JP2849259B2 - LAN connection method by ATM network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for connecting LANs by an ATM exchange constituting an ATM network in order to perform communication between terminal devices connected to different LANs.

[0002]

2. Description of the Related Art FIG. 8 shows an ATM (Asynchronous Transfer) which divides data into fixed-length data units called cells and transfers data in the cell units.
r Mode; Asynchronous Transfer Mode)
FIG. 2 is a system configuration diagram when a connection between N lines (Local Area Network) 5 is performed. In FIG. 8, 1a to 1c respectively connect the LAN line 5 to TA (Ter).
AT accommodated via the Minor Adapter 3
M exchanges A to C, 2 for ATM line, 3a to 3c for LAN
TAa to c for connecting the line 5 to the ATM exchange 1;
The AN lines 6a to 6c are terminal devices connected to the LAN line 5 via the transmission device 4. In the following description, one of the terminal devices 6a to 6c is referred to as a terminal device 6.

[0005] FIG. 9 shows M
This shows the configuration of an AC (Media Access Control) frame 7, and the MAC frame 7 has a destination address (DA [Destination Address).
ss]) 71, the source address (SA [Source
Address]) 72 and an information section 73. FIG. 10 shows a configuration of a cell 8 transmitted to the ATM line 2, and the cell 8 is a VCI (Virtual CV).
It comprises a header section 81 including a channel identifier (logical channel identifier) 811 and an information section 82.

Next, the operation of the conventional LAN connection method will be described. First, the MAC transmitted by the terminal device 6
The frame 7 is transmitted to the LAN line 5 via the transmission device 4. TA3 receives the MAC frame 7 from the LAN line 5, and checks the DA 71 of the received MAC frame 7. If the DA 71 indicates the address of the terminal device 6 in the LAN accommodated in the ATM exchange 1, the received MA
The C frame 7 is discarded. DA71 is its own ATM switch 1
If the address of the terminal device 6 in the LAN accommodated in the terminal 3 is not indicated, it is checked which TA3 is connected to the LAN to which the terminal device 6 having that address is connected, and the received MAC frame 7 is transmitted to the TA3. To determine.

Next, TA3 originates a call to the local ATM exchange 1, and upon receiving the call, the local ATM exchange 1 transmits the TA3 to be transmitted.
Is called to the other ATM exchange 1 to which is connected. And
The two ATM exchanges 1 set a route so that the cell 8 is transmitted to the ATM exchange 1 on the receiving side. In addition, the TA3 acquires the VCI 811 and divides the MAC frame 7 into one or more cells 8 of a fixed length as shown in FIG. 11, and divides the cell 8 into its own ATM exchange 1 and the other ATM exchange 1
To the other party's TA3 via TA3 on the receiving side
From the sequentially received cells 8 as shown in FIG.
The frame 7 is assembled and transmitted to the LAN line 5.

[0006] The MAC frame 7 is received by the terminal device 6 indicated by the DA 71 through the transmission device 4. One M
When transmission of all the cells 8 of the AC frame 7 is completed, the TA 3 on the transmitting side disconnects the call and the ATM switch 1 on the transmitting side releases the path.

[0007] Regarding a conventional connection method between LANs using an ATM switch, the Institute of Electronics, Information and Communication Engineers technical report SS
E89-40 "Study of ATM and MAN adaptation function for LAN connection" (The Institute of Electronics, Information and Communication Engineers 1
(Issued July 19, 989).

[0008]

Since the conventional LAN-to-LAN connection system using the ATM network is configured as described above,
The ATM switch 1 needs to perform a call control process for each MAC frame 7 to set and release the transmission path of the cell 8, and the processing load increases and the transmission waiting time of the MAC frame 7 required for the call control process increases. Further, the transmitting side TA3 needs to have information for determining the receiving side TA3 connected to the LAN line 5 to which the destination terminal device 6 is connected, and accordingly, the terminal device 6 to be connected to the LAN line 5 is required. If the number is large, there is a problem that a large amount of information must be provided.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and there is no need to perform a call control process at the time of transferring the MAC frame 7, so that the transfer waiting time of the MAC frame 7 can be reduced and the TA3 , An AT that eliminates the need to set information for associating the destination terminal device 6 with the TA3 connected to the LAN line 5 to which the terminal device 6 is connected
An object of the present invention is to obtain an inter-LAN connection method using an M network.

