JPS5834987B2 - Store and forward method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a store-and-forward system, and more particularly to a cooperative store-and-forward system in which messages do not disappear even if a failure occurs.

In data communications and facsimile communications, messages are transmitted from a transmitting terminal device to a receiving terminal device via a storage and switching device.

In the store-and-forward method, after the destination code (or selection signal) and data signal from the incoming line are stored in the exchange, an empty outgoing line is selected and these signals are sent to the next exchange, so the use of the outgoing line is reduced. Efficiency can be increased, and the storage function can be used to perform speed conversion, code conversion, format conversion, etc.

FIG. 1 is a block diagram of a general store and forward network.

The subscriber premises terminal device 1 is connected to a storage/exchange 3 via a subscriber cable 2, and this storage/exchange 3 is further interconnected via a relay transmission line 4 to an adjacent storage/exchange 3 at a higher level or at the same level.

In that case, in order to transmit the signal from the subscriber's premises terminal device 1 to the other subscriber's premises terminal device 1 designated by this subscriber, the storage/exchange 3 stores the signal in the message storage device in the exchange and then sends the signal to a predetermined number. The transmission path 4 is selected to transfer the message.

For example, a message is transferred from the Ai storage/exchange device 3 to the Ai storage/exchange device 3, then transferred to the Aj storage/exchange device 3, and then sequentially to the Ak storage/exchange device 3.

FIG. 2 is an explanatory diagram of a transfer method in the conventional store-and-forward system.

Now, the adjacent storage and exchange machines &i shown in FIG.

It is assumed that the messages A are transferred in the following order.

At the first time, in phase PH81, the message A stored in the storage device of the exchange 3 of Ai is read out and transferred as a time-series message signal 5 to the storage device of the exchange Aj via the relay transmission path 4. do.

When all of the message A has been transferred to the Aj exchange in the next phase PH82, the Aj exchange returns a control signal 6 to the Ai exchange indicating that the reception has been completed.

The Ai exchange receives the control signal 6 and erases the message A stored in the storage device.

Time phase P after a certain time has elapsed from phase PH82
In H83, the message A is transferred as a time-series signal 5 from the Aj exchange to the Ak exchange via the transmission line 4.

The operation in this case is Arashi i 2 in phase PH81
The operation is exactly the same as that between Arashi J exchanges.

In this way, the same operation is repeated to transfer message A to the designated subscriber premises terminal.

As is clear from FIG. 2, in the conventional transfer system, the number of exchanges that simultaneously store message A in the exchange network is one or two, and only when control signal 6 is returned in phase P)is2. sends message A at the same time on two exchanges.
, but in other phases only one exchange stores message A.

Therefore, if the exchange that stores messages malfunctions for some reason and the messages stored in the storage device disappear, the store-and-forward network will contain all the messages that subscribers have deposited for transmission. will no longer exist, and transfer to the other party will become impossible, causing a serious problem.

FIG. 3 is a configuration diagram of a conventional store and forward network.

In FIG. 3, a standby exchange 3' is installed at each exchange in order to prevent messages from disappearing from the exchange network due to a fault in the exchange.

In other words, in addition to the working exchange 3 that operates normally, there is also a standby exchange 3' that is operated in the event of a failure of this exchange 3.
In this way, each switching center is operated in parallel with duplex equipment.

FIG. 4 is a block diagram of one switching center in the switching network shown in FIG. 3.

As shown in FIG. 4, the working switching equipment 3 and the standby switching equipment 3' have a configuration including central processing units 3-1, 3-1', and main memory 3.
-2, 3-2', a line correspondence section 3-3, 3-3/, and message storage devices 3-4, 3-4'.
-5 interconnected.

As a result, even if a failure occurs in the device of the active exchange 3 and the messages in the message storage device 3-4 disappear, the same messages are stored in the message storage device 3-4' of the standby exchange 3'. Therefore, there is no problem in operation.

However, the method shown in Figure 4 has the disadvantage that each exchange requires duplex equipment, which increases the cost of the store-and-forward network, and requires multiple programs to run the exchanges in parallel. .

The purpose of the present invention is to eliminate such conventional drawbacks, and to provide a system in which even if a fault occurs in an exchange and the messages stored in its storage device are destroyed, there is no need to worry about the messages being lost in the store-and-forward network. Moreover, it is an object of the present invention to provide a highly reliable store-and-forward system against failures that does not require the installation of a standby system and does not complicate programs.

The store-and-forward system of the present invention is characterized in that the same message is always stored in two adjacent exchanges, and the message is transferred to the next exchange.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is an explanatory diagram of a transfer method in the store-and-forward system of the present invention.

Now, in FIG. 1, a message A is sent from the subscriber's premises terminal device 1 via the subscriber cable 2 to the subscriber exchange 3 of Ah, and further via the transmission line 4 to &i2&j
It is assumed that message A is sequentially transferred to each storage/exchange device 3 in 7A:.

