JP2001016206A - Frequency band common share controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a defect that transmission of an idle cell to a channel takes place in spite of the presence of a cell to be sent to a group with lower priority by executing frequency band common share control similarly to the case of selection control of connection even for group selection control. SOLUTION: Second frequency band common share control is applied to cells resident in a 2nd queue buffer provided corresponding to each group so as to utilize up to a maximum frequency band of an output channel similarly to the case with frequency band common share control conducted corresponding to connection even in the case that the connection is grouped. That is, this controller is provided with 2nd queue buffers QBA-QBC that are provided for each group and temporarily store cells to be sent, and also with 2nd frequency band common share control means CONT(G) and MUX(G) that decide read sequence of cells according to the frequency and assignment set in advance to each group on the basis of the information of the cells resident in the 2nd queue buffers QBA-QBC.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an ATM (Asynchrono).
us Transmission Mode, asynchronous transmission mode) Used for communication. The present invention provides a minimum bandwidth (MCR, Minimum Cell Rate) and a maximum bandwidth (PC
R, Peak Cell Rate), which relates to an improvement in band sharing control for selecting a transmission cell so as to share a band of a transmission path. In particular, two-stage selection control is performed such that a group is formed for a plurality of connections from which cells from the user arrive, and a transmission cell is allocated to one VP (Virtual Path, virtual high-speed multiplex transmission line) for the plurality of connections. Regarding the improvement when doing.

2. Description of the Related Art FIG. 8 is a block diagram of a conventional band sharing control device. Cells from each user are managed on a connection (line) basis, and connections C1 to C in FIG.
Arriving at 12. Connection information and the like are recorded in the header of this cell. Each connection C1
C12 has a queue buffer QB1 for temporarily staying.
QB12 are provided, and the arriving cell is accumulated in this queue buffer and waits for transmission to the line. The connections C1 to C12 are classified into groups Gr1 to Gr3 according to a preset priority. Each group is provided with a band sharing control circuit CONT. According to the control, cells staying in each queue buffer are read out to the multiplexers MUX provided for each group, and transmitted from the multiplexer MUX to the line VP by the selector SEL. The band sharing control circuit CONT monitors the cells staying in the queue buffer provided corresponding to the connection in the group, refers to the band sharing control table T, and adjusts the connection band up to the maximum band set in the group. It is controlled to share.

Here, in the conventional apparatus shown in FIG. 8, the selector SEL for selecting each group is controlled by the schedule counter SC. That is, the read band of the group is configured to be periodically allocated according to the priority set for the group. For example, if the selection timing of the groups A, B, and C is simply 6: 3: 1, the schedule counter SC selects the group A six times out of ten times, selects the group B three times, It is set to select group C at least once. This configuration is fixed and cannot cope with the situation of cells staying in each group. In this situation, there are no cells staying in the group B by chance, and there are a large number of cells staying in the group C and waiting for transmission. In the group C, the staying cells are discarded due to time over. Also group B
When the selection is set to, an empty cell is transmitted. This does not violate the contract with the user,
This means that the transmittable band is not being used effectively. The present invention has been made in such a background, and even when connections are grouped according to priority or maximum available bandwidth, when there are cells waiting to be transmitted to another group. It is another object of the present invention to provide a control device capable of performing effective bandwidth sharing control without useless time slots. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM communication system that reduces the number of cells discarded by band sharing control. An object of the present invention is to improve the utilization rate of an ATM communication network.

