JPH11136256A - SVC setting and assigned bandwidth value assignment method in ATM network - Google Patents

Abstract

(57) [Summary] In the prior art, if there is a vacant band in an ATM transmission line, the SVC band is allowed without any limitation, so the capacity of the vacant band is reduced, and a new PVC is connected. May be unable to connect when needed.
Also, even if a free band occurs, it is used for SVC connection and P
There is a case where a chance to make a VC connection is not given. An SVC restricted band value is set in order to limit a band that can be used by an SVC within a transmission path band. SVC
The band limit value is set according to the transmission path band use status. In order to update the SVC bandwidth limit value to be reduced while the ATM network is operating, the used SVC is released, and waits until the used SVC becomes equal to or less than the updated SVC bandwidth limit value and a free bandwidth is created.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to securing an allocated band in a transmission line in an ATM network,
This relates to securing a VC priority allocation band.

[0002]

2. Description of the Related Art In an ATM network, for each VC (virtual circuit) provided between end systems, a service class (priority of traffic flowing into a transmission line) and a condition of an allocated band (peak value =
PCR, actual use value = SCR, minimum value = MCR) Apply other parameters to the network side (ATM exchange),
The network side compares the application content with the current network usage status to determine whether it can be accommodated,
Provide and maintain the quality of service required for the application, if available. What is particularly important in determining whether or not accommodation is possible is whether the requested allocated bandwidth is equal to or less than the available bandwidth. The allocated bandwidth is determined for each service class, and the CBR (fixed rate) service is PCR, RT
-VBR (Real Time Variable Rate) service is PCR,
The NRT-VBR (non real-time variable rate) service is SCR, and the ABR (available rate) service is MCR. The UBR (no speed specification) service does not specify an allocated bandwidth. For example, if the available bandwidth in the transmission path is 10 Mbp
In the case where the requested bandwidth is 15 Mbps, the request is not permitted because the requested bandwidth is equal to or greater than the free bandwidth. When the allocated bandwidth requested under the same condition is 8 Mbps, the request is permitted because the requested bandwidth is less than the free bandwidth. However, the end system does not always transmit the traffic according to the allocated bandwidth, and the traffic may flow into the network beyond the allocated bandwidth. In the conventional method, it is possible to allocate a bandwidth as long as the bandwidth does not exceed the physical capacity of the transmission path. Since the bandwidth capacity allocated to the SVC is not limited, all the bandwidths other than the PVC bandwidth in the transmission path are allocated as the SVC bandwidth. It was possible.

[0003] However, PVC has a high possibility of transferring more important data than SVC which performs line connection before communication is started due to the property of performing line connection in a fixed manner, so that it is highly necessary to secure an allocated band. Nevertheless, in the above prior art, in order to allocate all the bands other than the band allocated to the PVC in the transmission path without limitation as the SVC band, when applying to the network side to connect a new PVC, There is a possibility that the connection of a new PVC is rejected because there is no available band. Even if some VCs of the SVC connection are released and a free band for connecting a new PVC is created, if a new SVC connection is made immediately, a new PVC is created.
There is no opportunity to make a VC connection.

[0004]

In the above prior art, when a request is made from the end system side to the network side for connection of a new SVC, if there is a free band in the transmission line at that time, it is permitted without restriction. . Therefore, the bandwidth other than the bandwidth allocated to the PVC is occupied by the SVC, and the available bandwidth is reduced, so that it may be impossible to connect when a new PVC needs to be connected.

[0005] An object of the present invention is to improve such a problem and to limit the bandwidth that can be connected by SVC in consideration of the situation of traffic flowing into the network.
An object of the present invention is to provide a method for setting a VC restricted band value.

[0006]

In order to solve the above-mentioned problems, the present invention sets an SVC limit band value in order to limit a band allocated to the SVC. As a result, a sufficient free band is secured, and when a new PVC needs to be connected, the free band is used to allocate the PVC band.
In addition, when the available bandwidth required for newly connecting a PVC is small, the bandwidth limit once set can be changed even while the ATM network is operating.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the drawings.

