JP2953422B2 - Cellular timing distribution method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular timing distribution system, and more particularly to AAL1 (ATM adaptation layer type 1: ATM adaptation).
CBR (constant bit rate: C) in which a plurality of channels are multiplexed in Layer type 1
An instantaneous bit rate (VP) signal is transmitted to a different VP (Virtual Path: Virtual) for each channel.
Path) ATM (Asynchronous Transfer Mode: Asynch)
The present invention relates to a cell transfer timing distribution method for distributing the timing of cell formation in an ATM cell conversion method for forming a cell in a form of a roof transfer mode.

[0002]

2. Description of the Related Art When a cell of a CBR multiplexed signal is converted into cells for each channel in the AAL1, data storage is started from the same frame for each channel. Are the same, the cell formation timings overlap and cells are generated in a burst.

[0003] The intensive occurrence of such cells is as follows.
In a channel having the same data length, it always follows periodically.

[0004] Further, in many channels, when the timing of cell formation overlaps, the delay from when a request for cell formation is issued to the last data to be cellized increases.

Therefore, a technique for distributing the cell timings so that they do not overlap with each other has been proposed in, for example, Japanese Patent Application Laid-Open No. H6-161064.

[0006] "ATM cell assembling method" described in this publication
In this example, the amount of dummy data is calculated for each connection in advance, and the operation is started in a state where the dummy data is inserted into a buffer for storing data for each connection, thereby operating the accumulated data amount in an initial state. .

[0007]

The prior art includes:
There were many problems as follows.

First, in order to accommodate the multiplexed CBR data of a plurality of VPs, the VPs having the same data length have the same data accumulation speed and overlap the cell request timings. However, there is a problem that the timing of cell formation is concentrated in time between VPs having the above.

[0009] Further, since the cell timing is fixedly determined at the start of operation, there is a problem that when the accommodated line changes during operation, operation at the optimal cell timing for each VP cannot be performed. .

Furthermore, at the initial stage, it is necessary to calculate and set dummy data for every connection.
There was a problem that initial setting became complicated.

Therefore, a first object of the present invention is to provide AAL1
STM (Synchronous Transfer Mode: Synchronous)
It is an object of the present invention to provide a cell timing distribution method in which cell outputs do not overlap at the same time between a large number of accommodation connections at the time of Transfer Mode / ATM conversion.

It is a second object of the present invention to provide a cell timing distribution system capable of realizing cell timing distribution even when the accommodated line changes during operation.

[0013]

According to the present invention, an AAL
In the ATM cell system for converting a virtual path into an ATM cell for each channel of a constant bit rate signal in which a plurality of channels are multiplexed in the type 1, the number of cells that can be formed in a unit time is limited. The cellization means to be converted is converted into data for each of the virtual paths.
Virtual data that can be cellized by monitoring the data storage status.
The first means for detecting the cell and the timing of the cell formation
Can be output at the unit time so as not to concentrate at the same time
A second means for managing the number of cells
Read so that no more cells are output than can be input
And a third means for controlling the cell timing distribution.

[0014]

Further, the second means receives the virtual path information that can be converted into a cell, and if the number of output cells in the unit time does not reach the number of output cells, the virtual path information of the virtual path is output. An output instruction is issued, and after the number of output cells in the unit time reaches the number of cells that can be output, a process of shifting the data read position of the virtual path by one frame without issuing an output instruction of the virtual path. A cell timing distribution method characterized by performing the above is obtained.

Further, as a first embodiment, there
A buffer having a plane configuration, a CM data section storing control memory data indicating a relationship between a time slot of input data having a frame structure and the virtual path,
A write control unit that manages a write pointer for each virtual path and generates a write address of the input data based on control memory data; and accommodates the input data separately for each virtual path. A cell buffer, a data storage management unit that manages the amount of cells stored for each virtual path, a read cell number management unit that manages the number of cells that can be output in the unit time, A read control unit that manages a read pointer for each path and generates a read address of the cell buffer when a read instruction is issued for each virtual path from the read cell number management unit; A header adding unit for adding an ATM header to the data; and each of the buffer units based on the control memory data from the CM data unit. Cellulating timing distribution scheme is obtained, characterized in that for each Virtual path and a data length management unit for calculating the data length of one frame.

