JP2001274795A - Cell-shaping unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cell-shaping unit, adopting the generic cell rate algorithm(GCRA) system that solves a clamping problem and suppresses inversion of cell transmission sequence. SOLUTION: The cell-shaping unit is provided with queues that are provided to each connection and store cells in the order of arrival from the head of a queue and with an input means that stores the arrived cells to the queue, corresponding to the connection to which the cells belong. A scheduling means is provided with a means that calculates a cell transmission possible time and decides it, when the cell stored in the queue reached the head of the queue and with a means that updates a parameter, corresponding to the connection to which the cell belongs, when a cell transmission means transmits the cell to a line. The cell transmission means detects a cell, whose transmission possible time decided by the scheduling means is earlier than the present time, extracts the cell whose transmission possible time is the earliest time, from the head of the queue and transmits the cell to the line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell shaping apparatus for fixed-length packets (cells) such as ATM cells, and more particularly to a GCRA (Generic Cell R).
This technique is effective when applied to a cell shaping device realized by the ATE (Algorithm) method.

[0002]

2. Description of the Related Art A cell shaping device is a device for giving a delay time to a cell as needed so as to conform to a traffic characteristic value determined for each connection.

Conventionally, there are two types of shapers that are different in principle from each other. One is the token method,
The other is the GCRA method.

FIG. 1 shows an example of a cell shaping apparatus (hereinafter, referred to as a shaper) 100 using a conventional token system.
It is shown in FIG. Conventional shaper 100 using token method
Are input means 101 and queue 10 as shown in FIG.
2, 103; transmission timing generating means 104, 105;
It comprises arbitration means 106.

In the example shown in FIG. 14, the operation of the shaper 100 according to the conventional token system will be described.
The cells arriving at the shaper are input to the queues 102, 1 corresponding to the connection to which the cell belongs by the input means 101.
03 or the like. Here, the connection means a virtual path or channel identified by part or all of the VPI and VCI fields included in the cell header.

[0006] The queues 102 and 103 store cells in the order of arrival from the head, and exist for connection.

Transmission timing generating means 104, 105
Generates a timing signal indicating that the head cell of each of the queues 102 and 103 can be transmitted, and exists for each queue corresponding to the connection. Further, the transmission timing generating means 104 and 105 can be realized by a method of generating a timing signal by dividing the frequency of a clock signal according to the traffic characteristic value for each connection. This is disclosed in the specifications of Japanese Patent Application Nos. 10-18457 and 10-281500.

[0008] The arbitration means 106 takes out the cell from the head of the queue in which the timing signal indicating that the cell can be transmitted is generated, and transmits the cell to the line. At this time, if there are a plurality of queues from which cells can be transmitted, the arbitration means 106 sets a fixed priority set in advance between the queues,
A queue for taking out cells is selected based on arbitration rules such as round robin, random, or a combination thereof.

Next, FIG. 15 shows an example of realizing the shaper 200 according to the conventional GCRA method.

A conventional shaper 200 using the GCRA method.
As shown in FIG. 15, a storage unit 201 for storing traffic characteristic values and parameter values, a clock unit 202, a scheduling unit 203, and a cell transmission unit 204.

In the embodiment shown in FIG. 15, a cell shaping device (shaper) based on the conventional GCRA system is used.
The operation of 200 will be described.

The storage means 201 is a means for storing traffic characteristic values and parameter values for each connection, and is constituted by an array addressed by the value of the connection identifier. Here, the connection means a virtual path or channel identified by part or all of the VPI and VCI fields included in the cell header.

As shown in FIG. 15, when a cell arrives at a shaper, these values corresponding to the arriving cell connection are stored in a storage means 201 for storing traffic characteristic values and parameter values for each connection. 203 is input.

The scheduling means 203 receives the input traffic characteristic value, parameter value,
Based on the current time counted by 2, the transmittable time of the arriving cell is determined and output to the cell transmitting means 204.

At the same time, the scheduling means 203
Storage means 20 for determining the updated value of the parameter value and storing the traffic characteristic value and parameter value for each connection
1 to update the stored parameter values.

[0016] When a cell arrives at the shaper, the cell transmitting means 204 identifies the cell which has arrived and the scheduling means 2.
The transmission possible time of the cell determined in step 03 is stored as a pair.

The cell transmitting means 204 detects a cell whose transmittable time is before the current time from the stored cells based on the current time counted by the clock means 202, and transmits the cell to the line. I do.

Next, an operation example of the scheduling means 203 of the shaper 200 according to the conventional GCRA method will be described. FIG. 16 is a flowchart showing an operation example of the scheduling means 203 shown in FIG. Regarding the operation of the scheduling means 203, for example,
Kan Toyoshima, "CDV Reduction Shaping Algorithmin
ATM Networks, "IEICE Trans. Commun., Vol. E79-B,
No. 4, Apr. 1996.

In the flow chart shown in FIG. 16, a cell interval value and a permissible cell delay time fluctuation are used as traffic characteristic values, the current time when calculating a cell transmittable time is ta, and the cell belongs. The cell interval value of the traffic characteristic value corresponding to the connection is T, the allowable cell delay time fluctuation value is τ, the parameter value corresponding to the connection to which the cell belongs is TET, and the transmittable time of the cell is ts. .

The shaper scheduling means 203 according to the conventional GCRA system firstly determines that a cell is
When the cell arrives at 0, it receives input of a cell interval value T, a permissible cell delay time fluctuation τ, and a parameter value TET, which are traffic characteristic values corresponding to the connection to which this cell belongs.

The scheduling means 203 performs the processing shown in the flowchart of FIG. 16 on the basis of the input cell interval value T, the allowable cell delay time fluctuation τ, the parameter value TET, and the current time ta counted by the clock means 202. Start the operation shown in.

When the relation of ta ≦ TET is satisfied, the transmission possible time ts of the cell is defined as TET, and the parameter value T
Update ET to TET + T (Steps 301 and 30)
3, 306).

If the relationship of ta> TET is established, the transmission possible time ts of the cell is set to ta (step 301,
302). In this case, if the relationship of ta ≦ TET + τ is satisfied, the parameter value TET is changed to TET + T
(Steps 304 and 306).

If the relationship of ta> TET + τ holds, the parameter value TET is updated to ta−τ + T (steps 304, 305, 306).

The transmittable time t of the cell determined in this way
s is output to the cell transmission means 204. Further, the updated parameter value TET is output to the storage unit 201 that stores the traffic characteristic value and the parameter for each connection, and the stored parameter value is updated.

Next, an example of the operation of the cell transmission means 204 of the shaper according to the conventional GCRA method will be described. FIG.
FIG. 16 is a diagram showing an example of implementation of the cell transmission means 204 in FIG. 15, and is generally called a ring buffer system. About this, for example, Pierre Boyer, Fabrice Guille
min, Michel Servel, Jean-Pierre Coudreuse, "Speceing
Cells Protects and Enhances Utilization of ATM Ne
twork Links "IEEE Network, Vol. 6, No. 5, Sep. 1992.

In FIG. 17, reference numeral 401 denotes a pointer indicating a buffer corresponding to the current time, and reference numerals 402, 403, and 404 denote buffers 1, 2, and N for storing cells.

The operation of the cell transmission means 204 of the shaper 200 according to the conventional GCRA method will be described with reference to FIG.

