JPH0456546A - Interconnection device and station equipment for local area network - Google Patents

Abstract

PURPOSE:To improve the transmission capability with simple constitution by detecting a cell to be a cell to be transferred based on a cell header of the cell, revising the cell header to a cell header representing an equipment of a destination and transferring the resulting cell. CONSTITUTION:An access management means 301, e.g. of an interconnection device 300 receives a cell sent from a station equipment 110 and a transfer cell detection means 305 detects it that the cell is a cell transferred to a station equipment 210 of a LAN 200 based on the cell header and a cross reference list stored in a transmission information storage means 304, A cell header revision means 307 revises the cell header based on the result of detection and the cross reference list and an access management means 302 sends further the cell to a transmission line 201 of the LAN 200. Since the processing required for the equipment is reduced, the constitution of the equipment is simplified and the time required for relay is decreased to improve the transmission capability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a LAN interconnection device and station device that enable mutual communication between a plurality of local area networks (hereinafter referred to as LAN) in a data communication system. In particular, the present invention relates to an interconnection device and a station device that relay cells between LANs that perform packet communication using fixed-length cells.

Conventional LAN technology involves dividing a packet into fixed-length data, adding a cell header to it to form fixed-length cells, and transmitting these cells at high speed to communicate between station equipment. There are some that are.

When multiple such LANs are provided, in order to enable communication between station devices connected to each LAN, for example, the Institute of Electronics, Information and Communication Engineers Technical Research Report 1N3
As disclosed in No. 9-35, an interconnection device is used to interconnect LANs and relay cells.

According to this type of interconnection device, for example, as shown in FIG. 8, a LAN 61.
By connecting 62 with an interconnection device 63, communication can be performed between the station devices 64 and 65.

The station equipment 64, 65 and the interconnection equipment 63 include:
When these devices are incorporated into a network, network addresses are set to ensure efficient communication within the LAN and relaying at the interconnection device 63. This network address consists of, for example, a 32-bit bit string, and is set in a hierarchical manner into two numbers for each 8 bits that represent a network identification number and two numbers for each 8 bits that represent a station identification number within the network. ing.

In the example shown in FIG. 8, the station device 64 of the LAN 61 includes L
A network address (10.0.0.1) consisting of the network identification number (10.0) of the AN 61 and the station identification number (0.1) of the station device 64 is set. Similarly, a network address (20.0.0.1) is set in the station device 65 of the LAN 62. on the other hand,
The interconnection device 63 has a network address (10
・0.0.2), (20.0.0.2) are set.

The station devices 64, 65 and the interconnect device 63 are also provided with medium access control addresses (medium access control addresses) with mutually different values unrelated to the network configuration at the time of manufacturing each device.
Hereinafter, it will be referred to as a MAC address. ) is set.

Furthermore, the station device 64 is equipped with a routing table 81 for determining transmission routes, as shown in FIG. This routing table 81 includes the network identification number 82 of the LAN to which the communication destination station device is connected, the network address 83 of the interconnection device used for communication, and the ink face identification number indicating the port of the own station. The number 84 is stored in advance.

For example, LAN61 with network identification number (10.0)
When communicating with a station device connected to LAN 62 with network identification number (20.0), there is no need to use an interconnection device. Address (10.0.0
- The use of the interconnection device 63 of 2) is now shown. Also, in either case, it is indicated that the port with the interface identification number (10.0.0.1) of the own station is to be used.

The routing table 81 further stores MAC addresses (not shown) of each device. Further, the station device 65 also includes a similar routing table.

On the other hand, the interconnection device 63 includes a routing table 91 as shown in FIG.
61 is connected to the interface identification number (10.
0, 0, 2), while the station equipment connected to LAN62 is now shown to use the port with the interface identification number (20, 0, 0, 2). ing.

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

For example, as shown in FIG. 11, the station device 64 adds a data link header 701 and a network header 70 to the transmission data 707 based on the routing table 81.
4 is added to generate packet 700.

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

In addition, the network header 704 contains the network address (20.0.0.1) of the destination station device 65, respectively.
), and the DA field 70 in which the network address (10.0.0.1) of the transmission source station device 64 is set.
5, and an SA field 706.

Next, the above packet is divided into fixed-length data of, for example, 48 bytes, each divided data is treated as a payload 714, a tag 711 is added to the cell, and a cell 10 is added to the cell. generate.

