JP3125592B2 - Communication apparatus and communication quality control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used in an ATM (Asynchronous Transfer Mode) communication network. In particular, a simple and efficient VC
The present invention relates to a technology for configuring a network and easily and efficiently controlling the quality of connection by VC.

[0002]

2. Description of the Related Art FIG. 7 shows an example of the configuration of an ATM communication network, and FIG. 8 is a diagram showing a node configuration for controlling the quality of a connection by VC.

In this example, a communication from a subscriber A to a subscriber B is performed by a subscriber exchange 1-1 and a cross-connect device 3-.
1, transit exchange 2-1, cross-connect device 3-2, transit exchange 2-2, cross-connect device 3-3, transit exchange 2-3, cross-connect device 3-4, and subscriber exchange 1-2. It is connected. Each node (subscriber exchanges 1-1 and 1-2, transit exchanges 2-1 to 2-3, and cross-connect devices 3-1 to 3-4) are connected by a transmission line 4. The number of transit exchanges is uniquely determined by the location, regardless of the nature of the traffic such as severe delay.

In order to cope with traffic that is strictly delayed in such a configuration, it is considered that priority control is performed in each passing node including a cross-connect device.
FIG. 8 shows an example of such a configuration. Generally, CLP (Cell Loss Parity) of the header of the ATM cell is used.
ty) Using a bit, each node has the bit "0"
Or, divide each buffer corresponding to "1",
“0” is processed with high priority.

[0005]

However, in the conventional method, since it is necessary to process the CLP bit in each node, it is necessary to perform priority control even in a high-speed cross-connect device or a transit exchange, and the hardware becomes complicated. In addition, there is a disadvantage that the cost increases. In addition, the quality that can be controlled by each relay node is limited to two types. For example, if delay and cell loss rate are controlled, it is necessary to support four classes by a combination of high priority and low priority, respectively. It was not realistic because it would increase the cost.

Further, in the conventional method, the control of communication is closed within the node, and even if the network is relatively free, each node performs priority processing, resulting in deterioration of network efficiency.

An object of the present invention is to provide a communication apparatus and a communication quality control method capable of solving such a problem and controlling communication quality of each connection simply and efficiently.

[0008]

SUMMARY OF THE INVENTION A first aspect of the present invention is a communication device, which includes a plurality of exchanges that perform switching in units of VCs, a cross-connect device that switches the route in units of VPs, and a communication device. A transmission line that physically connects the exchange and the cross-connect device, and a VP network that logically connects the exchange on the transmission line are set up.
A communication device including a means for setting a VC network for logically connecting the subscribers on the VC network, wherein at least a part of the plurality of exchanges includes means for controlling the quality of the connection by the VC. The means includes means for allocating, to a connection by each VC, one or a small number of k ≦ n switches among a plurality of n switches on a path from a start point to an end point of the VC as a switch for controlling the quality of the connection. It is characterized by the following.

[0009] Preferably, the allocating means includes means for selecting an exchange to which a low-speed virtual path is allocated.

[0010] Among the exchanges controlling the quality of the connection, the exchanges assigned as the downstream exchanges of the connection are provided with means for observing the delay of the connection and informing the upstream exchange controlling the quality of the connection. it is as possible out, including.

A switch provided with means for turning back the test cell between the start point and the end point of the virtual channel, and which is assigned as an exchange for controlling the quality of the connection, is provided with an insertion time and a return time stamped on the test cell. Means for observing the delay can also be included.

A second aspect of the present invention is a communication quality control method, which is a communication quality control method for controlling the quality of a connection for logically connecting subscribers by VC through a plurality of switching nodes. One of a plurality of n switching nodes
Alternatively, the quality of the connection is controlled by a small number of switching nodes where k ≦ n. It is preferable to monitor the quality from the start point to the end point of the VC and control the quality of the connection based on the monitoring result.

[0013]

The control of various communication qualities, especially delay and delay fluctuation, is performed by only one or a small number of exchanges, and the operation is determined including the state of the network. That is, the quality is controlled by a small number of nodes (switches), the quality of the connection is communicated between those control nodes, and end-to-
Monitor the quality of the end and improve the quality at the node if the quality deteriorates and the resources of the own node are available, and reduce the resources for the connection at the own node if the quality is too good. In order to effectively use resources for other connections, and to cooperate in the entire network.

