JP2000299686A - Scheduling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform scheduling in economical configuration concerning a scheduling device having packet queues to which respectively different use bands are allocated. SOLUTION: A packet input part 13 stores an inputted packet in one of plural packet queues 14 corresponding to the use band of that packet. At every unit time such as packet transmission interval, a scheduling managing part 15 applies the right of transmission to one of packet queues 14 having scheduled transmission time after current time and changes the scheduled transmission time of this packet queue, to which the transmission right is applied, corresponding to the use band. Besides, at every unit time as mentioned above, the scheduling managing part 15 selects one of packet queues, which has the transmission right of packets and stores the packets, as a transmission object packet queue. In a packet output part 16, the packet is read out of the packet queue 14 selected by the scheduling managing part 15 and outputted to a packet output line 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ATM (Asynchronous
The present invention relates to a scheduling device that temporarily stores packets and controls reading of the stored packets in a node device using a packet communication technology such as Transfer Mode.

[0002]

2. Description of the Related Art As a conventional apparatus of this type, for example, an apparatus described in Japanese Patent Application Laid-Open No. 6-276209 is known. FIG. 31 is a block diagram of this conventional device. A plurality of packet queues 100 provided for each VP (Virtual Path), a packet input line 101, a packet input unit 102, a packet output unit 103, an output timing It comprises a determination unit 104, a clock unit 105, a read control memory 106, and a packet output line 107.

The VP of a packet input from the packet input line 101 is identified in a packet input unit 102 and written into a corresponding packet queue among a plurality of packet queues 100. At the same time as writing this packet, the output timing determination unit 104
5, the next available output time of the packet queue 100 in which the packet was written this time is obtained based on the current bandwidth indicated by the current time and the bandwidth used according to the VP. The VP of the performed packet is written in the read control memory 106.

The read control memory 106 is supplied with the current time output from the clock unit 105 as a read address, and reads the VP stored in accordance with the read address. The packet output unit 103 reads a packet from the packet queue 100 corresponding to the VP supplied from the read control memory 106 and outputs the packet to the packet output line 107.

[0005]

The above-mentioned conventional scheduling device obtains the output possible time every time a packet is input, and a large number of packets are input during a packet transmission interval (unit time). In such a case, it is necessary to obtain the output possible time for each packet. Therefore, there is a problem that the output timing discrimination unit must be configured using an expensive device capable of high-speed processing.

Further, in the conventional scheduling device,
When the available output time is obtained, the used bandwidth is referred to. However, information on the used bandwidth is generally stored in an external storage device because the amount of information increases. Therefore, in the conventional scheduling device that obtains the output available time every time a packet is input, the output available time can be obtained even when a large number of packets are input during a unit time. There is also a problem that an expensive external storage device having a high access speed is required.

Further, in the conventional scheduling device,
Since the configuration for performing fair scheduling according to the attribute of the packet queue is not clearly shown, there is a problem that it is difficult to perform fair scheduling.

An object of the present invention is to provide a scheduling apparatus that can perform fair scheduling with an economical configuration.

[0009]

According to the present invention, in order to achieve the above object, a plurality of packet storage means each assigned a different use band, and a plurality of input packets are stored in accordance with the use band. A packet input means for inputting to one of the packet storage means; and a transmission right by giving a packet transmission right to one of the packet storage means whose current time has passed the scheduled transmission time for each unit time. Is updated in accordance with the bandwidth used by the packet storage means, and one of the packet storage means having the packet transmission right and storing the packet is sent to the transmission destination. A scheduling management means to be selected as the packet storage means; and a packet reading and outputting packet from the packet storage means selected by the scheduling management means. The essential feature in that an Tsu preparative output means.

In this configuration, for each unit time such as a packet transmission interval, the scheduling management means gives a packet transmission right to one of the packet storage means whose current time has passed the scheduled transmission time. At the same time, the scheduled transmission time of the packet storage means to which the transmission right has been given is updated according to the band used by the packet storage means. Therefore, even when a large number of packets are input during a unit time, the scheduled output time of at most one packet storage means can be obtained. It becomes possible to do. Even when the bandwidth used by the packet storage means is stored in the external storage device, it is sufficient to access the external storage device at most once during a unit time, so that it is slower and cheaper than the conventional technology. External storage devices can be used.

The scheduling management means includes, for example, a time management section for managing the current time, a bandwidth management section for managing the bandwidth used by each of the packet storage means, and a storage for managing the packet storage status of each of the packet storage means. A management unit, a transmission right management unit that manages the number of transmission rights held by each of the packet storage units, and a current time managed by the time management unit passing the scheduled transmission time for each unit time. The transmission right is given to one of the packet storage means, and the scheduled transmission time of the packet storage means to which the transmission right is given is changed according to the band used by the packet storage means managed by the band management unit. The bandwidth control unit and, for each unit time, indicate that the information managed by the transmission right management unit has the transmission right and that the information managed by the accumulation management unit is a packet. Composed of a queue selector for selecting one of the packet storage means indicates that it is the product as delivered target packet accumulating means.

The band control unit includes a register unit that manages a scheduled packet transmission time and a comparison unit that raises a request signal when the current time has passed the scheduled transmission time as a result of comparing the current time with the scheduled transmission time. Is provided for each packet storage unit, a band scheduler unit that selects only one request signal from the request signals sent from the comparison unit and notifies the transmission right management unit, and a packet storage unit that has selected the request signal. For this purpose, a scheduled time calculation unit for recalculating and updating the next scheduled packet transmission time is provided.

