JP2720570B2 - Thread switching control method for ATM switch network - Google Patents

Description

The present invention relates to a system switching control method for an ATM switch network of a digital electronic switching system.

[Conventional technology]

The communication path of the conventional digital electronic exchange system was an STM (synchronous transfer mode) system. In each of the duplex communication paths, all calls are assigned time slots in a frame synchronized by a synchronization signal, and the switching process is performed by changing the calls in synchronization.
Therefore, when switching to a spare call path due to a failure or the like,
I just had to switch according to the synchronization signal.

[Problems to be solved by the invention]

The above-described conventional system switching control method for a communication path using a synchronization signal cannot be used for an ATM (asynchronous transfer mode) communication path in which a call divided into short blocks (cells) is passed asynchronously. In addition, the ATM system has a buffer and the like to operate at a high speed of 150 Mb / s class and to avoid collision with other cells due to self-routing in a switch. It is difficult to make the call path of the act system and the call path of the act system that is actually executing call processing exactly the same state (synchronous state). If the system is immediately switched to the standby system, cells staying in the act system will be lost. There is a problem of being discarded.

An object of the present invention is to provide a system switching control method for an ATM switch network that can perform switching to a standby system without causing cells staying in a communication path to be discarded.

[Means for solving the problem]

The system switching control method of the ATM switch network of the present invention includes an ingress counting means for counting the number of passing cells on the ingress side, an egress counting means for counting the number of passing cells on the egress side, the ingress counting means, And two sets of switch means, including a standby system, having switch means for exchanging ATM cells having count match detecting means for detecting a match between the respective count values of the output side counting means,
An incoming line switching unit and an outgoing line switching unit for independently switching the connection between each of the two systems of switching units and each of the incoming line and the outgoing line are provided. When switching to the switch means, the incoming line switching means switches immediately, but the outgoing line switching means switches when the count coincidence detection means of the operating switch means detects coincidence of the count values.

Further, the output side counting means may be configured to count together the number of cells passing through the output side of the switch means and the number of cells discarded inside the switch means.

〔Example〕

 Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. The ATM switch network according to the present embodiment has an ATM switch communication path 1 for performing a cell switching operation corresponding to each of the 0 system and the 1 system.
0, 11 and input counters 20, 21 for counting the number of input cells of the ATM switch communication paths 10, 11, and output counters 30, 31 for counting the number of output cells of the ATM switch communication paths 10, 11. Counting correction circuits 50 and 51 for counting the number of discarded cells inside the ATM switch communication paths 10 and 11 and adding them to the counting values of the outgoing counters 30 and 31, and the counting values and counting correcting circuits of the incoming counters 20 and 21 Match circuits 40 and 41 are provided for detecting a match with the count values of the output side counters 30 and 31 corrected by the counters 50 and 51. In addition, 0
An incoming selector 6 for selecting either one of the system and system 1 ATM switch communication paths 10 and 11 and connecting to the incoming line 61 via the corresponding input counters 20 and 21;
An output selector 7 which selects one of the selectors 11 and connects to the output line 71 via output counters 30 and 31 and an output selector 7 which detects match between the cell count values of the match circuits 40 and 41 when the system switching instruction is received. And a communication path control circuit 9 for instructing the input-side selector 6 and the output-side selector 7 to perform system switching.

Next, the operation will be described. Now, ATM switch communication path 10 (0
System) is an act system. The cell coming from the incoming line 61 reaches the incoming counter 20 via the incoming selector 6 set on the 0-system side, and counts up its count value. Further, after passing through the ATM switch communication path 10, the count value of the output side counter 30 is counted up, and the output goes out to the output line 71 via the output side selector 7 set on the 0-system side.

Here, the ATM switch communication path 11 (system 1) during periodic tests, etc.
Is considered to be the act system, that is, the case where the communication path is switched to the system 1 is considered. When the switching request signal is output from the communication path control circuit 9, the input side selector 6 immediately operates, and the input side counter 6 operates.
21, The cell is switched to the ATM switch communication path 11, and all the cells thereafter flow to the ATM switch communication path 11.

