JP3507688B2 - Round robin control apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is used in an ATM communication system. The present invention relates to round robin control in connection management in an ATM switch or ATM transmission device. The invention is particularly suitable for controlling ATM switching devices,
Connection can be searched easily and the minimum bandwidth (MC
R Minimum Cell Rate) guarantee and maximum bandwidth (PCR
Peak CellRate) A scheduling method that can be restricted. Further, the present invention relates to a scheduling method in which the minimum bandwidth setting and the maximum bandwidth setting of a connection can be changed without affecting other connections.

[0002]

2. Description of the Related Art In resource control for ATM connection management, a weighted round robin (weighted roun) has been conventionally used as a scheduling method for guaranteeing a minimum bandwidth.
d Robin) method is used. In this weighted round robin method, the minimum bandwidth can be guaranteed according to the weight ratio of each connection, and the surplus bandwidth can be distributed according to the weight ratio of each connection. In addition, UBR (Unspecified Bit Rate) +
The (or GFR Guaranteed Frame Rate) class includes a service class that guarantees the minimum bandwidth and evenly distributes the surplus bandwidth in each connection. Both are defined as best-effort services, and the minimum bandwidth is guaranteed for the user.

[0003]

The first problem of the prior art is that network congestion occurs when enormous amounts of data that are not expected by the user are transferred by only setting the minimum bandwidth for guaranteeing the minimum bandwidth. Is caused.
This is because the setting that limits the maximum bandwidth and the scheduling method that limits the maximum bandwidth are not implemented.

The second problem is that the weighted round robin method cannot realize maximum bandwidth limitation. In the weighted round robin method, the minimum bandwidth can be guaranteed according to the weight ratio of each connection, but the surplus bandwidth is distributed according to the weight ratio of each connection.

An object of the present invention is to provide a method and an apparatus for reading a buffer of a buffer such as an ATM switch by a round robin control method in which not only the minimum bandwidth is guaranteed but also the maximum bandwidth is limited. Another object of the present invention is associative memory (CAM Content Addressa).
It is to provide a scheduling method by a round robin control method that can easily perform connection search by using ble Memories). Another object of the present invention is to provide a scheduling method by round robin control that can change the setting of the minimum bandwidth and the maximum bandwidth of a connection by using an associative memory without affecting other connections. .

[0006]

The first aspect of the present invention is to:
In a control device that performs connection control with an ATM switch or an ATM transmission device, the number of minimum band cells that can be transmitted to the address corresponding to the connection number in the associative memory, and the number of cells obtained by subtracting the minimum band cell number from the maximum band cell and buffer A connection search table in which information on the presence / absence of cells within the connection search table is set, the connection number is searched from the presence / absence of the minimum bandwidth cells in the connection search table and the presence / absence of cells in the buffer, and the ATM cell of the corresponding connection number is searched. When there is no applicable connection number, the connection number is searched from the presence or absence of the number of cells obtained by subtracting the minimum bandwidth cell number from the maximum bandwidth cells and the presence or absence of cells in the buffer, and the connection number of the relevant connection number AT
It is characterized by comprising means for transmitting M cells.

A second aspect of the present invention relates to a scheduling method by round robin control in connection control, which is the minimum band cell number and maximum band cell number that can be transmitted to an address corresponding to a connection number on an associative memory. The number of cells obtained by subtracting the minimum bandwidth cell number from the, the connection search table that stores the information of the presence or absence of cells in the buffer is set, the presence or absence of the minimum bandwidth cells of the connection search table and the presence or absence of cells in the buffer, To find the connection number, send out the ATM cell with the corresponding connection number, and if there is no corresponding connection number, check whether there is a cell number obtained by subtracting the minimum bandwidth cell number from the maximum bandwidth cell number and the number of cells in the buffer. The connection number is searched for based on the presence / absence, and the corresponding connection number A
It is characterized by transmitting TM cells.

In the scheduling by the round robin control according to the present invention, a connection search table in which the number of minimum band cells and the number of (maximum band-minimum band) cells are set for each connection using the associative memory is constructed. The minimum bandwidth guarantee and the maximum bandwidth limitation can be performed at the same time by searching for a connection that can be transmitted according to the minimum bandwidth cell number and the (maximum bandwidth-minimum bandwidth) cell number in this connection search table. Also, as a result of the connection search, when there is a corresponding connection, the next connection search start is set after the corresponding connection, so that the ATM cells of each connection are sent in a fair manner according to the set minimum band and maximum band. can do. Furthermore, by implementing the connection search table in an associative memory, it becomes possible to change the minimum bandwidth and maximum bandwidth settings of a connection without affecting other connections.

