame of protocol A input from the first network 71, the frame converted to protocol B is output to the first network 71, and
The protocol A frame and the protocol B-converted frame are output to the network 71 of FIG.

[0010]

However, according to the prior art, there is a problem in that a bridge device for connecting between networks in which a plurality of data link protocols are mixed on one physical network as described above has not been realized. there were. Further, as described in the above-mentioned conventional technique, when transmitting and receiving a frame using a plurality of data link protocols on one physical network, both protocols can coexist on the same physical medium. In this case, the following problems occur when trying to connect with the bridge device shown in FIG.

This problem will be described with reference to FIG. 8, 11, 12, 13, and 14 are physical networks that perform communication using two different data link protocols, and 21, 23 and 25 are communication devices that transmit and receive using one data link protocol A, Reference numerals 22, 24, and 26 are communication devices for transmitting and receiving using the other data link protocol B, and reference numerals 31, 32, and 33 are bridge devices shown in FIG.

Under such an environment, firstly, a problem of a loop in one network occurs. For example, the frame of the data link protocol A output from the communication device 21 on the physical network 12 is converted into the data link protocol B by the bridge device 31 so that the communication device 22 can also receive the frame. However, the frame loop is configured such that the bridge device 32 converts the data link protocol A and the bridge device 31 converts the data link protocol B again.

Secondly, a duplication problem occurs with respect to the relay destination network. For example, the frame similarly output from the device 21 is the bridge device 32 and the communication device 2
The data link protocols A and B are converted into two frames so that the frames 3 and 24 can also receive the data and transmitted to the physical network 13. Further, both frames are converted into two frames and transmitted to the physical network 14 so that the bridge device 33 can receive the frames and the communication devices 25 and 26 can also receive the frames. as a result,
The communication device 25 receives the same two frames of the data link protocol A, and the communication device 26 receives the same two frames of the data link protocol B in duplicate. If the number of data link protocols to be supported is two, such duplication will result in the power of 2 (the number of bridges to be relayed minus 1), resulting in a significant increase in network traffic.

[0014]

In order to solve the above-mentioned problems, a bridge device of the present invention is a bridge device for connecting between networks in which a plurality of data link protocols coexist and relaying a data frame. The interface means includes an interface section including the same number of data link protocol processing means as the number of protocols on the network, a relay means, and a data link protocol management means, and the hardware interface means electrically connects to a network to which the hardware is connected. Input / output conforming to physical connection conditions is performed, operation of the data link protocol processing means is controlled by the data link protocol management means, and protocol processing is removed for data input from the hardware interface means. The relay To the hardware interface means, and the relay means is connected to the data link protocol processing means to output one data. Data is relayed from the link protocol processing means to all other data link protocol processing means, and the data link protocol management means holds the type of protocol to be processed as a management item, and the operation of the data link protocol processing means. The management item controls the data link protocol processing means to specify only one main data link protocol for each interface unit and other complementary data link protocols for each network. Only one designated management interface Has two parties Eisu, the data link protocol management means is configured to allow operation of only the data link protocol processing unit that is specified in either of the two parties.

Further, the bridge device includes a spanning tree protocol processing means having a function of determining a designated port in the spanning tree protocol, a plurality of the present bridge devices are connected on the network, and each bridge device has all data. When the link protocol is supported, the spanning tree protocol processing means may be configured to specify the designated port obtained for each complementary data link protocol to the management designated interface.

In the network construction method of the present invention, the hardware interface means and the protocol on the network are used when the network is constructed by the bridge device which connects the networks having a plurality of data link protocols and relays the data. An interface unit consisting of the same number of data link protocol processing means,
The hardware interface means performs input / output adapted to the connected network and electrical / physical connection conditions, and the data link protocol processing means comprises the relay means and the data link protocol management means. The operation is controlled by the link protocol management means, the protocol processing is removed for the data input from the hardware interface means, and the data is output to the relay means, and the protocol is applied to the data input from the relay means. The data is processed and output to the hardware interface means, the relay means is connected to the data link protocol processing means, and relays data from one data link protocol processing means to all other data link protocol processing means, The data link protocol Management unit holds the type of the to be processed protocol as the management item, and controls the permission of operation of the data link protocol processing means, wherein the management item, to the data link protocol processing means,
The data link protocol management includes two main data link protocols, one of which is designated for each interface section, and a management designated interface, which is designated only for each of the other complementary data link protocols for each network. The means connects a plurality of networks by a bridge device configured to permit operation of only the data link protocol processing means specified by either of the two, and a plurality of bridge devices are connected on one network. In the case where the data link protocol management means is set, the data link protocol managing means sets the management item, and the data link protocol which is the main route on one network is determined as the main data link protocol of the network. Step and network of the first step In the succeeding interface part, the interface part supporting the main data link protocol of the network designates it as the main data link protocol of the interface part, and designates the other as the supplementary data link protocol. And, for each of the complementary data link protocols specified in the second step, a third step in which only one interface is designated as a management-designated interface in all interface parts that support it, and a first step
In the interface part connected to the network in step 1 above, which does not support the main data link protocol of the network, one of the interfaces that supports the complementary data link protocol of the other interface part Is designated as the main data link protocol of the interface section. The other is a complementary data link protocol, and the fourth step of designating the management-designated interface according to the third step, and the other interface part in the bridge device which does not support the main data link protocol of the network of the first step. If there is still one that supports the complementary data link protocol of, the third step and the fourth step are repeated, and the fifth step is performed until there is no more, and the above steps connect to one network. When the setting is completed for all the interface units that are present, if there is a network that has not been set, the sixth step of returning to the first step.