As a result, the number of packet accumulating units to which a transmission right is given within a unit time is at most one, and a plurality of packet accumulating units do not update the scheduled transmission time at the same time, and use band information is held. The number of accesses to the external storage device per unit time is at most one, and it is possible to configure the scheduling device even with the external storage device having a low access speed.

When selecting only one of the request signals sent from the comparing section corresponding to the packet storage means, the bandwidth scheduler section outputs the request signal corresponding to the packet storage means belonging to the same traffic class. After selecting only one by rotation priority control from among them, select only one by rotation priority control or absolute priority control or a combination of these from the request signal selected for each traffic class, or support packet storage means Then, when only one of the request signals sent from the comparison unit is selected, the packet storage unit having the packet stored is preferentially selected, so that the fairness according to the attribute of the packet storage unit is selected. Scheduling can be performed.

Further, in the present invention, the queue selecting unit refers to the transmission right holding status of each packet storage unit managed by the transmission right management unit and the accumulation status of each packet storage unit managed by the storage management unit, and performs transmission. A transmission request unit for raising a request signal when there is a packet to be transmitted and there is a packet to be transmitted, for each packet storage unit, and selecting only one request signal from the request signals transmitted from the transmission request unit. A queue scheduler for notifying the packet output unit and the transmission right management unit of the packet, but when selecting only one of the request signals from the transmission request unit corresponding to the packet storage unit, the same traffic After selecting only one of the request signals corresponding to the packet storage means belonging to the class by the rotation priority control,
A request signal selected by a rotation priority control or an absolute priority control or a combination thereof from among the request signals selected in each traffic class, or a request signal selected at a predetermined selection timing and each selection timing At a specific timing, a request signal corresponding to a packet storage unit belonging to a specific destination is selected at a specific timing according to a correspondence relationship with a destination to which the packet belongs, and rotation priority control is performed from among request signals corresponding to packet storage units belonging to the same destination. Alternatively, by configuring such that only one is selected by absolute priority control or a combination thereof, it is possible to perform fair scheduling according to the attribute of the packet storage means. Also, when only one of the request signals sent from the transmission request unit is selected in correspondence with the packet storage means, the packet storage means having the higher priority is preferentially selected, and thus the same as the above is performed. Is obtained.

Further, in the present invention, the transmission right management unit manages, for each packet storage unit, how many packets are currently transmitted, and selects a queue at the same packet transmission timing. After the number of transmittable packets corresponding to the packet storage unit notified from the unit is reduced, the number of transmittable packets corresponding to the packet storage unit notified from the bandwidth control unit is increased, so that no packets are stored. It is possible to keep the transmission right acquired at times. Further, by setting an upper limit on the number of transmittable packets managed by the transmission right management unit for each packet storage unit, when packets arrive intensively at the packet storage unit that has not stored packets for a long period of time, other packets can be stored. The influence on the storage means can be minimized. Also, at the same packet transmission timing, even if the packet control means specified by the bandwidth control unit and the queue selection unit are the same and the transmission right has reached the maximum value, the reduction processing is executed first, so that a new The operation of the band control unit and the operation of the queue selection unit can be executed completely in parallel and independently as long as the acquired transmission right is not lost and the update timing of the transmission right is kept. Even if the unit time is shortened due to an increase in the line speed, it is not necessary to execute both operations serially, so that it is possible to complete the operation within the unit time.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. As shown in FIG. 1, the scheduling device 11 of the present embodiment stores a plurality of packet queues 14 each serving as a packet storage unit and a packet input via the packet input line 12 in the plurality of packet queues 14. Packet input unit 13 stored in an appropriate packet queue 14
A scheduling management unit 15 for selecting a packet queue 14 to output a packet from among the plurality of packet queues 14, and reading out a packet from the packet queue 14 selected by the scheduling management unit 15 at the time of packet transmission and sending the packet to a packet output line 17. It has a packet output unit 16 for outputting and an external storage device 18. here,
The packet queue 14 can be provided in various units, such as for each virtual connection, for each traffic class (which may be simply called a class), for each destination, or a combination of two or more of them. It is assumed that a packet queue 14 is provided for each combination of destinations (# 1 to #N) and destinations (# 1 to #N).

FIG. 2 is a block diagram showing a configuration example of the scheduling management unit 15. As shown in the figure, the scheduling management unit 15 includes a time management unit 25 that manages the current time, and a bandwidth that manages the used bandwidth allocated to each packet queue 14 using a table on the external storage device 18. A management unit 24, a transmission right management unit 22 that manages the number of transmission rights of packets held by each packet queue 14, a storage management unit 26 that manages a packet storage status in each packet queue 14, 14
And a bandwidth control unit 21 that manages to give a transmission right at a time interval corresponding to the used band allocated to the packet queue 14 irrespective of whether the packet is stored in the packet queue 14 or not. And a queue selecting unit 23 for selecting a packet queue from which the packet is read out of the packet queue 14.

FIG. 3 shows that the bandwidth management unit 24
FIG. 4 is a diagram showing a configuration example of a table on an external storage device used to manage the bandwidths used for each of the four. In the present embodiment, the used bandwidth BW and the corresponding transmission time interval I
Both NTs are stored for each packet queue. of course,
You can save only one of them. Band used B
When only W is stored, the transmission time interval INT may be calculated according to an appropriate formula when the transmission time interval INT is required.
The converse is also true. Also, a priority PR set for each packet queue is set.

