JPH05199241A - Device for connecting mutually between lan - Google Patents

Abstract

PURPOSE:To improve throughput by preventing repeating performance from being limited by internal data transfer even when a lot of LANs are connected. CONSTITUTION:A cell switch 8 is provided with plural input ports and output ports and when a cell composed of a header part and an information part having a fixed length is inputted to an optional input port, the cell is outputted to the output port corresponding to a destination number described at the header part of the cell. Cell division parts 19, 20 and 21 divide a packet into units of the cell, store destination numbers decided by repeat selection parts 25, 26 and 27 to the header parts of respective cells and supply those cells to the input ports of the cell switch 8. Packet restoring parts 22, 23 and 24 restore the packet by assembling the cells from the output ports of the cell switch 8 according to order described at the header parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a local area network (hereinafter referred to as "LAN") in a data communication system.
(Hereinafter referred to as)) for interconnecting LANs.

[0002]

2. Description of the Related Art A conventional LAN interconnection device, for example, is shown in FIG. 4 ("Data Communications International" Septembe).
r, 1991 vol. 20 No. 11 137-1
(See page 38). This conventional LAN interconnection device includes a large number of LAN connecting parts including LAN connecting parts 43 and 44, and a large number of LAN connecting parts including LAN connecting parts 43 and 44, respectively. And a bus 45 connecting the parts. The LAN connection units 43 and 44 include LAN control units 46 and 47, relay units 48 and 49, buffer units 50 and 51, and a transfer control unit 5.
2, 53 are provided. The other LAN connection units have the same configuration. The LAN control units 46 and 47 include LANs 41 and 4
The transmission / reception control to 2 is performed. The relay units 48 and 49 control the relay of received packets. Buffer unit 50, 51
Temporarily stores the packet for relaying the packet with another LAN connection unit. Transfer control units 52, 53
Controls data transfer to and from another LAN connection.

In this conventional LAN-to-LAN interconnection device, when the LAN control unit 46 receives a packet from the LAN 41, the relay unit 48 retrieves the destination address set in the received packet from the internally provided retrieval table. To do. The station address of the terminal and the number of the LAN connection unit to which the terminal is connected are registered in this search table. As a result of searching the destination address from the search table, if the LAN connection unit to be connected is the LAN connection unit 44, the packet is temporarily stored in the buffer unit 50, and then the transfer control unit 52 connects to the LAN via the bus 45. It is transferred to the buffer unit 51 of the unit 44. At this time, the transfer control unit 52 performs the arbitration work and then performs the actual data transfer in order to use the bus 45 after confirming that the bus 45 is not used by the transfer control unit of another LAN connection unit. .. After that, the relay unit 48 notifies the relay unit 49 of the LAN connection unit 44 via the bus 45 that the packet has been transferred to the buffer unit 51. After receiving the notification, the relay unit 49 transfers the packet to the LAN control unit 47. The LAN control unit 47 transmits the packet to the LAN 42. The packet is relayed by the above operation.

[0004]

In the conventional LAN interconnection device described above, since a relayed packet is exchanged between LAN connection units via the bus 45, a large number of LANs are connected.
In the case of the LAN-to-LAN interconnection device connected to, the same bus 45 is shared by a number of LAN connection units, and there is a problem that the relay performance is limited by the bus transfer speed.

The present invention has been made in view of the above circumstances, and even when a large number of LANs are connected, internal data transfer does not limit the relay performance and the processing performance can be improved between LANs. An object is to provide a connection device.