[0017]

The hardware interface means outputs the data flowing from the network to the respective data link protocol processing means in the interface section. Each data link protocol processing means removes the protocol processing only for the data of the compatible protocol and outputs the data to the relay means. The relay means distributes the input data to each data link protocol processing means. Each data link protocol processing means performs respective protocol processing and outputs to the network via the hardware interface means. However, the data link protocol management means permits only the data link protocol processing means designated as the main data link protocol or the management designated interface of the supplementary data link protocols. This allows each bridge device to communicate with the main data link protocol,
In principle, only the protocol conversion with the supplementary data link protocol designated by the management designated interface will be executed.

Further, the spanning tree protocol processing means automatically designates the management designated interface by utilizing the function of determining the designated port of the spanning tree.

[0019]

EXAMPLE A bridge device according to a first example of the present invention will be described. FIG. 1 shows the configuration of the bridge device.
Reference numerals 1 and 2 are first and second physical networks, and data link protocols are mixedly used.

Reference numerals 3 and 4 denote hardware interface means for inputting / outputting in conformity with electrical / physical connection conditions of the connected network, and 3a-3c are data link protocol processing means, which are input from the hardware interface 1. The protocol processing is removed from the generated data (the data in the format of protocol A is returned to the raw data) and output to the relay means 7, and the data input from the relay means 7 is subjected to the protocol processing. The data is output to the hardware interface 1 (matching the data format of the protocol A) and each has an enable terminal, and the enable / disable of the above operation is controlled by the enable signal input to the hardware interface 1.

Data link protocol processing means 4a to 4c are also similar to 3a to 3c. The number of data link protocol processing means is equal to the number of data link protocols used in the connected network. The relay means 5 includes all the data link protocol processing means 3a to 3c, 4a to 4 in the bridge device.
It has a plurality of input / output terminals to which c and the like are connected, and has a function of relaying data input from one terminal to another terminal.

Reference numeral 7 is an interface section for the network 1, which is composed of 1, 3a to 3c, and 8 is an interface section for the network 2, 2, 4a.
.About.4c, both of which can input and output for three types of data link protocols. In FIG. 1, both the interface units 7 and 8 have three data link protocol processing means, but this is not restrictive, and any number of data link protocol processing means may be provided. Further, the number of interfaces is not limited to two, but if three or more interfaces are provided, the same number of networks can be connected.

Reference numeral 6 is a data link protocol management means, which has a management register consisting of flag bits for setting predetermined management items, and controls whether the data link protocol processing means 3a-4a operate according to this flag bit. .. As the management items, the following three items are set for each interface unit of the bridge device. Main data link protocol, Complementary data link protocol,
There are three management designation interfaces (see FIG. 4).
The data link protocol management means allows the individual data link protocol processing means to operate when specified to, is prohibited to operate when specified to, and is allowed to operate when specified to. The contents and setting method of this management item will be described in detail later.

FIG. 3 shows an example of a network connected by the bridge device. However, terminal devices other than the bridge device are omitted. Reference numerals 11 to 16 denote separate and independent networks, and the frame data of the data link protocol A flows through 11. Four kinds of frame data of the data link protocols A, B, C, D flow in the field 12. Similarly, frame data of the types shown in the drawing also flow in 13 to 16.

