JP2003224595A - Band control system for line control part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an overflow in an optical subscriber control part in the congestion of an outgoing ATM cell and the increase of a transfer delay time due to fluctuation and also to enable a line control part to control a band at every optical subscriber concerning the band control system of the line control part which is arranged between an ATM switch and the optical subscriber control part for storing a plurality of subscribers. <P>SOLUTION: An out-going band control part of the line control part comprises a plurality of divided buffers for storing cells inputted from a plurality of connections by the unit of subscriber. The band control part also comprises a sorting processing part for identifying the header of the out-going input cell and allocating a corresponding buffer number to a subscriber number, and a reading processing part for reading the cell out to an output transmission line, which is stored in each buffer, by period corresponding to the band allocated by the unit of subscriber. Thus, the cell outputted from the output transmission line is controlled to be supplied to each optical subscriber control part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band control system of a line control unit provided between an optical subscriber control unit accommodating a plurality of subscribers and an ATM switch.

In recent years, an ATM network has been used in which data of various speeds are multiplexed by ATM cells and switching is performed by ATM switches. And ATM
Although it is possible for each subscriber to multiplex and use ATM cells corresponding to a plurality of services, it is difficult for the conventional line control unit to allocate a band to each subscriber, and improvement thereof is desired. ing.

[0003]

2. Description of the Related Art FIG. 6 is a diagram showing a configuration of a conventional example. In the figure, reference numeral 80-1 is an upstream transmission path for transmission from the subscriber 1 to the network side, and the upstream cell a and cell b are transmitted from the subscriber 1 on this transmission path 80-1. Reference numeral 80-2 is an upstream transmission path for transmitting from the subscriber 2 to the network side.
Subscriber 2 transmits uplink cell c and cell d on cell 2. Further, reference numeral 81 is an optical cable for multiplexing the upstream signals of the subscribers 1 and 2 and transmitting the multiplexed signals to the optical subscriber controller.

Reference numeral 82-1 denotes a downlink transmission line to the subscriber 1. In the figure, a cell e for the subscriber 1 is provided on the transmission line 82-1.
A state in which (for service 1) and cell f (for service 2) are transmitted is shown. Reference numeral 82-2 is a downlink transmission line to the subscriber 2. In the figure, a cell g (for service 1) and a cell h (for service 2) for the subscriber 2 are transmitted on the transmission line 82-2. Indicates the status. Reference numeral 83 is an optical cable for transmitting downstream signals to the subscribers 1 and 2, 84 is an optical subscriber control unit accommodating the optical cables 81 and 83, and 85 and 86.
Is a buffer for storing downlink cells and a buffer for storing uplink cells in the optical subscriber control unit 84, 87
Is a line control unit, 88 provided between the optical subscriber control unit 84 and an ATM switch (a device inside the office (not shown)).
AT the upstream cell output from the optical subscriber control unit 84
An upstream band control unit including a buffer for temporarily storing until output to the M switch, 88a and 88b are an input transmission line and an output transmission line of the upstream band control unit 88, and 89 is an ATM.
Downlink band control units 89a and 89b including a buffer for storing downlink cells output from the switch are input transmission lines and output transmission lines of the downlink band control unit 89, respectively.

The transmission lines of the subscribers 1 and 2, the optical cable 81 and the optical subscriber control unit 84 are used as the ATM transmission line side, and the line control unit 87 and the ATM switch (not shown) are used as the ATM switching side. Treated