In the ring buffer system, the time required for transferring one cell on a line (about 2.7 μsec for an STM-1 / STS-3c line) is defined as one time slot, and as shown in FIG. This is a method in which buffers for storing cells corresponding to the current time are arranged in a ring, and cells in a time slot corresponding to the current time are sequentially transmitted.

Specifically, in FIG. 17, the buffer indicated by the pointer 401 indicating the buffer corresponding to the current time stores a cell corresponding to the time slot at the current time. Here, the time normalized by the time required for one time slot, that is, (time / time required for one time slot) is called a normalized time, and the normalized current time in FIG. Assuming that the number is N, the buffer on the right side of this buffer stores cells whose transmission possible time is the normalized time t + 1, and the buffer on the left side is the normalized time t + N-1.

The pointer 401 indicating the buffer corresponding to the current time is updated based on the time counted by the clock means 202.

When a cell arrives at the shaper, the ring buffer stores the arriving cell in a buffer of a time slot corresponding to the transmittable time of the cell determined by the scheduling means 203, so that the arriving cell and the transmittable time are stored. Are stored in pairs. However, if another cell is already stored in the buffer of the time slot corresponding to the transmittable time, an empty buffer is searched in time order, and the cell is stored in the nearest empty buffer. The ring buffer transmits a cell of the buffer indicated by the pointer 401 indicating the buffer corresponding to the current time to the line, thereby selecting a cell whose transmittable time is earlier than the current time from the cells stored in the ring buffer. Detect and send to line.

A second operation example of the cell transmission means 204 of the shaper according to the conventional GCRA system will be described. FIG.
FIG. 8 is a diagram showing an implementation example of the cell transmission means 204 shown in FIG. 15, which is generally called a calendar system. For example, see EugenWallmeier, Tom Worster,
The spacing Policser, An Algorithm for Efficient P
eak Bit Rate Control in ATM Networks, "ISS 1992, Oc
t.1992.

Reference numeral 501 shown in FIG. 18 is a pointer indicating a list corresponding to the current time, and 502, 503, and 504 are lists each storing cells. The list shown here is
A data structure used to store elements having an order relationship, consisting of a pointer to the first element in the list, a pointer to the last element in the list, and elements to be stored in the list. Information and a pointer to the next element. For example, 505 is a list 1 (50
2) The tail element, 506, is the head element of list 1 (502).

In FIG. 18, the information of the element stored in the list is a cell. Reference numeral 507 denotes a transmission list for storing cells whose transmission time has reached.

The conventional shaper 200 using the GCRA method
The operation of the cell transmitting means 204 will be described by a calendar method.

In the calendar system, the time required to transfer several cells on a line is defined as one time slot. As shown in FIG. 18, a list for storing cells corresponding to the time slots is arranged in a ring, and the transmission possible time is set. In this method, all cells stored in the list corresponding to the reached time slot are moved to the end of the transmission list. Specifically, in FIG. 18, the list indicated by the pointer 501 indicating the list corresponding to the current time stores cells corresponding to the time slot at the current time. Here, the time normalized by the time required for one time slot, that is, (time / time required for one time slot) is referred to as a normalized time, and the normalized current time in FIG. Assuming that the number is N, the list on the right side of this list stores cells whose transmission possible time is the normalized time t + 1, and the list on the left side is the normalized time t + N-1.

The pointer 501 indicating the list corresponding to the current time is updated based on the time counted by the clock means 202. When the cell arrives at the shaper 200, the calendar sequentially adds the arriving cells as elements of the list to the end of the list of time slots corresponding to the transmittable times of the cells determined by the scheduling means 203, and stores them. , The arrival cell and the transmittable time are stored as a pair.

The calendar moves all the cells stored in the list corresponding to the time slot at which the transmittable time has been reached, indicated by the pointer 501 indicating the list corresponding to the current time, to the end of the transmit list, The cells stored in the cell are transmitted to the line in order from the top, and the cells whose transmittable time is before the current time are detected from the cells stored in the calendar, and the cells whose transmittable time is the earliest are transmitted. Send to the line in order of possible time.

The shaper 200 according to the conventional GCRA system
A third operation example of the cell transmission means 204 will be described. FIG. 19 is a diagram showing an implementation example of the cell transmission means 204 in FIG. 15, and is generally called a sequencer system. See, for example, Jonathan Chao, "A Genera
l Architecture for Link-Layer Congestion Control i
n ATM Networks, "ISS 1992, Oct. 1992.

Referring to FIG. 19, 601 and 602 are buffers for storing cells, 603 is a pointer to a buffer for storing cells, 604 is a time slot value corresponding to a cell transmittable time, and 605 is a pointer and a time slot value. 606 is a buffer for storing an arriving cell, 607 is a pointer to a buffer for storing an arriving cell, 608 is a time slot value corresponding to the transmittable time of the arriving cell, and 609 is a broadcast bus. .

The shaper 200 according to the conventional GCRA system
The operation of the cell transmission means 204 will be described by a sequencer method. In the sequencer method, the time required for transferring one cell on a line is defined as one time slot, and as shown in FIG. 19, a cell whose transmission possible time is determined is stored in a buffer, and a pointer to a buffer for storing the cell and a pointer to the buffer. This is a method in which elements consisting of time slot values corresponding to the transmittable times of cells are sorted in order of time slot values.

The sequencer system has an array structure mainly composed of a pointer and a time slot value.
In the example shown in (1), the elements are sorted in the order of transmission possible time from the right side. Specifically, in FIG. 19, each element of the array structure 605 having a pointer and a time slot value as elements is a structure that can be shifted to an adjacent element.
When a cell arrives at the shaper 200, the sequencer
A cell is stored in a buffer 606 for storing an arriving cell, a pointer 607 to a buffer for storing an arriving cell is set to indicate this buffer, and a time slot corresponding to the transmittable time of the cell determined by the scheduling means 203 is set. Is set to the time slot value 608 corresponding to the transmittable time of the arriving cell, so that the arriving cell and the transmittable time are stored as a pair.

Next, in the sequencer system, a time slot value 608 corresponding to the transmittable time of the arriving cell is calculated as follows:
Using the broadcast bus 609, the time slot value of each element in the array structure 605 is compared in parallel with the time slot value of each element in the array structure 605 having the pointer and the time slot value as elements. The position of the first element after the time slot value 608 corresponding to the possible time is set as the insertion position, all the elements after that are shifted to the left, a pointer 607 to a buffer for storing the arriving cell and the pointer of the arriving cell By storing the time slot value 608 corresponding to the transmittable time at the insertion position, the elements are sorted in the transmittable time order.

In the sequencer system, the time slot value of the rightmost element of the array structure 605 is compared with the time slot value corresponding to the time counted by the clock means 202. If the latter value is earlier than the former value, , Transmitting the cell stored in the buffer indicated by the pointer of the rightmost element to the line,
By deleting the rightmost element from the array structure 605 and shifting the remaining elements to the right, a cell whose transmittable time is earlier than the current time is detected from the cells stored in the sequence, and the transmittable time is detected. Transmit to the line in the order of the transmittable time from the earliest cell.

As is clear from the above, the transmission timing generating means 10 of the shaper 100 using the conventional token system
Nos. 4,105 generate timing signals indicating that the head cell of the queue can be transmitted by a clock signal based on the traffic characteristic value for each connection.

The shaper 2 of the conventional GCRA type
The scheduling means 204 of 00 has determined the transmittable time according to the connection when the cell arrives at the shaper, and has updated the parameters based on the determined transmittable time.

