JPH0697961A - Access control system for atm multiple bus - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to an access control system for an ATM multiplex bus, and an object thereof is to provide an access control system for an ATM multiplex bus having good operability. [Structure] A plurality of terminals 3 are connected via a buffer 4 to an empty cell generator 10 that generates an empty ATM cell from the upstream side and a bus connected to the empty cell generator 10, and a sequential flow from the upstream is performed. In the ATM multiplexing system for allocating the vacant cells to a plurality of calls, the vacant cell generator 10 gives the vacant cells generated from the upstream of the bus a terminal ID which can use the vacant cells, and the subscriber line. 5, a media access device 6 is provided which compares the ID of the read empty cell with the ID of its own and compares and collates with its own ID, and controls the sending out of the buffer 4 according to the result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM multiple bus access control system, and more particularly to a system for allocating empty cells coming from the upstream of a bus to ATM cells sent from a plurality of terminals sharing a bus-like transmission path. .

[0002]

2. Description of the Related Art There may be a plurality of terminals that simultaneously send cells to a single bus. In order to avoid data collision on the bus at this time, an ATM multiplex system in which a FIFO (First In First Out) buffer is provided in each terminal or between each terminal and the bus is targeted.

This multiplexing system can be applied when one subscriber line is shared by a plurality of users (terminals). FIG. 5 is a conceptual diagram of a conventional system. Empty cell generator 1
From, empty cells are output at a constant cycle. A plurality of (here, three) terminals 3 are connected to the subscriber line 2. Reference numeral 4 is a FIFO buffer connected to each terminal 3.

In the system thus constructed,
Subscriber line 2 from terminal 3 near upstream (eg from terminal 1)
Since the terminal 3 is occupied, the terminal 3 on the downstream side is kept waiting. The FIFO buffer 4 is provided to avoid data collision on the subscriber line 2. Here, the user premises network is configured with the components 1 to 4. The subscriber line 2 output from the user premises network is connected to the public network. This multiplexing system
It can be used when one subscriber line is shared by multiple subscribers.

FIG. 6 is another conceptual diagram of the conventional system.
This system shows an example in which ATM cells arriving from several subscriber lines in a public network are multiplexed (concentrated) on a high-speed (622.08 Mbps) line.

[0006]

DQ is an ATM multiplexing system based on a bus or ring-shaped transmission medium.
DB (Distributed Queue Dual)
Bus) protocol and ATMR (ATM Ring)
Protocols have been proposed. The DQDB system uses two signal lines, one of which is used as a down line and the other of which is used as an up line, as shown in FIG. For example, if 2A is an up line, 2B is a down line. These subscriber lines 2A,
The terminal 3 is connected between 2B. An empty cell generator 1A is connected to the subscriber line 2A, and an empty cell generator 1B is connected to the subscriber line 2B.

Since all of them aim for distributed control, each terminal sharing a transmission medium manages access to this medium in a distributed manner, and the functions of these media access devices (MAU) are considerably heavy. . DQD
In B, it is necessary to manage the number of transmission requests coming from downstream and the number of empty slots coming from upstream in each MAU.
In TMR, since only the number of cells that have not reached the predetermined window size is transmitted, it is necessary to perform control such that each MAU overwrites its own ID in order to indicate that it is still transmitting. is there.

Further, if there is a terminal that transmits cells in burst (continuously) in both SQDB and ATMR, cells are transmitted to the transmission medium without alleviating the burstiness. Therefore, the traffic characteristics of the buffer that receives cells arriving from this transmission medium are not very good.

Further, since these terminals depend on the cell generation state from other terminals to determine whether or not their own terminal can receive the cell, that terminal is, for example, CBR (Constant).
Bit Rate) Even if cell generation requests are issued at regular intervals, the cells of the call are not evenly spaced after being multiplexed. That is, fluctuations occur. Therefore, on the network side receiving the cell stream thus multiplexed, the UPC (Us
When performing the age Parameter Control), it is necessary to consider the fluctuation and make the criteria for detecting a violation gentle.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an access control system for an ATM multiplex bus having good operability.

[0011]

FIG. 1 is a block diagram showing the principle of the present invention. The same parts as those in FIG. 5 are designated by the same reference numerals. The system shown in the figure is empty ATM from the upstream side.
A plurality of terminals 3 are connected via a buffer 4 on an empty cell generating device 10 for generating cells and a bus (subscriber line) connected to the empty cell generating device 10, and an empty space sequentially flowing from the upstream. It constitutes an ATM multiplexing system that allocates cells to multiple calls.

Reference numeral 10 denotes an empty cell generator for giving an empty cell generated from the upstream of the bus a terminal ID which can use the empty cell, and 6 is connected to the subscriber line 5 for reading the empty cell ID. It is a media access device that compares and collates with its own ID and controls sending of the buffer 4 according to the result.