FIG. 4 shows an example of the configuration of a table provided in the storage management unit 26 for storing the packet storage status of each packet queue 14. In the present embodiment, the number of stored packets QL is stored for each packet queue. This table can be provided on the external storage device 18.

FIG. 5 shows an example of the configuration of a table provided in the transmission right management unit 22 for storing the number of transmission rights for each packet queue 14. In this embodiment, the number of packets PN (transmission right) permitted to be transmitted is stored for each packet queue. This table can be provided on the external storage device 18.

FIG. 6 is a flowchart showing a processing example of the transmission right management unit 22. As shown in the figure, the transmission right management unit 22 determines if the packet queue 14 is designated by the queue selection unit 23 at the packet transmission timing.
The number of transmission rights of the specified packet queue 14 stored in the table shown in FIG. 5 is reduced by 1 (steps S101 and S102). Further, the transmission right management unit 22
Increases the number of transmission rights of the specified packet queue 14 stored in the table shown in FIG. 5 by 1 if the packet queue 14 is specified by the band control unit 21 (steps S103 and S105). ). However, if the number of transmission rights has already reached the maximum value at the stage before the increase, the number of transmission rights is not increased (step S104).

FIG. 7 is a block diagram showing a configuration example of the band control unit 21. As shown in FIG.
A register unit 31 provided for each packet queue 14 and holding a scheduled packet transmission time of the corresponding packet queue 14, and each register unit 31 provided for each register unit 31 corresponding to the current time indicated by the time management unit 25. The comparing unit 32 compares the scheduled packet transmission time held in the register unit 31 and raises a request signal when the current time has passed the scheduled packet transmission time.
2, a bandwidth scheduler unit 33 that selects only one request signal from the request signals listed above and notifies the transmission right management unit 22 of the request signal, and a next packet for the packet queue 14 whose request signal is selected by the bandwidth scheduler unit 33. A scheduled time calculating unit 34 for recalculating the scheduled sending time and setting the calculation result in the register unit 31 corresponding to the packet queue 14. Note that the initial value set in each register unit 31 is such that if the time management unit 25 indicates “0” as the current time at the start of operation,
The time corresponds to the value of the transmission time interval of the corresponding packet queue 14 itself. The comparing unit 32 has, for example, a configuration shown in FIG.

FIG. 9 is a flowchart showing a processing example of the band control unit 21. At the packet transmission timing, each comparing unit 32 stores the current time in the register unit 3 corresponding to the current time.
If the scheduled packet transmission time held in No. 1 has passed, a request signal is output (step S201). 1
When the request signals are output from the number of comparison units 32 or more, the band scheduler unit 33 selects only one of the request signals, and transmits the packet queue identifier corresponding to the selected request signal to the transmission right management unit 22 and the scheduled time. The calculation unit 34 is notified (steps S202 and S203). The scheduled time calculation unit 34, based on the used band of the packet queue indicated by the notified packet queue identifier among the used bands of each packet queue 14 stored in the band management unit 24, Is calculated again, and the calculation result is stored in the corresponding register unit 31 (step S204).

FIG. 10 is a block diagram showing an example of the configuration of the band scheduler 33 in the band controller 21. The bandwidth scheduler unit 33 manages a traffic class, a destination, and a virtual connection to which each packet queue 14 belongs, and selects one of the request signals from the comparison unit 32 provided corresponding to each packet queue 14. When selecting only one, first, from the request signals of the packet queues 14 belonging to the same traffic class, only one is selected by the rotation priority selector unit 41 for each traffic class. In the case of this embodiment, the packet queue 14
Belongs to the traffic class #
1, # 2 and # 3, there are three rotation priority selectors 41. The rotation priority selector unit 41 is a functional block that selects a request signal according to a rotation priority control policy. The rotation priority control is to check whether the request signals are output in a predetermined order, This is a priority control method in which one of the request signals searched earliest is selected. In the next selection operation, the search is started from the request signal located next to the request signal selected last time. In the present embodiment, the rotation priority selector unit 41 is prepared to select only one of the request signals of the packet queue 14 belonging to the same traffic class, but a selector unit based on the other control policy is applied. That is within the scope of the present invention. After selecting the request signal, the rotation priority selector 41 for each class outputs the selected request signal to the inter-class rotation priority selector 42. The inter-class rotation priority selector unit 42 selects only one of the request signals selected by the rotation priority selector unit 41 for each class by the rotation priority control. In this embodiment, the rotation priority selector unit 42 is prepared to select only one of the request signals selected by the rotation priority selector unit 41 for each class. However, selector units based on other control policies are provided. The application is within the scope of the present invention. For example, an absolute priority control policy that preferentially selects a request signal of a class having a high priority according to a predetermined priority or a selector unit that operates based on a combination of a rotation priority control policy and an absolute priority control policy is considered. Can be

FIG. 11 is a block diagram showing a configuration example of the queue selection unit 23. As shown in the figure, the queue selecting unit 23 compares the transmission right holding state for each packet queue managed by the transmission right management unit 22 and the packet accumulation state for each packet queue managed by the accumulation management unit 26. A transmission request unit 51 provided for each packet queue 14 for raising a request signal when it is determined that the corresponding packet queue 14 has a transmission right and stores packets to be transmitted, One of the request signals from the plurality of transmission request units 51 is selected, and an identifier of the packet queue corresponding to the request signal is notified to the transmission right management unit 22, the packet output unit 16, and the accumulation management unit 26. And a queue scheduler 52. FIG.
Next, an example of the configuration of the transmission request unit 51 will be described.

