JPH1198147A - Atm exchange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute quick band change processing by periodically collecting the information of a usable band in a virtual channel(VC) route terminating side direction, and when a band change request is generated, estimating the increasable maximum band of the VC route from the collected information by operation. SOLUTION: At the time of receiving a band change request, a request band reading part 3-1 extracts the requested band and sends the extracted band to a comparing/judging part 4-1. The comparing/judging part 4-1 sends a trigger to a maximum band calculation part 4-2 and calculates a current increasable maximum band. A maximum band calculation part 4-2 calculates an increasable maximum band at optional time based on the information of a maximum using rate on a VC route which is periodically applied. The calculation part 4-2 sends the current increasable maximum band to the comparing/judging part 4-1. The comparing/judging part 4-1 compares the increasable maximum band with the requested band, and when the increasable maximum band is larger, judges that the request can be received and informs a response RM cell generation part 3-4 of acknowledge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode (asynchronous transfer mode). In particular, the present invention relates to a technology for processing a bandwidth change request from a terminal device.

[0002]

2. Description of the Related Art In ATM, all information is written and transferred in fixed-length packets called cells. An ATM terminal device (hereinafter, referred to as a terminal device) establishes a connection with a terminal device as a communication partner via an ATM switching device (hereinafter, referred to as a switching device). This connection is V
It is set by a VC route on P (Virtual Path). The bandwidth of the connection is variably allocated according to the status of the VP free bandwidth. By performing such flexible bandwidth allocation, an ATM communication network (hereinafter, referred to as a network) is provided.
Can be used effectively.

[0003] This conventional example will be described with reference to FIG. FIG. 7 is a sequence diagram showing a conventional band changing process. It is assumed that a connection has already been established between the terminal device 1-1 and the terminal device 1-2 via the switching devices 2-1 to 2-3.

At this time, when a band change request is transmitted from the terminal device 1-1 to the network by an RM (Resource Management) cell, which is a control cell, each switching device 2-1 to 2-2 on the connection is transmitted. At -3, a band change request is read. Each of the switching devices 2-1 to 2-3 determines whether the terminal device 1-1 can accept a bandwidth change request. At this time, if a bandwidth change request can be accepted, the reservation of the bandwidth is also performed. The result of the acceptability determination and the reservation status of the bandwidth are written as bandwidth change availability information in the RM cell and returned to the terminal device 1-1.

[0005]

In such a conventional technique, a band change request by an RM cell issued from an originating terminal arrives at a destination terminal, and an ACK response is returned. Unable to transfer cells in the changed band. Therefore, in a network having a long delay such as a WAN (Wide Area Network), the waiting time from when the originating terminal device issues a bandwidth change request to when the bandwidth change availability information is received is long, and the bandwidth is quickly changed. Can not do.

[0006] Further, in the prior art, only information of acceptance permission or rejection is given as band change availability information, so when a wider band is required or when a re-request is made, how much bandwidth is required. The terminal device cannot know the standard of whether to make the request.

In other words, the terminal device side cannot know how much the requested bandwidth rejected for reception is excessive in view of the band permitted for reception, so the requested bandwidth is gradually narrowed. However, it is necessary to repeat the re-request many times.

In addition, each time a re-request is made, the RM cell originating from the originating terminal device returns to the terminating terminal device. For this reason, when in the congestion state, the request and rejection with a large delay are repeated many times, and the inefficient band changing process is performed from the viewpoint of effective use of the network.

The present invention has been made in such a background, and is capable of performing a rapid band changing process.
It is an object to provide a TM switching device. The present invention
It is an object of the present invention to provide an ATM switching device that performs a band change process so that a terminal device that has issued a band change request can know the difference between its own requested band and an actually increaseable band.
According to the present invention, it is possible to immediately assign a bandwidth equal to or greater than the current assigned bandwidth to the terminal device that has issued the bandwidth change request.
It is an object to provide a TM switching device. The present invention
An object of the present invention is to provide an ATM switching device capable of effectively utilizing a network.

[0010]

According to the present invention, an exchange apparatus is provided in which
The most main feature is to calculate the maximum bandwidth that can be increased in the C route. Further, when the ATM exchange device responds to the band change request from the calling terminal device, the ATM exchange device responds not only with the acceptance permission or rejection but also with information on the acceptable band. I do.

In the "ATM communication network" proposed by the applicant of the present invention in Japanese Patent Application No. Hei 9-135267 (not disclosed at the time of filing the present application), when the use state of the VC route is notified only intermittently to the originating exchange. Also, there is disclosed a technique of interpolating and estimating the use status of a VC route and determining a bandwidth for each connection. However, Japanese Patent Application No. Hei 9-13526
No. 7 does not disclose an acceptance determination technique and a response technique when there is a dynamic band change request from a terminal device.

