JPS6336701B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data exchange system, and particularly to a data exchange system in a virtual circuit type data exchange network.

In a data switching network, a so-called virtual circuit system is used, like a packet switching network, in which terminal devices to be communicated are connected to each other via a virtual line, and data is transmitted based on information that identifies the virtual line. has been adopted.

Such a data switching network is composed of a plurality of data switching devices, such as a packet switching device in a packet switching network.

FIG. 1 is a diagram showing a packet switching network that is an example of the subject of the present invention. In FIG. 1, it is assumed that a call is set up between terminal devices A and B accommodated in a packet-switched network PN, and data communication is in progress. Terminal device A
An example of a conventional configuration of a packet switching system PS1 accommodating a packet switch PS1 is shown in FIG. In FIG. 2, a central processing unit CPU, a main memory unit MM, and a line control unit CCU that connects lines etc. to a packet switch PS2 accommodating terminal devices A and B are connected via a common bus BUS. There is. The switch number SN1 assigned to the packet switch PS1 is stored in the area A1 of the main storage device MM, and the switch number SN1 assigned to the packet switch PS1 is stored in the area A2.
The line number AN etc. of the terminal device A etc. accommodated in 1 is stored. Furthermore, for a terminal device (for example, A) with a high communication ability that allows calls to be set up with multiple terminal devices at the same time, an area (for example, A3) are provided respectively. Terminal device A connects terminal device B with logical channel number LCA1.
If a call is being set up, area A stores call identification information regarding terminal device B, that is, switch number SN2, line number BN, and logical channel number LCB1, in logical channel number LCA1 of area A3.
4 are combined. Similarly, in the packet switching system PS2 accommodating terminal device B, call identification information regarding terminal devices A and B is stored in a main storage device (not shown). Next, an example of the process of disconnecting a call that is being set up between terminal devices A and B will be explained with reference to FIG. In FIG. 3, when data transmission a between terminal devices A and B is completed based on the call that is being set up, terminal device A makes a disconnection request in order to disconnect the call that is being set up. Send signal b to packet switch PS1. The packet switch PS1 that has received the disconnection request signal b transfers the disconnection request signal c to the packet switch PS2 associated with the call. The disconnection request signal c is sent to the packet switch PS.
2, the packet switch PS2 sends a disconnection instruction signal d to the terminal device B.
Terminal device B, which has received the disconnection instruction signal d, returns a disconnection confirmation signal e to the packet switch PS2 to recover. The packet switch PS2, which has received the disconnection confirmation signal e, clears the call identification information stored in the main memory MM and sends a disconnection response signal f to the packet switch PS1. The packet switching system PS1, which has received the disconnection response signal f, also clears the call identification information stored in the main memory device MM and transfers the disconnection response signal g to the terminal device A. Due to the above,
Terminal equipment A is restored, and the call set within the packet switching network PN is completely disconnected. During the above process, a failure occurs in the transmission path from packet switch PS1 to PS2, and packet switch PS
1 sends the disconnection request signal c to the packet switch PS.
2 cannot be received, the packet switch
PS2 does not perform any call disconnection processing as described above,
A disconnection response signal f is not sent to the packet switch PS1. After the packet switch PS1 transfers the disconnection request signal c, the packet switch PS1 closes the connection within a certain period of time T.
If the disconnection response signal f cannot be received from PS2,
A pseudo disconnection response signal g' is generated and sent back to the terminal device A for recovery, and the call identification information stored in the main memory device MM is deleted.

As is clear from the above explanation, in a conventional data exchange system, the terminal device A and the packet switch PS1 disconnect the call that is being set up, but the packet switch PS2 cannot receive the disconnection request signal c, so it disconnects the call that is being set up. Assuming that the call is still ongoing,
There is no need to restore terminal device B. the result,
Calls set up within the packet-switched network PN remain incomplete, and the packet-switched network
The constituent resources of the PN are held invalid (hereinafter, calls remaining in such an incomplete state will be referred to as residual calls).

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional data exchange system as described above, and to minimize the possibility of a data exchange network being held invalid due to residual calls caused by transmission path failures or the like.

