JP2585843B2 - Local area network interconnection device and station device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN interconnecting apparatus and a station apparatus for enabling communication between a plurality of local area networks (hereinafter referred to as LANs) in a data communication system. In particular, the present invention relates to an interconnecting device and a station device for relaying cells between LANs that perform packet communication using fixed-length cells.

2. Description of the Related Art In a LAN, a packet is divided into fixed-length data, a cell header is added to the data to form a fixed-length cell, and this cell is transmitted at a high speed so that communication between the station devices is performed. There is something that is.

When a plurality of such LANs are provided, in order to enable communication between station devices connected to each LAN, for example, IEICE technical report IN89-35
Discloses an interconnecting device that interconnects LANs and relays cells.

According to this type of interconnecting device, for example, as shown in FIG. 8, by connecting the LANs 61 and 62 having the station devices 64 and 65 by the interconnecting device 63, communication between the station devices 64 and 65 is performed. Can be performed.

The station devices 64 and 65 and the interconnecting device 63 have network addresses for efficiently communicating within the LAN and relaying at the interconnecting device 63 when these devices are incorporated into a network. Is set. This network address is composed of, for example, a 32-bit bit string, and is set in a hierarchical manner into two numerical values each of which indicates a network identification number, and two numerical values each of which indicate a station identification number in a network. ing.

In the example shown in FIG. 8, the station device 64 of the LAN 61 has a network address (10 · 0) composed of the network identification number (1 · 0) of the LAN 61 and the station identification number (0.1) of the station device 64.
0.0.1) is set. Also, the station device 6 of LAN62
5 has the same network address (20.0.0.0)
1) is set. On the other hand, the interconnection device 63 has LA
The network addresses (10.0.0.2), (20.0.0.0) are connected to the ports connected to N61 and N62, respectively.
2) is set.

The station devices 64 and 65 and the interconnecting device 63 are also provided with a medium access control address (hereinafter referred to as a different value) independent of the network configuration when each device is manufactured.
Called MAC address. ) Is set.

Further, the station device 64 is provided with a routing table 81 for determining a transmission route as shown in FIG. The routing table 81 includes a network identification number 82 of the LAN to which the station device of the communication partner is connected.
And a network address 83 of the interconnection device used for communication and an interface identification number 84 indicating a port of the own station are stored in advance. For example, when communicating with a station device connected to the LAN 61 with the network identification number (10.0), it is not necessary to use an interconnecting device, while the LAN 62 with the network identification number (20.0) is used.
When communicating with a station device connected to the network device, it is shown that the interconnection device 63 of the network address (10.0.0.2) is used. In each case, the interface identification number (10
.0.0.1) port is indicated to be used.

The routing table 81 also stores a MAC address (not shown) of each device.
The station device 65 also has the same routing table.

On the other hand, the interconnecting device 63 has a routing table 91 as shown in FIG. 10, for example, when relaying to a station device connected to the LAN 61, the interface identification number to which the LAN 61 is connected. While the port of (10.0.0.2) is used, the interface identification number (20.0.0.2) for the station connected to the LAN 62 is used.
Port is indicated to be used.

In the network system as described above, for example, data transmission from the station device 64 to the station device 65 is performed as follows.

For example, as shown in FIG.
A packet 700 is generated by adding a data link header 701 and a network header 704 to 707 based on the routing table 81.

The data link header 701 includes a destination address field (hereinafter, referred to as a DA field) 702 in which a MAC address is set in each of the direct-destination interconnection device 63 and the transmission-source station device 64, and a source address. Field (hereinafter, referred to as SA field) 703.

The network header 704 includes the network address (20.0.0.0) of the destination station device 65,
And the network address (10.
DA field 705 in which “0.0.1” is set, and SA
Consists of field 706.

Next, the packet is divided into fixed-length data of, for example, every 48 bytes, and each of the divided data is added with a cell header 711 as a payload 714.
Generate

The cell header 711 includes a virtual channel identifier (hereinafter, VCI)
Called. ) 712 and a message identifier (hereinafter referred to as MID) 713. The VCI 712 indicates whether the cell 710 is a cell in which a connectionless service or a connection-type service is performed. For example, in the case of a connectionless service in which communication by the above-described packet is performed, all bits are set to “1”. "Is set. In the case of the connection type service, a value indicating a logical channel established at the start of communication between any two-station device is set. Further, a value indicating which packet 700 the cell 710 was generated from is set in the MID 713, and the same value is set in the cells 710 generated from the same packet 700.

The cells 710 generated in this manner are sent out onto the transmission path of the LAN 61.

