JP2000269984A - Asynchronous transfer mode exchange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an ATM exchange 1 to conduct signaling with a small configuration, even when the number of channels is increased. SOLUTION: Terminal side inf(interfaces) 3-1 to 3-m are respectively provided with address conversion sections 7-1 to 7-m, network side inf 4-1 to 4-n are respectively provided with address conversion sections 8-1 to 8-n, and a common SIG(signaling) circuit is provided. Then the address conversion sections causes 7-1 to 7-m, 8-1 to 8-n to newrite the address of VCI/VPI of the header part of an ATM cell to give the ATM cell to the common SIG circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM switching apparatus for exchanging asynchronous transfer mode (hereinafter referred to as "ATM") cells.

[0002]

2. Description of the Related Art In recent years, in order to realize a multimedia communication environment, B-ISDN (B-ISDN) is a communication technology capable of transmitting a large amount of information such as moving image information instantaneously and performing interactive (two-way) communication at a higher speed. Broadband Integrated S
ATM (Digital Network) is attracting attention, but ATMs use the B-IS
This is the basic technology that supports DN technology.

[0003] ATM is a communication mode in which communication information is divided into cells each of which is a bit string having a short length and transferred asynchronously as in packet communication. This ATM allows multiplexing on a cell basis without discriminating between line data and packet data, does not need to synchronize with transmission line timing, and flexibly transfers data even in services requiring different transmission speeds. Since the transfer can be performed, the transmission line can be used effectively.

[0004] The header at the head of the ATM cell has a VPI
(Virtual Path Identifier), VC
I (Virtual Channel Identifier) is added.

[0005] The ATM cells include signaling cells and user information cells. The signaling cells contain signaling information necessary for control such as establishment and release of an ATM connection.

[0006] In the ATM network, an ATM cross connector and an ATM switching device are arranged. This ATM
The cross connector is a virtual path handler that connects the virtual path link by rewriting the VPI in the header of the ATM cell. The ATM switching device terminates the virtual path handler and
This is a virtual channel handler that connects a virtual channel by rewriting the VCI of the TM cell.

This ATM switching device includes an address conversion unit, a signaling circuit, and a common switch. When an ATM cell for signaling is transferred to the ATM switching device, a signaling circuit sets which ATM switching device in the network is to be passed based on the signaling information included in the ATM cell. Then, based on this setting, the VCIs of the signaling and user ATM cells are rewritten by the address translation unit, and the common switch is switched to perform routing.

[0008]

The conventional AT
In the M exchange, this signaling circuit is provided for each terminal and each network.

This is based on UNI (User Network Interface).
Broadcasting is necessary when acquiring a link number in e),
This is because the recognition address for the ATM signaling at this time is set to a specific value determined by the international standard, and it is necessary to make the ATM signaling information recognized for each physical interface.

However, if a signaling circuit is provided for each terminal or network, the number of signaling circuits increases with an increase in the number of lines, and the larger the system, the more space is required and the higher the cost. Accordingly, there is a need for an ATM switching device that can perform signaling with a small configuration even if the number of lines increases.

[0011]

SUMMARY OF THE INVENTION In view of the above problems, the present invention employs the following configuration. <Arrangement 1> An ATM switching apparatus according to the invention of claim 1 is provided for each terminal and network, receives a cell formatted in an asynchronous transfer mode from the terminal or network, and receives a virtual channel included in the cell. An interface for rewriting an identifier; a signaling circuit for setting and controlling a virtual channel for each terminal and a network based on the signaling information when the received cell is a signaling cell containing signaling information; An apparatus comprising: a common switch for switching a transfer destination; and a control circuit for controlling the common switch based on a virtual channel identifier rewritten by the interface, wherein the signaling circuit is shared by all terminals and a network. Connected to a common switch as a circuit, the interface The virtual channel identifier of the cell when the cell for the received cell signaling is configured to include an address conversion means for rewriting the address of which destination the common signaling circuit.

<Structure 2> An ATM switching apparatus according to the second aspect of the present invention is provided for each terminal, and is provided for each network with a terminal side interface for transmitting and receiving cells to and from the terminal. A network interface for transmitting and receiving cells and, when a cell received by the network interface is a signaling cell including signaling information, setting and control of a virtual channel for a terminal and a network are performed based on the signaling information. An apparatus comprising: a signaling circuit; a common switch for switching a transfer destination of the cell; and a control circuit for controlling the common switch based on a virtual channel identifier rewritten by the interface. Circuit, while connecting to the network through signaling circuits and common switches. A switch for switching to any one of the above, and when the cell received from the network is a cell for user information including user information, the cell is transferred to a common switch, and the cell received from the network includes signaling information. In the case of a signaling cell, switching control means for switching the switch is provided to transfer the cell to the signaling circuit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. <Example 1> In Example 1, a signaling circuit is connected to a common switch so that common signaling can be performed for ATM cells input from each terminal and network, so that a large number of lines does not result in a large configuration. It is like that.

