JPH03190341A - Traffic control system in atm exchange - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding a traffic control method for an ATM switch that discards cells that cannot fit into the buffer, the present invention discards cells that continue to flow in before entering the communication path within the switch. In order to improve the efficiency of the call path by setting a flag in the cell discard field column of the VCI conversion table to avoid discarding cells that are strict about discarding data, etc., calls that are not strictly discarded are flagged and discarded. discards only calls with flags set. When the quality of service deteriorates due to continuous discards, calls are intermittently discarded according to the value generated by the random number generator. For the purpose of the above three processes, input information is converted into cells, which are short fixed length information, and statistically multiplexed.
In a TM switch, when an ear is received, a discard flag setting means sets a flag to a cell that is not strict to discard, and a discard flag storage means stores a flag indicating that the cell set by the discard flag setting means can be discarded. and overflow detection means for detecting whether the capacity of cells temporarily stored in a buffer in a routing communication path in an ATM switch exceeds a predetermined capacity; cell discarding means for discarding cells that may overflow the buffer and can be discarded based on overflow information of the buffer and flag information indicating that cells can be discarded and stored in the discard flag storage means; and a random number generating means for generating random numbers in order to randomize the interval of cell discard by the cell discarding means, and outputting information indicating a discard execution period and a discard execution impossible period to the cell discard means based on the random number. It is configured to have the following.

[Industrial application field]

The present invention relates to a traffic control method for an ATM switch,
More specifically, the present invention relates to a traffic control system for an ATM switch that discards cells that cannot fit into a buffer.

[Conventional technology]

Broadband+A is a next-generation communication network that integrates all kinds of information communication services such as voice, data, and video images.
Research and development of l5DN is currently being actively conducted.

Among them, ATM (Asynchronous T
transfer mode (asynchronous transfer mode) is a fixed transfer mode that handles continuous information such as audio and moving images, burst information such as CAD and CAM data, and a fixed type of information called cells, regardless of the communication speed of each piece of information. This is a technology that converts information into information and then transfers it at high speed. The ATM switch to realize this technology is currently under development and is expected to be commercialized around 1993.

Traffic control is necessary to realize the various services provided by ATMs. To achieve this, the user first declares the call traffic characteristics and required communication quality when accepting a call, and the communication network determines whether or not these declarations can be satisfied. It is conceivable to realize priority control in which transfer processing is performed with priority according to the required quality. For example, if priority control is implemented, cells for video communication that require real-time performance can be transferred faster with priority over cells for other data.

However, if the call acceptance control logic is not appropriate, if the user inputs cells in excess of the declared capacity, or if burst-like large-capacity information overlaps, the capacity of the input cells may exceed the call path. A problem arises in that the capacity of the device is exceeded. In order to avoid exceeding the capacity of the communication path, it is necessary to store excess cells, that is, the buffer memory provided in the communication path of the exchange for temporarily storing input cells. It is necessary to discard the cells that have been used.

However, in the past, cells that could no longer fit into the buffer in the communication path of the exchange were naturally discarded.

In other words, all cells that cannot fit into the buffer are discarded regardless of the type of service.

FIG. 6 is a block diagram of a conventional ATM switch.

The ATM switch includes a call control section 60, a plurality of vCI (logical channel identifier) conversion sections 61, a self-routing channel 62, and a traffic control section 63.

The call control unit 60 accepts calls from users and sets up calls.

On the other hand, the VCI converter 61 includes a VCI converter 64, and each VCI converter 61 processes information of one call. First, the VCI converter 64 converts VCI from the input highway 66 to VCI converter 64 .
Output information 69 and routing information 70 which are outputted from the output highway 68 of the ATM switch are generated from the cell 67 inputted to the CI conversion unit 61 . The VCI conversion device 64 has a VC4 conversion table 71 for converting the input cell 67 into routing information for connecting it to the output highway.
have.

Self-routing path 62 is a hardware switching scheme that requires no software processing. Multi-stage S
RM72 (self-routing memory: self-
routing memory,,S RM-1,S
RMIL SRM-Ill), each SRM
72 has n inputs, n outputs, and n buffers y 73 (the n buffers of SRM-1 (72-I) are 73(+, 73 Iz, . . . 73-It.