[0013]

The empty cell generator 10 adds the ID number to be sent to the cell and sends the cell. On the terminal 3 side, the imported ID number and the ID number it owns are compared and collated,
It is checked whether or not it matches with its own ID, and only when it matches with its own ID, the data accumulated in the buffer 4 is inserted into the empty cell. As described above, according to the present invention, it is possible to provide an access control system for an ATM multiplex bus having good operability.

[0014]

(Embodiment 1) FIG. 2 is a structural block diagram showing an embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals. In the figure, the empty cell generation device 10 has an empty cell 11 and a terminal ID for adding the terminal ID to the empty cell.
A processor (CP that controls the operation of the addition unit 12 and the whole
U) 15. As shown in the figure, the terminal ID is added to the empty cell output from the terminal ID adding unit 12. The processor 15 is for controlling the method of assigning the terminal ID.

Reference numeral 20 denotes a media access unit (MAU), which is composed of a buffer 21 and a comparison unit 21 for comparing the ID of the self terminal from the empty cell sent through the transmission line and the terminal ID. Reference numeral 21 is a comparison unit that receives a signal from the transmission path and compares the input terminal ID with its own terminal ID, and 22 is a buffer for temporarily storing data. Terminal 3
The data from (1) enters the buffer 22, and the used band is notified to the processor 15 in the empty cell generating device 10.

The terminal ID addition unit 12 in the empty cell generator 10 adds a terminal ID designating the terminal 3 that may use the empty cell to each cell. Further, the comparing unit 21 in each media access device 20 compares the input terminal ID with the self-terminal ID, and if it is the self-terminal ID, it is generated from the terminal 3 in the empty cell or the buffer 2
The information accumulated in 2 is added.

By such a method, each media access device 20 detects the terminal ID shown in the empty cell when the transmission request cell is accumulated in the buffer 22,
Only when the ID matches the own terminal ID, it is necessary to control reading one cell from the buffer 22 and overwriting the empty cell, and the configuration of each media access device 20 is greatly simplified. (Embodiment 2) The frequency of occurrence of each terminal ID is made proportional to the required bandwidth for those terminals. That is, the processor 15, which has received the request from the terminal 3, transmits the bandwidth of the transmission medium to the ID in proportion to the requested bandwidth of each terminal.
To be assigned. As a result, cells generated from a certain terminal 3 do not occupy all the empty cells. For example, if the path bandwidth is 150 Mb / s,
25 Mb / s for the first terminal and 50 Mb / s for the second terminal
When the request is made, the ID permitted to be used is given to the first terminal once every three times, and the ID permitted to be used is given to the second terminal twice every three times. As a result, 150 × (1
/ 3) = 50 Mb / s band is guaranteed. (Third Embodiment) In the above-described second embodiment, the occurrence frequency of each terminal ID is determined, but the pattern thereof is not determined.
Therefore, in some cases, there is a possibility that a certain terminal ID will be continuously assigned to the empty cell. By periodically adding the terminal ID to this, the same terminal does not occupy the subscriber line for a long time.

FIG. 3 is an explanatory diagram of the averaging process of each terminal. In the figure, 21 is a requested bandwidth calculation unit, 22 is a pattern determination unit, 23 is a holding output unit, and 24-1 to 24-n are buffers formed by FIFOs provided corresponding to the respective input links, and 26 is A selector, 27 represents an output link.

In the circuit configured as described above, the bandwidth is calculated based on the requested bandwidth of the call corresponding to each input link, and the access pattern is determined so that the frequency is highest corresponding to the bandwidth of each input link. Then, the access pattern is used to read the buffer.

The required bandwidth calculation unit 21 uses each input link 24
The bandwidth requested (or declared) by the users (subscribers) 1 to 24-n is calculated. Next, the pattern determination unit 22
Indicates that the ratio of the frequency of accessing each buffer 25-1 to 25-n is equal to the calculated ratio of the bandwidth of each input link 24-1 to 24-n, and the read access interval of each buffer is as constant as possible. Therefore, the access pattern consisting of the access frequency and the access sequence is determined. The determined access pattern is input to the hold output unit 23.

The hold output unit 23 holds the access pattern and also stores each of the buffers 25-1 to 25-1 in accordance with the pattern.
An output is generated and accessed in any of 25-n to execute a read operation in the corresponding buffer. The ATM cell read from each buffer is output to the output link 27 via the selector 26. The effects of this embodiment are as follows. By evenly reading each buffer, the traffic characteristics (cell discard rate, average waiting time, etc.) of the buffer are improved. Since cells from terminals that generate information in a burst can be periodically sent to the transmission path, the traffic characteristic of the buffer on the side receiving the multiplexed cell stream is improved. A terminal that periodically generates information can store the periodicity. (Embodiment 4) In the above-mentioned embodiment, when a cell is not generated from another terminal, a certain terminal can use all the empty cells, so that the use efficiency of the transmission path is good. However, the user may momentarily use the band higher than the declared value, and conversely the UPC (Usa
ge Parameter Control) is required.