According to the present invention, even when connections are grouped, a second queue buffer is provided corresponding to the group, and cells staying in the second queue buffer are connected. Similar to the bandwidth sharing control, the second bandwidth sharing control is performed so as to use up to the maximum bandwidth of the output line. That is, the present invention provides a connection (C1 to C12) from which a cell from a user arrives, a first queue buffer (QB1 to QB12) provided for each connection and temporarily storing a cell to be transmitted, A group is formed for each of a plurality of queue buffers, and reading is performed in accordance with a preset band allocation based on a contract (including MCR and CPR) set for each user for cells staying in the queue buffer within the group. First band sharing control means (CONT (C), MUX
(C)) and a group selecting means for allocating cells selected by the first band sharing control means to a line (VP) for each of the plurality of groups and transmitting the cells. The selection means includes a second queue buffer (QBA to QBC) provided for each group for temporarily storing cells to be transmitted, and information of cells staying in the second queue buffer, which is set in advance for each group. Second band sharing control means (CONT for determining the reading order according to band allocation)
(G) and MUX (G)).
Reference numerals in parentheses are reference numerals of the embodiment drawings which are displayed so that the configuration is easy to understand. The second band sharing control means (CONT (G), MUX (G)) includes a control table (T) in which the read logic of cells staying in the second queue buffer is recorded for each group, Means for executing read control according to the control table. Then, when there is a cell staying in the second queue buffer after the read control is executed, reading of the cell staying in the second queue buffer is performed until the maximum bandwidth of the line is used. It is. According to the present invention, there is provided a monitoring circuit for monitoring the staying state of the second queue buffers (QBA to QBC) and instructing the first band sharing control means to stop reading when the staying cells may overflow. SV). The output circuit of the group selecting means may be provided with a shaper (SH) for suppressing the fluctuation generated under the control of the second band sharing control means. The second queue buffer may be set inside the first queue buffer without providing the second queue buffer as hardware separate from the first queue buffer. With this configuration, the entire hardware can be designed small. With this configuration,
Since band sharing control can be performed across groups, if there is no cell to be selectively transmitted in one group even though another group has cells to be selectively transmitted, the transmission timing of that group Transmission of an empty cell is avoided, and the transmission band can be effectively used up to CPR according to the contract. According to the present invention, cells to be discarded can be reduced, and the utilization efficiency of the ATM communication network can be improved.