[0006]

The present invention has a plurality of input ports and output ports, and when a cell constituted by a fixed length header section and information section is input to an arbitrary input port, A cell switch that outputs a cell to the output port corresponding to the destination number described in the header section,
The LAN control unit that controls access to the LAN and this L
A relay selection unit that determines the destination number of the header of the cell by referring to the destination address of the packet received by the AN control unit, and the information of each cell by dividing the packet received by the LAN control unit into cell units A cell division unit that stores a divided part of the packet contents in the unit, stores the destination number determined by the relay selection unit in the header of each cell, and supplies the destination number to the input port of the cell switch; A packet restoration unit that restores a packet by assembling cells from the output port of the cell switch according to the order described in the header portion, and a packet received by the LAN control unit, relayed to the cell division unit, and the packet A LAN provided with a relay unit that relays the packet from the restoration unit to the LAN control unit, and is prepared for each connected LAN.
An interface unit is provided, and the packet received from the LAN is divided into cells by the LAN interface unit and passed to the cell switch. The cell switch distributes the cells to the LAN interface unit corresponding to the destination LAN.
The interface unit restores cells to packets and LA
It is characterized in that it is configured to supply to N.

[0007]

The cell switch has a plurality of input ports and output ports, and when a cell composed of a fixed length header section and information section is input to an arbitrary input port,
The cell is output to the output port corresponding to the destination number described in the header of the cell. The LAN control unit controls access to the LAN. The relay selection unit refers to the destination address of the packet received by the LAN control unit and determines the destination number of the header portion of the cell. The cell division unit divides the packet received by the LAN control unit into cells, stores the divided part of the contents of the packet in the information section of each cell, and the relay selection section in the header section of each cell. It stores the destination number determined in step 3 and supplies it to the input port of the cell switch. The packet restoration unit restores a packet by assembling the cells from the output port of the cell switch in the order described in the header portion thereof. The relay unit is LA
The packet received by the N control unit is relayed to the cell division unit, and the packet from the packet restoration unit is relayed to the LAN control unit.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a LAN system adopting a LAN interconnection device according to an embodiment of the present invention. This LAN system includes a LAN interconnection device 1 and a LAN.
LANs 2, 3 and 4 connected to the inter-connection device 1, and L
It is provided with terminals 5, 6, 7 and the like connected to ANs 2, 3, 4. The LAN interconnection device 1 includes a cell switch 8
And LAN interface units 9, 10, and 11, and the LAN interface units 9, 10, and 11 are LA
It is connected to N2,3,4. The station addresses of the terminals 5, 6 and 7 are A, B and C.

FIG. 2 is a block diagram of the LAN interconnection device 1. LAN interface parts 9, 10, 11 of the LAN interconnection device 1 are LAN control parts 13, 14, 15,
Relay units 16, 17, 18 and cell division units 19, 20, 2
1, packet restoration units 22, 23, 24, and relay selection units 25, 26, 27. The cell switch 8 is
The cells transferred from the LAN interface units 9, 10 and 11 via the cell division units 19, 20 and 21 are transferred to the LAN interface unit of the destination by determining the destination according to the destination number stored in the header of the cell. .. The input ports of the cell switch 8 are LAN interface units 9, 10,
11 are connected to the cell division units 19, 20, and 21,
The output port of the cell switch 8 is connected to the packet restoration units 22, 23, 24 of the LAN interface units 9, 10, 11. That is, the cell switch 8 refers to the destination number set in the header part of the cell and outputs the cell input from an arbitrary input port to the output port designated by the destination number. The technical report SSE90-36 of the Institute of Communication Engineers and the like have already disclosed a practical cell switch with 8 inputs and 8 outputs. A feature of the cell switch 8 is that when the destination output ports are not the same, cells can be exchanged among the LAN interface units 9, 10, 11 independently during the same time. For example, from the LAN interface unit 11 to the LAN
While the plurality of divided cells are being transferred to the interface unit 12, the LAN interface unit 12
It is possible to transfer cells generated by dividing different packets to the LAN interface unit 13. L
The AN control units 13, 14, 15 are connected to the LAN 2,
Controls packet transmission / reception to 3 and 4. Relay section 16, 1
Reference numerals 7 and 18 relay the packets sent from the LAN control units 13, 14 and 15 to the cell division units 19, 20 and 21, and LAN control the packets sent from the packet restoration units 22, 23 and 24. It is relayed to the parts 13, 14 and 15. The cell division units 19, 20, 21 are connected to the relay units 16, 1
The packets sent from the routers 7 and 18 are divided in order to be stored in the information part of the cell composed of the fixed length header part and the information part, and the destination LAN selected by the relay selecting parts 25, 26 and 27. A destination number designating the interface section is set in the header section and transferred to the cell switch 8. The packet restoration units 22, 23, 24 restore the packet from the information of the header portion of the cell transferred from the cell switch 8.
The relay selecting units 25, 26, 27 include the relay units 16, 17, 1
It is determined whether or not the packet sent to No. 8 needs to be relayed, and if relayed, to which LAN interface unit it is to be transmitted.