In the conventional band control system, the cells a and b on the upstream transmission line 80-1 of the subscriber 1 are input cells from ATM virtual connections (VPI / VCI) corresponding to different services (applications). In the optical cable 81, input cells c and d from different ATM virtual connections on the upstream transmission line 80-2 of the other subscriber 2
Is supplied to the optical subscriber control unit 84, and the buffer 8
5 are sequentially stored. Each cell read from the buffer 85 of the optical subscriber control unit 84 is stored in the upstream band control unit 88 through the input transmission line 88a of the line control unit 87. A plurality (88-0 to 88-n) are provided separately (by service, that is, by band), and the VPI / VCI of the cell is identified and stored in the buffer corresponding to the VCI. In the example of FIG. 6, the buffer 88-0 stores cells corresponding to the service type transmitted from the subscriber 1, and the buffer 88-n stores cells corresponding to the service type transmitted from the subscriber 2. When reading cells from the plurality of buffers 88-0 to 88-n to the output transmission path 88b, the reading cycle is controlled by the priority according to the service type (bandwidth) assigned to the VCI of each buffer.

The cell output from the output transmission path 88b is A
The cells that are input to the TM switch (not shown) and switched and output from the ATM switch are input transmission lines 8
9a is input to the downstream band control unit 89, and one of them is input.
The data is output to the output transmission line 89b in the order input from the one buffer. The cell of the output transmission line 89b is the optical subscriber control unit 8
No. 4 is input to the buffer 86, and the cells for the subscriber 1 or the subscriber 2 are read from the buffer 86 in the order in which they are input to the optical cable 83, and priority control by VCI is not performed. In addition, from the optical subscriber control unit 84 to the optical cable 83
The routing information is added to the ATM cell data for each subscriber, the band is allocated to each optical subscriber, and the cell data is transferred to the optical subscriber. In the example of FIG. 6, a cell e (for service 1) is provided on the downlink transmission path 82-1 for the subscriber 1.
Two types of cells, cell f (for service 2), are transmitted, and two types of cells, cell g (for service 1) and cell h (for service 2), are transmitted to the downlink transmission path 82-2 for the subscriber 2. To be done.

[0008]

In the prior art, since the downlink ATM cell data of the line control unit is accumulated in one buffer of the downlink band control unit, the downlink AT
When M cells are congested, cells are continuously input to the optical subscriber control unit at a speed equal to or higher than a certain speed, so that there is a problem that the downstream buffer of the optical subscriber control unit overflows.
Moreover, since ATM cell data is transferred after the routing information conversion for each optical subscriber, the ATM cell arrives early,
There has been a problem that the transfer delay time increases due to "fluctuation" such as arriving late.

Further, since it is not possible to set the band for each optical subscriber in the line control unit, when it is used as an access system network (a network on the subscriber side including an optical cable and an optical subscriber control unit), the optical subscriber unit is used. There was a problem that the bandwidth could not be effectively used for multiple services.

The present invention prevents overflow in the optical subscriber control unit at the time of congestion of downlink ATM cells and increase in transfer delay time due to fluctuation, and enables band control for each optical subscriber of the line control unit. It is an object to provide an ATM interface band control system.

[0011]

FIG. 1 is a diagram showing the principle configuration of the present invention. FIG. 1 shows a configuration of a downlink band control unit mainly in a line control unit that controls a downlink cell from an ATM station (or a network side provided with a switch) toward a subscriber. In the figure, 1 is a line control unit, 2 is an upstream band control unit, 3 is a downstream band control unit, 3a is an input transmission line from an ATM switch to the downstream band control unit 3, and 3b is a downstream band control unit 3 From optical transmission line to optical subscriber control unit, 4
Is a distribution processing unit for distributing the input cells to the buffer corresponding to the subscriber, and 5 is a code 5-0 provided corresponding to the subscriber.
A buffer containing a plurality of individual buffers represented by ~ 5-n,
Reference numeral 6 is a read processing unit for reading from the cells of the plurality of buffers 5-0 to 5-n in the band allocated (set) corresponding to the subscriber, and 7 is an optical subscriber control unit. In addition,
The upstream band control unit 2 is the same as the conventional one, and the inside thereof is omitted in the drawing.

