JP2746246B2 - Learning function table management method in LAN bridge device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a plurality of LANs (L
ocal Area Network. The present invention relates to a learning function table management method in a LAN bridge device that manages a learning function table provided in a bridge device that connects a local area network.

The learning function table in the present invention is provided for each LAN (each of a plurality of LANs connected to the bridge device in which the learning function table exists), and is connected to each LAN. A table that stores identification information of a terminal device (eg, a terminal number) and identification information (address) of a LAN where the terminal device is located (or a LAN having a route to the LAN where the terminal device is located) ( See Fig. 2 etc. The expression "terminal device address" in Fig. 2 etc. means information including the identification information of the terminal device and the identification information of the LAN).

[0003]

2. Description of the Related Art LANs have become increasingly popular, their use has been advanced, and communication systems for interconnecting a plurality of LANs have been increasing.

In such a communication system, a bridge device for connecting a plurality of LANs is required. Also,
In such a bridge device, in order to manage the location of the terminal device in the network of the communication system, the learning function table as described above is required.

FIGS. 2 (a) and 3 (a) show specific examples of the network configuration of such a communication system (as will be described later, these figures are used for describing an embodiment of the present invention). It is a figure).

FIG. 1 is a diagram showing a configuration of a bridge device for realizing one embodiment of the present invention described later.
The configuration of the bridge device in FIG. 1 is also applicable to a conventional bridge device except for the functions specific to the present invention in the source address determination unit 21 and the relay transmission unit 22.

That is, conventionally, a LAN bridge device is configured to include a learning function table existing for each LAN to be connected, an exchange / learning control unit, and a line connection unit existing for each LAN to be connected. I have. Each line connection unit is a part for performing line connection with each LAN. Each learning function table is a table for registering the address of each terminal device connected to each LAN as described above.
The exchange / learning function control unit is a part that absorbs a difference in protocol between LANs and registers an address in the learning function table. It should be noted that the number of LANs to be connected can be increased by adding line connection units.

Under the above network configuration,
When the terminal device communicates via the LAN, a destination address (DA.D) serving as a destination address is used.
source address and a source address (SA) which is a source address.
) is added to the head of the information to be communicated to form a frame, and the frame is transmitted.

The bridge device recognizes a source address in a frame transmitted from a certain terminal device, and registers the address of the terminal device in a learning function table of a corresponding LAN based on the recognition. Thus, “learning of the address of the terminal device” is realized.)

[0010] By such learning, the bridge device thereafter operates according to the address registered in the learning function table.
The LAN to which each terminal device belongs is identified.

That is, when the bridge device receives a frame, the destination address in the received frame is compared with the registered address in the learning function table for each LAN, and the registered address matching the destination address is compared. The frame is relayed and transmitted to the LAN holding the address.

For example, in a communication system having a network configuration shown in FIG.
It is assumed that N101 has received a “frame whose destination address is the address of the terminal device 109”. In this case, the bridge device 105 stores the learning function table for LAN 101 in the bridge device 105 and L
Referring to the learning function table for AN 102 (see FIG. 2B), the destination address and each registered address are compared, and the LAN in which the terminal device 109 is located is compared.
(Or a LAN that has a route to the LAN where the terminal device 109 is located). That is, in this example, since the address of the terminal device 109 is registered in the learning function table for the LAN 102, the bridge device 105 relays the frame to the LAN 102.

As described above, conventionally, in a LAN bridge device, a different L is provided by providing a learning function table having the above contents in the bridge device.
Communication between ANs (communication between terminal devices connected to different LANs) has been efficiently processed.

Here, in the learning function table management method in the conventional LAN bridge device, the registration of the address of a newly installed terminal device has been realized by performing the above-described learning.

By the way, a terminal device may move between LANs for some reason. As terminal devices have been miniaturized and portable terminal devices have become commercially available, the terminal devices have often been moved as necessary. In recent communication systems, not only wired communication media such as coaxial cables, twisted pair cables, and optical cables, but also wireless communication media have become available. Therefore, LA using wireless as a communication medium
N has also been put to practical use, and the opportunity to carry the terminal device has been further increased.
The number of cases where it is performed is increasing.

In such a case, when a terminal device existing in a certain LAN moves to another LAN, and when communication is performed with the terminal device after the movement, the contents of the learning function table in the bridge device are changed. If the terminal device remains as it is, the frame addressed to the terminal device will be guided to the LAN from which the terminal device has moved, and will not reach the LAN to which the terminal device has moved, resulting in communication failure. .