The above cell header 711 contains a virtual channel identifier (hereinafter referred to as V
It is called CI. ) 712 and a message identifier (hereinafter referred to as M
It is called ID. )713. VCI712 is
Indicates whether the cell 10 is a cell in which a connectionless service or a connection-oriented service is provided. For example, in the case of a connectionless service in which communication is performed using packets, all bits are set to “
1"' is set. In the case of a connection-oriented service, a value indicating a logical channel established at the start of communication between any two station devices is set. Also, MID
713, a value indicating from which packet 700 the self 10 was generated is set, and if the same packet 70
The same value is set for the self 10 generated from 0.

The self 10... generated in this way is connected to the LAN
61 transmission path.

The interconnection device 63 checks the value of the VCI 712 for all the self 10... transmitted through the transmission path, and selects the self 10... for which all bits are "1".
Regarding self 10 with the same MID713...
・Synthesizes the payload 714 for each of the original packets 70
Restore 0. Then, the DA field 702 of the data link link 701 in the restored packet 700
, select only the packet 700 in which the MAC address of the interconnection device 630 is set, and select the other packets 70.
0 is discarded.

Next, the network address (20.0.
0 and 1), and confirms that the destination station device 65 exists in the LAN 62 connected to the interconnection device 63, and that the port to be used has the interface identification number (20-0 -0.2) port.

Therefore, after deleting the own device's MAC address set in the DA field 702 of the data link header 701 in the restored packet 700 and setting the MAC address of the destination station device 65 instead, this new packet Based on the connectionless self 10 similar to the self 10 sent from the station device 64,
..., and the interface identification number (20.0.0
- Send to LAN62 from port 2).

When the station device 65 receives the self 10, it restores the original packet in the same way as the interconnection device 63, selects the packet in which the MAC address of the station device is set in the DA field 702, and transmits the transmission data 707. I will take it.

In this way, the interconnection device 63 includes the data link header 701 and the network header 7 of the packet 700.
By relaying the packet 700 based on
Data could be transmitted between station devices 64 and 65 connected to different LANs 61 and 62, respectively.

Problems to be Solved by the Invention However, in the above-mentioned conventional local area network interconnection device, it is difficult to determine whether or not the received self 10 needs to be relayed by the local area network interconnection device, and to send it. Which L is the destination station equipment?
After the packet 700 is restored, the information as to whether it is connected to the AN is determined by the data link header 701 and network header 704 of the packet 700.

For this purpose, it is necessary to restore the packet 700 for all of the received cells 10 . Furthermore, after changing the data link header 701 of the restored packet 700 according to the destination station device, it is necessary to generate a cell again to be sent to the destination station device.

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

In view of the above points, it is an object of the present invention to provide a local area network interconnection device and station device that have a simple configuration and can easily improve transmission capacity.

Means for Solving the Problems In order to achieve the above object, the invention as set forth in claim 1:
A local area network interconnection device that relays cells between at least two local area networks that perform packet communication using fixed-length cells in which a packet is divided into fixed-length data and a cell header is added. Based on the cell header of the cell transmitted in the first local area network, it is detected that the cell is a cell to be transferred to the second local area network via the interconnection device, and the cell header of the cell is transferred to the second local area network. The present invention is characterized by comprising cell relay means for changing the cell header to indicate a destination device in the second local area network and transferring the cell with the changed cell header to the second local area network.

The invention as set forth in claim 2 is the local area network interconnection device as set forth in claim 1, wherein the cell relay means includes a cell that is transmitted in a first local area network, and a cell that is transmitted in a second local area network. Transfer information storage means for storing first transfer information set in a cell header of a cell transferred to the network and second transfer information indicating a destination device of the cell in a second local area network in a corresponding manner; Based on the cell header of the cell transmitted in the first local area network and the first forwarding information stored in the forwarding information storage means, the cell is forwarded to the second local area network via the interconnection device. a cell header change means for changing the cell header based on the second transfer information stored in the transfer information storage means. There is.

The invention set forth in claim 3 is the interconnection device for local area networks set forth in claim 2, wherein the station equipment in each local area network is provided with the need for cell transfer to another local area network. transfer necessity information requesting means for inquiring about the presence or absence of transfer necessity information; transfer necessity information detection means for detecting transfer necessity information sent from each station device in response to the request; and transfer necessity information detecting means for detecting transfer necessity information sent from each station device in response to the request; a transfer necessity that causes the first transfer information and the second transfer information to be stored in a transfer information storage means based on the information, and at least conveys the first transfer information to the station device that has transmitted the transfer necessity information; It is characterized by being equipped with an information processing means.

