JPH11355434A - Distributed exchange system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distributed exchange system that employs pluralities of small sized exchanges without using a coupling mechanism. SOLUTION: This system has pluralities of exchanges 10n which have pluralities of line interfaces 15 each connecting to a subscriber line and connecting to an extension link, channel switches 11 each connecting to pluralities of the line interfaces, and exchange processors 12 each controls the channel switch 11 in response to a control signal obtained via the line interfaces 15. Two optional exchanges 10n among pluralities of the exchanges 10n use the extension links to connect to each other directly. In order to directly connect the exchanges 10n, a coupling mechanism having been in use conventionally are not required. Thus, the entire cost is reduced by the cost of the coupling mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed switching system for connecting a plurality of independently operable switching devices.

[0002]

2. Description of the Related Art A conventional example of constructing a large-capacity switching system by connecting small switching devices will be described with reference to FIGS. 2 and 3 show an exchange system including a plurality of exchange devices and a coupling mechanism for connecting these exchange devices.

FIG. 2 shows a small switching device (20a, 20b, 20c) as a coupling mechanism for coupling a plurality of switching devices (10a, 10b, 10c) accommodating subscriber lines, trunk lines and the like.
Is deployed. Lines are connected so that a route can be secured from each of the small exchanges (20a, 20b, 20c) constituting the coupling mechanism to all the exchanges (10a, 10b, 10c). The small switching device is composed of a communication path switch 21a and a processor 22a. Such a system is disclosed in IEICE / Exchange Research Institute SE83-18, "Software Configuration for Large-Scale Time-Division Switching System". In this system,
Each time a call is requested, the outgoing link (the link between the originating switch and the coupling mechanism) is reduced in order to reduce the call loss in which the call cannot be set up even though the input / output line 13 is free. ) Is selected between the vacant channel and the destination link (the link between the terminating exchange and the coupling mechanism).

FIG. 3 shows a large one-stage switch 25 controlled by a processor 26 connected to a plurality of switching units (10a, 1a).
0b, 10c). In this regard, ISS92 [International Switchi
ng Symposium], A3.2 An ATMSwitching System Archite
This is disclosed in the “cture for First Generation of Broadband Services”. In this configuration, an internal link can always be selected if there is a vacancy in the input / output line 13, so that a non-blocking system in which a call loss does not occur if a channel is selected by a coupling mechanism is achieved.

[0005]

In the conventional system using the above-mentioned coupling mechanism, FIG. 2 shows the management of free / busy information of all links from the originating exchange (outgoing exchange) to the destination exchange (incoming exchange). Then, it is necessary to perform a process of finding a free channel on the incoming / outgoing link for each call. In FIG. 3, such complicated processing for each call is unnecessary, but is the same in that it is necessary to terminate control information for controlling a link and perform channel assignment processing for each call. Therefore, in the related art, the coupling mechanism, which is a common part of the system, has intelligence, and there is a problem in reliability. Further, in FIGS. 2 and 3, the cost is increased by incorporating the coupling mechanism.

An object of the present invention is to provide a distributed switching system without using a coupling mechanism.

[0007]

A plurality of line interfaces connected to a subscriber line, a plurality of line interfaces connected to an extension link, and a communication line switch connected to the plurality of line interfaces are respectively provided. A plurality of switching devices, each having a switching processor for controlling the speech path switch in response to a control signal terminated at the line interface, wherein the plurality of switching devices are optional by the extension link. A distributed switching system is provided, wherein the two switching devices are directly connected.

In a distributed switching system including a plurality of switching devices, (1) the originating switching device checks the state of the line connected to the destination switching device, and if there is an available channel,
Selecting the channel, (2) if all the lines to the destination exchange are in use, check the status of the line connected to the other exchange, and if there is a free channel, select the channel; (3) When a call arrives at the other switching device, a channel between the switching device and the destination switching device is supplemented, and the other switching device controls a communication path switch to connect the originating switching device and the destination switching device. A return path connecting the internal link channel between the originating exchange and the other exchange and the internal link channel between the other exchange and the destination exchange is set, and at the same time, the destination exchange is activated and (4) ) If all the lines between the transit exchange device and the destination exchange device are blocked, the originating and terminating exchange devices are similarly connected via a plurality of exchange devices.

