JPH0738567A - Call reception control system for atm switching network and atm exchange node - Google Patents

Abstract

PURPOSE:To effectively use the resources of an ATM switching network by reducing the congestion of the ATM switching network caused by the generation of a new call. CONSTITUTION:When the state of an output buffer is judged as an information reference area in the past (S506), the use conditions of the network in the past are read (S509). With the same kind of call as the new call, a band Vs adding maximum declared value violation width and the peak cell rate of the new call is calculated from the data of the use conditions in the past (S510). Assuming that a call with the value of this Vs as the peak cell rate is received, an average waiting cell length Ls of the output buffer is calculated (S511). In the case of Ls<=Dr, this new call violates the declared value, and that call is not received but a call loss is decided so as to prevent the state of the output buffer from chancing into a dangerous area (S512 and S513). In any case except for Ls<=Dr, this new call is received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a call admission control system for an ATM switching network used in a broadband (B-) ISDN which is a next-generation communication network integrating all communication services such as data and moving images. It concerns an ATM switching node.

[0002]

2. Description of the Related Art In recent years, various technological developments have been made to realize B-ISDN. One of the technological developments is the technological development of the ATM switching network. Regarding the call admission control method of this ATM network, internationally, C
CITT Recommendation I. The outline of the processing procedure is shown by 371.

(ATM network call admission control method): For example,
2 and 3 show the CCITT Recommendation I.S. AT by 371
The processing procedure of the call admission control method of M network is shown. In FIG. 2 and FIG. 3, first, an ATM which is going to perform communication
The terminal device 101 transmits a call request (S111) to the ATM exchange 102. The information of the call request at this time includes the traffic characteristics of the connection to be communicated and the required communication quality. Then, the ATM exchange 102 makes a call admission determination (S112) based on the contents of the declaration.

Then, in this call admission determination S112, the resource amount (bandwidth) required for connecting the connection (resource, transmission line) on the route of the connection is predicted from the declared value, If the predicted amount of resources is acceptable, connect the connection and
The TM terminal device 101 is notified of the call acceptance permission (S113). Then, for the first time, the ATM terminal device 101 transmits the cell stream (user information S114) to A
It can be transmitted to the TM network 103.

Then, the ATM switching apparatus 102 sends the cell stream transmitted from the ATM terminal apparatus 101 to the user / user who is negotiated by the call request (S111).
It is checked (policing) by monitoring whether or not the traffic characteristics between the networks are protected (S115).

Then, as a countermeasure when this traffic characteristic is not protected, the violating cell is discarded. Alternatively, a violation tag is added to a violation cell and the network preferentially discards it when congestion occurs. Alternatively, measures such as disconnecting the connection are considered.

(Call admission determination processing): FIG. 4 is a flowchart of the call admission determination processing in the call admission control method of the ATM switching network. In FIG. 4, the declared value indicating the traffic characteristics declared by the user (ATM terminal device) is
The peak cell rate and average cell rate of the connection. Then, the ATM switching network requests the call connection (S201).
When receiving the request, it is determined whether or not a new call can be accepted by referring to the bandwidth management information of the output transmission line (S2).
02-S203).

This judgment is based on whether or not the band of the output transmission line when a new call is accepted can satisfy a predetermined quality regulation value. Such a judgment is also shown in, for example, Document 1: IEICE Spring National Convention, SB-7-6, "Call Admission Control Method in ATM Switching Network", and the like.

If the band of the output transmission line does not satisfy the quality regulation value, it is considered that a new call cannot be accepted and the call loss process is performed (S204). Then, if it is judged from the band management side of the output transmission line that the call can be accepted, then it is judged whether or not the call is admitted from the actual usage side of the output buffer (S
205-S206).

Also in the judgment here, if the actual usage amount of the output buffer exceeds a certain threshold value (for example, 75%) similarly to the judgment in S203, the output buffer cannot secure the required communication quality. Therefore, the call loss process is performed without accepting the new call (S207). Regarding such judgment, for example, Document 2: Japanese Patent Laid-Open No. 4-179337.
It is also shown in the official gazette.