..., 73-In). Then, the VCI converter 61
S of each stage according to the routing information 70 input from
Routing RM. And the final stage SRM (
In this case, SRM-III) outputs the routed cell on output highway 6.

Here, the flow of the ATM exchange operation will be explained with reference to FIG.

First, the user inputs a call acceptance request 74 to the call control unit 60. The call control unit 60 sets which route the call information is to be output to the output highway 68, and creates a corresponding tag. Write the set tag and new vCI to the C1 conversion table in the VC conversion unit. Traffic flowing between the first stage (SRM-1) and the last stage (SRM-111) is allocated so that the traffic on each link is equal. After completing the call setting, the call control unit 60 notifies the traffic control unit 63 that the call will be input.

On the other hand, the cells 67 in which the routing address a is written by the call setting of the call control section 60 are input to the VCI conversion section 61 one after another from the human-powered highway 66 .

The cell 67 is first input to the VCI conversion device 64. Then, the CI conversion device 64 extracts the routing route 75 (kj-i) and the outgoing route information 76 by looking up the address a (address information for routing written by the call control unit 60) in the VCI conversion table 71. get. The routing information 75 (k-j-i) is the i-th SRM-1 in the first-stage SRM-1, the second SRM-II in the second-stage SRM-II, and the second-stage SRM
III means passing through the jth route.

The VCI conversion device 64 generates output information 69 and routing information 70 from the routing information 75 and outgoing route information 76 obtained by looking up the VCI conversion table 71, and outputs them to the self-routing channel 62. Output information 6
9 includes actual information and exit route information 76.

Output information 69 input to self-routing channel 62
The routing information 70 reads out the routing information of the first stage SRM-1 written in the routing information 70. In this case, it is i, so the i-th buffer 7
Output information 69 is stored in 3-11. The buffer 73 is FIFO (first-in first-ou).
t), and outputs the output information 69 stored first to the next SRM in order.

The output information 69 stored in the buffer 13 (+) of the first stage SRM-I is then sent to the second stage SRM-I together with the routing information (k-j) from which the first stage routing information i has been deleted.
Input to RM-II. Since the routing information of the second stage SRM-II is j, the output information 69 is temporarily stored in the j-th buffer 73-LL. When the state is ready for output, the output information 69 is sent to the third stage SRM-Ill together with the routing information (k) obtained by deleting the second stage routing information, and is sent to the kth buffer 73-II.
l, temporarily stored. When it is ready to output,
Output information 69 is output from output highway 6th.

The ATM exchange operates as described above.

Problem to be solved by the invention] However, in the conventional system, when the capacity of the buffer in the self-routing channel is exceeded, cells that are newly generated cannot be suppressed, and cells continue to flow into the exchange. This causes three types of problems: a significant drop in throughput, a possibility that cells with strict data discard rates may be discarded, and a possibility that cells may be discarded successively. For example, if the discarded information is data, the discarded portion of the data will be lost. Since replay is impossible, the entire data becomes meaningless and it becomes necessary to retry the communication.

On the other hand, if the information to be discarded is video or audio, if the amount of discarded information is small, the S/N (signal-to-noise ratio) will drop, but the meaning will remain, and there will be no need to communicate again. do not have.

The present invention aims to improve the efficiency of the communication path by discarding cells that continue to flow in before they enter the communication path in the exchange, and avoids discarding cells that are difficult to discard, such as data. A flag is set for calls that are not subject to discard in the cell discard field provided on the VCI translation table.
When discarding calls, only calls with flags set are discarded. When the quality of service deteriorates due to continuous discards, calls are intermittently discarded according to the value generated by the random number generator. The purpose is the above three processes.

