JPH06169318A - Call processing system for atm switchboard - Google Patents

Abstract

PURPOSE:To suppress the increase of the number of states due to the increase of the number of connections and at the same time to make all connections select the same route (VPI). CONSTITUTION:A task starting part 31 receives the signals (call and connection control signals) from a signal control part 21 for generation of a call and generates a call control task 32a in response to the call to start the task. At the same time, the part 31 generates the connection control tasks 33a1-33am in response to the connections and starts these tasks. The task 32a performs the call control processing for the control of an entire call, like the charging control, the selection control of the same route for each connection, etc., based on the originating number and called number included in the call control signal. Meanwhile each of tasks 33a1-33am sets up and releases the path of each connection by the instruction of the task 32a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a plurality of connections (voice connection, video connection, data connection, etc.) by one call when realizing a connection service using a multimedia terminal connected to an ATM exchange. Regarding call processing method. There is an increasing need for multimedia communication including not only voice communication and data communication but also moving image communication. As a means for realizing such broadband communication, an asynchronous transfer mode (Asynchronous T
B-ISDN (Br) based on ransfer mode (ATM)
Oddband-ISDN) switching technology has been agreed in CCITT, and it is being specified to separate signals for call processing and signals for connection processing. The ATM switch is capable of communicating a wide variety of media. Therefore, in order to effectively use a multimedia terminal such as a videophone on the switch, it is necessary to control multiple connections with one call. There is.

[0002]

2. Description of the Related Art In conventional STM networks, the types of lines that can be handled are limited, so the types of media that can be communicated are limited, and signals are not separated into calls and connections. For this reason, conventionally, there has been no sufficient study on multi-connection control in consideration of separation of call and connection.

[0003]

With the introduction of the ATM switch, there is an increasing demand for simultaneous communication of a plurality of media at the time of call setup using a multimedia terminal and a request for adding a new media communication at the time of communication. It is thought that. Also, CCITT is defining the separation of signals into calls and connections. For this reason, it is necessary to establish a call control system in the ATM exchange in consideration of separation of call and connection.

In view of the above, an object of the present invention is to provide a call processing system in an ATM exchange in consideration of separation of call and connection. Another object of the present invention is to separate the call control processing for controlling the entire call from the control processing for each connection, thereby suppressing an increase in the number of states due to an increase in the number of connections and reducing the complexity of the call processing. It is to provide a call processing system in an ATM exchange. Still another object of the present invention is to allow all connections to select the same route (VPI), thereby making it possible at the destination station to judge that the processing separated by the originating station is the same call. It is to provide a call processing system in an ATM exchange that enables control.

[0005]

FIG. 1 is a diagram for explaining the principle of the present invention. Reference numeral 21 is a signal control unit for receiving a signal from a subscriber or another exchange, 31 is a task activation unit provided in one exchange, 32a is a call control task that is activated for a call and controls the entire call, 33a ₁ ~ 33am is for call handling, and
It is a connection control task generated for each connection.

[0006]

When the task activation unit 31 receives the signal for generating a call (call control signal and connection control signal) from the signal control unit 21, the task activation unit 31 generates and activates the call control task 32a corresponding to the call, and also activates the connection. start to generate a connection control task 33a ₁ ~33am. The call control task 32a performs call control processing for controlling the entire call, such as charging control and control for selecting the same route for each connection, based on the calling number and the called number included in the call control signal, and each connection control task 33a. _{1 to} 33am control the establishment and release of the path of each connection according to the instruction from the call control task. Since the call control processing and each connection control processing are separated in this way, even if the number of connections to be processed by one call increases, it is possible to suppress an increase in the number of states of the entire call, and call processing control is easy. become.

[0007] In addition, the call control task 32a is to be selected by the respective connection control task 33a ₁ ~33a ₂ specify the same route (VPI). By doing so, it becomes possible for the destination to judge that each connection is the same call. Furthermore, each connection control task sets the path based on the route specified by the call control task, and notifies the call control task of the result, and the call control task notifies the connection that the path cannot be set for the specified route. If a control task exists, a different route is specified for each connection control task and selected. If this is done, the possibility of call loss can be suppressed, and if the call control task cannot set the path for all routes, it is regarded as a call loss and a signal to that effect is sent by the sender. Can be sent back to.

