JPH0974411A - Call control system - Google Patents

Abstract

(57) Abstract: A call control method for reliably preventing erroneous recognition of call connection information due to loss of information in units of cells when a receiving side device receives cellized call connection information. SOLUTION: Call connection information from a terminal device 12a is sent from a switch 11a to a voice CLAD 10a, where it is converted into cells and transmitted to an ATM network 1. This cell is received by the voice CLAD 10b, disassembled (disassembled into cells), and transmitted to the exchange 11b. The exchange 11b selects the terminal device 12b housed therein by the call connection information. If this call connection information is lost in cell units due to ATM network congestion, etc., the voice CLAD 10b
Therefore, there is a possibility that the call connection information cannot be restored and the exchange 11b receives the incorrect call connection information and selects another terminal device. To prevent this, when cell discard occurs at the time of receiving the call connection information, the originating device is notified that cell discard occurs and normal connection cannot be established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cell-based transmission target information, for example, an ATM (asynchrous transfer module).
e) The present invention relates to a call control method between a transmitting side device and a receiving side device when transmitting via a network.

[0002]

2. Description of the Related Art As a conventional technique of this kind, for example, an "input traffic control method" described in Japanese Patent Laid-Open No. 4-345241 is known. This method is intended to control the traffic of the calling terminal by utilizing the fact that the call control cell in the line accommodating module can be easily identified in the communication system by the ATM exchange.

FIG. 4 is a configuration diagram for realizing this method. Referring to FIG. 4, the received cell, which is the transmission data, is separated into a call control cell and user information by the call control cell separation unit 21, and the user information is transferred to the line accommodation module coupling device 22 and is then used for the purpose. Is switched to the route. In addition, the call control cell is transferred to the signal processing unit 23, and after being identified as a call control frame, the congestion control unit 231 measures the arrival density of the frame. When the measured value exceeds the specified value, the newly arrived call control frame is discarded without being delivered to the call control unit 24, and a disconnection instruction or call acceptance refusal frame is created and sent to the calling terminal. I am sending it back.

[0004]

As described above, conventionally, the call connection information, specifically, the arrival density of the call control frame is measured, and when the measured value exceeds a predetermined specified value, The traffic volume is controlled by discarding subsequent call control frames and returning information indicating a disconnection instruction or refusal of acceptance to the calling terminal. Therefore, if any uncorrectable error occurs when the cell passes through the ATM network or the transmission line, the cell is discarded and the call connection information cannot be correctly reproduced. In particular, a terminal having only one call control frame cannot correctly recognize the call connection information even if the cell discard is detected on the receiving side. However, the conventional method cannot prevent such a situation.

In view of the above conventional problems, an object of the present invention is to provide a call control system capable of reliably preventing erroneous recognition due to a lack of cell units of call connection information.

[0006]

The call control system of the present invention comprises:
The call connection information included in the transmission data is transmitted between the devices equipped with cell assembling / disassembling means for converting the transmission data into cells and transmitting the cells to the transmission line, and disassembling the cells received from the transmission line to extract the transmission data. In a method of establishing a call between a calling side device and a receiving side device based on the message information, the cell assembling / disassembling means of the receiving side device generates predetermined message information indicating a distinguishable state from a call connectable state. And a call state monitoring unit that monitors the presence or absence of cell discard in the call connection information, and returns the message information to the originating device when the cell discard of the call connection information is detected. Characterize. Further, the calling side device is provided with means for releasing the call by performing a disconnection process with the transmission line upon receiving the message information.

In the prior art, the traffic control of the originating device is performed by counting the number of arrivals of call connection information. In the call control method of the present invention, the call connection is correctly executed when the cell discard is detected. When it is determined that the connection cannot be made, the reception side device returns message information indicating that connection is impossible to the transmission side device. The transmission side device releases the call upon receiving this message information, and retransmits the transmission data if necessary. In this way, it is possible to prevent erroneous recognition due to the loss of call connection information in cell units.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an example of a transmission system using a voice CLAD (cell assembly / disassembly) as a cell assembly / disassembly means. Referring to FIG. 1, A
Two voice CLADs 10a and 10b are connected via the TM network 1, and the first voice CLAD 10a is connected to a first exchange 11a accommodating a terminal device 12a having a call connection function. On the other hand, to the second voice CLAD 10b, a second exchange 11b that accommodates a terminal device 12b having a call connection function is connected. In this way, a pair of transmission devices is constructed.

A voice CLAD 10a provided in each transmission device,
10b have the same configuration, and as shown in FIG. 2, an AAL1 (ATM adaptation layer-type 1) processing unit 101, a call status monitoring unit 102, a transmission data selection unit 103, a connection failure message generation unit 104, And a channel selection control unit 105. The channel selection control unit 105 may be provided separately from the exchanges 11a (11b), and thus can be configured separately from the voice CLADs 10a and 10b.