[0010]

According to the present invention, A
The LAN-to-LAN connection method using a TM network is a broadcast-type logical connection that broadcasts a LAN frame signal decomposed into cells from one terminal adapter to all other terminal adapters, and a one-to-one connection between terminal adapters. A first address table holding addresses of all terminal devices connected to the LAN accommodated therein, and a terminal device accommodated by another terminal adapter are set. And a second address table holding a logical channel identifier for identifying a logical connection connecting the present terminal adapter and the other terminal adapter. When the terminal adapter receives a frame from the terminal, the terminal adapter Addresses and retained in each table A routine for collating the address of the terminal device which has been received and performing predetermined processing based on the result of the collation, and a routine for collating the type of cell or the destination address in the cell with the terminal device address in the holding table when receiving the cell from the ATM network. And a routine for performing the above processing.

According to a second aspect of the present invention, there is provided an inter-LAN connection system using an ATM network, wherein a LAN frame signal decomposed into cells is broadcast from one terminal adapter to all other terminal adapters between terminal adapters. One-to-one connection between logical connection and each terminal adapter
And a point-to-point logical connection to be connected to each terminal adapter.
A first address table holding addresses of all terminal devices connected to the terminal adapter, an address of a terminal device accommodated by another terminal adapter, and a logical channel identifier for identifying a logical connection connecting the present terminal adapter and the other terminal adapter The terminal adapter has a second address table that holds the destination terminal device in the frame when receiving the frame from the terminal and compares the destination address in the table with the address of the terminal device held in each table, and accommodates the destination terminal device according to the result of the comparison. If it is not possible to identify which terminal adapter is used, the query cell is transmitted to all other terminal adapters, and each divided data cell until a response cell is received from the other terminal adapter is also transmitted by the broadcast logical connection. is there.

According to a third aspect of the present invention, there is provided an inter-LAN connection system using an ATM network in which a LAN frame signal divided into cells between terminal adapters is broadcast from one terminal adapter to all other terminal adapters. A type logical connection and a point-to-point logical connection for connecting each terminal adapter on a one-to-one basis are set.
A first address table holding the addresses of all the terminal devices connected to N, an address of the terminal device accommodated by another terminal adapter, and a logical channel for identifying a logical connection connecting the present terminal adapter and the other terminal adapter The terminal adapter has a second address table provided with an area for holding an identifier and a timer value. When receiving a frame from the terminal, the terminal adapter compares the destination address in the frame with the address of the terminal device held in each table. A routine for performing predetermined processing based on a result of the verification, a routine for performing predetermined processing based on a result of verification of a cell type or a destination address in the cell and a terminal device address in a holding table when a cell is received from the ATM network,
A routine is provided for deleting a terminal device that has not communicated for a time exceeding the timer value from the table.

[0013]

According to the first aspect of the present invention, when the terminal adapter transmits a data cell created by dividing a frame, if the terminal adapter accommodating the destination terminal device can be specified by the destination address, the terminal adapter is transmitted to the terminal adapter. The data cell is transmitted by a point-to-point logical connection. If the data cell cannot be specified, the inquiry cell is broadcast to all other terminal adapters, and the route is determined by a simple exchange of the inquiry cell and the response cell. Also, AT
The terminal adapter receiving the cell from the M network checks the type of the cell, and if the cell is an inquiry cell, updates the second address table as necessary if the address is present in the own LAN and returns a response cell to the ATM. Otherwise, discard the interrogation cell. If the cell is a response cell, the second address table is updated as necessary, and the data cell is returned to the ATM network. If the cell is a data cell, it is assembled into a frame and transmitted within its own LAN.