In addition to the connection lookup table, the minimum number of cells that can be sent to a memory in which normal data can be written / read, (maximum bandwidth-minimum bandwidth)
A connection transmission cell number table storing information on the number of cells is constructed, and the connection search table has a flag of the minimum bandwidth cell number of this connection transmission cell number table, a flag of the (maximum bandwidth-minimum bandwidth) cell number, Information about whether or not there is a cell in the buffer is set, and the corresponding connection number is searched depending on whether there is a minimum bandwidth cell that can be sent, (maximum bandwidth-minimum bandwidth) cell, and whether there is a cell in the buffer. By controlling, the data width of the associative memory that constructs the connection search table can be reduced, and the system can be constructed inexpensively.

[0010]

DETAILED DESCRIPTION OF THE INVENTION An example of an embodiment of the present invention will be described below with reference to the drawings.

Guaranteed minimum bandwidth (hereinafter referred to as MCR),
A connection search table of a round robin control method that realizes maximum bandwidth (hereinafter referred to as PCR) limitation is constructed in an associative memory. As the contents of this connection search table, the address corresponds to the connection number, and as the data, A to be sent in order to guarantee the minimum bandwidth.
The number of MCR cells as the number of TM cells, the number of (PCR-MCR) cells as the number of ATM cells that can be transmitted at MCR or more and less than or equal to PCR to limit the maximum bandwidth, and A of each connection
Buffer state information indicating whether or not TM cells exist in the buffer, an initial value of the number of MCR cells, and an initial value of the number of (PCR-MCR) cells are stored. The buffer status is
“1” is set when there is a cell in the buffer, and “0” is set when there is no cell in the buffer. The number of MCR cells, (PCR-
The MCR) number of cells is a numerical value obtained by converting the minimum bandwidth and the maximum bandwidth-minimum bandwidth into the number of ATM cells transmitted within an arbitrary time unit. Here, the associative memory is capable of inputting search data in addition to normal writing / reading and outputting the presence or absence of the same or similar data, other data of the word to which the data belongs, and the address and the like. Refers to memory.

That is, in the control unit for controlling the connection of the ATM switch or the ATM transmission device, the minimum band cell number that can be sent to the address corresponding to the connection number on the associative memory and the minimum band cell number are subtracted from the minimum band cell number. It has a connection lookup table in which information on the number of cells and the presence / absence of cells in the buffer is set, and the connection number is retrieved from the presence / absence of the minimum bandwidth cells in this connection lookup table and the presence / absence of cells in the buffer. When the ATM cell with the connection number is transmitted and there is no corresponding connection number, the connection number is searched from the presence or absence of the number of cells obtained by subtracting the minimum bandwidth cell number from the maximum bandwidth cell number and the presence or absence of cells in the buffer, It is provided with means for transmitting the ATM cell of the corresponding connection number.

The operation of the connection search table shown in FIG. 1 will be described below with reference to FIGS.

At the cycle of reading ATM cells from the buffer (step A1), the search start connection is acquired from the register (step A2), and after the search start connection, MCR guarantee (the number of MCR cells> 0 and the buffer state = 1) is obtained. The connection is searched (step A3).
Determine the MCR guaranteed connection search result (Step A
4) If there is a corresponding connection, write a value obtained by subtracting the number of MCR cells by -1 (step A5), and send out the ATM cell of the corresponding connection (step A1).
2). If there is no corresponding connection in the connection search of MCR guarantee (the number of MCR cells> 0 and the buffer state = 1) in step A4, the next PCR restriction ((PC
(R-MCR) Connection search is performed with the number of cells> 0 and buffer state = 1 (step A6). The result of the PCR-restricted connection search is determined (step A7), and if there is a corresponding connection, a value obtained by subtracting (PCR-MCR) cell number by -1 is written (step A8), and the ATM cell of the corresponding connection is transmitted. Do (Step A
12). If there is no applicable connection, PCR
Recognize whether or not the connection is restricted (Step A
9) If the connection has no PCR restriction, a connection search with buffer status = 1 is performed (step A1).
0). It is determined whether or not the search result is a connection without PCR restriction (step A11), and if there is a corresponding connection, the ATM cell of the corresponding connection is transmitted (step A12). If the search result is a connection with PCR restriction, or if there is no connection with PCR restriction but the buffer status = 1, there is no empty cell (step A1).
3).