On the contrary, the actual usage of the output buffer is
When it is less than a certain threshold value, the output buffer is regarded as a safe area in which the required communication quality can be secured, and a new call is accepted and a call acceptance process is performed (S208).

(Burst property of communication information): On the other hand, BI
The features of the service provided by SDN are that it is high-speed and wide-band, and that it can be transferred as it is, regardless of the form of information generation, by ATM exchange processing.
In particular, it is possible to statistically multiplex communication information that occurs in bursts, which cannot be handled by conventional networks, and perform efficient information transfer. FIG. 5 is an explanatory diagram of such burstiness of communication information.

The burstiness of the communication information handled here means that, as shown in FIG. 5, the amount of generated information subject to communication changes in time series. Video communication is a typical example of this. Generally, a moving image is encoded by a high-efficiency encoding method based on a prediction method, so that the amount of encoded information increases in a scene with a lot of motion.

Furthermore, the screen changes (scene change 51-
53) Then, since information for one screen is transferred, a large amount of information is instantaneously generated.

[0015]

However, in the above-described conventional call admission control system, the so-called burst traffic (Burst Traffic) in which the state suddenly changes
ffic) is not taken into account.

For this reason, the cell stream transmitted at a rate exceeding the peak cell rate declared by the user becomes a cause of network congestion, which deteriorates the communication quality of other connected calls. There was a problem.

Therefore, there is a demand for a mechanism for solving the above problems.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce congestion of an ATM switching network due to the occurrence of a new call, and to make an AT more difficult than a conventional one.
A call admission control method for ATM switching network and A for effectively using resources (resources, transmission lines, etc.) of M switching network
The purpose is to provide a TM switching node.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, a first aspect of the present invention, in response to a connection request for a new call, band information of a transmission line on a candidate route and a switch on the candidate route. In the call admission control method of the ATM switching network, which determines whether or not to admit the new call based on the actual usage of the cell buffer (for example, an output buffer after the ATM switch), the following characteristic configuration is realized. did.

That is, in response to the connection request for the new call,
A predicting means for predicting whether or not this new call can cause a violation of the declared value due to the burst traffic in the switch cell buffer on the candidate route is provided, and whether or not the new call can be accepted is judged by the prediction result of the predicting means. It is characterized by doing.

As a mode of the predicting means, use result data (for example, peak cell rate for each call type) in which the above ATM switching network (for example, transmission line or switch cell buffer) is used in the past call admission control processing is used. It is preferable to accumulate the maximum declared value violation bandwidth transmitted over and so on and to make the above prediction from this usage record data.

The second aspect of the present invention, in response to a connection request for a new call from the terminal device, bandwidth information of the transmission path on the candidate path and the switch cell buffer on the candidate path (for example,
Based on the actual usage of the output buffer (after the ATM switch, etc.), it is judged whether or not the new call can be accepted.
The TM switching node has the following characteristic configuration.

That is, the usage record data (for example, for each call type) using the ATM switching network (for example, the transmission line or the switch cell buffer) in the call admission control process for the past connection request of a new call from the terminal device. Storage means for accumulating the maximum report value violation bandwidth transmitted over the peak cell rate) and the connection request of the new call, the new call causes a report value violation due to burst traffic on the candidate route. With a predicting means for predicting whether or not it can occur in the switch cell buffer, for the connection request of the new call, using the past use record data, performs the prediction, by this prediction result, It is characterized by determining whether or not the new call can be accepted.

[0024]

According to the call admission control system of the ATM switching network of the first aspect of the invention, it is predicted whether or not this new call can violate the declared value due to burst traffic in response to the connection request of the new call. By judging whether or not to accept the new call based on the prediction result, it is possible to prevent congestion of the ATM switching network due to the violation of the declared value.

Further, the predicting means uses the actual use data in which the ATM switching network has been used in the past call admission control processing (for example, the maximum declared value violation bandwidth transmitted exceeding the peak cell rate for each call type). Etc. is accumulated and the above-mentioned prediction is performed from this usage record data, so that it is possible to handle a call loss that is predicted to have a high possibility of a declared value violation,
It is possible to prevent congestion of the ATM switching network (network etc.) in advance.