At this point, since there are cells staying in the ATM switch communication path 10, the values of the incoming counter 20 and the outgoing counter 30 are different from each other. That is, the input counter 20
Is larger than the value of the output side counter 30. Inlet counter 20
Is not counted because there are no incoming cells, but the egress counter 30 is counted up for a while because the staying cells in the ATM switch communication path 10 exit.
Since cells are discarded in the ATM switch communication path 10 when the buffer overflows, the value of the ingress counter 20 and the egress counter 30 are reduced by the number of discarded cells.
Is different from the value of. The number of discarded cells is counted by the count correction circuit 50 and added to the count value of the output counter 30 to perform correction. Therefore, after a while, the value of the input counter 20 and the value of the output counter 30 corrected by the count correction circuit 50 become equal. At this time, the match circuit 40 detects a match (detects that the number of staying cells in the ATM switch communication path 10 is “0”), and the output side selector 7 uses the logic of the switching logic circuit 8 to switch the ATM switch communication. Switch to Road 11 side.

On the other hand, the cells input to the ATM switch communication path 11 stay without being output until the output selector 7 is switched, but from the time when the output selector 7 is switched to the ATM switch communication path 11 side. Is output, and system switching is completed.

FIG. 2 is an explanatory diagram showing the operation status at the time of system switching in chronological order. The input side counter 20 stops counting up at the time (t ₀ ) when a switching request is made, and the value of the input side counter 20 is changed. and the value of the outgoing side the counter 30 coincides with the count correction circuit values and the time t ₁ corrected by 50 indicating execution of switching of the outgoing side.

Further, the system switching operation when the ATM switch communication path 11 (system 1) is the act system is performed in the same manner as described above.

If no cells are discarded inside the ATM switch communication paths 10 and 11, the count correction circuits 50 and 51 may not be provided.
In this case, the output side counters 30 and 31 are directly connected to the match circuits 40 and 41, respectively.

〔The invention's effect〕

As described above, the system switching control method of the ATM switch network of the present invention switches the input side selector immediately upon receiving a request for system switching of the communication path, and all the cells staying in the communication path which has been the act system up to now. Since the output side selector is switched after being output, there is an effect that cell discarding due to system switching does not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an operation state at the time of switching in a time-series manner. 6 Incoming selector, 7 Outgoing selector, 8 Switching logic circuit, 9 Communication path control circuit, 10, 11 ATM communication path, 20, 21 Input counter, 30, 31 ... Outside counter, 40,41 ... Match circuit, 50,51 ... Count correction circuit.

Continuation of the front page (56) References JP-A-2-246646 (JP, A) JP-A-64-57852 (JP, A) JP-A-3-44243 (JP, A) JP-A-1-292936 (JP) JP-A-3-26038 (JP, A) JP-A-57-35449 (JP, A) JP-A-2-228148 (JP, A) IEICE Technical Report, Vol. 89, No. 126, SSE89-38, July 19, 1989, p. 37−42

Claims (2)

(57) [Claims] 1. An input side counting means for counting the number of passing cells on the input side, an output side counting means for counting the number of passing cells on the output side, and a total of each of the input side counting means and the output side counting means. There are provided two systems including a standby system and a switch system for exchanging ATM cells having a count coincidence detecting unit for detecting a coincidence of numerical values, and each of the two system switching units is connected to an incoming line and an outgoing line. When switching the active switch means to the standby switch means, the incoming line switch means switches immediately, but the outgoing line switch means switches the connection between them independently. The system switching control method for an ATM switch network, wherein the line switching means switches when the count coincidence detection means of the operating switch means detects coincidence of the count values. 2. The ATM according to claim 1, wherein said output side counting means counts together the number of cells passing through the output side of said switch means and the number of cells discarded inside said switch means. System switching control method for switch networks.