JPH0454748A - Interconnection system among local area networks by means of asynchronous transfer mode network - Google Patents

Abstract

PURPOSE:To reduce the transfer wait time of a MAC frame by sending a DATA cell to a path decided through the communication with other terminal adaptor(TA) by one TA in the case of transmission of the DATA cell which is generated through the division of the MAC frame by the one TA. CONSTITUTION:Each of TAs 4a-4h receives all MAC frames sent from each of terminal equipments 5a-5h. When a destination address in the received MAC frame represents a terminal equipment of a LAN accommodated in other ATM exchange, each TA broadcasts an inquiry cell including the destination address in the MAC frame to all the other TAs. When the address represents an address of a terminal equipment, each TA returns an acknowledge cell to the TA having sent the cell. When the destination address in the inquiry cell does not indicate the said address, the inquired cell is aborted. The TA receiving the acknowledge cell sends a cell generated through the division of the MAC frame to the TA having sent the acknowledge cell. The TA receiving the cell sends the MAC frame to the LAN to which the TA belongs.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses an asynchronous transfer mode (hereinafter referred to as ATM) for communication between terminal devices connected to different local area networks (hereinafter referred to as LAN). AT that connects each LAN using the ATM switch that makes up the network
This is an indirect LAN system using M network.

[Conventional technology]

FIG. 3 is a system configuration diagram of a conventional LAN indirect type system using an ATM network. In the figure, reference numerals 1a to 1d indicate ATM switching equipment that divides data into fixed length data units called cells and exchanges data in units of cells. Reference numeral 2 denotes an ATM line that connects each of these ATM exchanges 1a to 1d to form an ATM network.

3 is a LAN line (F) of one or more LANs accommodated in each ATM exchange 1a to 1d, and 4a to 4h are terminal adapters (hereinafter referred to as TA) installed as nodes on each LAN line 3. It is.

The LAN by each LAN line 3 is connected to each TA4a to 4h.
It is accommodated in any of the ATM exchanges 1a to 1d via the ATM switch 1a to 1d. 5a to 5h are terminal devices connected to any of the LAN lines Is3, and 6 is arranged as a node on each LAN line 3 to connect each of these terminal devices 5a to 5h to the corresponding LAN line 3. It is a transmission device.

Here, in the following explanation, the ATM exchange 1a"1
d, T A 4a to 4h, and terminal devices 5a to 4h.
5h refers to one representatively without specifying it,
ATM exchange 1, TA4. It will be described as a terminal device 5.

FIG. 4 shows the structure of a media access control (hereinafter referred to as MAC) frame T flowing on the LAN line 3. The MAC frame 7 consists of a destination address 71, a source address 72, and an information section T3. ing. FIG. 5 shows the configuration of a cell 8 transmitted to the ATM line 2. The cell 8 is a pseudo channel identifier (
It consists of a header part 81 including a VCI (hereinafter referred to as VCI) 811 and an information part 82.

Next, the operation will be explained. Now, assume that, for example, a call is made from the terminal device 5a to the terminal device 5h.

First, the MAC frame 7 transmitted by the terminal device 5a
is transmitted to the LAN line 3 via the transmission device 6. T.A.
4a receives the MAC frame 7 from the LAN line 3 and inspects the destination address 71 of the received MAC frame 7.

As a result of the check, if the destination address 71 indicates the address of the terminal device 5 within the LAN accommodated in the own ATM switch 1a, the received MAC frame 7 is discarded. In this case, since the destination address 71 does not indicate the address of the terminal device 5 within the LAN accommodated in the own ATM switch 1a,
L to which the terminal device 5h with the destination address 11 is connected
Check which TA4 is connected to the AN, and check the received M
TA4h to which AC frame 7 should be transmitted is determined.

Next, the TA 4a makes a call to the ATM exchange 1a, and the ATM exchange 1a that receives the call makes a call to the ATM exchange 1d to which the TA 4h to be transmitted is connected. And both A
The TM exchanges 1a and 1d set a route so that the cell 8 is transferred to the ATM exchange 1d on the receiving side.

