JP2003134157A - Method and device for controlling multiple buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple buffer controlling method and a multiple buffer controller capable of minimizing frequent packet destruction, congestion control or the like in multiplexing a packet temporarily stored in a memory into a frame. SOLUTION: This multiple buffer controller is provided with a buffer part for making one part obtained by dividing the storage area 2 of the memory 2 into two parts to be a first buffer group 3 to be allocated to respective transmission sources of the packet 15 and making the other divided part to be a second buffer group 4 shared by the transmission sources, an input selecting part 1 for temporarily storing the packet inputted from a plurality of transmission sources in buffers allocated to the respective transmission sources of the first buffer group and selecting a storage destination so as to temporarily store the packet in buffers of the second buffer group in response to a transfer command, and a buffer residual quantity measuring part 7 for monitoring the packet storage quantity of each of the buffers of the first buffer group and giving a transfer command to the input selecting part when the storage quantity exceeds a prescribed threshold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a memory for temporarily storing packets transmitted from a plurality of sources, and controls the input and output of packets to and from the memory when multiplexing the temporarily stored packets into a frame. The present invention relates to a multiple buffer control method and a multiple buffer control device.

[0002]

2. Description of the Related Art A conventional multiplex buffer control device of this type in a packet switching system is disclosed in, for example, Japanese Patent Laid-Open No.
There is one described in Japanese Patent Publication No. 0-168867. Figure 8
FIG. 1 is a block diagram showing a schematic configuration of a multiplex buffer control device described in this publication. In the figure, memory 1
A buffer 12 for a plurality of users n (for example, n = 1, 2, ..., 5) that temporarily stores a packet for each user is configured in one. The memory 11 has a buffer 12 for user n.
Multiplexing unit 1 for multiplexing the packets temporarily stored in each frame into a frame and outputting the multiplexed data to one output line
3 is connected. In the multiplexing unit 13, for example,
A control unit 14 is connected to which a read signal for reading data from the buffer is added according to the priority, a signal for which the output of the multiplexed information is completed is received, and the read signal is added again.

With the above configuration, the packet (also simply referred to as packet) 15 transmitted from each user is temporarily stored in the buffer 12 for the user n, which is fixedly allocated in the memory 11 corresponding to the user, and is controlled. The data is read out according to the output order designated by the section 14, multiplexed by the multiplexing section 13, and then output to one output line.

[0004]

However, in the above-mentioned conventional multiple buffer control device, when the packets 15 input by a plurality of users are multiplexed and output, the buffer 1 for the user n assigned to each user.
Since the packets can be input only for the capacity of 2, the packets are accumulated in the user n buffer 12, and when the buffer 12 is filled with the packets, the input of the packet is prohibited. For this reason, there has been a problem that input packets must be frequently restricted such as congestion control. Further, since the user n buffer 12 is fixedly assigned to each user, even when the buffer used by a certain user is full, the buffers of other users are not being used. However, there is a problem in that the buffer area cannot be used, and the input of the packet of the user who has transmitted the packet 15 having the buffer length or more is prohibited.

The present invention has been made in order to solve these conventional problems. A buffer structure in the memory is provided so that an input packet can be efficiently temporarily stored, and packet discard and congestion control are performed. It is an object of the present invention to provide a multiple buffer control device capable of suppressing such frequent occurrences as much as possible.

[0006]

According to a first aspect of the present invention, there is provided a memory for temporarily storing a plurality of packets, and when the packets temporarily stored in the memory are multiplexed into a frame, a packet is input to the memory. In a multiple buffer control device of a packet switching system for controlling output, a storage area formed in a memory is divided into two, and one of the divided areas is used as a first buffer group to be assigned to each transmission source of a packet. A buffer unit that uses the other as a second buffer group shared by transmission sources, and temporarily stores packets input from a plurality of transmission sources in the buffers assigned to the transmission sources of the first buffer group and transfers the transfer command. An input selection unit for selecting a storage destination so as to temporarily store in a buffer of the second buffer group according to Monitors the packet storage amount, and when the storage amount exceeds a predetermined threshold, at least the output order and the destination for the buffer remaining amount measurement unit that applies a transfer command to the input selection unit and the packet temporarily stored in the buffer unit A control unit for managing and transmitting information regarding the above, and an output port unit for extracting and outputting a packet from the buffer unit according to the information transmitted from the control unit.