The invention as set forth in claim 4 is an interconnection device for local area networks as set forth in claim 2, which transmits information spontaneously from a station device in each local area network to another local area network. a transfer necessity information detection means for detecting transfer necessity information indicating the necessity of cell transfer; and a transfer information storage means for storing the first transfer information and the second transfer information based on the transfer necessity information. The present invention is characterized by comprising a transfer necessity information processing means for storing the first transfer information and transmitting the first transfer information to at least the station device that has transmitted the transfer necessity information.

The invention as set forth in claim 5 provides, in a local area network station device that performs packet communication using 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 sent; The present invention is characterized by comprising a transfer cell management means for setting transfer information indicating that the cell is transferred to another local area network via an interconnection device.

The invention as set forth in claim 6 is directed to a station device of a local area network that performs packet communication using fixed-length cells in which a packet is divided into fixed-length data and a cell header is added, and is transmitted from an interconnection device. , a management cell detection means for detecting a transfer necessity information request that inquires as to whether there is a need for cell transfer to another local area network, and transfer information to be set in a cell header of a cell transferred to another local area network; , in response to the transfer necessity information request, transmitting the transfer necessity information to the interconnection device, storing the transfer information from the interconnection device, and setting the stored transfer information in the cell header of the cell to be transmitted. The present invention is characterized by comprising a transfer cell management means.

The invention as set forth in claim 7 is a station device of a local area network that performs packet communication using fixed-length cells in which packets are divided into fixed-length data and cell headers are added. Transfer cell management means that transmits transfer necessity information indicating the necessity of cell transfer to the interconnection device, stores transfer information sent from the interconnection device, and sets the stored transfer information in the cell header of the cell to be sent. and management cell detection means for detecting transfer information sent from the interconnection device and outputting it to the transfer cell management means.

According to the invention set forth in claim 1, the cell relay means of the interconnection device transmits the cell to the second local area network via the interconnection device based on the cell header of the cell transmitted in the first local area network. detects that the cell is to be transferred to a local area network, changes the cell header of the cell to a cell header indicating a destination device in a second local area network, and transfers the cell with the changed cell header to the second local area network. Transfer to network.

According to the invention of claim 2, the transfer information storage means stores the first transfer information set in the cell header of the cell transmitted in the first local area network and transferred to the second local area network. , and second forwarding information indicating a destination device of the cell in the second local area network, and the forwarding cell detecting means stores a cell header of a cell transmitted in the first local area network, and second forwarding information indicating a destination device of the cell in the second local area network. Based on the first transfer information stored in the transfer information storage means, the cell header modification means detects that the cell is a cell to be transferred to the second local area network via the interconnection device; The cell header is changed based on the second transfer information stored in the information storage means. The cell relay means transfers the cell whose cell header has been changed to the second local area network.

According to the invention set forth in claim 3, the transfer necessity information requesting means inquires of the station equipment in each local area network whether there is a need for cell transfer to another local area network, and requests the transfer necessity information. The detection means detects transfer necessity information sent from each station device in response to the request, and the transfer necessity information processing means detects transfer necessity information sent from each station device, based on the transfer necessity information from each station device.
The first transfer information and the second transfer information are stored in a transfer information storage means, and the first transfer information is transmitted to at least the station device that sent the transfer necessity information.

According to the invention of claim 4, the transfer necessity information detecting means detects the necessity of cell transfer to another local area network, which is spontaneously transmitted from the station equipment in each local area network. Detecting transfer necessity information indicating transfer necessity information, the transfer necessity information processing means stores the first transfer information and the second transfer information in the transfer information storage means based on the transfer necessity information, and The first transfer information is transmitted to at least the station device that sent the transfer necessity information.

According to the invention of claim 5, the transfer cell management means includes transfer information in the cell header of the cell to be sent, indicating that the cell is a cell to be transferred to another local area network via an interconnection device. According to the invention set forth in claim 6, the management cell detection means receives a transfer necessity information request sent from the interconnection device, inquiring whether cell transfer to another local area network is necessary, and other information. The transfer cell management means detects the transfer information set in the cell header of the cell transferred to the local area network, and transmits the transfer necessity information to the interconnection device in response to the transfer necessity information request, while
According to the invention of claim 7, the transfer cell management means stores the transfer information from the interconnection device and includes the stored transfer information in the cell header of the cell to be sent out. While transmitting the transfer necessity information indicating the necessity of cell transfer to the interconnection device, the transfer information sent from the interconnection device is stored, the stored transfer information is set in the cell header of the cell to be sent, and the management cell The detection means detects transfer information sent from the interconnection device and outputs it to the transfer cell management means.