[0009]

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

(1) Configuration of Switching System FIG. 1 shows a configuration of a distributed switching system according to the present invention. In the present invention, a plurality of switching devices (10a, 10b,-
-10n) to operate as one switching system. This switching system operates as one switching node (switching station). Each switching device 10 has an internal link (line between switching devices) 1 which is a line between switching devices.
4. The connection method is of a mesh type in which any two switching devices 10 (10a, 10b,..., 10n) are connected to each other by a direct line. Therefore, the internal links form a mesh network. Each switching device 10 is connected to a communication line switch 11, an input / output line 13 which is a trunk line for a subscriber line or another exchange, or an internal link 14 to terminate control information such as calling, response, and disconnection request. It is composed of a line interface 15 that performs signal processing, and an exchange processor 12 that performs processing control according to control information terminated at the line interface.
Note that the function of terminating control information such as calling, response, and disconnection request does not necessarily need to be realized by the line interface unit. Is also good. For example,
It may be a signal device for terminating a control signal in the line interface unit, or a signal device connected to the line interface unit for receiving a control signal from the line interface unit and terminating the received control signal. The switching processor 12 controls the communication path switch 1 according to the control signal.
1 to control the input / output line interfaces, or
Connect the extension link line interfaces or the input / output line interface and the extension link line interface. The exchange processor 12 includes a memory, a processing device, an I / O device for setting and reading various data with an external device (not shown), and the like. A plurality of switching devices of the present switching system each have a subscriber line and a trunk line to another switching system, which is different from the small switching devices and switches used in the conventional coupling mechanism.

The bold line in FIG.
b, the originating switching device 10a and the terminating switching device 10
2 shows a configuration diagram to which n is connected. Here, the communication path switch of the switching device 10b connects the extension link line interfaces.

(2) Exchange Processing Operation The exchange processing operation will be described with reference to FIGS. 4, 5 and 6. The operation described here is, for example, stored in a memory in the exchange processor 12 in the form of a program, and can be realized by executing this in a processing device in the exchange processor.

First, transmission processing will be described with reference to FIG.

FIG. 4 shows the operation of the calling process in the calling switching device (calling switching device). Here, the outgoing exchange device is an incoming call number for identifying a call / communication partner (destination) from the input / output line 13 (the information may be any information that can identify the partner).
This is the switching device that has received the call setting signal containing the The outgoing exchange apparatus determines the incoming exchange apparatus number from the "incoming number-incoming exchange apparatus number conversion table" of FIG. 11 based on the incoming call number indicating the communication destination in the received call setting signal (step 101). 11 is a table showing a correspondence relationship between the called number and the called exchange number of the switching apparatus accommodating the line interface related to the called number in the switching system. The switching device having the destination switching device number is connected to a destination line interface having the destination number or a line interface to a trunk line to another switching node. This table is stored in the memory of the switching processor 12. The terminating exchange device number is a number used in the exchange system (in the exchange node), and is used to identify the exchange device in the exchange system. It should be noted that the information may be any information as long as it can identify the switching device, and does not necessarily need to be a number.

Next, the originating exchange checks whether or not the own exchange is the termination exchange based on the destination exchange number, that is, determines whether or not the call is dropped by the own exchange (step 112). . In this check, each switching device stores its own switching device number in advance in the memory of the switching processor, compares the received switching device number with the previously obtained destination switching device number. It can be determined by using an exchange device. If the self-exchange device is the terminating exchange device, it activates the called subscriber from the called number (step 113). If the own switching device is not the terminating switching device, a line (internal link 1) connected to the terminating switching device.
Select 4) and check the free / busy of the multiplexed channel (time-sliced time slot or logical channel with packet multiplexing) on the internal link in the separately managed free / busy table. (Step 102). It should be noted that this free / busy table can be managed by, for example, setting that the used channel is in use each time the channel is used, and resetting the busy state each time the use is finished.

As a result of the check (step 103), if the channel to the terminating exchange is free, the channel is captured (step 104).
UT inter-station signal No. 7 is transmitted from the originating exchange to the destination exchange via the line interface 15 on the internal link side as an activation signal (step 1).
05). In this IAM message, the message is IA
It includes a message type indicating that the message is an M message, and a called number indicating the destination.

Further, the IAM message includes a method of setting the terminating exchange device number output using FIG. 11 in the area of the destination signaling point code of the IAM message and a method of not setting the same. When setting the terminating switching device number, the switching device that has received this message can use the above terminating switching device number to determine whether or not its own switching device is the terminating switching device. If not set, the called number in the message will be used. When the switching equipment number is put on the IAM message which is the activation signal, the starting exchange equipment needs to put it on the switching equipment, but the switching equipment which received the IAM message can use this switching equipment number as it is, and There is an advantage that the number conversion in the terminating exchange device is not required as compared with the case where only the number is transmitted. In particular, when the number of switching devices constituting the switching system increases, the number of transit switching devices is expected to increase,
In this case, there is a great merit that the number conversion in the terminating exchange device is not required. The terminating exchange device number is a number used in the exchange system.

