JPH08335948A - LAN and LAN relay device - Google Patents

Abstract

(57) [Abstract] [Purpose] A LAN in which wireless LAN terminals and wired LAN terminals coexist is constructed without using a plurality of wired transmission paths and without generating a large number of unnecessary frames, and also for moving wireless LAN terminals. Make it possible to deal with it appropriately. When transmitting a wireless frame from the wireless LAN terminal 10a, "0" is set in the loop prevention bit, and the relay device 1
When transmitting a wireless frame from 2a, "1" is set. When the loop prevention bit is set to "1", the relay device 12b regards it as a radio frame from the relay device 12a and discards it. Since the loop prevention bit is used only in the wireless part, the configuration of the wired frame is the same as that of the existing wired LAN frame.
Besides, it is not necessary to provide a wired transmission path. Since the loop prevention bit is used, generation of many unnecessary frames can be prevented. Since each terminal is managed by using the table in each of the relay devices 12a to 12c, the wired LAN terminal 10
It can be suitably dealt with when a moves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN (Local Area N) having a wireless LAN terminal, a wired LAN terminal and a relay device.
etwork) and a LAN relay device used in this LAN.

[0002]

2. Description of the Related Art FIG. 7 shows an example of the structure of a wireless LAN. The LAN shown in this figure generally includes a plurality of LAN terminals 10, relay devices 12 each having a unique wireless communicable range (cell), and a relay line 14 connecting the relay devices 12. In this figure, two relay devices 12a and 12b are shown, one of which (12a) is the cell 100a and the other one (12a).
In b), the cell 100b is set as its wireless communicable range.

Each relay device 12 has a functional configuration as shown in FIG. 8, for example. As shown in this figure, the relay device 12 executes a wireless device 16 for performing wireless communication with the wireless LAN terminal 10, a wired LAN interface 18 for connection with the relay line 14, and processing related to relay. It comprises a CPU 20, a ROM 22 for storing various programs executed by the CPU 20 and parameters therefor, and a RAM 24 used as a work area of the CPU 20. The relay device 12 is
For example, it can be realized as a MAC (Media Access Control) bridge or a buffer repeater.

The wireless communication in the wireless LAN shown in FIG. 7 is executed using the wireless frame shown in FIG. The radio frame shown in this figure includes a radio frame header and data (payload). Of these, the radio frame header includes a call name code, a cell ID, a controller radio frame length code, and an HCS.
(CRC16) has a structure in which a wireless preamble and a frame synchronization code are added to the head. On the other hand, the data has an indefinite length, and can have the same configuration as a wired LAN frame, for example. In FIG. 9, specifically, I
CSMA / CD type L specified in EEE802.3
It adopts a structure conforming to AN (Ethernet in a narrow sense). In this case, the data (payload) is the destination MAC
The address, the source MAC address, the packet length code, the data, and the PCS (CRC32) will be included. In this way, the part from the call name code to the radio frame length code is protected by the CRC16, and the payload is CRC32.
It is possible to increase the probability of error detection in each of the radio frame header and the payload by protecting the. When the “data” in the wireless frame has the same structure as the wired LAN frame, it is only necessary to add / delete the wireless frame header in the relay device 12.
A wired LAN terminal can be directly connected to the relay line 14. That is, it becomes possible to perform communication between the wired LAN terminal and the wireless LAN terminal 10 via the relay device 12.

In the system shown in FIG. 7, the wireless LAN terminals 10 existing in the same cell 100 can directly perform wireless communication, and the wireless LAN terminals 10 belonging to different cells communicate with each other by the relay device 12. And relay line 1
It is possible to communicate via the communication port 4. In the latter case,
For example, when performing communication from the wireless LAN terminal 10a belonging to the cell 100a to the wireless LAN terminal 10b belonging to the cell 100b, the wireless frame transmitted from the wireless LAN terminal 10a is received by the relay device 12a, and the relay device 12a A "data" portion or the like is extracted from this wireless frame and transmitted to the trunk line 14. Destination wireless L
The relay device 12b of the cell 100b to which the AN terminal 10b belongs
Attaches a wireless frame header to the data received via the relay line 14 and then wirelessly transmits this. The destination wireless LAN terminal 10b receives this wireless frame.

Such a system configuration can be used in a so-called medium speed wireless LAN. In addition, this system has an advantage that the wired LAN terminal and the wireless LAN terminal 10 can be allowed to coexist on a single relay line 14. However, in this system, when the wireless LAN terminal 10 moves from the current cell 100 to another cell 100 during communication via the relay device 12, it may be impossible to maintain a communication line. There's a problem. That is, when the moving speed of the wireless LAN terminal 10 is low, and therefore, for example, when it takes more than a predetermined time to move from the cell 100a to the cell 100b, as a result of the incommunicable state continuing during the movement, the line connection is established. You will be disconnected.

In order to solve such a problem, the cells 100a and 100b may be arranged so that the cells 100a and 100b shown in FIG. 7, for example, overlap. By doing so, the connection can be continuously maintained via the relay device 12 regardless of the moving speed of the wireless LAN terminal 10. On the other hand, the following problems occur in this cell arrangement.

In a system in which cells are arranged such that cells 100a and 100b partially overlap each other, for example, as shown in FIG. 10, cells 100a and 100b are arranged.
The relay devices 12a and 12b both exist in the overlapping area of
Moreover, the wireless LAN terminals 10a and 10b are located outside this overlapping area.
May be located.

In this case, assuming that the relay devices 12a and 12b are configured as a conventionally known MAC bridge, the relay device 12a is configured such that the wireless LAN terminal 10b, which is a communication partner of the wireless LAN terminal 10a, communicates with the relay device 12a. Since it is located in a possible area, the wireless LAN terminal 10
It is determined that the wireless communication terminal a and the wireless LAN terminal 10b can directly communicate with each other and therefore it is not necessary to relay the wireless frame. The relay device 12b also makes a similar determination.
Therefore, for example, the wireless frame transmitted from the wireless LAN terminal 10a is not relayed to the wireless LAN terminal 10b.

It is assumed that the relay devices 12a and 12b are configured as a conventionally known buffer repeater, that is, a device for transmitting the received radio frame onto the relay line 14. In this case, for example, the wireless frame transmitted from the wireless LAN terminal 10a is first received by the relay device 12a, and the portion such as "data" is transmitted to the relay line 14. The relay device 12b, which has received this data via the relay line 14, adds a wireless frame header to this data and wirelessly transmits it. This wireless frame is a wireless LAN
In addition to being received by the terminal 10b, it is also received by the relay device 12a. Then, the relay device 12a takes out a portion such as "data" from this wireless frame and sends it to the relay line 14. Therefore, the relay device 12a and the relay device 1
Since an infinite transmission loop is formed between 2b, normal communication cannot be executed between the wireless LAN terminal 10a and the wireless LAN terminal 10b.