[Means to solve the problem]

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

First, it has a discard flag setting means 2 and a discard flag storage means 3. The discard flag setting means 2 determines whether or not the call is subject to discard based on the ear reception information 9 input by the user to the ATM switch 1 when requesting call setup, and if the call is not subject to discard. A flag indicating that the call can be discarded is set in the cell information of the call. On the other hand, the discard flag storage means 3 stores a flag set by the discard flag setting means 2 indicating that discard is possible for each cell.

On the other hand, overflow detection means 6 detects that cells are stored in buffer 5 in routing channel 4 of ATM exchange 1 in excess of a predetermined threshold. If detected, overflow information to that effect is notified to the cell discarding means 7.

The cell discarding means 7 receives overflow information from the overflow detecting means 6 and executes cell discarding processing. When discarding a cell, it is determined whether or not the discardable flag of each cell stored in the discard flag storage means 3 is set, and only cells with the discardable flag set are regarded as discardable cells. Furthermore, by referring to the discard execution period/discard execution impossible period information from the random number generation means 8, which will be described later, the cell is determined to be a cell only if the cell input to the cell discard means 7 is a discardable cell and is in the discard execution period. discard.

On the other hand, if the cell input to the cell discarding means 7 is not a cell that can be discarded, or if the information input from the random number generating means 8 is a period in which discarding is not possible, the cell is not discarded.

The aforementioned random number generating means 8 generates a random number, determines a discard execution period and a discard execution impossible period based on the value of the random number, and informs the cell discard means 7 whether it is the discard execution period or the discard execution impossible period. Uke will pass on the information.

[For production]

If the user wishes to transfer information, the user first inputs call acceptance information 9 to ATM switch 1 to set up a call. The call acceptance information 9 includes traffic information indicating the type of information to be transferred, that is, voice, image, or data, and whether or not it is large-capacity information such as moving images or burst information. .

The discard flag setting means 2 takes this call acceptance information 9 as input and determines based on the call acceptance information 9 whether the call information is information that can be discarded to some extent or information that cannot be discarded. , if it can be discarded, sends a signal to the discard flag storage means 3 to set a flag indicating that it is discardable.

On the other hand, call acceptance information 9 is input to the ATM switch 1,
Once the call is accepted, the actual information (cell) is
It is input to the TM exchange 1. The cell 10 is first input to the discard flag storage means 3.

The discard flag storage means 3 has secured a discardable flag storage area for the cell 10, and if a signal for setting the discardable flag is input from the discard flag setting means 2, the flag is set.

If the signal that sets the discardable flag is not input, the discardable flag for that cell is not set.

The discard flag storage means 3 outputs information on cells and discardable flags to the cell discard means 7.

The cell discarding means 7 receives and receives information on cells and discardable flags from the discarding flag storage means 3. At this point, the overflow information of the buffer 5 in the routing channel 4 inputted from the overflow detection means 6 is on.
Moreover, if the information on the discard possible/impossible period inputted from the random number generating means 8 is the discard possible period, that cell is discarded. On the other hand, if the overflow information from the overflow detection means 6 is OFF, or the information on the discard possible/impossible period from the random number generation means 8 is the discard impossible period, the cell discard means 7 discards the cell. Instead, it is passed to the routing channel 4 and temporarily stored in the buffer 5. The cells stored in the buffer 5 are sequentially A
The data is sent from the TM exchange 1 to the outside.

When cells are stored in the buffer 5, the capacity of the cells stored in the buffer 5 increases. At this time, if the storage capacity of the buffer 5 exceeds a preset threshold, a signal indicating that the threshold has been exceeded is output to the overflow detection means 6. When the overflow detecting means 6 receives this signal, it determines that the buffer 5 is almost full and turns on the overflow information to the cell discarding means 7. Otherwise, overflow information is turned off.

On the other hand, the random number generating means 8 generates a random number, and uses this value as an interval for discarding cells. That is, for example, 1
If a random number between ~10 is generated and a value of 5 is obtained, information that makes discarding impossible only during the period when 5 cells are input to the cell discarding means 7 and sent out to the routing channel 4. That is, the cell discarding unit 7 outputs discarding impossible period information to the cell discarding means 7. Thereafter, information that enables the discard execution, that is, discard executable period information, is sent to the cell discard means 7, thereby making it possible to execute the discard process for one cell. Furthermore, next, the cell discarding unit 7 sends discarding impracticable period information to the cell discarding means 7 only during the next random number. By doing this, the intervals at which cells are discarded become random.