Reference numerals 21 to 25 respectively denote the bridge device shown in FIG. 1. Reference numeral 21 denotes an interface section on the network 11 side having one data link protocol processing means for supporting the data link protocol A, and an interface section on the network 12 side. Has three data link protocol processing means for supporting the data link protocols A, B, and C. Similarly, 22 to 24 have the same number of data link protocol processing units that support the data link protocol shown in the figure.

FIG. 4 shows a setting example of the management items set in the data link protocol management means 6 of each bridge device. The operation of the bridge device and the network configured as above will be described. First, how to set the management items of the data link protocol management means 6 of each bridge device in the network configuration shown in FIG. 2 will be described. These management items are set in advance by manual setting or by communicating with other data link protocol managing means, and the following three items are set in the data link protocol processing means of each interface section. Main data link protocol. That is, one main data link protocol is designated in the interface section of each bridge device. The operation of the data link protocol processing means that processes the protocol specified by this is always enabled. Complementary data link protocol. That is, all the data link protocols other than the main data link protocol are designated as the supplementary data link protocol. In principle, the operation of the data link protocol processing means designated by the supplementary data link protocol is disabled. Management designated interface. That is, for one complementary data link protocol, the management designation interface is designated so that there is only one of the data link protocol processing means connected to the same network including other bridge devices. The data link protocol processing means designated by this is disabled and its operation is enabled.

Next, a method of setting the above management items will be described. These management items must be set in consideration of all the bridge devices connected to the network, rather than being set arbitrarily by each bridge device alone. This is because the problem of the frame loop and the problem of the frame duplication are caused by the existence of two or more bridge devices on the network. If there are two or more functions that convert or relay the same protocol on one physical network, frame loops and frame duplications will occur. Therefore, only one protocol conversion or relay function is available on one network. Only one should exist.

Therefore, the management items of the data link protocol management means are set for each network by the following procedure. (As an example, the setting example in the network 12 is described in parentheses. See FIG. 4.) STEP1. The data link protocol that serves as the main route on the network is defined as the main data link protocol for the network. (In the network 12, the data link protocol A is used. Note that there are two main data link protocols, the main data link protocol of the network here and the main data link protocol of the interface section described later, and the two do not necessarily match. .) STEP2. In the interface unit connected to the network of STEP 1, the interface unit supporting the main data link protocol of the network designates it as the main data link protocol of the interface unit, and designates the other as the supplementary data link protocol. .. (In the interface unit connected to the network 12, in the bridge device 21, the data link protocol A is the main data link protocol and the data link protocols B and C are the complementary data link protocols. In the bridge device 22, A is the main and C is the main data link protocol. In addition, it is undecided because the bridge device 23 does not support A. In the bridge device 24, A is the main, and B and D are the complements.) STEP3. For each of the complementary data link protocols specified in STEP2, only one is specified as the management-specified interface in all the interface parts that support it. (For supplementary data link protocol B, only one of the bridge devices 21 and 24 supporting it is arbitrarily designated as the management designation interface. Similarly, for C, only 22 of 21 and 22 are supported. Similarly, only 24 of D are designated as the management designation interface.) STEP4. The interface part connected to the network of STEP1 that does not support the main data link protocol of the network is one of the interfaces that support the complementary data link protocol of other interface parts. To
It is designated as the main data link protocol of the interface section. Others are supplementary data link protocols, and S
The management designation interface is designated according to TEP3. (In the bridge device 23, B, C, and D are complementary data link protocols of the interface part of another bridge device, so B among them is the main data link protocol of the interface part of the bridge device 23. Other C , D are the supplementary data link protocols, and the management designation interface has already been designated for both C and D, so there is no need to designate them here.) STEP5. If there is still a bridge device that does not support the main data link protocol of the network and that supports the complementary data link protocol of the other interface section, repeat STEP 3 and STEP 4 until they disappear. (Network 12
Does not remain in. ) STEP6. When the setting is completed for all the interface units connected to one network as described above, the other networks are similarly set by STEPs 1 to 5, and are set for all the networks.
(After the setting of the network 12, the other networks 11, 13, 14, and 15 are also STEP 1
The same setting is made according to 5 In the network of FIG. 3 in which the management items are set as described above, the flow of frame data will be described with reference to FIG.