FIG. 3 is an explanatory diagram of a format of a cell switched by the cell switch 8. The cell is composed of a fixed length header section 29 and a fixed length information section 30. The header part 29 includes a destination field 31, a type field 32, a sequence number field 33,
Message identification field 34 and size field 3
5 and 5. In the destination field 31,
The destination number for selecting the output port of the cell switch 8 is stored. The type field 32 stores information indicating that the cell is a first cell, an intermediate cell, or a last cell when the packet is divided into cells. A continuous value is set in the sequence number field 33 in order to confirm that there is no omission in the received cell. Message identification field 34
In order to indicate that a series of cells constitutes the same packet, the same value is set to a plurality of cells constituting the same packet. Size field 3
Information indicating the size of valid data stored in the information unit 30 in the final cell is stored in field 5, and it is an invalid field other than the final cell.

Next, the operation will be described. When a packet addressed to the terminal 6 is transmitted from the terminal 5, the LAN interconnection device 1
The LAN control unit 13 of the LAN interface unit 9 of
The packet is received from the AN 2 and transferred to the relay unit 16. As a result, the relay unit 16 queries the relay selection unit 25 for the destination address B. The relay selection unit 25 includes the terminal addresses and LANs connected to the terminals 5, 6, and 7.
The numbers of the interface units 9, 10, 11 are registered in advance, and when the destination address B is inquired, the relay unit 16 informs the terminal 6 that the terminal 6 is connected to the LAN 3.
This is notified by returning the destination number of the LAN interface unit 10. As a result, the relay unit 16 notifies the cell division unit 19 of the packet contents and the destination number of the LAN interface unit 10 of the destination. As a result, the cell division unit 19 performs the following processing. That is, the notified packet is divided into equal sizes, and the divided contents are stored in the information section 3 of the cell.
0, and the LA is stored in the destination field 31 of the header section 29.
The destination number of the N interface unit 10 is set, the flag indicating the beginning is set in the type field 32 of the cell located at the beginning of the packet, and the type field 32 of the cell located in the middle is indicated that it is intermediate. A flag is set, and a flag indicating the end is set in the type field 32 of the cell located at the end. If the information portion 30 of the cell located at the end is not completely filled, 0 is inserted as padding in the remaining portion of the information portion 30, and a valid data size is set in the size field 35. Also, a series of consecutive sequence numbers from the first cell to the last cell is set in the sequence number field 33, and the same value is set in the message identification field 34 for these cells that are the same packet. A series of cells thus generated from one packet is supplied to the input port of the cell switch 8. As a result, the cell switch 8 refers to the destination field 31 of the header portion 29 of each cell, and is addressed to the LAN interface portion 10.
A series of cells are output to the output port connected to the interface unit 10. As a result, the packet restoration unit 23 of the LAN interface unit 10 receives the cells sent from the cell switch 8, and sets the same value in the message identification field 34 starting from the cell having the type value indicating the beginning. FIFO in sequence number order
(Not shown) to restore the packet. Since the last cell may have padding stored in the information section 30, only the size indicated by the size field 35 is valid. The packet restored in this way is passed to the LAN control unit 14, sent to the LAN 3, and the terminal 6 sends the LA data.
The packet sent to N3 is taken into its own station. In this way, the communication from the terminal 5 to the terminal 6 is performed.

