JP3201551B2 - Shaping circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaping circuit for correcting a cell flow having a fluctuation in cell intervals in ATM communication to a cell flow having a small fluctuation.

[0002]

2. Description of the Related Art In a cell flow transmitted by ATM communication, the intervals between cells vary due to various factors. That is, the cell flow has a cell delay variation (CV
D: CellDelay Variation). When such a cell flow having a fluctuation in cell interval is transferred into the ATM network, the cell coverage in the ATM network is reduced. Therefore, a shaping circuit for keeping the cell interval constant is used.

FIG. 7 is a block diagram showing a configuration example of a conventional shaping circuit. This shaping circuit includes a cell separation circuit 31 for separating cells of an input cell flow from the signal line 103 in connection with a connection, and temporarily stores cells corresponding to each connection, and conditions for each connection (notified on the signal line 102). Cycle output circuits 33a to 33n that periodically output in principle according to a peak cell speed, etc.)
And a cell multiplexing circuit 32 that multiplexes the outputs of the periodic output circuits 33a to 33n and outputs the multiplexed output to the signal line 108.

That is, the shaping circuit operates by manipulating the phase of each cell in the cell stream so that CVD approaches zero. For example, as shown in FIG. 8A, when one cell flow having a fluctuation in the cell interval is input to the shaping circuit, the output becomes as shown in FIG. 8B.
The cell flow has no fluctuation. Therefore, if the cell flow that has passed through the shaping circuit is transferred to the ATM network, the cell capacity in the ATM network is improved.

[0005] The conventional shaping circuit performs a shaping process on an incoming cell stream for all connections. The maximum number of connections is 256 for virtual path connections and 4096 for virtual channel connections.

[0006]

Therefore, the conventional shaping circuit performs the shaping process up to the maximum number of connections that can be set, so that there is a problem that the scale of hardware such as a memory becomes extremely large.

The present invention has been made to solve such a problem, and distinguishes between those that need to perform shaping processing and those that do not, and performs shaping processing only on those that need to be processed. It is an object to provide a shaping circuit.

[0008]

According to a first aspect of the present invention, a shaping circuit compares a report parameter of a user with a determination condition defined on a network side, and performs a shaping process on a connection related to the report parameter. A determination circuit for determining whether or not to perform the processing; a processing target cell separation circuit for separating a shaping processing target from each cell of the input cell stream according to a determination result of the determination circuit; and a shaping process separated by the processing target cell separation circuit And a shaping unit that performs a shaping process on a target cell.

[0009] Further , the present invention provides the shaping circuit of the first aspect.
The judgment circuit responds to each peak cell speed as a judgment condition.
The maximum cell delay variation value is used.

[0010] The shaping circuit according to the second aspect of the present invention.
The route is defined by the user's declaration parameters and the network side
Compare with the judgment condition, and
Whether to perform shaping processing on the connection
According to the determination circuit to determine, and the determination result of this determination circuit,
From each cell in the input cell flow,
The target cell separation circuit to be separated and the target cell
For the shaping processing target cells separated by the separation circuit
And a shaping unit for executing a shaping process.
Things. Also provided for the shaping circuit of claim 2.
The judgment circuit determines the peak cell speed as a judgment condition.
Threshold for all thresholds and maximum cell delay variation
Use a different value.

[0011] The shaping circuit according to the third aspect of the present invention.
The road is a shape pipe according to the first or second aspect of the invention.
In a switching circuit, a determination circuit is provided from outside the determination circuit.
Is configured to set the judgment condition according to the instruction of
Things.

[0012] A shaping circuit according to a fourth aspect of the present invention.
The road is a shape pipe according to the first or second aspect of the invention.
In the networking circuit, the judgment circuit is
After that, the judgment condition is changed.
You.

[0013]

When a connection setting condition is compared with a network condition, there is a connection for which the cell flow does not need to be subjected to a shaping process. For example, for a connection for which the effect of reducing the connection capacity due to the shaping process cannot be expected, the shaping process is not so effective. The shaping circuit according to the present invention utilizes this fact to determine whether or not the connection requires shaping processing based on the user's report parameter, and performs shaping processing only on the necessity.

[0014]

FIG. 1 is a block diagram showing a configuration of a shaping circuit according to a first embodiment of the present invention. This shaping circuit includes a judgment circuit 1 for judging whether or not to perform a shaping process for each connection based on a judgment condition inputted through a signal line 101; , A shaping unit 3 that performs shaping processing, and each output cell of the shaping unit 3 and a cell that has not been subjected to shaping processing from the processing target cell separation circuit 2 are multiplexed into a signal. And a multiplexing circuit 4 for outputting to the line 108. The configuration of the shaping unit 3 is the same as the configuration of the conventional shaping circuit.