According to the second aspect of the present invention, when the terminal adapter transmits a data cell created by dividing the MAC frame, the terminal adapter accommodating the destination terminal device can be specified similarly to the first aspect of the present invention. In that case, the data cell is transmitted to the terminal adapter by a point-to-point logical connection. If the data cell cannot be specified, the inquiry cell is broadcast to all other terminal adapters, and then the data cell is broadcast. Further, the terminal adapter which has received the cell from the ATM, according to the type of the cell and by collating with the address table, as in the first aspect of the invention,
Return or discard the response cell, or return the data cell.
If the cell is a data cell, the received data cell is assembled into a frame and then transmitted to the terminal device within the LAN.

According to the third aspect of the present invention, each terminal adapter has a first address table and a second address table, as in the first and second aspects of the present invention. An area for holding a timer value is provided, and among terminal addresses registered in the second address table, for a terminal device that has not communicated for a certain period of time, a second address provided in a corresponding terminal adapter is provided. The address and the logical connection identification in the table are deleted.

[0016]

[Embodiment 1] Hereinafter, an embodiment of the first invention will be described with reference to the drawings. In this embodiment. In the system configuration diagram shown in FIG. 8, a broadcast-type logical connection (broadcast-type VC [Virtua1 Connect) for broadcasting cells 8 transmitted from one TA3 to all other TA3s is provided between each TA3.
[point] and a point-to-point logical connection (individual VC) for connecting the TA3 on a one-to-one basis. Here, TAa3a, TAb3b and TAc
3c have VCs of “1”, “2” and “3”, respectively.
It is assumed that I811 is associated.

When the cell 8 is broadcast from the TAa 3a in the broadcast type VC, the TAa 3a transmits the VCI 811 of the cell 8 to its own T
A1 is set to “1” corresponding to A3 and transmitted, and TAb3b,
TAc3c receives cell 8 of VCI 811 "1".
When transmitting the cell 8 from the TAa 3a to the TAc 3c by the individual VC, the TAa 3a sets the VCI 811 of the cell 8 to "3" and transmits the cell 8, and the TAc 3c receives the cell 8 of the VCI 811 "3".

As described above, when transmitting by the broadcast type VC,
The transmitting side TA3 receives the cell 8 having the VCI 811 set with the value associated with the TA3, and the receiving side TA3
Is the VCI set by the value associated with the transmitting side TA3.
Cell 8 having 811 is received.

In the case of transmission by an individual VC, the transmitting side TA3 has a VCI having a value associated with the receiving side TA3.
The cell 8 in which the cell 811 is set is transmitted, and the receiving side TA3 transmits the VCI 811 set to the value associated with the transmitting side TA3.
Receiving the cell 8 having It is assumed that such a VC is set.

FIG. 1 is a configuration diagram of a local address filtering table (L-AFT) 9 and a remote address filtering table (R-AFT) 10 provided in the TA 3. The L-AFT 9 is a table that always holds the addresses of all the terminal devices 6 accommodated in the own TA 3,
The R-AFT 10 is a table for holding the address of the terminal device 6 accommodated by the other TA 3 and the VCI 811 indicating the VC of the TA 3 as a pair by learning.
01 and a VCI area 102.

FIG. 2 shows an inquiry cell (INQ [INQu
ire] cell) 8a, response cell (ANS [ANSwe]
[r] cell) 8b and a detailed format diagram of a data cell (DATA cell) 8c created by dividing the MAC frame 7. FIG. These cells have the same configuration as that of FIG. 10, but the header section 81 has an MID (Multiplexin).
g IDentifier) 812.

The INQ cell 8a includes the VCI 811 and the MID
It comprises a header section 81 including 812, an information section 82 including DA821 and SA822. ANS cell 8b has V
Header section 81 including CI 811 and MID 812 and DA8
21 including an information section 82. The DATA cell 8c includes a header section 81 including the VCI 811 and the MID 812.
And an information section 82 including the divided MAC frame 7.

