JP2922706B2 - ISDN packet switching system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IDN in an ISDN network.
The SDN packet switching system is configured to reliably process an incoming call cancellation in particular.

[0002]

2. Description of the Related Art In packet communication in ISDN (Integrated Services Digital Network), any of a B channel (information channel) and a D channel (signal channel) can be used. Therefore, when an incoming packet requesting a call is transmitted from the calling user, the network transmits the incoming packet to the called terminal before transmitting it.
It is necessary to negotiate a channel used for packet communication with the receiving terminal.

[0003] A call setting procedure, which is a procedure for arranging a channel, is performed using a D-channel signal. After a channel is set up between the network and the called terminal, an incoming call packet is sent to the called terminal, and the packet is sent to the called terminal. Communication starts.

As shown in FIG. 10, a conventional ISDN packet compatible switching device 1 for performing packet switching includes an ISDN call processing unit 2 for controlling a call setting procedure using a D channel signal.
A packet processing unit 3 for processing packet data;
A terminal-side line control unit 5 for controlling a line to an ISDN packet terminal and a network-side line control unit 4 for controlling a line to an ISDN network are provided. The packet data is transferred between the side line control unit 4 and the ISDN call processing unit 2 and between the terminal side line control unit 5 and the ISDN call processing unit 2, and packet data is transferred between the network side line control unit 4 and the packet processing unit 3 and The data is transferred between the terminal-side line control unit 5 and the packet processing unit 3. Further, an internal signal for call setting, which is generated in the internal processing of the switching device 1, is exchanged between the ISDN call processing unit 2 and the packet processing unit 3.

[0005] The procedure until the B-channel packet communication is newly started is as shown in FIG.

Step 1: An incoming call packet (C) is sent from the ISDN network to the packet processing unit 3 through the network-side line control unit 4.
When N) arrives, Step 2; the packet processing unit 3
The ISDN call processor 2 notifies the ISDN call processor 2 of the arrival of the incoming call packet, and step 3;
, A call setup message (SETUP) is sent to the terminal via the D channel.

Step 4: The corresponding terminal responds (CO
NNECT), step 5; ISDN call processing unit 2
Notifies the packet processing unit 3 of the completion of the call setup, and confirms the response to the terminal in step 6 (CONNECT AC).
Tell K).

Step 7: The packet processing unit 3 performs link setting (SABME) with the terminal by using the B channel, and Step 8; the terminal returns a setting confirmation (UA). Thus, when packet information can be transferred by the B channel between the packet processing unit 3 and the terminal, step 9; the packet processing unit 3 transmits an incoming call packet (CN) to the terminal.

The procedure up to the start of the D-channel packet communication is as shown in FIG.

Step 1: When an incoming packet (CN) for instructing call control arrives at the packet processing unit 3 from the ISDN network via the network side line control unit 4, Step 2: the packet processing unit 3 The ISDN call processing unit 2 is notified of the incoming call, and step 3; the ISDN call processing unit 2 sends a call setup message (SETUP) to the terminal via the terminal-side line control unit 5 via the D channel.

Step 4: The terminal responds (CONNECT
T) Then, step 5; ISDN call processing unit 2 notifies completion of call setup to packet processing unit 3, and step 6; the terminal releases communication between the terminal and ISDN call processing unit 2 (RE
LEASE).

Step 7: When the release between the terminal and the ISDN call processing unit 2 is completed (REL COMP), Step 8: The packet processing unit 3 sets a link (SABME) between the terminal and the terminal using the D channel. Step 9: The terminal returns a setting confirmation (UA). In this way, when packet information can be transferred by the D channel between the packet processing unit 3 and the terminal, step 10; the packet processing unit 3 sends out an incoming call packet (CN) to the terminal.

Further, when there is an already set B channel, a new call may be transmitted on the set B channel. In such a B channel packet communication, FIG. The same call setting procedure will be taken. However, in this case, the procedure after step 8 is B
This is done using channels.

When a disconnection instruction packet for instructing cancellation of an incoming call is received in the course of the incoming call operation, an incoming call cancellation operation is performed according to a different procedure according to the reception timing of the packet as follows.

In B-channel packet communication or D-channel packet communication, as shown in FIG. 4, immediately after receiving an incoming packet (CN) from the calling side (step 1), an instruction to cancel the incoming call is issued. Disconnection instruction packet (C
If I) is received (step 4), step 5;
The packet processing unit 3 notifies the ISDN call processing unit 2 of the cancellation of the incoming call, and step 6; accordingly, the ISDN call processing unit 2 transmits a RELEASE message to the terminal, and step 7; the cancellation is completed. .

As shown in FIG. 5, if the CI is received before the CONNECT message is received from the terminal, the ISDN call processing unit 2 sends the RE to the terminal in the same manner as in FIG.
By transmitting the LEASE message, the incoming call can be canceled.