As described above, cells that can be safely discarded based on the type of call information are flagged, and when buffer 4 is likely to overflow, the flagged cells are discarded at random intervals before entering the switch. Discard.

[Example] Hereinafter, an example will be described with reference to FIGS. 22 to 5.

FIG. 2 is a system configuration diagram of an embodiment of the present invention.

The ATM switch is composed of a call control section 20, a plurality of CI (logical channel identifier) conversion sections 21, a self-routing channel 22, and a traffic control section 23. The present invention relates to the call control section 20 and the CI conversion section 21.

First, the overall configuration will be explained.

The call control unit 20 accepts calls from users and sets up calls.

On the other hand, the vCI conversion unit 21 generates control information such as information for outputting the call cell set by the call control unit from the ATM switch, routing information, and discardable flag information, and also generates control information such as self-routing flag information. It outputs to line 22.

At this time, if the amount of information in the self-routing channel 22 becomes excessive, discardable cells are discarded. The VCI conversion unit 21 includes a VCI conversion device 24 and a cell discard device 2.
5. Consists of a random number generator 38.

First, the VCI conversion device 24 has a VCI conversion table 31, sets the control information of the cell 27 inputted from the input highway 26 to the VCI conversion unit 21 by referring to the C conversion table 31, and sets the control information of the cell 27 by referring to the ■C■ conversion table 31. , AT
Output information 29 output to the output highway 28 of the M exchange
and generates control information 30. Output information 29 includes actual call information (e.g., voice, image, data information) and outgoing route information 36, while control information 30 includes routing information (tags 35) and VCI conversion table 31 information. Contains discardable flag information stored in the cell discard field 39.

Next, the cell discard device 25 discards the control information 30 when it is necessary to discard the cell according to a signal from the traffic control unit 23.
With reference to the discardable flag information included in the discard flag information and the information from the random number generator 38, if the discardable flag is set and the information from the random number generator 38 indicates that the discard process can be executed, Cell 27, ie, output information 29 and control information 30, are discarded. If not disposed of,
The receiver passes output information 29 and control information 30 to self-routing channel 22 .

Here, the random number generator 38 sets the interval at which cells are discarded. The random number generator 38 generates a random number, makes it impossible to discard a cell within the period of the number of cells of that value, and allows discarding one cell after the period ends,
Furthermore, the cell discard interval is determined such that the number of cells corresponding to the next random value cannot be discarded, and then only one cell can be discarded. Then, the cell discarding device 25 receives a signal indicating either a period in which discarding is possible or a period in which discarding is not possible.

Self-routing channel 22 is a hardware switching system that requires no software processing. The self-routing communication path 22 has multiple stages of SRM 32 (self-routing memory: self-routing memory).
ry, three-stage SRM in the same figure, that is, SRM-
I%SRM-II, SRM-III). Each SRM32 has n inputs and n outputs,
and n buffers y 33 (SRM-1(32-I
) are 33-L, 33-Izl, 33
-I, 1. ,． 33-I,). The buffer 33 is a memory area that temporarily stores the output information 29, and can be configured by, for example, a FIFO (first-in, first-out) memory. That is, information is sent to the next stage SRM in order from the output information of the cell stored first.

In the self-routing channel 22, the routing information of the control information 30 input from the VCI converter 21 (-j-i in the figure indicates that the first stage routing information is i, the second stage is j, and the third stage is is k), the SRMs at each stage are routed. That is, if the routing information for the first stage SRM-I is i, the output information 29 is temporarily stored in the i-th buffer 331t, and then when routing to the second stage SRM-11, the output information 29 is stored in the second stage SRM-1. Buffer 33-II according to the routing information j of
The output information 29 is temporarily stored in . And the third stage S
In the RM-111, the output information 29 is temporarily stored in the second buffer 33-111k based on the routing information. Thereafter, output information 29 from the second output highway 28 of the self-routing channel sends information outside the ATM switch.