The AAL1 processing unit 101 uses the ITU-T (TEL
ECOMMUNICATION STANDARDIZATION SECTOR OF INTERNATI
ONAL TELECOMMUNICATION UNION) Recommendation, I. As stipulated in 363, the cell assembly, the cell disassembly, or the cell discard is recognized. Specifically, at the time of calling, the ATM network 1 converts the connection impossible message into cells.
When a cell discard is recognized, the cell discard information is generated and output when the cell discard is recognized.

The call status monitoring unit 102 includes an AAL1 processing unit 1
The call control frame output from 01 is constantly monitored to generate and output call status information. The call status includes idle / connection phase / call status, as shown in FIG. Call establishment is performed in the connection phase, and after the call is established, a call with the partner terminal becomes possible. The transmission data selection unit 103 selects data to be transmitted and outputs it to the AAL1 processing unit 101. The unconnectable message generating unit 104 sends message information that can identify the unconnectable state, for example, a busy tone, an alarm sound, or text data to the sending data selecting unit 103. The channel selection control unit 105 uses the exchange 11a,
Set the channel to connect to 10b and set CL
It establishes a path with AD.

In the system having such a configuration, the first
The operation when the call connection information is transmitted from the terminal device 12a accommodated in the exchange 11a to the terminal device 12b accommodated in the second exchange 11b will be described. The call connection information from the terminal device 12a is the first voice CL from the first exchange 11a.
It is transmitted to AD10a, and ATM is transmitted by the voice CLAD10a.
It is made into cells and transmitted to the ATM network 1. This cell is second
It is received by the voice CLAD 10b.

In the second voice CLAD 10b, the received cell is disassembled by the AAL1 processing unit 101 and passed to the channel selection control unit 105. The data that has passed through the channel selection control unit 105 is sent to the exchange 11b. The exchange 11b selects the accommodated terminal device 12b based on the data. This establishes the call connection.

In the above process, the call status monitoring unit 102 monitors the status of the call from the call connection information transmitted from the exchange 11b and the received call connection information, and when it is recognized that the cell is discarded, , Call state information representing the fact of cell discard, the transmission data selection unit 103 and the connection failure message generation unit 10
Notify 4. The unconnectable message generation unit 104 notified of the call status information generates a required unconnectable message. If the call state is the connection phase, the transmission data selection unit 103 sends the connection disable message to AALI.
It is sent to the processing unit 101. The AAL1 processing unit 101 converts this connection-disabled message into cells, and transfers it to the first via the ATM network 1.
Send to voice CLAD 10a.

Similarly to the above, the first voice CLAD 10a disassembles the reception cell and transfers it to the exchange 11a.
The exchange 11a or the terminal device 12a releases the call by performing the disconnection process in response to the reception of the unconnectable message. If necessary, the call connection information is sent again from the terminal device 12a to the terminal device 12b on the other side.

In the above, the voice CLADs 10a, 10
Although it is an example in the case of b, the present invention can be similarly applied to the case where information other than voice is necessarily cellized and transmitted.

[0017]

As is apparent from the above description, according to the call control method of the present invention, the connection failure information is returned to the originator when the arrival density of the call control frames exceeds the specified value as in the conventional case. Instead, when even one cell discard in the call connection information is detected, the message information is returned to the originator at that time, so that the erroneous recognition of the call connection information in the exchange due to the loss of cell units in the ATM section, that is, There is an effect that the occurrence of erroneous connection is surely prevented. In particular, it is possible to prevent erroneous recognition of call connection information due to cell discarding in the case of a terminal device having only one call control frame, which was impossible in the past.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an embodiment for realizing a call control system of the present invention.

FIG. 2 is a detailed block diagram of a voice CLAD in FIG.

FIG. 3 is an explanatory diagram of a call state according to the present embodiment.

FIG. 4 is a block configuration diagram for implementing a conventional input traffic control method.

[Explanation of symbols]

 1 ATM network (transmission line) 10a, 10b Voice CLAD (cell assembling / disassembling means) 11a, 11b Switch 12a, 12b Terminal device 101 AAL1 processing unit 102 Call state monitoring unit 103 Transmission data selection unit 104 Unconnectable message generation unit 105 Channel selection Control unit

Claims (2)

[Claims] 1. Included in the transmission data between devices provided with cell assembling / disassembling means for converting transmission data into cells and transmitting the cells to a transmission line, and disassembling cells received from the transmission line to extract the transmission data. In the method of establishing a call between the calling side device and the receiving side device based on the call connection information, the cell assembling / disassembling means included in the receiving side device is provided with a predetermined state indicating a call connectable state and a distinguishable state. A message information generation unit that generates message information and a call state monitoring unit that monitors the presence or absence of cell discard in the call connection information, and transmits the message information when the cell discard of the call connection information is detected. A call control method characterized by returning to the device on the side. 2. The call control system according to claim 1, wherein said calling side device is provided with means for releasing a call by performing a disconnection process with said transmission line upon reception of said message information.