A plurality of numbers are assigned to the subscribers in the downlink band controller 3 of FIG. 1, and the cells output from the ATM switch and input to the input transmission line 3a are added to the downlink band controller 3. In the distribution processing unit 4 corresponding to each person, the VPI / VCI of the cell header is identified, and each VPI / VCI is identified in advance.
By referring to a table (not shown in FIG. 1) in which buffer numbers assigned to VCI and optical subscriber numbers are set, a buffer number corresponding to the optical subscriber number of the cell destination is detected and input. The allocated cell is allocated to the buffer. At this time, cells corresponding to a plurality of services (or connections) may be input to the same subscriber number, but they are sequentially assigned to the same buffer. The read processing unit 6 holds a band (readout cycle) set in advance for each subscriber number according to a declaration or the like, and sequentially stores the buffers 5-0 to 5-n corresponding to the subscriber numbers. Read processing is performed. In that case, when the read cycle corresponding to the band of each subscriber number is reached, the cells of the buffer are read out, output to the output transmission line 3b, and input to the optical subscriber control unit 7.

As described above, the downlink band control unit 3 stores the data in the buffers 5-0 to 5-n corresponding to the subscribers to perform the scheduling control corresponding to the band, and thereby the AT
It is possible to reduce the transfer delay time due to the fluctuation of ATM cell data such that M cells arrive early or late.

Further, the cell data input from a plurality of services (connections) can be managed by allocating a buffer for each optical subscriber in the downstream band control unit 3 of the line control unit 1. When a plurality of services (a plurality of connections) are accommodated for each, it is possible to use the maximum bandwidth within the bandwidth allocated to each subscriber for each connection (service).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the configuration of an embodiment of a downlink band control unit. In the figure, 3, 3a, 3b, 4,5, 5-0
˜5-n, 6 correspond to each part of the same reference numeral in FIG.
Is a downstream band control unit, 3a is an input transmission line, 3b is an output transmission line, 4 is a distribution processing unit, 5 is a buffer, and 5-0 to 5-5.
-N is an individual buffer corresponding to a subscriber, and 6 is a read processing unit.

The distribution processing unit 4 has VPI and VC in advance.
I, and tables 4-0 to 4-n in which buffer numbers assigned to subscriber numbers are set (V
The PI and VCI are included in the ATM header (the subscriber number uses a preset number), but the read processing unit 6 assigns it to the subscribers corresponding to the divided buffers. Buffer 0 scheduler 6-0 to buffer n scheduler 6-n, which are tables for setting the allocated bandwidth, are set.

The process of writing the input cell to the buffer and the process of reading from the buffer in the configuration shown in FIG. 2 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a processing flow of the input cell, which is executed by the distribution processing unit 4 of FIG. At first,
Control constants for distribution processing are set in the table (4-0 to 4-n in FIG. 2). Set VPI (S in Figure 3
1) Next, the VCI is set (at step S2), the buffer number is further set (at step S3), and then the optical subscriber number is set (at step S4). Subsequently, it is determined whether or not there is a cell input (S5 in FIG. 3), and if there is, a VPI included in the header of the cell.
-Identify the VCI and determine whether the VPI, the buffer number corresponding to the VCI, and the optical subscriber number have already been set (S6).
If it is set, the input cell is written according to the buffer number (at step S7).

FIG. 4 is a processing flow of the output cell, which is executed by the read processing unit 6 of FIG. At first,
The scheduler corresponding to the buffer allocated to each subscriber is set, and each scheduler 6-0 to 6-0 is set.
The reading cycle corresponding to each band is set to -n. At that time, there is a limit that the total of all the buffers is 1/1, and specifically, for example, when the buffer 0 = 1/2 is set, it cannot be set larger than the buffer n = 1/2.

Then, the reading of one buffer is started (S2 in FIG. 4), and it is determined whether or not there is a cell input (cells already stored) in the buffer (S3). If there is a cell input, it is determined whether the read cycle of the buffer has been reached (S4 in FIG. 4).
The cell is read out and output (at step S5). Next, the read buffer number is updated (S6 in FIG. 4), the process returns to S3 and the same processing is repeated.