In the exchange for newly setting the B channel, as shown in FIG.
When the CI is received (Step 6) after the reception of the T message (Step 4), the ISDN call processing unit 2
Since the CONNECTACK message has already been transmitted to the terminal (step 5), a disconnection (DISK) message is transmitted to the terminal (step 9) to cancel the incoming call.

Also, B channel packet communication or D
In the channel packet communication, the incoming call procedure proceeds,
For example, as shown in FIG. 7, a data link is set between the packet processing unit 3 and the terminal (steps 8 to 8).
9), an incoming packet (C
When N) is transmitted (step 10) and the call cancellation is notified by the CI packet (step 11),
Step 12: The packet processing unit 2 transmits the CI packet to the terminal to cancel the incoming call, and
3: A packet (CF) for confirming restoration is transmitted from the terminal.

[0019]

However, the conventional ISD
In the N-packet switching system, the call setting procedure using the D-channel signal is completed in the process of receiving a packet communication using the D channel or the set B channel, but the data communication between the packet processing unit and the terminal is completed. When the link formation has not been completed yet, a CI instructing cancellation of the incoming call
When a packet is received, no operation can be performed on the terminal.

For example, in the time chart of FIG. 9, when a CI packet is received after the call setup is completed (step 5), the packet processing unit 3 has no channel with the terminal at that time. Cannot notify the terminal of the cancellation of the incoming call. When the packet processing unit 3 stops the incoming call operation according to the instruction of the CI packet,
The terminal falls into a state in which the CN packet is not transmitted although the terminal is notified of the incoming call.

Conventionally, in order to avoid such a situation, a timer is started on the terminal side by the notification of the incoming call, and the time
If you do not receive the CN packet before it goes out,
Incoming call cancellation processing is being performed. However, when such a method is employed, a longer time is required until restoration, as compared with the case where a CI packet is received at another time.

The present invention solves such a conventional problem. When a packet instructing cancellation of an incoming call is received, in any case, the terminal is notified of the cancellation of the incoming call without fail. It is another object of the present invention to provide an ISDN packet switching system capable of recovering the original state in a short time.

[0023]

Accordingly, the ISD of the present invention has been developed.
In the N-packet switching system, in response to the reception of an incoming call packet, the call setup procedure using a D-channel signal
In an ISDN packet switching system for setting a packet communication channel with a DN packet terminal, a received call packet is temporarily stored until it is transmitted to the terminal through the packet communication channel, and after the call setting procedure is completed. When the disconnection instruction packet is received, the stored incoming call packet is transmitted to the terminal, and then the disconnection instruction packet is transmitted to the terminal.

[0024]

Therefore, the call setting procedure using the D-channel signal is completed, while at the time when the formation of the data link between the packet processing unit and the terminal has not been completed, an instruction to cancel the incoming call is issued. When the received CI packet is received, a data link for transmitting the incoming packet to the terminal is formed, and after the incoming packet is transmitted to the terminal, the CI is transmitted.
A packet is transmitted to cancel the incoming call.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ISDN packet compatible switching device used in the ISDN packet switching system of the present invention is, as shown in FIG.
An incoming call packet storage unit 6 is provided for temporarily storing an incoming call packet (CN) when it is received. Other configurations are the same as the conventional configuration (FIG. 10).

The period during which the incoming call packet storage unit 6 stores the CN is a period until the packet processing unit 3 transmits the CN to the terminal. However, if the cancellation processing of the incoming call is completed before the call setting procedure using the D channel signal is completed, the CN is released.

In the ISDN packet switching system of the embodiment,
When a disconnection instruction packet for instructing cancellation of an incoming call is received after completion of the call setup procedure using the D channel signal (but before transmitting the CN to the terminal), the disconnection instruction packet is stored in the incoming call packet storage unit 6. The CN is taken out and transmitted to the terminal, and thereafter, a disconnection instruction packet is immediately transmitted to the terminal, and the incoming call cancellation processing is performed.

In the ISDN packet switching system of the embodiment,
If the disconnection instruction packet (CI) is received before the completion of the call setting procedure using the D channel signal, the incoming call is canceled according to the procedure shown in FIG.

Step 1: When the packet processing unit 3 receives an incoming call packet (CN) through the network side line control unit 4, it stores the CN in the incoming call packet storage unit 6, and Step 2: ISDN call processing unit 2 Is notified of the incoming call packet.

Step 3: The ISDN call processing unit 2 sends a call setup message (S
ETUP).

Step 4; Immediately thereafter, upon receiving a disconnection instruction packet (CI) for instructing cancellation of the incoming call, release the CN stored in the incoming call packet storage unit 6 and step 5;
The ISDN call processing unit 2 is notified of the cancellation of the incoming call.