The interconnection device 63 includes all cells 71 transmitted through the transmission path.
Check the value of VCI 712 with respect to 0, and combine the payload 714 for each cell 710 with the same MID 713 for the cells 710 with all bits being "1" to restore the original packet 700. . Then, the packet 7 in which the MAC address of the interconnection device 63 is set in the DA field 702 of the data link header 701 in the restored packet 700
Only 00 is selected, and other packets 700 are discarded.

Next, the routing table 91 is referred to based on the network address (20.0.1.1) of the destination station device 65 set in the DA field 705 of the network header 704 in the selected packet 700, and Of the station device 65 is present in the LAN 62 connected to the interconnection device 63, and that the port to be used is the port of the interface identification number (20.0.0.2).

Therefore, the MAC address of the own device set in the DA field 702 of the data link header 701 in the restored packet 700 is deleted, and the MAC address of the destination station device 65 is replaced.
After setting the address, a connectionless cell 710... Similar to the cells 710... Transmitted from the station device 64 is generated based on the new packet, and the interface identification number (20.0.0.2) is set. ) Port to LAN62.

When the cell 710 is received, the station apparatus 65 restores the original packet and selects a packet in which the MAC address of the own apparatus is set in the DA field 702 as in the case of the interconnection apparatus 63, and transmits the transmission data 707. Receive.

As described above, the interconnecting device 63 relays the packet 700 based on the data link header 701 and the network header 704 of the packet 700, so that the station devices 64 and 65 connected to the different LANs 61 and 62 respectively. It was designed for data transmission.

However, in the above-described conventional local area network interconnecting device, it is determined whether or not it is necessary to relay the received cells 710 by the local area network interconnecting device. After restoring the packet 700, sensing of which LAN the station device is connected to is performed by the data link header 701 and the network header 704 of the packet 700.

Therefore, among the received cells 710 ..., the cell header 7
For all cells 710 that have been shown to perform connectionless services by 11 VCIs 712,
Packet 700 must be restored. In addition, it is necessary to change the data link header 701 of the restored packet 700 according to the destination station apparatus, and then generate a cell to be transmitted to the destination station apparatus again.

Therefore, the apparatus requires a complicated configuration, and the manufacturing cost is high. In addition, since the time required for relaying tends to be long, it is difficult to improve the transmission capacity.

The present invention has been made in view of the above circumstances, and has as its object to provide an interconnection device and a station device of a local area network having a simple configuration and capable of easily improving transmission capacity.

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 performs at least packet communication using fixed-length cells in which a packet is divided into fixed-length data and a cell header is added. In a local area network interconnecting device for relaying the cell between two local area networks, the cell is connected to a second local area network via a second interconnecting device based on a cell header of the cell transmitted in the first local area network. , The cell header of the cell is changed to a cell header indicating a destination device in the second local area network, and the cell whose cell header is changed is changed to the second local area network. Cell relay means for transferring to an area network ing.

The invention according to claim 2 is the interconnection apparatus for a local area network according to claim 1, wherein the cell relay means is transmitted over a first local area network, and is connected to a second local area. First transfer information set in a cell header of a cell transferred to the network;
Transfer information storage means for associating and storing second transfer information indicating a destination device of a cell in the second local area network, a cell header of a cell transmitted in the first local area network, and the transfer information Based on the first transfer information stored in the storage means,
Transfer cell detecting means for detecting that the cell is a cell transferred to the second local area network via the interconnection device; and a second cell stored in the transfer information storage means.
Cell header changing means for changing the cell header based on the transfer information.

According to a third aspect of the present invention, there is provided an interconnection device for a local area network according to the second aspect, wherein each of the station devices in the local area network includes:
Transfer necessity information request means for inquiring whether there is a need for cell transfer to another local area network, and transfer necessity information detection for detecting transfer necessity information transmitted from each station device in response to the request Means, and based on the transfer necessity information from each station device,
Transfer information processing means for storing the transfer information and the second transfer information in the transfer information storage means, and transmitting the first transfer information to at least the station apparatus which has transmitted the transfer necessity information. It is characterized by.

According to a fourth aspect of the present invention, there is provided an interconnection device for a local area network according to the second aspect, wherein the interconnection device is automatically transmitted from a station device in each local area network to another local area network. Transfer necessity information detecting means for detecting transfer necessity information indicating the necessity of cell transfer, and transfer information storage means for storing the first transfer information and the second transfer information based on the transfer necessity information. And a transfer necessity information processing means for transmitting the first transfer information to at least the station device which has transmitted the transfer necessity information.