In the conventional learning function table management method in the LAN bridge device, the following methods have been adopted to cope with such a case.

Rewriting of the registered contents of the learning function table (rewriting reflecting the movement of the terminal device) is performed by a human manual operation.

A duration is defined for each entry in the learning function table, and registration of the address of the terminal device in the entry is deleted from the learning function table after a period of time during which there is no reference to the entry has elapsed. . Thus, after the registration of the terminal device is deleted,
Learning is performed again. Thereby, finally, the registration of the learning function table reflecting the movement of the terminal device is realized, and the communication becomes possible again.

[0020]

The above-mentioned conventional LAN
In the learning function table management method in the bridge device of the above, a problem that human labor is required in dealing with the occurrence of communication failure due to “movement of the terminal device between LANs” (the problem in the above-described method) )
There has been a problem that the communication disabled state continues while the "duration" elapses (problem in the above-described method).

Here, in order to solve the above-mentioned problem (the problem that communication becomes impossible when the terminal device moves from one LAN to another LAN), Japanese Patent Laid-Open No. 4-15 / 1990
In the invention described in Japanese Patent No. 4335 (a learning function table management method in a bridge device of a local area network) and the invention described in Japanese Patent Application Laid-Open No. 2-181545 (LAN bridge address management method), the learning is not performed. A solution has been shown in which, when a frame is transmitted to the bridge device from a different direction, the contents of the learning function table are immediately updated.

However, in these inventions, only the learning function table of the bridge device directly connected to the destination LAN of the terminal device is updated, and the learning function of the entire network (a network constituted by a plurality of LANs) is performed. There was a problem that the table was not updated.

Further, in order to update the learning function table of the entire network, it is necessary to notify each other of changes in the network configuration between the bridge devices. There is.

On the other hand, Japanese Patent Application Laid-Open No. 4-152733 discloses
A solution for monitoring an abnormal state of a network is disclosed by the invention (network management device and network monitoring device of an irregular communication network) described in Japanese Unexamined Patent Application Publication No. 2000-205,036. However, the present invention does not work without a management station for managing the network, and cannot be applied to a network without a management station.

Further, according to the invention (network address management method) described in Japanese Patent Application Laid-Open No. 1-177736, a solution for centrally managing the address management of a network is shown. However, the present invention cannot cope with a simple movement of a terminal device between LANs without a change in the address of the terminal device.

Further, a solution for reducing network traffic is disclosed by the invention (bridge device) described in Japanese Patent Application Laid-Open No. 4-48842. However, in the present invention, even when the duration has elapsed due to the movement of the terminal device, the relay transmission in the broadcast mode is not performed, so that the frame does not reach the destination of the terminal device. Therefore, it cannot be applied in an operation in which the terminal device moves.

In view of the above, it is an object of the present invention to eliminate the need to manually rewrite a learning function table even when a terminal device moves between different LANs, and to rewrite the learning function table as quickly as possible. (Elapsed time) is not required), efficient automatic updating of the contents of the learning function table of the LAN that needs to be updated is realized, and communication with the terminal device after the movement of the terminal device can be continued. It is an object of the present invention to provide a learning function table management method in a bridge device of a LAN.

[0028]

The learning function table management method in the LAN bridge device according to the present invention comprises a plurality of L tables.
Connect the AN, in the bridge device for LAN for managing the location of the terminal device by the learning function table provided for each LAN, when receiving the target frame transmitted from a certain terminal apparatus, the source in the subject frame address first determination determines whether or not it is registered in the learning function table corresponding to LAN that received the target frame, the learning function table when the first determination judgment result is not registered The source address in the target frame and the result of the first judgment
Source address determining means for performing a second determination to determine whether or not a source address in the target frame exists in any of the learning function tables corresponding to the LANs that do not receive the target frame if they are not registered And the determination result of the second determination by the source address determination means is
To the learning function table in terms of the learning function table source address in the target frame when it is present there have deleted the same address as the source address
Relays the target frame to the corresponding LAN, and there is a determination result of the second determination by the source address determining means
And relay transmission means for relaying the target frame to all LANs connected to the bridge device other than the LAN receiving the target frame when the target frame is not received.

[0029]

[0030]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a bridge device for implementing an embodiment of a learning function table management method in a LAN bridge device of the present invention.

This bridge device connects a plurality of LANs (LANs in which some terminal devices are located), and exchanges a plurality of learning function tables 1 corresponding to the respective LANs with each other.
It is configured to include a learning control unit 2 and a plurality of circuit connection units 3 corresponding to each LAN.

