JPH06209332A - Isochronous information transfer system for bus type distributed switching network - Google Patents

Abstract

PURPOSE:To transfer isochronous information in a cell unit in a bus type distributed switching network where information is transferred in the asynchronous transfer mode. CONSTITUTION:A slot for isochronous information is constituted with a slat provided with a contention control area and a communication area in a cell unit, and a central controller 2 is provided with a function 12 which reports intervals of occurrence of the slot for isochronous information to an access unit 3 at the bus terminal. The access unit 3 at the bus terminal is provided with a storage device 15 having the number of words corresponding to the cell. period and a function 16 which reads out written data in order after write of the identifier of isochronous information to the storage device 15 with the address difference corresponding to intervals of the occurrence of the slot reported from the central controller 2 to generate the slot for isochronous information. Each access unit 3 is provided with a function 14 which recognizes the timing, at which its own isochronous information should be sent, by identifier described in the slot for isochronous information communication.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isochronous information transfer system in a bus type distributed switching network which transfers information in an asynchronous transfer mode.

[0002]

2. Description of the Related Art FIG. 2 is an overall configuration diagram of a bus type distributed switching network that transfers information in an asynchronous transfer mode. As shown in the figure, the bus type distributed switching network has a configuration in which a communication device 4 is connected to each access unit 3 connected to a central management device 2 by a bus 1. By controlling the operation, transmission of isochronous information or non-isochronous information from each communication device 4 is controlled.

In such a bus type distributed switching network, the bus 1
The access unit 3 (the access unit 3 shown by the arrows (a) and (b) in FIG. 2) at the end of is equipped with a function of generating a 53-byte time slot for transmitting information.

In the conventional bus type distributed switching network, the configuration of the time slot is different for isochronous information communication and for non-isochronous information communication. In the case of a time slot for isochronous information communication, The 53 bytes are further divided into 1-byte units and assigned to each call (or each access unit 3) to have a slot configuration.

When each access unit 3 transmits isochronous information, the central control unit 2 is notified of the amount of information transmission, whereby the central control unit 2 judges whether or not communication is possible and accesses the information later. A band allocation calculation is performed on the unit 3, the band (area) to be allocated is notified to the access unit 3 that is the source of the isochronous information and the access unit 3 that is the destination, and the isochronous information is transmitted. Reserve the byte area of the time slot that should be used.

On the other hand, in the case of the conventional bus type distributed switching network, for non-isochronous information, distributed contention control is performed in cell units, which is a basic information unit of information transfer in the asynchronous transfer mode, and information transfer is performed. There is.

[0007]

However, as described above, in the conventional bus type distributed switching network, the information transfer method is different between the non-isochronous information and the isochronous information. Is transferred in units of cells, and isochronous information is transferred in units of bytes (8 bits). Therefore, the bus end access unit 3 that generates a time slot must be equipped with a storage device having a different control method for each of isochronous information communication and non-isochronous information communication. There was a drawback that the physical burden became large.

Further, when the isochronous information is transferred, the cell, which is a basic information unit of information transfer in the asynchronous transfer mode, is destroyed and transferred, and accordingly, the cell synchronization is also performed on the receiving side. It is necessary to establish separately for each type (that is, non-isochronous information and isochronous information), and there is also a drawback that synchronization control on the receiving side becomes complicated.

Further, when transferring isochronous information, since information loss is in byte units, there has been a drawback that processing for cell order management and loss management becomes complicated.

The present invention has been made in view of the above circumstances, and it is necessary to separately prepare storage devices having different control systems for isochronous information communication and non-isochronous information communication when transferring information. It is possible to reduce the hardware burden without having to do so, and to prevent the cell synchronization control on the receiving side from becoming complicated, and at the same time prevent the processing for cell order management and loss management from becoming complicated. An object of the present invention is to provide an isochronous information transfer method in a bus type distributed switching network.