Here, the INQ cell 8a and the ANS cell 8b
And the identification of the DATA cell 8c is the MID of the header 81.
812, and thereafter, the INQ cell 8a, ANS
The MID 812 of the cell 8b is set to "0" and "1", respectively, and the MID 812 of the DATA cell 8c is set to "0" and "1".
Assume other than

FIG. 3 shows that TA3 is connected from L-LAN line 5 to MA.
9 is a flowchart illustrating an operation when a C frame 7 is received. The operation will be described below with reference to the drawings. L-AFT 9 is searched in DA 71 of MAC frame 7 and DA 7 is searched.
1 exists in the L-AFT 9, the destination terminal device 6
The MAC frame 7 is discarded because A3 is accommodated. If not present, the destination terminal device 6 is assumed to be accommodated by another TA3, and therefore the MAC frame 7 is stored in the cell 8
Divided into At this time, the DA 71 searches the terminal address area 101 of the R-AFT 10 and the DA 71
If it exists in the terminal address area 101 of T10, the value of the corresponding VCI area 102 is
11, and transmits the DATA cell 8c to the TA3 accommodating the destination terminal device 6 by the individual VC. If not,
The INQ cell 8a is broadcast to all other TA3s by broadcast VC.

FIG. 4 is a flowchart showing the operation when the TA3 receives the cell 8 from the ATM network. Hereinafter, the operation will be described with reference to the drawings.

First, the case where the received cell 8 is the INQ cell 8a will be described. DA of received INQ cell 8a
821 is searched for L-AFT9 and the DA821 is LA
If the destination terminal device 6 does not exist in the FT 9, the destination terminal device 6 discards the MAC frame 7 because another TA 3 accommodates the destination terminal device 6. If the DA 812 exists in the L-AFT 9, it means that the own TA 3 accommodates the destination terminal device 6, so that the R-AFT 10 is searched in SA822 and the SA 822 is searched.
Is not present in the R-AFT 10, the SA-822 and the VCI 811 of the INQ cell 8a are respectively stored in the R-AFT 10.
Terminal address area 101 of T10 and VCI area 10
Register in 2 (learn). Then, the VCI 811
Is set in the ANS cell 8b and transmitted to the ATM network by the individual VC.

Next, a case where the received cell 8 is the ANS cell 8b will be described. DA of received ANS cell 8b
821 and the VCI 811 of the ANS cell 8b are registered (learned) in the terminal address area 101 and the VCI area 102 of the R-AFT 10, respectively. And the VC
I811 is set in DATA cell 8c, and AT
Send to M network.

Finally, the received cell 8 is a DATA cell 8
The case of c will be described. Received DATA cell 8c
Into the MAC frame 7 and the L connecting the own TA3
Send to AN.

FIG. 5 shows the exchange of cells 8 when the MAC frame 7 is transmitted from the terminal device 6 accommodating the TAa 3a to the TAa 3a, and the L-AFT 9 and the R-AF in each TA 3.
It is explanatory drawing which shows a mode of T10. According to this illustration,
The cell transfer operation will be described. Terminal device 6a shown in FIG.
Transmits a MAC frame 7 addressed to the terminal device 6c. Also, the L-AFT 9 of each TA3 has its T
It is assumed that addresses of all terminal devices 6 accommodated in A3 are registered, no information is registered in R-AFT 10, and each MAC frame 7 is divided into two cells 8. I do.

LA accommodated in ATM exchange A1a
Assuming that the terminal device 6a connected to the N line has transmitted the MAC frame 7, first, the TAa 3a
Frame 7 is received. TAa3a is the MAC frame 7
The contents "c" of the DA 71 are checked. Here, “c” of the DA 71 indicates the terminal device 6c. DA71
Since “c” is not registered in either the L-AFT 9a or the R-AFT 10a, the INQ cell 8a is created.
The VCI 811 of the INQ cell 8a is "1" which is the VCI 811 corresponding to TAa, and the MID 812 is INQ
"0" indicating that the cell is a cell 8a;
The content “c” of the DA 71 of the C frame 7 and the content “a” of the SA 72 of the MAC frame 7 are set in SA822.

TAa3a is the INQ set as described above.
The cell 8a is transmitted to the ATM exchange A1a by broadcast VC,
This ATM exchange A1a and other ATM exchanges B and C
Broadcast to all other TA3s by (1b, 1c).