The applicant of the present application has already proposed a means for solving such a problem (Japanese Patent Application No. 5-275580).
issue). That is, the wireless frame transmitted and received between the wireless LAN terminal 10 and the relay device 12 is configured as shown in FIG. 11, and the relay frame transmitted by the relay line 14 is configured as shown in FIG. Such a problem can be avoided. A feature of these radio frames and relay frames is that a new variable RTT is added.
Since L is included, it is possible to detect how many relay devices 12 the frame has passed through so far.

FIGS. 13 and 14 show the flow of control using the RTTL in the procedure executed by each relay device 12. The procedure shown in these figures is stored as a program in the ROM 22 shown in FIG. 8 and is executed by the CPU 20.

In the prior proposal, for example, the wireless L shown in FIG.
When attempting to communicate from the AN terminal 10a to the wireless LAN terminal 10b, the wireless LAN terminal 10a sends the variable RTTL when transmitting the wireless frame shown in FIG.
Is set to 0. When the wireless frame transmitted from the wireless LAN terminal 10a is received by the relay device 12a (200 in FIG. 13), the relay device 12a determines whether the value of the variable RTTL included in the received wireless frame is less than 2. It is determined (202). At this point RTTL
Since = 0, the condition of RTTL <2 is satisfied. In this case, the relay device 12a transmits the received wireless frame to FIG.
Is converted into a relay frame having the configuration shown in (204), and the obtained relay frame is transmitted to the relay line 14 (20).
6). At that time, the relay device 12a adds 1 to the RTTL (208).

The relay frame transmitted on the relay line 14 is received by another relay device, for example, 12b (see FIG. 1).
4, 210). The relay device 12b converts the received relay frame into a wireless frame having the configuration shown in FIG.
2) The obtained wireless frame is wirelessly transmitted (21
4). At that time, the relay device 12b adds 1 to the variable RTTL (216). Therefore, at this point, the variable RTT
The value of L is 2.

This wireless frame is received not only by the wireless LAN terminal 10b in the cell 100b, but also by the relay device 12a (20).
0). At this point, RTTL = 2, so step 2
The determination condition of 02 is not satisfied. In this case, the relay device 12
Since a has already been relayed twice by the relay device 12, a regards this frame as a frame that should not be relayed, and discards the received wireless frame (218).

Therefore, in the above-mentioned proposal, the wireless LAN terminal 10 is arranged even under the arrangement as shown in FIG.
a between the wireless LAN terminal 10b and the relay devices 12a and 12a
It becomes possible to communicate via 2b. The transmission path that can occur in that case is, as shown in FIG.
(1) From the wireless LAN terminal 10a to the relay device 12a, the relay line 14, and the relay device 12b in this order, the wireless LAN terminal 1
0b and (2) a route from the wireless LAN terminal 10a to the wireless LAN terminal 10b through the relay device 12b, the relay line 14 and the relay device 12a in this order.
Therefore, with regard to the arrangement as shown in FIG. 10, relay transmission can be suitably performed without causing confusion in wireless and wired transmission and without causing an infinite frame transmission loop or the like. Also, cells 100a and 1
The communication performance equivalent to that of the cell 100a and the cell 100b integrated, that is, the equivalent expansion of the cell, can be realized by only overlapping a part of 00b. Also, FIG.
The radio frame shown in FIG. 1 can be realized only by inserting the RTTL into the radio frame shown in FIG.
The relay frame shown in FIG. 12 can be realized only by inserting the RTTL into a wired LAN frame compliant with Ethernet or IEEE802.3. In this case, the relay line header may have the same content as the header in the wired LAN frame.

[0017]

However, in the configuration previously proposed by the applicant of the present application, the trunk line frame transmitted by the trunk line 14 includes the variable RTTL required for relaying between wired and wireless. That is, it has a configuration different from that of a frame in a normal wired LAN. Therefore, in the previous proposal, a normal wired LAN is used.
The terminal cannot be connected to the trunk line 14 as it is, and the configuration or function of the wired LAN terminal to be connected is changed, or the LAN connection using the wireless wired bridge as shown in FIG. 16 is made. Need to use.

The wireless LAN shown in FIG. 16 has a configuration in which three relay devices 12a to 12c are connected to a relay line 14. Further, the relay device 12c is provided in the overlapping portion of the cell 100a of the relay device 12a and the cell 100b of the relay device 12b. Under such a configuration, the cell 100
a, the cell 100b functions as an equivalently expanded single cell, that is, an expanded cell. Such a wireless LAN
Is connected to a wired LAN, a wireless wired bridge 26 is provided at any place in the expansion cell. The wireless wired bridge 26 includes the relay devices 12b and 12c and the wireless L.
The wireless frame from the AN terminal 10b is received, and this is removed from the normal wired LAN frame, for example, the relay frame shown in FIG.
The frame is converted into a frame conforming to EEE802.3 or Ethernet, and this frame is sent out on the transmission line 28 related to the wired LAN. The wired LAN terminal 30 receives the wired LAN frame from the wireless wired bridge 26 via the transmission line 28. With such a configuration, without changing the configuration or function of the wired LAN terminal 30 and using the conventional wired LAN as it is,
It is possible to realize an integrated LAN in which the wireless LAN terminal 10 and the wired LAN terminal 30 are mixed.

However, as described above, the wireless wired bridge 26
In addition to the problem that two systems of wired transmission lines, that is, the relay line 14 for the wireless LAN and the transmission line 28 for the wired LAN must be used in the configuration for connecting the wireless LAN and the wired LAN using However, there is a problem in that a large number of unnecessary frames are generated as a result of the frame relaying being complicated even though the variable RTL is used.

For example, a wireless L existing in the cell 100a
When a wireless frame is transmitted from the AN terminal 10a, this wireless frame is received by both the relay devices 12a and 12c. When the wireless frame is received by the relay devices 12 a and 12 c, the relay line frame with RTTL = 1 is transmitted to the relay line 14. Relay device 12a
The relay line frame from the relay device 12b is received by both the relay devices 12b and 12c, and the relay line frame from the relay device 12c is received by both the relay devices 12a and 12b. The relay device 12b which has received the relay line frame from the relay device 12a via the relay line 14 has RTTL = 2.
Wireless frame is transmitted to the cell 100b, and the wireless frame is received by the relay line 12c, the wireless wired bridge 26, and the wireless LAN terminal 10b.
A street relay route occurs. In addition, the relay device 12 which receives the relay line frame from the relay device 12a via the relay line 14
c transmits the same wireless frame in the extended cell in which the cells 100a and 100b are integrated, and this wireless frame is received by the relay devices 12a and 12b, the wireless wired bridge 26, and the wireless LAN terminals 10a and 10b.
Five kinds of relay routes occur. Similarly, the relay device 12c
When a relay line frame with RTL = 1 is transmitted from RTL to RTL, a wireless frame with RTTL = 2 is transmitted by the relay devices 12a and 12b into the cell 100a or 100b, respectively (2 + 3 relay routes). Therefore, cell 1
The number of relay paths generated when a wireless frame is transmitted from the wireless LAN terminal 10 in 00a is 13. Since there are three routes to the wireless wired bridge 26, a total of 10 unnecessary frames are generated.