FIG. 1 is a block diagram showing the configuration of the first embodiment. The ATM switching apparatus 1 includes a control circuit 2 and a terminal-side interface (referred to as “terminal-side inf” in the figure) 3-1.
To 3-m and a network-side interface (in the figure, "network-side in
f ”) 4-1 to 4-n and a common switch (in the figure,
It is configured to include a “common SW” 5 and a common signaling circuit (referred to as “common SIG circuit” 6) in the figure.

The terminals inf3-1 to 3-m are connected to each terminal 11
ATM formatted AT from -1 to 11-m
The M cell is received and transferred to the common SW5, and the ATM cell transferred from the common SW5 is transmitted to each of the terminals 11-1 to 11-m.

FIG. 2 is a diagram showing the structure of this ATM cell. Note that this cell format is determined by an international standard, and its address value is also determined.

The ATM cell is composed of 53 bytes consisting of a header (Header) part and a payload (Payload) part. The header part and the payload part each have 5 bytes.
It is composed of 48 bytes.

In the header section, GFC (Generic
Flow Control: general flow control), VPI, VC
I, PT (Payload Type), CLP
(CellLoss Priority: cell loss priority display) field is arranged.

The GFC field indicates the AT between the terminal and the network.
This field is used as a means for avoiding collision and congestion of M cells. The VPI and VCI fields are ATM
This field is used for determining (routing) a communication path of a cell.

The PT field is a field used to identify the purpose of the information to be transferred. The CLP field is a field used to identify the priority at which ATM cells are discarded during congestion. The signaling information is recorded in the payload section.

The terminals inf3-1 to 3-m are provided with address converters 7-1 to 7-m, respectively. The address conversion units 7-1 to 7-m are connected to the terminals 11-1 to 11-1 respectively.
It converts the address of the ATM cell transmitted from 11-m, and is connected to each of the terminals 11-1 to 11-m.

The network-side infs 4-1 to 4-n similarly have address converters 8-1 to 8-n, respectively, and the address converters 8-1 to 8-n are respectively connected to the network. The address conversion units 7-1 to 7-m and the address conversion units 8-1 to 8-n correspond to an address conversion unit. The address conversion units 7-1 to 7-m and 8-1 to 8-n include:
A device for converting the user information into an address in the device is used.

The common SW5 includes both inf3-1 to 3-m,
4-1 to 4-n are connected while being switched. The common SIG circuit 6 is a circuit that performs signaling of the entire ATM switching device 1. The control circuit 2 controls the entire device including the common SW5.

<Operation of Specific Example 1> Next, the operation will be described. Here, a case where an ATM cell is transmitted from the terminal 11-m to the switching device 1 will be described.

The ATM cells are respectively input to the address conversion units 7-m. The cell format is determined by the international standard as described above, and its address value is also determined. However, in the switching device 21, the cell format is not limited to this cell format.

Therefore, when the ATM cell is a signaling cell containing signaling information, the address translator 7
In the case of −m, the VCI provided in the header of the ATM cell is converted into an address specific to signaling to the common SIG circuit 6 so that the VCI does not overlap with other VCIs.

The common SW 5 is switched and controlled by the control circuit 2 in accordance with the address, and the address converted A
The TM cell is input to the common SIG circuit 6 via the common SW5.

The signaling information of the ATM cell is a common SI
It is read by the G circuit 6, and the location of the interface is recognized. Also, the original VPI and VCI types are inversely converted and the types are also recognized, and the processing of the signaling information of the payload portion is performed according to international standards based on the VPI and VCI types. After the processing of the signaling information is performed, the address of the ATM cell is inversely converted into the original VPI and VCI, and output from the network side inf4-n to the network 13.

<Effects of Specific Example 1> As described above, in Specific Example 1, the terminal-side inf 3-1 to 3-m and the network-side inf 4-
Address conversion units 7-1 provided in each of 1 to 4-n
7-m, 8-1 to 8-n, the SIG circuit is shared and connected to the common SW5, and the address conversion is performed so that the ATM cell is transmitted to the common SIG circuit 6. , The signaling can be performed with a small configuration, and the cost can be greatly reduced.