As shown in FIG. 2, the connection capacity required to accommodate a cell stream having a CDV tends to increase as the CDV increases. Also, CDV
If the values are the same, the higher the peak cell rate, the greater the required connection capacity. Therefore, it can be seen that when a shaping process is performed on a cell flow having a large CDV or a cell flow having a high peak cell speed, the effect of reducing the connection capacity appears remarkably.

In FIG. 2, V1, V2, and V3 indicate peak cell speeds, and the scale on the vertical axis is based on the connection capacity when CDV = 0, and becomes larger as it goes down. I have. A straight line A indicates a value corresponding to an allowable increase in the connection capacity.

FIG. 3 shows this relationship, where the horizontal axis represents the peak cell velocity and the vertical axis represents the CDV value. In FIG. 3, the curve A corresponds to the straight line A in FIG. Then, the upper range of the curve A is set as the range in which the shaping process is performed. That is, if there is an allowable increase in the connection capacity, the shaping process is not performed.

Next, the operation of the shaping circuit shown in FIG. 1 will be described. The shaping circuit is installed at an appropriate place in the ATM network. The determination circuit 1 is given a determination condition shown by a curve A in FIG. Judgment circuit 1
Holds the determination condition. Specifically, the determination circuit 1
For example, each CDV value corresponding to each peak cell speed may be stored in a table format as a determination condition (threshold). The determination condition setting for the determination circuit 1 may be performed only once at the start of the operation, or may be performed each time the determination condition changes due to a change in the network operation status. In addition, the timing of the determination condition setting can be set when a user's connection setting request is made or at any time.

In order to perform ATM communication, the user notifies the network of specified connection setting conditions (report parameters) and requests connection setting. When the network accepts the connection setting, the connection setting condition is notified to the determination circuit 1 via the signal line 102. The connection setting conditions include a maximum CDV value and a peak cell speed.

The judgment circuit 1 compares the notified connection setting condition with the held judgment condition, and judges whether or not to perform a shaping process on the connection. Then, the determination result is notified to the processing target cell separation circuit 2 via the signal line 103. The processing target cell separation circuit 2
The judgment result of the judgment circuit 1 is held. Then, the cells of the input cell flow are separated according to the held determination result, and the cells of the connection that are not subjected to the shaping process are connected to the signal line 1.
Output to 05. Further, the cell of the connection for which the shaping process is performed is output to the signal line 106.

Each connection setting condition (at least the peak cell speed) required in the shaping process is given to the shaping unit 3 via the signal line 109. The shaping unit 3 has, for example, the configuration shown in FIG. 1. In the shaping unit 3, first, each cell input from the signal line 106 is separated by the cell separation circuit 31 corresponding to the connection. The separated cells are input to the corresponding periodic output circuits 33a to 33n. Each cycle output circuit 33a-3
3n temporarily stores the input cells, and periodically reads out the stored cells using the peak cell speed or the like given on the signal line 109 and outputs the read cells to the cell multiplexing circuit 32. The cells output from each of the periodic output circuits 33a to 33n are multiplexed by the cell multiplexing circuit 32, and
07.

The cell multiplexing circuit 4 multiplexes the cell transferred on the signal line 107 and the cell which has not been subjected to the shaping process transferred on the signal line 105, and uses the multiplexed cell as an output cell stream. Output to line 108. In addition,
As a multiplexing method in the cell multiplexing circuit 4, a method of outputting in FIFO order in the order of input time or a method of
There is a method of polling 5,107 alternately.

FIG. 4 is an explanatory diagram showing another example of the judgment condition held in the judgment circuit 1. Straight lines A and B in FIG. 4 are determination conditions. That is, 1 for peak cell rate
One threshold is set and one threshold is set for the CDV value. This determination condition is a simplification of the determination condition shown in FIG. 3, and has an advantage that the determination circuit 1 does not require a memory for a table, although the strictness of the determination is lacking.

FIG. 5 is a block diagram showing a configuration of a shaping circuit according to a second embodiment of the present invention. In this case, a priority multiplexing circuit 5 is provided instead of the cell multiplexing circuit 4 shown in FIG. The priority multiplexing circuit 5 inputs the cells output from the shaping unit 3 in preference to the cells that have not been subjected to the shaping processing from the processing target cell separation circuit 2. Therefore, the cells output from the shaping unit 3 are not subjected to the cell delay fluctuation in the priority multiplexing circuit 5. However, since the cells from the processing target cell separation circuit 2 are frequently kept waiting, the CDV becomes somewhat large. Therefore, this embodiment is effective when it is not desired to increase the CDV of a cell of a connection having a high peak cell rate.