The exchange / learning control unit 2 includes a source address determination unit 21 and a relay transmission unit 22.

The learning function table management method in the LAN bridge device of the present embodiment is realized by applying some of such bridge devices to a network of a communication system having a plurality of LANs.

FIGS. 2A to 2C and FIGS. 3A to 3 A
(C) shows the LAN bridge device of this embodiment when a certain terminal device moves from one LAN to another LAN in such a network (a network including a plurality of LANs and some bridge devices). It is a figure for explaining operation of a learning function table management method. Note that the network configuration of the present embodiment, and eventually of the communication system to which the present invention is applied, is shown in FIG.
Needless to say, the configuration is not limited to the configuration shown in FIG.

First, FIGS. 2A to 2C are diagrams for explaining a state of a certain terminal device (terminal device 107) before moving. FIG. 2A is a diagram illustrating a network configuration before the terminal device 107 moves, and FIG.
07, the learning function table 1 in the bridge device 105 before the movement (the learning function table for LAN 101 and the LAN 1
FIG. 2 is a diagram showing the contents of a learning function table for the O.02.
(C) shows the bridge device 106 before the terminal device 107 moves.
Learning function table 1 (a learning function table for LAN 102, a learning function table for LAN 103,
FIG. 4 is a diagram showing the contents of a learning function table (for 104).

FIGS. 3A to 3C show the terminal device 1.
FIG. 7 is a diagram for explaining a state after the movement of the reference numeral 07. FIG.
3A is a diagram illustrating a network configuration after the terminal device 107 has moved, and FIG. 3B is a diagram illustrating a learning function table 1 (LAN1) in the bridge device 105 after the terminal device 107 has moved.
FIG. 3C shows the contents of the learning function table 1 (the learning function table for the LAN 102 and the LAN 1) in the bridge device 106 after the terminal device 107 moves.
FIG. 3 is a diagram showing the contents of a learning function table for L.03 and a learning function table for LAN 104).

As shown in FIGS. 2A and 3A, this network is composed of LANs 101, 102,
103 and 104, and bridge devices 105 and 1
06, terminal devices 107, 108, 109, and 11
0 is included.

FIG. 4 is a flowchart showing the processing of the learning function table management method (processing at the time of receiving the target frame) in the LAN bridge device of this embodiment. This processing includes a learning function table search step 401 and a source address (indicated by “SA” in FIG. 4) presence determination step 402.
Source address addition step 403, unsearched learning function table selection step 404, selection learning function table search step 405, source address existence determination step 406, all learning function table search end determination step 407, source address deletion Step 408,
Selection target learning function table corresponding LAN target frame relay transmission step 409 and target frame relay transmission step 41
It consists of 0.

Next, the L of the present embodiment thus constructed is
The operation of the learning function table management method in the AN bridge device will be described.

First, the general operation of the learning function table management method in the LAN bridge device of the present embodiment will be described with reference to FIGS.

Exchange / learning control unit 2 in a certain bridge device
When receiving a frame (referred to as “target frame”) from a certain terminal device, the following operation is performed (see FIG. 4).

First, the source address judging means 21 in the exchange / learning control unit 2 extracts the source address from the target frame, and receives the target frame from the LAN (a certain LA).
N, the learning function table 1 corresponding to the LAN when the bridge device receives the target frame) is searched (step 401), and the source address (source address in the target frame) exists in the learning function table 1. It is determined whether or not to perform (Step 402).

If the source address determination means 21 determines in step 402 that "the source address of the target frame exists in the learning function table 1", the operation of the present embodiment for the target frame ends. Thereafter, the terminal device performs the same processing as in the related art, and relays the target frame to the LAN indicated by the destination address in the target frame via the predetermined line connection unit 3.

On the other hand, when the source address determining means 21 determines in step 402 that "the source address of the target frame does not exist in the learning function table 1", the source address is added to the learning function table 1. (Step 403).

Next, the source address judging means 21 determines whether or not there is a registered address that matches the source address in the target frame by checking all the learning function tables 1 (in the LAN receiving the target frame, Except for the corresponding learning function table 1), the following ~
Search by the procedure shown in.

One non-searched one is selected from the learning function table 1 corresponding to a LAN other than the LAN that received the target frame (the LAN that does not receive the target frame) (step 404).

The learning function table 1 selected in step 404 is searched (step 405), and it is determined whether the source address (source address in the target frame) exists in the learning function table 1 (step 4).
06).