The invention according to claim 5 is characterized in that, in a local area network station apparatus that performs packet communication by fixed-length cells in which a packet is divided into fixed-length data and a cell header is added, a cell header of a cell to be transmitted includes:
A transfer cell management means for setting transfer information indicating a cell to be transferred to another local area network via the interconnection device is provided.

According to a sixth aspect of the present invention, in a local area network station apparatus for performing packet communication using fixed length cells in which a packet is divided into fixed length data and a cell header is added, the packet is transmitted from the interconnection apparatus. ,
A transfer necessity information request for inquiring whether there is a need for cell transfer to another local area network, and a management cell detecting means for detecting transfer information set in a cell header of a cell transferred to another local area network,
In response to the transfer necessity information request, the transfer necessity information is transmitted to the interconnecting device, while the transfer information from the interconnecting device is stored, and the stored transfer information is set in a cell header of a cell to be transmitted. And a cell management means.

According to a seventh aspect of the present invention, there is provided a local area network station apparatus for performing packet communication using fixed-length cells in which a packet is divided into fixed-length data and a cell header is added. Transfer cell management means for transmitting transfer necessity information indicating the necessity of cell transfer to the interconnecting device, storing transfer information sent from the interconnecting device, and setting the stored transfer information in a cell header of a cell to be transmitted; And management cell detection means for detecting transfer information sent from the interconnecting device and outputting the information to the transfer cell management means.

According to the first aspect of the present invention, the cell relay means of the interconnection device, based on the cell header of the cell transmitted in the first local area network, allows the cell to pass through the second interconnection device via the interconnection device. Detecting that the cell is transferred to the local area network, changing the cell header of the cell to a cell header indicating a destination device in the second local area network, and replacing the cell with the changed cell header with the second local area Transfer to network.

According to the second aspect of the present invention, the transfer information storage means comprises:
First transfer information set in a cell header of a cell transmitted on the first local area network and transferred to the second local area network, and a second indicating a destination device of the cell in the second local area network Transfer cell detecting means, the transfer cell detecting means, based on a cell header of a cell transmitted in a first local area network and the first transfer information stored in the transfer information storing means, Detecting that the cell is a cell to be transferred to the second local area network via the interconnection device, the cell header changing means detects the cell header based on the second transfer information stored in the transfer information storage means. To change. The cell relay means,
The cell with the changed cell header is transferred to the second local area network.

According to the third aspect of the present invention, the transfer necessity information requesting means inquires of the station device in each local area network whether or not cell transfer to another local area network is necessary, and transmits the transfer necessity information. The detecting means detects the transfer necessity information sent from each of the station devices in response to the request, and the transfer necessity information processing means, based on the transfer necessity information from each of the station devices, The first transfer information and the second transfer information are stored in the transfer information storage means, and the first transfer information is transmitted to at least the station device that has transmitted the transfer necessity information.

According to the fourth aspect of the invention, the transfer necessity information detecting means is spontaneously transmitted from the station device in each local area network. Transfer necessity information indicating the necessity of cell transfer to another local area network is detected, and the transfer necessity information processing means performs the first transfer information and the second transfer information based on the transfer necessity information. The transfer information is stored in the transfer information storage means, and the first transfer information is transmitted to at least the station device that has transmitted the transfer necessity information.

According to the fifth aspect of the present invention, the transfer cell management means includes:
In the cell header of the cell to be transmitted, transfer information indicating that the cell is transferred to another local area network via the interconnection device is set.

According to the invention of claim 6, the management cell detecting means includes:
A transfer necessity information request for inquiring whether or not cell transfer to another local area network is required, which is sent from the interconnecting device, and transfer information to be set in a cell header of a cell to be transferred to another local area network. In response to the transfer necessity information request, the transfer cell management means transmits the transfer necessity information to the interconnecting device, while storing the transfer information from the interconnecting device, and in a cell header of a cell to be transmitted, The stored transfer information is set.

According to the seventh aspect of the present invention, the transfer cell management means includes:
While transferring the transfer necessity information indicating the necessity of cell transfer to another local area network to the interconnecting device, the transfer information sent from the interconnecting device is stored, and the stored transfer information is stored in the cell header of the cell to be transmitted. Is set, and the management cell detection means detects the transfer information transmitted from the interconnecting device and outputs the transfer information to the transfer cell management means.

1. Embodiment FIG. 1 is an explanatory diagram showing a configuration of a LAN system to which a LAN interconnection device 300 and station devices 110 and 210 according to an embodiment of the present invention are applied, and FIG. 2 shows a configuration of the interconnection device 300. FIG. 3 is a block diagram showing the configuration of the station device 110 (210), FIG. 4 is an explanatory diagram showing the structure of the cell 400,
FIG. 5 is an explanatory diagram showing an example of a correspondence table stored in the transfer information storage means 304 of the interconnection device 300.