[0008]

【Example】

(a) Outline of ATM network In the ATM system, multiple logical links are set up on a physical line to allocate the line to a plurality of calls. Then, moving image data, voice data, and the like from the terminal corresponding to each call are decomposed into fixed-length information units (called cells) and sequentially sent to the line to realize multiplexing. The cell is 53 as shown in FIG.
It is composed of a fixed length block of bytes, of which 5 bytes are a header part HD and 48 bytes are an information field (information part) DT. The header part HD has a virtual channel number (Virtual Channel Identifie) for call identification so that the destination can be known even after the data is decomposed into blocks.
r: VCI) is included, and a virtual path identifier (VPI) that specifies a route is also included,
A generic flow control GFC (Generic Flow Control) used for flow control between links, a payload PT (Payload Type), a header error correction code HEC (Header Error Control), and the like are included.

FIG. 3 is an ATM for explaining the ATM system.
It is a schematic block diagram of a network, 11a and 11b are terminal devices, 1
3 is an ATM network. The ATM network 13 includes an information network 13a for transmitting data cells and a signal network 13b for transmitting control signals.
And each ATM switch 13c-1 in the information network 13a.
CPUs 13d-1 to 4d-n of 13c to 13c-n are connected to the signal network 13b. When the calling terminal 11a performs a calling operation to call the called terminal 11b, the cell assembling unit in the calling terminal divides the data including the calling number, the called number, the type of the terminal, and the attribute into cell units, and divides the data into cells. The signal VCI (predetermined for each terminal) is attached to the data to generate a signal cell,
The signal cell is sent to the ATM network 13.

When the signaling device (not shown) of the ATM exchange (transmission side exchange) 13c-1 receives a signal cell, it assembles the information contained in the signal cell and notifies the CPU 13d-1. The CPU performs call processing such as caller service analysis processing, billing processing, callee digit translation processing, and the like.
I) and call identification information (VCI) are determined, and the signaling network 13b
Via NO. According to the No. 7 protocol, connection information including a calling number, a called number, VPI, VCI and other data is sent to the next transit exchange. After that, the transit exchange performs the same process, and finally the ATM exchange (incoming exchange) 13c- to which the incoming terminal is connected from the outgoing exchange 13c-1.
Paths up to n and relay ATM switches 13c-2, 13c-3, ...
Is determined. Upon receiving the connection information including the calling number, the called number, and the VCI of the upper ATM switch, the called exchange 13c-n assigns a predetermined VCI to the called terminal and checks whether the called terminal 11b can talk. If the call is possible, the signaling network 13b indicates that the call can be made.
c-1 is notified and the originating exchange allocates a predetermined VCI to the originating terminal 11a.

Each ATM switch 13c-1 to 13c-n on the path
Corresponds to the VCI of the upper ATM switch for each path,
(1) Output path (output highway) of the cell having the VCI
And (2) register new VCI and VPI to be added to the output cell in the built-in routing table. From the above, the sending terminal 11a and the receiving terminal 1
When a path is formed between 1b, both terminals send and receive a calling cell and a responding cell to confirm the communication procedure. Thereafter, the transmitting terminal 11a decomposes the data to be transmitted into a predetermined byte length, attaches a header containing the assigned VCI to generate a cell, and sends the cell to the ATM network 13. When each ATM switch 13c-1 to 13c-n receives a cell from a host switch via a predetermined input highway,
VC of the input cell based on the routing table
Change I and send it to the designated exit highway.
As a result, the cell output from the calling terminal 11a reaches the terminating side exchange 13c-n via the path determined by the call control. Based on the routing table, the terminating exchange 13c-n replaces the VCI added to the input cell with the VCI assigned to the terminating terminal, and then the terminating terminal 11b.
To the line to which is connected.

Thereafter, the calling terminal 11a sequentially sends cells to the called terminal 11b, and the called terminal assembles the information section DT included in the received cell to restore the original data. The above is 1
For one call, by changing the VCI values held at both ends of each line between the terminal-ATM switch and the adjacent ATM switch, it is possible to set up a logical link corresponding to many calls on one line. Therefore, high-speed multiplex communication can be realized. According to the ATM method, since information of information sources having different transmission speeds such as moving images, data, and voice can be multiplexed, one transmission line can be effectively used, and packet exchange can be performed by software. There is no need for retransmission control and complicated communication procedures as described above, and ultra-high-speed data transmission of 150 Mbps is possible.