If it is determined in step 406 that the source address does not exist in the learning function table 1, it is determined whether all the learning function tables 1 have been searched (the search of all the learning function tables 1 has been completed). Or not)
Is determined (step 407).

If it is determined in step 407 that “all the learning function tables 1 have not been searched”,
Control is returned to step 404, and the next learning function table 1
Is selected to perform the processing and determination after step 405.

On the other hand, if it is determined in step 407 that “all the learning function tables 1 have already been searched”, the source address does not exist in all the learning function tables 1 (if the terminal device is newly It recognizes that it is an installed terminal device) and transfers control to the relay transmitting means 22 accordingly.

If it is determined in step 406 that “the source address exists in the learning function table 1”, it means that “the registered address matching the source address exists in any learning function table 1”. Is recognized, and control is passed to the relay transmitting means 22 with that. The registered address that matches the source address exists only in one learning function table 1 (one of all learning function tables 1 except the learning function table 1 corresponding to the LAN that has received the target frame). Therefore, there is no inconvenience even if the control is passed to the relay transmission means 22 without waiting for the determination in step 407.

As described above, the relay transmitting means 22 to which control has been passed from the source address determining means 21 transmits the learning function table 1 (the learning function selected in the immediately preceding step 404) in which a registered address corresponding to the source address exists. The source address is deleted from the table 1) (step 408), and the LA corresponding to the learning function table 1 is deleted.
The target frame is relay-transmitted to N (step 409).

Further, the relay transmitting means 22 to which control has been passed from the source address determining means 21 as described above relays the target frame to all LANs other than the LAN from which the target frame was received (step 410).

Since the above processing is performed recursively for each bridge device in the network to which this embodiment is applied, the automatic update of the learning function table 1 is similarly performed for all other bridge devices in the network. Done.

Second, FIG. 2 together with FIG. 1 and FIG.
(A)-(c) and FIGS. 3 (a)-(c),
A specific operation of the learning function table management method in the LAN bridge device of the present embodiment will be described.

When each of the terminal devices 107 to 110 communicates with each other in the network configuration shown in FIG. 2A, two learning function tables 1 in the bridge device 105 are used.
As shown in FIG. 2B, each of the terminal devices 107 to 110
The addresses of the terminal devices 107 to 110 are registered in the three learning function tables 1 in the bridge device 106 as shown in FIG.

Here, as shown in FIG. 3A, after the terminal device 107 moves from the LAN 101 to the LAN 103, the terminal device 107 transmits a frame (this frame is a target frame) to the terminal device 109. The specific operation of the present embodiment will be described with an example of the case.

When the exchange / learning control unit 2 in the bridge device 106 receives a frame from the terminal device 107 to the terminal device 109 as a target frame, it performs the following operation (see FIG. 4).

First, the source address judging means 21 in the exchange / learning control unit 2 takes out the "address of the terminal device 107" which is the source address in the target frame.
The learning function table 1 (the learning function table for the LAN 103) corresponding to the LAN 103 that has received the target frame is searched (step 401), and it is determined whether or not the source address exists in the learning function table for the LAN 103 (step 401). Step 402).

The source address determining means 21 determines in step 402 that "the source address does not exist in the learning function table for LAN 103" (see FIG. 2C), and the source address is shown in FIG. 3C. L as shown
Add to the learning function table for AN103 (step 4
03).

Next, the source address determining means 21
The learning function table 1 (the learning function table for the LAN 103 is a learning function corresponding to the LAN that has received the target frame) in all the learning function tables 1 in the bridge device 106 to which the self apparatus belongs. (It is excluded because it is table 1).

That is, the LAN that has received the target frame
LAN1 corresponding to LAN102 and LAN104 which are LANs (LANs that do not receive the target frame) other than
In the learning function table for 02 and the learning function table for LAN 104, one unsearched one is selected (step 40).
4) Retrieval of the selected learning function table 1 (the learning function table for LAN 102) (step 405),
It is determined whether the source address exists in the learning function table 1 (step 406).

In this case, in step 406, “the learning function table 1 (the learning function table for the LAN 102)
Is present in the source address ", and the control is passed to the relay transmitting means 22 together with the result of the determination.

The relay transmitting means 22 to which control has been passed from the source address determining means 21 deletes the source address from the learning function table for the LAN 102 (step 40).
8) LA corresponding to learning function table for LAN 102
Relay the target frame to N102 (step 40).
9).

As described above, the bridge device 106 is connected to the LAN 1
03, the bridge device 105 relays the target frame to the LAN 102 and transmits the target frame to the LAN 1
02.