Therefore, when the timing and the time at which a plurality of connections can be transmitted become the same, a timing signal indicating that the head cell of the queue has become transmittable is transmitted to the shaper 100 of the conventional token system. There is a possibility that a delay time is generated from the generation of the cell to the timing at which the cell is actually transmitted.

The conventional GCRA type shaper 20
In the case of 0, there is a possibility that a delay time is generated from the transmission possible time of the cell to the time at which the cell is actually transmitted, and when shaping is performed on many connections, these delay times cannot be ignored. Can be a value. For example, in a shaper performing shaping on 4096 connections, when the transmission timing and the transmittable time of 512 connections are the same, the worst value of the generated delay time is 511 cell times. here,
One cell time is the time required for transferring one cell on a line (about 2.7 μsec for an STM-1 / STS-3c line).

On the other hand, the transmission timing generation means 104 and 105 of the shaper 100 according to the conventional token method start from the generation of a timing signal indicating that the head cell of the queue can be transmitted, to the timing at which the cell is actually transmitted. , The timing signal is generated based on the clock signal based on the traffic characteristic value for each connection.

Further, the scheduling means 203 of the shaper 200 according to the conventional GCRA method determines a transmittable time according to the connection when the cell arrives at the shaper, and the cell is actually transmitted from the transmittable time of the cell. The parameter is updated based on the determined transmission possible time regardless of the delay time between the times.

To summarize the above, a conventional shaper has
Although there is a possibility that a delay time may occur between the timing or time when a cell belonging to a connection becomes available for transmission and the timing or time when a cell is actually transmitted, the transmission timing generation means or the scheduling means may be used. The method does not consider this delay time.

For this reason, if there is a cell waiting for the timing or time at which transmission can be continued in a connection in which a delay time has occurred, the cell in which the delay has occurred and the transmission interval of this cell will be This causes a problem that the fluctuation of the cell delay time may exceed an allowable value. For example, when the transmission timing and the transmittable time of 512 connections are the same in a shaper that performs shaping on 4096 connections, the delay time of these connections is 0 to 511 cell times.

On the other hand, if the value of the fluctuation of the cell delay time allowed in the connection is 256 cell times, if there is a cell waiting for the timing or time when transmission can be continued in the connection where the delay time has occurred. In addition, the fluctuation of the cell delay time may exceed the allowable value. This problem is known as a problem of clamping in the shaper.

The shaper 200 according to the conventional GCRA system
A solution to the clamping in the scheduling means 203 will be described. FIG. 20 is a flowchart showing an operation example of the scheduling means 203 of FIG. 15, and it is assumed that a ring buffer method is used as the cell transmission means 204. About this, for example, Fabrice Guillemin, Pierre Boyer, Luc Romoeu
f, "The Spacer-Controller: Architecture and First
Assesments, "Proc. Of the IFIP TC6 Workshopon Broa
dband Communications, Jan. 1992.

In the flow chart shown in FIG. 20, the value of the cell interval and the permissible fluctuation of the cell delay time are used as the traffic characteristic values, the current time when calculating the transmittable time of the cell is ta, and the cell belongs. The cell interval value of the traffic characteristic value corresponding to the connection is T, the allowable cell delay time fluctuation value is τ, the parameter value corresponding to the connection to which the cell belongs is LRT, the transmittable time of the cell is ts, the ring The time corresponding to the time slot of the buffer in which the cell is stored in the buffer is represented by te.

The shaper 200 according to the conventional GCRA system
As shown in FIG. 20, when the cell arrives at the shaper, the scheduling means 203 first calculates the cell interval value T, which is the traffic characteristic value corresponding to the connection to which this cell belongs, and the allowable cell delay time. Τ and the parameter value LRT are input.

The scheduling means 203 performs the processing shown in the flowchart of FIG. 20 on the basis of the input cell interval value T, the allowable cell delay time fluctuation τ, the parameter value LRT, and the current time ta counted by the clock means 202. Initiate the indicated action.

First, the value of ts is set to LRT + T (step 701). Next, when the relationship of ts <ta is established, the value of ts is set to ta (steps 702 and 703),
When the relationship of ts <ta is not established, ts> ta + τ
Is established, the cell is discarded (step 70).
2, 704, 705), when the relationship ts <ta is not established, and when the relationship ts> ta + τ is not established, t
The value of s is not changed (steps 702 and 704).

The determined transmittable time ts of the cell is output to the cell transmitting means 204 realized by the ring buffer method.

The cell transmission means 204 realized by the ring buffer system is configured such that, when the buffer of the time slot corresponding to ts is empty, another cell is already stored in the buffer of the time slot corresponding to ts. If so, the cell is stored in the buffer of the subsequent time slot, the time te corresponding to the time slot of the buffer in which the cell is stored is returned to the scheduling means 203, and the value of LRT is updated to te (step 706). .
The updated parameter value LRT is a means 201 for storing a traffic characteristic value and a parameter value for each connection.
And the stored parameter values are updated.

The scheduling means 203 based on the above algorithm updates the value of the parameter based on the time when the cell is actually transmitted, so that the time between the time when the cell can be transmitted and the time when the cell is actually transmitted is updated. Since the delay time is taken into consideration, the problem of clamping in the shaper according to the conventional GCRA method can be solved.

However, this scheduling means 203
Uses the property that the time at which a cell is actually transmitted when the cell is stored in the ring buffer method is used, so that the cell is actually transmitted when the cell is stored, such as the calendar method or the sequencer method. It cannot be used in combination with a cell transmitting means having the property that the time is not determined.

In the ring buffer system, the time slot for transmitting a cell is determined to be the first empty slot after the transmittable time, so that the cell that arrives at the ring buffer earlier at the transmittable time arrives later. There is a possibility that the cells are stored in the time slot before the cell with the earliest possible transmission time, and the cells actually transmitted are not always in the order of the possible transmission times, and the transmission order of the cells may be reversed.

On the other hand, the cell transmission means 2 of the calendar system
No. 04 sequentially adds cells to the end of the list of time slots corresponding to transmittable times and stores them.

The cell transmitting means 204 of the sequencer system sorts elements consisting of a pointer to a buffer for storing a cell and the transmittable time of the cell in order of transmittable time. The transmitted cells are always in the order of the transmittable time, and there is no possibility that the transmission order of the cells is reversed.

For this reason, the scheduling means 203 based on the above algorithm is based on the premise that the ring buffer method is used as the cell transmission means 204, and the transmission order of cells may be reversed.

A method for solving the clamping in the transmission timing generating means 104 and 105 of the conventional token type shaper 100 is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 9-130398. The transmission timing generation means 104 and 105 in the example of realizing the conventional token type shaper 100 shown in FIG. 14 correspond to the cell transmission request means and the connection management means in the above publication.

The arbitration means 106 corresponds to the cell multiplexing control means and the cell transmission means in the above publication. The cell multiplexing control means in the above publication includes a contention result transmitting section for returning contention result information indicating selection or non-selection of a cell transmission request signal to the corresponding cell transmission request means.

The cell transmission request means delays the next cell transmission request timing by the cell transfer interval when the transmitted contention result information indicates that the cell transmission request signal transmitted by itself has lost in the contention control. Means for operating the value of the cell transmission count time.

For this reason, in the implementation example of the token type shaper 100 in the above-mentioned publication, the timing at which a plurality of connections can be transmitted becomes the same, and at the same time, a cell transmission request signal is transmitted from a plurality of cell transmission request means to a cell multiplex control means. And the cell transmission request means delays the next cell transmission request timing by the cell transfer interval even if a delay time occurs between the generation of the cell transmission request signal and the actual transmission of the cell as a result of the contention control. Thus, the delay time can be considered.