Embodiment FIG. 1 shows a LA to which a LAN interconnection device 300 and a station device 110, 210 in an embodiment of the present invention are applied.
An explanatory diagram showing the configuration of the N system, FIG. 2 is a block diagram showing the configuration of the interconnection device 300, and FIG. 3 is the station device 110.
(210) A block diagram showing the configuration of the cell 40, FIG.
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 Figure 1, 100.200 is LAN, 101.2
01 is the transmission line, 110.210 is the transmission line 10, respectively.
1. The station device 300 connected to 201 is the LAN10
This is an interconnection device that connects the LAN 200 and the LAN 200.

In FIG. 2, 301 and 302 are access management means;
303 is a cell relay means, 304 is a transfer information storage means, 3
05.306 is a transfer cell detection means, 307 is a cell header modification means, 308.309 is a transfer necessity information requesting means,
310 and 311 are transfer necessity information detection means, and 312 are transfer necessity information processing means.

In FIG. 3, 111 (211) is an input means such as a keyboard, mouse, data processing device, etc., 112 (212) is a packet generation means, 113 (213) is a cell generation means,
114 (214) is an access management means, 115 (215)
) is a self-directed cell detection means, 116 (216) is a packet restoration means, 117 (217) is a packet decoding means, 11
B (218) is an output means such as a display, printer, data processing device, etc., 119 (219) is a management cell detection means, and 120 (220) is a transfer cell management means.

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

Access management means 30 in the interconnection device 300
1.302 captures empty cells transmitted through transmission paths 101 and 201, respectively, and converts them into cells 40 containing transmitted data, etc.
0, and also receives the cell 400 transmitted from the station equipment 110.210.

For example, as shown in FIG.
Correspondence table 5 that associates the l402(7) value 501.502 and the identification number 503.504 of each station device, etc.
00 is stored. In the example of the correspondence table 500 shown in FIG. 5, the value of the VCl 402 of the cell 400 transmitted between the station device 110 and the station device 210 is
100.200, each is shown to be set to "'Al" A2.

Transfer cell detection means 305 and 306 each have a LAN
VCl 402 of cell 400 received from 100.200
Based on the above correspondence table 500, it is detected whether the cell 400 is a cell to be relayed via the interconnection device 300.

The cell header changing means 307 is configured to change the VCl 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 provides the station device 110, 210 with transfer necessity information indicating whether or not it is necessary to transfer the cell 400 to the other LAN 100, 200. is now required.

The transfer necessity information detection means 310.311 detects transfer necessity information based on a search response cell 620 and a relay request cell 660 from the station device 110.210, which will be described later.

The transfer necessity information processing means 312 creates a correspondence table 500 stored in the transfer information storage means 304 based on the transfer necessity information, and also creates a notification cell 630 to be described later.
, relay request response cell 670, and relay request notification cell 6
80 is generated.

On the other hand, the packet generation means 112 in the station equipment W110 is configured to generate a packet by adding a header to data input from the input means 111 and transmitted to other station equipment 210 or the like.

The cell generating means 113 divides the packet into fixed length data of 48 bytes, for example, and adds a cell header 401 to each divided data as a payload 404 to generate a cell 400.

The access management means 114 captures an empty cell transmitted through the transmission path 101 and transmits the cell 400,
Cell 4 transmitted from the interconnection device 300 and other station devices
00 is received.

The self-destination cell detection means 115 is the access management means 114.
Among the cells 400 received by the station, cell 4 addressed to the local station
00 is selected.

The packet restoration means 116 is adapted to restore 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 it to the output means 118.

The management cell detection means 119 detects the interconnection device 30 among the cells 400 received by the access management means 114.
Search cell 610, notification cell 630, relay request response cell 670, and relay request notification cell 680 transmitted from 0
is selected and output to the transfer cell management means 120.

The transfer cell management means 120 generates a search reply cell 620 or a relay request cell 660 based on the search cell 610 transmitted from the interconnection device 300 or an instruction from the input means 111, and also generates a search response cell 620 or a relay request cell 660 from the interconnection device 300. Transmitted notification cell 630, relay request response cell 670
, or based on the relay request notification cell 680, a correspondence table 500 similar to that of the interconnection device 300 is created and maintained. Also, based on the correspondence table 500, the cell generating means 113 or the self-destination cell detecting means 115 generates a cell to be transmitted via the interconnection device 300, or a cell transmitted to the own station via the interconnection device 300. It instructs to detect the destination cell.