In order to improve this point, the terminal ID and the forbidden ID are generated at the ratio of the required band of each terminal and the band of which the use is prohibited as a free space in consideration of the frequency of the cells to be left free. Moreover, as in the above-described embodiment, in order to eliminate the burst property, each buffer is accessed at equal intervals as much as possible.

FIG. 4 is an explanatory diagram in which each buffer is accessed at equal intervals. The same parts as those in FIG. 3 are designated by the same reference numerals. As shown, this circuit is input via a plurality of input links 24-1 to 24-n. A fixed-length information unit consisting of a pair of transmission information and identification information is output via the selector 26 to a single output link 27.
Buffers 25-1 to 25-n for avoiding a collision at the time of sending the information unit, each input link 24
The concentrator provided for each of -1 to 24-n is provided with the access number determination means 33 and the access interval control means 34.

The access number determining means 33 matches the access number of each of the plurality of buffers 24-1 to 24-n in a certain period with the number of the information units arriving in the buffer within the certain period. The access interval control means 34 uses the plurality of buffers 25 in the fixed period.
The access intervals for -1 to 25-n are made as uniform as possible. The effects of this embodiment are as follows. By reading each buffer evenly, various traffic characteristics (cell discard rate, average waiting time) of the buffer are improved. Cells from terminals that generate information in a burst are periodically sent to the transmission line, and the traffic characteristics of the buffer of the network that receives the multiplexed cell stream are improved. The periodicity can be saved from the terminal that periodically generates information. If this bus is terminated directly on the network side, no bandwidth more than the required bandwidth will be used, so UPC in the network is unnecessary.

For example, if the bandwidth of the bus is 150 Mb / s,
When the terminal 1 requests 25 Mb / s and the terminal 2 requests 50 Mb / s, the ID permitted to be used for the terminal 1 is given once every 6 times, and the ID permitted to be used for the terminal 2 is given twice every 6 times.
That is, the bandwidth of 150 × 1/6 = 25 Mb / s is guaranteed for the terminal 1, and the bandwidth beyond that is never used by the terminal 1.

An example of the even division is, for example, N as a fixed cycle.
Consider t = 20, and consider buffers #i, #j, and #k in which 12 cells, 4 cells, and 3 cells arrive on average. At this time, if the buffer is accessed in the pattern of (iiijikiijikijijiijjk), the access frequency matches the average cell arrival frequency, and the access intervals are relatively uniform.

[0027]

As described above in detail, according to the present invention, it is possible to provide an ATM multi-bus access control system with good operability.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a configuration block diagram showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of averaging processing of each terminal.

FIG. 4 is an explanatory diagram in which access to each buffer is performed at equal intervals.

FIG. 5 is a conceptual diagram of a conventional system.

FIG. 6 is another conceptual diagram of the conventional system.

FIG. 7 is an explanatory diagram of DQDB.

[Explanation of symbols]

 3 terminal 4 buffer 5 subscriber line 6 media access device 10 empty cell generation device

Front page continuation (72) Inventor Ryuichi Takechi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Toshio Somiya 1015, Kamedotachu, Nakahara-ku, Kawasaki, Kanagawa Prefecture

Claims (5)

[Claims] 1. A vacant cell generator (10) for generating vacant ATM cells from an upstream side, and the vacant cell generator (1)
In the ATM multiplexing system, a plurality of terminals (3) are connected via a buffer (4) on a bus connected to (0), and empty cells sequentially flowing from upstream are allocated to a plurality of calls. The generator (10) gives the empty cell generated from the upstream of the bus a terminal ID that can use the empty cell, and is connected to the subscriber line (5) to read the ID of the empty cell.
And an access control system for an ATM multiplex bus, which is provided with a media access device (6) for comparing and collating its own ID and controlling the sending out of the buffer (4) according to the result. 2. A terminal ID adding unit (12) for adding a terminal ID capable of using the empty cell to an empty cell generated from the upstream of the bus in the empty cell generating device (10). Terminal I that compares the terminal ID with its own terminal ID
A D comparison unit (21) is provided on the media access device (6) side, and each terminal (3) checks the terminal ID of each empty cell,
2. The access control system for an ATM multiplex bus according to claim 1, wherein the cell accumulated in the buffer (22) is sent out onto the subscriber line (5) only when the ID of the user is the own ID. 3. When each terminal (3) requests a use band from the empty cell generator (10), the empty cell generator (10) assigns an empty cell terminal ID at a frequency proportional to the requested band. The access control system for an ATM multiplex bus according to claim 1, wherein the access control system is added. 4. The vacant cell generation device (10) is configured to generate vacant cells at a frequency proportional to a requested bandwidth from each terminal (3) and as periodically as possible for each terminal ID. 4. An ATM multiple bus access control system according to claim 3, wherein: 5. The idle cell generation device (10) has a frequency proportional to the required bandwidth of each terminal (3) and the remaining available bandwidth, and each terminal ID and a prohibition ID indicating that no terminal can be used. 2. An access control system for an ATM multiplex bus according to claim 1, wherein both of the above are capable of periodically generating cells.