At step A12, the AT of the corresponding connection
After sending M cells, the cell state in the buffer is confirmed (step A14), the buffer state is set to 1 if there is a cell in the buffer (step A15), and if there is no cell in the buffer. The buffer state is set to 0 (step A16). When there is a corresponding connection and the ATM cell of the corresponding connection is sent out, a search start register is prepared in order to start the next connection search from the next connection of the corresponding connection.
The relevant connection is stored in the search start register (step A17). Also, the number of MCR cells of all connections is monitored (step A18), and it is determined whether the number of MCR cells is 0 (step A19). If the number of MCR cells of the connection is 0, MCR is determined. The number of cells and the number of (PCR-MCR) cells are initialized (step A20).

Further, a specific example of the connection search table will be described with reference to FIG.

FIG. 2 is an example of a search table for three connections A, B, and C. When the throughput read from the buffer is 150 Mbs,
The number of cells that can be transmitted to guarantee 150 Mbps in a certain arbitrary unit time is 150 cells. It is assumed that the MCR / PCR band settings for three connections input to this buffer are as follows. Connection A: MCR =
5 Mbps, PCR = 10 Mbps, connection B:
MCR = 10 Mbps, PCR = 25 Mbps, Connection C: MCR = 25 Mbps, PCR = 50 Mbps
Becomes Since 150 Mbps is guaranteed if 150 cells are sent out per unit time, MCR / PCR of each connection
Is converted to the number of cells, connection A is 5 cells / 10
The cell and connection B are 10 cells / 25 cells, and the connection C is 25 cells / 50 cells. Here, since the parameter set in the connection search table is not PCR but the number of cells that can be sent up to PCR at MCR or more, the number of cells of MCR / (PCR-MCR) of each connection is shown in the search table of FIG. As shown, the connection A has five MCR cells, five (PCR-MCR) cells, and the connection B has ten MCR cells and (PCR-MCR) cells.
The number of MCR cells is 15, and the number of connections C is 25 MCR cells and 25 (PCR-MCR) cells, and the connection search table of FIG. 3 is constructed.

As the operation of the connection search table,
It is decremented by 1 every time the ATM cell of the corresponding connection is transmitted. Whenever the number of MCR cells becomes 0 and then the ATM cell of the corresponding connection is transmitted, (PCR
-MCR) Subtract the number of cells by one. (PCR-M
CR) When the number of cells becomes 0, A of the relevant connection
No TM cells are sent out. However, for connections that do not have PCR restrictions, monitor only the buffer status.
Send TM cells. MCR of all connections
When the number of cells becomes 0, the number of MCR cells and (PCR-M
(CR) The number of cells is returned to the initial value (step A20).

Next, another embodiment of the present invention will be described with reference to FIGS. 5, 6, 7 and 8.

FIG. 5 shows a connection search cable (a) and a connection transmission cell number table (b). In this embodiment, the connection search table is constructed by an associative memory, and the connection transmission cell number table is constructed by a normal writable / readable memory. As the contents of the connection search table, if the address corresponds to the connection number and the number of MCR cells to be transmitted to guarantee MCR is 0 or more in the connection transmission cell number table, the MCR flag that is set, Similarly, in the connection transmission cell number table, a PCR flag that is set when the number of cells (PCR-MCR) is 0 or more in order to limit PCR, and a buffer state indicating whether or not the ATM cell of each connection exists in the buffer is set. is there.

In the connection transmission cell number table, the address corresponds to the connection number, and the data includes the MCR cell number, the (PCR-MCR) cell number, and the MCR.
An initial cell number value and a (PCR-MCR) initial cell number value are provided.

The number of MCR cells and the number of (PCR-MCR) cells indicate the number of cells that can be transmitted within an arbitrary time. The settings of MCR and PCR are arbitrary, and when setting a large band, a large-scale associative memory with a wide data width is required. So, in the connection search table,
MC of the connection transmission cell number table prepared as a separate table by preparing the MCR flag and the PCR flag
When the number of R cells and the number of (PCR-MCR) cells are 0 or more, flags are set respectively, and when they become 0, the number of flags is cleared. Therefore, the MCR flag, P
One bit may be prepared for each CR flag. In the embodiment using the search cable shown in FIG. 5, M
When setting a large number of CR cells and (PCR-MCR) cells, a connection transmission cell number table using a normal writable / readable memory is prepared as a separate table, and the MCR flag and the PCR flag are prepared. By providing, there is an advantage that the connection lookup table can be realized by a small-scale associative memory having a narrow data width.