With this structure, a buffer structure in the memory is formed so that an input packet can be efficiently temporarily stored, and frequent discarding of packets and congestion control can be suppressed as much as possible.

The invention described in claim 2 is different from the invention described in claim 1 in that it further comprises a user number setting unit for setting the maximum number of users that can be accommodated in the packet switching system.
The control unit divides the storage area of the first buffer group by the number of users set by the user number setting unit, divides the unregistered user buffer unit corresponding to the unregistered user by the number of registered users, and It is added evenly to the user buffer unit corresponding to the user.

With this configuration, the temporary storage area in the memory can be used only by the user who is currently accommodating, so that the capacity of the buffer length allocated to each user becomes large, and the number of packets that can be stored when the number of active users is small. As the number of packets increases, the number of cases where packets are dropped can be reduced.

In addition to the invention described in claim 1, the invention described in claim 3 further comprises a user number setting section for setting the number of users registered in the packet switching system, and the control section is the first. The storage area of the buffer group is divided by the maximum number of users that can be accommodated in the packet switching system, and the unregistered user buffer unit corresponding to the unregistered user is assigned to the shared buffer of the second buffer group.

With this configuration, it is possible to further reduce the situation in which packets are discarded when the number of active users is small.

The invention according to claim 4 is the traffic monitoring for monitoring the traffic of each user buffer formed in the memory for the information on the number of users transmitting packets, in addition to the invention according to claim 1. And a control unit based on the monitoring information of the traffic monitoring unit, when the number of users transmitting packets is large, the storage area of the first buffer group is set relatively to the storage area of the second buffer group. When the number of users sending packets is small,
The storage area of the first buffer group is configured to be relatively small with respect to the storage area of the second buffer group.

With this configuration, a small number of users can use a large-capacity shared buffer group, packet discard can be reduced even when a large number of packets are transmitted, and when the number of packet transmitting users is large. Since the capacity of the buffer unit for each user increases, it is possible to obtain an effect that packets can be evenly accumulated for each user.

In addition to the invention described in claim 4, the invention described in claim 5 further includes a traffic prediction unit for predicting future traffic based on traffic information of each user buffer configured in the memory. The control unit is configured to change the ratio between the first buffer group and the second buffer group according to the predicted traffic.

With this configuration, it is possible to further reduce the situation where packets are discarded, as compared with the fourth embodiment of the present invention.

According to a sixth aspect of the present invention, there is provided a memory for temporarily storing a plurality of packets, and when the packets temporarily stored in the memory are multiplexed into a frame, packet switching for controlling input / output of the packet to / from the memory is performed. In the multiple buffer control method of the system, the storage area of the memory is divided into two, one of the divided areas is used as a first buffer group to be assigned to each transmission source of the packet, and the other divided area is shared by the transmission sources. As a buffer group, packets input from a plurality of transmission sources are temporarily stored in a buffer assigned to each transmission source of the first buffer group, and temporarily stored in a buffer of the second buffer group according to a transfer command. Select a storage destination for, monitor the packet storage amount of each buffer of the first buffer group, and input when the storage amount exceeds a predetermined threshold. A transfer command is added to the selection unit to manage and transmit at least information regarding the output order and the destination for the packet temporarily stored in the buffer unit, and the packet is taken out from the buffer and output according to the transmitted information. .

With this structure, a buffer structure in the memory is formed so that an input packet can be efficiently temporarily stored, and frequent discarding of packets and congestion control can be suppressed as much as possible.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the preferred embodiments shown in the drawings. FIG. 1 is a block diagram showing a first embodiment of a multiplex buffer control device in a packet switching system according to the present invention. In the figure, packets (hereinafter, also simply referred to as packets) 1 respectively input from a plurality of input ports (not shown) 1
5 is input to the memory 2 via the input selection unit 1.
A buffer group for temporarily storing each packet 15 is configured in the memory 2, and the buffer group is individually allocated to the users accommodated in the system, and the user n (n
, 1, 2, ..., N), and a shared buffer group 4 having a storage area equal to that of the user buffer group 3 and shared by each user. Then, the information of the packet 15 accumulated in the buffer group in the memory 2 is managed and the packet 15 to be output is managed.
A control unit 5 for instructing the order of is provided. Further, an output port unit 6 is provided which reads out the packets 15 accumulated in each buffer according to an instruction from the control unit 5, multiplexes them, and outputs the multiplexed data to one output line. Further, the buffer remaining amount measuring unit 7 is provided which measures the packet 15 accumulated in the buffer and adds the storage area switching information for the packet 15 to the input selection unit 1.