[0011]

An isochronous information transfer system in a bus type distributed switching network according to the present invention is an isochronous information transfer system in a bus type distributed switching network which transfers information in an asynchronous transfer mode. The improved time slot for isochronous information communication is a cell unit, which is the basic information unit for information transfer in the asynchronous transfer mode, and a contention control area for describing contention control information and communication data. The slot structure is provided with a communication area in which information such as a slot identifier that allows the access unit to determine the usable slot can be described.

Then, the central management unit for controlling the operation of the access unit connected to the bus calculates the generation interval of the time slot for isochronous information communication and notifies the access unit at the end of the bus of the slot generation request. Equipped with a sending function.

Further, each access unit connected to the bus monitors the identifier described in the time slot transmitted on the bus to determine the timing at which the isochronous information of its own access unit or its own call should be transmitted. Equipped with a timing judgment function to recognize.

Further, the access unit which becomes a bus end and generates a time slot is equipped with a storage device having a word number for a cell period which is a basic information unit of information transfer in the asynchronous transfer mode. The time for isochronous information communication is obtained by writing the identifier of the isochronous information in the storage device at the address difference according to the time slot occurrence interval calculated by the central management device and sequentially reading the data written in the storage device. It is equipped with a function to generate slots.

With the above new configuration, transfer of isochronous information in units of cells is realized.

[0016]

In the isochronous information transfer system in the bus type distributed switching network according to the present invention, the isochronous information transfer is also executed in the cell unit which is the basic information unit of the information transfer in the asynchronous transfer mode. , It is not necessary to separately prepare a storage device having different control methods for the isochronous information communication and the non-isochronous information communication in the access unit at the end of the bus.
The hardware burden can be reduced.

Further, since the transfer of isochronous information is performed on a cell-by-cell basis as in the case of non-isochronous information, the receiving side separately performs cell synchronization processing for non-isochronous information and isochronous information. It is also possible to prevent the cell synchronization control on the receiving side from becoming complicated, and at the same time to prevent the processing for cell order management and loss management from becoming complicated. It becomes possible to build a system of a switching network.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an isochronous information transfer system in a bus type distributed switching network according to the present invention will be described below with reference to FIGS.

The isochronous information transfer method in the bus type distributed switching network according to one embodiment of the present invention is an asynchronous transfer mode (AT
M) is an improved isochronous information transfer method in a bus type distributed switching network for transferring information. The schematic structure of the bus type distributed switching network is as shown in FIG. That is, the communication device 4 is connected to each access unit 3 connected to the central management device 2 by the bus 1. By controlling the operation of each access unit 3 by the central management device 2, each communication unit 4 is connected. It controls the transmission of isochronous or non-isochronous information from the device 4. Also,
The access unit 3 at the end of the bus 1 (the access unit 3 indicated by arrows (a) and (b) in FIG. 2) is equipped with a function of generating a 53-byte time slot for transmitting information. ing.

The time slots generated by the access unit 3 at the end of the bus are for isochronous information communication and for non-isochronous information communication. In this embodiment, the time slot is for isochronous information communication. As shown in FIG. 3, a time slot is a cell unit (fixed length of 53 bytes) which is a basic information unit of information transfer in the asynchronous transfer mode, and one of the 53 bytes is used.
Bytes are allocated to the contention control area 6 and the remaining 52 bytes are allocated to the communication area 7 in a slot configuration.

The contention control area 6 is an area for describing information for enabling discrimination between isochronous information communication and non-isochronous information communication and other information necessary for contention control. is there. Further, a transfer control information field 8 of 4 bytes and a communication information field 9 of 48 bytes are set in the communication area 7 of 52 bytes. Here, the transfer control information field 8 is an area in which information such as a slot identifier for making it possible to determine a slot that can be used by the corresponding access unit is written.

By configuring the time slot for isochronous information communication in this way, for example, one cell is used as a header of 5 bytes (1 byte of 5 bytes of the header is used as the contention control area 6). It is possible to process the isochronous information on a cell-by-cell basis, as in the case of the non-isochronous information of the slot configuration that is distributed to the information field of 48 bytes).

Also, in the case of this embodiment, as shown in FIG. 1, the access unit 3 transmits isochronous information to the central management unit 2 as a new function which the conventional unit does not have. When a call request is issued, a slot generation request sending function 12 for calculating the generation interval of the time slot for isochronous information communication and notifying the access unit 3 at the end of the bus
Is equipped with.