The station device 210 has a similar configuration to the station device 110 described above.

In the above configuration, for example, from the station device 110 to the station device 2
When transmitting data to 10, the station equipment 110.210
, and the interconnection device 300 perform the following operations.

First, the packet generating means 112 of the station device 110 generates a packet based on data input from the input means 111. The cell generating means 113 divides the packet into fixed length data of 48 bytes, and stores each divided data as a payload 404 in a cell header 401.
is added to generate cell 400. Here, in the VCl 402 of the cell header 401, the transfer cell management means 12
Based on the correspondence table 500 stored in 0, a value "A1" indicating that the cell is to be relayed to the LAN 200 via the interconnection device 300 is set.

Furthermore, a value indicating that the cells are generated from the same packet is set in each MID 403. The access management means 114 sends the generated cell 400 to the transmission path 101.

Access management means 301 of interconnection device 300 receives cell 400 sent from station device 110. Transfer cell detection means 305 detects the VC in the received cell 400.
Based on the value “AI” of l402 and the correspondence table 500 stored in the transfer information storage means 304, the cell 40
0 is a cell to be transferred to the station device 210 of the LAN 200.

The cell header changing means 307 is the transfer cell detecting means 305.
Based on the detection results of and the correspondence table 500, VCl40
Change the value of 2 to "'A2". Access management means 30
2 is LA for the cell 400 in which the value of VCl 402 has been changed.
It is sent to the transmission path 201 of N200.

The access management means 214 of the station device 210 receives the cell 400 transferred by the interconnection device 300. The self-directed cell detection means 215 detects the value “A2” of the VCl 402 in the received cell 400 and the transferred cell management means 220.
Based on the correspondence table 500 stored in the cell 40
0 is a cell transferred to the own station via the interconnection device 300, and outputs it to the packet restoration means 216. The self-directed cell detection means 215 also outputs the packet to the packet restoration means 216 when the received cell 400 is a connectionless cell and when it is a connection-oriented cell addressed to the self.

The packet restoration means 216 combines the payloads 404 for each cell 400 with the same MID 403 value 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 it to the output means 118.

Incidentally, the correspondence table 500 stored in the transfer cell management means 120.220 of the station device 110.210 and the transfer information storage means 304 of the interconnection device 300 may be set in advance in each device. Alternatively, the setting may be made based on a request from the interconnection device 300 or the station device 110 or 210 as described below.

First, an example in which the correspondence table 500 is set based on a request from the interconnection device 300 will be described with reference to FIGS. 1 to 6. FIGS. 6(a) to 6(C) respectively show the station device 110.
210 is an explanatory diagram showing 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 communication device 210 and the interconnection device 300. FIG.

In Figures 6(a) to (c), 611.621.63
1 is the cell header, 612.622.632 is the VCI, 6
13.623.633 is the payload, 614.624.
634 is a type field, 615.626.637 is padding to make the cell length a fixed length of, for example, 53 bytes, 625 is a local device identification number field, 635 is a destination device identification number field, and 636 is a notification VCI.
It is a field.

Transfer necessity information requesting means 308 of interconnection device 300.
309, the interconnection device 3
A search cell 610 is generated to search for a station device that needs to perform transmission via 00 and to request transmission of transfer necessity information.

VCl 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 612. Further, a value indicating that the cell is a search cell is set in the payload 6130 type field 614. Access management means 301.
302 connects the generated search cell 810 to the LAN 100.
The management cell detection means 119 of the station device 110 that sends out to the transmission path 10L 201 of 200 detects that the cell received by the access management means 114 is the search cell 61.
If it is detected that the search cell 610 is 0, it outputs the search cell 610 to the transfer cell management means 120.

The transfer cell management means 120 transmits data to the LAN 20 via the interconnection device 300 based on information etc. from the input means 111.
If it is determined that it is necessary to perform transmission with the station device 0, a search response cell 620 is generated as transfer necessity information.

V of the cell header 621 in the search response cell 620
A value indicating that the cell is addressed to the interconnection device 300 is set in the CI 622 . Also, the type field 624 of the payload 623 and the own station! The identification number field 625 is set with a value indicating that it is a search response cell and the station equipment identification number of the station equipment 110, respectively.