[0021] The present invention has been made to solve the above problems, and the structure of a frame transmitted by wire between relay devices is changed to an existing wire LAN such as IEEE802.3 or Ethernet. By using the same configuration as the frame used for the wireless LAN, a wired LAN terminal and a wireless LAN terminal are mixed and the facility cost is reduced without using a wireless wired bridge and therefore without using a plurality of wired transmission lines. The purpose is to realize a cheap LAN. Further, according to the present invention, a variable cell inserted in a radio frame to manage a relay history is manipulated only at the time of wireless transmission from the relay device (filtering), thereby providing a complicated cell arrangement and a complicated relay device arrangement. It is an object of the present invention to prevent the occurrence of complicated relay paths and the occurrence of a large number of unnecessary frames even in a LAN having the above. A further object of the present invention is to eliminate the need for providing a relay device or a wireless LAN terminal with complicated functions such as power measurement in order to achieve the above object. The present invention further enables each relay device to individually manage a wireless LAN terminal existing within the wireless communication range of the relay device and a wireless and wired LAN terminal capable of communicating via another relay device. An object of the present invention is to prevent the occurrence of a communication disabled state and the intricacy of a frame relay route due to the movement of a wireless LAN terminal between cells. In addition to the above, the present invention provides an OSI (Open System Interconne
layer (physical layer) and the second layer (data link layer) of M.
By using only the layers below the AC layer, medium speed LAN while maintaining the communication connection in the upper layer
The purpose is to enable the movement of terminals between cells in such cases as.

[0022]

In order to achieve such an object, a LAN according to the present invention includes a wireless LAN terminal for wirelessly transmitting and receiving a wireless frame, a wired LAN terminal for transmitting and receiving a wired frame by wire, and Frame transmission between a wireless LAN terminal within a wireless communication range and a wireless LAN terminal within a wireless communication range of another relay device, and between a wireless LAN terminal and a wired LAN terminal within its own wireless communication range A plurality of relay devices for relaying the wireless LAN, wherein the wireless frame includes a loop prevention bit indicating whether the transmission source is the wireless LAN terminal or the relay device.
The terminal sets a first value in the loop prevention bit of the wireless frame to be transmitted, and when each relay device receives the wireless frame in which the loop prevention bit has the first value, converts the frame into a wired frame. Then, when a wired frame addressed to the wireless LAN terminal is received, the wired frame is converted into a wireless frame in which the loop prevention bit is set to a second value different from the first value, and the frame is transmitted. It is characterized in that the wireless or wired frame is discarded when the wireless frame having the second value of the prevention bit is received and when the wired frame addressed to the wired LAN terminal is received.

In the LAN according to the present invention, each relay device is a wireless LAN terminal that is within the wireless communication range of the relay device and is not within the wireless communication range of any other relay device. A wireless table for registration, a wireless LAN terminal within the wireless communication range of any other relay device, a means for storing a wired table for registering the wired LAN terminal, and a means for storing the wired table not registered in the wireless table When a wireless frame is received from a wireless LAN terminal, after confirming that the wireless frame is not received by another relay device, the wireless LAN terminal is registered in the wireless table and a means for registering it in the wireless table. A means for deleting the registration of the wireless LAN terminal from the wired table when the wireless LAN terminal is also registered in the wired table at the same time. When receiving the wired frame through the other relay device from when received and the wireless LAN terminal wired frame from the wired LAN terminal, means for registering the wired LAN terminal or a wireless LAN terminal to a wired table,
Means for deleting the registration of the wireless LAN terminal from the wireless table when the wireless LAN terminal registered in the wired table is also registered in the wireless table at the same time.

In the LAN according to the present invention, each relay device further sends the wireless LAN terminal for a time period set by a random number that the wireless frame received from the wireless LAN terminal is not received by another relay device. It is characterized by confirming that the original wired frame is not transmitted.

In addition, in the LAN according to the present invention, each relay device is a wireless LAN terminal and a wired LAN terminal in which registration, deletion of registration, and confirmation of presence / absence of registration have not been performed for a predetermined time or more with respect to a wired table or a wireless table. Is registered and deleted.

The relay apparatus according to the present invention is used in a LAN having a wireless LAN terminal for wirelessly transmitting and receiving wireless frames and a wired LAN terminal for wiredly transmitting and receiving wired frames, and is within its own wireless communicable range. Between a wireless LAN terminal within the wireless communication range of the other relay device and within the wireless communication range of its own
A relay device that relays frame transmission between a terminal and a wired LAN terminal, and when transmitting from the wireless LAN terminal, receives a wireless frame including a loop prevention bit in which a first value is set. A means for converting a wired frame to a wired frame and transmitting the wired frame to a wireless frame in which when the wired frame addressed to the wireless LAN terminal is received, the wired frame is converted into a wireless frame in which the loop prevention bit has a second value different from the first value. And a means for discarding the wireless or wired frame when a wireless frame whose loop prevention bit has a second value is received and when a wired frame addressed to the wired LAN terminal is received. Is characterized by.

The relay device according to the present invention further has a wireless table for registering a wireless LAN terminal which is within its own wireless communication range and is not within the wireless communication range of any other relay device. And a means for storing a wired LAN table for registering the wireless LAN terminal and the wired LAN terminal within the wireless communication range of any of the other relay devices, and a wireless LA not registered in the wireless table.
When a wireless frame is received from an N terminal, it is confirmed that the wireless frame is not wirelessly received by another relay device, and then the wireless LAN terminal is registered in the wireless table and a means for registering the wireless LAN terminal in the wireless table. When the wireless LAN terminal is also registered in the wired table at the same time, a means for deleting the registration of the wireless LAN terminal from the wired table, a method for receiving a wired frame from the wired LAN terminal, and another relay device from the wireless LAN terminal are provided. When a wired frame is received via the wired LAN terminal or wireless LAN
And a means for registering the terminal in the wired table and a means for deleting the registration of the wireless LAN terminal from the wireless table when the wireless LAN terminal registered in the wired table is also registered in the wireless table at the same time. And

The relay device according to the present invention indicates that the wireless frame received from the wireless LAN terminal is not received by the other relay device for a period of time set by a random number and the wireless L
It is characterized by confirming that a wired frame whose source is the AN terminal is not transmitted.