At time phase PH8O when the subscriber terminal device 1 sends the message signal 5 to the Ah subscriber exchange 3 after the subscriber requests to send the message A, the Ah exchange 3 stores the message signal 5 (part of A) in the storage device. At the same time, the message signal 5' that has already been stored is sent to the adjacent exchange point i corresponding to the opposite subscriber.

In this way, immediately after the message A is sent from the subscriber's premises terminal device 1, the same message A is stored in each storage device of the adjacent exchanges 3 of Ah and Ai.

After the message A is accumulated in the exchange of Arashiri and A:i, in the time phase PH81, the message A stored in the storage device of the Arashii exchange 3 is read out and transmitted as a time-series message signal 5 to the relay transmission line 4. The data is transferred to the storage device in the exchange via the .

At time phase PH82 when the Ai exchange 3 has finished transferring all messages A to the Aj exchange 3, the Aj exchange 3 sends back a control signal 6 to the Ai exchange 3 indicating that the reception has been completed, and the Ai exchange that received this control signal 6 3 returns a control signal 6/ to the Ah exchange 3 to the effect that the Ganj exchange 3 has completed receiving the message A.

When the storm switch 3 receives the control signal 6', it erases the message A stored in the pre-storage device.

Time phase P after a certain time has elapsed from phase PH82
At H83, the &j exchange 3 transfers the accumulated message A to the next exchange 3 via the relay transmission line 4.

The operation is A: h A: in phase PH81.
i A j Same as exchanger 3.

After the transfer ends, in phase PH84 (not shown), control signals 6 and 6' indicating the end of transfer are sent gracefully from the exchange 3.
The data are sequentially returned to exchanger 3.

By repeating such operations, the message A is transferred to the designated subscriber premises terminal device 1.

As is clear from FIG. 5, in the transfer system of the present invention, there are two or three exchanges that simultaneously store messages A in the exchange network, and in phase PH82, control signals 6 and 6 are used.
When ' is returned, three exchanges have completely accumulated the message at the same time, but in other phases at least two exchanges have accumulated the same message A.

Therefore, in the store-and-forward network shown in FIG. 1, the amount of messages stored in the storage device of each exchange 3 is
Although the number is twice that of the conventional system, even if one exchange 3 in the network fails for some reason, messages kept from subscribers can be protected, and there is no need to worry about messages disappearing from the network.

Then, the message can be transferred to the designated subscriber terminal device 1 when the fault in the exchange 3 is repaired, or even if there is a detour route, even during the fault.

FIG. 6 is a block diagram of one storage and switching center according to the present invention.

As shown in FIG. 6, since one store and forwarding station of the present invention does not require duplication, all central processing units 3-
1. It is composed of a main memory 3-2, a line correspondence section 3-3, and a message storage device 3-40.

In that case, as the message storage device 3-40, conventional! It is sufficient to provide one with twice the capacity.

In FIG. 6, since there is no need for parallel operation, the program is simplified compared to the case of the conventional duplex configuration.

As explained above, according to the present invention, facsimile,
In the store-and-forward system used in data communications, the same message is stored in adjacent store-and-forward devices from the originating subscriber terminal device to the terminating subscriber terminal device.
Since the message is transferred to the next exchange on the route corresponding to the incoming subscriber terminal, there is no need to worry about the message being lost in the event of a failure, and reliability against failure is increased, and it is necessary to provide a backup system at each exchange. Since there is no , it is possible to reduce costs and simplify programs.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a general store and forward network, Figure 2 is an explanatory diagram of the transfer method of the conventional store and forward system, Figure 3 is a configuration diagram of a conventional store and forward network, and Figure 4 is the same as that of Figure 3. FIG. 5 is an explanatory diagram of a store-and-forward transfer method showing an embodiment of the present invention. FIG. FIG. 1: subscriber premises terminal equipment, 22 subscriber cable 3: storage exchange, 4: relay transmission line, 5, 5': message signal,
6, 6': Control signals, 3-1, 3-1': Current and backup central processing units, 3-2, 3-2': Current and backup main memories, 3-3, 3-3': Working and standby line correspondence units, 3-4, 3-4': Working and standby message storage devices, 3-40: Message storage device with twice the capacity.

Claims (1)

[Claims] 1 In a store-and-forward network in which a message signal from an originating subscriber's premises terminal equipment passes through multiple storage exchanges, selects an available line, and transfers it to a terminating subscriber's premises terminal equipment, the same message is sent to two adjacent storage exchanges. The message is stored simultaneously from one of the two storage exchanges to the next exchange on the path corresponding to the called subscriber's premises terminal equipment, and when a control signal indicating the end of transfer is returned, the message is stored at the other one. A store-and-forward method characterized by erasing the messages stored in the exchange.