In FIG. 1, 100 and 200 are LANs, 101 and 201 are transmission lines, 110 and 210 are station devices connected to the transmission lines 101 and 201, respectively, and 300 is an interconnection device connecting the LAN 100 and the LAN 200. is there.

In FIG. 2, reference numerals 301 and 302 denote access control means, 303
Is cell relay means, 304 is transfer information storage means, 305 and 306 are transfer cell detection means, 307 is cell header change means, 308 and 30
Reference numeral 9 denotes transfer necessity information request means, 310 and 311 denote transfer necessity information detection means, and 312 denotes transfer necessity information processing means.

In FIG. 3, 111 (211) is a keyboard and a mouse,
Input means such as a data processing device; 112 (212) packet generation means; 113 (213) cell generation means; 114 (214) access management means; 115 (215) self-addressed cell detection means;
(216) is a packet restoration means, 117 (217) is a packet decoding means, 118 (218) is an output means such as a display, a printer, a data processing device, etc., 119 (219) is a management cell detection means, and 120 (220) is a transfer. It is a cell management means.

In FIG. 4, 400 is a cell, 401 is a cell header, 402
Is VCI, 403 is MID, and 404 is payload.

Access management means 301 in the interconnection device 300,
302 captures empty cells transmitted on the transmission paths 101 and 201, respectively, and transmits cells 400 including transmission data and the like, and receives the cells 400 transmitted from the station devices 110 and 210. I have.

For example, as shown in FIG. 5, the transfer information storage means 304 stores the values 501 and 50 of the VCI 402 set in the LANs 100 and 200 in the cell 400 relayed by the interconnection device 300, respectively.
2, and a peer table 500 in which the identification numbers 503, 504, etc. of the respective station devices are stored. Fifth
In the example of the correspondence table 500 shown in the figure, the value of the VCI 402 of the cell 400 transmitted between the station device 110 and the station device 210 is LAN 100, 200
It is shown that “A1” and “A2” are set respectively in FIG.

The transfer cell detecting means 305 and 306 are used for the LANs 100 and 20 respectively.
Based on the VCI 402 of the cell 400 received from 0 and the correspondence table 500, it is determined whether or not the cell 400 is a cell relayed via the interconnection device 300.

The cell header changing means 307 changes the VCI 402 of the cell 400 to be relayed based on the correspondence table 500.

The transfer necessity information requesting means 308, 309 generates a search cell 610, which will be described later, and sends the other LAN 100, 200 to the station device 110, 210.
Transfer necessity information indicating whether or not the cell 400 needs to be transferred.

The transfer necessity information detecting means 310 and 311
Search response cell 620 from 110, 210, and relay request cell 6
The transfer necessity information is detected based on 60.

The transfer necessity information processing means 312 stores the correspondence table 5 stored in the transfer information storage means 304 based on the transfer necessity information.
As well as creating a 00, a notification cell 630, a relay request response cell 670, and a relay request notification cell 680, which will be described later, are generated.

On the other hand, the packet generation means 112 in the station device 110 generates a packet by adding a header to data input from the input means 111 and transmitted to another station device 210 or the like.

The cell generation means 113 divides the packet into fixed-length data of, for example, every 48 bytes, and adds a cell header 401 as each of the divided data as a payload 404,
A cell 400 is generated.

The access management unit 114 captures an empty cell transmitted on the transmission line 101, transmits the cell 400, and receives the cell 400 transmitted from the interconnection device 300 or another station device. .

The self-station-destined cell detection means 115 selects a cell 400 addressed to the self-station from the cells 400 received by the access management means 114.

The packet restoring means 116 restores the original packet based on the selected cell 400.

The packet decoding means 117 decodes the restored packet, restores the data transmitted to the station device 110, and outputs
Output to 18

The management cell detecting means 119 includes, among the cells 400 received by the access managing means 114, the search cell 610, the notification cell 630, the relay request response cell 670,
And the relay request notification cell 680 is selected and output to the transfer cell management means 120.

The transfer cell management unit 120 generates a search response cell 620 or a relay request cell 660 based on the search cell 610 transmitted from the interconnecting device 300 or an instruction from the input unit 111, and Transmitted notification cell 630, relay request response cell 670, or relay request notification cell
Based on 680, a correspondence table 500 similar to the interconnection device 300 is created and held. In addition, the above correspondence table 50
0, the cell generation unit 113 or the own-station-directed cell detection unit 115 generates a cell to be transmitted through the interconnecting device 300, or generates a cell to be transmitted to the own station transmitted through the interconnecting device 300. It is designed to instruct detection.