The relay device according to the present invention, with respect to the wired table or the wireless table, deletes the registration of the wireless LAN terminal and the wired LAN terminal which have not been registered, deleted or registered for a predetermined time or longer. It is characterized by comprising means.

[0030]

In the present invention, the loop prevention bit indicating the sender is provided in the wireless frame transmitted and received between the wireless LAN terminal and the relay device. A first value is set to this loop prevention bit for transmission from the wireless LAN terminal, and a second value is set to transmission from the relay device. In each relay device, the operation using this loop prevention bit is executed when relaying the received wireless frame or wired frame.

For example, assume that a wireless frame is transmitted from a wireless LAN terminal. The loop prevention bit of this radio frame is set to the first value as described above. When this wireless frame is received by the relay device, since the loop prevention bit in the received frame has the first value, conversion into a wired frame and transmission of the wired frame are executed. When the wired frame thus transmitted is received by another relay device, the relay device which has received the wired frame transmits a wireless frame having the loop prevention bit set to the second value. Even if this frame is received by another relay device within the wireless communication range of the transmitting relay device, the second value is set in the loop prevention bit of the wireless frame, so that the relay of the receiving side is performed. As a result, the wireless frame is discarded in the device.

Therefore, in the present invention, when the wireless frame is received by the relay device, the wired frame corresponding to the wireless frame is not transmitted by wire, so that the trouble such as infinite loop transmission between the relay devices does not occur. . Further, unlike the prior proposal shown in FIGS. 11 to 16, when a wired frame is transmitted from one relay device to another relay device, it is necessary to store information indicating a relay history in the wired frame. Therefore, it is possible to use the frame structure of an existing wired LAN as a wired frame as it is. Therefore, a single wired transmission line is used without any modification to the structure or function of each wired LAN terminal. Then, it becomes possible to construct a wired / wireless mixed LAN. As a result, it is possible to prevent a problem that a large number of unnecessary frames are generated as a result of the complicated frame relay path. In addition, since it is possible to identify whether the wireless frame received by each relay device is from another relay device or from a wireless LAN terminal only by the loop prevention bit described above, it is possible to measure the power at the relay device or the wireless LAN terminal. Etc. are not necessary, and the above-described operation occurs with a simple device configuration.

In the present invention, the movement of the wireless LAN terminal between the wireless communicable ranges (for example, cells) of each relay device is further grasped for each relay device by the process using the wireless table and the wired table.

First, when a wireless frame is received from a wireless LAN terminal that has not been registered in the wireless table until then, the relay device determines that the wireless frame is transmitted to another device by means such as monitoring the wired transmission status between the relay devices. Check that it is not received by the relay device. When such confirmation is obtained, the relay device registers the wireless LAN terminal in the wireless table and, if it is also registered in the wired table, deletes the wireless LAN terminal from the wired table. .

After that, it is assumed that the wireless LAN terminal has moved into the wireless communication range of another relay apparatus (including the overlapping area of the wireless communication range of both relay apparatuses). Then, the wireless frame transmitted from this wireless LAN terminal is ready to be received by both relay devices. In that case, when the relay device that has already registered this wireless LAN terminal in the wireless table detects that the wireless frame transmitted from the same wireless LAN terminal is transmitted as a wired frame by another relay device, the wireless device transmits this wireless LAN terminal. The LAN terminal is registered in its own wired table and is deleted from its own wireless table.

By such management, the wireless LAN of each relay device is within the wireless communication range of the relay device and is not within the wireless communication range of any other relay device. The terminal is registered, and the wired table of the relay device has a wireless LAN terminal and a wired LA terminal within the wireless communication range of any other relay device.
Since the N terminals are registered, it is possible to appropriately deal with the movement of the wireless LAN terminal.

Furthermore, when a wireless frame from a wireless LAN terminal not registered in the wireless table is received,
In order to know whether the wireless frame has not been received by another relay device, it suffices to detect whether or not the frame has been converted to a wire frame by another relay device by monitoring the status of wire transmission. . In that case, it is preferable to set a random number for the monitoring time of wired transmission in each relay device. In this way, when a wireless frame from the same wireless LAN terminal is received by a plurality of relay devices, this wireless LAN terminal is registered on the wireless table of the relay device for which the shortest monitoring time is set. As a result, the same wireless LAN terminal (that is, the wireless LAN terminal located in the overlapping portion of the wireless communicable range of the plurality of relay devices) is not redundantly registered in the wireless tables of the plurality of relay devices.

In the present invention, furthermore, the wireless LAN terminal which has not been registered, deleted and registered or not checked for a predetermined time is deleted from the wired table or the wireless table. For example, a wireless LAN terminal is
In the case where the wireless LAN terminal is out of the wireless communication range of any of the AN devices, or when the wireless LAN terminal loses its function due to a failure or the like and cannot perform wireless transmission, By this monitoring, registration deletion of this wireless LAN terminal is executed. Therefore, in the present invention, the management of the wireless LAN terminal using the wired table and the wireless table can be regarded as actually participating in the LAN.
Since it is executed only for the AN terminal, the storage space for realizing the wired table and the wireless table can be suppressed to the necessary minimum scale.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same or corresponding configurations as those of the conventional example or the previously proposed example shown in FIGS. 7 to 16 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a LAN according to an embodiment of the present invention.
The configuration of is shown. In this figure, three relay devices 12 a to 12 c are connected by a relay line 14. A wired LAN terminal 30 is directly connected to the relay line 14. Furthermore, the wireless LAN terminals 10a and 10b
The communicable ranges 300a and 300b of the relay device 12b overlap each other in this figure, and the relay device 12b is provided in the overlapping portion.
Is located. The relay device 12a is the wireless LAN terminal 10
a is within the communicable range 300a but not within the wireless LAN terminal 10b, and the relay device 12b is a wireless LAN.
Although it is within the communicable range 300b of the terminal 10b, the wireless L
It is not within the communicable range 300a of the AN terminal 10a.

The first feature of this embodiment is that
Between the relay devices 12a to 12c or with the wired LA
Unlike the previously proposed example, the wired frame transmitted to and from the N terminal 30 does not include variables such as RTTL,
Wired LA compliant with IEEE802.3 and Ethernet
It has the same configuration as the N frame. Therefore, in this embodiment, the wired LAN terminal 30 can be directly connected to the trunk line 14 as described above. In addition to eliminating the need for the wireless wired bridge 26 as in the previously proposed example,
The problem of using a plurality of wired transmission lines does not occur in this embodiment.