Furthermore, by rejecting a call that is considered to have a high possibility of a declared value violation, it is possible to accept a call that is predicted to have a low possibility of a declared value violation.
Even if the threshold is exceeded in the switch cell buffer, all call requests do not have to be lost,
Resources of the ATM switching network can be effectively used.

Also in the ATM switching node of the second invention, in response to a connection request for a new call in the past from the terminal device,
Usage record data using the ATM switching network in the call admission control processing (for example, the maximum declared value violation bandwidth transmitted exceeding the peak cell rate for each call type) is accumulated and used for a connection request for a new call. On the other hand, by judging from the above usage record data as well, by predicting whether or not this new call can violate the declared value due to burst traffic in the switch cell buffer, it is predicted that there is a high possibility of the declared value violation. It is possible to cause a call to be lost and to prevent congestion of the ATM switching network.

Further, by setting the call loss as the new call predicted to have a high possibility of the declared value violation, on the contrary, the new call predicted to have a low possibility of the declared value violation can be accepted.
As a result, even if the switch cell buffer exceeds a certain threshold, it is not necessary to call all call requests as call loss, and the resources of the ATM switching network can be effectively used.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a call admission control system for an ATM switching network and an ATM switching node according to the present invention will be described with reference to the drawings.

(Outline of One Embodiment): AT of this One Embodiment
In the call admission control system of the M network, in order to solve the above-mentioned conventional problems, the call admission control process of the new call does not make a call admission determination based only on the user's declared value. As the material (element), the information on the usage status of the user's past network is used and used as a new parameter.

The new parameter of this embodiment is, among other usage conditions of the network in the past, the band of cells transmitted in excess of the peak cell rate declared by the user,
That is, the declared value violation bandwidth is used.

By incorporating such a new parameter (reported value violation bandwidth) into the call admission control processing of a new call, it is presumed that the following operation can be obtained. That is, in the conventional call admission control processing, a new call is admitted if the bandwidth management information of the output transmission path and the actual usage amount of the output buffer satisfy the specified threshold values.

However, if this new call violates the declared value due to the above-mentioned burst traffic, the bandwidth of the output transmission line and the usage amount of the output buffer increase due to the burst traffic. The specified threshold may be exceeded.

As a result, the congestion of the network is caused by the declared value violating cells which are transmitted in excess of the peak cell rate, and the communication quality of other calls is deteriorated.

It is considered that there will be no problem if the occurrence of this bursty traffic is predicted in advance on the user side or the network side and some measures (measures) are taken, but the burstiness of this traffic is predicted. That is said to be very difficult with current technology.

Therefore, by incorporating the declared value violation bandwidth of the cell transmitted in violation of the declared value in the above into the processing of the call admission control, the network congestion due to the unpredictable burst traffic is caused. It is thought that this can be prevented.

In the above description, the call type of the new call and the call type of the past data to be referred to are the same. The call type is, for example, a type having similar traffic characteristics and required communication quality.

The call type handled here does not relate to the cell transfer delay or the communication quality expressed by the cell discard rate, but is large in terms of traffic characteristics, and has a fixed rate (CBR: Constant Bit Rate) service. And variable speed (VBR: Variable Bit)
Rate) service.

In the VBR, the call types are classified into types such as a moving picture transfer service and a data transfer service due to the difference in traffic characteristics.

In this embodiment, it is premised that the traffic characteristics of the same call will be similar to past data to some extent.

(Structure of ATM Switching Node): FIG. 6 is a functional block diagram of the ATM switching node 401 according to an embodiment.
In FIG. 6, this ATM switching node 401, when there is a call connection request from the ATM switch 402 that performs switching processing and the ATM terminal device 411, controls whether or not to accept the new call. Processing unit 403
And a line interface device 404 that notifies the call admission control processing unit 403 of the declared value from the user and monitors whether the declared value is observed, and the cell that has been exchange-processed by the ATM switch 402 is buffered. It is composed of a plurality of output buffers 405 and a network usage status storage device 406 that stores the usage status of the network of the user several times in the past.