The station device 210 has a configuration similar to that of the station device 110.

In the above configuration, for example, the station device 110 to the station device 210
When data is transmitted to the station devices 110 and 210 and the interconnecting device 300, the following operation is performed.

First, the packet generation means 112 of the station device 110
Generate a packet based on the data input from 1. The cell generation unit 113 divides the packet into data of a fixed length every 48 bytes, adds a cell header 401 as a payload 404 to each of the divided data, and
Generate 404. Here, in the VCI 402 of the cell header 401, a value “A1” indicating that the cell is to be relayed to the LAN 200 via the interconnecting device 300 based on the correspondence table 500 stored in the transfer cell management means 120. Is set. Also, a value indicating that the cell is generated from the same packet is set in each MID 403. Access control means
114 sends the generated cell 400 to the transmission path 101.

The access management means 301 of the interconnection device 300
The cell 400 transmitted from 0 is received. Transfer cell detection means
305 is a cell to be transferred to the station device 210 of the LAN 200 based on the value “A1” of the VCI 402 in the received cell 400 and the correspondence table 500 stored in the transfer information storage means 304 Is detected.

The cell header changing unit 307 sets the value of the CVI 402 to “A2” based on the detection result of the transfer cell detecting unit 305 and the correspondence table 500.
Change to The access management means 302 sends the cell 400 in which the value of the VCI 402 has been changed to the transmission line 201 of the LAN 200.

The access management means 214 of the station device 210
The cell 400 transferred by 0 is received. The cell detection unit 215 for the own station receives the value “A
Based on 2 "and the correspondence table 500 stored in the transfer cell management means 220, it is detected that the cell 400 is a cell transferred to its own station via the interconnection device 300, and the packet recovery means 216 The self-addressed cell detection means 215 also outputs to the packet restoration means 216 when the received cell 400 is a connectionless cell and when the received cell 400 is a connection-type cell addressed to the own station. I do.

The packet restoration unit 216 combines the payload 404 for each cell 400 having the same value of the MID 403 and restores the packet.

The packet decoding means 117 performs processing such as packet identification and error correction based on the header of the restored packet, restores the original data, and outputs the original data to the output means 118.

By the way, the transfer cell management means 12 of the station devices 110 and 210
0, 220, and the transfer information storage means 304 of the interconnect device 300
The correspondence table 500 stored in may be set in advance for each device, or may be set based on the request of the interconnecting device 300 or the station devices 110 and 210 as follows. You may make it.

First, an example in which the correspondence table 500 is set based on a request from the interconnecting device 300 will be described with reference to FIGS. 6 (a) to 6 (c) show the structure of a search cell 610, a search response cell 620, or a notification cell 630 as a management cell transmitted and received between the station devices 110 and 210 and the interconnection device 300, respectively. FIG.

6 (a) to 6 (c), reference numerals 611, 621, 631 denote cell headers, 612, 622, 632 denote VCIs, 613, 623, 633 denote payloads, 614, 624, 634 denote type fields, 615, 626,
Reference numeral 637 denotes padding for setting the cell length to a fixed length of, for example, 53 bytes, 625 denotes a local station device identification number field, 635 denotes a destination station device identification number field, and 636 denotes a notification VCI field.

Transfer necessity information request means 308, 309 of the interconnecting device 300
Generates a search cell 610 that requests transmission of transfer necessity information by searching for a station device that needs to perform transmission via the interconnection device 300, for example, at the time of device initialization.

In the VCI 612 of the cell header 611 in the search cell 610, a value indicating that the cell is a broadcast cell addressed to all station devices is set. In the type field 614 of the payload 613, a value indicating a search cell is set. The access management means 301 and 302 transmit the generated search cell 610 to the transmission lines 101 and 201 of the LANs 100 and 200. The management cell detection means 119 of the station device 110 determines that the cell received by the access management means 114 is the search cell. When the search cell 610 is detected as the transfer cell management means 1
Output to 20.

If the transfer cell management unit 120 determines that it is necessary to perform transmission with the station device of the LAN 200 via the interconnection device 300 based on the information and the like from the input unit 111, the transfer necessity information A search response cell 620 is generated.

VCI 622 of cell header 621 in the search response cell 620
Is set to a value indicating that the cell is addressed to the interconnection device 300. Also, type field 6 of payload 623
24, and the own station apparatus identification number field 625 contain a value indicating that the cell is a search response cell and the station apparatus, respectively.
110 station device identification numbers are set. Access control means 1
14 sends the search response cell 620 to the transmission line 101.