Generally, a plurality of input highways 26 and the same number of VCI converters 21 as there are input highways 26 are connected to the self-routing channel 22 . Cells input from each input highway are then multiplexed within the self-routing channel 22. That is, the routing information (tag 35) is determined by the VCI conversion device 24 for each cell input from a plurality of input highways, and the information of each cell is routed through the self-routing channel 22 in accordance with that information.

On the other hand, the traffic control unit 23 has the role of controlling the traffic flowing into the self-routing channel 22. When the storage capacity of each buffer 33 in the self-routing channel 22 exceeds a predetermined threshold, a signal indicating that the storage capacity has exceeded the threshold is input to the traffic control unit 23. The traffic control unit 23 passes information indicating which buffer is about to become full to the cell discarding device 25.

Next, the operation of the ATM switch will be explained with reference to the same figure.

First, a user inputs a call acceptance request 34 to the call control unit 20. Based on the traffic characteristics of the call included in this acceptance request, the call control unit 20 sets which route the call information is to be output to the output highway 28. Information regarding the set routing is stored in the VCI conversion table 31 (7) in the VCI conversion device 24.
) Written to a7F reply. a is the VCI conversion device 24
This is the address of the VCI conversion table 31 that exists in the self-routing channel 22.
In addition to storing internal routing route information (tag 35) and outgoing route information 36, there is also a flag area indicating the possibility of discarding the cell, that is, a cell discard field 39.

After the call control unit 20 completes the call acceptance described in the conventional method as described above, the call control unit 20 determines whether the information of the call is such that there is little problem in discarding some cells. ,
In other words, whether the call information is information such as voice or image that makes sense even if some cells are missing, or whether it is information such as data that has no meaning if even a small part of the cell is discarded. Determine whether the information is likely to disappear. If the cell is discardable, a flag is set in the cell discard field 34 of the VCI conversion table 31 (for example, the flag bit is set to 1°).

On the other hand, if the cell cannot be discarded, the flag is not set (for example, the flag bit is set to 0°). When these processes of the call control unit 20 are completed, the call control unit 20 notifies the traffic control unit 23 that a call will be input, and activates the traffic control unit 23.

On the other hand, the VCI conversion unit 21 includes a VCI conversion table 31
The cells 27 in which the address a is written are input one after another from the input highway 26. First, the ■C■ conversion device 24 receives this cell 27, and by referring to the address a of the VCIi conversion table 31, output information 29 (output route information 36) outputs the cell 27 to the output highway 28.
) and the routing information of the tag 35 (k-j-i
) and the cell discardable flag information in the cell discard field 39 is generated, and the control information 30 is passed to the cell discard device 25.

The cell discard device 25 includes output information 29 and control information 30 from the VCI converter 24, and a traffic controller 23.
A cell discard request signal from the random number generator 38 and information indicating a discard executable period from the random number generator 38 are input. When the discard request signal is off, the cell discard device 25 does not discard the cell, but outputs the output information 2 input from the CI conversion device 24.
Routing information (tag 35) obtained by removing the disposable flag information from 9 and control information 30 is output to self-routing channel 22.

On the other hand, when the discard request signal is on, the cell discard flag included in the control information is set (for example, B), and the random number generator will only discard from 3 days when the signal indicates the discard executable period. Output information 29 and control information 30 of that cell
discard. If the cell discard flag is not set (for example, 0'') or if the signal from the random number generator 38 indicates a period in which discarding is not possible, the cell is not discarded and is output to the self-routing channel 22. Uke hands over information 29 and tag 35.

By doing so, it becomes possible to discard cells that can be discarded without much problem, and moreover, at random intervals.

FIG. 3 is a block diagram of a cell discard device in one embodiment.

The cell discarding device 25 is composed of a three-man-powered AND element 41 and a selector 42.