TAb, c (3b, 3c) are respectively L-AFT (9) in DA821 of received INQ cell 8a.
b, 9c), and if registered, the ANS cell 8b
Create At this time, the SA 822 of the INQ cell 8a becomes R
If not registered in the AFT 10, the SA 822 and the corresponding VCI 811 are registered. DA821
Since "c" indicates the terminal device 6c, only the TAc 3c creates the ANS cell 8b. VC of ANS cell 8b
I811 has the same value "1" as the VCI 811 of the received INQ cell 8a, MID812 has the value "1" indicating that it is the ANS cell 8b, and DA821 has the same value "c" as the DA821 of the received INQ cell 8a. Set.

Further, SA822 of the INQ cell 8a is R-
Since it is not registered in the AFT 10c, its SA822
Is registered in the terminal address area 101c, and the corresponding VCI 811 "1" is registered in the VCI area 102c. Then, the ANS cell 8b is set to TAa3a by the individual VC.
Return to. Since the ANS cell 8b is transmitted by the individual VC, the VCI 81 of the transmission source is transmitted by the ATM switch C1c on the transmission side.
1 is converted to "3" and TAa3a is provided with VCI 811 "3".
Arriving at.

The TAa 3a receives the ANS cell 8b, divides the MAC frame 7 into two, and
Create The VCI 811 of the DATA cell 8c has the same value “3” as the VCI 811 of the received ANS cell 8b,
In the MID 812, a value “2” other than “0” and “1” indicating the data cell 8c is set. The DA “c” 821 of the ANS cell 8b is the R-AFT 10a
Is not registered in the VCI 811 corresponding to the DA 821 in the terminal address area 101a.
“3” is registered in the VCI area 102a. And 2
One DATA cell 8c is transmitted to TAc3c by individual VC. Since these DATA cells 8c are transmitted by individual VCs, the source ATM switch A1a transmits the VCIs 8c of the transmission source.
11 is converted to "1", and VCI 811 is stored in TAc3c.
Reach with "1".

The TAc 3c assembles the received DATA cell 8c as shown in FIG.
Send to LAN.

Embodiment 2 FIG. Hereinafter, one embodiment of the second aspect of the present invention will be described. In this embodiment, as described in claim 1, in the system configuration diagram shown in FIG.
A broadcast type VC and an individual VC are set in advance between A3 and each TA3
The L-AFT 9 and the R-AFT 10 shown in FIG. 1 are provided, and the INQ cell 8a, the ANS cell 8b and the DATA cell 8c shown in FIG. 2 are exchanged.
The following operation is performed.

FIG. 6 shows the terminal device 6 accommodated by the TAa 3a.
From the cell 8 when the MAC frame 7 is transmitted from the to the TAa 3a and the l-AFT 9 in each TA 3
FIG. 4 is an explanatory diagram showing a state of data search in R-AFT 10.

The operation will be described based on the above description.
Similar to the first aspect, the case where the terminal device 6a shown in FIG. 8 transmits the MAC frame 7 for the terminal device 6c will be described as an example. Also, the addresses of all the terminal devices 6 accommodated in the TA3 are registered in the L-AFT 9 of each TA3, and no information is registered in the R-AFT10,
Each MAC frame 7 is assumed to be divided into two cells 8.

LA accommodated in ATM exchange A1a
Assuming that the N terminal device 6a has transmitted the MAC frame 7, the TAa 3a first receives the MAC frame 7. TAa 3a checks DA 71 “c” of MAC frame 7. Here, “c” of the DA 71 indicates the terminal device 6c. DA71 "c" is L-AFT9a, R
-Since it is not registered in either of the AFTs 10a,
An NQ cell 8a is created. VCI of the INQ cell 8a
Reference numeral 811 denotes “1” which is the VCI 811 corresponding to the TAa 3 a, “MID 812” denotes “0” indicating the INQ cell 8 a, and DA 821 denotes DA 7 of the MAC frame 7
1 “c”, SA822 of MAC frame 7
Set “a”. The TAa 3a transmits the INQ cell 8a set as described above to the ATM exchange A1a by broadcast VC, and broadcasts it to all other TA3s by the ATM exchange A1a and the other ATM exchanges B and C (1b, 1c).