On the other hand, if all the channels directly connected from the originating exchange to the terminating exchange are in use, it is checked whether the channels of the lines connected to the other exchanges are full (step 106). If there is a vacant channel (step 107), the channel to the transit exchange is captured (step 108), and an activation signal is transmitted to the transit exchange (step 109). If there is no vacancy (step 107), a search is made for a vacancy of another channel (step 110). By the above operation, even if there is no channel directly connected from the originating exchange to the destination exchange, it becomes possible to request a relay connection to another exchange.
The call blocking rate can be reduced. If all the channels are blocked, block processing is performed, that is, information of connection prohibition is transmitted to the source exchange or the subscriber without connecting (step 111).

According to the operation of FIG. 5, when there are two or more lines from the originating exchange to the terminating exchange, the route directly connecting from the originating exchange to the terminating exchange is preferentially selected as the first candidate route. As a result, efficient connection becomes possible.

Next, the incoming call processing will be described.

FIG. 5 shows incoming call processing 1. The exchange receiving the activation signal from the internal link (channel) uses the activation signal (input signal) to identify whether the received call is for its own exchange or for another exchange. Extract the destination exchange number or destination number in the destination signaling point code area of a certain IAM message (step 1)
21).

When the called number is extracted from the IAM message, the called exchange number is obtained from the called number-to-received exchange number conversion table shown in FIG. 11 and it is checked whether or not the own exchange is down (step 122). This check is performed by comparing with the switching device number held by the own switching device. If the result of the comparison is that the self-switching device has failed, the called subscriber is activated from the called number (step 128). When the switching device number is extracted from the signaling point code area of the IAM message, the switching device number is used as it is to check whether or not the own switching device has failed (step 122). The subsequent operation is the same as when the called number is extracted.

If the self-exchange device is not down, the line connected to the incoming call exchange device (destination exchange device) indicated by the incoming call number is checked for occupancy (step 123). If there is a free channel, the channel is captured (step 123). (Step 125), send an activation signal to the new terminating exchange (Step 12)
6). As described above, the switching device that performs the termination processing determines that the call received by the IAM message is a call to be relayed to the termination switching device if the destination switching device number does not match the own switching device number. Can be processed. If a channel to the switching device is found, the switching device connects the channel from the originating switching device to the switching device and the channel from the own switching device to the terminating switching device, which has been found this time, using a speech path switch. On the other hand, if all the channels are in use, block processing is performed (step 127).

FIG. 6 shows an incoming call process 2 which is another incoming call process.

The switching device that has received the activation signal from the internal link (channel) extracts the destination exchange device number or the destination number in the destination station code area in the activation signal (input signal) (step 141). When extracting the called number, the called exchange number is obtained from the called number-to-call exchange number conversion table shown in FIG. After that, the exchange device
By comparing the destination exchange number with the number of the own exchange stored in advance, it is checked whether or not the call received from the internal link is dropped by the own exchange (step 142). If the self-switching device has failed, the called party is activated from the called number (step 153).

On the other hand, if the self-switching device is not down, the line connected to the receiving switching device indicated by the called number is checked for occupancy (step 143). If there is a free channel to the receiving switching device, the channel is captured. (Step 14
5), sending an activation signal to the terminating exchange (step 1)
46). If all channels to the terminating exchange are in use, select a channel to another exchange. In the selection of another switching device, a switching device that has never passed through is selected from the number of the pass-through switching device included in the activation signal. This prevents unnecessary ping-pong transfer of calls between the two switching devices. Specifically, for example, this can be realized by the switching device that has issued the activation signal inserts the own switching device number into the activation signal and uses it as the pass-through switching device number. Also, 2
An exchange system having one or more intermediate routes can be configured. It checks whether the channel of the line connected to the selected switching equipment is full (steps 147, 1).
48). If there is room, capture the channel (step 1
49), and transmits a start signal to the transit exchange (step 150). If there is no vacancy, a search is made for a vacancy of another line (step 151). If all the lines are blocked, block processing is performed (step 152).

As described above, the present switching system has a function of finding a line to a target switching device via another switching device when a direct line (channel) to the target switching device is blocked. Therefore, the blocking rate is smaller than in the case where the direct line is blocked when the line is blocked.