In FIG. 6, a plurality of ATM terminal devices 411 are connected to the ATM switch 402, and cells sent from the ATM terminal device 411 are ATs.
After being exchange-processed by the M switch 402, they are temporarily buffered in the output buffers 405 of the respective destinations, sent out to the output transmission line 412, and transmitted to the called terminal device.

Further, the ATM terminal device 411 is
It is also connected to the call admission control processing unit 403 through the line interface device 404, and the ATM terminal device 401 provides the call admission control processing unit 403 with declaration parameters such as the traffic characteristics of the call and the communication quality at the time of a call origination request.

Then, the call admission control processing unit 403, which has obtained the declared parameters, is assigned with the current usage information of each output buffer 405, the current allocated bandwidth of each transmission line, and the peak cell rate of the call being connected. Bands, bands allocated at the average cell rate, bands allocated for each call type, etc. are managed, and the call acceptance of a new call is judged by referring to such information.

However, if it is judged that a new call can be accepted only by this condition, when this call violates the declared value due to the burst traffic, the output buffer 405 overflows and the congestion of the output transmission line 412 occurs. This may result in deterioration of the communication quality of other connected calls due to cell discard or the like.

Therefore, after the call admission control processing unit 403 determines that the call can be admitted from the band side of the output transmission line, the call admission control processing unit 403 stores the past network use status of the user from the network use status storage device 406. If data of the same call type as that of the new call is picked up, and if the data has transmitted the cell in violation of the peak cell rate in the past, the call is again taken into consideration in the band of the declared value violation. Admission control processing will be performed.

(Call Acceptability Process): FIG. 1 is a process flow chart for call acceptability of the call admission control system of this embodiment. In FIG. 1, first, the ATM terminal device 411 makes a call connection request to the call admission control processing unit 403. At this time, the ATM terminal device 411 provides the call admission control processing unit 403 with the traffic characteristics of the call to be connected, the required communication quality, and the like as the user declared value (S501).

The call admission control processing unit 403, to which the traffic characteristics of the new call and the required communication quality are given, checks the bandwidth management information of the output transmission line on the path of the new call, and the management information and the user's declared value. From the information, it is determined whether the required bandwidth of the new call can be newly secured in the output transmission line 412 (S502 to S503).

At this time, the band management information of the output transmission line includes the currently allocated band arrow of the transmission line, the band allocated at the peak cell rate of the call being connected, the band allocated at the average cell rate, and the call type. Bands allocated by each are included.

As a result of the call acceptance determination in S503, if the required bandwidth of the new call cannot be newly secured in the output transmission line 412, the call is regarded as unacceptable, and the call is rejected. ATM terminal device 411
Is output to or a call loss process is executed (S50
4).

Then, in step S503, the call admission control processing unit 403, which has determined that the new call can be admitted from the band side of the output transmission path 412, then executes the realization of the output buffer 405 on the path of the new call. Check the usage information Lt (S
505).

The value of the amount of use of the output buffer 405 at this time is not the instantaneous waiting cell length, but the average waiting cell length is used in particular. This is because if the average waiting cell length is large, it is difficult to absorb bursty traffic in the buffer, and there is a possibility that discard will occur immediately.

Then, the average waiting cell length of the output buffer 405 is referred to a table determined in advance as a threshold value for each area and compared with these tables to perform call admission control again (S506).

Then, here, the threshold value of the output buffer 405 is divided into three areas: a dangerous area: Dr, a safe area: Sr, and a past information reference area 71. This state is shown in FIG.

If the average waiting cell length of the output buffer 405 is equal to or larger than the dangerous area: Dr, it is determined that the output buffer 405 cannot secure the required quality of the new call, and the new call is not accepted. Similar to S504, call loss processing is performed (S507).

On the contrary, if the average waiting cell length of the output buffer is within the safe area: Sr, the output buffer 405 determines that the required quality of the new call can be ensured, and the process of accepting the new call is performed. Then, this process outputs information indicating acceptance of a new call to the ATM terminal device 411 (S508).