Each access unit 3 connected to the bus 1 has a timing judgment function 1 as shown in FIG.
In the case of the access unit 3 which is equipped with 4 and which is the end of the bus, a storage device 15 and a time slot generation function 16 are further installed.

The timing judgment function 14 monitors the slot identifier written in the time slot transmitted on the bus 1 and recognizes the timing at which the isochronous information of the own access unit or self call should be transmitted. Is.

The storage device 15 and the time slot generating function 16 are necessary for generating a time slot when the position corresponding to the access unit 3 at the end of the bus is reached.

The storage device 15 has a word number corresponding to a cell period which is a basic information unit of information transfer in the asynchronous transfer mode, and the slot structure of the time slot for isochronous information communication is shown in FIG. Since it has a cell-based structure, it is used for both generation of slots for isochronous information communication and generation of slots for non-isochronous information communication.

Based on the notification from the slot generation request sending function 12 of the central control unit 2, the time slot generation function 16 stores the address difference according to the time slot generation interval calculated by the central control unit 2. Device 15
Is a function of generating a time slot for transmitting isochronous information by writing a slot identifier of isochronous information and the like and sequentially reading the data written in the storage device 15.

The processing procedure by the isochronous information transfer method in the bus type distributed switching network of one embodiment will be described below with reference to FIGS. 4 and 5.

FIG. 4 shows a calling procedure for one-way communication, and FIG. 5 shows a calling procedure for two-way communication.

First, the call origination access unit 20 which is the originator of the isochronous information issues a call origination request 21 which is a transmission request of the isochronous information to the central management unit 22 (the central management unit 2 in FIG. 2). Output to. The call request 21 includes information such as communication speed and communication destination notification.

The central control unit 2 which has received the call request 21
2 examines the total communication capacity in the bus type distributed switching network to judge whether the call can be executed.
A slot identifier is secured as a time slot for isochronous information communication, and the generation interval of the time slot for isochronous information communication (for example, every 200 slots) is calculated by the slot generation request sending function 12 described above. Then, a slot generation request 24 having these slot identifiers and time slot occurrence intervals as contents is notified to the end access unit 25 at the end of the bus. In addition, the central management device 22
While transmitting the slot generation request 24 to the end access unit 25, the communication availability determination request 27 for inquiring the communication availability to the incoming access unit 26 that is the destination of the isochronous information. Is sent.

The end access unit 25 to which the central management unit 22 sends the slot generation request 24 is only the end access unit on the one end side where the calling access unit 20 exists in the case of the one-way communication shown in FIG. However, in the case of the bidirectional communication shown in FIG. 5, the end access units at both ends are targets for transmission.

The time slot generation function 16 described above operates in the terminal access unit 25 which receives the slot generation request 24 from the central management unit 22, and the central management unit 22
The identifier of the isochronous information is written in the storage device 15 with the address difference according to the time slot occurrence interval notified from the. Further, the isochronous information communication slot is sent to the bus by sequentially reading the data written in the storage device 15.

A specific example of the process for generating the isochronous information communication slot in the terminal access unit 25 will be described. For example, a bus type distributed switching network according to an embodiment is used as a level 1 (transfer rate of 155.52 Mbp) in an asynchronous transfer mode.
s, when using VC-4), the minimum communication speed is 64k
It is assumed that the end access unit 25 is equipped with a storage device 15 of 2430 words. In this case, the writing of the identifier of the isochronous information communication slot to the storage device 15 requires one word (1
2 words at 28 kbps transfer) are written at intervals of 1215 words. Then, by sequentially reading the written information, a reserved slot for isochronous information communication is generated.

In the transfer control information field of the slot transmitted from the end access unit 25 to the bus as the isochronous information communication slot, the calling access unit 20 notified from the central management unit 22 is specified. The slot identifier is written.