(B) Embodiment of the present invention FIG. 4 is a block diagram of an embodiment of the present invention. The overall configurations 1 and 2 are multimedia terminals, for example, videophones 10 and 50 are ATM exchanges. No ATM switch is shown in each of the ATM exchanges 10 and 50, and only the CPU is shown. In the ATM switch 10, 20 is an OS
(Operating system), 30 is an application unit. In the operating system 20,
Reference numeral 21 is a signal control unit (DSS) that receives a signal from the multimedia terminal 1, and 22 is activated by a system call from the application unit, and is there a vacant band specified by the VPI specified by the call admission control algorithm? The communication path control unit (SWC) 23 for judging and notifying is a signal control unit (ISU) for exchanging signals with other exchanges.
P).

In the application section 30, 31 is a task starting section, 32a is a call control task, 33a ₁ is a voice connection control task, and 33a ₂ is a moving picture connection control task. One task activation unit 31 is provided in the exchange and receives a signal for generating a call to activate a call control task 32a corresponding to a call and connection control tasks 33a ₁ and 33a ₂ corresponding to a connection. Call control task 3
2a is activated by the task activation unit 31, and the signal control unit 2
Signals are exchanged between 1 and 23 to control the entire call such as billing control and the same route selection control for each connection. The connection control tasks 33a ₁ and 33a ₂ are activated by the task activation unit 31 for each call and for each connection, and reserve the path (VCI) in the route (VPI) designated by the call control task 32a. Perform capture and release processing.

In the ATM switch 50, 60 is an OS
(Operating system), 70 is an application unit. In the operating system 60,
Reference numeral 61 is a signal control unit (DSS) for receiving a signal from the multimedia terminal 2, 62 is a communication path control unit (SWC), 6
3 is a signal control unit (I
SUP). 7 in the application unit 70
Reference numeral 1 is a task activation unit, 72a is a call control task, 73a ₁ is a voice connection control task, and 73a ₂ is a moving picture connection control task.

Overall Operation In the case of making a videophone call from the multimedia terminal 1 accommodated in the ATM exchange 10 to the multimedia terminal 2 accommodated in another exchange 50, in other words, the connection of voice and moving images is established. The case of connecting simultaneously at the time of call setup will be described. 5, 6 and 7 are sequence flow diagrams for realizing the videophone service.

(A) When the videophone key is pressed from the multimedia terminal 1 and the telephone number of the other party is input, the terminal 1 sends out a C-SETUP message (call control signal: including outgoing and incoming numbers). At the same time, the B-SETUP message (connection control required signal: including band (transmission rate), peak value, burst property, etc.) is sent to the exchange 10 for each audio connection and moving image connection. Since these messages are call setting and connection setting messages, the signal control unit 21 of the exchange 10 sends them to the task starting unit 31. (b) The task activation unit 31 uses the call control task 32a for the terminal 1 and the connection control task 3 for each of the voice and the moving image based on the message sent from the signal control unit.
3a _{1 to} 33a ₂ are generated, and C-SETUP and B-SETUP are generated for each.
To start it.

(C) Each connection control task 33a _1-
33a ₂ notifies the call control task 32a of the band information included in the received B-SETUP message by the B-REQ message. Upon receiving the call control task 32a is notified of the band from the connection control task 33a ₁ ~33a _2, a plurality of routes to (VPI) calculated to the called terminal, each one VPI of which the B-SEL signal It is specified in the connection control tasks 33a _{1 to} 33a ₂ . Each of the connection control tasks 33a _{1 to} 33a ₂ checks whether or not there is a margin for transmitting voice and moving image in the designated VPI band,
If there is room, reserve (reserve) a given VCI for the VPI and audio / video connection, and to that effect B-
The RES signal notifies the call control task 32a. As described above, the same route (VPI) and VCI for each connection are reserved for each connection of voice and moving image. Detailed processing for reserving the same VPI will be described later with reference to FIG.

(D) When the reservation of the same VPI is completed, the call control task 32a receives the reserved V via the signal controller 23.
The C + B-SETUP message is sent to the ATM exchange (the exchange 50 that accommodates the terminal 2 in FIG. 4) to which the PI is connected. The signal control unit 63 of the exchange 50 sends these signals to the task activation unit 71 because these signals are call setting and connection setting signals. (e) Based on the signal sent from the signal control unit, the task activation unit 71 uses the call control task 72a for the terminal 2 and the connection control tasks 73a _1-
73a ₂ is generated, and C-SETUP message and B-SET are generated for each.
Pass UP message and start.

