JPH05160851A - Electronic exchange method for asynchronous transfer mode communication system - Google Patents

Abstract

PURPOSE:To improve the operating efficiency of a relay line while ensuring the communication quality without interruption of a call in the congestion state of the relay line in the ATM communication system. CONSTITUTION:An ATM electronic exchange 10 consists of a cross connect device 30 used to provide a communication path being plural virtual paths to a relay line 400 and with an exchange device 20 used to connect a terminal equipment and the virtual path or between the virtual paths for each call. A call processing section 96 of the exchange device 20 selects a virtual path to be connected in response to a medium of the communication information and the attribute of the terminal equipment. A cross connect processing section 97 of the cross connect device 30 selects the virtual path without interrupting a call in response to the bypass priority and a bypass destination decided in advance for each virtual path at the congestion of the relay line.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electronic switching system of an asynchronous transfer mode (ATM) communication system, and more particularly to a control system when a trunk line is congested in an ATM communication system.

[0002]

2. Description of the Related Art In the ATM communication system, when a terminal makes a call or responds, the terminal is first connected to a maximum cell rate and an average cell rate (ATM throughput) transmitted per unit time and a trunk line. By using the ATM throughput of all the terminals, the band of the trunk line corresponding to the ATM throughput is secured according to a known predetermined band allocation method to connect the call.

Then, the required quality (cell delay time, cell loss rate) is determined according to the attribute of the terminal and the medium of the communication information, and there is a delay for each cell for putting the communication information according to the required quality. Quality control is performed by preferentially passing cells or discarding cells with low required quality.

In the conventional ATM communication system, since the quality control as described above is performed, even if the call has the same required quality, the quality will be different due to the difference in the usage rate of the transit line passing through. This means that the call of the lowest quality must satisfy the required quality, and there is a drawback that the use efficiency of the network (relay line) is reduced.

Further, when the terminal transmits data at a higher speed than the ATM throughput declared when allocating the band, or even within the declared ATM throughput,
When high-speed data transmissions from multiple terminals occur simultaneously, the trunk becomes abnormally congested. There is also a drawback that the required quality (cell delay time, cell loss rate) of a call that encounters this abnormal congestion cannot be secured.

[0006]

It is an object of the present invention to use the concept of a virtual path for bundling traffic and perform switching control for each virtual path without disconnecting a call when a trunk line is congested, so that another free relay can be used. An ATM designed to secure communication quality and improve network usage efficiency by diverting calls to the line
It is to provide a communication type electronic exchange system.

[0007]

According to the present invention, there is provided an electronic exchange system for accommodating a relay line and a terminal of an asynchronous transfer mode communication system having a plurality of virtual paths whose paths and capacities are logically predetermined and set. Therefore, when connecting between the terminal and the relay line or between the relay lines, the communication quality is determined according to the attribute of the terminal and the medium of communication information, and the virtual path 1 is determined according to the communication quality. Virtual path selection means for selecting one, a means for predefining a detour priority and a detour destination virtual path for each virtual path, a congestion detection means for detecting congestion of the trunk line, and the congestion detection means In response to detection of congestion by the virtual path switching means for switching the virtual path by determining a bypass virtual path based on the priority of the bypass for each virtual path and the virtual path of the bypass destination. Asynchronous transfer mode Electronic switching system of the signal system is obtained.

[0008]

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

FIG. 1 is a block diagram showing an ATM exchange according to an embodiment of the present invention. In this example, the ATM electronic exchange 1
0 accommodates the terminal 100 and the ATM communication trunk 400, but it goes without saying that there is also an ATM electronic exchange (see 10C in FIG. 5) housing the trunks.

This electronic exchange 10 basically has an exchange mechanism 2
0 and the cross-connect mechanism 30. Exchange mechanism 20
Is a call connection process for the terminal 100, and the cross-connect mechanism 30 is a connection process for the trunk line 400.

The electronic exchange 10 accommodates the terminal 100 in the trunk line interface and the ATM type trunk line 400 in the trunk line interface 82. The cross-connect processing unit 97 in the cross-connect mechanism 30 activates the virtual path switch control unit 93 of the switch control unit 91, and in response thereto, the virtual path switch control unit 93 controls the connection of the virtual path switch 86 of the ATM switch 84. By doing so, a communication path called a virtual path is set between the relay line interface 82 and the virtual path interface 83.

The signal processing unit 94 in the exchange mechanism 20 performs signal processing (generally called a protocol, which is a procedure for transmitting and receiving information) necessary for call setup with the terminal 100. The signal processing unit 95 performs signal processing (protocol) necessary for call setting with another electronic exchange opposite to it via the virtual path set on the trunk line 400, and receives from the terminal or the opposite electronic exchange. Translate the request information,
The call processing unit 96 is notified, or the instruction information from the call processing unit 96 is translated and sent to the terminal or the opposing electronic exchange.

In response to the call request from the terminal 100, the call processing unit 96 determines the communication quality (cell delay time, cell discard rate) according to the attribute of the terminal 100 and the medium of communication information, and according to the communication quality. Select a virtual path.

The known switch function activates the channel switch control unit 92 in the switch control unit 92, and in response to this, the channel switch control unit 92 controls the connection of the channel switch 85 in the ATM switch 84. A communication path called a connection call is set between the terminal interface 81 and the virtual path interface 83.

The connection call established by the switching mechanism 20 and the virtual path established by the cross-connect mechanism 30 enable the terminal 100 to communicate via the ATM trunk line 400.