Subsequently, the TAa 3a divides the MAC frame 7 to create a DATA cell 8c. The DAT
A VCI 811 corresponding to TAa is stored in the VCI 811 of the cell 8c.
11, “1”, the MID 812 has the DATA cell 8 c
A value “2” other than “0” or “1” indicating that there is a value is set. TAa3a is the DATA cell 8 set as described above.
a to the ATM exchange A1a by broadcast VC.
TM exchange A1a and other ATM exchanges B and C (1
b, 1c) to broadcast to all other TA3s.

The TAb, c (3b, 3c) receives the INQ cell 8a, but receives the DA821 of the INQ cell 8a.
Since "c" indicates the terminal device 6c, only the TAc 3c creates the ANS cell 8b. VC of ANS cell 8b
I811 has the same value "1" as the VCI 811 of the received INQ cell 8a, MID812 has the value "1" indicating that it is the ANS cell 8b, and DA821 has the same value "c" as the DA821 of the received INQ cell 8a. Set. Further, since the SA 822 of the INQ cell 8a is not registered in the R-AFT 10c, the SA 822 "a" is stored in the terminal address area 101c and the corresponding VCI 811
“1” is registered in the VCI area 102c. And A
The NS cell 8b is returned to the TAa 3a by the individual VC. AN
Since the S cell 8b is transmitted by the individual VC, the transmission side AT
The data is converted into the transmission source VCI “3” 811 by the M exchange C1c and arrives at the TAa 3a with the VCI 811 “3”.

The TAa 3a receives the ANS cell 8b, and divides the MAC frame 7 to create the remaining DATA.
In the cell 8c, the VCI 811 has the same value "3" as the VCI 811 of the received ANS cell 8b, and the MID 812.
"0" and "1" indicating that the cell is the DATA cell 8c.
Set a value other than "2". The ANS cell 8b
Is not registered in the R-AFT 10a, the DA 822 “c” is stored in the terminal address area 101.
a, and the corresponding VCI 811 "3" is registered in the VCI area 102a. Then, this DATA cell 8c
Is transmitted to TAc3c on the individual VC.

Since the above-mentioned DATA cell 8c is transmitted by the individual VC, the transmission source ATM exchange A1a transmits the data cell 8c.
I811 "1" is converted to TAc3c and VCI811
Arrives at "1".

TAc 3c assembles the received DATA cell 8c as shown in FIG.
Send to LAN.

Embodiment 3 FIG. Hereinafter, one embodiment of the third aspect of the present invention will be described with reference to the drawings. FIG. 7 is a diagram showing an R-AFT 11 in which a timer value area 103 is newly added to the R-AFT 10 of FIG. 1 used in claims 1 and 2. The present invention provides an R
Among the terminal addresses registered in the AFT 11, the terminal address that has not been in communication for a certain period of time is assigned to the R-AFT1.
1 is deleted.

Next, a specific operation will be described. A predetermined timer value is determined in advance, and the terminal address and the corresponding VCI 811 are registered or updated (when the MAC frame 7 is received from the LAN, the DA 71 of the MAC frame 7 is received).
Is already registered in the R-AFT 11, or receives the data cell 8c from the ATM network and sends it to the MA.
When the MAC frame 7 is assembled into the C frame 7, the SA 72 of the MAC frame 7 is already registered in the R-AFT 11).
3, and periodically subtracts all registered timer values. When the timer value becomes “0”, the terminal address corresponding to the timer value and the VCI 811 paired with the terminal address are deleted (actually,
To a terminal address value that means deletion).