The second characteristic of this embodiment is that a loop prevention bit indicating the type of the transmission source is provided in the radio frame. Although this loop prevention bit corresponds to the variable RTTL in the previously proposed example, it is deleted from the frame when it is transmitted on the trunk line 14. That is, when the wired frame received via the relay line 14 is converted into a wireless frame and transmitted, the relay devices 12a to 12c add / set the loop prevention bit, and also the wireless LAN.
When the wireless frame received from the terminal 10a or 10b is converted into a wired frame, the relay devices 12a to 12c delete the loop prevention bit. As a result of such an operation, the frame structure transmitted on the trunk line 14 can be made the same as the frame structure in the existing wired LAN. In addition, the wireless cable bridge 26
In addition to abolishing the
It is possible to prevent problems such as the generation of many unnecessary frames. Further, RTL is 2 bits because it is necessary to count 0 to 2, but 1 bit is enough for the loop prevention bit.

The third characteristic of the present embodiment is that the above-mentioned processing is realized by the operations in the physical layer and the MAC layer, and there is no influence on the upper layer of the OSI reference model. is there. As a result, for example, when viewed from the application, usability that is no different from existing wired LANs and wireless LANs can be realized.

The fourth characteristic of this embodiment is that the movement of the wireless LAN terminal is dealt with by managing the wired table and the wireless table in each of the relay devices 12a to 12c. Further, regarding the registration and the registration deletion of the wireless table and the wired table, monitoring of wired transmission on the relay line 14 is executed in order to prevent duplicate registration and unnecessary registration.

FIG. 2 shows the functional configuration of the relay devices 12a to 12c used in this embodiment. In this embodiment, a timer 32 and an interrupt controller 34 are added to the configuration shown in FIG. The timer 32 is, for example, registered in a wireless table, which will be described later, or maintains the wired table or the wireless table (that is, the wireless LAN terminal 10a or 1 which has not been accessed for a predetermined time or more).
0b) (register deletion of 0b). The interrupt controller 34 activates the latter, that is, the maintenance operation of the wireless table and the wired table, and therefore generates an interrupt at a predetermined frequency. Further, in the ROM 22, FIG.
~ The procedure shown in Fig. 5 is stored as a program.
The CPU 20 executes the program on the ROM 22.

Next, in this embodiment, each relay device 12
The procedures performed by a to 12c will be described according to FIGS.

(1) Transmission from Wired LAN Terminal 30 First, the wired LAN terminal 30 connected to the trunk line 14
When, for example, a wired frame is transmitted from the wireless LAN terminal 10a to the wireless LAN terminal 10a, the MAC address of the wired LAN terminal 30 is used as the source address and the M address of the wireless LAN terminal 10a is used as the destination address in the header of the wired frame.
The AC address is set respectively. When this wired frame is received by, for example, the relay device 12a via the wired LAN interface 18 (see FIGS. 3 and 40).
0), the CPU 20 of the relay device 12a registers the source address in the received wired frame in the wired table on the RAM 24 (402). Destination wireless LAN terminal 1
0a until that time (that is, from the start of the relay device 12a until now or from the deletion by maintenance until now)
If it has not been registered in the wired table of a, the CPU 20 of the relay device 12a wirelessly transmits the wireless frame in which the loop prevention bit is set to "1" (404) by the wireless device 16 (406).

The wireless frame transmitted from the relay device 12a is received by the wireless LAN terminal existing within the wireless communicable range of the relay device 12a. Here, the wireless frame transmitted from the relay device 12a includes the same source address and destination address as those contained in the wired frame received from the wired LAN terminal 30 by the relay device 12a. . Therefore, even if a plurality of wireless LAN terminals exist within the communicable range of the relay device 12a, wireless LAN terminals other than the destination wireless LAN terminal 10a can ignore this wireless frame.

On the other hand, the radio frame transmitted from the relay device 12a is also received by another relay device within the communicable range of the relay device 12a, for example, the relay device 12b. The CPU 20 of the relay device 12b receives the wireless frame by the corresponding wireless device 16 (see FIG. 4,
408), the value of the loop prevention bit included in the radio frame is checked (410). If there is an error in the received wireless frame (412), the CPU
20 discards the received wireless frame (414) and ends the process. When the wireless frame from the relay device 12a is received by the relay device 12b as described above,
Prior to step 404 executed by the relay device 12a, the loop prevention bit is set to "1", that is, a value indicating the transmission from the relay device. Therefore, in this case (416), the relay device 12b
CPU 20 discards the received wireless frame (41
4), the process ends.

Thus, in this embodiment, the wired L
A wired frame transmitted from the AN terminal 30 is converted into a wireless frame by any of the relay devices 12a to 12c.
When transmitted, even if this wireless frame is received by another relay device, the wireless frame is discarded by the other relay device. In other words, wire L
The transmission of the wired frame from the AN terminal 30 does not trigger an infinite transmission loop between relay devices or a large number of unnecessary frames.

(2) Transmission from wireless LAN terminal to wired LAN terminal For example, when data is to be transmitted from the wireless LAN terminal 10a to the wired LAN terminal 30, the wireless LAN terminal
The terminal 10a transmits its own MAC address as the source address, the MAC address of the wired LAN terminal 30 as the destination address, and a wireless frame with the loop prevention bit set to "0". The wireless frame transmitted from the wireless LAN terminal 10a is received by another wireless LAN terminal (not shown) and the relay devices 12a and 12b within the communicable range 300a of the wireless LAN terminal 10a. Other wireless LAN terminals that have received the wired frame from the wireless LAN terminal 10a can ignore the wireless frame by detecting that the destination address included in the wireless frame is not their own MAC address. it can.

On the other hand, a relay device within the communicable range 300a of the wireless LAN terminal 10a, for example, the relay device 12a.
Receives the wireless frame from the wireless LAN terminal 10a by the wireless device 16 (408). The CPU 20 of the relay device 12a checks the loop prevention bit in the radio frame received after executing the above step 412 (4
10). In this case, the loop prevention bit is set to the wireless LAN.
Since the value "0" indicating the transmission from the terminal is set (416), the CPU 20 determines the source address in the received wireless frame as the content of the wireless table stored in the corresponding RAM 24. Compare (418).
If the MAC address of the wireless LAN terminal 10a is already registered on the wireless table of the relay device 12a at that time (420), the CPU 20 of the relay device 12a deletes the loop prevention bit from the received wireless frame, etc. After executing the processing, the frame is transmitted to the trunk line 14 (422). The frame transmitted to the relay line 14, that is, the wired frame is received by the wired LAN terminal 30 which is the destination.

The wired frame is also received by another relay device connected to the relay line 14, for example, the relay device 12b (400). CP of relay device 12b
The U20 registers the source address in the received wired frame, that is, the MAC address of the wireless LAN terminal 10a, in the corresponding wired table on the RAM 24 (402).
At this point, the wireless LA is displayed on the wireless table of the relay device 12b.
If the MAC address of the N terminal 10a is not registered (424, 426), the CPU 20 compares the destination address in the received wired frame with the contents on the wired table (428). For example, if communication related to the wired LAN terminal 30 has been performed within a predetermined time before execution of step 428, the MAC address of the wired LAN terminal 30 is registered on the wired table of the wireless LAN terminal 12b. In that case (430), the relay device 12b discards the received wired frame (432).