Next, it can be considered that the average waiting cell length of the output buffer 405 is a region which is neither the safe region: Sr nor the dangerous region: Dr. Such an area is a temporary safe area in the state before accepting a new call, but when a new call violates the declared value due to burst traffic,
It is assumed that when the call is accepted, the state of the output buffer 405 may change to the dangerous area.

Here, the characteristic output buffer 40
The process of trying to prevent the state of 5 from changing to the dangerous area will be described below. That is, when the state of the output buffer 405 is determined to be a past information reference area in S506, the call admission control processing unit 403 reads the past network usage status of the user from the network usage status storage device 406. (S509).

Then, the network use status storage device 406 stores the use band of each of the user's past several call types and the band of the cell transmitted in violation of the declared value at that time.
An example of this stored content is shown in FIG.

Next, referring to FIG. 1, the call admission control processing unit 4
03 is the same call type as the new call from the read network usage data of the user, at which time the cell with the largest cell bandwidth transmitted in violation of the declared value is selected and the maximum Violation of declared value: Hmax
And the peak cell rate of the new call are added: Vs
Is calculated (S510).

Then, the call admission control processing unit 403 calculates the average waiting cell length: Ls of the output buffer 405 on the assumption that the call having the calculated band: Vs value as the peak cell rate is accepted (S511). ).

If the calculated value: Ls is included in the dangerous area: Dr of the output buffer 405 described above, the state of the output buffer 405 is changed due to the declared value violation that this new call may make. In order to avoid changing into the dangerous area, the call is not accepted and the call is lost as in S507 described above (S512, S513).

On the contrary, if the calculated value: Ls is not included in the dangerous area: Dr of the output buffer 405, the status of the output buffer 405 will be changed even if the declared value may violate this new call. Assuming that the required quality of the call can be maintained, the call is accepted as in S508.

Through the processing of S501 to S514 of FIG. 1 as described above, it becomes possible to take into account the declared value violation due to the burst traffic of the call in the processing of the call admission control, and thereby the network due to the declared value violation. Congestion can be prevented in advance.

Also, by making the call loss the call that may violate the declared value, it is possible to accept the call that is unlikely to violate the other declared value, thereby saving network resources. It can be used effectively.

FIG. 7 is a diagram showing the threshold value of the output buffer 405 of the embodiment. In FIG. 7, each of the output buffers a to n of the output buffer 405 has, for example, a safety risk area Sr when cells are buffered.
Or a dangerous area Dr can be represented, and characteristically, the past reference area 71 is provided. The cell buffering amount in FIG. 7 is up to the portion shown by the arrow 72.

Then, the processing of S509 to S514 of FIG. 1 described above is performed in the past reference area 71 of FIG.

FIG. 8 shows the network usage status storage device 4 of one embodiment.
FIG. 7 is a diagram in which the past network usage status of the user (terminal device) is stored in 06 (FIG. 6). In FIG. 8, the band change of the output transmission cell for the network (ATM switching network) is shown for the call types ac. Then, the declared value band 81 is declared for the call type a. Then, the declared value band 82 is declared for the call type b. Then, the declared value band 83 was declared for the call type c. Then, in the call type b, the maximum declared value violation band Hmax is stored beyond the declared value band 82.

The processing of FIG. 1 described above was performed using this maximum declared value violation band Hmax.

(Effect of one embodiment): A of the above embodiment
According to the call admission control system of the TM switching network and the ATM switching node, the output buffer 405 on the candidate route of the new call is
When a certain threshold is exceeded, the declared value violation due to the burst traffic of a new call is predicted by referring to the bandwidth of the declared value violation of the cells transmitted over the past peak cell rate, and the declared value violation It is possible to prevent the congestion of the network by blocking the call that is likely to occur.

Further, the call which is considered to have a high possibility of the declared value violation is rejected, so that the call which is considered to have a low possibility of the declared value violation can be accepted, whereby the output buffer 405 can be accepted. However, if it exceeds a certain threshold, all call requests are not lost and the ATM
The resources of the switching network (network) can be effectively used.