FIG. 1 is a flowchart of an SVC connection process when an SVC restricted band value is given according to the present invention. A is a required allocated band, B is a vacant band in the transmission path band, and C is a vacant band in the SVC restricted band. When making an SVC connection (step 10), the end system requests a connection from the end system to the ATM exchange (step 11). The ATM exchange determines whether the requested traffic capacity A can be accommodated in the free bandwidth B in the transmission path bandwidth (step 12), and if not, notifies the end system of a connection rejection notification (step 15). In the case of accommodating, in the case of the conventional method, the process of (step 13) is not performed, and the connection permission is notified to the end system (step 1).
4) The process is terminated (step 16). In the method of the present invention, it is further determined whether the requested traffic A can be accommodated in the free band C within the SVC restricted band (step 13). The end system is notified (step 15), and connection is permitted if accommodation is possible (step 1).
4), the process ends (step 16).

[0009] By setting the SVC limited band value, the SVC
An example in which the connection is restricted will be described with reference to FIG. FIG. 2 is a graph showing the state of VC assignment in the SVC connection process when the SVC restricted band value is given. The vertical axis is assigned V
It represents the C band, and the total physical capacity of the transmission path is 100 Mbps. Reference numerals 101 to 103 denote VCs connected by PVC, 20
1 to 204 are VCs connected by SVC, 100 is PVC
Band, 200 is the SVC band, 300 is the free band, 400
Is the SVC limited band, t0, t1, t2, t3 (t0 <t
1 <t2 <t3) is time. The number in parentheses to the right of PVC and SVC is the assigned bandwidth rate. The SVC limit band 400 is 35 Mbps. t0
SVC2 which requires 10Mbps assigned bandwidth
01, and there is an available bandwidth 300 for the required allocated bandwidth within the SVC restricted bandwidth 400, so that the SVC 20
1 is connected. Similarly, at t1, the SVC 202 is connected. At t2, an SVC 203 requiring an allocated bandwidth of 15 Mbps is applied, but the connection is rejected because the free bandwidth within the SVC limited bandwidth is 10 Mbps.
At t3, an SV requiring an allocated bandwidth of 10 Mbps
C204 is applied, and there is an available bandwidth 300 for the required allocated bandwidth within the SVC restricted bandwidth 400.
C204 is connected. By setting the SVC restricted bandwidth value in this way, it is possible to secure an available bandwidth for connecting a new PVC.

FIG. 3 is a flowchart of a PVC connection adding process according to the present invention. When a PVC connection is added (step 20), it is determined whether the required allocated bandwidth A is equal to or less than the vacant bandwidth B in the transmission path bandwidth (step 21). Is assigned as a band to be connected by PVC, and a PVC connection is made (step 26). If the required allocated bandwidth A is larger than the free bandwidth B in the transmission path, the SVC restricted bandwidth value for limiting the bandwidth to which the SVC is allocated is equal to the allocated bandwidth A required by the free bandwidth B in the transmission path bandwidth. The setting is made so that the above can be secured (step 22). SVC suddenly
Since it is impossible to release SVC, no new SVC connection is accepted (step 23), and the process waits until the VC in the SVC band is released (step 24). Further, even if the VC of the SVC is released, it is impossible to connect the PVC unless the free bandwidth B in the transmission path bandwidth for the required allocated bandwidth A can be secured. Step 24) It is determined whether the required allocated bandwidth A is equal to or less than the free bandwidth B in the transmission path bandwidth (Step 2).
5) When the following occurs, a PVC connection is made (step 2).
6), end (step 27).

FIG. 4 shows an example in which a new PVC connection is facilitated by setting the SVC restricted band value. FIG. 4 shows a new PVC in which the SVC limit band value is set in the transmission path band.
7 is a graph showing a band allocation status in a transmission line when setting is made. 104 is a VC connected by PVC.
At time t0, when trying to connect a new PVC 104 that requires an allocated bandwidth of 10 Mbps, the SVC limited bandwidth 400 is set, so that the free bandwidth 300 becomes 30.
Since the bandwidth is 10 Mbps and the allocated bandwidth required by the PVC 104 is 10 Mbps, the PVC 104 is connected using the free bandwidth 300 at t1.

[0012] Compared with the conventional method, when an SVC limited bandwidth value is used when there is no available bandwidth to connect when trying to connect a new PVC, the connection is enabled by reducing the SVC limited bandwidth value. 5 and FIG.