FIG. 13 is a flowchart showing a processing example of the queue selecting section 23. At the packet transmission timing, each transmission request unit 51 sets the corresponding packet queue 1
If the packet No. 4 stores the packet and has the transmission right, it outputs a request signal (step S301). When a request signal is output from one or more transmission request units 51,
The queue scheduler 52 selects one request signal, and notifies the transmission right management unit 22, the packet output unit 16, and the accumulation management unit 26 of the packet queue identifier corresponding to the selected request signal (steps S302, S3).
03).

FIG. 14 is a block diagram showing a configuration example of the queue scheduler 52 in the queue selector 23. The queue scheduler unit 52 manages each packet queue 14 for each traffic class, destination, and virtual connection, and selects one of the request signals from the transmission request unit 51 provided corresponding to each packet queue 14. When selecting only one, first, the rotation priority selector 61 selects only one of the request signals corresponding to the packet queues 14 belonging to the same class. In the present embodiment, the rotation priority selector unit 61 is prepared to select only one of the request signals corresponding to the packet queues 14 belonging to the same traffic class. The application is within the scope of the present invention. After selecting the request signal, the rotation priority selector unit 61 for each class outputs the selected request signal to the inter-class rotation priority selector unit 62. The inter-class rotation priority selector 62 selects only one of the request signals selected by the rotation priority selector 61 for each class by rotation priority control, and outputs an identifier of a packet queue corresponding to the selected request signal. I do. In the present embodiment, the rotation priority selector unit 62 is prepared to select only one of the request signals selected by the rotation priority selector unit 61 for each class. However, selector units based on other control policies are provided. The application is within the scope of the present invention. For example, an absolute priority control policy that preferentially selects a request signal of a class having a high priority according to a predetermined priority or a selector unit that operates based on a combination of a rotation priority control policy and an absolute priority control policy is considered. Can be

Next, the operation of this embodiment will be described. When a packet is input via the packet input line 12, the packet input unit 13 in the scheduling device 11 outputs one of the packet queues 14 among the plurality of packet queues 14 based on the header information and the attribute information of the virtual connection to which the packet belongs. In addition to storing the packet, the identifier of the packet queue 14 storing the packet is notified to the scheduling management unit 15. In general, there are a plurality of packet input lines 12.

When notified of the packet queue identifier from the packet input unit 13, the accumulation management unit 26 in the scheduling management unit 15 corresponds to the packet queue identifier in the table shown in FIG. 4 provided therein. The accumulated number is incremented by one.

The scheduling management unit 15 also performs the processing shown in the flowchart of FIG. 9 regardless of the notification of the packet queue identifier from the packet input unit 13. Hereinafter, this processing will be described with an example.

FIG. 15 is a state diagram for explaining the processing shown in the flowchart of FIG. Each comparing unit 32 refers to the current time CT managed by the time management unit 25 and outputs a request signal when the current time CT has passed the scheduled transmission time ST of the corresponding packet queue 14 (FIG. 9, FIG. Step S20
1). The scheduled transmission time ST is stored in the register unit 31. As the management of the current time CT, it is typical to use a counter that counts up every time the unit time T elapses.

In the example of FIG. 15, since the current time CT = 130 has passed the scheduled transmission time ST, (class #
1, destination # 2), (class # 1, destination # 3), (class # 2, destination # 1), (class # 2, destination # 3), (class # 3, destination # 1). A request signal is output from the comparison unit 32 corresponding to the packet queue.
As the state of the band scheduler unit 33, the inter-class rotation priority selector unit 42 selects the class # 3 last time, and the rotation priority selector units 41 of the classes # 1 to # 3 respectively select the destination # 2, the destination # 3, and the destination. # 3 is selected.
Here, the inter-class rotation priority selector unit 42 determines that the class #
Suppose that request signals are searched in the order of 1 → # 2 → # 3 → # 1 → ‥‥. In addition, the rotation priority selector unit 41 for each class outputs the destination # 1 → # 2 → # 3 → ‥‥ → # N → # 1 → ‥
Suppose that the request signal is searched in the order of ‥.

The rotation priority selectors 41 of class # 1, class # 2, and class # 3 search from the next to the request signal selected last time according to the determined order, and search for destination # 3, destination # 1, and destination # 1, respectively. A request signal corresponding to the packet queue of # 1 is selected. Next, the inter-class rotation priority selector unit 42 selects the class # 1 by searching from the next to the request signal selected last time according to the determined order (FIG. 9, step S20).
2). As a result, the band control unit 21 (class # 1,
Since the packet queue 14 corresponding to the destination # 3 is selected, the corresponding packet queue identifier is output to the transmission right management unit 22 and the scheduled time calculation unit 34 (Step S).
203). FIG. 16 shows the state of the band control unit 21 at this time.