The AND element 41 receives the discard flag signal S1 in the control information 3o input from the VCI conversion device 24 to the cell discard device 25, the information S2 from the random number generation circuit 38, and the signal S3 from the traffic control section 23. is input. Then, all the signals of Sl, s2, and S3 are H (for example, “
1”), the output S4 of the AND element 41 becomes H(
For example, 1'). That is, the discard flag is set (Sl is "1"), and the signal from the random number generation circuit 38 is a signal indicating the period in which discard is possible (s2 is "1'", and s2 is the period in which discard is not possible). Si is set to 1 only when the signal from the traffic control unit 23 is a signal requesting discard (if 33 is '1' and there is no need to discard, S3 is set to "0"). Become ゛.

The output S4 of the AND element 41 becomes a select signal for the selector 42. That is, if Si is "1', selector 4
Cell information S5 input to 2 (output information 29 and tag 3
5) to the discard channel S6, which is one output channel of the selector 42, and if Si is °0', the cell information S
5 to output channel S7 to self-routing channel 22
Output to.

The circuit configuration as described above makes it possible to discard cells.

FIG. 4 is a configuration diagram of a traffic control section in one embodiment.

The traffic control unit 23 includes a matrix switch 43 and a matrix switch control unit 44. The matrix switch control unit 44 is connected to the call control unit 20, and the operation signal 310 of the traffic control unit 23 is transmitted from the call control unit 20 to the call control unit 20.
The receiver then operates the matrix switch 43. On the other hand, the matrix switch 43 includes each buffer, that is, the buffers 33-■, 33-11, 33- of each stage of the SRM.
Traffic information 37 (Sl 1-I
S311-II, SI l-111,...-)
tldiltc5, and the traffic information signal Sll of the buffer whose M product M amount exceeds a predetermined threshold becomes H (for example, 1'').

Also, the vertical line of the matrix (SI2-ISSI2-2
, . . , 512-n), among the n inputs of each SRM, only the line with the input number used for routing cell information from the cell discarding device 25 becomes H (for example, °l'). Both Sit and 312 turn on only the 1° matrix contact. This matrix contact corresponds to the discard switch, and when the discard switch is on, the cell discard device 25
The cell discard request signal S13 sent to is turned on.

In the case of the same figure, the matrix contacts that are turned on are 31
2-1, and the contact point of the line 312-3.312-4,
A signal is sent to the cell discard device to discard the cells with the 1st and 3.4th routing paths.

FIG. 5 is a configuration diagram of an ATM exchange in the case of three input highway channels and three output highway channels.

The ATM switch comprises a call control section 5o, three VC+ conversion sections 51-1.51-2.51-3, a self-routing channel 52, and a traffic control section 53.

3 channel input highway 54-1.54-2.54
-3 to each VCI converter 511.51-2.
Cell 55 is input to 51-3. Each VCI converter 51
A VCI conversion table 58 exists inside the VCI conversion table 58 including a tag 56 representing routing information and a cell discard field 57 storing a cell discardable flag. The address a written in the cell 55 by the call control unit 50 is the address of the VCI conversion table 58 in which the routing information and discardability flag of the cell 55 are stored.

The call control unit 50 receives a call acceptance request 59 from the user, and first determines which input highway 54 the cell 55 is to be input to. Then, a signal is sent to the traffic control unit 53 to activate traffic control. Further, an address of a VCI conversion table that optimizes the routing route is attached to the cell 55 depending on the type of call. Further, if the type of call is one for which there is no problem even if the cells are partially discarded, a flag is set in the cell discard field 57 at the position in the VCI conversion table indicated by the address a of the cell 55.

The VCI conversion unit 51 connected to each input highway 54 is connected to the call control unit 50, the traffic control unit 53, and the self-routing channel 52, respectively. Then, the call control unit 50 executes processing to set a flag in the cell discard field 57 in the VCT conversion table 58, and the traffic control unit 53 sends a message indicating that the storage capacity of the buffer in the self-routing channel 52 has exceeded a certain threshold. A signal informing the user of this, that is, a discard request signal is input. When this signal is input, the VCI converter 51 refers to the discard enable flag regarding the cell 55, and if the flag is set, the random number generator in the VCI converter 51 outputs a discard enable signal. Discard cells accordingly.