As a second embodiment, a two-sided buffer, a CM data part for storing control memory data indicating a relationship between a time slot of input data having a frame structure and the virtual path are provided. A write control unit that manages a write pointer for each virtual path and generates a write address of the input data based on control memory data, and separates the input data for each virtual path. A cell buffer to be accommodated, a data storage management unit for managing the storage amount of cells for each virtual path, a read cell number management unit for managing the number of cells that can be output in the unit time, A read pointer is managed for each path, and the virtual path that can be read from the data storage management unit is received and the virtual path is received. A read instruction unit for receiving an update instruction and outputs the read pointer Le path pointer management unit,
A pointer management unit that manages the number of cells that can be output in the unit time and determines whether to output a read address to the cell buffer based on whether the number of output cells has reached the number of output cells. A header adding unit for adding an ATM header to the data read from the cell buffer, and one for each virtual path based on the control memory data from the CM data unit.
There is provided a cellular timing distribution method characterized by including a data length management unit for calculating a data length in a frame.

Further, there is provided a cellular timing distribution system wherein the unit time is one frame time.

[0019]

Next, the present invention will be described with reference to the drawings.

First, the operation of the present invention will be described.
The number of read cells within a unit time (for example, one frame time) is counted by the second means for managing the number of cells that can be output per unit time so that the timing of cell formation is not concentrated in the same period, and within one frame time The third means for controlling the reading so as not to output more cells than the number of cells that can be output to the cell outputs a cell read instruction when the number of cells actually output is less than the number of cells that can be output. When the number of cells actually output is equal to the number of cells that can be output, the read head data is shifted by one frame without being instructed to read a cell, and is converted into cells in the next frame time.

In this way, it is possible to prevent the cell timings from being concentrated at one time in each VP. Further, the above operation is applied only to the VP in a state where the cell is not yet output at the initial stage, so that it is possible to disperse the celling timing.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the cell timing distribution system according to the present invention.

Referring to FIG. 1, the cell timing distribution system according to the present embodiment employs a two-sided buffer 1 and a TS (time slot: Time) of input data having a frame structure.
Slot) and VP (virtual path: Virtua)
1 Path), a CM data unit 2 for storing CM (Control Memory) data indicating a relationship with the VP, a write pointer for each VP is managed, and a write address of input data is generated based on the CM data. A write control unit 3, a cell buffer 4 for storing input data for each VP, a data storage management unit 5 for managing the amount of cells stored for each VP, and a read pointer for each VP When a read instruction is issued for each VP from the read-out cell number management unit 7, a read-out control unit 6 that generates a read address of the cell buffer 4 and a read-out cell number management unit 7 that manages the number of cells that can be output in one frame. And celling buffer 4
A header adding unit 8 for adding an ATM header to the data read out from the CMS, and a data length management unit 9 for calculating the data length in one frame for each VP based on the CM data from the CM data unit 2. Prepare.

The buffer 1 has a first surface on which frame data is written from the outside, and a second surface for internally referring to the frame data. CM data part 2 is CM
Data is input to the write control unit 3 and the data length management unit 9.

The write control unit 3 receives the input CM data unit 2
A write address of the input data is generated based on the CM data from the CPU, and writing to the cell buffer 4 is controlled. The cell buffer 4 stores the input data divided for each VP at the write address generated by the write control unit 3.

The data storage management unit 5 receives the write address and the read address of the cell buffer 4 from the write control unit 3 and the read control unit 6, respectively, manages the storage amount of cells for each VP, and converts the cells into cells. Is notified to the read cell number management unit 7.

The read control unit 6 sends the V
When a read instruction is issued for each P, a read address of the cell buffer 4 is generated and read, and the read pointer for one cell is updated. If only a read pointer update instruction is issued, the read pointer of the corresponding VP is updated by one frame.

The read cell number management unit 7 manages the number of cells that can be output in one frame as described above, receives a readable VP from the data storage management unit 5, and issues a read instruction to the read control unit 6. Or a read pointer update instruction is issued.

Next, the operation of this embodiment will be described in detail.

First, the maximum value n of the number of cells that can be output within one frame time is set in the read cell number management unit 7.

After the initialization, the input data is written into the cell buffer 4 based on the write address from the write control unit 3, and the data accumulation management unit 5 manages each VP managed by the write control unit 3. The accumulation state of each VP is monitored from the write pointer of each VP and the read pointer of each VP managed by the read control unit 6. Then, when the data which can be converted into a cell is accumulated, the VP value which can be converted into a cell is output to the read cell number management unit 7.