When notified of the identifier of the packet queue of (class # 1, destination # 3), the scheduled time calculation unit 34 performs an operation shown in the following equation (1) to obtain (class # 1, destination # 3).
The next scheduled transmission time n of the packet queue 14 of the destination # 3)
ew Recalculate ST. new ST = old ST + INT (1)

Here, old ST is the previous scheduled transmission time, new ST is the next scheduled transmission time, and INT is the transmission interval. The transmission interval INT is obtained by referring to information stored in a table on the external storage device 18 managed by the band management unit 24. In this example, since the old ST of the packet queue 14 corresponding to (class # 1, destination # 3) is "119" and the INT is "25", "144" is set as the new ST (class # 1, destination # 3). Register part 3 of packet queue 14 corresponding to # 3)
It is set to 1 (step S204). In addition, as a state after the completion of the selection operation, the inter-class rotation priority selector unit 42 changes the previously selected class to “class # 1”, and the rotation priority selector unit 41 of class # 1 changes the previously selected destination to the “destination”. # 3 ". FIG. 17 shows the state of the band control unit 21 at this time.

On the other hand, the transmission right management unit 22
When the packet queue identifier is notified from 1, the number of transmittable packets registered corresponding to the packet queue identifier among the number of transmittable packets (transmission right) held in the table shown in FIG. The number is incremented by one (FIG. 6, step S105).

As described above, the band control unit 21 according to the present embodiment
In the prior art, it is necessary to calculate the scheduled transmission time for one packet queue at each packet transmission timing. In comparison, it is possible to configure using inexpensive parts having a slow processing speed. Also, since the external storage device 18 is accessed only once each time a packet is transmitted, a low-speed and inexpensive external storage device is used as compared with a conventional external storage device accessed each time a packet arrives. It becomes possible to do.

FIG. 18 is a state diagram for explaining the operation of the queue selection unit 23. The transmission request unit 51 refers to the table managed by the transmission right management unit 22 and the accumulation management unit 26, and transmits a request signal when both the transmission right and the accumulation packet remain in the corresponding packet queue. .

In the example of FIG. 18, (class # 1, destination #
2) In the packet queue 14 having the attributes of (class # 1, destination # 3), (class # 2, destination # 1), (class # 2, destination # 3), (class # 3, destination # 1). A request signal is output from the corresponding transmission request unit 51. As the state of the queue scheduler 52, the inter-class rotation priority selector 62 selects the class # 1 last time, and the rotation priority selectors 61 of the classes # 1, # 2, and # 3.
, Destination # 1, destination # 2, and destination # 2 are selected, respectively. Here, it is assumed that the inter-class rotation priority selector unit 62 searches for a request signal in the order of class # 1 → # 2 → # 3 → # 1 → ‥‥. In addition, the rotation priority selector unit 61 for each class determines the destination # 1 → # 2 → # 3 → ‥‥ → # N → #
Suppose that request signals are searched in the order of 1 → ‥‥.

The rotation priority selectors 61 of the classes # 1, # 2, and # 3 search from the next to the request signal selected last time in accordance with the determined order, and
A request signal corresponding to the packet queues 14 of the destination # 3 and the destination # 1 is selected. Next, the inter-class rotation priority selector 62 selects the class # 2 by searching from the next to the request signal selected last time according to the determined order. As a result, the queue selecting unit 23 determines that the packet queue 1 corresponding to (class # 2, destination # 3)
4 is selected, and the corresponding packet queue identifier is output to the transmission right management unit 22, the packet output unit 16, and the accumulation management unit 26 (FIG. 19). As a state after the completion of the selection operation, the inter-class rotation priority selector 62 changes the class selected twice to class # 2, and the rotation priority selector 61 of class # 2 changes the previously selected destination to destination # 3 ( (FIG. 20).

The packet output unit 16 extracts a packet from the packet queue 14 having the designated packet queue identifier and outputs the packet to the packet output line 17. The transmission right management unit 22 reduces the number of transmittable packets held by the packet queue 14 of the designated packet queue identifier by one. The accumulation management unit 26 reduces the number of accumulated packets in the packet queue 14 of the designated packet queue identifier by one.

As described above, the queue scheduler 52
Is the same class when the packet queue 14 is managed for each class, destination, or virtual connection, and only one of the request signals output from the transmission request unit 51 corresponding to the packet queue 14 is selected. After selecting only one of the request signals corresponding to the packet queues 14 belonging to the class by the rotation priority control, and selecting only one of the request signals selected in each class by the rotation priority control. In addition, it is possible to perform fair scheduling for a plurality of packet queues 14 according to attributes.

FIG. 21 is a state diagram for explaining the operation of the transmission right management unit 22. In the example of FIG. 21, the packet queue 14 corresponding to (class # 1, destination # 3) is specified from the bandwidth control unit 21, and the packet queue corresponding to (class # 2, destination # 1) is specified from the queue selection unit 23. Queue 1
4 is specified. At this time, the transmission right management unit 22
As shown in FIG. 22, the number of packets that can be transmitted from the packet queue 14 corresponding to (class # 2, destination # 1) is "1".
After changing the number to “11”, which is a reduced number (FIG. 6, step S
102), as shown in FIG. 23, (class # 1, destination #
The number of packets that can be transmitted from the packet queue 14 corresponding to 3) is changed to “4” which is increased by “1” (FIG. 6, step S105). As described above, the transmission right management unit 22 manages, for each packet queue, how many packets are currently held to transmit, and the queue selection unit 2
3, the number of transmittable packets corresponding to the packet queue 14 notified from the bandwidth control unit 21 is reduced, and then the number of transmittable packets corresponding to the packet queue 14 notified from the bandwidth control unit 21 is increased. It is possible to retain the transmission right acquired when there is no transmission right.