(F) Each connection control task 73a _1-
73a ₂ notifies the call control task 72a of the band information included in the received B-SETUP message by the B-REQ signal. Call control task 72a each connection control task 73a ₁ ~
Upon receiving the notification of bandwidth from 73a _2, obtains the route to the called terminal (VPI), specified for each connection control task 73a ₁ ~73a ₂ the VPI by B-SEL message. If there is a margin for transmitting voice and video in the designated VPI band, a predetermined VCI for the VPI and voice and video connection is reserved (reserved), and the completion of reservation is indicated by the B-RES signal. Notify the call control task 72a. As described above, the same route (VPI) is reserved for each connection of voice and moving image. (g) When the reservation is completed, the call control task 72a sends a C-SETUP message to the terminal 2 via the signal controller 61.

(H) Also, the call control task 72a is
Video connection control task 73a ₁~ 73a₂To all connections
The B-SUC message indicates that the
The connection control task notified is signaled.
Send a B-SETUP message to terminal 2 via control unit 61
It (i) Terminal 2 receives the C-SETUP and B-SETUP messages.
ALT message indicating that response is possible
Is sent to the call control task 72a via the signal control unit 61.
It The call control task 72a receives the signal control units 63 and 23.
And sends an ALT message to the call control task 32a. This
As a result, the call control task 32a receives the ALT message.
It is sent to the terminal 1 via the number control unit 21.

(J) After sending the ALT message, the terminal 2 sends the C-CONN and B-CONN messages via the signal control unit 61 when the callee goes off-hook, respectively, and the call control task 72a and the connection control tasks 73a ₁ and 73a _{2 respectively.} Send to. Each of the connection control tasks 73a ₁ and 73a ₂ captures the previously reserved VPI and VCI and sets a connection, and then sends a B-EST message to the call control task 72a. (k) Accordingly, the call control task 72a sends the C + B-CONN message to the call control task 3 via the signal control units 63 and 23.
2a. (m) The call control task 32a sends the C-CONN message to the terminal 1 via the signal control unit 21, and then sends the B-CONN message to each of the connection control tasks 33a ₁ and 33a ₂ .

(N) Each connection control task 33a ₁ ,
33a ₂ captures the previously reserved VPI and VCI,
After setting the connection, the B-CONN message is sent to the terminal 1 via the signal control unit 21. As described above, a multi-connection for voice and moving images is established between the terminal 1 and the terminal 2, and the videophone is in communication. (o) When communication is completed and the terminal 1 is disconnected, the terminal 1
The C-REL and B-REL messages are sent via the signal control unit 2 to the call control task 32a and the connection control tasks 3 respectively.
It is sent to 3a ₁ and 33a ₂ .

(P) Each connection control task 33a ₁ ,
After releasing the VPI and VCI being captured, 33a ₂ sends a B-DEL message to the call control task 32a and terminates its own task. (q) Upon receipt of the B-DEL message, the call control task 32
a sends the C + B-REL message to the call control task 72a via the signal control units 23 and 63. (r) The call control task 72a sends a C-REL message to the terminal 2 via the signal control unit 61, and then sends a B-REL message to each of the connection control tasks 73a ₁ and 73a ₂ .

(S) Each connection control task 73a ₁ ,
After releasing the VPI and VCI being captured, 73a ₂ sends a B-DEL message to the call control task 72a, and then sends a B-REL message to the terminal 2 via the signal control unit 61. End the task. (t) As a result, the terminal 2 sends out a C-RELCOM message. (u) The call control task 72a sends a C-RLC message to the call control task 32a via the signal control units 63 and 23, and then terminates its own task.
Receive the message and terminate the invoking task.

Reservation control for the same route (VPI) FIG. 8 shows a call control task 32a for reserving the same VPI for all connections when multi-connection is set up.
5 is a flowchart of the processing of FIG. Upon receiving the B-REQ message from each of the connection control tasks 33a ₁ and 33a ₂ , the call control task 32a reads the bandwidth (transmission rate) of voice and moving image from the message (step 101). For example, each connection control task 33a ₁ , 33a ₂ is a B-RE.
64Kbps for voice and 20M for video by Q message
Send the required bandwidth of bps. Then, the call control task 32a is C
-A list of all routes (VPI list) that can reach the partner terminal is created from the called number included in the SETUP message (step 102).