On the other hand, if the incoming call access unit 26 receives the communication availability judgment request 27 from the central management unit 22, if the communication is possible, it returns a communication availability response 28 to that effect to the central management unit 22. Upon receiving the communication enable response 28 from the incoming call access unit 26, the central management device 22 sends out a communication start enable response 29 to the calling access unit 20.

The communication startable response 29 includes the contents for notifying the slot identifier for isochronous information communication, and is only for the calling access unit 20 in the case of one-way communication, but for the two-way communication. In this case, it is also sent to the incoming call access unit 26 as shown in FIG.

The calling access unit 20, which has received the communication start enable response 29 from the central management unit 22, monitors the slot identifier described in the time slot transmitted on the bus and allocates it to its own access unit. When the acquired isochronous information communication slot is detected, the communication data as the isochronous information to be transmitted is written in the assigned portion of the communication area of the slot.

In the isochronous information transfer method in the bus type distributed switching network according to the embodiment described above, the transfer of isochronous information is also executed in units of cells, which is a basic information unit of information transfer in the asynchronous transfer mode. Therefore, it is not necessary to separately prepare a storage device having different control methods for the isochronous information communication and the non-isochronous information communication in the access unit at the end of the bus, which reduces the hardware load. can do.

Also, since the transfer of isochronous information is performed on a cell-by-cell basis as in the case of non-isochronous information, the receiving side separately performs cell synchronization processing for non-isochronous information and isochronous information. It is also possible to prevent the cell synchronization control on the receiving side from becoming complicated, and at the same time to prevent the processing for cell order management and loss management from becoming complicated. It becomes possible to build a system of a switching network.

[0042]

As is apparent from the above description, in the isochronous information transfer method in the bus type distributed switching network according to the present invention, the isochronous information transfer is performed by the basic information unit of the information transfer in the asynchronous transfer mode. Since it is executed in units of cells, it is not necessary to separately prepare storage devices having different control methods for isochronous information communication and non-isochronous information communication in the access unit at the end of the bus. The hardware burden can be reduced.

Also, since the transfer of isochronous information is performed on a cell-by-cell basis as in the case of non-isochronous information, the receiving side separately performs cell synchronization processing for non-isochronous information and isochronous information. It is also possible to prevent the cell synchronization control on the receiving side from becoming complicated, and at the same time to prevent the processing for cell order management and loss management from becoming complicated. It becomes possible to build a system of a switching network.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a bus type distributed switching network.

FIG. 3 is a slot configuration diagram of an isochronous information communication slot according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a calling procedure during one-way communication according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a calling procedure during bidirectional communication according to an embodiment of the present invention.

[Explanation of symbols]

 1 Bus 2, 22 Central Management Device 3 Access Unit 6 Contention Control Area 7 Communication Area 8 Transfer Control Information Field 9 Communication Information Field 12 Slot Generation Request Transmission Function 14 Timing Judgment Function 15 Storage Device 16 Time Slot Generation Function 20 Calling Access Unit 25 Terminal access unit 26 Incoming call access unit

Claims (1)

[Claims] 1. A isochronous information transfer method in a bus type distributed switching network for transferring information in an asynchronous transfer mode, wherein a time slot for isochronous information communication is a basic information of the information transfer in the asynchronous transfer mode. A contention control area for describing contention control information and a communication area where information such as a slot identifier for distinguishing a slot usable for an access unit can be described in addition to communication data in a cell unit as a unit. The central management unit that controls the operation of the access unit connected to the bus has a slot configuration including and calculates the generation interval of the time slot for isochronous information communication and notifies the access unit at the end of the bus. It is equipped with a slot generation request sending function, and each access unit connected to the bus is described in the time slot sent on the bus. It is equipped with a timing judgment function that recognizes the timing to send the isochronous information of its own access unit or its own call by monitoring the identifier that is A storage device having a number of words corresponding to a cell cycle, which is a basic information unit of information transfer in a transfer mode, is provided, and the storage device is isochronous with an address difference according to a time slot generation interval calculated by the central management device. Controlling the transfer of isochronous information by equipping it with a time slot generation function that generates a time slot for isochronous information communication by writing the identifier of sex information and reading the data written in the storage device in order. An isochronous information transfer method in a bus type distributed switching network.