Access management means 114 sends this search response cell 620 to transmission path 101.

When the transfer necessity information detection means 310 of the interconnection device 300 detects that the cell received by the access management means 301 is the search response cell 620, it outputs the search response cell 620 to the transfer necessity information processing means 312. do.

The transfer necessity information processing means 312 transmits the LAN to the cell to be transmitted between the station device 110 that sent the search response cell 620 and the station device 110 that sent the search response cell 620 for each destination station device in the LAN 200.
100.200 is determined, and a correspondence table 500 is created. Also, the value of the above VCI is set to the station equipment 11.
A notification cell 630 for notification to 0 is generated.

Cell header 631(7)V in the notification cell 630
A value indicating that the cell is addressed to the station device 110 is set in the CI 632. In addition, the type field 634 of the payload 633 and the partner station device identification number field 63
5 and the notification VCI field 636 are set with a value indicating that it is a notification cell, an identification number of the destination station device, and a VCI value corresponding to the destination station device, respectively. The access management means 301 uses this notification cell 6
30 is sent to the transmission line 101.

The management cell detection means 119 of the station device 110 detects that the cell received by the access management means 114 is the notification cell 63.
If it detects that it is 0, it outputs the notification cell 630 to the transfer cell management means 120. Transfer cell management means 12
0 creates a correspondence table 500 based on the notification cell 630.

Further, when the search cell 610 is sent out from the interconnection device 300, if the station device 210 also needs to perform transmission with the station device of the LAN 100, it similarly sends out a search response cell 620, Transfer cell management means 2 of device 210
20, and transfer information storage means 3 of interconnection device 300
04, a correspondence table 500 is created.

Next, an example in which the correspondence table 500 is set based on a request from the station equipment W110 will be described with reference to FIGS. 1 to 5 and FIG. 7. FIGS. 7(a) to (c) show a relay request cell 660, a relay request response cell 670, and a relay request response cell 670, which are management cells, respectively.
Alternatively, it is an explanatory diagram showing the structure of a relay request notification cell 680.

In Figures 7(a) to (C), 661.671.68
1 is the cell header, 662.672.682 is the VCI, 6
63.673.683 is the payload, 664.674.
684 is the type field, 665 is the destination station equipment identification number, 666.676.687 is padding to make the cell length a fixed length of, for example, 53 bytes, and 675 is the notification V.
The CI field, 685, is a relay request station device identification number field, and 686 is a notification VCI field.

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

V of the cell header 661 in the relay request cell 660
The CI 662 is connected to the interconnection device 300 from the station device 110.
A value indicating that the cell is to be transmitted is set. In addition, the type field 664 and the destination station device identification number field 665 of the payload 663 contain a value indicating that the cell is a relay request cell, and the station device identification number of the destination station device 210 to which transmission is to be made. Set. The access management means 114 sends the generated relay request cell 660 to the transmission path 101.

When the transfer necessity information detection means 310 of the interconnection device 300 detects that the cell received by the access management means 301 is the relay request cell 660, it outputs the relay request cell 660 to the transfer necessity information processing means 312. do.

The transfer necessity information processing means 312 uses the station device W110, which is the relay requesting station device, and the station device 21 indicated by the destination station device identification number field 665 of the relay requesting cell 660.
A VCIO value to be used within the LAN 100.200 for cells transmitted to and from LAN 100.200 is determined, and a correspondence table 500 is created.

It also generates a relay request response cell 670 and a relay request notification cell 680 for notifying the station device 110.210 of the value of ■C■.

Cell header 671 in the relay request response cell 670
The VCI 672 is connected to the station equipment 1 from the interconnection equipment 300.
A value indicating that the cell is to be transmitted is set to 10.

Further, the type field 674 and notification MCI field 675 of the payload 673 contain values indicating that the cell is a relay request response cell, and the station device 110
The VCIO value used for cells transmitted to the station device 210 is set.

On the other hand, the cell header 68 in the relay request notification cell 680
A value indicating that the cell is transmitted from the interconnection device 300 to the station device 210 is set in the VCI 6B2 of 1. Also, payload 6830 type field 684,
The relay request station device identification number field 685 and the notification VCI field 686 contain a value indicating that it is a relay request notification cell, the station device identification number of the station device 1100, and the cell information transmitted from the station device 210 to the station device 110, respectively. The value of VCI used for is set.

Access management means 301 sends these cells to transmission paths 101 and 201, respectively.