Step 6: In response, the ISDN call processing unit 2 transmits a RELEASE message to the terminal,
Step 7: Cancellation is completed.

In a D-channel packet communication or a packet communication using a set B channel, when a CI packet is received immediately after a call setting procedure using a D-channel signal is completed, a call is received according to the procedure shown in FIG. The call is canceled.

Step 1: When the packet processing unit 2 receives an incoming call packet (CN) through the network side line control unit 4, the packet processing unit 2 stores the CN in the incoming call packet storage unit 6, and Step 2: the ISDN call processing unit 2 Is notified of the incoming call packet.

Step 3: The ISDN call processing unit 2 sends a call setup message (S
ETUP).

Step 4: The terminal responds (CONNECT
T) Then, step 5; ISDN call processing unit 2 notifies completion of call setup to packet processing unit 3, and step 6; the terminal releases communication between the terminal and ISDN call processing unit 2 (RE
(Step 8), and the release between the terminal and the ISDN call processing unit 2 is completed (REL C).
OMP).

Step 7: When a disconnection instruction packet (CI) is received between Steps 6 and 8, Step 9: A packet is transmitted to the terminal to transmit the incoming call packet stored in the incoming call packet storage unit to the terminal. A link setting (SABME) between the processing unit 3 and the terminal is performed, and step 10; upon receiving a setting confirmation (UA) from the terminal, a channel through which packet information can be transferred is formed between the packet processing unit 3 and the terminal. I do.

Step 11: When a packet information transfer channel is created, an incoming packet (C
N) to the terminal, step 12; then, transmit a CI packet to cancel the incoming call.

Step 13: The terminal transmits a packet (CF) for confirming restoration.

As described above, in the ISDN packet switching system of the embodiment, when the incoming call is canceled after receiving the CONNECT message from the terminal, the incoming packet is waited for the establishment of the data link with the terminal. Is transmitted to the terminal and then a disconnection instruction packet is transmitted to the terminal to cancel the incoming call.

As described above, by transmitting the incoming call packet and then transmitting the disconnection instruction packet, the terminal side
It is possible to return to the original state through the procedure of notifying the incoming call, receiving the incoming call packet, and receiving the disconnection instruction packet. On the other hand, if only the disconnection instruction packet is forcibly transmitted to the terminal, depending on the model of the terminal, it is not possible to return to the original state, and it is not possible to respond stably to the next call. .

[0042]

As is clear from the above description of the embodiment, in the ISDN packet switching system of the present invention, when an instruction to cancel an incoming call is issued in the course of an incoming call operation, the timing of the instruction is canceled. Regardless, it is possible to reliably perform the operation of canceling the incoming call in a short time. Also,
The operation of the terminal after the cancellation of the incoming call is stabilized, and it is possible to reliably respond to the next call.

[Brief description of the drawings]

FIG. 1 is a diagram showing a time when a CI is received after a call setup is completed in an embodiment of the ISDN packet switching system of the present invention.
chart,

FIG. 2 is a diagram showing the time when a CI is received immediately after a CN in the ISDN packet switching system of the embodiment shown in FIG. 1;
chart,

FIG. 3 is a configuration diagram showing an example of a switching device that implements the ISDN packet switching method of the embodiment shown in FIG. 1,

FIG. 4 shows a conventional ISDN packet switching system in which C
A time chart when a CI is received immediately after N,

FIG. 5 illustrates a conventional ISDN packet switching system,
Time chart when CI is received before ONNECT,

FIG. 6 shows a conventional ISDN packet switching system,
Time chart when CI is received after ONCONNECT ACK,

FIG. 7 shows a conventional ISDN packet switching system in which C
Time chart when CI is received after N transmissions,

FIG. 8 illustrates a conventional ISDN packet switching system, in which B
Time chart showing the procedure of channel packet communication,

FIG. 9 shows a conventional ISDN packet switching system in which D
Time chart showing the procedure of channel packet communication,

FIG. 10 is a configuration diagram illustrating an example of a switching device that implements a conventional ISDN packet switching method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ISDN packet compatible switching device 2 ISDN call processing unit 3 packet processing unit 4 network side line control unit 5 terminal side line control unit 6 incoming call packet storage unit

Claims (1)

(57) [Claims] In an ISDN packet switching system for setting a packet communication channel with an ISDN packet terminal in accordance with a call setup procedure using a D channel signal in response to receiving an incoming packet, the received incoming packet is transmitted by packet communication. Until transmission to the terminal through the channel, temporarily stored, when receiving a disconnection instruction packet after the completion of the call setup procedure, transmit the stored incoming call packet to the terminal, Next, the disconnection instruction packet is transmitted to the terminal.