FIG. 5 is an AT of the embodiment of the present invention shown in FIG.
It is a systematic schematic diagram which shows the example of interconnection when M electronic exchanges 10a-10c are used.

The cross-connect mechanisms 30a to 30c of the electronic exchanges 10a to 10c are provided with the virtual paths 51 and 52 on the relay line 400a and the relay line 40 by the operation of the respective functional units described above.
The virtual paths 53 and 55 are assigned to 0b, and the virtual path 5 is assigned to the trunk line 400c.
4 and 55 are set respectively.

Here, the virtual path is
A direct link in which a logical line and capacity are predetermined between arbitrary ATM exchanges on a physical transmission network. Each of the ATM trunk lines 400a to 400c has a plurality of logical direct links called virtual paths.

The exchange mechanisms 20a to 20c of the electronic exchanges 10a to 10c adjust the communication quality according to the attributes of the terminals 101 to 103 and 201 to 203 and the medium of the communication information by the operation of the above-mentioned functional units. Then, the virtual path is selected according to the communication quality.

FIG. 2 shows a processing flow for determining the communication quality, and FIG. 3 shows a processing flow for selecting a virtual path according to the determined communication quality. 7 is an operation processing flow of the call processing unit 96.

By the processing operations shown in FIGS.
1 is a connection call 61 between the virtual path 51, a terminal 201 is a connection call 64 between the virtual path 51, a terminal 102 is a connection call 62 between the virtual path 52, and a terminal 202 is a virtual path 52. , A connection call 63 is set between the terminal 103 and the virtual path 54, and a connection call 66 is set between the terminal 203 and the virtual path 53. A connection call 67 is set between the virtual paths 53 and 54.

As a result, the terminals 101 and 201 are replaced by the terminal 10
2 and 202 can be connected to the terminals 103 and 203, respectively.

Now, in the cross-connect mechanisms 30a and 30b in the electronic exchanges 10a and 10b, relay lines are used.
When 400a is congested, virtual path 5
2 is detoured first and the virtual path 55 is used as the detour destination.
Shall be determined in advance.

The cross-connect processing unit 97 in the cross-connect mechanism 30a monitors the cell transmission status (cell delay time, cell discard rate) to the trunk line 400a via the trunk line interface 82, and determines the cell delay time or cell discard rate. When the value becomes worse than a certain reference value, the trunk congestion is detected.

When the congestion of the trunk line is detected, as shown in the flow of FIG. 4, the virtual path 52 is virtualized to the cross-connect mechanism 30a according to the predetermined detour priority and the detour destination virtual path. Instruct the pass 55 to detour.

The cross-connect mechanisms 30a and 30b switch the virtual path 52 in synchronization with the virtual path 55 as shown in FIG. At this time, the switching mechanisms 20a and 20b do not need to perform any processing, so that the connection calls 62 and 65 are maintained as they are, and the communication between the terminals 102 and 202 remains connected without disconnecting the call. ..

[0027]

As described above, according to the present invention, when connecting a terminal and a relay line or between a relay line and a relay line,
The communication quality is determined according to the attribute of the terminal and the medium of the communication information, and the virtual path is selected according to the communication quality, and when the trunk line is congested, the detour of each predetermined virtual path is determined. Since the detour virtual path is determined according to the priority and the virtual path is switched without disconnecting the call, the following effects are obtained.

That is, since the usage rate of each trunk can be adjusted at any time, the load of the trunks in the network can be leveled, and the usage efficiency of the network (the trunk) according to the required quality can be improved.

Further, when a particular trunk line is abnormally congested, the load is distributed to other trunk lines, so that the required quality of the call encountered can be secured.

Further, when the virtual path is switched, the cells are temporarily discarded in a short time, but the virtual path is selected according to the attribute of the terminal and the medium of the communication information. Is preferentially detoured and high-definition voice calls are not detoured.

[Brief description of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing a communication quality determination process of a call processing unit 96.

FIG. 3 is a flowchart showing virtual path selection processing of call processing unit 96.

FIG. 4 is a cross-connect processing unit 9 at the time of trunk congestion.
7 is a flowchart showing the virtual path switching process of No. 7.

FIG. 5 is a schematic connection system diagram showing an application example of an embodiment of the present invention.

FIG. 6 is a schematic connection system diagram when detouring from the connection state of FIG.

[Explanation of symbols]

 10 ATM Electronic Switch 20 Switching Mechanism 30 Cross-Connect Mechanism 81 Terminal Interface 82 Relay Line Interface 83 Virtual Path Interface 84 ATM Switch 85 Channel Switch 86 Virtual Path Switch 91 Switch Control Unit 92 Channel Switch Control Unit 93 Virtual Path Switch Control Unit 94, 95 Signal processing unit 96 Call processing unit 97 Cross-connect processing unit

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Claims (1)

[Claims] 1. An electronic exchange system for accommodating a terminal and a trunk of an asynchronous transfer mode communication method having a plurality of virtual paths whose paths and capacities are logically predetermined and set. A virtual path for determining the communication quality according to the attribute of the terminal or the medium of communication information and selecting one of the virtual paths according to the communication quality when connecting between the relay lines or between the relay lines Selection means, means for predefining the detour priority and detour destination virtual path for each virtual path, congestion detection means for detecting congestion of the relay line, and response to detection of congestion by the congestion detection means And a virtual path switching means for switching the virtual path by determining a bypass virtual path based on the priority of the bypass for each virtual path and the virtual path of the bypass destination. Electronic exchange system.