<Specific Example 2> In specific example 2, signaling is performed in a distributed manner on the network side. FIG. 3 is a block diagram showing the configuration of the second embodiment. In the specific example 2, the network-side SIG circuits 2
1-1 to 21-n and switches (hereinafter, referred to as “SW”) 22-1 to 22-n.

The network-side SIG circuits 21-1 to 21-n are circuits for performing signaling, and the switches SW22-1 to 22-n are switches for switching between communication routes.
In addition, in the specific example 2, although the number of signaling circuits is increased as compared with the specific example 1, the network side inf4-1 to 4-n
Is usually smaller than the terminal-side inf 3-1 to 3-m, and the configuration is smaller than in the related art. Also, each SW
22-1 to 22-n are also contained in one small device element having a small number of routes, and have a simple and compact structure.

FIG. 4 is an explanatory diagram showing the input / output relationship of the ATM cell. This correspondence relationship is stored in the control circuit 2, and the control circuit 2 determines each SW 22-1 to 22-
n switching control is performed. This control circuit 2 corresponds to the switching control means. Note that the same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

<Operation of Embodiment 2> FIG. 5 is an explanatory diagram showing the operation of Embodiment 2. When the address value of the VCI / VPI of the ATM cell input from the network 13 is "100", the SW 22-1 is switched by the control circuit 2 based on the input / output relationship of FIG. 4, and the output route 16a is selected. . AT
The M cell is connected to the network side SIG circuit 21-1 via the SW 22-1.
, And the address value of the input VCI / VPI is rewritten to “200” as shown in FIG. The user information is directly input to the common SW5, and the ATM cell is output to the terminal via the common SW5.

FIG. 6 is an explanatory diagram showing the operation when a failure occurs in the ATM switching device 1. As shown in FIG. 6, if a failure occurs in the network-side SIG circuit 21-1, the communication route via the SW 21-1 is disconnected, but the communication route via the network-side inf4-n fails. Maintained without being affected by

<Effect of Specific Example 2> As described above, in the specific example 2, since the signaling is distributed on the network side, even if a failure occurs in a certain SIG circuit on the network side, other signaling is performed. The communication route is not affected, and the effect of the failure can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a specific example 1 of an ATM switching device according to the present invention.

FIG. 2 is an explanatory diagram showing a structure of an ATM cell.

FIG. 3 is a block diagram showing a configuration of a specific example 2 of the ATM switching device according to the present invention.

FIG. 4 is an explanatory diagram showing an input / output relationship of an ATM cell of a specific example 2;

FIG. 5 is an explanatory diagram showing an operation of a specific example 2.

FIG. 6 is an explanatory diagram illustrating an operation of a specific example 2 when a failure occurs.

[Explanation of symbols]

1 ATM switching device 2 Control circuit 3-1-3-m Terminal side interface (terminal side in
f) 4-1 to 4-n Network-side interface (network-side inf) 5 Common switch (SW) 6 Common signaling (SIG) circuit 7-1 to 7-m, 8-1 to 8-n Address conversion unit 21- 1-21-n network side signaling (SIG) circuit 22-1-22-n switch (SW)

Claims (2)

[Claims] An interface provided for each terminal and network, for receiving a cell formatted in an asynchronous transfer mode from the terminal or network and rewriting a virtual channel identifier contained in the cell, and an interface for receiving the cell, In the case of a signaling cell including signaling information, based on the signaling information, each terminal, a signaling circuit for setting and controlling a virtual channel for a network, a common switch for switching a transfer destination of the cell, and the interface A control circuit for controlling a common switch based on the rewritten virtual channel identifier, wherein the signaling circuit is connected to the common switch as a common signaling circuit shared by all terminals and networks. The interface is a received cell Asynchronous transfer mode switching device, wherein a virtual channel identifier of the cell, was configured with an address conversion means for rewriting the address of which destination the common signaling circuit when the cell for signaling. 2. A terminal interface provided for each terminal, for transmitting and receiving cells to and from the terminal, and provided for each network;
A network-side interface for transmitting / receiving cells to / from the network, and, when the cell received by the network-side interface is a signaling cell including signaling information, a virtual channel for the terminal and the network based on the signaling information. An asynchronous transfer mode switching device comprising: a signaling circuit that performs setting and control; a common switch that switches a transfer destination of the cell; and a control circuit that controls the common switch based on a virtual channel identifier rewritten by the interface. The network-side interface comprises the signaling circuit, and further comprises a switch for switching a connection with the network to one of the signaling circuit and the common switch, and a cell received from the network for user information including user information. If the cell is Transferred to the switch,
When the cell received from the network is a signaling cell including signaling information, an asynchronous transfer mode switching device includes switching control means for switching the switch so as to transfer the cell to a signaling circuit.