When the management cell detection means 119 of the station device 110 detects that the cell received by the access management means 114 is the relay request response cell 670, it outputs the relay request response cell 670 to the transfer cell management means 120. Transfer cell management means 120 creates correspondence table 500 based on relay request response cell 670.

Furthermore, when the management cell detection means 219 of the station device 210 detects that the cell received by the access management means 214 is the relay request notification cell 680, it outputs the relay request notification cell 680 to the transfer cell management means 220. . Transfer cell management means 220 transmits relay request notification cell 680
A correspondence table 500 is created based on.

Note that in the example in which the correspondence table 500 is set based on a request from the interconnection device 300, the station device 110 and the LAN2
In an example in which the correspondence table 500 is set based on a request from the station device 110 while determining the VCIO value to be used for cells transmitted between all the station devices in the station device 1
An example has been described in which only the value of the VCI used for cells transmitted between the station device 210 of the destination specified by the station device 10 is determined. Alternatively, in the latter example, the VCl values for all station devices in the LAN 200 may be determined.

In the former example, the determined VCIO value is transmitted to the station device 11.
In the latter example, the information is transmitted to the station device 210 as well, but this is not limited to either of these examples. That is, if only one-way transmission from the station device 110 is required, the value of VCl is not communicated to the station device 210, but if bidirectional transmission is required, it is communicated to the station device 210 as well. do it.

Further, the number of VCIO values to be transmitted in one management cell is not limited to one, and a plurality of values may be transmitted at once.

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

Furthermore, in this embodiment, a ring-shaped LAN 100
．． Although an example has been described in which 200 are connected by the interconnection device 300, the present invention is not limited to this, and the present invention can be applied to various types of LAN as long as they transmit cells of the same type.

Further, although an example has been described in which two LANs 100.200 are connected by one interconnection device 300, the present invention is not limited to this.
A plurality of LANs may be connected by one interconnection device, or a plurality of LANs may be connected via a plurality of interconnection devices.

Furthermore, the transfer cell detection means 305 of the interconnection device 300 detects the transfer cell, and the cell header change means 307
The modification of the cell header is not limited to the one based on the correspondence table 500 stored in the transfer information storage means 304. For example, the value of VCI can be detected by a decoder, and the cell header can be modified by an encoder, a bit inversion circuit, etc. It's okay.

DETAILED DESCRIPTION OF THE INVENTION According to the invention as set forth in claims 1 and 2, based on the cell header of the cell transmitted in the first local area network, the cell is transmitted via the interconnection device. It detects that the cell is to be transferred to a second local area network, changes the cell header of the cell to a cell header indicating the destination device in the second local area network, and transfers the cell with the changed cell header to the second local area network. By providing cell relay means for transferring cells to a local area network, cells can be relayed without restoring them to packets or regenerating cells.

Therefore, the processing performed by the equipment is reduced, which simplifies the equipment configuration and reduces manufacturing costs.In addition, it is possible to shorten the time required for relaying and easily improve transmission capacity. be effective.

According to the invention of claim 3, there is provided a transfer necessity information requesting means for inquiring the station equipment in each local area network as to whether there is a need for cell transfer to another local area network; , transfer necessity information detection means for detecting transfer necessity information sent from each station device; storing in the transfer information storage means first transfer information set in the cell header of the cell transferred to the local area network, and second transfer information indicating the destination device of the cell in the second local area network; , at least a transfer necessity information processing means for transmitting the first transfer information to the station device that sent the transfer necessity information, so that only the information necessary for cell transfer is automatically set. , the storage capacity required for storing the above information can be kept small, and it is also possible to flexibly respond to changes in the connection structure of the local area network.