Therefore, the relay line 1 is connected by the relay device 12a.
4, even if the wired frame addressed to the wired LAN terminal 30 is received by the relay device 12b, as long as the communication related to the wired LAN terminal 30 is performed at an appropriate frequency during a predetermined period before that. The situation in which the relay device 12b transmits a wireless frame corresponding to the wired frame does not occur. If communication related to the wired LAN terminal 30 has not been performed since the maintenance of the wired table was performed last time (described later), step 4
Although it is determined in 30 that "the same MAC address as the destination address is not registered in the wired table", even in that case, the loop prevention bit in the wireless frame transmitted in step 406 is set to step 4
Since it is set to "1" in 04, this radio frame will not be sent again onto the trunk line 14 by another relay device.

Further, the wire L is sent from the wireless LAN terminal 10a.
When the wireless frame addressed to the AN terminal 30 is converted into a wired frame by the relay device 12a and this wired frame is received by the relay device 12b, the MAC address of the wireless LAN terminal 10a is already displayed on the wireless table of the relay device 12b. Is registered (426), this relay device 1
The CPU 20 of 2b uses the same MAC as the source address.
The address is deleted from the wireless table (434). That is, when the wired frame corresponding to the wireless frame transmitted by the wireless LAN terminal can be received via the relay line 14, the wireless LAN terminal receives the wireless device.
Since it can be regarded as belonging to the communication range of the relay device other than b (here, the relay device 12a), registration in the wired table is executed in step 402 and the wireless table is registered in step 434. Delete the registration from. By this, the same wireless LAN terminal,
That is, it is possible to prevent a situation in which 10a is registered in both the wired table and the wireless table of the single relay device 12b.

Further, the wireless LAN terminal 10a sends a wire L
When a wireless frame addressed to the AN terminal 30 is received by the relay device 12a (408), this relay device 12a
MAC of the wireless LAN terminal 10a still on the wireless table of
When the address is not registered (420), in the present embodiment, the relay device 12a monitors the frame transmission status on the relay line 14 (436). More specifically, the CPU 20 of the relay device 12a has a predetermined range, for example, 1
Generate a random time within the range of ms to 20 ms,
The random number time is counted by the timer 32. During this random number time, the CPU 20 determines that the source address is the wireless LAN.
It is monitored via the wired LAN interface 18 whether or not a wired frame having the MAC address of the terminal 10 a and the destination address of the wired LAN terminal 30 is transmitted on the relay line 14. As a result of this monitoring, when it is determined that such a frame is not transmitted on the relay line 14 (438), the wireless frame transmitted by the wireless LAN terminal 10a is received by any other relay device. It is possible to assume that the relay device 12a has not received the same wireless frame (or has a long random number time set in another relay device that has received the same wireless frame). Therefore, the CPU 20 of the relay device 12a determines the source address in the received wireless frame. While registering in the wireless table on the corresponding RAM 24 (440), and if this source address also exists in the wired table (442, 444), the same MAC as the source address is used from the wired table. The address is registered and deleted (446). After that, the CPU 20 executes the above-described step 422. On the contrary, when the transmission of the wired frame which is the monitoring purpose is detected during the random time monitoring (4
38), the communicable range 300a of the wireless LAN terminal 10a
Since it is clear that there is another relay device inside, the CPU 20 of the relay device 12a discards the received wireless frame (414).

Therefore, from the wireless LAN terminal 10a to the wired L
Even when the communication is addressed to the AN terminal 30, the problems that have occurred in the conventional example and the previous proposal do not occur.

(3) From a wireless LAN terminal to another wireless LAN
Communication to a terminal For example, the wireless LAN terminal 10a is connected to another wireless LAN terminal 10
It is assumed that a wireless frame is transmitted to b. In this case, the destination wireless LAN terminal 10b is the wireless LAN terminal 1
If it is located within the communicable range 300a of 0a, direct wireless communication is executed between both wireless LAN terminals. In this case, the relay device existing in the communicable range 300a of the wireless LAN terminal 10a, for example, 12a can also receive the wireless frame transmitted from the wireless LAN terminal 10a. However, as a result of this reception, the wired frame is relay line 1
4 is transmitted to the relay device 14, the relay device that receives the wired frame via the relay line 14 executes step 404, that is, the process of setting the loop prevention bit to “1”, so that there is no limit between the relay devices. Loop transmission does not occur.

When the destination wireless LAN terminal 10b is not within the communicable range 300a of the wireless LAN terminal 10a as shown in FIG. 1, the relay which receives the wireless frame from the wireless LAN terminal 10a is relayed. The operation shown in FIG. 4 is executed by the device, for example, 12 a, and the wired frame is sent out on the trunk line 14. This wired frame is received by the relay devices 12b and 12c within the communicable range 300b of the wireless LAN terminal 10b in FIG. These relay devices 12b and 12c execute the operation shown in FIG. That is, the wireless LAN terminal 1
The MAC address of 0a corresponds to these relay devices 12b and 1
2c is registered in the wired table and deleted from the wireless table if necessary (402, 434), and the MAC address of the wireless LAN terminal 10b, which is the destination address, is compared with the contents of the wired table (42).
8). After the MAC address of the wireless LAN terminal 10b has been deleted from the wired table due to maintenance or the like, if communication relating to the wireless LAN terminal 10b has not been performed by this point of time, the CP of these relay devices 12b and 12c
The U20 sets the loop prevention bit to "1" and then transmits the radio frame (404, 406). From the wired table to the wireless LAN terminal 10 due to the previous maintenance, etc.
Even if the communication related to the wireless LAN terminal 10b has been performed up to this point after the registration and deletion of the MAC address of b, the wireless LAN terminal on the wireless table of the relay devices 12b and 12c. The relay device in which the MAC address of 10b is registered (that is, the relay device in which the MAC address of the wireless LAN terminal 10b is not registered in the wired table) is processed in steps 404 and 406.
To execute. The other relay device executes step 432 and discards the received wired frame.

Therefore, in this embodiment, the wireless LA
Even when transmitting from the N terminal to the wireless LAN terminal, the above-mentioned problems do not occur.

(4) Movement of Wireless LAN Terminal In this embodiment, the wired and wireless LAN terminals are managed using the wireless table and the wired table as described above. That is, each of the relay devices 12a to 12c
Is within the communicable range of itself and is not within the communicable range of the other relay device, and is in the overlapping portion of the communicable range of the wireless LAN terminal and the communicable range of the other one, and
The MAC address of the wireless LAN terminal that has acquired the registration right by the processing of 36 and 438 is registered in the wireless table, and the MAC address of the other wireless LAN terminals and the MAC address of the wired LAN terminal 30 are registered. Registered on the wired table. Such management is significant in that it can respond immediately when the wireless LAN terminal moves.