The bridge device 105 that has received the target frame from the LAN 102 performs the same processing as that described above in the bridge device 106.

That is, in the case of this example, the address of the terminal device 107 (the source address in the target frame) is added to the learning function table for the LAN 102 in the bridge device 105, and the learning function table for the LAN 101 is used as the terminal device 107. Is deleted, and the target frame is relayed to the LAN 101.

As described above, as the terminal device 107 moves, the learning function table 1 is updated as shown in FIGS. 3B and 3C. The state after this update is a state after all the bridge devices 105 and 106 have learned the positional relationship between all the terminal devices 107 to 110,
Thereafter, the terminal device 107 is connected to all the other terminal devices 108 to 11.
If 0, communication can be continued.

As described above, in the learning function table management method in the LAN bridge device of the present embodiment, when the source address in the target frame is registered in any of the learning function tables 1, the learning function table management method is used. The LAN corresponding to the learning function table 1 in which the source address is not registered has a relay transmitting unit 22 for controlling so as not to relay the target frame .

In the above description of the network configuration (see FIGS. 2A and 3A), a topology in which no loop exists in the network is taken up, but in the case of a network configuration having a topology in which a loop exists. In addition, the present invention can be easily applied if the spanning tree method is used so that there is no logical loop.

[0072]

As described above, according to the present invention,
By providing the source address determination means and the relay transmission means as described above, even when a terminal device connected to one LAN moves to another LAN, it is not necessary to rewrite the learning function table by manual operation, As soon as possible (without elapse of "duration" in the prior art), the learning function table of the LAN that needs to be updated
Enables efficient automatic updating of the contents of the table, there is an effect that continues communication for the terminal device after the movement of the terminal device becomes possible.

In particular, by controlling so that the target frame is not relayed and transmitted to the LAN corresponding to the learning function table in which the source address in the target frame is not registered, only the LAN that needs to update the learning function table is controlled. There is an effect that the target frame is relay-transmitted, and the network traffic required for the above-described automatic update can be reduced. The reason that this is possible is that when a terminal device connected to a certain LAN moves to another LAN, the bridge device receives a frame transmitted from the moved terminal device. In the bridge device from the LAN corresponding to the learning function table in which the source address in the frame is not registered, the learning function table has already been learned so that the frame addressed to the terminal device is guided to the bridge device. This is because there is no need to update the learning function table.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a bridge device for realizing an embodiment of a learning function table management method in a LAN bridge device of the present invention.

FIG. 2 is a diagram for explaining a specific operation of an embodiment of a learning function table management method in the LAN bridge device of the present invention.

FIG. 3 is a diagram for explaining a specific operation of an embodiment of a learning function table management method in the LAN bridge device of the present invention.

FIG. 4 is a flowchart showing a process of an embodiment of a learning function table management method in the LAN bridge device of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 learning function table 2 exchange / learning control unit 3 line connection unit 21 source address determination unit 22 relay transmission unit 101, 102, 103, 104 LAN 105, 106 bridge device 107, 108, 109, 110 terminal device 401 search for learning function table Step 402 Source address existence determination step 403 Source address addition step 404 Unsearched learning function table selection step 405 Selection learning function table search step 406 Source address existence determination step 407 All learning function table search end determination step 408 Source address deletion step 409 Selection learning Function table compatible LAN target frame relay transmission step 410 Target frame relay transmission step

Claims (2)

(57) [Claims] When a target frame transmitted from a certain terminal device is received in a LAN bridge device that connects a plurality of LANs and manages the location of the terminal device according to a learning function table provided for each LAN. , the first determination determining whether the source address in the target frame is registered in the learning function table corresponding to LAN that received the target frame, the first determination judgment result is not registered Adding a source address in the target frame to the learning function table in a certain case , and a learning function corresponding to a LAN that does not receive the target frame when the determination result of the first determination is not registered source address determination performed <br/> the second determination determining whether the source address in the target frame into either a table group is present Stage and, the learned on deleting the source address determining means second identical address learning function table and the source address source address in the target frame when the judgment result is that there exists a determination by Function table
Relays the target frame to the LAN corresponding to the source address, and determines the result of the second determination by the source address determining means.
LAN that has received the target frame if it does not exist
All LANs connected to the bridge device other than
And a relay transmission means for relaying and transmitting the target frame. Wherein the learning function table management method in LAN bridge apparatus according to claim 1, characterized in that it is applied to the network in the case where no loop exists in the network of the communication system constituted by a plurality of LAN.