FIG. 5 shows an operation example according to the present invention. In the figure,
Reference numerals 1, 2, 3, 3a, 3b, 5-0 to 5-n are the same as those in FIG. However, although the distribution processing unit 4 and the read processing unit 6 in the downlink band control unit 3 are not shown, they have the same configuration as that of FIG. Also,
2a and 2b are input transmission lines and output transmission lines to the upstream band control unit 2, 7 is an optical subscriber control unit, 7a and 7b are upstream buffers and downstream buffers of the optical subscriber control unit 7, and 8 is a subscriber a. And an optical cable for multiplexing the upstream signal of the subscriber b and transmitting it to the optical subscriber controller, 8a and 8b are upstream transmission lines of the subscriber a and the subscriber b, and 9 is to the subscriber a and the subscriber b. The optical cables 9a and 9b for transmitting downstream signals of the subscriber a
And the downstream transmission line of the subscriber b.

The operation of bandwidth control in the down direction in the configuration of FIG. 5 will be described. On the input transmission line 3a of the downstream band control unit 3, cells a1, a2, a3 destined to the subscriber a and cells b1, b2, b3 destined for the subscriber b are input. However, the cell a1 has a header with a path number = 1, a channel number = 1, and an optical subscriber number =
VPI of ATM cell header set as a (by pass number, channel number (and optical subscriber number))
Form VCI). A preset optical subscriber number is assigned on the input transmission line. Cell a2
Are set as path number = 1, channel number = 2, optical subscriber number = a, and are similarly set for cell a3. The cell b1 has a path number = 1 and a channel number =
1, optical subscriber number = b, cell b2 is set as path number = 1, channel number = 2, optical subscriber number = b, and cell b3 is similarly set.

When these cells are input to the downstream band control unit 3, the distribution processing unit 4 in FIG. 2 makes each cell a buffer corresponding to the optical subscriber number by the processing flow of the input cells shown in FIG. Written. In the example of Figure 5,
The cell with the optical subscriber number = a is written in the buffer 5-0, and the cell with the optical subscriber number = b is written in the buffer 5-n. The cells written in the buffers 5-0 to 5-n are read by the read processing unit 6 of FIG. 2 according to the processing flow of the output cells of FIG. In the example of FIG. 5, the scheduler 6-0 (corresponding to the buffer 5-0) to the scheduler 6-n (buffer 5-
(corresponding to n), a read cycle corresponding to each band is set. In this example, for the optical subscriber number = a of the scheduler 6-0, 1 of the entire band of the output transmission line 3b is set.
/ 4 is allocated, and 1/2 of the entire band is allocated to the optical subscriber number = b of the scheduler 6-n. When the output cells are processed according to the band, the cells (represented by □, ■, and □) stored in the buffer 5-0 are sequentially read one by one in the four read cycles, and the buffer 5 is read. The cells (represented by ◯, ●, ◯) stored in −n are read out sequentially in the four read cycles (or one in the two read cycles), and there is no cell to be read. And "empty" cells are set, and cells are output on the output transmission line 3b as shown in FIG. When these cells are input to the optical subscriber control unit 7, they are output from the downstream buffer 7b to the optical cable 9 and sent to the transmission line 9a of the subscriber a and the transmission line 9b of the subscriber b.

(Supplementary Note 1) In a band control system of a line control unit provided between an optical subscriber control unit accommodating a plurality of subscribers and an ATM switch, a plurality of connections are provided to a downlink band control unit of the line control unit. A plurality of divided buffers for storing the cells input from each of the subscribers in units of subscribers, and a distribution processing unit that identifies a header for the downlink input cells and assigns a buffer number corresponding to the subscriber number, A read processing unit for reading cells stored in each buffer to an output transmission line at a cycle corresponding to a band assigned to each subscriber, and controlling each optical subscriber of the cells output from the output transmission line A bandwidth control method for the line control unit, which is characterized in that it is supplied to the control unit.