(First Embodiment) FIG. 1 is a block diagram of a first embodiment of the present invention. Cells from each user are managed on a connection (line) basis and arrive at connections C1 to C12. Connection information and the like are recorded in the header of this cell. Each of the connections C1 to C12 is provided with a queue buffer QB1 to QB12 for temporarily staying, and the arriving cell is accumulated in the queue buffer and waits for transmission to the line. The connections C1 to C12 are classified into groups Gr1 to Gr3 according to a preset maximum use bandwidth. In this example, the maximum bandwidth used is 30 for group A.
Mbps, group B 70 Mbps, group C 5
0Mbps, total bandwidth of three groups is 150M
bps. A first band sharing control circuit CONT (C) is provided in each group, and the cells staying in each queue buffer are read out to the multiplexer MUX provided for each group according to the control. Band sharing control circuit CON
T (C) monitors cells staying in a queue buffer provided for a connection in the group, and controls to share the connection bandwidth up to the maximum bandwidth set for the group. Here, as a feature of the present invention,
Second queue buffers QBA to QBC are provided for each group and temporarily store cells to be transmitted. A read order is determined based on information of cells staying in the second queue buffer in accordance with a band allocation preset for each group. And second band sharing control means (CONT (G) and MUX (G)) for determining The output section of the second band sharing control means is provided with a shaper for suppressing the fluctuation caused by the second band sharing control means to prevent the band capacity from being exceeded. FIG. 2 shows the second band sharing control means CO.
FIG. 3 is a more detailed block diagram of NT (G) and MUX (G). The second band sharing control means includes a control table T in which read logic of cells staying in the second queue buffer is recorded for each group, and means for executing read control according to the control table. If there are still cells staying in the second queue buffer after the read control is executed, the reading of the cells staying in the second queue buffer is performed until the maximum bandwidth of the line is used. Be composed. FIG.
Is basically the same as the first bandwidth sharing control means provided for each group for a plurality of connections. That is, the same configuration is obtained by replacing the queue buffers QBA to QBC with the connection-compatible queue buffers (QBn). Therefore, the second bandwidth sharing control means can be realized by changing the control specifications using the same hardware and software as the conventionally used first bandwidth sharing control means. . That is, in the control table T of FIG. 2, the table shown in FIG. 3 is installed for the queue buffer corresponding to the connection, and the table shown in FIG. 4 is installed for the queue buffer corresponding to the group. In the device shown in FIG.
If there is a cell in any of the queue buffers, OR
The queue stay flag becomes "1" by logic, and it can be recognized that cells are staying in lower priority cells. At this time, it is necessary to read out empty information (a state in which reading is not executed). It can be controlled to eliminate it. FIG. 3A is an example of a control table showing read logic for four connections of group A, FIG. 3B is three connections of group B, and FIG. The minimum guaranteed bandwidth is set for each connection in accordance with the contract (or report), and the priority is set based on the read management table. Each "1" in the table reads out,
“0” indicates that reading is not performed. This configuration is the same as the conventional device. FIG. 4 is an embodiment of a control table showing read logic for three groups. As described above, for each of the three groups, the maximum bandwidth used is 30 Mbps for group A and 70 Mbps for group B.
Mbps, group C is 50 Mbps, and the total bandwidth of the three groups is 150 Mbps. This shares one line (VP). In FIG. 4, the conditions of the read timing are set according to the ratio of the maximum band for each group. In this readout table, "1" means that reading is possible, and at the position of "0" means that there is no reading right for the group. The table has seven slots,
The initial value starts from slot 1. In slot 1, all of groups A, B, and C have access rights. At this time, the three groups are prioritized, and the priority of the group A is the highest and the priority of the group C is the lowest, such as A>B> C. In slot 1, groups A,
Reading is performed in the order of B and C, and the processing of slot 1 is completed by reading all of them. In this way, the sequence proceeds as in slots 2, 3, 4,. FIG. 5 shows a control flowchart of the main part of this control. In the initial state, a read request is waited for with reference to the head column position of the group read table. A read request is issued at the read timing position, and it is determined whether or not there is read data in the group to be read. In this judgment, the cell staying state of each queue buffer is checked immediately before the read timing, and the next group to be read next is determined with reference to the read table. When a plurality of pieces of information to be read exist in the same column, the state is managed using a flag indicating the existence. In this case, the reading is executed by the logical product of the valid flag and the reading table.
Once reading is performed, the flag is set to "0" and removed from the reading target. When there is no group whose flag is "0", all groups are to be read. When there are a plurality of reading targets, the reading groups are determined in accordance with the order set in advance by the specification of the managing side. As a result, reading of the determined group is executed,
At this time, a read flag from the queue buffer is set, and
Prepare to give access rights to other groups competing for reading in the same column of the reading table. In this way, this process is repeated until there are no more read candidates at the search position of the group to be read in the control table (the column of the control table), and when all the reading is completed in that column, the search in the next column is stopped. Be started. In this manner, reading of the empty information which is not read out by referring to all the columns of the control table may be executed (the left end in FIG. 5) only when there is no cell to be read out in all the groups. . As described above, according to the control of the present invention, the reading of the empty information is not executed even if there is a cell to be read in another group. FIG.
Is an operation time chart of the apparatus of this embodiment. The display of [the present invention] in FIG. 6 is the operation of the apparatus of the present invention, and the operation of the conventional apparatus described in FIG. 8 is shown in the display of [conventional example] for comparison. The input information is shown in the uppermost row IN. The status of the queue buffer in each group and the value of the control table are shown. The values in this control table correspond to FIG. Then, the value of each time slot of this control table is displayed in the assignment column. In this example, it is displayed that it takes one time slot to execute the reading process of the queue buffer. The output OUT in each case is shown at the bottom of the embodiment of the present invention and the bottom of the conventional example in FIG. As can be seen from FIG. 6, in the conventional device, since the selector SEL executes a fixed cyclic selection according to the schedule counter SC, the output OUT outputs "X".
In such a case, cells staying in the queue buffer of the low-priority group are read out, and the bandwidth sharing control is performed up to the maximum available bandwidth. Can be understood. (Second Embodiment) FIG. 7 is a block diagram of an apparatus according to a second embodiment of the present invention. This is a configuration diagram in the case where the second queue buffer for the group is not provided separately as hardware but the second queue buffer is substantially set inside the first queue buffer for the connection. In the description of the first embodiment, it has been described that the information is temporarily stored in the group queue buffer. However, the group queue sharing control is performed in the first queue buffer existing for each group using the connection queue buffer. By changing the state of use of the memory address by applying the signal of (1), the second queue buffer can be substantially set. With such a configuration, the read control based on the second band sharing control can be similarly executed. In the configuration of the second embodiment, equivalent control is executed by using only two levels of control signals without using a two-stage queue buffer as hardware. In this configuration, the connection bandwidth sharing control of each group is controlled by an assignment signal for each group from the group bandwidth sharing control such that the connection bandwidth sharing control of each group becomes effective when the group is assigned to execute reading. In the group bandwidth sharing control, the presence or absence of cell stay in each group is monitored,
The same control can be performed so as to give a read right to a group having a stay. Further, as in the first embodiment, the output section of the second band sharing control means includes a shaper for suppressing fluctuation caused by the second band sharing control means to prevent the band capacity from being exceeded. . FIG. 9 shows the operation of the shaper. The shaper constantly monitors the cell interval and controls the cell interval so that it does not fall below a defined minimum cell interval. If the input is shorter than the minimum cell interval, an output delay is added.
In the example of FIG. 9, since the cell interval between the cells is equal to or less than the minimum cell interval, the output of the cell is delayed to the minimum cell interval to prevent the band from being exceeded. Further, since the interval between the cells is longer than the minimum cell interval, the cells are output without delay. Similarly, since the distance between the cells is smaller than the minimum cell interval, the cells are delayed so as to secure the minimum cell interval. As described above, the shaper operates so as to constantly monitor the interval between cells and prevent an excess of the bandwidth capacity. According to the configuration of the second embodiment, since the movement of the cell by the second band control means is eliminated, the area where the same information is temporarily recorded is temporarily eliminated, and two types of queue buffers are provided. There is no need to set a margin for each. Therefore, there is an effect that the use efficiency of the queue buffer is increased and the scale of the hardware can be substantially reduced.