After that, it is checked whether or not the VPI exists in the VPI list (step 103), and if it exists, the top VPI (set as VPII) is selected (step 10).
4). Then, by the B-SEL message, the first VPI (V
PII) to each of the connection control tasks 33a _{1 to} 33a ₂
To perform VCI reservation processing. Upon receipt of the B-SEL message, each of the connection control tasks 33a _{1 to} 33a ₂ gives the call path control unit 22 of the operating system 20 a margin for transmitting the voice and the moving image in the designated VPI band. Ask to look up. The call path control unit 33 checks whether there is a margin according to the call admission control algorithm and notifies the result to each connection control task.

[0028] Each connection control task 33a ₁ ~33
a ₂ is the VPI and a predetermined V if there is a margin for transmitting the voice and the moving image in the designated VPI band.
The CI is reserved (reserved), and the completion of the reservation is notified to the call control task 32a by a B-RES message. If the reservation cannot be made, the fact is notified to the call control task 32a by a B-NOT message (step 105). The call control task 32a is
If the reservation is completed, and B-RES messages are received from all the connection control tasks 33a ₁ and 33a ₂ , it is determined that the reservation of the same VPI has succeeded for all the connections and the processing is terminated (step 10).
6).

However, if the reservation is not possible in all the connection control tasks 33a ₁ and 33a ₂ , the control task 32a sends a B-CAN message to release all the reserved VCIs and to make the VPI list. The first VCI is deleted from (step 107), and then step 1
The processing from 03 is repeated. After that, the processing is repeated until the reservation of the same VPI succeeds, and before the reservation succeeds, the VP
If the I list becomes empty, that is, if all the VPIs obtained in step 102 cannot be reserved, it is regarded as a call loss, and a C-REJECT message indicating that is sent to the multimedia terminal 1 which is the transmission source. Although the present invention has been described above with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention described in the claims, and the present invention does not exclude these.

[0030]

As described above, according to the present invention, since the call control processing and each connection control processing are separated, even if the number of connections to be processed by one call increases, the increase in the number of states of the entire call can be suppressed. The call processing can be easily controlled.
Further, according to the present invention, since the same route (the same exchange) is selected for all the connections, it is possible to judge that each connection is the same call at the destination station, and the multi-connection control is performed. It will be possible. Furthermore,
According to the present invention, each connection control processing unit (connection control task) performs path setting based on the route specified by the call control processing unit (call control task), and notifies the call control processing unit of the result. , If the call control processor has a connection for which path setting is not possible for the specified route, it is configured to specify a different route to each connection control processor and select it. In addition, the call control processing unit can consider that it is a call loss and can send back a signal to that effect to the transmission source when path setting is not possible for all routes.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram of an ATM cell.

FIG. 3 is an explanatory diagram of an ATM network.

FIG. 4 is a configuration diagram of an embodiment of the present invention.

FIG. 5 is a sequence flow diagram (part 1) for realizing a videophone service.

FIG. 6 is a sequence flow diagram (part 2) for realizing a videophone service.

FIG. 7 is a sequence flow diagram (part 3) for realizing a videophone service.

FIG. 8 is a flowchart of a process for reserving the same route for all connections.

[Explanation of symbols]

21 ... signal controller 31 ... task start portion 32a ... call control task 33a ₁ ~33am ·· connection control task

Claims (6)

[Claims] 1. In a call processing system of an ATM switch for controlling a plurality of media connections by a single call from a multimedia terminal connected to an ATM switch in an asynchronous transfer mode, call control processing means for controlling the entire call. A call processing system in an ATM exchange characterized in that connection control processing means for controlling establishment and release of a path of each connection are separately provided, and call control and connection control processing are separated. 2. A task activation unit is provided in the exchange, and the task activation unit generates a call control task as a call control processing unit and a connection control task as each connection control processing unit in response to a call when a call is generated. The AT according to claim 1, wherein the call is accepted by being activated.
Call processing method in M switchboard. 3. The call processing method in an ATM switch according to claim 2, wherein the call control task causes each connection control task to specify and select a path (VPI) of the same route. 4. The ATM switch according to claim 3, wherein each connection control task sets and releases a path based on a route designated by the call control task and notifies the call control task of the result. Call processing method in. 5. If there is a connection control task for which path setting is not possible for the route for which the call control task is designated, the call control task designates another route for each connection control task and causes the connection control task to select the route. A call processing system in an ATM exchange according to claim 4, wherein 6. The ATM according to claim 5, wherein the call control task considers that a call is lost and sends back a signal to that effect to the transmission source when path setting is not possible for all routes. Call processing method in exchange.