The read cell number management section 7 counts the number of cell outputs within one frame time. If the number m of celling requests is equal to or less than the maximum value n of the number of cells, the read control unit 6 is instructed to output m cells, and the corresponding VP value is output.
It instructs to update the read pointer for the read data. If the number m of celling requests is larger than the maximum value n of the number of cells, an instruction to output n cells is issued to the read control unit 6 and the corresponding VP value is output, and the read pointer is updated by the read data. For the mn VPs that have not been converted into cells, a read pointer update instruction for one frame is issued and the corresponding VP value is output, so that a cell conversion request is made in the next frame time. I do.

In this manner, the number of cells that can be converted into cells in one frame time is managed, and a request for cell conversion is issued in the next frame time for data that cannot be converted into cells, thereby distributing the timing of cell conversion. It is possible to do.

In the present embodiment, the distributed control of the timing of cell formation is performed after the initialization and the read (cell formation) of V
Since a method of controlling only the timing at which a cell is first output to P is adopted, even if a VP (accommodation line) is newly added or changed during operation, it can be handled.

In this method, since input data is handled in units of frames, coexistence with structured data transfer (SDT) is possible.

FIG. 2 is a block diagram showing a second embodiment of the cell timing distribution system according to the present invention.

In FIG. 2, components having the same functions as those in the first embodiment are denoted by the same reference numerals as those in FIG. 1, and in the present embodiment, the readout in the first embodiment (shown in FIG. 1) is performed. The control unit 6 and the read cell number management unit 7 are
0 and the pointer management unit 11.

That is, the cell timing distribution system of the present embodiment employs a two-sided buffer 1 and a CM data unit 2.
A write control unit 3, a cell buffer 4, a data accumulation management unit 5, a read instruction unit 10 for managing a read pointer for each VP, and a pointer for managing the number of cells that can be output in one frame. A management unit 11, a header addition unit 8, and a data length management unit 9 are provided.

Then, the read control unit 10 receives the readable VP from the data storage management unit 5, outputs a read pointer of the VP to the pointer management unit 11, and issues an update instruction (update for one cell or one frame). Update).

Here, if the update instruction is for one cell, the update is performed by the data length of each VP received from the data length management unit 9.

When the number of output cells does not reach the number of outputable cells, the pointer management unit 11 outputs a read address to the cell buffer 4 and reads the read instruction unit 1.
For 0, a read pointer update instruction for one cell is output.
When the number of cells reaches the number of cells that can be output, the read address is not output to the cell buffer 4 and the read instruction unit 10 is instructed to update the read pointer for one frame.

In the second embodiment, similarly to the first embodiment, the distribution control of the cell timing is performed by first outputting a cell to a VP that has not been read (celled) after initialization. Since a method of controlling only a VP (accommodation line) is newly used or changed during operation, it is possible to cope with the problem.

[0044]

As described above, the present invention provides the AAL1
In the ATM cell scheme for performing ATM cells of different VP plurality of channels for each channel of the multiplexed CBR, cell catheter stage for cell conversion by limiting the number of cells that can be cells into the unit time, VP Means for monitoring the accumulation state of data every time to detect VPs that can be converted into cells, and second means for managing the number of cells that can be output per unit time so that the timing of cell formation is not concentrated at the same time. Means, and the third means for controlling reading so that cells are not output more than the number of cells that can be output in a unit time.
If the P information is received and the number of output cells in the unit time does not reach the number of outputable cells, a VP output instruction is issued, and after the number of output cells in the unit time reaches the number of outputable cells, VP is output. By performing the processing of shifting the VP data read position by one frame without issuing the output instruction of
Surface configuration buffer and frame structure input data TS
Data section for storing CM data indicating the relationship between the VP and the VP; a write control section for managing a write pointer for each VP and generating a write address of the input data based on the CM data; A cell buffer for storing each VP separately, a data storage management unit for managing the amount of cells stored for each VP, a read cell number management unit for managing the number of cells that can be output in a unit time, A read control unit for generating a read address of the cell buffer when a read instruction is issued for each VP from the read cell number management unit, and adding an ATM header to data read from the cell buffer. Header addition part and C from the CM data part
By providing a data length management unit for calculating the data length in one frame for each VP based on the M data, a buffer having a two-plane configuration, and a relationship between TS and VP of input data having a frame structure CM that stores CM data indicating
Manages the data pointer and the write pointer for each VP and
A write control unit for generating a write address of input data based on data; a cell buffer for storing input data separately for each VP; and a data storage management unit for managing the amount of cells stored for each VP A read cell number management unit that manages the number of cells that can be output in a unit time, a read pointer that is managed for each VP, a readable VP is received from the data accumulation management unit, and a read pointer of the VP is pointer managed. A read instructing unit that outputs to the unit and receives an update instruction, and manages the number of cells that can be output within a unit time and reads out to the cell buffer according to whether or not the number of output cells has reached the number of outputable cells A pointer management unit for determining whether or not to output an address;
By providing a header addition unit for adding a header and a data length management unit for calculating the data length in one frame for each VP based on the CM data from the CM data unit, output is possible within a unit time. Since the cells that cannot be output while managing the number of cells are controlled so as to be output in the next frame time, there is an effect that the celling timing in each VP is dispersed.