That is, the present invention relates to an ATM switching device, which is located at one connection point on a VC route set between a calling terminal device and a called terminal device, and which is generated from the calling terminal device. An ATM switching device comprising means for changing a bandwidth of the VC route in accordance with a bandwidth change request on the VC route. The feature of the present invention is that the VC
Means for periodically collecting information on the available bandwidth in the destination direction of the route regardless of the presence or absence of a bandwidth change request, and calculating and estimating the maximum increaseable bandwidth of the VC route from the information when a bandwidth change request occurs. Means.

When the ratio of the usable bandwidth to the VP link capacity is a maximum utilization rate 、, and P1 and P2 are parameters determined by the properties of the network,
The means for calculating and estimating includes means for calculating the increase / decrease ratio γ according to γ = P1 × Ψ + P2, and calculating the maximum band R ′ that can be increased in the VC route as R ′ = R × γ when the current band is R. It is desirable to include means for performing The sum of the parameters P1 and P2 is the target maximum usage rate Ψ
Can be defined as the value of Parameter P1
, The degree of change of the increase / decrease ratio γ with respect to the change of the maximum usage rate Ψ can be adjusted. In addition, the degree of the magnitude of the overall increase / decrease ratio γ can be adjusted by the value of the parameter P2. These parameters P1 and P2
May be set as appropriate according to the nature of the network.

Here, in the present invention, the required band re and the V
A comparison is made with the maximum bandwidth R 'that can be increased in the C route. If re≤R', acceptance is permitted, and if re> R ', acceptance is refused. It is preferable to include means for notifying the value of the maximum band R 'that can increase the VC route to the terminal device on the calling side.

[0015] That is, since the originating terminal device can obtain information on the maximum band R 'that can be increased in the VC route, even if the reception is rejected, the information on the band permitted to be received is known. be able to. As a result, the next band change request can request a band permitted to be accepted. Therefore, the terminal device on the calling side can eliminate the waste of repeating the bandwidth change request through trial and error until the bandwidth change request is accepted as in the related art. This is desirable from the viewpoint of effective use of the network.

Alternatively, the required bandwidth re is compared with the maximum bandwidth R 'that can be increased by the VC route. If re≤R', the required bandwidth re is approved, and if re> R ', the request is allowed up to the bandwidth R'. It is also possible to adopt a configuration including means for performing the above.

That is, in the terminal device on the calling side, even if the requested bandwidth is not secured, a bandwidth higher than the current bandwidth is secured, so that communication can be performed using the secured bandwidth. If the requested bandwidth is not secured, the terminal device on the calling side recognizes that the secured bandwidth is the maximum bandwidth R 'that can be increased at that time, and therefore, the Without repeated re-requests,
Effective use of the network can be achieved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sequence diagram of the band changing process according to the embodiment of the present invention. FIG. 2 is a block diagram of the switching device according to the embodiment of the present invention. FIG. 3 is a block diagram of the request acceptance determining unit according to the embodiment of the present invention.

The present invention relates to a switching device 2-1, which is located at one connection point on a VC route set between the calling side and terminating side terminal devices 1-1 and 1-2, The switching device 2-1 includes a band setting unit 3-3, which is a unit for changing a band of the VC route according to a band change request on the VC route generated from the terminal device 1-1.

Here, the feature of the present invention is that the maximum usage rate, which is the ratio of the available bandwidth as information on the available bandwidth in the destination side of the VC route to the VP link capacity, is determined by the bandwidth change request. A maximum usage rate receiving unit 4-3, which is a means for periodically collecting data regardless of presence or absence, and a maximum bandwidth calculation, which is a means for calculating and estimating the maximum bandwidth that can be increased in the VC route when a bandwidth change request is generated from the information. Unit 4-2.

When the ratio of the usable bandwidth to the VP link capacity is the maximum utilization rate 、, and P1 and P2 are parameters determined by the properties of the network,
The maximum band calculation unit 4-2 calculates the increase / decrease ratio γ by γ = P1 × Ψ + P2, and when the current band is R, calculates the maximum band R ′ that can be increased in the VC route as R ′ = R × γ. I do. The sum of the parameters P1 and P2 is the value of the target maximum usage rate Ψ.

In the first embodiment of the present invention, the request acceptance determination unit 3
The comparison determining unit 4-1 of -2 compares the requested band re with the maximum band R 'that can be increased in the VC route, and accepts reception if re≤R', and rejects reception if re> R '. .