In FIG. 4, 1 indicates that it is designated, 0 indicates that it is not designated, and each data link protocol processing means is a main data link protocol or a complementary data link protocol and a management designation interface. The operation is permitted by the data link protocol management means only when specified to. For example, if frame data of data link protocol A flows from a terminal device (not shown) in the network 12, this data is transmitted from A to B by the bridge device 21.
Then, the bridge device 22 converts the data from A to C, the bridge device 24 converts the data from A to D, and outputs the data to the network 12. At this point, the network 12 has A, B,
Four types of data of C and D flow one by one. Further, these data are converted from A to A by the bridge device 21 and output to the network 11, converted from A to B and C by the bridge device 22 and output to the network 13, and from the B to C by the bridge device 23. Is converted to A to D by the bridge device 24 and output to the network 15.
Finally, the bridge device 25 converts C into C and D and outputs the converted data to the network 15. Also, for example,
If frame data of data link protocol A flows from a terminal device (not shown) in the network 11, this data is converted from A to A and B by the bridge device 21 and output to the network 12. These data are converted from A to C by the bridge device 22 and from A to D by the bridge device 24, and are converted to the network 1
2 is output. At this point, the network 12
Data of four types A, B, C, and D are present one by one, and the same operation as in the previous example is performed for the networks 13 to 16.

As described above, the data link protocol management means gives the permission or prohibition of the operation of each data link protocol processing means according to the management item. The individual data link protocol processing means are the main data link protocol,
Alternatively, the operation is permitted by the data link protocol management means only when the supplementary data link protocol and the management designation interface are designated. As a result, conversion between the main data link protocol and the complementary data link protocol is performed only by the data link protocol management designated interface which is designated only one on the network. Therefore, since there is no interface of the bridge device that reconverts the protocol once converted to the complementary data link protocol to another data link protocol, a loop does not occur and one frame of each data link protocol flows. Be done. Therefore, frames do not overlap when relaying between networks.

The second embodiment of the present invention will be described below. FIG. 2 shows the configuration of the bridge device. The components 1 to 8 are the same as those in FIG. 1 in the first embodiment, and only 9 is different. However, for simplification, the number of interfaces and the number of data link protocols to be managed are 2. Reference numeral 9 denotes a spanning tree protocol processing means, which uses the data link protocol A and communicates with the spanning tree protocol processing means of another bridge device on the networks 1 and 2 via the data link protocol processing means 3a and 4a. Communicate.

The operation of the bridge device configured as described above will be described. The network in which this bridge device is used is premised on the following points. (1) Each bridge device connected to the network has a spanning tree protocol processing means. (2) All bridge devices must support the data link protocol used in the network.

In the bridge device of this embodiment in such an environment, the spanning tree protocol processing means 9 is used for designating the management designated interface. That is, the spanning tree protocol processing means 9 uses the spanning tree protocol (for this, IEEE80
2.1d / D9. ), Only the function that determines the designated port by communicating with other bridge devices on the network is used. As for the designated port, when all the devices support the spanning tree protocol on one network, only one of the devices is determined as the designated port.
Therefore, if the bridge device to be the designated port is designated as the management designated interface of the supplementary data link protocol, only one can be designated automatically on the network.

Therefore, the spanning tree protocol processing means 9 periodically sends the data link protocol processing means 3 to the data link protocol processing means 3.
The designated port is determined by communicating with the spanning tree protocol processing means of another bridge device on the networks 1 and 2 via a and 4a. The spanning tree protocol processing means 9 notifies this designated port to the data link protocol management means, and the data link protocol management means sets the management designated interface of the complementary data link protocol.

Therefore, the procedure for setting the management items of the data link protocol management means 6 in this embodiment is simplified as follows. 1. The main data link protocol is
Since the interface of each bridge device supports all data link protocols, it can be uniquely specified in advance in each network. Here, the data link protocol used by the spanning tree protocol processing means of each bridge device is designated as the main data link protocol of the network. This is because the spanning tree protocol processing means of each bridge device facilitates communication, and communication is guaranteed between the bridge devices.

Therefore, this main data link protocol is the main data link protocol of the interface of each bridge device, and the other data link protocols are the complementary data link protocols. 2. The data link protocol management designated interface of each complementary data link protocol of the network is automatically assigned to the designated port determined by the spanning tree as described above.

As described above, according to this embodiment, the setting of the management items from STEP 1 to STEP 6 in the first embodiment can be automated.

[0038]

As described above, according to the present invention, even if a plurality of data link protocols are mixed on one physical network, there is an effect that they can be connected by a bridge device. Moreover, there is an effect that a frame loop does not occur even if a plurality of bridge devices are connected to one network, and an effect that a frame does not overlap even if a plurality of networks are sequentially connected by the bridge device. is there.

Further, under a special environment in which each of a plurality of bridge devices on one network supports all data link protocols, by providing a spanning tree protocol processing means, it is possible to easily set management items. Therefore, there is an effect that it is possible to dynamically deal with the change of the network topology due to the failure of the network device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a bridge device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a bridge device according to a second embodiment of the present invention.