When the discard request signal is not input from the traffic control unit 53, when the discard possible flag is not set, or when the signal from the random number generator indicates that discard cannot be performed, the cell 55 is routed to the self-routing channel. 52.

Within the self-routing channel 52, routing processing is performed according to the routing information of each cell, and the cell is output from one of the output highways 59.

〔Effect of the invention〕

According to the present invention, when the buffer in a self-routing channel becomes full, it is possible to discard only cells that can be discarded without unconditionally discarding cells (instead of discarding cells unconditionally). This makes it possible to avoid discarding cells for information such as data that becomes meaningless if some of it is missing.

Furthermore, by controlling the cell discard interval using random numbers, cells with the same information are not continuously discarded. For example, regarding information encoded in the scanning line direction of an image, if cells are discarded consecutively, some scanning lines will be missing and the missing information will be noticeable, but according to the present invention,
Since cells are not discarded consecutively, it is possible to discard cells in such a way that missing cells are hardly noticeable.

[Brief explanation of drawings]

Figure 1 is a block diagram of the present invention, Figure 2 is a system configuration diagram of one embodiment, Figure 3 is a configuration diagram of a cell discarding device, Figure 4 is a configuration diagram of a traffic control device, and Figure 5 is a configuration diagram of a three-person system. Figure 6 is a block diagram of a conventional ATM switch. 1...ATM exchange, 2...Discard flag setting means, -Discard flag storage means, -Routing channel, -Buffer, -Overflow detection means, -Cell discard means, -Random number generation means, -Ear receiver attached , ・Cell.

Claims (1)

[Claims] 1) In an ATM switch (1) that converts input information into cells having fixed length information and performs statistical multiplexing, when accepting a call, flags cells that are not strict against cell discard. a discard flag setting means (2) for setting a discard flag, and a discard flag storage means (for storing a flag indicating that the cell can be discarded, set by the discard flag setting means (2));
3) and detecting whether the capacity of the cells temporarily stored in the buffer (5) in the routing channel (4) in the ATM switch (1) exceeds a predetermined capacity. an overflow detection means (6); and a buffer (
5) overflow information and the discard flag storage means (
cell discarding means (7) for discarding cells that may overflow the buffer (5) and can be discarded based on the flag information indicating that the cells can be discarded stored in step 3); A random number is generated in order to randomize the interval of cell discard by the discarding means (7), and information indicating a discard execution period and a discard execution impossible period is output to the cell discard means (7) based on the random number. 1. A traffic control system in an ATM switch, characterized in that it has a generating means (8). 2) The discard flag setting means (2) is an ATM switch (
Based on the call acceptance information (9) input in step 1), it is determined whether the call is subject to discarding, and if it is not strict, the information regarding each cell (10) of the call is set to allow discarding. The ATM according to claim 1, further comprising a flag indicating that the ATM
Traffic control method in switching equipment. 3) The discard flag storage means (3) stores each cell (10)
2. The traffic control system in an ATM switch according to claim 1, wherein a flag indicating that the cell can be discarded is stored together with control information of a routing path related to the cell. 4) The overflow detection means (6) detects a buffer (
5) detecting a signal output by the routing channel (4) when the capacity of the cell exceeds a predetermined capacity, and notifying the cell discarding means (7) that the buffer (5) will overflow; The ATM according to claim 1, characterized in that
Traffic control method in switching equipment. 5) When the cell discarding means (7) receives an overflow signal from the overflow detecting means (6), the signal from the random number generating means (8) indicates a discard execution period;
2. The traffic control system in an ATM switch according to claim 1, further comprising the step of discarding a cell when a discardable flag stored in said discard flag storage means (3) is set. 6) The cell discarding means (7) discards cells for which the discardable flag is not set, and when the discardable flag is set but the signal from the random number generating means (8) indicates a period in which discarding is not possible. 2. The traffic control system in an ATM switch according to claim 1, wherein cells and cell control information are output to the routing channel (4) without discarding the cells.