Therefore, according to the call admission control system of the ATM switching network and the ATM switching node described above, it is possible to contribute to the improvement of communication quality such as moving image communication.

(Other Embodiment): (1) In the above embodiment, FIG. 6 showing the configuration of the ATM switching node 401 is as follows.
This is an example, and the present invention is not limited to this. Other functional configurations may be added without departing from the scope of the present invention.

(2) Further, the processing flow chart of the call admission control of FIG. 1 described above is also an example, and in addition, processing steps may be partially added.

(3) Further, the configuration of each area of the output buffer shown in FIG. 7 is not limited to the configuration of such three areas. It may be configured from more areas and used as a judgment element.

(4) Furthermore, the storage contents of the network usage status storage device 406 of FIG. 8 are not limited to the call type, the declared value band, and the maximum declared value violation band Hmax, but other elements. It may be to memorize with.

[0077]

As described above, according to the call admission control system of the ATM switching network of the first invention, in response to a connection request of a new call, this new call violates the declared value due to burst traffic on the candidate light road. Of the above-mentioned switch cell buffer is provided with a predicting means for predicting whether or not a new call can be accepted based on the prediction result of this predicting means. It is possible to reduce congestion and to effectively use the resources of the ATM switching network.

Further, according to the second invention, a storage means,
With a predicting means, for the connection request of the new call,
The above-mentioned past use record data is used to make the above-mentioned prediction, and whether or not the new call can be accepted is judged based on this prediction result.
It is possible to realize an ATM switching node capable of reducing congestion of the switching network and effectively using the resources of the ATM switching network.

[Brief description of drawings]

FIG. 1 is a processing flowchart for determining whether or not a call can be admitted in a call admission control system of an ATM switching network according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional ATM switching system.

FIG. 3 is an explanatory diagram of call admission control according to a CCITT recommendation of a conventional example.

FIG. 4 is a call reception processing flowchart of a conventional example.

FIG. 5 is an explanatory diagram of burstiness of communication information in a conventional example.

FIG. 6 is a functional configuration diagram of an ATM switching node according to an embodiment.

FIG. 7 is an explanatory diagram of threshold values of the output buffer according to the embodiment.

FIG. 8 is an explanatory diagram of stored contents of past network usage status of a user according to an embodiment.

[Explanation of symbols]

401 ... ATM node, 402 ... ATM switch, 40
3 ... Call admission control processing unit, 405 ... Output buffer, 406
... Network usage status storage device, 411 ... ATM terminal device, 41
2 ... Output transmission path.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Hamada 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (3)

[Claims] 1. In response to a connection request for a new call, it is judged whether or not the new call can be accepted, based on the bandwidth information of the transmission path on the candidate path and the actual usage of the switch cell buffer on the candidate path. In the call admission control system of the ATM switching network, a prediction for predicting whether or not a new call can cause a violation of a declared value due to burst traffic in the switch cell buffer on a candidate route in response to a connection request for the new call A call admission control system for an ATM switching network, comprising means for judging whether or not the new call can be admitted according to the prediction result of the predicting means. 2. The predicting means accumulates usage record data in which the ATM switching network has been used in a past call admission control process, and makes the prediction from the usage record data. 1. An ATM switching network call admission control system according to 1. 3. In response to a connection request for a new call from a terminal device, the new call for the new call is based on the bandwidth information of the transmission path on the candidate path and the actual usage of the switch cell buffer on the candidate path. In the ATM switching node which judges acceptance or rejection, in response to a past new call connection request from the terminal device, a storage means for accumulating usage record data using the ATM switching network in the call admission control process, and the above new call connection request. In response to the connection request of the new call, the new call is provided with a prediction means for predicting whether or not the declared value violation due to burst traffic can occur in the switch cell buffer on the candidate route. An ATM switching node characterized by making the above-mentioned prediction using the above-mentioned usage record data of (1) and judging whether or not the new call can be accepted based on this prediction result.