Additionally, TA4h acquires VCl311 and M
dividing the AC frame 7 into one or more cells 8 of a certain length;
The cell 8 is connected to ATM switch 1a, ATM line 2゜ATM
The message is transmitted to the other party's TA4h via the exchange 1d. 6th
The figure is an explanatory diagram showing the division of this MAC frame 7.
In this case, the MAC frame 7 is divided into three parts, each of which is used as the information part 82 of each cell 8, and the information part 82 is filled with the VCI.
The cell 8 is formed by adding a header section 81 including 811.

The TA 4h on the receiving side assembles a MAC frame 7 from the cells 8 received in sequence and transmits it to the LAN line 3. 7th
The figure is an explanatory diagram showing the assembly of this MAC frame 7. Each information section of three cells 8 is taken out and connected in a predetermined order to assemble the MAC frame 7. This MAC frame 7 is sent to the terminal device 5h indicated by the destination address 71.
received at

When all the cells 8 of one MAC frame 7 have been transmitted, the transmitting side TA 4a disconnects the call, and the ATM switch 1a releases the route.

In addition, regarding such a conventional LAN indirect indirect system using an ATM switch, for example, the Institute of Electronics, Information and Communication Engineers Technical Research Report SSE 89-4 Or Study of LAN Connection ATM and MAN Adaptation Functions (Institute of Electronics, Information and Communication Engineers) It is described in detail in the Society (published July 19, 1989).

[Problem to be solved by the invention]

Since it is configured as in the conventional LAN indirect indirect method using an ATM network, the ATM switch 1 has one MAC
It is necessary to perform call control processing for each frame to set and release the transmission route of cell 8, and the processing load is heavy.
The waiting time for transmitting the MAC frame 7 due to call control processing is extremely long, and the TA4 is connected to the L to which the destination terminal device 5 is connected.
It is necessary to have information for determining the TA4 connected to the AN, and when there are many terminal devices connected to the LAN,
There were issues such as having to have a huge amount of information.

The present invention was made to solve the above-mentioned problems. It is not necessary to perform call control processing when transferring a MAC frame, and it is possible to shorten the transfer waiting time of a MAC frame. The purpose of this invention is to provide a LAN indirect indirect system using an ATM network that does not require information that associates a TA connected to a LAN to which the terminal device is connected.

[Means to solve the problem]

In the LAN VIM connection system using an ATM network according to the present invention, a call for transmitting cells is set up in advance between multiple TAs, and each TA receives all MAC frames transmitted by each terminal device connected to the LAN to which the TA is connected. If the destination address in the received MAC frame indicates a LAN terminal device accommodated in another ATM switch, it broadcasts an inquiry cell containing the destination address in the MAC frame to all other TAs. , each TA refers to the destination address of the inquiry cell, and if this address indicates the address of a terminal device connected to the LAN to which that TA is connected, it returns a response cell to the TA that sent the inquiry cell, and returns the response cell to the TA that sent the inquiry cell. If the destination address does not indicate the address of a terminal device connected to the LAN to which the TA is connected, the inquiry cell is discarded, and the TA that receives the response cell sends a cell created by dividing the MAC7 frame to the TA that sent the response cell. The TA that receives the cell assembles a MAC frame from the received cell and transmits a MAC7 frame to the LAN to which the TA is connected.

[Effect]

The TA in this invention does not perform call control when transmitting cells created by dividing a MAC frame, but determines a route by simply interfering between inquiry cells and response cells, and transmits cells created by dividing a MAC frame.
By transmitting cells created from C frames to other TAs, the processing load can be reduced compared to the conventional method, and the waiting time for transmitting cells created from MAC frames can be shortened. It is not necessary to have information for determining the TA connected to the LAN connected to the LAN.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Here, the system configuration of the LAN-to-LAN connection system using the ATM network according to the present invention is equivalent to the conventional system shown in FIG.