[0072]

In the above-mentioned conventional method of solving clamping in a shaper realized by the GCRA method, it is assumed that a ring buffer method is used as cell transmission means.

However, in the ring buffer method, the time slot for transmitting a cell is determined to be the first empty slot after the transmittable time, so that the cell having arrived at the ring buffer and having a later transmittable time has a later time. There is a possibility that the transmitted cell may be stored in the time slot before the cell with the earliest possible transmission time, and the cells actually transmitted are not always in the transmission possible time order, and the transmission order of the cells is reversed. there were.

Further, the conventional method of solving clamping in the shaper realized by the GCRA system utilizes the property of the ring buffer system in which the time at which a cell is actually transmitted is determined when the cell is stored. It cannot be used in combination with a cell transmission means that uses a calendar method or a sequencer method that can suppress the inversion of the cell transmission order and has a property that the time at which a cell is actually transmitted when the cell is stored is not determined.

The conventional token-based shaper can solve the problem of clamping without inverting the transmission order of the cells. However, as described in the above-mentioned prior art, the shaper of the cell is used for each connection. The token method that realizes the shaper by generating the timing at which transmission is possible, and the transmittable time of the cell is calculated for each connection, and the transmittable time is before the current time based on the current time counted by the clock means The GCRA method of detecting a cell to be transmitted and transmitting the cell to a line is a method whose operation principle is fundamentally different.

For this reason, the solution to the clamping problem in the token-type shaper cannot be applied to the GCRA-type shaper.

As described above, the shaper realized by the conventional GCRA system has a problem that it is not possible to simultaneously solve the clamping problem and suppress the inversion of the cell transmission order.

The present invention has been made to solve this problem, and an object of the present invention is to provide a GCRA shaping device which solves the clamping problem and suppresses the reversal of the cell transmission order. Is to do.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0080]

The outline of the invention disclosed in the present application is briefly described as follows.

(1) Storage means for storing traffic characteristic values and parameter values for each connection, clock means for counting the current time, and the traffic characteristic values, parameter values, And scheduling means for determining the transmittable time of the cell based on the current time counted by the clock means and updating the parameter value, and the clock means from the cell for which the transmittable time is determined by the scheduling means. Based on the current time to count, the transmittable time detects a cell before the current time, and a cell transmitting means for transmitting the cell to the line, a cell shaping apparatus, wherein each connection A queue for storing cells in the order of arrival from the top, and the cells to which the cells have arrived belong. Input means for storing in a queue corresponding to the connection, wherein the scheduling means calculates and determines a transmittable time of the cell when a cell stored in the queue reaches the head of the queue. And, when the cell transmitting means transmits a cell to the line, comprising means for updating a parameter value corresponding to the connection to which the cell belongs, the cell transmitting means,
A means for detecting a cell whose transmittable time determined by the scheduling means is before a current time, extracting a cell having the earliest transmittable time from the head of the queue, and transmitting the cell to the line.

(2) In the cell shaping device of (1), the current time when calculating the cell transmittable time is t
a, the current time when updating the parameter value is te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs is T, the value of the allowable cell delay time fluctuation is τ, and the cell is The parameter value corresponding to the connection to which it belongs is TAT, and the transmittable time of the cell is t.
s, the scheduling means calculates the transmission possible time ts of the cell as TAT-T when calculating the transmission possible time ts of the cell, when the relation of ta <TAT-τ holds.
When the relation of TAT−τ ≦ ta is established, the transmittable time ts of the cell is determined as ta. When the parameter value TAT is updated, when the relation of te <TAT holds, Means is provided for updating the value TAT to TAT + T and updating the parameter value TAT to te + T when the relationship of TAT ≦ te holds.

(3) In the cell shaping device of (1), the current time when calculating the cell transmittable time is t
a, the current time when updating the parameter value is te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs is T, the value of the allowable cell delay time fluctuation is τ, and the cell is The parameter value corresponding to the connection to which it belongs is TAT, and the transmittable time of the cell is t.
s, when calculating the transmittable time ts of the cell, if the relation of ta ≦ TAT−τ is satisfied, the scheduling means sets the transmittable time ts of the cell to TAT−
When the relationship of TAT−τ <ta is established, the transmittable time ts of the cell is determined as ta. When the parameter value TAT is updated, when the relationship of te ≦ TAT is established, Means for updating the value TAT to TAT + T and updating the parameter value TAT to te + T when the relationship of TAT <te holds.

(4) In the cell shaping device of (1), the current time when calculating the cell transmittable time is t
a, the current time when updating the parameter value is te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs is T, the value of the allowable cell delay time fluctuation is τ, and the cell is The parameter value corresponding to the connection to which it belongs is TET, and the transmittable time of the cell is t.
When s is set, the scheduling unit sets the transmission possible time ts of the cell to TET when the relation of ta <TET is satisfied when calculating the transmission possible time ts of the cell,
When the relationship of TET ≦ ta is established, the transmittable time ts of the cell is determined as ta, and when the parameter value TET is updated, the parameter value TET is changed to TET + T when the relationship of te <TET + τ is established. Update and TE
When the relation of T + τ ≦ te is satisfied, a means for updating the parameter value TET to te−τ + T is provided.

(5) In the cell shaping device of (1), the current time when calculating the cell transmittable time is t
a, the current time when updating the parameter value is te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs is T, the value of the allowable cell delay time fluctuation is τ, and the cell is The parameter value corresponding to the connection to which it belongs is TET, and the transmittable time of the cell is t.
When s is set, the scheduling means sets the transmission possible time ts of the cell to TET when the relation of ta ≦ TET is satisfied when calculating the transmission possible time ts of the cell,
When the relationship of TET <ta is established, the transmittable time ts of the cell is determined as ta, and when the parameter value TET is updated, the parameter value TET is changed to TET + T when the relationship of te ≦ TET + τ is established. Update and TE
When the relation of T + τ <te holds, there is means for updating the parameter value TET to te−τ + T.

As described above, the cell shaping apparatus of the present invention has a queue for storing cells in the order of arrival from the top for each connection, and stores the arrived cell in the queue corresponding to the connection to which the cell belongs. Means, when the cell stored in the queue reaches the head of the queue, the scheduling means determines the transmittable time of the cell, and the cell transmitting means determines the cell whose transmittable time is before the current time. Upon detection, the cell with the earliest possible transmission time is taken out of the head of the queue and transmitted to the line, and when the cell transmitting unit transmits the cell to the line, the scheduling unit corresponds to the connection to which the cell belongs. In order to update the parameter value, the time from when the cell belonging to a certain connection becomes available for transmission Even if a delay time occurs, the parameter value is updated based on the time when the cell is actually transmitted, so that the delay between the time when the cell can be transmitted and the time when the cell is actually transmitted is updated. Considering time, it is possible to solve the problem of clamping.

When the cell stored in the queue reaches the head of the queue, the scheduling means determines the transmittable time of the cell, and the cell transmitting means determines the cell whose transmittable time is before the current time. Upon detection, the cell with the earliest possible transmission time is taken out of the head of the queue and transmitted to the line, and when the cell transmitting unit transmits the cell to the line, the scheduling unit corresponds to the connection to which the cell belongs. By updating the parameter values,
When a cell is stored in the queue, it does not determine the time at which the cell is actually transmitted, so the cell transmitting means can transmit the cells in the transmittable time order, and the cells caused by the cells not being sorted in the transmittable order. Can be suppressed from being reversed.