[0014]

FIG. 1 is a block diagram showing a communication apparatus according to a first embodiment of the present invention. Here, only the part relating to the connection between the two local exchanges is shown. This device is
A plurality of exchanges that perform switching in units of VCs include subscriber exchanges 11-1 and 11-2 and transit exchanges 12-1 and 12-3, and a cross-connect device 13-1 that switches the route in units of VPs. , 13-3,
13-4, and a transmission line 14 for physically connecting them.
Operating system as an upper means for setting a VP network for logically connecting a plurality of exchanges on the transmission line 14 and setting a VC network for logically connecting subscribers on the VP network. 16 is provided. Local exchanges 11-1 and 11-2 and transit exchanges 12-2 and 12-
3, at least in this example, the local exchange 11-1.
And the relay exchange 12-3 have priority control circuits 15-1 and 15-1 as means for controlling the quality of the connection by VC.
5-2. The priority control circuits 15-1 and 15-2 store cells of various classes having different allowable delay amounts and allowable delay fluctuation amounts at constant speed V in accordance with the required quality.
In order to transmit the cells to P, a shaper for temporarily storing the cells for each class is provided. Here, the feature of the present embodiment is that the operation system 16 includes, as an exchange for controlling the quality of the connection for each VC, among the plurality of n exchanges on the path from the start point to the end point of the VC. It is intended to include program means for allocating a small number of exchanges where 1 or k ≦ n.

That is, in this example, the subscribers A and B are connected from the subscriber exchange 11-1 to the cross-connect device 13-1,
.., Cross-connect device 13-
3, transit exchange 12-3 and cross-connect device 13
VC terminated at the local exchange 11-2 via -4
Are connected logically, and the quality control of the connection is performed by the local exchange 11-1 and the transit exchange 12-3.

In such a configuration, the cross-connect devices 13-1, 13-3, and 13-4 need not distinguish cells at all, and can be configured with simple switches.

FIG. 2 is a diagram for explaining the delay time in the communication from the subscriber A to the subscriber B. Each node (subscriber exchange 1)
1-1, cross-connect device 13-1, transit exchange 12
-1,..., Cross-connect device 13-3, transit exchange 1
2-3, cross-connect device 13-4 and subscriber exchange 11-2) The delay time at the time of passing is represented by the M / D / 1 model, that is, the arrival process is a Poisson process, and each subscriber makes a random call, The multi-pass characteristic is shown when the service process is a fixed time service and the number of servers is one.
Only the local exchange 11-1 and the transit exchange 12-3 perform priority control, but the end-to-end delay from the subscriber A to the subscriber B is sufficiently controlled by these two switching nodes.

FIG. 3 shows the relationship between the VP speed and the delay time at the node. In a node where a large amount of traffic is collected, for example, the relay exchanges 12-1 and 12-2, the transfer speed of the VP is high, and the delay time is small. Therefore, efficient quality control can be performed by controlling delay and delay fluctuation with a small number of exchanges to which low-speed VPs are assigned.

FIG. 4 is a block diagram showing a communication apparatus according to a second embodiment of the present invention. Here, only the configuration between the two exchanges 21-1 and 21-2 for controlling the quality is shown. The exchanges 21-1 and 21-2 are each provided with a priority control circuit 25-.
1, 25-2, and furthermore, control circuits 27-1, 27-
2 is provided. These control circuits 27-1 and 27-2 are:
When an exchange controlling the quality of a connection is assigned as an exchange on the downstream side of the connection, the switch monitors the delay of the connection and notifies the upstream exchange controlling the quality of the connection. This notification is performed via the operation system 26. The control circuits 27-1 and 27-2 also control the priority control circuits 25-1 and 25-2 according to the notification from the downstream exchange when assigned as the upstream exchange.

Next, the operation of this embodiment will be described by taking as an example the case where the exchange 21-1 is set to the upstream side and the delay in the exchange 21-2 starts to increase. When the delay has increased, the traffic of the exchange 21-2 has increased in many cases. For this reason, increasing the speed of the corresponding shaper even if the delay is large has a great effect on other connections using the same transmission path. Therefore, the control circuit 27-2 notifies the upstream exchange 21-1 of the operation state via the operation system 26. This notification is sent to the control circuit 27-1 of the exchange 21-1.
If the operation of the exchange 21-1 has a relatively margin, the delay is reduced by operating the priority control circuit 25-1. Thereby, end-to-end quality can be maintained.