When the transfer necessity information detecting means 310 of the interconnecting device 300 detects that the cell received by the access managing means 301 is the search response cell 620, the search response cell 6
20 is output to the transfer necessity information processing means 312.

The transfer necessity information processing means 312 determines the value of the VCI used in the LANs 100 and 200 for the cells transmitted to and from the station device 110 that has transmitted the search response cell 620 for every destination station device in the LAN 200. , A correspondence table 500 is created. Also,
A notification cell 630 for notifying the station device 110 of the VCI value is generated.

In the VCI 632 of the cell header 631 in the notification cell 630, a value indicating that the cell is addressed to the station device 110 is set. The type field 634 of the payload 633, the destination station apparatus identification number field 635, and the notification VCI field 636 respectively contain a value indicating a notification cell, the identification number of the destination station apparatus, and the destination station. A VCI value corresponding to the device is set. Access management means 301
Sends the notification cell 630 to the transmission path 101.

When detecting that the cell received by the access management unit 114 is the notification cell 630, the management cell detection unit 119 of the station device 110 transmits the notification cell 630 to the transfer cell management unit 1
Output to 20. The transfer cell management unit 120 creates the correspondence table 500 based on the notification cell 630.

Also, when the search device 610 is transmitted from the interconnecting device 300 and the station device 210 also needs to perform transmission with the station device of the LAN 100, similarly, the search response cell 620 is transmitted and the station device 210 transmits the search response cell 620. The correspondence table 500 is created in the transfer cell management means 220 of 210 and the transfer information storage means 304 of the interconnection device 300.

Next, an example in which the correspondence table 500 is set based on a request from the station device 110 will be described with reference to FIGS. 1 to 5 and FIG. FIGS. 7A to 7C are explanatory diagrams showing the structure of a relay request cell 660, a relay request response cell 670, or a relay request notification cell 680, which are management cells, respectively.

7A to 7C, reference numerals 661, 671, and 681 denote cell headers, 662, 672, and 682 denote VCIs, 663, 673, and 683 denote payloads, 664, 674, and 684 denote type fields, and 665 denotes a destination station. The device identification numbers 666, 676, and 687 indicate the cell length, for example, 53.
Padding to a fixed length of bytes, 675 is the notification VCI
A field 685 is a relay requesting station apparatus identification number field, and 686 is a notification VCI field.

The transfer cell management unit 120 of the station device 110 requests the interconnect device 300 to relay cells when it becomes necessary to perform mutual transmission with the station device 210 via the interconnect device 300, for example. A relay request cell 660 is generated.

VCI 662 of the cell header 661 in the relay request cell 600
Is set to a value indicating that the cell is transmitted from the station device 110 to the interconnection device 300. Payload 663
The type field 664 and the destination station apparatus identification number field 665 respectively contain a value indicating that the cell is a relay request cell, and the destination station apparatus 21 to be transmitted.
A station device identification number of 0 is set. Access management means 114
Sends out the generated relay request cell 660 to the transmission line 101.

When the transfer necessity information detecting means 310 of the interconnecting device 300 detects that the cell received by the access
60 is output to the transfer necessity information processing means 312.

The transfer necessity information processing means 312 includes a LAN 100, 200 in a cell transmitting between the station device 110 which is a relay requesting station device and the station device 210 indicated by the destination station device identification number field 665 of the relay request cell 660. Determine the value of the VCI used within
Create the correspondence table 500. In addition, the value of the VCI is
A relay request response cell 670 for notifying 0 and 210 and a relay request notification cell 680 are generated.

VC of cell header 671 in relay request response cell 670
In I672, a value indicating that the cell is transmitted from the interconnection device 300 to the station device 110 is set. Also the payload
673 type field 674 and notification VCI field 6
In 75, a value indicating that the cell is a relay request response cell and a value of the VCI used for the cell transmitted from the station device 110 to the station device 210 are set.

On the other hand, the cell header 681 in the relay request notification cell 680
In the VCI 682, a value indicating that the cell is transmitted from the interconnection device 300 to the station device 210 is set. The type field 684 of the payload 683, the relay request station apparatus identification number field 685, and the notification VCI field 686 each include a value indicating that the cell is a relay request notification cell,
A station device identification number of 110 and a CVI value used for a cell transmitted from the station device 210 to the station device 110 are set.

The access management means 301 sends these cells to the transmission lines 101 and 201, respectively.

The management cell detection means 119 of the station device 110 determines that the cell received by the access management means 114 is the relay request response cell 670.
Is detected, the relay request response cell 670 is output to the transfer cell management means 120. Transfer cell management means 120
Creates the correspondence table 500 based on the relay request response cell 670.