Further, as shown in step S104 of FIG. 6, the transmission right management unit 22 sets an upper limit on the accumulation of the number of transmittable packets managed for each packet queue.
It is possible to minimize the influence on the other packet queues 14 when the packets intensively arrive at the packet queue 14 in which no packet has been stored for a long period of time. Also, at the same packet transmission timing, the packet queue 1
4, the number of packets that can be transmitted is reduced first, and the packet queue 14 specified by the bandwidth control unit 21 and the queue selection unit 23 is the same, and the acquisition transmission right has reached the maximum value. Even in this case, there is no problem if the operation of the band control unit 21 and the operation of the queue selection unit 23 can be executed completely in parallel and independently as long as the transmission right acquired is not lost and the update timing of the transmission right is kept. Both operations can be completed within the unit time T even if the unit time is shortened due to an increase in speed.

FIG. 24 is a block diagram showing another example of the configuration of the queue scheduler 52 in the queue selector 23. The queue scheduler unit 52 shown in FIG. 6 gives priority to the packet queue 14 given a high priority when selecting only one of the request signals from the transmission request unit 51 corresponding to each packet queue 14. The high priority determination unit 63, the low priority determination unit 64, and the absolute priority selector unit 65 are used in order to prevent the packet queue 14 for which the transmission stop is instructed from the output destination of the packet or the like. Prepare. FIG. 25 and FIG. 26 are diagrams illustrating configuration examples of the high priority determination unit 63 and the low priority determination unit 64, respectively.

The high-priority judging section 63 sets each packet queue 1
4 are provided. Then, each high priority determination unit 63
Transmits the request signal when the priority of the request signal output from the corresponding transmission request unit 51 is set to “high” and the corresponding packet queue 14 is not instructed to stop transmission. The priority of each packet queue 14 is managed by the bandwidth management unit 24. Similarly, the low priority determination unit 64 is provided for each packet queue 14. Then, each low priority determination unit 64 determines that the priority of the request signal output from the corresponding transmission request unit 51 is “low”.
And the request signal is passed when the corresponding packet queue is not instructed to stop transmission.
Accordingly, the rotation priority selector 61 connected to the high priority determination unit 63 processes only the request signal of the packet queue 14 whose priority is set to “high”, and the rotation priority selector 61 connected to the low priority determination unit 64. The priority selector 61 processes only the request signal of the packet queue 14 whose priority is set to “low”.

The absolute priority selector section 65 selects the request signal passed through the high priority determination section 63 with absolute priority. With such a configuration, the processing according to the dynamically changing state of the packet queue 14 is performed by the queue scheduler unit 5.
2, it is possible to simplify the configuration of the band control unit 21 and to provide a plurality of packet queues 14 with services according to priority.

FIG. 27 is a block diagram showing another example of the configuration of the queue scheduler 52.
A high-priority determination unit 63 provided for each transmission request unit 51;
Corresponding to the low-priority determining unit 64, the high-priority determining unit 63 having the same destination, or the rotation-priority controlling unit 66 provided corresponding to the low-priority determining unit 64. One selector unit 67a provided and one selector unit 67 provided corresponding to the low priority determination unit 64.
b, a destination designation section 68, and an absolute priority selector section 69.

For example, at the first, second,..., Nth, (N + 1) th,.
At a specific timing, a specific destination is specified, for example, 2,..., #N, # 1,. The rotation priority selector unit 66 performs rotation priority control on one request signal from request signals added from the transmission request unit 51 corresponding to the packet queue 14 having the same destination via the high priority determination unit 63 or the low priority determination unit 64. And output. In other words, the rotation priority selector unit 66 searches for request signals of a plurality of classes having the same destination in a predetermined order from the class next to the previously selected class, and finds one request signal found first. Output a signal.

The selector section 67a is added from the transmission request section 51 corresponding to each packet queue 14 via the high priority determination section 63 and is output from the request signal output via the rotation priority selector section 66. And outputs a request signal belonging to the destination specified by the request.
Further, the selector 67 b is added from the transmission requesting unit 51 corresponding to each packet queue 14 via the low priority determining unit 64 and is output from the request signal output via the rotation priority selector 66 to the destination specifying unit. A request signal belonging to the destination designated by 68 is selected and output. The absolute priority selector 69 selects the request signal from the selector 67a when it is output,
When the request signal is not output from the selector 67a, the request signal output from the selector 67b is selected.

FIG. 28 is a block diagram showing another example of the configuration of the band scheduler 33 in the band controller 21. The bandwidth scheduler 33 shown in FIG.
In order to preferentially select the packet queue 14 in which packets are stored when only one of the request signals sent from the comparison unit 32 is selected in correspondence with No. 4 A storage non-determination section 44 and an absolute priority selector section 45 are provided. FIGS. 29 and 30 are block diagrams showing configuration examples of the accumulation determination section 43 and the accumulation non-determination section 44, respectively.

The storage presence judging section 43 checks each packet queue 1
4 are provided. Then, each of the storage presence determination units 43
When a packet is stored in the corresponding packet queue 14, the request signal output from the corresponding comparing unit 32 is passed. Similarly, the accumulation non-determination unit 44
It is provided for each packet queue 14. When no packet is stored in the corresponding packet queue 14, each storage non-determination unit 44 passes the request signal output from the corresponding comparison unit 32. Accordingly, the rotation priority selector unit 41 connected to the storage presence determination unit 43
Processes only the request signal of the packet queue 14 with packet accumulation, and the rotation priority selector 41 connected to the accumulation non-determination unit 44 processes only the request signal of the packet queue 14 without packet accumulation. become.