This purpose consists of multiple data exchangers,
In a data exchange network that performs call control based on the virtual circuit system, a data exchange receives a disconnection request signal regarding a call that is being set up from an accommodating terminal device, and the data exchange After transmitting the disconnection request signal to
Residual call information storage means for storing identification information regarding the call held by the data exchange in a residual call area provided within the data exchange when it is detected that a disconnection response signal is not returned from the other data exchange within a predetermined time. and a residual call area reference means that refers to the residual call area at a predetermined cycle; On the other hand, when the residual call disconnection signal transmitting means for transmitting the residual call disconnection signal and the destination data exchange that has received the residual call disconnection signal receive a residual call disconnection response signal to be sent back to the data exchange, the call is disconnected. This is achieved by providing residual call disconnection means for performing processing.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6. FIG. 4 is a diagram showing the configuration of a packet switch according to an embodiment of the present invention, FIG. 5 is a diagram showing a call disconnection process according to an embodiment of the present invention, and FIG. FIG. 3 is a diagram illustrating an example of a residual call disconnection signal that is used. In FIGS. 4 to 6, the same reference numerals as in FIGS. 1 to 3 indicate the same objects. Packet switch PS1 shown in Figure 4
The difference from that in Figure 2 is that the main memory MM
A residual call area A5 is provided in the packet switch PS1, and a residual call information storage function (not shown) is provided in the packet switch PS1.
It is equipped with a residual call area reference function, a residual call disconnection signal transmission function, and a residual call disconnection function.
When a call is set up between terminal devices A and B in FIG. 1, the call identification information for terminal device A is stored in areas A1, A2, A3, and A4 of the main memory device MM in FIG. 4, as in FIG. 2. Information (switch number SN1,
A line number AN, logical channel number LCA1) and call identification information regarding terminal device B (exchange SN2, line number BN, logical channel number LCB1) are stored. In FIG. 5, when data transmission a between terminal devices A and B ends based on the call that is being set up, terminal device A sends a disconnection request signal b to the packet as in FIG. Exchange PS
Send to 1. Assume that when the packet switch PS1, which has received the disconnection request signal b, transfers the disconnection request signal c to the packet switch PS2, the packet switch PS2 is unable to receive the disconnection request signal c due to a transmission path failure or the like. The packet switch PS2 does not perform any call disconnection processing and does not forward the disconnection response signal (FIG. 3f) to the packet switch PS1. If the packet switch PS1 cannot receive the disconnection response signal f from the packet switch PS2 within a certain time T after transmitting the disconnection request signal c, it creates a pseudo disconnection response signal g' and sends it back to the terminal device A. At the same time, the call being set up is regarded as a residual call, the residual call information storage function is activated, and the call identification regarding terminal devices A and B stored in areas A2, A3, and A4 in the main memory device MM is executed. The information is stored in the residual call area A5 as residual call information. In the packet switch PS1, the residual call area reference function scans the residual call area A5 at a constant period T (for example, 1 minute) to check the presence or absence of stored residual call information. The residual call area reference function detects that residual call information regarding the residual call is stored;
The residual call information is transmitted to the residual call disconnection signal transmission function. The residual call disconnection signal transmission function creates a residual call disconnection signal h based on the received residual call information and sends it to the packet switch PS2. The residual call disconnection signal h has a configuration as shown in FIG. 6, includes a residual call display section indicating that the signal is related to a residual call in addition to the residual call information, and is separated by a start pattern and a termination pattern. There is. When the residual call disconnection signal h is sent for the first time, if the transmission path has not been repaired yet, the packet switch PS
2 cannot receive the residual call disconnection signal h and does not show any reaction to the packet switch PS1. The residual call area reference function of the packet switch PS1 repeats the above-mentioned process after a certain period T has elapsed, and the residual call disconnection signal transmitting function sends a residual call disconnection signal h to the packet switch PS2. This time the transmission line has been repaired,
The residual call disconnection signal h is reliably sent to the packet switch PS.
Delivered to 2. When the packet switch PS2 receives the residual call disconnection signal h, it activates the residual call disconnection function. The residual call disconnection function identifies disconnection of the call being set up between terminal devices A and B based on the received residual call disconnection signal h, creates a disconnection instruction signal d, and sends it to terminal device B. Terminal device B, which has received the disconnection instruction signal d, returns a disconnection confirmation signal e in the same manner as in FIG. The packet switch PS2, which has received the disconnection confirmation signal e, clears the call identification information stored in the main memory MM and sends a residual call disconnection response signal i to the packet switch PS1. The packet switch PS1, which has received the residual call disconnection response signal i, activates the residual call disconnection function. The residual call disconnection function cancels all call information and residual call information stored in each area A1 to A5 in the main memory device MM. As a result of the above, the remaining calls existing within the packet switching network PN are completely disconnected.

