JPH05344144A - System switching system - Google Patents

Abstract

PURPOSE:To deal with the acceleration of a switch operation and to prevent cells from being lost at the time of changing over a switch. CONSTITUTION:In the case of performing switching to a switch 4 of a standby system while stopping a switch 3 of an active system, an input side switching circuit 2 stops the input of cells to the switch 3 of the active system and performs switching so that the cells can be inputted to the switch 4 of the standby system. An output side switching circuit 9 inhibits the new output of the switch and selects the output on the side of the switch used up to the present. A buffer state monitor circuit of the active system ejects the cells stored in a buffer inside the switch used up to the present, enables the new output of the switch when the empty state of this buffer is discriminated, and instructs switching to the new switch to the output side switching circuit 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system switching system when an ATM switch of an ATM switch is duplicated.

[0002]

2. Description of the Related Art In an ATM (asynchronous transfer mode) switch, normally, a cell in which destination identification information for identifying a destination is added to the head portion of fixed length communication information is input from a plurality of input circuits, and this destination is input. Two ATM switches (hereinafter referred to as switches) that distribute cells to corresponding destination lines based on identification information are used. One is used as a working switch that distributes cells, and the other is the currently used switch. If it becomes unusable, it will be used instead as a standby switch.

In the conventional switch system switching system having such a configuration, the same information is input to the switch in order to switch the switch from the active system to the standby system, and the internal states are kept the same. Furthermore, in order to make the operation of the switch circuits the same, the same clock is input to the active and standby switches, and initialization is performed at the same timing, so that the active and standby switches are always in the same state. deep.

If the state of the switch is the same in the active system and the standby system, including the internal state, when the switch of the active system is switched to use the standby system due to a failure or the like, a cell is lost inside the switch. Will never happen.

[0005]

In the system switching method of the switch according to the above-mentioned conventional method, there is a delay between the active system and the standby system due to the delay due to the elements constituting the circuit of the switch and the wiring connecting the elements. Since a difference occurs, the operation state cannot be the same unless the operation clock of the switch is slowed down to the extent that the difference in delay time can be ignored. That is,
According to the conventional method, it is difficult to realize a high-speed switch, and there is a problem that cells are lost at the time of switching.

[0006]

The system switching system of the present invention is
A cell in which destination identification information for identifying a destination is added to the beginning of fixed-length communication information is input from a plurality of input lines, and cells are distributed to corresponding destination lines based on the destination identification information. An ATM having a configuration in which two switches are provided, one of which is used as a working switch for allocating cells, and the other of which is used as a spare switch instead when the currently used working switch cannot be used. In the exchange, when stopping the currently used switch of the active system and switching to the switch of the standby system, stop the input of cells to the switch of the active system,
An input side switching circuit that switches so that cells are input to the standby system switch, an output side switching circuit that prohibits the output of a new switch and selects the output of the switch side that has been used until now, It discharges the cells accumulated in the buffer inside the switch that has been used until then, monitors whether this buffer is empty, and when this empty state is identified, enables the output of the new switch and switches the output side. A buffer state monitoring circuit for instructing the circuit to switch to a new switch is provided.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 shows an AT to which the system switching system of the present invention is applied.
It is a block diagram which shows one Example of M exchange. In the figure, 1 is an input line to the switch, 2 is a switching circuit on the switch input side, 3 is an active system switch, 4 is a standby system switch, 5 is a cell accumulation buffer in the active system switch, and 6
Is a cell storage buffer in the switch of the standby system, 7 is a buffer state monitoring circuit of the cell storage buffer of the active system, 8 is a buffer state monitoring circuit of the cell storage buffer of the standby system, 9 is a switch circuit on the switch output side, and 10 is This is the output line from the switch.

Then, a cell having a destination at the beginning of fixed length communication information is input to the input line 1 to the switch, input to the switch 3 currently used by the input side switching circuit 2, and the cell storage buffer 5 is input. Accumulated in. afterwards,
Output from the output side switching circuit 9 to the output line 10.

At this time, in the case of switching from the switch 3 to the standby system switch 4 due to a failure of the active system switch 3 or the like or periodical switching, a cell input from the input line 1 is first input to the input side switching circuit 2. Switch 3
Is switched to the standby system switch 4, and in the switch 3, the cells stored in the cell storage buffer 5 inside the switch are discharged to the output line 10 by the output side switching circuit 9.

Meanwhile, in the switch 3, the buffer state monitoring circuit 7 for monitoring the storage state of the cell storage buffer monitors whether or not the cell storage buffer 5 is empty.

Further, in the output side switching circuit 9, the switch 3
Since the output of the switch 4 is prohibited, the cells input from the input side switching circuit 2 are stored in the standby system switch while the cells in the cell storage buffer 5 inside the switch are being discharged. The data will be stored in the cell storage buffer 6.

After that, the buffer state monitoring circuit 7 which has been monitoring the empty state of the cell storage buffer 5 inside the switch identifies the empty state, so that the output side switching circuit 9
Is operated and the output of the switch 4 is permitted, which means that the switch has been switched.

As described above, by operating the spare system switch after discharging the cells in the active system switch, the information in the switch, the cells to be stored, and the switch itself can be synchronized without synchronizing the switch itself. Since switching can be performed, it is possible to cope with speeding up of the switching operation and prevent loss of cells.

[0015]

As described above, according to the present invention, the input is switched from the active system switch to the standby system switch, while the active system accumulated cells are discharged, the standby system accumulates cells and outputs after the completion of the discharge is confirmed. Since it is configured to switch to the standby system, it is possible to cope with speeding up of the switch operation and prevent loss of cells when switching the switch.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an ATM switch to which a system switching system according to the present invention is applied.

[Explanation of symbols]

 1 input line 2 input side switching circuit 3,4 switch 5,6 cell accumulation buffer 7,8 buffer state monitoring circuit 9 output side switching circuit 10 output line

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location 9076-5K H04Q 11/04 M

Claims (1)

[Claims] 1. A cell in which fixed-length communication information is added with destination identification information for identifying a destination at the beginning thereof through a plurality of input lines, and the cell is a corresponding destination based on the destination identification information. There are two switches to distribute to the line of
Currently used in an ATM switch with a configuration in which one is used as an active switch for allocating cells, and the other is used as a standby switch instead when the currently used active switch cannot be used. When stopping the active system switch and switching to the standby system switch, stop the cell input to the active system switch and switch so that the cell is input to the standby system switch. The input side switching circuit to perform, the output side switching circuit that prohibits the output of the new switch and selects the output of the switch side that has been used so far, and the cell accumulated in the buffer inside the switch that has been used so far Discharge, monitor whether this buffer is empty, and if this empty state is identified, permit output of a new switch, and output side switching circuit System switching method characterized by comprising a buffer state monitoring circuit for performing a switching instruction to the new switch.