(3) Connection of speech path FIGS. 7 to 9 show an exchange system composed of four exchanges, and the connection in this figure indicates the connection state of the speech path between the originating and terminating exchanges. Show. Note that, for simplification of the drawing, individual internal links connecting between the switching devices are not shown. Here, switching device 201 is a calling switching device that accepts a call from a calling subscriber or another switching system. The switching device 204 is a terminating subscriber receiving the call or a terminating switching device having a trunk line to another switching system. 7 shows a case where an internal link is directly connected from the originating exchange to the destination exchange. FIG. 8 shows one transit exchange (202), and FIG. 9 shows a transit exchange (2).
02, 203) are connected. Here, in FIG. 9, for example, the relay switching unit 203 does not send an activation signal to the originating switching unit so that the function of the incoming call processing 2 (particularly, to the switching unit that has passed so far using the passing switching unit number). It is necessary to stop issuing the start signal again). In the case of FIG. 7 and FIG. 8, a call can be set to the terminating exchange device using the terminating process 1, but a call path can be set even if the terminating process 2 is implemented. However, the state of the channel between the switching devices is constantly changing, that is, the connection from the originating switching device to the receiving switching device cannot always be directly connected by a link or a single relay. It is desirable to have.

[0029]

According to the configuration of the present embodiment, a mesh connection is used in which two switching devices are connected by a direct line.
The coupling mechanism used conventionally is not required. Therefore, the overall cost is reduced by the cost of the coupling mechanism.

Next, a comparison will be made between the cost of the present system and that of the conventional switching system (FIGS. 2 and 3). For comparison, the system capacity is 64k lines, the capacity of one switching device is 16k lines,
The switch in the coupling mechanism shown in FIG.
It is assumed that the same unit as in (k lines) is used, the cost is proportional to the number of lines, and the line number proportional part is 70% of the entire switching system (30% is a common part).

Based on the above assumptions, an evaluation is performed as follows.

· Method of the present application: 16k lines (switching device) × 4 · Figure 2 method: 16k lines (switching device) × 4 + 16k lines (coupling device) × 2 · Figure 3 method: 16k lines (switching device) × 4 + 64k lines ( As described above, assuming that the present system is 1 for the line proportional unit, the cost is 1.5 in the system of FIG. 2 and 2 in the system of FIG. Therefore, in consideration of the common part, the present system can reduce the cost by 26% compared to the system in FIG. 2 and 41% compared to the system in FIG.

Therefore, when constructing a large-capacity switching system by connecting small exchanges (corresponding to an exchange in this embodiment), the cost is lower than that using a coupling mechanism that cannot accommodate subscriber lines. It can be realized effectively.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a switching system to which the present invention is applied.

FIG. 2 is a configuration diagram of an exchange system using a small-capacity switch as a coupling device.

FIG. 3 is a configuration diagram of an exchange system using a large-capacity single-stage switch as a coupling device.

FIG. 4 is a flowchart showing an outgoing call process in the outgoing exchange device.

FIG. 5 is a flowchart showing an incoming call processing 1 in the relay exchange device or the incoming call exchange device.

FIG. 6 is a flowchart showing an incoming call process 2 in the relay exchange device or the incoming call exchange device.

FIG. 7 is a diagram showing a case where an exchange device is directly connected.

FIG. 8 is a diagram showing a case where an incoming / outgoing exchange device is connected via one relay exchange device.

FIG. 9 is a diagram showing a case where an incoming / outgoing exchange device is connected via two relay exchange devices.

FIG. 10 shows an ITU-T No. The figure which shows the IAM message of a 7 signal system.

FIG. 11 is a view showing a called number-calling exchange device number conversion table.

[Explanation of symbols]

10 ... exchange device, 11 ... switch, 12 ... processor,
13: input line, 14: line between switching devices, 15: line interface, 20, 25: coupling device, 21: switch, 22, 26 ... processor, 101-111 ... outgoing process, 121-128 ... incoming process 1, 141 153: incoming call processing 2, 201 to 204: exchange device, 205, 21
5, 216, 225, 226, 227...