FIG. 1 shows an LA network using an ATM network according to an embodiment of the present invention.
FIG. 2 is a sequence diagram showing the transmission sequence of each cell transmitted on the N-indirect indirect method system, and FIG. 2 is a format configuration diagram showing the detailed format of each cell. In FIG. 1, 1a to 1d I/i ATM exchanges,
4m-4h are the TA, 7 is the MAC frame, 71 is the destination address, and 72 is the source address, which are the same or equivalent parts as those given the same reference numerals in FIGS. 3 and 4. Here, FIG. 1 illustrates a case where TA4m is the source and TA4h is the destination.

In addition, in FIGS. 1 and 2, 8a is the source T
This is an inquiry cell (hereinafter referred to as an INQ cell) transmitted from A4a to all other TA4b to TA4h, and 6. ab
is a response cell (hereinafter referred to as an ANS cell) returned by the destination TA 4h to this INQ cell 8a. 8c is a cell (hereinafter referred to as a DATA cell) created by dividing the MAC frame 7 to be sent to the destination TA 4h by the source TA 4a which received the ANS cell 8b.

81 is INQN and cell%ANs #8b, and DAT
82 is the header part of the A cell 8c, and 82 is the header part of the A cell 8c.
This is the information section of ~8c. 811 /li each cell 88-8
The VCI included in the header section 81 of cell 81 is equivalent to the one with the same reference numerals in FIG.
This is a multiplexing identifier (hereinafter referred to as MID) included in the header section 81 of a to 8c. 821 is the MID (hereinafter referred to as MIDd) included in the information section 82 of the INQ cell 8a and the ANS cell 8b, and 822 is the destination address included in the information section 82 of the INQ cell 8a.

Next, the operation will be explained. It's the LAN terminal device 5a currently housed in the ATM switch 1a! , M addressed to the LAN terminal device 5h housed in the ATM switch 1d.
Assume that AC frame 7 is transmitted. The MAC frame 7 is sent to the LAN line 3 via the transmission device 6, and
A4a first receives this MAC frame 7 and examines the contents of the destination address 11 of the received MAC frame 7. At this time, the content of the destination address 11 is "h" indicating the terminal device 5h.

TA4a is the destination address 7 of the received MAC frame 7.
1 is not the address of the terminal device 5 connected to its own LANK, the MID value is assigned to the MAC frame 7. Now, the assigned MIDm is “
2". Next, start creating the INQ cell 8a,
The VCI 811 of the INQ cell 8a indicates "A" indicating TA4a, and the MID 812 indicates that the cell is the NQ cell 8a.
"0" indicating that
The content "h" of the destination address 71 of the MAC frame 7 is set in the MID value 12' destination address 822 assigned to the frame 7.

TA4m ATs the INQ cell 8a created as above.
M exchange 1a and all other TA4b to this ATM exchange 1a and other ATM exchanges 1b to 1d.
Broadcast from ~4h.

Each of the TAs 4b to 4h checks the destination address 822 of the received INQ cell 8a, and if the LAN K to which they are connected indicates the address of the terminal device 5 to be connected, then the ANS
Create cell 8b. Now, the destination address 822 is 'h''
Since terminal device 5h is shown, only TA4h is A.
Create NS cell 8b. That is, the ANS cell 8 b (
DVCI 811 K is “H” indicating TA4h, MID
812 is “1” indicating that the cell is the ANS cell 8b, MIDd 821 is the received INQ cell 8a.
The same value “2” as MIDd 821 is set. After that, the value of VCl 311 of the received INQ cell 8a is “A”
It identifies that the source of the INQ cell 8a is the TA4m, and returns the created ANS cell 8b to the TA4m.

TA4aFi that received the relevant ANS cell 8b, its MI
From Dd 821 and VC'IJHI, it is determined that MAC7 frame 7 to which MID value "2" has been assigned should be transmitted to TA4h. As a result, the TA 4a creates a DATA cell 8c in the same manner as in the conventional case shown in FIG. 6, and transmits it to the TA 4h. Here, "A'" indicating TA4m, MI
D812 has the MI assigned to MAC frame 7.
Set the D value to 12''.