[0088]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the configuration of a cell shaping device (shaper) according to one embodiment of the present invention.

As shown in FIG. 1, a shaper 800 according to an embodiment of the present invention includes a storage unit 801 for storing traffic characteristic values and parameter values, a clock unit 802 for counting the current time, a cell transmission available time. A scheduling unit 803 for determining parameters and updating parameter values, a cell transmitting unit 804 for transmitting cells, queues 805 and 806 provided for each connection for transmitting cells, and inputting cells from the connections to the queues 805 and 806 Input section 8
07.

Next, the operation of the shaper 800 of this embodiment will be described in detail.

The storage unit 801 is a storage unit for storing traffic characteristic values and parameter values for each connection, and is configured in an array addressed by a connection identifier value. Here, the connection means a virtual path or channel identified by part or all of the VPI and VCI fields included in the cell header.

As shown in FIG. 1, a cell arriving at the shaper 800 is stored by an input unit 807 in a queue 805, 806 or the like corresponding to the connection to which the cell belongs.

The queues 805 and 806 store cells in the order of arrival from the top, and are provided independently for each connection. When the cell reaches the head of the queue, these values corresponding to the connection of the cell that has reached the head of the queue are input to the scheduling unit 803 from the storage unit 801 that stores the traffic characteristic values and parameter values for each connection. You.

The scheduling unit 803 determines the transmittable time of the cell that has reached the head of the queue based on the input traffic characteristic values, parameter values, and the current time counted by the clock unit 802, and determines the cell transmission unit 804 Output to

[0096] Cell transmitting section 804 stores, as a pair, pointer information to the head cell of the queue and the transmittable time of the cell determined by scheduling section 803.

The cell transmission unit 804 detects the pointer information of the cell whose transmission possible time is before the current time based on the current time counted by the clock unit 802, and transmits the cell indicated by the pointer from the head of the queue. Take out in order of possible time and send to line. When a cell is transmitted to a line, these values corresponding to the connection of the cell to be transmitted are input to the scheduling unit 803 from the storage unit 801 that stores the traffic characteristic values and parameter values for each connection.

The scheduling unit 803 determines an updated value of the parameter value based on the input traffic characteristic value, parameter value, and current time counted by the clock unit 802, and determines the traffic characteristic value, parameter value for each connection. Is output to the storage unit 801 which stores the parameter value, and the stored parameter value is updated.

A storage unit 801 for storing traffic characteristic values and parameter values and a clock unit 802 are provided by a conventional GCR.
A storage means for storing parameter values of the shaper according to the A method and a clock means are used.
6. Since the input unit 807 uses a queue of a shaper and input means based on the conventional token method, a description of its operation is omitted.

Next, the scheduling unit 8 of the present embodiment
The operation of Step 03 will be described with reference to FIGS. 2 and 3 are flowcharts showing an operation example of the scheduling unit.

First, when a cell reaches the head of the queue,
When these values corresponding to the connection of the cell that has reached the head of the queue are input to the scheduling unit 803 from the storage unit 801 that stores the traffic characteristic values and parameter values for each connection, the input traffic characteristic values, The following operation shown in the flowchart of FIG. 2 is started based on the parameter value and the current time counted by the clock unit 802.

The scheduling unit 803 uses the conventional GC
In accordance with the operation of the shaper scheduling means by the RA method, the transmittable time of the cell is determined (step 90).
1), the determined transmittable time of the cell is output to the cell transmitter 804.

When a cell is transmitted to a line, these values corresponding to the connection of the cell to be transmitted are input to the scheduling unit 803 from the storage unit 801 storing the traffic characteristic value and parameter value for each connection.

The scheduling unit 803 starts the following operation shown in the flowchart of FIG. 3, based on the input traffic characteristic value, parameter value, and current time counted by the clock unit 802.

[0105] The scheduling unit 803 uses the conventional GC
An update value of the parameter value is determined according to the operation of the shaper scheduling means by the RA method (step 1).
001), the determined updated parameter value is output to the storage unit 801 that stores the traffic characteristic value and the parameter value for each connection, and the stored parameter value is updated.

Next, the cell transmitting section 804 of the present embodiment will be described. FIG. 4 is a diagram showing an example in which a cell transmission unit using a conventional calendar method is applied as a cell transmission unit 804 of a shaper 800 according to the present embodiment. It was done.

In FIG. 4, reference numeral 1101 denotes a pointer indicating a list corresponding to the current time;
Reference numeral 04 denotes a list for storing a pointer to the head cell of each queue. Reference numeral 1107 denotes a transmission list for storing a pointer to the head cell of the queue that has reached the transmittable time.

[0108] As shown in FIG.
The time required to transfer several cells on the line is defined as one time slot, and a list for storing pointers to cells corresponding to the time slots is arranged in a ring, and stored in a list corresponding to the time slot at which transmission is possible. Move the pointers to all cells to the end of the transmission list.

More specifically, in FIG. 4, the list indicated by pointer 1101 indicating the list corresponding to the current time is:
The pointer to the cell corresponding to the time slot of the current time is stored.

The pointer 1101 indicating the list corresponding to the current time is updated based on the time counted by the clock unit 802.

[0111] As shown in FIG.
When the cell reaches the head of the queue, a pointer to the cell at the head of the queue is sequentially added as an element of the list to the end of the list of the time slots corresponding to the transmittable time of the cell determined by the scheduling unit 803. By storing, the pointer to the cell at the head of the queue and the transmittable time are stored as a pair.

[0112] As shown in FIG.
All pointers to the cells stored in the list corresponding to the time slot that has reached the transmittable time indicated by the pointer 1101 indicating the list corresponding to the current time are moved to the end of the transmission list, and the cells stored in the transmission list are moved. By extracting the cell indicated by the pointer to the cell from the head of the queue and transmitting it to the line in order, the pointer to the cell whose transmittable time is earlier than the current time is detected from the pointers to the stored cells. Then, the cell indicated by the pointer is transmitted to the line in the order of the transmittable time from the cell with the earliest transmittable time.

Next, the cell transmitting section 80 of the above-described embodiment is described.
A second example of the fourth implementation will be described with reference to FIG. In the second implementation example, a cell transmission unit using a conventional sequencer method is replaced with a cell transmission unit 804 of a shaping apparatus 800.
In this case, the pointer to the buffer storing the cell is used as the pointer to the cell at the head of the queue.

In FIG. 5, reference numerals 1201 and 1202 denote queues; 1203, a pointer to the head cell of the queue;
04 is a time slot value corresponding to the transmittable time of the head cell of the queue, 1205 is an array structure having pointer and time slot value as elements, 1206 is a queue, 1207
Is a pointer to the cell that has reached the head of the queue, 1208 is a time slot value corresponding to the transmittable time of the cell that has reached the head of the queue, and 1209 is a broadcast bus, respectively.

In the second implementation example of the cell transmission unit 804, as shown in FIG. 5, the time required to transfer one cell on the line is set to one time slot, and the time at which the transmission is possible is determined. , And an element consisting of a time slot value corresponding to the transmittable time of the cell is sorted in the order of the time slot value.

More specifically, in FIG. 5, each element of the array structure 1205 having a pointer and a time slot value as elements can be shifted to the next element.