FIGS. 6, 7 and 8 show operation flows using the connection search table shown in FIG. When the number of MCR cells and the number of PCR cells are stored in the connection search tables of FIGS. 3 and 4, for example, MCR guarantee is determined under the condition that the MCR flag of the connection search table is 1 and the buffer state is 1 (step A103, A104),
When there is a corresponding connection number, the number of MCR cells in the column of the number of MCR cells in the connection transmission cell number table is written by subtracting -1 (step A105).
It is determined whether the number of cells becomes 0, the flag of the connection search table is processed, and then the corresponding connection cell is transmitted (steps A107 to 109, A118).
In this way, the difference is that the processing between the connection search table and the connection transmission cell number table is included,
The basic processing operation is common.

In the embodiment shown in FIGS. 5 to 8, the data width of the associative memory which is the connection search table provided in the round robin control method for MCR guarantee and PCR restriction can be reduced.

[0025]

The present invention having the above-described structure has the following effects.

First, there is an effect that not only MCR guarantee but also scheduling including PCR restriction can be performed. This is because not only the number of MCR cells but also the number of (PCR-MCR) cells are prepared in the connection search table.

Next, the settings of MCR and PCR of a connection can be changed without affecting other connections. This is because the associative memory is used as the connection search table. Since the associative memory can write / read data like the communication memory, by changing the MCR cell number initial value and the PCR cell number initial value for each connection, that is, for each address, the ATM of each connection can be changed. Cell transmission is MCR or PCR
Therefore, the data can be transmitted fairly.

Furthermore, the ATM cells of each connection can be transmitted fairly according to MCR or PCR. As a result of the connection search, if there is a corresponding connection, set the corresponding connection in the register to start the next connection search, and set the search start address of the next associative memory after the previous corresponding connection. This is because you can

Further, the MCR flag and the PCR flag are set in the connection search table constituted by the associative memory, and the MCR cell number, PCR-MCR cell number, MCR cell number initial value, PCR-MCR cell number initial value of each connection are set. Is set in the connection transmission cell registration table composed of a normal memory, the data width of the associative memory can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a table according to a first embodiment of this invention.

FIG. 2 is a diagram showing a specific example of a connection search table.

FIG. 3 is a flowchart illustrating the operation of the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating the operation of the first embodiment of the present invention.

FIG. 5 is a diagram showing a table according to a second embodiment of this invention.

FIG. 6 is a flowchart illustrating the operation of the second embodiment of the present invention.

FIG. 7 is a flowchart illustrating the operation of the second embodiment of the present invention.

FIG. 8 is a flowchart illustrating the operation of the second embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shunsuke Tsutsumi 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-11-88343 (JP, A) Electronic IEICE Technical Research Report SSE 96-186 IEICE Technical Research Report SSE 97-166 IEICE Technical Research Report SSE 97-92 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12 / 56

Claims (9)