Receive TA4hFi and assemble 8c in 7'jDATA as in the conventional case shown in Figure 7 to create MAC frame 7.
and sends it to LAN line 3. This MAC frame 7 is transmitted through the LAN line 3, and its destination address 1
It is received by the terminal device f5h indicated by 1.

〔Effect of the invention〕

As described above, according to the present invention, when a TA transmits a DATA cell created by dividing a MAC frame, it is possible to exchange simple INQ cells and ANS cells with other TAs. Determine the route by and use the DAT
Since the configuration is configured to transmit A cells, there is no need to perform call control processing when transmitting MAC frames.
It is possible to shorten the transfer waiting time of AC frames, and at the TA, the address of the destination terminal device and the ATM that accommodates the LAN to which the destination terminal device is connected.
AT that eliminates the need for information to associate with exchanges
This has the effect of providing an indirect LAN connection method using the M network.

[Brief explanation of the drawing]

FIG. 1 shows an LA network using an ATM network according to an embodiment of the present invention.
FIG. 2 is a sequence diagram showing the transmission sequence of each cell in the N-direction line connection system. FIG. 2 is a format configuration diagram showing the detailed format of each cell. FIG.
A system configuration diagram showing the system configuration of a LAN indirect line connection system using a TM network. Fig. 4 is a format configuration diagram showing the format of a MAC frame transmitted on the LAN line. Fig. 5 is a system configuration diagram showing the format of a MAC frame transmitted on the LAN line. A format configuration diagram showing the format, Figure 6 is an explanatory diagram showing the division of a MAC frame into cells, and Figure 7 is a diagram showing the division of the MAC frame into cells.
It is an explanatory view showing assembly into a frame. 1a to 1d are ATM exchanges, 3 is a LAN line, 4a to 4
h is TA, 5a to 5h are terminal devices, 7 is MAC frame, 71.822 is destination address, 8 is cell, 8a is IN
Q cell, 8b is an ANS cell, and 8c is a cell created by dividing the MAC7 frame (DATA cell). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent Applicant Mitsubishi Electric Co., Ltd. Agent Patent Attorney 1) Hiroshi Sawa (2 others)

Claims (1)

[Claims] A plurality of asynchronous transfer mode switches constituting an asynchronous transfer mode network accommodate local area networks via terminal adapters installed as nodes on each local area network, each terminal adapter having a segment a media access control frame received from said local area network into one or more cells and send it to the asynchronous transfer mode switch to which it is connected; When the cell is received, the cell is transferred to the asynchronous transfer mode switch that accommodates the local area network to which the terminal device having the destination address specified in the media access control frame is connected, and the cell is is received from another asynchronous transfer mode switch, the terminal device transfers the cell to a terminal adapter of a local area network to which the terminal device is connected, and each terminal adapter assembles the cells received from the asynchronous transfer mode switch. In a local area network connection method using an asynchronous transfer mode network in which a media access control frame is created and transmitted to a connected local area network, a call for transmitting the cell between the plurality of terminal adapters is set in advance. , each of the terminal adapters receives all the media access control frames transmitted by each terminal device connected to the local area network to which the terminal adapter is connected, and the destination address in the media access control frame is different from other asynchronous If it indicates a terminal device connected to a local area network accommodated in a transfer mode switch, it broadcasts an inquiry cell containing the destination address in the media access control frame to all other terminal adapters, and Each terminal adapter that received the inquiry cell refers to the destination address of the inquiry cell, and if it indicates the address of a terminal device connected to the local area network to which the terminal adapter is connected, the inquiry cell is sent. The response cell is returned to the terminal adapter, and if it does not indicate the address of the terminal device, the inquiry cell is discarded, and the terminal adapter that received the response cell transmits the media access control frame to the terminal adapter that sent the response cell. The terminal adapter that receives the cells assembles a media access control frame from the received cells and transmits the media access control frame to the local area network to which the terminal adapter is connected. A connection method between local area networks using an asynchronous transfer mode network, which is characterized by transmitting .