When detecting that the cell received by the access management unit 214 is the relay request notification cell 680, the management cell detection unit 219 of the station device 210 outputs the relay request notification cell 680 to the transfer cell management unit 220. . The transfer cell management means 220, based on the relay request notification cell 680,
Create

It should be noted that, based on the request of the interconnection device 300, the correspondence table 5
In the example in which 00 is set, the value of the VCI used for the cell transmitted between the station device 110 and all the station devices in the LAN 200 is determined, while the correspondence table 5 is determined based on the request of the station device 110.
In the example in which 00 is set, an example has been described in which only the value of the VCI used for the cell transmitted between the destination station device 210 specified by the station device 110 is determined, but in the former example, Only the VCI value for the destination station device specified by the station device 110 may be determined, or in the latter example, the VCI values for all the station devices in the LAN 200 may be determined. .

In the former example, the determined VCI value is transmitted only to the station device 110, while in the latter example, the transmitted VCI value is also transmitted to the station device 210. However, the present invention is not limited to each example. That is, if only one-way transmission from the station device 110 is sufficient, the value of CVI is not transmitted to the station device 210, but if bidirectional transmission is required, the value is also transmitted to the station device 210. do it.

Further, the value of the VCI transmitted by one management cell is not limited to one, and a plurality of values may be transmitted collectively.

The source and destination devices of the management cell are not limited to those indicated by the VCI, but may be indicated by data in the payload, and the VCI may simply indicate that the cell is a management cell, or Alternatively, the type field may be omitted by indicating the type of the management cell by the VCI.

Further, in the present embodiment, the ring type LANs 100, 20
Although the example of connecting 0 by the interconnect device 300 has been described,
The present invention is not limited to this, and can be applied to various types of LANs as long as the LAN transmits cells of the same type.

Also, an example in which the two LANs 100 and 200 are connected by one interconnecting device 300 has been described.
May be connected by a single interconnecting device, or a plurality of LANs may be connected via a plurality of interconnecting devices.

Further, the detection of the transfer cell by the transfer cell detecting unit 305 of the interconnecting device 300 and the change of the cell header by the cell header changing unit 307 are not limited to those based on the correspondence table 500 stored in the transfer information storage unit 304, and include, for example, The VCI value may be detected by a decoder, and the cell header may be changed by an encoder, a bit inversion circuit, or the like.

Effect of the Invention As described above, according to the first and second aspects of the present invention, based on the cell header of a cell transmitted in the first local area network, the cell is connected via the interconnection device. Detecting that the cell is a cell transferred to the second local area network, changing the cell header of the cell to a cell header indicating a destination device in the second local area network, and replacing the cell with the changed cell header with the second cell Is provided, a cell can be relayed without restoring the cell into a packet or generating a cell again.

Therefore, the processing performed by the device can be reduced.
It is possible to simplify the configuration of the device, reduce the manufacturing cost, and shorten the time required for relaying, thereby easily improving the transmission capability.

According to the third aspect of the present invention, transfer necessity information requesting means for inquiring the station device in each local area network whether cell transfer to another local area network is necessary, and responding to the request. A transfer necessity information detecting means for detecting transfer necessity information sent from each of the station devices; and a second local area network which transmits the transfer necessity information based on the transfer necessity information from each of the station devices. The first transfer information set in the cell header of the cell transferred to the local area network and the second transfer information indicating the destination and the device of the cell in the second local area network are stored in the transfer information storage means. Transfer necessity information for transmitting the first transfer information to at least the station device that has transmitted the transfer necessity information By and a stage, since only the information required for the transfer of the cell is automatically set,
The storage capacity required for storing the above information can be reduced, and it is possible to flexibly cope with a change in the connection structure of the local area network.