In the second implementation example of the cell transmission unit 804 shown in FIG. 5, when a cell reaches the head of the queue 1206, a pointer 1207 to the cell that has reached the head of the queue to indicate the head of the queue. And the scheduling unit 8
By setting the value of the time slot corresponding to the transmittable time of the cell determined by step 03 to the time slot value corresponding to the transmittable time of the cell that has reached the head of the queue of 1208, a pointer to the cell at the head of the queue is set. And the transmittable time are stored as a pair.

Next, the cell transmission unit 804 shown in FIG.
In the implementation example, the time slot value 1208 corresponding to the transmittable time of the cell that has reached the head of the queue is converted into the time slot value of each element in the array structure 1205 using the pointer and the time slot value as elements using the broadcast bus 1209. The position of the first element in which the time slot value of each element in the array structure 1205 is equal to or later than the time slot value 1208 corresponding to the transmittable time of the cell reaching the head of the queue is set as the insertion position. , By shifting all elements thereafter to the left, and storing the pointer 1207 to the cell that has reached the head of the queue and the time slot value 1208 corresponding to the transmittable time of the cell that has reached the head of the queue at the insertion position. , The elements are sorted in order of transmission time.

In the second implementation example of the cell transmission unit 804 shown in FIG. 5, the time slot value of the rightmost element of the array structure 1205 is compared with the time slot value corresponding to the time counted by the clock unit 802. If the latter value is earlier than the former value, the cell stored at the head of the queue indicated by the pointer of the rightmost element is transmitted to the line, the rightmost element is deleted from the array structure 1205, and the remaining elements are deleted. Is shifted to the right, a pointer to a cell whose transmittable time is earlier than the current time is detected from among the pointers to the stored cells, and the cell indicated by the pointer is transmitted from the cell whose transmittable time is the earliest. Send to the line in the order of possible transmission time.

Next, the processing of the scheduling unit 803 in the shaping apparatus 800 of the first embodiment is as follows.
Although the processing in the scheduling means of the conventional GCRA method has been applied, the present invention is not limited to this. For example, the scheduling unit 803 may be realized by the processing described in each of the following embodiments.

(Embodiment 1) FIGS. 6 and 7 are flowcharts showing the processing of the scheduling unit 803 of Embodiment 1 of the present invention. Hereinafter, the operation of the scheduling unit 803 of the first embodiment will be described with reference to the flowcharts of FIGS.

In these flowcharts, the cell time value and the allowable cell delay time fluctuation are used as traffic characteristic values, the current time when calculating the cell transmittable time is ta, and the parameter value is updated. Te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs, T, the value of the permissible fluctuation of the cell delay time, τ, and the parameter value corresponding to the connection to which the cell belongs. The transmission possible time of the TAT and the cell is represented by ts.

The scheduling unit 803 of the first embodiment
Is a storage unit 8 for storing a traffic characteristic value and a parameter value for each connection when a cell reaches the head of the queue.
01, the cell interval value T which is the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue, the allowable cell delay time fluctuation τ, and the parameter value TAT are input. The following operation shown in the flowchart in FIG. 6 is started based on the interval value T, the allowable cell delay time fluctuation τ, the parameter value TAT, and the current time ta counted by the clock unit 802.

If the relationship of ta <TAT-τ is satisfied, the transmittable time ts of the cell is set to TAT-τ (steps 1301 and 1303).

When the relationship of TAT−τ ≦ ta is established, the cell transmittable time ts is set to ta (step 1).
301, 1302). Possible transmission time ts of the determined cell
Is output to the cell transmission unit 804.

When a cell is transmitted to the line, the storage unit 801 for storing the traffic characteristic value and parameter value for each connection reads the cell interval of the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue. Value T and allowable cell delay time fluctuation τ, parameter value TA
T is input to the scheduling unit 803 of the first embodiment.

The scheduling unit 803 of the first embodiment
Are input cell interval value T, allowable cell delay time fluctuation τ, parameter value TAT, and clock section 802.
The following operation shown in the flowchart of FIG. 7 is started based on the current time te counted by.

If the relationship te <TAT holds, the parameter value TAT is updated to TAT + T (steps 1401 and 1403).

If the relationship of TAT ≦ te holds, the parameter value TAT is updated to te + T (step 1).
401, 1402). Update value T of the determined parameter value
The AT is output to a storage unit 801 that stores traffic characteristic values and parameter values for each connection, and the stored parameter values are updated.

The scheduling unit 8 of the first embodiment
03 is applicable to a shaper that uses only the cell interval value as a traffic characteristic value by replacing the fluctuation value τ of the cell delay time in the above algorithm with a fixed value such as 0 or a constant.

(Embodiment 2) FIGS. 8 and 9 are flowcharts showing the processing of the scheduling unit 803 of Embodiment 2 of the present invention. Hereinafter, the operation of the scheduling unit 803 of the second embodiment will be described with reference to the flowcharts of FIGS.

Note that the scheduling unit 8 of the second embodiment
03 is different from the scheduling unit 803 of the first embodiment, but performs the same operation logically.

In these flowcharts, the current time when calculating the cell transmittable time is ta, and the parameter value is updated, using the value of the cell interval and the fluctuation of the allowable cell delay time as the traffic characteristic value. Te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs, T, the value of the permissible fluctuation of the cell delay time, τ, and the parameter value corresponding to the connection to which the cell belongs. The transmission possible time of the TAT and the cell is represented by ts.

The scheduling unit 803 of the second embodiment
Is a storage unit 8 for storing a traffic characteristic value and a parameter value for each connection when a cell reaches the head of the queue.
01, the cell interval value T which is the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue, the allowable cell delay time fluctuation τ, and the parameter value TAT are input. The following operation shown in the flowchart of FIG. 8 is started based on the interval value T, the allowable cell delay time fluctuation τ, the parameter value TAT, and the current time ta counted by the clock unit 802.

If the relationship of ta ≦ TAT-τ is satisfied, the cell transmission available time ts is set to TAT-τ (steps 1501 and 1503).

If the relationship of TAT−τ <ta is satisfied, the cell transmittable time ts is set to ta (step 1).
501, 1502). Possible transmission time ts of the determined cell
Is output to the cell transmission unit 804.

When a cell is transmitted to the line, the storage unit 801 for storing the traffic characteristic value and parameter value for each connection stores the cell interval of the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue. Value T and allowable cell delay time fluctuation τ, parameter value TA
T is input to the scheduling unit 803 of the second embodiment.

The scheduling section 803 of the second embodiment
Are input cell interval value T, allowable cell delay time fluctuation τ, parameter value TAT, and clock section 802.
The following operation shown in the flowchart of FIG. 9 is started based on the current time te counted by.

If the relationship te ≦ TAT holds, the parameter value TAT is updated to TAT + T (steps 1601 and 1603).

If the relationship of TAT <te holds, the parameter value TAT is updated to te + T (step 1).
601 and 1602). Update value T of the determined parameter value
The AT is output to a storage unit 801 that stores traffic characteristic values and parameter values for each connection, and the stored parameter values are updated.

The scheduling unit 8 of the second embodiment
03 is also applicable to a shaper that uses only the value of the cell interval as the traffic characteristic value by replacing the fluctuation value τ of the cell delay time in the above algorithm with a fixed value such as 0 or a constant.

(Embodiment 3) FIGS. 10 and 11 are flowcharts showing the processing of the scheduling unit 803 of Embodiment 3 of the present invention. Hereinafter, the scheduling unit 803 of the third embodiment will be described with reference to the flowcharts of FIGS.
The operation of will be described.