Claims (13)

[Claims] 1. A plurality of line interfaces connected to a subscriber line, a plurality of line interfaces connected to an extension link, a communication line switch connected to the plurality of line interfaces, respectively, A plurality of switching devices having a switching processor for controlling the speech path switch in response to a control signal obtained via A distributed switching system, wherein two said switching devices are directly connected. 2. The first means for connecting the call using the extension link which directly connects the originating switching apparatus that has accepted the call and the terminating switching apparatus that receives the call, the outgoing switching apparatus, Incoming switching device, and further using another switching device, using the extension link between the outgoing switching device and the other switching device, and using the extension link between the other switching device and the receiving switching device 2. The distributed switching system according to claim 1, further comprising second means for connecting said call. 3. The distributed switching system according to claim 2, wherein said first means is used prior to said second means. 4. A terminating switching device that stores identification information for identifying a switching device in each of a plurality of switching devices and terminates the call using the identification information in a start signal of an extension link between the switching devices. The distributed switching system according to claim 1, wherein the system is specified. 5. A switching device having a communication path switch, a signal device for terminating a control signal, a line interface, and a call processing processor for performing call processing control, wherein any two switching devices are directly connected. In a distributed switching system having a mesh type network, an originating switching device (hereinafter referred to as an originating switching device)
Means for using a line that directly connects the outgoing exchange apparatus and the incoming exchange apparatus when connecting a call path to an exchange apparatus on the receiving side (hereinafter referred to as an incoming exchange apparatus); Uses a line connecting one switching subscriber and a switching device to which no trunk is connected (hereinafter referred to as a transit switching device) and a line connecting the transit switching device and the receiving switching device. A distributed switching system having means. 6. A distributed network comprising a plurality of switching units having a call path switch, a line interface, and a call processor for performing call processing control, and a mesh network to which any two switching units are directly connected. In a switching system, when a communication path is connected from an outgoing exchange to an incoming exchange, there are means for using a line directly connecting the outgoing exchange and the incoming exchange, and a plurality of lines between the outgoing exchange and the incoming exchange. Means for connecting a communication path via a transit switching device, i.e., a line connecting an outgoing switching device and one transit switching device, a line connecting between transit switching devices, one transit switching device and an incoming call switch A distributed switching system having means for using a line connecting devices. 7. A distributed network comprising a plurality of switching units having a call path switch, a line interface, and a call processor for performing call processing control, and a mesh type network to which any two switching units are directly connected. In a switching system, a distributed switching system in which a first priority is given to selection of a line that directly connects an outgoing switching device and an incoming switching device in an outgoing switching device. 8. A mesh network in which a communication path switch, a line interface, a plurality of switching devices having a call processor for performing call processing control, and any two switching devices are directly connected. In the case where there is no vacancy in the line directly connecting the originating exchange device and the destination exchange device, the originating exchange device selects the vacant first line connected to the transit exchange device, A distributed switching system in which the transit switching device selects a second line connected to the destination switching device and connects the first line and the second line in a switch in the transit switching device. 9. A mesh network in which a plurality of switching devices having a call path switch, a line interface, a call processor for performing call processing control, and any two switching devices are directly connected. In the case where there is no vacancy in the line directly connecting the originating exchange device and the destination exchange device, the originating exchange device selects the vacant first line connected to any first exchange device. Next, when the first transit exchange device selects a line connected to the destination exchange device, if the first transit exchange device detects that all the lines are closed, there is a free space connected to the second transit exchange device. A distributed switching system for selecting a second line and connecting the first line and the second line in a switch of the first transit switching device. 10. The selected transit switching device selects a line connected to the destination switching device if there is a vacancy, and if there is no vacancy, selects a line connected to the transit switching device that has never passed. The distributed switching system according to claim 8. 11. A mesh network in which a communication path switch, a line interface, a plurality of switching devices having a call processor for performing call processing control, and any two switching devices are directly connected. In the case where there is no vacancy in the line directly connecting the originating exchange device and the destination exchange device, the originating exchange device selects the vacant first line connected to the transit exchange device, A distributed switching system in which a call is lost when all of the second lines connecting the transit switching device to the destination switching device are in use. 12. A switching device having a call path switch, a line interface, a call processor for performing call processing control, a mesh network to which any two switching devices are directly connected, and an activation signal. Means for converting from the called number information to the called exchange number when receiving from the line interface connecting the subscriber or the trunk, and transmitting an activation signal including the called exchange number to the other exchange; and from the other exchange. A distributed switching system having means for performing an incoming call process according to the incoming call switching device number when receiving an activation signal. 13. A switching device having a call path switch, a line interface, a call processor for performing call processing control, a mesh network to which any two switching devices are directly connected, and an activation signal. Means for transmitting a start signal including the called number to another switching device when received from a line interface connecting a subscriber or a trunk; and receiving a start signal from the other switching device when receiving a start signal from another switching device. A distributed switching system having means for performing incoming call processing by number.