The absolute priority selector 45 selects the request signal that has passed through the accumulation determining section 43 with absolute priority. With such a configuration, it is possible to prevent the packet queue 14 having no packet storage from being given the transmission right first, thereby preventing the delay time of the actually stored packet from deteriorating.

The present invention provides an ATM for replacing fixed length ATM cells.
The present invention can be applied not only to a cell switch but also to a packet switch for exchanging packets of variable length, and similar improvement effects can be expected.

[0057]

As described above, according to the scheduling apparatus of the present invention, at every unit time such as a packet transmission interval, a packet is stored in one of the packet storage means whose current time has passed the scheduled transmission time. And the right to send
Since the scheduled transmission time of the packet storage means to which the transmission right is given is updated according to the bandwidth used by the packet storage means, even if a plurality of packets are input during a unit time, at most one packet storage means can be used. May be calculated. Therefore, as compared with the conventional technology in which the scheduled transmission time has to be obtained every time a packet is input, the scheduling device can be configured using a low-speed and inexpensive processing device or an external storage device. There is an effect that can be realized at low cost.

Furthermore, fair scheduling according to attributes can be performed on a plurality of packet queues according to queue selection rules such as rotation priority control and absolute priority control provided by the bandwidth scheduler and the queue scheduler.

The transmission right management unit reduces the number of transmittable packets (the number of transmission rights) corresponding to the packet queue notified from the queue selection unit at the same packet transmission timing, and then transmits the packet notified from the band control unit. By increasing the number of transmittable packets corresponding to the queue, the transmission right can be updated without losing the transmission right even when the packet queue specified by the bandwidth control unit and the queue selection unit is the same at the same packet transmission timing. As long as the timing is maintained, the operation of the bandwidth control unit and the operation of the queue selection unit can be executed completely in parallel and independently, and even if the line speed is increased and the unit time is shortened, both operations can be performed in the unit time. It is possible to complete within.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a scheduling management unit 15;

FIG. 3 is a diagram illustrating a configuration example of a table managed by a band management unit 24.

FIG. 4 is a diagram showing a configuration example of a table managed by a storage management unit 26;

FIG. 5 is a diagram illustrating a configuration example of a table managed by a transmission right management unit 22;

FIG. 6 is a flowchart illustrating a processing example of a transmission right management unit 22;

FIG. 7 is a block diagram illustrating a configuration example of a band control unit 21;

8 is a block diagram illustrating a configuration example of a comparison unit 32. FIG.

FIG. 9 is a flowchart illustrating a processing example of a band control unit 21;

FIG. 10 is a block diagram illustrating a configuration example of a band scheduler unit 33.

11 is a block diagram illustrating a configuration example of a queue selection unit 23. FIG.

FIG. 12 is a block diagram showing a configuration example of a transmission request unit 51.

FIG. 13 is a flowchart illustrating a processing example of a queue selection unit 23;

14 is a block diagram illustrating a configuration example of a queue scheduler unit 52. FIG.

FIG. 15 is a state diagram showing an operation process of the band control unit 21;

FIG. 16 is a state diagram showing an operation process of the band control unit 21;

FIG. 17 is a state diagram showing an operation process of the band control unit 21;

FIG. 18 is a state diagram showing an operation process of the queue selection unit 23.

FIG. 19 is a state diagram showing an operation process of the queue selection unit 23.

FIG. 20 is a state diagram showing an operation process of the queue selection unit 23;

FIG. 21 is a state diagram showing an operation process of the transmission right management unit 22;

FIG. 22 is a state diagram showing an operation process of the transmission right management unit 22;

FIG. 23 is a state diagram showing an operation process of the transmission right management unit 22;

24 is a block diagram illustrating another configuration example of the queue scheduler unit 52. FIG.

FIG. 25 is a block diagram illustrating a configuration example of a high-priority determination unit 63.

FIG. 26 is a block diagram illustrating a configuration example of a low priority determination unit 64.

FIG. 27 is a block diagram illustrating another configuration example of the queue scheduler unit 52.

FIG. 28 is a block diagram illustrating another configuration example of the band scheduler unit 33.

FIG. 29 is a block diagram illustrating a configuration example of a storage presence determination unit 43;

30 is a block diagram illustrating a configuration example of a non-accumulation determining unit 44. FIG.

FIG. 31 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Scheduling device 12 ... Packet input line 13 ... Packet input unit 14 ... Packet queue 15 ... Scheduling management unit 16 ... Packet output unit 17 ... Packet output line 18 ... External storage device 21 ... Band control unit 22 ... Sending right management unit 23 Queue selection unit 24 Band management unit 25 Time management unit 26 Storage management unit 31 Register unit 32 Comparison unit 33 Band scheduler unit 34 Scheduled time calculation unit 41 Rotation priority selector unit 42 Inter-class rotation priority Selector unit 43: Accumulation determination unit 44: Accumulation non-judgment unit 45: Absolute priority selector unit 51: Transmission request unit 52: Queue scheduler unit 61: Rotation priority selector unit 62: Inter-class rotation priority selector unit 63: High priority determination unit 64 low priority determination unit 65 absolute priority selector unit 66a, 66b selector 67a, 67b ... rotation priority selector section 68 ... destination designation section 69 ... absolute priority selector section 100 ... packet queue 101 ... packet input line 102 ... packet input section 103 ... packet output section 104 ... output timing determination section 105 ... clock section 106 ... Read control memory 107: Packet output line