As is clear from the above explanation, according to this embodiment, the packet switch PS1 sends out the residual call disconnection signal h at a constant period T until the residual call that has occurred is disconnected, and as soon as the transmission path is repaired, the residual call disconnection signal h is sent out. Leads to disconnection of remaining calls.

Note that FIGS. 4 to 6 are only one embodiment of the present invention, and, for example, the terminal devices A and B are not limited to those equipped with a plurality of logical channels, and can only make a single call at the same time. Even if the settings cannot be made, the effects of the present invention remain unchanged. If so,
Areas A3 and A4 in main memory device MM in Figure 4
The logical channel numbers LCA1 and LCB1 stored in the LCA1 and LCB1 do not exist. Also a packet switch
The configuration of PS1 is not limited to that shown in FIG. 4, and many other modifications may be considered.
In either case, the effects of the present invention remain the same. Further, the cause of residual calls is not limited to a transmission line failure, and many other causes such as failure of the packet switch PS1 or PS2 can be considered, but the effects of the present invention remain the same in either case. Further, the data exchange network to which the present invention is applied is not limited to a packet exchange network, and the effects of the present invention will remain the same even if applied to other data exchange networks that employ a virtual circuit system.

As described above, according to the present invention, residual calls occurring in a virtual circuit data exchange network can be quickly disconnected, and invalid hold due to residual calls in the data exchange network is reduced to a minimum.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a packet switching network to which the present invention is applied, FIG. 2 is a diagram showing an example of the configuration of a conventional packet switch, and FIG. 3 is a diagram showing an example of a conventional call disconnection process. FIG. 4 is a diagram showing the configuration of a packet switch according to an embodiment of the present invention, FIG. 5 is a diagram showing a call disconnection process according to an embodiment of the present invention, and FIG. It is a figure which shows an example of a call disconnection signal. In the figure, PN is a packet switching network, PS1 and PS2 are packet switches, A and B are terminal devices, CPU is a central processing unit, MM is a main memory,
CCU is a line control unit, BUS is a common bus, A1 to A4 are areas, A5 is a residual call area, SN1 and
SN2 is the exchange number, AN and BN are the line numbers,
LCA1 and LCB1 are logical channel numbers, a is data transmission, b and c are disconnection request signals, d is disconnection instruction signal, e is disconnection confirmation signal, f, g and
g′ is the disconnect response signal, i is the residual call disconnect response signal, h
indicates a residual call disconnection signal, and T indicates a predetermined time (period).

Claims (1)

[Scope of Claims] 1. In a data exchange network that is composed of a plurality of data exchangers and performs call control based on a virtual circuit system, the data exchanger receives a disconnection request signal regarding a call that is being set up from an accommodating terminal device. and upon detecting that a disconnection response signal is not returned from the partner data exchange within a predetermined time after transmitting the disconnection request signal to the partner data exchange that accommodates the partner terminal device that is currently setting up the call; residual call information storage means for storing identification information regarding the call held by the data exchange in a residual call area provided in the data exchange; and residual call area reference means for referencing the residual call area at a predetermined cycle. and residual call disconnection which, when the residual call area reference means detects the identification information stored in the residual call area, sends a residual call disconnection signal to the partner data exchange corresponding to the identification information. signal transmitting means; residual call disconnection means for performing call disconnection processing when the partner data exchange that has received the residual call disconnection signal receives a residual call disconnection response signal that is returned to the data exchange; A data exchange method characterized by providing.