For example, as shown in FIG.
It is assumed that the N terminal 10a moves to the right side in the figure and the communicable range 100a of the relay device 12a and the communicable range 300a of the wireless LAN terminal 10a no longer overlap. Also,
It is assumed that only the relay device 12c is located within the communicable range 300a of the wireless LAN terminal 10a.

State before such movement (FIG. 1)
Then, each of the relay devices 12a to 12c is connected to the wireless LAN terminal 10
Excluding the transitional period during which the existence and position of a and 10b and the existence of the wired LAN terminal 30 are excluded, for example, the wired table of the relay device 12a contains the MAC addresses of the wired LAN terminal 30 and the wireless LAN terminal 10b. , The MAC address of the wireless LAN terminal 10a is registered in the wireless table, and the wired table is stored in the wired table of the relay device 12b.
MA of the AN terminal 30 and the wireless LAN terminals 10a and 10b
The C address is registered, and M of the wired LAN terminal 30 and the wireless LAN terminal 10a is registered in the wired table of the relay device 12c.
The AC address is the wireless LAN terminal 10 in the wireless table.
The MAC addresses of b are registered respectively. If this situation changes to the situation shown in FIG. 6, the wireless LA
The N terminal 10a is the communicable range 100a of the relay device 12a.
As a result, the MAC address of the wireless LAN terminal 10a is deleted from the wireless table of the relay device 12a and registered in the wired table. This is the wireless LAN terminal 10
The wireless frame transmitted from a is transmitted to the wired frame by the relay device 12c, and the CPU 2 of the relay device 12a indicates that the wired frame is transmitted to the relay line 14.
0 is the result detected through the operations of steps 402, 424, 426 and 434.

With this movement, the relay device 12
MAC of the wireless LAN terminal 10a from the wired table to c
The address is deleted and newly registered in the wireless table.
This is because when the relay device 12c receives a radio frame transmitted from the wireless LAN terminal 10a (408), the CPU 20 of the relay device 12c causes the CPU 20 of the relay device 12c to perform steps 436 and 4.
Monitoring and frame detection at random time according to No. 38,
Based on the result, the contents of the wireless table or the wired table are operated (440 to 445). Therefore, according to the present embodiment, it is possible to preferably deal with the movement of the wireless LAN terminals 10a and 10b.

(5) Maintenance of Wired Table and Wireless Table The CPU 20 of each of the relay devices 12a to 12c executes the interrupt processing shown in FIG. 5 in response to the interrupt from the interrupt controller 34. This interrupt process is a process for maintaining the wired table and the wireless table.

That is, the CPU 20 has a corresponding RAM.
It is checked at what point in the past each MAC address registered in the wired table or the wireless table on 24 was accessed (500). That is, the time when registration is performed for each MAC address on the wired table or the wireless table, and the time when transmission / reception is performed for the terminal having the MAC address is inspected. In order to enable this inspection, the time is output on the wired table and the wireless table when registering the MAC address and comparing it with the source address and the destination address.

As a result of this inspection, when a MAC address which has not been accessed for a predetermined time is found (502,
504), the CPU 20 deletes the registration of this MAC address from the corresponding wired or wireless table (50).
6). This process applies to all Ms on the wired or wireless table.
Performed on AC address.

Therefore, according to the present embodiment, the MAC address which has not been accessed for the predetermined time or longer is deleted from the wired table or the wireless table. Therefore, for example, a terminal that has become incapable of communication on the road or a LAN that has moved
With respect to the wireless LAN terminal that cannot function as a part of the above, it can be out of the management range of the wired table or the wireless table. This leads to effective use of the check capacity of the RAM 24.

[0069]

As described above, according to the present invention,
Each relay device determines whether the wireless frame is transmitted from the relay device or the wireless LAN terminal using the loop prevention bit provided in the wireless frame, and based on the result, the transmission of the wired frame or Since the discarding of frames is selectively executed, it is not necessary to include the relay history information in the wired frame, and the frame configuration used in the existing wired LAN as the wired frame can be used as it is. . As a result, without using a means such as a wireless wired bridge,
Therefore, without using a plurality of wired transmission lines, the wired L
A LAN in which AN terminals and wireless LAN terminals are mixed can be constructed. Furthermore, by using this loop prevention bit, it is possible to prevent a problem such as a large number of unnecessary frames. Further, since the loop prevention bit is used, it is not necessary to provide a complicated function such as power measurement of a signal received by each relay device or each wireless LAN terminal, and the simplicity of the device configuration can be maintained.

Further, according to the present invention, the wireless table and the wired table are managed by using the wireless table and the wired table for each relay device, and the transmission / reception status of the wireless frame and the transmission status of the wired frame are related. Since the contents of the wireless table and the wired table are updated accordingly, the wireless LAN terminal continues to move even when the wireless LAN terminal moves from the wireless communicable range of one relay device to the communicable range of another relay device. Management can be performed. Further, when setting the arrangement of the relay devices, it is not necessary to consider the positional relationship of the wireless communication range of each relay device in detail, which facilitates the design and elaboration of the LAN. Further, the wireless table and the wired table have MACs of the respective wireless LAN terminals and wired LAN terminals.
Since it is sufficient to register the address and the like, the above management can be achieved only by the processing in the first layer and the second layer of the OSI reference model.

Furthermore, according to the present invention, when a wireless frame is received from a wireless LAN terminal, it is determined whether or not this wireless LAN terminal should be registered in the wireless table.
Since it is confirmed that the wired frame from the terminal is not transferred, and it is registered when the confirmation is obtained, the wireless LAN terminal which should not be registered in the wireless table should be registered in the wireless table by mistake. Is prevented. Further, since the monitoring time at that time is set to a random number in each relay device, this wireless LAN terminal is registered on the wireless table of the relay device for which the shortest time is set, resulting in a single wireless LAN. It is possible to prevent a terminal from being simultaneously registered on the wireless tables of a plurality of relay devices by a simple method.

According to the present invention, the wireless LAN terminal and the wired LAN terminal which have not been accessed for registration or the like for a predetermined time or more are registered and deleted from the wired table or the wireless table. Wireless LAN terminal and wired LAN that can no longer participate in communication due to
The economical situation of registering the terminal as it is in the wired table or the wireless table is eliminated, and the storage space used for storing the wired table or the wireless table in each relay device can be saved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a LAN according to an embodiment of the present invention.

FIG. 2 is a functional block diagram showing a configuration of a relay device in this embodiment.