(Supplementary Note 2) In Supplementary Note 1, the distribution processing unit is provided with a table in which an optical subscriber number and a buffer number are set in advance in the VPI and VCI of the cell. .

(Supplementary Note 3) In Supplementary Note 1, the read processing unit sets a read cycle corresponding to a band allocated to each subscriber in the entire read cycle in advance for each buffer. A band control method of a line control unit, wherein cells of each buffer are read based on a read cycle set in a table.

(Supplementary Note 4) In Supplementary Note 1, when a plurality of connections are stored for each optical subscriber in the plurality of buffers, the maximum bandwidth within the bandwidth allocated to each subscriber for each connection is used. Band control method of the line control unit characterized by.

[0028]

According to the present invention, without providing a complicated circuit for controlling the transfer rate of ATM cell data,
It can be stored in a buffer corresponding to the optical subscriber, and by reading from the buffer and transferring in a band determined in advance by the service, A in the optical subscriber control unit
It is possible to solve the problems of TM cell data contention and buffer overflow, and prevent fluctuations when converting routing information for each optical subscriber. Furthermore, it becomes possible to transfer ATM cell data to the optical subscriber at a transfer rate in accordance with the band determined by the service.

Further, when a plurality of services are carried out by one optical subscriber, the bandwidth for all services can be used even if all services are not used, and efficient services can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a configuration of an embodiment of a downlink band control unit.

FIG. 3 is a diagram showing a processing flow of an input cell.

FIG. 4 is a diagram showing a processing flow of an output cell.

FIG. 5 is a diagram showing an operation example according to the present invention.

FIG. 6 is a diagram showing a configuration of a conventional example.

[Explanation of symbols]

1 line control unit 2 Uplink bandwidth controller 3 Downlink bandwidth controller 3a Input transmission line 3b output transmission line 4 Sorting processing unit 5 buffers 5-0-5-n Individual buffers for subscribers 6 Read processing unit 7 Optical subscriber control unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuharu Tsunoda             3-9-18 Shin-Yokohama, Kohoku Ward, Yokohama City, Kanagawa Prefecture             Fujitsu Communication System             Within Co., Ltd. (72) Inventor Kazuhiro Matsumoto             3-9-18 Shin-Yokohama, Kohoku Ward, Yokohama City, Kanagawa Prefecture             Fujitsu Communication System             Within Co., Ltd. (72) Inventor Soichi Kato             3-9-18 Shin-Yokohama, Kohoku Ward, Yokohama City, Kanagawa Prefecture             Fujitsu Communication System             Within Co., Ltd. (72) Inventor Yukihiro Doi             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Osamu Sawada             3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Tohnichi             Inside Telegraph and Telephone Corporation F term (reference) 5K030 HA10 HB14 JL03 JL08 KA03                       LC02 LC09

Claims (3)

[Claims] 1. In a band control system of a line control unit provided between an optical subscriber control unit accommodating a plurality of subscribers and an ATM switch, a downlink band control unit of the line control unit is input from a plurality of connections. A plurality of divided buffers for storing cells for each subscriber, a distribution processing unit that identifies a header for the downlink input cell and assigns a buffer number corresponding to the subscriber number, and each of the buffers. And a read-out processing unit for reading the cells stored in the output transmission line in a cycle corresponding to the band allocated to each subscriber unit, and transmitting the cells output from the output transmission line to each optical subscriber control unit. A bandwidth control method for a line control unit characterized by supplying. 2. The bandwidth control method of the line control unit according to claim 1, wherein the distribution processing unit includes a table in which an optical subscriber number and a buffer number are set in advance in VPI and VCI of a cell. 3. The read processing unit according to claim 1, wherein a read cycle corresponding to a band allocated to each subscriber in the entire read cycle is set in advance for each buffer, A band control method for a line control unit, wherein cells of each buffer are read based on a read cycle set in step 1.