The scheduling unit 8 of the third embodiment
03 is different from the scheduling unit 803 of the first embodiment, but performs the same operation logically.

In these flowcharts, the current time when calculating the transmittable time of the cell is ta, and the parameter value is updated using the value of the cell interval and the fluctuation of the allowable cell delay time as the traffic characteristic value. Te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs, T, the value of the permissible fluctuation of the cell delay time, τ, and the parameter value corresponding to the connection to which the cell belongs. TET and the transmission available time of the cell are represented by ts.

The scheduling unit 803 of the third embodiment
Is a storage unit 8 for storing a traffic characteristic value and a parameter value for each connection when a cell reaches the head of the queue.
01, the cell interval value T which is the traffic characteristic value corresponding to the connection of the cell reaching the head of the queue, the allowable cell delay time fluctuation τ, and the parameter value TET are input. The following operation shown in the flowchart of FIG. 10 is started based on the interval value T, the allowable cell delay time fluctuation τ, the parameter value TET, and the current time ta counted by the clock unit 802.

If the relation of ta <TET is established, the transmission possible time ts of the cell is set to TET (step 170).
1, 1703).

If the relationship of TET ≦ ta is satisfied, the cell transmittable time ts is set to ta (step 170).
1, 1702). The determined transmission possible time ts of the cell is:
Output to cell transmission section 804.

When a cell is transmitted to the line, the storage unit 801 for storing the traffic characteristic value and parameter value for each connection reads the cell interval, which is the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue. The value T, the value τ of the allowable cell delay time fluctuation, and the parameter value TET are input to the scheduling unit 803 of the third embodiment.

The scheduling unit 803 of the third embodiment
Are input cell interval value T, allowable cell delay time fluctuation τ, parameter value TET, and clock section 802.
The following operation shown in the flowchart of FIG. 11 is started based on the current time te counted by.

If the relationship te <TET + τ is satisfied, the parameter value TET is updated to TET + T (steps 1801 and 1803).

If the relationship of TET + τ ≦ te holds, the parameter value TET is updated to te−τ + T (steps 1801 and 1802). The determined updated value TET of the parameter value is output to the storage unit 801 that stores the traffic characteristic value and the parameter value for each connection,
The stored parameter value is updated.

The scheduling unit 8 of the third embodiment
03 is also applicable to a shaper that uses only the value of the cell interval as the traffic characteristic value by replacing the fluctuation value τ of the cell delay time in the above algorithm with a fixed value such as 0 or a constant.

(Embodiment 4) FIGS. 12 and 13 show Embodiment 4 of the present invention.
7 is a flowchart showing the processing of the scheduling unit 803. Hereinafter, the operation of the scheduling unit 803 of the third embodiment will be described with reference to the flowcharts of FIGS.

The scheduling unit 8 of the fourth embodiment
03 is different from the scheduling unit 803 of the first embodiment, but performs the same operation logically.

In these flowcharts, the value of the cell interval and the permissible fluctuation of the cell delay time are used as the traffic characteristic values, the current time at which the transmittable time of the cell is calculated is ta, and the parameter value is updated. Te, the value of the cell interval of the traffic characteristic value corresponding to the connection to which the cell belongs, T, the value of the permissible fluctuation of the cell delay time, τ, and the parameter value corresponding to the connection to which the cell belongs. TET and the transmission available time of the cell are represented by ts.

The scheduling unit 803 of the fourth embodiment
Is a storage unit 8 for storing a traffic characteristic value and a parameter value for each connection when a cell reaches the head of the queue.
01, the cell interval value T which is the traffic characteristic value corresponding to the connection of the cell reaching the head of the queue, the allowable cell delay time fluctuation τ, and the parameter value TET are input. The following operation shown in the flowchart of FIG. 12 is started based on the interval value T, the allowable cell delay time fluctuation τ, the parameter value TET, and the current time ta counted by the clock unit 802.

If the relationship of ta ≦ TET is established, the transmission enabled time ts of the cell is set to TET (step 190).
1, 1903).

If the relationship of TET <ta holds, the cell transmission enable time ts is set to ta (step 190).
1, 1902). The determined transmission possible time ts of the cell is:
Output to cell transmission section 804.

When a cell is transmitted to a line, a unit 8 for storing a traffic characteristic value and a parameter value for each connection.
From 01, the value T of the cell interval, which is the traffic characteristic value corresponding to the connection of the cell that has reached the head of the queue, the allowable cell delay time fluctuation τ, and the parameter value TET are input to the scheduling unit 803 of the fourth embodiment. Is done.

The scheduling unit 803 of the third embodiment
Are input cell interval value T, allowable cell delay time fluctuation τ, parameter value TET, and clock section 802.
The following operation shown in the flowchart of FIG. 13 is started on the basis of the current time te counted by.

If the relationship te ≦ TET + τ is satisfied, the parameter value TET is updated to TET + T (steps 2001 and 2003).

If the relationship of TET + τ <te holds, the parameter value TET is updated to te−τ + T (steps 2001 and 2002). The determined updated value TET of the parameter value is output to the storage unit 801 that stores the traffic characteristic value and the parameter value for each connection,
The stored parameter value is updated.

The scheduling unit 8 of the fourth embodiment
03 is also applicable to a shaper that uses only the value of the cell interval as the traffic characteristic value by replacing the fluctuation value τ of the cell delay time in the above algorithm with a fixed value such as 0 or a constant.

As described above, the cell shaping apparatus of the present embodiment and Examples 1 to 4 has a queue for storing cells in the order of arrival from the head for each connection.
Input means for storing the arriving cell in a queue corresponding to the connection to which the cell belongs, and when the cell stored in the queue reaches the head of the queue, the scheduling means determines the transmittable time of the cell. When the cell transmission means detects a cell whose transmission time is earlier than the current time, the cell transmission means takes out the cell with the earliest transmission time from the head of the queue and transmits it to the line. When transmitting, the scheduling means updates the parameter value corresponding to the connection to which the cell belongs, so there is a delay between the time at which a cell belonging to a certain connection can be transmitted and the time at which the cell is actually transmitted. Even if time occurs, the cell value can be updated by updating the parameter value based on the time when the cell is actually transmitted. Time is actually considered the delay time between the time a cell is transmitted from, it is possible to solve the clamping problems.

At the same time, when the cell stored in the queue reaches the head of the queue, the scheduling means determines the transmittable time of the cell, and the cell transmitting means determines that the transmittable time is before the current time. Is detected, the cell with the earliest possible transmission time is taken out from the head of the queue and transmitted to the line, and when the cell transmitting unit transmits the cell to the line, the scheduling unit corresponds to the connection to which the cell belongs. To update the parameter value
When a cell is stored in the queue, it does not determine the time at which the cell is actually transmitted, so the cell transmitting means can transmit the cells in the transmittable time order, and the cells caused by the cells not being sorted in the transmittable order. Can be suppressed from being reversed.

[0166] Further, a characteristic inherent to the ring buffer method, that is, a time at which a cell is actually transmitted when the cell is stored in the cell transmitting means, is not used, and a method such as a calendar method or a sequencer method is used. When storing cells, it is possible to use a cell transmitting means having a property that the time at which the cells are actually transmitted is not determined as realizing means.

As described above, the invention made by the present inventor
Although specifically described based on the embodiment, the present invention
It is not limited to the embodiment and each example,
Of course, various changes can be made without departing from the scope of the invention.

[0168]

The effects obtained by the invention disclosed in the present application will be briefly described as follows.