The operation of the first embodiment configured as described above will be described below. First, the packet 15 transmitted from the user and accommodated in the system is detected by the input selection unit 1, and when the capacity of the buffer for each user n in the user buffer group 3 is not full, the buffers assigned to each user are Selected and accumulated. At this time, the accumulated amount of each packet in the buffer for the user n (converted into the remaining buffer amount information) is determined by the remaining buffer amount measuring unit 7.
When the packet storage amount exceeds a preset threshold value, the buffer remaining amount measurement unit 7 adds switching information to the input selection unit 1 to be transferred to the shared buffer group 4. The threshold value in this case is set in the buffer remaining amount measuring unit 7. When switching information is added from the buffer remaining amount measuring unit 7 to the input selecting unit 1, the remaining packets 1 exceeding the threshold value
5 is stored in the shared buffer group 4. Therefore, the shared buffer group 4 is an area for accumulating the packets 15 transmitted over the capacity of the buffer of the user buffer group 3 allocated to each user.

Next, the packet 1 accumulated in each buffer
Information such as the destination of 5 and the output order of packets is managed by the control unit 5, and this information is transferred to the output port unit 6 and used for determining the order of output packets and the destination. In this way, the control unit 5 transmits the output order information to the output port unit 6 so as to output the packets 15 in accordance with the designated output order of the packets 15 by looking at the accumulated information of the packets 15. The output port unit 6 takes out the packet 15 from each buffer based on this output order information, multiplexes it, and outputs the multiplexed data to one output line.

In the multi-buffer control device used in the conventional packet switching system, for example, when one or a small number of users transmit more packets 15 than the buffer length assigned to them, the buffer is accumulated. There is a problem that the packet 15 that exceeds the amount is discarded, and as a countermeasure to prevent this, a method of expanding the memory capacity is often used. However, as in the first embodiment described above, when the shared buffer group 4 is provided and there is a free space in the memory, the free space is effectively used to increase the packet capacity without increasing the memory capacity. The effect of reducing the discard of 15 is obtained. In addition, the problem that congestion control or the like of the input packet 15 must be frequently performed is solved.

2 and 3 are block diagrams showing a second embodiment of the multiplex buffer control device according to the present invention in relation to each other. In the figure, the same elements as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, a user number setting unit 8 for setting the number of users to be accommodated in the system and adding the setting information to the control unit 5 is newly provided, and the control unit 5 accordingly stores the buffer configuration information in the memory 2 The difference from the first embodiment shown in FIG.

The operation of the second embodiment configured as described above will be described below, in particular, the part different from the first embodiment in configuration. The user number setting unit 8 is a place for setting the number of users to be accommodated in the system. By setting the number of users here, the number of buffers (= the number of users) and buffers allocated corresponding to the users created in the memory are set. The length (= total capacity / number of users) is determined. By this operation, when the number of users currently registered is less than the maximum number of users accommodated in the system, as shown in FIG. 2, the number of currently registered users is subtracted from the maximum number of users accommodated in the system. There are a large number of unregistered user buffers, that is, free areas. Therefore, in the second embodiment, as shown in FIG. 3, users n (n = 1, 2, ..., Corresponding to M users who have registered the unregistered user buffer, which is an empty area, are registered.
By equally allocating to the M) buffer, users n (n = 1, 2,
, M) buffer capacity is increased.

As a result, the temporary storage area in the memory 2 can be used only by the user who is currently accommodating, as compared with the case where a buffer for the maximum number of users accommodated in the system is provided. Is large, and the number of packets that can be stored is increased when there are few active users (users who are transmitting packets), the effect that the situation in which the packet 15 is discarded can be reduced.