FIG. 3 is a flowchart showing a flow of an operation of wirelessly transmitting a received wired frame among the operations executed by each relay device in this embodiment.

FIG. 4 is a flowchart showing a flow of an operation of transmitting a received wireless frame by wire among the operations executed by each relay device in this embodiment.

FIG. 5 is a flowchart showing a flow of operations executed by each relay device in this embodiment in response to an interrupt in order to maintain a wired table and a wireless table.

FIG. 6 is a conceptual diagram for explaining the operation of the present embodiment when the wireless LAN terminal moves.

FIG. 7 is a conceptual diagram showing a configuration of a LAN according to a conventional example.

FIG. 8 is a functional block diagram showing a configuration of a relay device in this conventional example.

FIG. 9 is a diagram showing a frame structure used in a wireless LAN.

FIG. 10 is a conceptual diagram showing a case where a plurality of relay devices are arranged in an overlapping range of a plurality of cells in this conventional example.

FIG. 11 is a diagram showing a radio frame configuration previously proposed by the applicant of the present application.

FIG. 12 is a diagram showing a trunk line fume structure proposed by the applicant of the present application.

FIG. 13 is a flowchart showing a flow of an operation of converting a received wireless frame into a relay line frame and transmitting the received wireless frame to the relay line, among the operations performed by the relay device according to the applicant's previous proposal.

FIG. 14 is a flowchart showing a flow of an operation of converting a received trunk line frame into a wireless frame and wirelessly transmitting, among the operations executed by the relay device in the applicant's previous proposal.

FIG. 15 is a conceptual diagram showing the effect of RTTL in the previous proposal.

FIG. 16 is a conceptual diagram showing a problem of the previously proposed example.

[Explanation of symbols]

10a, 10b wireless LAN terminals, 12a to 12c relay devices, 14 relay lines, 30 wired LAN terminals.

Claims (8)

[Claims] 1. A wireless LA for wirelessly transmitting and receiving wireless frames
N terminal, a wired LAN terminal that sends and receives a wired frame by wire, a wireless LAN terminal that is within its own wireless communication range, and a wireless LAN that is within the wireless communication range of another relay device.
Wireless LA between terminals and within its own wireless communication range
In a LAN having a plurality of relay devices for relaying frame transmission between the N terminal and the wired LAN terminal, the wireless frame includes a loop prevention bit indicating whether the transmission source is a wireless LAN terminal or a relay device, The wireless LAN terminal sets a first value in the loop prevention bit of the wireless frame to be transmitted, and when each relay device receives the wireless frame in which the loop prevention bit has the first value, the frame is set to the wired frame. When the wired frame addressed to the wireless LAN terminal is received, the wired frame is converted into a wireless frame in which a second value different from the first value is set in the loop prevention bit, and then transmitted. When a wireless frame whose loop prevention bit has a second value is received or when a wired frame addressed to a wired LAN terminal is received, the wireless or wireless LAN, characterized in that to discard the frame. 2. The LAN according to claim 1, wherein each relay device is within a wireless communication range of the relay device and is not within a wireless communication range of any other relay device. Wireless table for registering the wireless L and wireless L within the wireless communication range of any other relay device
A means for storing a wired table for registering the AN terminal and the wired LAN terminal, and when a wireless frame is received from a wireless LAN terminal not registered in the wireless table, the wireless frame is received by another relay device. After confirming that it is not
A means for registering the wireless LAN terminal in the wireless table, a means for deleting the registration of the wireless LAN terminal from the wired table when the wireless LAN terminal registered in the wireless table is simultaneously registered in the wired table, and the wired LAN When a wired frame is received from a terminal or when a wired frame is received from a wireless LAN terminal via another relay device, a means for registering the wired LAN terminal or the wireless LAN terminal in the wired table, and a wireless registered in the wired table A LAN having means for deleting the registration of the wireless LAN terminal from the wireless table when the LAN terminal is also registered in the wireless table at the same time. 3. The LAN according to claim 2, wherein each relay device determines that a wireless frame received from a wireless LAN terminal is not received by another relay device, and the wireless LAN terminal is set for a time period set by a random number. A LAN characterized by confirming that a wired frame as a transmission source is not transmitted. 4. The LAN according to claim 2, wherein each relay device relates to a wired table or a wireless table,
A LAN characterized by deregistering a wireless LAN terminal and a wired LAN terminal that have not been registered, deregistered, or not checked for registration for a predetermined time or longer. 5. A wireless LA for wirelessly transmitting and receiving wireless frames
Between a wireless LAN terminal that is used in a LAN that has N terminals and a wired LAN terminal that sends and receives wired frames by wire, and that is within the wireless communication range of its own wireless device and the wireless LAN terminal that is within the wireless communication range of another relay device. And a relay device for relaying frame transmission between a wireless LAN terminal and a wired LAN terminal within its own wireless communicable range, the wireless including a loop prevention bit having a first value set for transmission from the wireless LAN terminal. A means for converting the wireless frame into a wired frame when the frame is received and transmitting the converted frame; and a second frame having a loop prevention bit for the wired frame different from the first value when receiving the wired frame addressed to the wireless LAN terminal. A means for converting into a wireless frame with a set value and transmitting it, and receiving a wireless frame whose loop prevention bit has a second value Relay apparatus characterized by and a means for discarding the wireless or wired frame when the case and receiving the wired LAN terminal destined wired frame. 6. The wireless LAN according to claim 5, wherein the wireless LAN is within its own wireless communication range and is not within the wireless communication range of any other relay device.
A wireless table for registering a terminal, a wireless LAN terminal within a wireless communicable range of any other relay device, a means for storing a wired table for registering the wired LAN terminal, and a means for registering in the wireless table. When a wireless frame is received from a wireless LAN terminal that is not registered, the wireless frame is confirmed not to be wirelessly received by another relay device, and the wireless LAN terminal is registered in the wireless table. If the wireless LAN terminal registered in the above is also registered in the wired table at the same time, a means for deleting the registration of the wireless LAN terminal from the wired table, and a case where a wired frame is received from the wired LAN terminal and the other from the wireless LAN terminal When a wired frame is received via a relay device, the wired LAN terminal or wireless LAN terminal A relay having a means for registering in the table and a means for deleting the registration of the wireless LAN terminal from the wireless table when the wireless LAN terminal registered in the wired table is simultaneously registered in the wireless table. apparatus. 7. The relay device according to claim 6, wherein a wireless frame received from a wireless LAN terminal is not received by another relay device, the wireless LAN terminal is set as a sender for a time period set with a random number. A relay device characterized by confirming that a wired frame is not transmitted. 8. The relay device according to claim 6, wherein, with respect to the wired table or the wireless table, a wireless LAN terminal and a wired LAN terminal that have not been registered, deleted, or checked for registration for a predetermined time or longer are deleted. A relay device comprising means for performing.