FIG. 5 is a block diagram showing a communication apparatus according to a third embodiment of the present invention. This figure also shows only a part related to quality control. Here, the subscriber exchange 31-
VC is set between the relay exchange 1 and the relay exchange 32-1.
1, 32-2 perform quality control. The local exchange 31-1 includes a test cell insertion circuit 38-1, and the local exchange 31-2 includes a test cell return circuit 38-2. The relay exchanges 32-2 and 32-2 are provided with control circuits 37-1 and 37-2, respectively, and monitor test cells. The insertion time and the return time are stamped in the test cell, and the quality of the relay exchange 3 is controlled by monitoring the upstream and downstream sides of the bidirectional communication.
In 2-1 and 32-2, the current service status can be known.

FIG. 6 shows the flow of quality control in the third embodiment. In a node that performs quality control, in this case, a control unit (not shown) of the relay exchanges 32-1 and 32-2, if the quality of the connection is superior to the quality target, V
Reduce the speed of P. That means saving resources,
Increase the delay at that node and allocate that amount to another connection or prepare for a new call. On the other hand, if deterioration of the quality is observed and the node has room, the quality is improved to improve the end-to-end quality. In this way, the performance of the entire communication network is determined while feeding back the current operation.

Here, the case where the test cell is used autonomously has been described, but the end-to-end quality can be monitored via the operation system.

[0024]

As described above, according to the communication apparatus and the communication quality control method of the present invention, the quality of the connection is controlled by a small number of nodes (switches), so that a plurality of qualities can be controlled easily and efficiently. Can be. Therefore, there is an effect that a simple and economical communication network can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a communication apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a delay time.

FIG. 3 is a diagram illustrating a relationship between a VP speed and a delay time at the node;

FIG. 4 is a block diagram showing a communication device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a communication device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a flow of quality control.

FIG. 7 is a diagram showing a configuration example of an ATM communication network.

FIG. 8 is a diagram showing a node configuration for controlling the quality of a connection by VC.

[Explanation of symbols]

1-1, 1-2, 11-1, 11-2, 31-1, 31
-2 subscriber exchange 2-1 to 2-3, 12-1, 12-3, 32-1, 32
-2 transit exchanges 3-1 to 3-4, 13-1, 13-3, 13-4 cross-connect device 4, 14 transmission line 15, 25-1, 25-2 priority control circuit 16, 26 operation system 21 -1, 21-2 Switchboard 27-1, 27-2, 37-1, 37-2 Control circuit 38-1 Test cell insertion circuit 38-2 Test cell return circuit

Continued on the front page (56) References IEICE technical report SS E93-41 (September 30, 1993) IEICE technical report SS E92-176 (March 17, 1993) IEICE Technical report of the Society SS E94-47 (May 26, 1994) IEICE Autumn Meeting 1994 B-475 (September 5, 1994) (58) Fields surveyed (Int. Cl. ⁷ , DB name) ) H04L 12/28 H04L 12/56

Claims (5)

(57) [Claims] 1. A plurality of exchanges that perform switching in units of a virtual channel (VC), a cross-connect device that switches its route in units of a virtual path (VP), and a physical connection between the plurality of exchanges and the cross-connect device. And a virtual path network (VP network) for logically connecting the plurality of exchanges on the transmission path, and a virtual path for logically connecting subscribers on the virtual path network. A communication device comprising: a high-level means for setting a channel network (VC network); and at least a part of the plurality of exchanges includes a means for controlling a quality of a connection by a virtual channel. As a switch that controls the quality of the connection, Among the starting point of the Virtual Channel switch of the plurality n of paths reaching the end point, the slow virtual path
A communication device, comprising: means for allocating one or more switches that are less than the assigned n . 2. An exchange for controlling the quality of a connection.
Assigned as the downstream switch of the connection
Switch that observes the connection delay
The connection is passed to the upstream exchange that controls the quality of the connection.
Communication apparatus according to claim 1 including means for knowledge. 3. Between a start point and an end point of a virtual channel.
With means to wrap the test cell at the connection quality
The switch assigned as the switch controlling the
Insertion time and return time stamped in the test cell
2. The communication apparatus according to claim 1, further comprising: means for observing a delay of the connection at an instant . 4. Between subscribers via a plurality of n switching nodes
Connect logically by virtual channels
And have you in the communication quality control method for controlling the quality of the ® down, the
Among the plurality of switching nodes, the low-speed virtual path is
Assigned by one or more switching nodes less than n assigned.
Communication characterized by controlling the quality of a connection
Quality control method. 5. A virtual channel from a start point to an end point.
Quality and monitor the connection
5. The communication quality control method according to claim 4, wherein the communication quality is controlled.