(57) [Claims] 1. The minimum number of cells that can be transmitted, the number of cells obtained by subtracting the number of minimum bandwidth cells from the number of maximum bandwidth cells, and information about the presence or absence of cells in the buffer are set to the address corresponding to the connection number on the associative memory. The connection search table is provided, and the connection number is searched based on the presence / absence of the minimum bandwidth cells in the connection lookup table and the presence / absence of cells in the buffer.
The ATM cell having the connection number corresponding to the search condition is transmitted, and the minimum band cell number is present and the cell in the buffer is present.
If there is no connection number that matches the search conditions ,
The connection number is searched based on the presence / absence of the number of cells obtained by subtracting the minimum bandwidth cells from the maximum bandwidth cells and the presence / absence of cells in the buffer, and the connection number is searched by subtracting the minimum bandwidth cells from the maximum bandwidth cells.
A round robin control device comprising means for transmitting an ATM cell having a connection number corresponding to a search condition in which the number of packets is present and the cells in the buffer are present . 2. A connection lookup table constructed in an associative memory, and the connection lookup table refers to the connection lookup table so that data can be written and read, and the minimum number of bandwidth cells and the maximum number of cells that can be sent to an address corresponding to the connection number. The connection transmission cell number table storing information including the information of the cell number obtained by subtracting the minimum band cell number from the band cell number is provided, and the connection search table has an address corresponding to a connection number at the connection transmission cell number. A flag indicating the state of the number of lowest band cells of the table and a flag indicating the state of the number of cells obtained by subtracting the number of lowest band cells from the number of highest band cells, the information of the presence or absence of cells in the buffer is set, the lowest of the connection search table A flag indicating the number of band cells and the presence or absence of cells in the buffer Find the connection number, minimum number of band cells is within the buffer Yu
AT with connection number corresponding to search condition with cell
Send M cells and have the minimum number of cells in the buffer
Of when the cell is no connection number corresponding to the search condition of the chromatic retrieves the connection number from the presence or absence of cells in the minimum bandwidth the number of cells the presence and the buffer number of cells minus the maximum band number of cells, the maximum Number of band cells to lowest band cell
Search criteria with the number of cells minus the number of cells in the buffer
Round robin control apparatus characterized by comprising means for transmitting ATM cell connection number corresponding to matter. 3. The associative memory stores the minimum band cell number that can be transmitted to the address corresponding to the connection number, the number of cells obtained by subtracting the minimum band cell number from the maximum band cell number, and information on the presence or absence of cells in the buffer. The connection search table is set, and the connection number is searched from the presence / absence of the minimum bandwidth cell number in the connection lookup table and the presence / absence of cells in the buffer, and the minimum bandwidth cell number is detected and the cell in the buffer is detected.
Sending the ATM cell connection number corresponding to search criteria, the search cells in the buffer of the chromatic number the minimum bandwidth cells Yu
If there is no connection number that meets the conditions, the connection number is searched based on the presence or absence of the number of cells obtained by subtracting the minimum bandwidth cell number from the maximum bandwidth cell number and the presence or absence of cells in the buffer, and the maximum bandwidth cell number Number of cells minus number of cells
And a cell in the buffer is present, an ATM cell having a connection number corresponding to a search condition is transmitted, and a scheduling method by round robin control. 4. In addition to the connection lookup table built in the associative memory, a minimum number of band cells that can be sent to an address corresponding to a connection number, and a minimum number of maximum band cells are stored in a memory in which data can be written and read. A connection transmission cell number table storing information on the cell number obtained by subtracting the number of band cells is provided, and at the address corresponding to the connection number of the connection search table, the minimum bandwidth cell number of the corresponding connection of the connection transmission cell number table A flag indicating the state, a flag indicating the state of the number of cells obtained by subtracting the minimum number of cells from the maximum number of bandwidth cells, stores the information of the presence or absence of cells in the buffer, the presence or absence of the minimum bandwidth cells of the connection search table and the buffer Find the connection number from the presence or absence of cells of the inner, the number of minimum bandwidth cell Test cell in the buffer Yu in
Sending the ATM cell connection number corresponding to search criteria, the search cells in the buffer of the chromatic number the minimum bandwidth cells Yu
If there is no connection number that meets the conditions, the connection number is searched based on the presence or absence of the number of cells obtained by subtracting the minimum bandwidth cell number from the maximum bandwidth cell number and the presence or absence of cells in the buffer, and the maximum bandwidth cell number Number of cells minus number of cells
And a cell in the buffer is present, an ATM cell having a connection number corresponding to a search condition is transmitted, and a scheduling method by round robin control. 5. A search of the connection search table, showing that there is a minimum number of bandwidth cells and there are cells in the buffer.
Condition or maximum bandwidth cells minus minimum bandwidth cells
The number of cells is "Yes" and the cells in the buffer are "Yes" .
5. The scheduling method by round robin control according to claim 3, wherein the next connection search start is set after the corresponding connection when there is a connection number. 6. A connection search table search result,
Search condition with minimum bandwidth cells and buffer cells
There is a connection number corresponding to, and an ATM cell is sent.
If so, the minimum number of bandwidth cells in the connection search table
Write the value obtained by subtracting 1 from the connection search table
As a result of searching for
If the number of cells subtracted is present and the cells in the buffer are present
There is a corresponding connection number, and an ATM cell is sent out.
The maximum number of cells in the connection search table
Write the value obtained by subtracting 1 from the number of cells obtained by subtracting the number of lowest band cells from
By the round robin control according to claim 3 or 4,
Scheduling method. 7. All the connection search table
When the minimum number of cells in the connection becomes 0, the maximum
Number of low-band cells and maximum-band cells to minimum-band cells
The round according to claim 6, wherein the number of cells obtained by subtracting is returned to the initial value.
Scheduling method by Robin control. 8. A connection search table search result,
Search condition with minimum bandwidth cells and buffer cells
There is a connection number corresponding to, and an ATM cell is sent.
If so, the minimum number of bandwidth cells in the connection search table
Write the value obtained by subtracting 1 from the connection search table
As a result of searching for
If the number of cells subtracted is present and the cells in the buffer are present
There is a corresponding connection number, and an ATM cell is sent out.
The maximum number of cells in the connection search table
Write the value obtained by subtracting 1 from the number of cells obtained by subtracting the number of lowest band cells from
Round robin according to claim 1 or 2, including means for inserting.
Control device . 9. All the connection search table
When the minimum number of cells in the connection becomes 0, the maximum
Number of low-band cells and maximum-band cells to minimum-band cells
9. A means for returning the number of cells obtained by subtracting to the initial value.
Round robin controller.