According to the invention of claim 4, the transfer necessity information that is spontaneously transmitted from the station equipment in each local area network and which indicates the necessity of cell transfer to another local area network is detected. and storing the first transfer information and the second transfer information in the transfer information storage means based on the transfer necessity information and the transfer necessity information. and transfer necessity information processing means for transmitting the first transfer information to the station, so that only the information necessary for cell transfer is set when cell transfer becomes necessary in each station device. , the storage capacity required to store the above information can be reduced by 4 degrees, and it is also possible to flexibly respond to changes in the necessity of cell transfer in the station equipment.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the 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;
Figure 2 is a block diagram showing the configuration of the interconnection equipment, Figure 3 is a block diagram showing the configuration of the station equipment, Figure 4 is an explanatory diagram showing the structure of the cell, and Figure 5 is the transfer information storage of the interconnection equipment. Explanatory diagrams showing examples of correspondence tables stored in the means and the transfer cell management means of the station device, and FIGS. 6(a) to 6(c) show the structures of search cells, search reply cells, and notification cells, respectively. Explanatory diagrams, FIGS. 7(a) to (c) are explanatory diagrams showing the structures of a relay request cell, a relay request response cell, and a relay request notification cell, respectively, and FIG. 8 is an illustration of the interconnection of a conventional local area network. An explanatory diagram showing the configuration of a local area network system to which the device and the station device are applied,
FIGS. 9 and 10 are explanatory diagrams showing examples of routing tables in the station equipment or interconnection equipment, respectively, and FIG. 11 is an explanatory diagram showing the structures of packets and cells. 100.200...Local area network, 1
10.210... Station device, 111.211... Input means, 112.212... Packet generation means, 113
．． 213...Cell generation means, 114.214...Access management means, 115.215...Self-destination cell detection means, 116.216...Packet restoration means, 117
．． 217...Packet decoding means, 118.218...
- Output means, 119.219... management cell detection means,
120.220...transfer cell management means, 300...
Interconnection device, 301.302... Access management means, 303... Cell relay means, 304... Transfer information storage means, 305.306... Transfer cell detection means, 30
7...Cell header changing means, 308.309...Transfer necessity information requesting means, 310.311...Transfer necessity information detection means, 312...Transfer necessity information processing means

Claims (7)

[Claims] (1) A local area network interconnection device that relays cells between at least two local area networks that perform packet communication using fixed-length cells in which packets are divided into fixed-length data and cell headers are added. detecting that the cell is a cell to be transferred to the second local area network via the interconnection device based on the cell header of the cell transmitted in the first local area network; A local area network comprising 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 device. (2) The cell relay means includes first transfer information set in a cell header of a cell transmitted in the first local area network and transferred to the second local area network, and a second local area network. transfer information storage means for storing second transfer information indicating a destination device of the cell in correspondence with each other; a cell header of a cell transmitted in the first local area network; and a second transfer information stored in the transfer information storage means Transfer cell detection means for detecting that the cell is a cell to be transferred to a second local area network via an interconnection device based on transfer information of a second local area network stored in a transfer information storage means; 2. A local area network interconnection device according to claim 1, further comprising cell header changing means for changing said cell header based on transfer information of said cell header. (3) In the local area network interconnection device according to claim 2, the transfer necessity inquires of the station device in each local area network whether there is a need for cell transfer to another local area network. information requesting means; transfer necessity information detection means for detecting transfer necessity information sent from each station device in response to the request; Transfer necessity information processing means for storing the first transfer information and the second transfer information in a transfer information storage means, and transmitting the first transfer information to at least the station device that has transmitted the transfer necessity information. A local area network interconnection device characterized by: (4) The local area network interconnection device according to claim 2, wherein the necessity for cell transfer to another local area network, which is spontaneously transmitted from the station equipment in each local area network, is provided. a transfer necessity information detection means for detecting transfer necessity information indicating the transfer necessity information; and based on the transfer necessity information, the first transfer information;
and a 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 device that has transmitted the transfer necessity information. local area network interconnection equipment. (5) In local area network station equipment that performs packet communication using fixed-length cells, in which a packet is divided into fixed-length data and a cell header is added, the cell header of the transmitted cell is 1. A station device for a local area network, comprising a transfer cell management means for setting transfer information indicating that the cell is a cell transferred to the local area network. (6) In local area network station equipment that performs packet communication using fixed-length cells, in which packets are divided into fixed-length data and cell headers are added, data is sent from interconnection equipment to other local area networks. management cell detection means for detecting a transfer necessity information request that inquires whether there is a need for cell transfer of a cell, and transfer information to be set in a cell header of a cell to be transferred to another local area network; a transfer cell management means for transmitting transfer necessity information to an interconnection device according to the above, while storing transfer information from the interconnection device and setting the stored transfer information in a cell header of a cell to be transmitted; A local area network station device comprising: (7) In a local area network station device that performs packet communication using fixed-length cells in which packets are divided into fixed-length data and cell headers are added, it indicates the necessity of cell transfer to another local area network. A transfer cell management means for transmitting transfer necessity information to the interconnection device, storing the transfer information sent from the interconnection device, and setting the stored transfer information in the cell header of the cell to be sent; A station device for a local area network, comprising: management cell detection means for detecting transfer information to be transferred and outputting it to the transfer cell management means.