According to the fourth aspect of the present invention, it is necessary to detect the transfer necessity information, which is spontaneously transmitted from the station device in each local area network and indicates the necessity of cell transfer to another local area network. Gender information detecting means, and the first transfer information and the second transfer information are stored in transfer information storage means based on the transfer necessity information, and at least the By providing the transfer necessity information processing means for transmitting the first transfer information, only the information necessary for the cell transfer is set when the cell transfer is required in each station device. It is said that the storage capacity required for storing the above information can be reduced, and it is possible to flexibly cope with a change in the necessity of cell transfer in the station device. Achieve the results.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a local area network system to which a local area network interconnection device and a station device according to an embodiment of the present invention are applied;
FIG. 2 is a block diagram showing the configuration of the interconnection device, FIG. 3 is a block diagram showing the configuration of the station device, FIG. 4 is an explanatory diagram showing the structure of the cell, and FIG. FIGS. 6A to 6C show examples of correspondence tables stored in the means and the transfer cell management means of the station device, and FIGS. 6A to 6C show structures of a search cell, a search reply cell, and a notification cell, respectively. FIGS. 7 (a) to 7 (c) are explanatory diagrams showing the structure of a relay request cell, a relay request response cell, or a relay request notification cell, respectively, and FIG. 8 is a conventional local area network interconnection. FIG. 9, FIG. 9, and FIG. 10 are diagrams illustrating a configuration of a local area network system to which a device and a station device are applied, respectively. FIG. packet FIG. 3 is an explanatory diagram showing the structure of a cell. 100, 200 …… Local area network, 110, 210…
... station devices, 111, 211 ... input means, 112, 212 ... packet generation means, 113, 213 ... cell generation means, 114, 214 ...
Access management means, 115, 215 ... self-station-addressed cell detection means,
116, 216: Packet recovery means, 117, 217: Packet decoding means, 118, 218 ... Output means, 119, 219 ... Management cell detection means, 120, 220 ... Transfer cell management means, 300 ...
Interconnection devices, 301, 302 ... access management means, 303 ...
... Cell relay means, 304 ... Transfer information storage means, 305, 306
…… Transfer cell detecting means, 307 …… Cell header changing means, 3
08, 309 transfer necessity information request means, 310, 311 transfer necessity information detection means, 312 transfer necessity information processing means

Claims (7)

(57) [Claims] 1. An interconnection of a local area network for relaying a cell between at least two local area networks for performing packet communication by a fixed length cell in which a packet is divided into fixed length data and a cell header is added. The apparatus detects, based on a cell header of a cell transmitted on a first local area network, that the cell is a cell transferred to a second local area network via an interconnecting device, A local area network having cell relay means for changing the cell header to a cell header indicating a destination device in the second local area network and transferring the cell with the changed cell header to the second local area network. Interconnect equipment. 2. The cell relay means includes: first transfer information set in a cell header of a cell transmitted on a first local area network and transferred to a second local area network; Transfer information storage means for associating and storing second transfer information indicating a destination device of a cell in the area network; a cell header of a cell transmitted in the first local area network; and the transfer information storage means Transfer cell detecting means for detecting, based on the first transfer information, that the cell is a cell transferred to a second local area network via an interconnecting device; Cell header changing means for changing the cell header based on the second transfer information. Interconnect device local area network as set forth in claim 1, wherein claims. 3. The local area network interconnection device according to claim 2, wherein the transfer device inquires the station device in each local area network whether it is necessary to transfer cells to another local area network. Necessity information requesting means, in response to the request, transfer necessity information detecting means for detecting transfer necessity information transmitted from each station device, based on the transfer necessity information from each station device, Transfer necessity information processing means for storing the first transfer information and the second transfer information in transfer information storage means, and transmitting the first transfer information to at least a station device which has transmitted the transfer necessity information; An interconnection device for a local area network, comprising: 4. The local area network interconnection device according to claim 2, wherein a cell transfer to another local area network, which is spontaneously transmitted from a station device in each local area network, is required. Transfer necessity information detecting means for detecting transfer necessity information indicating the nature of the transfer, the first transfer information based on the transfer necessity information,
And transfer necessity information processing means for storing the second transfer information in the transfer information storage means and transmitting the first transfer information to at least the station apparatus which has transmitted the transfer necessity information. Local area network interconnection equipment. 5. A local area network station apparatus for performing packet communication using fixed-length cells in which a packet is divided into fixed-length data and a cell header is added. A transfer cell management means for setting transfer information indicating that the cell is transferred to another local area network. 6. A local area network station apparatus for performing packet communication using fixed-length cells, in which a packet is divided into fixed-length data and a cell header is added, is transmitted from an interconnecting apparatus to another local area. Management cell detecting means for detecting a transfer necessity information request for inquiring whether or not cell transfer to the network is necessary, and transfer information set in a cell header of a cell transferred to another local area network; Transfer cell management means for transmitting the transfer necessity information to the interconnecting device in response to the information request, storing the transfer information from the interconnecting device, and setting the stored transfer information in a cell header of a cell to be transmitted; A station device for a local area network, comprising: 7. Necessity of cell transfer to another local area network in a local area network station apparatus for performing packet communication by a fixed length cell in which a packet is divided into fixed length data and a cell header is added. Transfer necessity information indicating transmission necessity to the interconnecting device, while storing transfer information sent from the interconnecting device and setting the stored transfer information in a cell header of a cell to be transmitted; And a management cell detection means for detecting transfer information sent from the control cell and outputting the transfer information to the transfer cell management means.