FIG. 4 is a block diagram showing a third embodiment of the multiplex buffer control device according to the present invention. This is the same as the second embodiment shown in FIG. 2 or FIG. 3 in terms of hardware, but the usage of the memory 2 is different.
In the third embodiment, the number of registered users M is set as it is by the number-of-users setting unit 8a, and the buffer length corresponds to the maximum number of users that can be accommodated in the system. The M user buffer group 3 is configured. Then, an unused area of the number of unset users, which is obtained by subtracting the number of users currently set from the maximum number of users accommodated in the system, is added to the shared buffer group 4 and used.

With this configuration, the memory 2
It is said that the packet 15 is discarded because the amount of packets that can be accumulated increases when the number of active users is small because the free area in the area can be reduced and the buffer length of the shared buffer group 4 is increased. The effect of reducing the situation is obtained.

5 and 6 are block diagrams showing a fourth embodiment of the multiplex buffer controller according to the present invention.
In the figure, the same elements as those of FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. This is different from the configuration of FIG. 4 in that a traffic monitoring unit 9 for monitoring the amount of packets 15 transmitted from each user is added to the buffer remaining amount measuring unit 7 constituting the fourth embodiment. There is.

The present embodiment configured as described above is
In particular, a part having a configuration different from that of FIG. 4 will be described. The traffic monitoring unit 9 assigns a user buffer group 3 to each user for all buffer areas of the memory 2,
It has a function of changing the ratio with the shared buffer group 4 shared by each user by increasing or decreasing the number of users by monitoring traffic.

That is, the traffic monitoring unit 9 monitors the traffic of all the buffers within a preset fixed time, counts the number of users transmitting the packet 15, and stores it. When the number of active users is small after a lapse of a certain time, the traffic monitoring unit 9 assigns a user buffer group 3 to each user as shown in FIG.
, And the ratio of the shared buffer group 4 is increased. On the contrary, when the number of active users is large, as shown in FIG. 6, the ratio of the user buffer group 3 allocated to each user is increased and the ratio of the shared buffer group 4 is decreased.

As described above, the criterion for changing the ratio between the user buffer group 3 and the shared buffer group 4 in the memory 2 is greater than the preset value set in the traffic monitoring unit 9 or this set value. When it is lower than the other set value that is lower than the above, it is changed at regular intervals.

In this way, according to the fourth embodiment, when the number of packet transmission users is small, the capacity of the shared buffer group 4 increases, so that a small number of users can share the large capacity of the shared buffer group 4. Can be used, and the effect that the packet discard can be reduced even if a large number of packets 15 are transmitted is obtained. Further, when the number of packet transmission users is large, the capacity of the buffer unit for each user increases, so that the effect that the packets 15 can be evenly stored for each user is obtained.

FIG. 7 is a block diagram showing a fifth embodiment of the multiplex buffer control device according to the present invention. In the figure, the same elements as those of the fourth embodiment shown in FIG. 5 or 6 are designated by the same reference numerals, and the description thereof will be omitted. The fourth point is that the traffic monitoring unit 9 constituting the fourth embodiment is provided with a traffic prediction unit 10 that predicts an approximate number of active users and adds the prediction information to the control unit 5.
The configuration is different from that of the embodiment.

The present embodiment configured as described above is
In particular, a part different in configuration from the fourth embodiment will be described. The traffic estimation unit 10 accumulates data on the number of active users monitored by the traffic monitoring unit 9 for a certain period of time, predicts an approximate number of active users in the future from the data, and controls information for changing the buffer ratio of the memory in advance. Give to part 5. With such a configuration, it is possible to provide a buffer configuration that is effective for packet storage at that moment, so that it is possible to further reduce the situation in which packets are discarded, as compared with the fourth embodiment. The effect is obtained.

[0034]

As is apparent from the above description, according to the present invention, the buffer structure in the memory is performed so that the input packet can be efficiently temporarily stored, and the packet discarding and the congestion control can be performed. It is possible to provide a multiple buffer control device capable of suppressing frequent operations as much as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a multiplex buffer control device according to the present invention.

FIG. 2 is a block diagram showing a related technique of a second embodiment of a multiplex buffer control device according to the present invention.

FIG. 3 is a block diagram showing a second embodiment of a multiplex buffer control device according to the present invention.

FIG. 4 is a block diagram showing a third embodiment of a multiplex buffer control device according to the present invention.