FIG. 3 shows a bridge device according to an embodiment of the present invention.
It is a figure which shows the example of a connection which connected the some network.

FIG. 4 shows a setting example of management items set in a data link protocol management means of each bridge device of FIG. 3 in the embodiment.

FIG. 5 is a diagram showing formats of a conventional Ethernet frame and a standardized Ethernet frame.

FIG. 6 is a block diagram showing a configuration of a bridge device in a conventional technique.

FIG. 7 is a block diagram showing a configuration of a bridge device assumed when expanding the bridge device in the conventional technique.

8 is a diagram showing a connection example in which a plurality of networks are connected by the bridge device of FIG.

[Explanation of symbols]

 1, 2 First and second physical networks 3, 4 Hardware interface means, 3a to 3c Data link protocol processing means 4a to 4c Data link protocol processing means 5 Relay means 6 Data link protocol management means 7, 8 Interface section

Claims (3)

[Claims] 1. A bridge device for connecting data networks in which a plurality of data link protocols coexist and relaying data frames, comprising a hardware interface means and the same number of data link protocol processing means as the number of protocols on the network. An interface unit, a relay unit, and a data link protocol management unit are provided, and the hardware interface unit performs input / output conforming to a connected network and electrical / physical connection conditions, and the data link protocol processing unit. The operation is controlled by the data link protocol management means, the protocol processing is removed for the data input from the hardware interface means, the data is output to the relay means, and the data input from the relay means is output. For Protocol processing is performed and output to the hardware interface means, and the relay means is connected to the data link protocol processing means and relays data from one data link protocol processing means to all other data link protocol processing means. The data link protocol management means holds the type of protocol to be processed as a management item, controls whether the operation of the data link protocol processing means is permitted, and the management item is for the data link protocol processing means. A main data link protocol that is designated only one for each interface section, and a management designated interface that is designated only one for each complementary data link protocol for each other network. The protocol management means is A bridge device, which permits only the data link protocol processing means designated by either of the two. 2. The bridging device comprises a spanning tree protocol processing means having a function of determining a designated port in a spanning tree protocol, a plurality of the bridging devices are connected on a network, and each bridging device has all data. The bridge device according to claim 1, wherein, when the link protocol is supported, the spanning tree protocol processing means designates the designated port obtained for each complementary data link protocol to the management designated interface. 3. A hardware interface means and a data link protocol processing means of the same number as the number of protocols on the network when a network is constructed by a bridge device which connects between networks having a plurality of data link protocols and relays data. And a data link protocol management means, wherein the hardware interface means performs input / output matching the connected network and electrical / physical connection conditions, and the data link protocol The operation of the processing means is controlled by the data link protocol management means, the protocol processing is removed for the data input from the hardware interface means, the data is output to the relay means, and the data is input from the relay means. De Data processing, and outputs to the hardware interface means. The relay means is connected to the data link protocol processing means, and one data link protocol processing means to all other data link protocol processing. Relaying data to the means, the data link protocol management means holds the type of protocol to be processed as a management item, controls the permission or prohibition of operation of the data link protocol processing means, the management item is the data For the link protocol processing means, there are two main data link protocols, one is designated for each interface part and the other is a management designated interface that is designated only for each complementary data link protocol for each network. Having the data link protocol The network management unit connects a plurality of networks by a bridge device configured to permit the operation of only the data link protocol processing unit designated by either of the two, and connects a plurality of bridge devices on one network. A method for setting the management items of the data link protocol management means when a data link protocol is connected, wherein the data link protocol serving as the main route on one network is determined as the main data link protocol for that network. In the step 1 and the interface part connected to the network in the first step, the interface part supporting the main data link protocol of the network is
It is supported for the second step of designating it as the main data link protocol of the interface part and for designating the rest as the supplementary data link protocol, and for the supplementary data link protocol designated in the second step. The third step of designating only one management interface in all the interface parts, and the interface part that is connected to the network in the first step and does not support the main data link protocol of the network. Specifies one of the other interface units supporting the complementary data link protocol as the main data link protocol of the interface unit, if any.
The other is a complementary data link protocol, and a fourth step of designating a management designated interface according to the third step, and another interface part in the bridge device which does not support the main data link protocol of the network of the first step. If there is still one that supports the complementary data link protocol, repeat the third and fourth steps until the fifth step is completed, And a sixth step of returning to the first step if there is a network that has not been set when the setting is completed for all the interface units that are present.