In the second embodiment of the present invention, the request acceptance determination unit 3
-2, the comparison determination unit 4-1 determines the determination result of the comparison determination unit 4-1 and the maximum bandwidth R 'of the VC route that can be increased.
RM cell generating unit 3 for the response to the calling terminal device 1-1.
Notify via -4.

In the third embodiment of the present invention, the request acceptance determining unit 3
The comparison determination unit 4-1 of -2 compares the required bandwidth re with the maximum bandwidth R 'that can be increased by the VC route, approves the required bandwidth re if re≤R', and if re> R ', the bandwidth is approved. Grant the request up to R '.

[0025]

【Example】

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 to 3 are as described above. FIG. 4 is a flowchart showing the operation of determining whether or not to accept a bandwidth change request according to the first embodiment of this invention.

The terminal device 1-1 on the calling side and the terminal device 1 on the receiving side
It is assumed that a connection has already been established between the switching device 2-1 and the switching device 2-1 on the VC route via the switching device 2-3. However, it is assumed that the band given to the connection, that is, the output band allowed for the terminal device 1-1 is smaller than the terminal device 1-1 currently desires.

The originating terminal device 1-1 transmits the RM cell in which the required bandwidth (10 Mbps) is written to the network through the connection. The switching device 2-1 connected to the terminal device 1-1 detects and extracts the RM cell, and reads the required bandwidth (10 Mbps) written thereon by the required bandwidth reading unit 3-1. The read requested bandwidth is sent to the request reception determining unit 3-2, and the request reception determination unit 3-2 performs request reception determination. The bandwidth setting unit 3-3 sets the reception bandwidth as a result of the reception determination.
At the same time, the determination result is sent to the response RM cell generator 3-
Send to 4. The band setting unit 3-3 sets the output band to the updated band, and prevents traffic from flowing into the network in a band higher than the band permitted by the switching device 2-1. The response RM cell generator 3-4 generates an RM cell on which the determination result is placed, and notifies the terminal device 1-1 of the result.

In order for the request reception determining unit 3-2 to perform the reception determination of the requested band without exchanging signals with the other switching devices 2-2 and 2-3 on the VC route for each request, It is necessary to know the acceptable bandwidth for the VC route.

By using the technology disclosed in Japanese Patent Application No. Hei 9-135267 "ATM communication network", it is possible to determine how many times the current bandwidth can be increased by receiving an intermittent notification by the switching device 2-1. It can be calculated at any time. That is, assuming that the current band is R, the maximum band R 'that can be increased can be calculated as R' = R × γ. However, Japanese Patent Application No. 9
No. 135,267 "ATM communication network" does not disclose a technique for responding to a terminal device requesting a change of a used band.

As shown in FIG. 4, when a request to change the band is received (S0), the requested band reading unit 3-1 reads the value re.
Is extracted and sent to the comparison determination unit 4-1. The comparison determination unit 4-1 sends a trigger to the maximum bandwidth calculation unit 4-2, and calculates the current maximum bandwidth R 'that can be increased (S1). The maximum bandwidth calculation section 4-2 sends the current maximum available bandwidth R 'to the comparison determination section 4-1. The comparison / determination unit 4-1 compares the maximum bandwidth R 'that can be increased with the required bandwidth re (S2), and determines that the maximum bandwidth R' that can be increased is acceptable (S3) if the maximum bandwidth R 'is larger. Otherwise, it is determined that the response cannot be accepted (S4), and the resulting ACK (acknowledge) or NAK (negative acknowledge) is sent to the response RM cell generator 3-4.
(S5).

The response RM cell generator 3-4 places an ACK or NAK on the RM cell and responds to the terminal device 1-1. The maximum bandwidth calculator 4-2 is disclosed in Japanese Patent Application No. Hei 9-135267.
According to the technology disclosed in the above publication, the maximum bandwidth R 'that can be increased can be calculated at any time based on the information on the maximum usage rate on the VC route that is given periodically.

According to the first embodiment of the present invention, the terminal device 1-1
Can respond to the bandwidth change request only by the switching device 2-1 connected to the network, and the long delay time conventionally required for the response can be reduced.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing the operation of determining whether or not to accept a bandwidth change request according to the second embodiment of this invention.
The second embodiment of the present invention has the same configuration as the first embodiment of the present invention. However, in the first embodiment of the present invention, the operation of the request acceptance determining unit 3-2 is performed based on the flowchart shown in FIG. That is, after the reception determination, not only the ACK or NAK, but also the value of the calculated maximum band R ′ that can be increased is notified to the response cell generation unit 3-4, and transmitted to the terminal device 1-1 through the RM cell. Then, both values are notified (S13, S14).