[0047]

As described above, according to the first aspect of the present invention, a LAN separated into cells is provided between terminal adapters.
A broadcast-type logical connection that broadcasts a frame signal from one terminal adapter to all other terminal adapters and a point-to-point logical connection that establishes a one-to-one connection between the terminal adapters are set. A first address table holding addresses of all terminal devices connected to the accommodated LAN, an address of a terminal device accommodated by another terminal adapter, and a logical connection connecting the terminal adapter to the other terminal adapter. The terminal adapter has a second address table holding logical channel identifiers. When receiving a frame from the terminal, the terminal adapter checks the destination address in the frame against the address of the terminal device held in each table, and determines a predetermined address based on the check result. And a routine for processing When a cell is received from the M network, a routine for performing a predetermined process based on a result of collation between the type of the cell or the destination address in the cell and the terminal device address in the holding table is provided, so that the data cell received from the terminal adapter terminal can be processed. If the other terminal adapter to be transmitted cannot be specified, an inquiry cell is transmitted to all other terminal adapters by the broadcast-type logical connector, and each data cell constituting a frame by a point-to-point logical connection is transmitted to the terminal adapter responding to the cell. Since the transmission is performed to the terminal adapter, it is not necessary to perform the call control process at the time of transferring the frame, and there is an effect that the waiting time for transferring the frame can be reduced.

According to the second aspect of the present invention, between the terminal adapters, a broadcast-type logical connection for broadcasting a LAN frame signal decomposed into cells from one terminal adapter to all other terminal adapters; A point-to-point logical connection that connects the points one-to-one is set, and each terminal adapter
The first address table holding the addresses of all the terminal devices connected to the LAN accommodated therein, the address of the terminal device accommodated by another terminal adapter, and the logical connection connecting the present terminal adapter and the other terminal adapter. The terminal adapter has a second address table holding logical channel identifiers to be identified, and upon receiving a frame from the terminal, the terminal adapter compares the destination address in the frame with the address of the terminal device held in each table, and according to the matching result. If the terminal adapter accommodating the destination terminal device cannot be specified, the inquiry cell is transmitted to all other terminal adapters, and each of the divided data cells until a response cell is received from the other terminal adapter is also broadcast-type logical connection. So that the It is possible to shorten the transfer latency of the arm, there is an effect that it is possible to reduce the transfer delay time of the frame by shortening the transmission period of the data cell.

According to the third aspect of the present invention, a broadcast-type logical connection for broadcasting a LAN frame signal divided into cells between terminal adapters from one terminal adapter to all other terminal adapters, Each terminal adapter sets a point-to-point logical connection that connects the adapters on a one-to-one basis, and each terminal adapter has a first address table holding addresses of all terminal devices connected to the LAN accommodated therein, and other terminal terminals. An address of a terminal device accommodated by the adapter, a logical channel identifier for identifying a logical connection between the terminal adapter and the other terminal adapter,
The terminal adapter has a second address table provided with an area for holding a timer value, and when receiving a frame from the terminal, the terminal adapter collates the destination address in the frame with the address of the terminal device held in each table, A routine for performing a predetermined process based on the timer value, a routine for performing a predetermined process based on a comparison result between a cell type or a destination address in the cell and a terminal device address in a holding table when a cell is received from the ATM network, A routine for deleting from the table a terminal device that has not been in communication for a time exceeding the number of terminal devices that has not been in communication for a certain period of time among the terminal addresses registered in the second address table. By deleting the logical connection identification paired with the terminal address from the second address table, Without providing the area of the total number of terminal addresses in the address table, there is an effect that can be efficiently used in small areas.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a local address filtering table (L-AFT) and a mote address filtering table (R-AFT) provided in a TA.

FIG. 2 is a detailed format diagram of each cell.

FIG. 3 is a flowchart showing an operation when a TA receives a MAC frame from a LAN.

FIG. 4 is a flowchart showing an operation when the TA receives a cell from the ATM network.

FIG. 5 is an explanatory diagram showing how a cell is transmitted and changes in L-AFT and R-AFT in each TA in the invention of claim 1;

FIG. 6 is an explanatory diagram showing a state in which a cell is transmitted and a change in L-AFT and R-AFT in each TA in the invention of claim 2;

FIG. 7 is a configuration diagram of an R-AFT in which deletion processing can be performed in the invention of claim 3;

FIG. 8 shows a LAN using an ATM exchange constituting an ATM network.
FIG. 2 is a system configuration diagram in the case of performing inter-connection.

FIG. 9 is a configuration diagram of a MAC frame.

FIG. 10 is a configuration diagram of a cell.

FIG. 11 is a room configuration diagram showing a manner in which a TA divides a MAC frame into cells.