Continued on the front page (72) Inventor Hiroyuki Iwamoto 5-7-1 Shiba, Minato-ku, Tokyo F-term within NEC Corporation 5K030 GA01 GA04 HA10 HB14 HB29 KA21 KX12 KX18 MB15 9A001 BB03 BB04 CC03 DD10 JJ12 KK56

Claims (13)

[Claims] 1. A plurality of packet storage means each assigned a different use bandwidth, and a packet input means for inputting an input packet to one of the plurality of packet storage means according to the use bandwidth. And granting a packet transmission right to one of the packet storage units whose current time has passed the scheduled transmission time for each unit time, and storing the scheduled transmission time of the packet storage unit to which the transmission right has been assigned to the packet storage unit. Scheduling management means for updating according to the bandwidth used by the means, selecting one of the packet storage means having a packet transmission right and storing the packets as a transmission target packet storage means, Packet output means for reading and outputting a packet from the packet storage means selected by the means. Turing device. 2. The scheduling management unit includes: a time management unit that manages a current time; a band management unit that manages a band used by each of the packet storage units; and a packet storage status of each of the packet storage units. A storage management unit, a transmission right management unit that manages the number of transmission rights held by each of the packet storage units, and a current time managed by the time management unit that exceeds the scheduled transmission time for each unit time. The right to send is given to one of the packet storage means that has been given the right to send, and the scheduled sending time of the packet storage means to which the right to send is given is changed according to the band used by the packet storage means managed by the band management unit. A bandwidth control unit that performs, for each unit time, indicating that the information managed by the transmission right management unit has the transmission right, and that the information managed by the accumulation management unit 2. The scheduling device according to claim 1, further comprising: a queue selection unit that selects one of the packet storage units indicating that the packet is stored as a transmission target packet storage unit. 3. The packet selection unit according to claim 1, wherein the queue selection unit excludes the packet storage unit that has received the transmission stop instruction when there is a packet storage unit that has received the transmission stop instruction from the packet output destination. 3. The scheduling device according to claim 2, wherein the scheduling device has a configuration for selecting the following. 4. The bandwidth control unit is provided for each of the packet storage units, and a register unit for setting a scheduled transmission time of the corresponding packet storage unit is provided. A comparison unit that compares a scheduled transmission time set in the unit with a current time managed by the time management unit, and outputs a request signal when the current time is past the scheduled transmission time; A band scheduler unit for selecting one of the request signals output from the unit; and a scheduled transmission time set in a register unit corresponding to the request signal selected by the band scheduler unit. 4. The schedule according to claim 2, further comprising: a scheduled time calculating unit that changes the signal according to a band used by the packet storage unit corresponding to the signal. Packaging equipment. 5. The bandwidth scheduler section comprises: one of request signals output from each of the comparing sections;
When selecting one request signal, for each request signal output from the comparison unit belonging to the same traffic class, select only one request signal from the request signals, and then select from the request signals selected for each traffic class. 5. The scheduling apparatus according to claim 4, wherein said scheduling apparatus has a configuration for selecting only one request signal. 6. The bandwidth scheduler section comprises: one of the request signals output from each of the comparing sections;
6. The scheduling according to claim 4, wherein when selecting one of the request signals, the request signal output from the comparison unit corresponding to the packet storage unit in which the packet is stored is preferentially selected. apparatus. 7. The queue selection unit is provided for each of the packet storage units. The transmission right management unit and the storage management unit determine that the corresponding packet storage unit has a transmission right and stores packets. When the information managed by the transmission request unit indicates, the transmission request unit that outputs the request signal, and one of the request signals output from each transmission request unit
7. The scheduling apparatus according to claim 2, further comprising: a queue scheduler unit for selecting and outputting one of them. 8. The queue scheduler unit, when selecting one of the request signals output from each of the transmission request units, one of the request signals of the transmission request units belonging to the same traffic class. 8. The scheduling apparatus according to claim 7, wherein after selecting only the request signals, only one request signal is selected from the request signals selected in each traffic class. 9. The queue scheduler section, when selecting one of the request signals output from each of the transmission request sections, a request signal selected at a predetermined selection timing and at each selection timing. A request signal belonging to a destination to be selected at the present selection timing is selected from the request signals output from the transmission request units based on the correspondence relationship with the destination to which the selected The scheduling device according to claim 7, wherein the scheduling device has a configuration for selecting one request signal from request signals belonging to a destination. 10. The configuration in which the queue scheduler unit selects, when selecting one of the request signals output from each of the transmission request units, a packet storage unit to which a high priority is given. 10. The scheduling device according to claim 7, wherein the scheduling device comprises: 11. The queue scheduler unit, when selecting one of the request signals output from the transmission request units, does not select a packet storage unit instructed to stop transmission. 11. The scheduling device according to claim 7, 8, 9 or 10. 12. The transmission right management unit, after decrementing the number of transmission rights of the packet storage means selected by the queue selection unit at a packet transmission timing, the packet to which the transmission right is given by the band control unit. 6. A configuration for managing the number of transmission rights of each of said packet storage means by increasing the number of transmission rights of said storage means.
The scheduling device according to 6, 7, 8, 9, 10, or 11. 13. The transmission right management unit, when the number of transmission rights to the packet storage unit to which the transmission right is given by the band control unit has reached a predetermined maximum value, the packet storage unit. 13. The scheduling apparatus according to claim 12, wherein the scheduling apparatus has a configuration that does not increase the number of transmission rights.