FIG. 5 is a block diagram showing a fourth embodiment of a multiplex buffer control device according to the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of a multiplex buffer control device according to the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of a multiplex buffer control device according to the present invention.

FIG. 8 is a block diagram showing a schematic configuration of a conventional multiple buffer control device in a packet switching system.

[Explanation of symbols]

1 Input selection section 2 memory 3 user buffer group (first buffer group) 4 Shared buffer group (second buffer group) 5 control unit 6 output ports 7 Buffer remaining amount measurement unit 8, 8a User number setting section 9 Traffic monitoring unit 10 Traffic forecasting section 15 packets

Claims (6)

[Claims] 1. A multiplex buffer control of a packet switching system, comprising: a memory for temporarily storing a plurality of packets, and controlling the input and output of the packets to and from the memory when multiplexing the packets temporarily stored in the memory into a frame. In the device, a second buffer which is configured in the memory and whose storage area is divided into two, one of which is divided into a first buffer group which is assigned to each source of the packet, and the other of which is divided is shared by the source And a buffer unit that is a buffer group of the first buffer group, and temporarily stores packets input from a plurality of sources in the buffers assigned to the respective sources of the first buffer group, and according to a transfer command, the second buffer group. An input selection unit that selects a storage destination so that the buffer is temporarily stored in the buffer, and packet storage of each buffer of the first buffer group. And a buffer remaining amount measuring unit that applies a transfer command to the input selection unit when the accumulated amount exceeds a predetermined threshold, and at least the output order and the destination for the packets temporarily stored in the buffer unit. A multiplex buffer control device comprising: a control unit that manages and transmits information regarding the information, and an output port unit that extracts and outputs a packet from the buffer unit according to the information transmitted from the control unit. 2. A packet number switching system comprising a user number setting unit for setting a maximum number of users that can be accommodated in the packet switching system, wherein the control unit stores the first buffer group according to the user number set by the user number setting unit. The area is divided, the unregistered user buffer section corresponding to the unregistered user is divided by the number of registered users, and the user buffer sections corresponding to the registered users are evenly allocated.
The multiple buffer control device described in 1. 3. A user number setting unit for setting the number of users registered in the packet switching system, wherein the control unit has the maximum number of users that can accommodate the storage area of the first buffer group in the packet switching system. 2. The multiplex buffer control device according to claim 1, wherein the multiplex buffer is divided by 1 and an unregistered user buffer unit corresponding to an unregistered user is assigned to a shared buffer of the second buffer group. 4. A traffic monitoring unit for monitoring the traffic of each user buffer formed in the memory for information on the number of users transmitting packets, wherein the control unit transmits packets based on the monitoring information of the traffic monitoring unit. When the number of users who are transmitting is large, the storage area of the first buffer group is increased relatively to the storage area of the second buffer group, and when the number of users transmitting packets is small, the first buffer group is 2. The multiple buffer control device according to claim 1, wherein the storage area of the group is relatively small with respect to the storage area of the second buffer group. 5. A traffic predicting unit that predicts future traffic based on traffic information of each user buffer configured in the memory, and the control unit includes the first buffer group according to the predicted traffic. 5. The multiplex buffer control device according to claim 4, wherein the ratio of the second buffer group to the second buffer group is changed. 6. A multiplex buffer control of a packet switching system, comprising: a memory for temporarily storing a plurality of packets, and controlling the input and output of the packets to and from the memory when the packets temporarily stored in the memory are multiplexed into a frame. In the method, the storage area of the memory is divided into two, one of the divided portions is a first buffer group assigned to each transmission source of the packet, and the other divided portion is a second buffer group shared by the transmission sources, Stored so that packets input from a plurality of transmission sources are temporarily stored in the buffers assigned to the transmission sources of the first buffer group, and temporarily stored in the buffers of the second buffer group according to a transfer command. Select the destination, monitor the packet storage amount of each buffer of the first buffer group, when the storage amount exceeds a predetermined threshold, A transfer command is added to the input selection unit, with respect to a packet temporarily stored in the buffer unit, information about at least an output order and a destination is managed and transmitted, and a packet is extracted from the buffer according to the transmitted information. A multiple buffer control method characterized by outputting.