FIG. 12 is a room configuration diagram showing how a TA assembles a cell into a MAC frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ATM exchange 1a-1c 3 TA3a-3c 5 LAN line 6 Terminal device 6a-6c 9 L-AFT 10 R-AFT 11 R-AFT 103 with deletion function added Timer value area

Continuation of the front page (56) References JP-A-3-141754 (JP, A) JP-A-2-140034 (JP, A) IEICE Technical Report SSE89-40 (1889-7-19)

Claims (3)

(57) [Claims] In an ATM-to-LAN connection system in which a plurality of ATM exchanges constituting an ATM network connect terminal devices to a LAN via a terminal adapter, each of the plurality of ATM exchanges is connected to a cell in response to the terminal adapter. A broadcast-type logical connection that broadcasts the divided LAN frame signal from one terminal adapter to all other terminal adapters and a point-to-point logical connection that connects each terminal adapter one-to-one are set. Is a first address table holding the addresses of all the terminal devices connected to the LAN accommodated by the user, the address of the terminal device accommodated by the other terminal adapter, and the logic connecting the terminal adapter to the other terminal adapter. Logical channel identification to identify the connection The terminal adapter has a second address table holding the address and the address of the terminal device held in each table when receiving the frame from the terminal. And the terminal adapter adjusts the cell type when a cell is received from the ATM network.
If the cell is an inquiry cell, the address
Update the second address table if necessary
To return the response cell to the ATM network.
Discard the cell and if necessary the second
Updates the address table and returns data cells to the ATM network
If the cell is a data cell, assemble it into a frame
And a routine for transmitting data within the own LAN . 2. A method according to claim 1, wherein each of the plurality of ATM exchanges constituting the ATM network is divided into cells between the terminal adapters in a LAN-to-LAN connection system using an ATM network in which a LAN connected to a terminal device is accommodated via a terminal adapter. A broadcast-type logical connection for broadcasting the LAN frame signal from one terminal adapter to all other terminal adapters and a point-to-point logical connection for connecting each terminal adapter on a one-to-one basis are set. A first address table holding the addresses of all the terminal devices connected to the LAN accommodated therein, the addresses of the terminal devices accommodated by other terminal adapters, and the logical connection between the present terminal adapter and the other terminal adapter Logical channel identifier for identifying The terminal adapter has a second address table that holds the destination terminal device in the frame when receiving the frame from the terminal and compares the destination address in the table with the address of the terminal device held in each table, and accommodates the destination terminal device according to the result of the comparison. If it is not possible to identify the terminal adapter that is performing the transmission, the inquiry cell is transmitted to all other terminal adapters, and each divided data cell is also transmitted by the broadcast-type logical connection until a response cell is received from the other terminal adapter. A LAN connection method using an ATM network. 3. A broadcast-type logical connection for broadcasting a LAN frame signal divided into cells from one terminal adapter to all other terminal adapters, and a connection between the terminal adapters on a one-to-one basis. Set up a point-to-point logical connection
Each terminal adapter has a first address table holding addresses of all terminal devices connected to the LAN accommodated therein, an address of a terminal device accommodated by another terminal adapter, the present terminal adapter and the other terminal adapter. The terminal adapter has a second address table provided with an area for holding a logical channel identifier for identifying a logical connection connecting the terminal and a timer value, and the terminal adapter holds a destination address in the frame and each table when receiving a frame from the terminal. a routine for the predetermined processing by are collated the address of the terminal device, the verification result, Se
When receiving a cell from the ATM network, the timer value is
2 Register the address in the address table again, and
Value is periodically subtracted and the terminal adapter
Checks the cell type, and if the cell is an inquiry cell, the own L
If the address exists in the AN, the second address
Updates the stable cell and returns the response cell to the ATM network.
If the cell is a response cell, discard the interrogation cell.
If necessary, update the second address table and
The cell is returned to the ATM network, and if the cell is a data cell,
A routine that sends assembled to frame in its own LAN,
LAN connecting system by ATM network characterized by having a routine for deleting from the table with respect to the terminal apparatus was not in time communication to the timer value ing to zero.