When the cell transmitting means transmits the cell to the line, the scheduling means updates the parameter value corresponding to the connection to which the cell belongs. Even if a delay time occurs between the time when the cell is transmitted, updating the parameter value based on the time when the cell is actually transmitted allows the cell to be actually transmitted from the time when the cell can be transmitted. The delay time between transmission times is taken into account, and the problem of clamping can be solved.

Further, when the cell transmitting means transmits the cell to the line, the scheduling means updates the parameter value corresponding to the connection to which the cell belongs. Is not determined, the cell transmitting means can transmit the cells in the order in which the cells can be transmitted, and can suppress the inversion of the transmission order of the cells caused by the cells not being sorted in the order in which the cells can be transmitted. .

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration of a cell shaping device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of a scheduling unit of the embodiment.

FIG. 3 is a flowchart showing an operation of a scheduling unit of the embodiment.

FIG. 4 is a diagram illustrating a configuration of a cell transmission unit according to the present embodiment.

FIG. 5 is a diagram illustrating a configuration of a second cell transmission unit according to the present embodiment.

FIG. 6 is a flowchart illustrating an operation of a scheduling unit according to the first embodiment.

FIG. 7 is a flowchart illustrating an operation of a scheduling unit according to the first embodiment.

FIG. 8 is a flowchart illustrating an operation of a scheduling unit according to the second embodiment.

FIG. 9 is a flowchart illustrating an operation of a scheduling unit according to the second embodiment.

FIG. 10 is a flowchart illustrating an operation of a scheduling unit according to the third embodiment.

FIG. 11 is a flowchart illustrating an operation of a scheduling unit according to the third embodiment.

FIG. 12 is a flowchart illustrating an operation of a scheduling unit according to the fourth embodiment.

FIG. 13 is a flowchart illustrating an operation of a scheduling unit according to the fourth embodiment.

FIG. 14 is a diagram for explaining a configuration of a shaper according to a conventional token system.

FIG. 15 is a diagram illustrating a configuration of a shaper according to a conventional GCRA method.

FIG. 16 is a flowchart showing the operation of the conventional shaper scheduling means of the GCRA method.

FIG. 17 is a diagram for explaining a cell transmission unit using a ring buffer system.

FIG. 18 is a diagram for explaining a cell transmission unit using a calendar method.

FIG. 19 is a diagram for explaining a cell transmission unit using a sequencer method.

FIG. 20 is a flowchart showing the operation of a scheduling means for solving the shaper clamping problem according to the conventional GCRA method.

[Description of Signs] 101: input means, 102, 103 ... queue, 104,
105: transmission timing generation means, 106: arbitration means,
201: storage means for storing traffic characteristic values and parameter values, 202: clock means, 203: scheduling means, 204: cell transmission means, 801: storage section for storing traffic characteristic values and parameter values, 802: clock section,
803: scheduling unit, 804: cell transmission unit, 8
05, 806: queue, 807: input unit.

Claims (5)

[Claims] 1. A storage unit for storing traffic characteristic values and parameter values for each connection, a clock unit for counting a current time, and a unit corresponding to a connection to which an arrived fixed-length packet (hereinafter, referred to as a cell) belongs. Scheduling means for determining the transmittable time of the cell based on the traffic characteristic value, the parameter value, and the current time counted by the clock means, updating the parameter value, and determining the transmittable time by the scheduling means. A cell shaping device including a cell transmission unit for detecting a cell in which the transmittable time is before the current time based on the current time counted by the clock unit, and transmitting the cell to a line. A queue provided for each connection and storing cells in the order of arrival from the top; Input means for storing a cell in a queue corresponding to a connection to which the cell belongs, wherein the scheduling means can transmit the cell when the cell stored in the queue reaches the head of the queue. Means for calculating and determining time, and when the cell transmitting means transmits a cell to a line, the cell transmitting means has a means for updating a parameter value corresponding to a connection to which the cell belongs, the cell transmitting means, Detecting a cell whose transmission possible time determined by the scheduling means is before the current time,
A cell shaping device comprising means for taking out the cell with the earliest possible transmission time from the head of the queue and transmitting it to the line. 2. The cell shaping device according to claim 1, wherein a current time when calculating a transmittable time of a cell is ta, a current time when updating a parameter value is te, and a connection to which the cell belongs. The value of the cell interval of the traffic characteristic value corresponding to T, the value of the allowable fluctuation of the cell delay time is τ, the parameter value corresponding to the connection to which the cell belongs is TAT, and the transmittable time of the cell is ts. Then, the scheduling means determines that the cell can be transmitted ts
When calculating the following equation, when the relation of ta <TAT−τ is established, the transmittable time ts of the cell is set to TAT−τ. When the relation of TAT−τ ≦ ta is established, the transmittable time of the cell ts is set. Is determined as ta, and the parameter value TAT is determined.
When updating the parameter, the parameter value TAT is updated to TAT + T when the relation of te <TAT is satisfied, and the parameter value TAT is updated to te + T when the relation of TAT ≦ te is satisfied. A cell shaping device characterized by the above-mentioned. 3. The cell shaping device according to claim 1, wherein a current time when calculating a transmittable time of a cell is ta, a current time when updating a parameter value is te, and a connection to which the cell belongs. The value of the cell interval of the traffic characteristic value corresponding to T, the value of the allowable fluctuation of the cell delay time is τ, the parameter value corresponding to the connection to which the cell belongs is TAT, and the transmittable time of the cell is ts. Then, the scheduling means determines that the cell can be transmitted ts
When calculating the following equation, when the relation of ta ≦ TAT−τ is established, the transmittable time ts of the cell is set to TAT−τ. When the relation of TAT−τ <ta is established, the transmittable time ts of the cell is set. Is determined as ta, and the parameter value TAT is determined.
When the relation of te ≦ TAT is satisfied, the parameter value TAT is updated to TAT + T, and when the relation of TAT <te is satisfied, the parameter value TAT is updated to te + T. A cell shaping device characterized by the above-mentioned. 4. The cell shaping device according to claim 1, wherein the current time when calculating the transmittable time of the cell is ta, the current time when updating the parameter value is te, and the connection to which the cell belongs. , The parameter value corresponding to the connection to which the cell belongs is TET, and the transmittable time of the cell is ts. Then, the scheduling means determines that the cell can be transmitted ts
When calculating the following equation, when the relation of ta <TET is established, the transmittable time ts of the cell is set as TET, and when the relation of TET ≦ ta is established, the transmittable time ts of the cell is determined as ta; When the parameter value TET is updated, the parameter value TET is updated to TET + T when the relationship of te <TET + τ holds, and the parameter value TET is changed to te−τ + T when the relationship of TET + τ ≦ te holds. A cell shaping device having means for updating. 5. The cell shaping device according to claim 1, wherein a current time when calculating a transmittable time of a cell is ta, a current time when updating a parameter value is te, and a connection to which the cell belongs. , The parameter value corresponding to the connection to which the cell belongs is TET, and the transmittable time of the cell is ts. Then, the scheduling means determines that the cell can be transmitted ts
When calculating the following equation, when the relation of ta ≦ TET is established, the transmittable time ts of the cell is set as TET, and when the relation of TET <ta is established, the transmittable time ts of the cell is determined as ta; When updating the parameter value TET, if the relationship of te ≦ TET + τ is established, the parameter value TET is updated to TET + T. If the relationship of TET + τ <te is established, the parameter value TET is changed to te−τ + T. A cell shaping device having means for updating.