As described above, by executing the same band sharing control as that of the connection selection control in the group selection control, the maximum bandwidth of the line can be used. It is possible to eliminate the irrationality of transmitting an empty cell without being given a transmission right while cells to be transmitted are staying. The present invention can be implemented by providing a circuit similar to the band sharing control for a connection that has been well known in the related art. According to the present invention, the utilization efficiency of the ATM communication network can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a second band sharing control unit of the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a control table of the apparatus according to the embodiment of the present invention (first band sharing control means);

FIG. 4 is a configuration diagram of a control table of the apparatus according to the embodiment of the present invention (second band sharing control means);

FIG. 5 is a control flowchart of a main part of the apparatus according to the embodiment of the present invention.

FIG. 6 is an operation time chart of the apparatus according to the embodiment of the present invention and the conventional apparatus.

FIG. 7 is a block diagram of a device according to a second embodiment of the present invention.

FIG. 8 is a block diagram of a conventional example.

FIG. 9 is a diagram of a shaper operation.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Manabu Yoshino 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Norihito Ienaga 3-192-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation F-term (reference) 5K030 GA03 HA10 KA03 KA04 LC02 LC09 LC11 MA13 MB15

Claims (4)

[Claims] 1. A first queue buffer provided for each connection from which a cell from a user arrives and temporarily storing cells to be transmitted, and a group is formed for each of a plurality of the first queue buffers. A first band sharing control unit that determines a reading order according to a preset band allocation for cells staying in the queue buffer, and a plurality of the groups selected by the first band sharing control unit. And a group selecting means for allocating the cells to the line and transmitting the cells, wherein the group selecting means comprises a second queue buffer provided for each group and temporarily storing cells to be transmitted, and According to the information on the cells staying in the second queue buffer, the bandwidth was set in advance for each group. Second band sharing control means for determining a reading order so as to use up to the maximum bandwidth of the line, wherein the second band sharing control means A band sharing control device comprising: a control table in which the read logic is recorded correspondingly; and means for executing read control in accordance with the control table. 2. A monitoring circuit for monitoring a stagnant state of said second queue buffer and instructing said first band sharing control means to stop reading when said stagnant cells may overflow. Item 2. The bandwidth sharing control device according to Item 1. 3. The bandwidth sharing control device according to claim 1, wherein an output circuit of said group selection means includes a shaper for suppressing a fluctuation generated under the control of said second bandwidth sharing control means. 4. A control signal for directly determining a reading order under the control of said second bandwidth sharing control means without providing said second queue buffer as hardware separate from said first queue buffer. 2. The bandwidth sharing control device according to claim 1, wherein the bandwidth sharing control device is realized by integrating the second queue buffer and the first queue buffer by being used for read control of a first bandwidth sharing control unit.