According to the second embodiment of the present invention, when a bandwidth change request is received, the terminal device 1-1 is explicitly notified of how far the bandwidth can be extended. If more bandwidth is needed immediately afterwards, it can be used as a measure of the next required amount. In the case of rejection, the terminal device 1-1 is informed in a clear manner how much bandwidth is accepted and permitted. Therefore, the required amount can be reduced and can be used as a standard when re-requesting. For example, the next request is made at a value equal to or less than the notified maximum bandwidth R 'or a value obtained by multiplying the maximum available bandwidth R' by a safety factor of less than 1.0. Will almost certainly be accepted.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of determining whether or not to accept a bandwidth change request according to the third embodiment of this invention.
The third embodiment of the present invention has the same configuration as the first embodiment of the present invention. However, in the first embodiment of the present invention, the operation of the request acceptance determination unit 3-2 is performed based on the flowchart shown in FIG. That is, the comparison determination unit 4-1
Performs a comparison between the maximum band R 'that can be increased and the requested band re, and uses the minimum value as a reception band as the response cell generation unit 3.
-4 (S22, S23). The response cell generator 3-4 notifies the terminal device 1-1 of the reception band through the RM cell.

According to the third embodiment of the present invention, the terminal device 1-1
Since the request can be allocated a bandwidth that can be increased at that time without being rejected, there is no need to set the bandwidth by repeatedly making a request while reducing the request amount. Therefore, there is an effect that the processing amount is reduced by avoiding the re-request.

[0037]

As described above, according to the present invention,
Only the switching device connected to the terminal device can respond to the bandwidth change request, and the long delay time required for the response can be reduced. Further, after receiving the determination result of the bandwidth change request, the terminal device can know how much bandwidth should be requested when a wider bandwidth is required or when re-request is performed. Alternatively, by making the received band the determination result of the band change request as it is,
It is possible to know the information of the band that can be increased and to change the band quickly. As a result, the network can be effectively used.

[Brief description of the drawings]

FIG. 1 is a sequence diagram of a band changing process according to an embodiment of the present invention.

FIG. 2 is a block diagram of an ATM switching device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a request acceptance determination unit according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of determining whether or not to accept a band change request according to the first embodiment of this invention.

FIG. 5 is a flowchart illustrating an operation of determining whether or not to accept a bandwidth change request according to the second embodiment of this invention.

FIG. 6 is a flowchart illustrating an operation of determining whether or not to accept a bandwidth change request according to the third embodiment of this invention.

FIG. 7 is a sequence diagram showing a conventional band changing process.

[Explanation of symbols]

 1-1, 1-2 Terminal device 2-1 to 2-3 ATM switching device 3-1 Requested band reading unit 3-2 Request acceptance determination unit 3-3 Band setting unit 3-4 Response RM cell generation unit 4- 1 Comparison / determination unit 4-2 Maximum bandwidth calculation unit 4-3 Maximum usage rate reception unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayoshi Nabeshima 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. A communication system, which is located at one connection point on a VC (Virtual Channel) route set between a calling terminal device and a called terminal device, and is connected to the VC route generated from the calling terminal device. VC according to the bandwidth change request of
An ATM switching device having a means for changing a bandwidth of a route, a means for periodically collecting information on a usable bandwidth in a destination side of the VC route irrespective of the presence or absence of a bandwidth change request; Means for calculating and estimating the maximum bandwidth in which the VC route can be increased from the information. 2. The VP of the usable band (Virtual P
ath) When the ratio to the link capacity is the maximum utilization rate 、 and P1 and P2 are parameters determined by the properties of the network, the means for calculating and estimating includes means for calculating the increase / decrease ratio γ by γ = P1 × Ψ + P2. 2. The ATM switching device according to claim 1, further comprising means for calculating the maximum bandwidth R 'of the VC route which can be increased when the current bandwidth is R, as R' = R × γ. 3. The sum of the parameters P1 and P2 is
3. The AT according to claim 2, which is a value of a target maximum utilization rate Ψ.
M exchange device. 4. A reception acceptability judging means for comparing a required band re with a maximum band R 'which can be increased by the VC route, and accepting if re≤R' and rejecting acceptance if re> R ', 3. The ATM switching apparatus according to claim 2, further comprising: means for notifying the determination result of said reception availability determination means and the value of the maximum bandwidth R 'of the VC route which can be increased to said terminal equipment on the calling side. 5. A request bandwidth re is compared with a maximum bandwidth R 'that can be increased by the VC route. If re≤R', the required bandwidth re is approved, and if re> R ', a request is allowed up to the bandwidth R'. And means for performing
An ATM switching device as described.