In this way, the LAN interface unit 9,
Since the cell switch 8 is used for the relay between 10 and 11, the transfer processing by an arbitrary combination can be independently performed, and when the relay processing is performed, the transfer speed does not become the limitation of the processing speed. Therefore, the processing performance can be improved.

[0013]

As described above, according to the present invention, when a cell having a plurality of input ports and output ports and having a fixed length header section and information section is input to an arbitrary input port. , The cell switch that outputs the cell to the output port corresponding to the destination number described in the header of the cell, the LAN control unit that controls access to the LAN, and the destination address of the packet received by this LAN control unit. The relay selection unit that refers to the destination number of the header of the cell and the packet received by the LAN control unit is divided into cells, and the divided part of the packet contents is stored in the information section of each cell. The cell division unit that stores the destination number determined by the relay selection unit in the header of each cell and supplies it to the input port of the cell switch, and the cell from the output port of the cell switch A packet restoration unit that restores packets by assembling in the order described in the header section, and a packet received by the LAN control unit to the cell division unit and a packet from the packet restoration unit to the LAN control unit. It has a relay unit and a LAN interface unit prepared for each connected LAN. Packets received from the LAN are divided into cells by the LAN interface unit and passed to the cell switch, and the cell switch supports the destination LAN. The cells are distributed to the LAN interface unit that is used, and the cells are restored to packets by the LAN interface unit and supplied to the LAN. Since a cell switch is used for relaying between the LAN interface units, any combination is possible. If you can perform the transfer process independently and perform the relay process, Without the transfer speed becomes a processing speed limitations in superior effect of being able to improve the processing performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a LAN system adopting a LAN interconnection device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a LAN interconnection device according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a cell format.

FIG. 4 is a configuration diagram of a conventional LAN interconnection device.

[Explanation of symbols]

 1 LAN interconnection device 2 LAN 3 LAN 4 LAN 8 cell switch 9 LAN interface unit 10 LAN interface unit 11 LAN interface unit 13 LAN control unit 14 LAN control unit 15 LAN control unit 16 relay unit 17 relay unit 18 relay unit 19 cell Dividing unit 20 Cell dividing unit 21 Cell dividing unit 22 Packet restoring unit 23 Packet restoring unit 24 Packet restoring unit 25 Relay selecting unit 26 Relay selecting unit 27 Relay selecting unit 29 Header unit 30 Information unit

Claims (1)

[Claims] 1. A destination number described in a header part of a cell when a cell having a plurality of input ports and output ports and having a fixed length header part and an information part is input to an arbitrary input port. A cell switch that outputs cells to the output port corresponding to the LAN, a LAN control unit that controls access to the LAN, and the L switch.
A relay selection unit that determines the destination number of the header of the cell by referring to the destination address of the packet received by the AN control unit, and the information of each cell by dividing the packet received by the LAN control unit into cell units A cell division unit that stores a divided part of the packet contents in the unit, stores the destination number determined by the relay selection unit in the header of each cell, and supplies the destination number to the input port of the cell switch; A packet restoration unit that restores a packet by assembling cells from the output port of the cell switch according to the order described in the header portion, and a packet received by the LAN control unit, relayed to the cell division unit, and the packet A LAN provided with a relay unit that relays the packet from the restoration unit to the LAN control unit, and is prepared for each connected LAN.
An interface unit is provided, and the packet received from the LAN is divided into cells by the LAN interface unit and passed to the cell switch. The cell switch distributes the cells to the LAN interface unit corresponding to the destination LAN.
The interface unit restores cells to packets and LA
An inter-LAN interconnection device characterized by being configured to supply to N.