FIG. 6 is a block diagram showing a configuration of a shaping circuit according to a third embodiment of the present invention. In this shaping circuit, the determination circuit 1 operates in the same manner as in the first embodiment, and determines whether or not to perform a shaping process for each connection.

The cell separation circuit 6 separates each cell of the input cell stream into cells to be subjected to shaping processing and cells not to be subjected to shaping processing, and separates cells to be subjected to shaping processing into each connection based on the judgment result of the judgment circuit 1. Perform the following processing. Each of the periodic output circuits 33a to 33n operates in the same manner as in the first embodiment, temporarily stores cells corresponding to each connection, and then periodically outputs the cells according to the conditions of each connection notified by the signal line 109. . The cell multiplexing circuit 7 multiplexes the outputs of the periodic output circuits 33a to 33n and the cells not subjected to the shaping processing from the cell separation circuit 6, and outputs the result to the signal line 108.

Comparing the configuration of this shaping circuit with the configuration of the shaping circuit according to the first embodiment, the point that the cell separation circuit 2 to be processed and the cell separation circuit 31 in the first embodiment are integrated into one. And that the cell multiplexing circuit 32 and the cell multiplexing circuit 4 are integrated into one. In addition, C of a cell that is not subjected to shaping processing
The DV increases by about the number of connections subjected to the shaping process, and becomes a value substantially intermediate between the case of the first embodiment and the case of the third embodiment.

[0028]

As described above, claims 1 and 2
According to the invention described in Item 2 , the shaping circuit compares the report parameter of the user with the determination condition defined on the network side, determines whether or not to perform the shaping process on the connection related to the report parameter, and performs the shaping process. Since the configuration is such that the shaping process is executed for the target object, the shaping process can be executed only for the objects that have a large effect of reducing the connection capacity by the shaping process, etc. There is an effect that a product that can achieve effective shaping can be provided.

According to the first aspect of the present invention, the shell
The ipping circuit responds to each peak cell speed as a judgment condition.
Is configured to use the maximum cell delay variation
The effect of the connection capacity reduction by the shaping process
Performs shaping processing only on objects with large results.
It has the effect of providing what you do.

According to the second aspect of the present invention, the shell
The ipping circuit determines the peak cell speed as a judgment condition.
Threshold for all thresholds and maximum cell delay variation
And the value of the judgment circuit.
Simplifies the configuration and further reduces the amount of hardware
There is an effect that can be provided.

According to the third aspect of the invention, the shape pin
The judgment circuit according to an instruction from outside the judgment circuit.
Configuration, so it is flexible according to network conditions.
There is an effect that a soft thing can be provided.

According to the fourth aspect of the present invention, the shape pin
Circuit changes judgment conditions after network operation status changes
It has a more detailed shape
There is an effect that it is possible to provide a device that can perform the switching process.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a shaping circuit according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a connection capacity, a peak cell rate, and a maximum CDV value.

FIG. 3 is an explanatory diagram illustrating an example of a determination condition.

FIG. 4 is an explanatory diagram showing another example of a determination condition.

FIG. 5 is a block diagram showing a configuration of a shaping circuit according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a shaping circuit according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a conventional shaping circuit.

FIG. 8 is a timing chart showing an operation of a conventional shaping circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Judgment circuit 2 Processing cell separation circuit 3 Shaping part 4 Cell multiplexing circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (4)

(57) [Claims] 1. A shaping circuit that corrects and outputs a cell delay variation of an input cell flow, and compares a user's declared parameter with a determination condition defined as a maximum cell delay variation value corresponding to each peak cell speed. A determination circuit for determining whether or not to perform a shaping process on the connection relating to the report parameter; and a processing target cell separation circuit for separating a shaping target from each cell of the input cell flow according to a determination result of the determination circuit. A shaping circuit comprising: a shaping unit that performs a shaping process on a shaping process target cell separated by the process target cell separation circuit. 2. A shaping circuit for correcting and outputting a cell delay variation of an input cell flow, wherein the shaping circuit is defined by a threshold value for a user declared parameter, a threshold value for a peak cell speed, and a threshold value for a maximum cell delay variation value. A determination circuit that determines whether or not to perform a shaping process on the connection relating to the report parameter by comparing the determination condition with the determination condition; and a process of separating a shaping process target from each cell of the input cell flow according to the determination result of the determination circuit. A shaping circuit, comprising: a target cell separation circuit; and a shaping unit that performs a shaping process on a cell to be subjected to shaping processing separated by the processing target cell separation circuit. Wherein determining circuit according to claim 1 or claim 2 shaping circuit according setting a determination condition in accordance with an instruction from the outside of the judging circuit. 4. The method according to claim 1, further comprising the step of: determining whether or not the operation status of the network changes.
In claim 1 or claim 2 shaping circuit according to change the determination condition.