FIG. 5 is a graph showing a state of VC allocation in a transmission line when a new PVC is connected in the conventional method. VCs 205 to 206 are connected by SVC
It is. At time t0, a new PVC that requires an allocated bandwidth of 20 Mbps is about to be connected. At t1, the SVC 203 is released, and the free bandwidth 300 becomes 10 Mbp.
Although s could be completed, the allocated bandwidth required to connect a new PVC is 20 Mbps, so that a PVC cannot be connected. At t2, there is a new connection request of the SVC 206 requiring the allocated bandwidth of 10 Mbps, and the free bandwidth 300 was 10 Mbps.
C206 is connected. Even if such a free band is created, a new SVC connection may be made before the PVC connection because the SVC connection is not restricted, and there is a possibility that there is no opportunity to make a PVC connection.

FIG. 5 is a diagram showing a case where a new PVC is connected when the SVC restricted band value is assigned.
6 is a graph showing an assignment status. PVC 10 requiring a new bandwidth of 20 Mbps at time t0
4 is trying to connect. However, since there is no available bandwidth 300 for allocating the PVC, the SVC restricted bandwidth 40
Set 0 to 35 Mbps. At this time a new SVC
Prohibit connection. At t1, the SVC 203 is released and a free bandwidth of 10 Mbps has been created, but the free bandwidth 300 enough to add a PVC connection has not yet been secured. In addition, here, the SV where the allocated bandwidth is 10 Mbps is required.
Even if there is a C connection request, the connection is rejected. t2
SVC 201 is released and free bandwidth 300 becomes 20M
At t3, the PVC 104 is connected using the free bandwidth 300 at t3. By providing the SVC restricted band value in this way, it is possible to prevent the PVC connection from being hindered by the SVC connection.

[0015]

According to the present invention, when PVC and SVC coexist in an ATM network, an SVC limit band value is provided to limit the band to which SVC is allocated, thereby securing an available band for new PVC connection. Becomes possible. In addition, by reducing the SVC bandwidth limit value while the ATM network is operating, it becomes possible to secure a free bandwidth for allocating a bandwidth required for a new PVC connection.

[Brief description of the drawings]

FIG. 1 is a flowchart of an SVC connection process according to the present invention.

FIG. 2 is a graph showing a state of VC assignment in an SVC connection process when an SVC restricted band value is given.

FIG. 3 is a flowchart of a PVC connection adding process according to the present invention.

FIG. 4 is a graph showing a bandwidth allocation state in a transmission line when an SVC restricted band value is set in the transmission line band and a new PVC is set.

FIG. 5 is a graph showing a state of VC allocation in a transmission line when a new PVC is to be connected in the conventional method.

FIG. 6 shows a new P in the case where an SVC restricted band value is given.
6 is a graph showing a state of VC allocation in a transmission line when an attempt is made to connect a VC.

[Explanation of symbols]

A: required allocated bandwidth; B: free bandwidth in transmission path bandwidth; C: free bandwidth in SVC limited bandwidth;
10-16 ... Processing in SVC connection, 20-27 ... PVC
Processing at connection addition, 100 ... PVC band, 101-10
4: VC by PVC, 200: SVC band, 201
-206: VC by SVC, 300: free bandwidth, 4
00: SVC limited band, t0 to t3: time.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Asakawa 810 Shimoimaizumi, Ebina-shi, Kanagawa Prefecture Hitachi Systems Office Systems Division

Claims (2)

[Claims] 1. PVC (fixed connection type virtual circuit) and SVC
In an ATM (asynchronous transfer mode) network in which (switched virtual circuits) are mixed, an upper limit value is set for the total amount of bandwidth allocated by SVC, thereby securing an available bandwidth to allocate to an allocated bandwidth required for PVC connection. Method to do. 2. A new PV while the ATM network is in operation.
If the free bandwidth required for C connection is insufficient,
The upper limit value of the total amount of bandwidth to be allocated is changed, and a new S
A method of rejecting a VC connection request, waiting for the used SVC to be released to become equal to or less than the updated SVC band limit value to make a free band, and securing a free band to allocate to an allocated band necessary for the PVC connection.