Further, since only the cell timing for the VP (accommodating line) after initialization can be controlled,
This has the effect that even if a VP (accommodation line) is newly added or changed during operation, it can be handled.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a cell timing distribution system according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the cell timing distribution system according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input buffer 2 CM data 3 Write control part 4 Cell buffer 5 Data accumulation management part 6 Read control part 7 Read cell number management part 8 Header addition part 9 Data length management part 10 Read instruction part 11 Pointer management part

Claims (5)

(57) [Claims] 1. A cell which can be cellized within a unit time in an ATM cellization system for converting an ATM cell of a virtual path different for each channel of a constant bit rate signal in which a plurality of channels are multiplexed in AAL type 1. The celling means for limiting the number of cells into cells is the bar
Monitor data accumulation status for each path and create cells
First means for detecting a possible virtual path;
The above-mentioned unit is used so that the timing of cell
Second means for managing the number of cells that can be output for each unit time
More cells than can be output in the unit time
And a third means for controlling reading so as not to be applied . 2. The cell according to claim 2, wherein said second means is a cell capable of being made into a cell.
Receive the virtual path information and output the
If the number of cells has not reached the number of cells that can be output,
Command to output a virtual pass and output during the unit time.
After the number of power cells reaches the number of cells that can be output, birch
The virtual path without issuing a command to output the virtual path.
2. The cell timing distribution method according to claim 1, wherein the data read position is shifted by one frame . 3. A two-sided buffer and a frame-structured buffer.
Time slot of input data and said virtual path
Stores control memory data indicating the relationship between
CM data part and write for each virtual path
Manages pointers and uses control memory data
Write control unit for generating a write address of the input data
And dividing the input data for each of the virtual paths.
And a cell buffer for each virtual path
A data storage management unit that manages the storage amount of cells for each
Number of read cells that manages the number of cells that can be output in the unit time
The management unit and a lead point for each virtual path
Data from the read cell number management unit.
If a read instruction is issued for each pass, the cell buffer is read.
A read control unit for generating an address, and the cell buffer
To add an ATM header to the data read from
Data adding section and the control from the CM data section
.Each virtual path based on memory data
A data length management unit for calculating the data length in one frame
Cellulating timing distribution method according to claim 1 or 2, wherein further comprising a. 4. A two-sided buffer, a CM data section storing control memory data indicating a relationship between a time slot of input data having a frame structure and the virtual path, and a CM data section for each virtual path. A write control unit that manages a write pointer and generates a write address of the input data based on control memory data; a cell buffer that stores the input data separately for each virtual path; A data storage management unit that manages the amount of cells stored for each virtual path, a read cell number management unit that manages the number of cells that can be output in the unit time, and a read pointer that is managed for each virtual path The data storage management unit that can read the data
Receive a virtual path and restore the virtual path.
Output a pointer to the pointer management unit and receive an update instruction.
A reading instruction unit for extracting and a cell that can be output within the unit time
The number of cells output by managing the number reaches the number of cells that can be output.
Read-out address to the cell buffer
A pointer management unit for determining whether or not to output the address, a header addition unit for adding an ATM header to the data read from the cell buffer, and the control memory data from the CM data unit. claim wherein the further comprising a data length management unit for calculating the data length of one frame for each virtual path to preparative 1 or
Cellulating timing distribution scheme other 2 wherein. 5. The cell of the timing distribution method of claims 1 to 4, wherein said unit time is characterized by this <br/> and a 1 frame time.