JPH0486043A - Redundant switching system for atm switch - Google Patents

Abstract

PURPOSE:To execute the redundant changeover of an synchronous transfer mode (ATM) switch without instantaneous interruption and without abandonning cells by using the idle cell or synchronizing cell of an input data for instructing timing for the write redundant switch of switch information. CONSTITUTION:The switch information received from a high-order control part 2 is written in the idle cell received at a switch information inserting part 1. A supervisory and control part 3 supervises the appearance of the cell for switch control writing the switch information and controls a branching circuit 4 so as to execute switching from an active system switch 5 to an auxiliary system switch 6. The cell for switch control is finally resident at a buffer 51 in the active system switch 5, and the cell following just after is resident at a buffer 61 of the auxiliary system switch 6. When the cell for switch control is received while selecting an output signal S7 from the active system switch 5, the selection is switched to the selection of an output signal S8 from the auxiliary system switch 6. Thus, without abandonning cells resident in the buffer 51 of the active system switch 5 when receiving switch information from the high-order control part 2, the switch can be changed over without any instantaneous interruption.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a redundant switching system for ATM switches, and in particular to ATM switches equipped with a buffer at the output section to avoid cell contention.
Regarding the redundant switching method of switches.

[Conventional technology]

In the conventional redundant switching system of this type of ATM (asynchronous transfer mode) switch, the branch circuit 14 is
The selection circuit 18 directly receives switching information from the upper control unit 12 and simultaneously switches the branch circuit 14 and the selection circuit 18 from one of the active system switch 15 and the standby system switch 16 to the other.

[Problem to be solved by the invention]

In the conventional ATM switch redundancy switching method described above, for example, when switching from the active switch 15 to the backup switch 16, the data remaining in the buffer in the active switch 15 is discarded. There is a problem in that instantaneous interruptions occur.

[Means to solve the problem]

The redundancy switching method of the present invention is based on asynchronous transfer mode (ATM), which has a buffer for temporarily storing cell data.
) for the active system switch and the backup system switch, a switching information insertion unit that writes switching information into cells in input data, and monitors the cells in which the switching information is written and sends them to the active system switch and the backup system switch. a branch circuit that distributes cells to be transferred; a first supervisory control section that controls cell distribution in the branch circuit; a selection circuit that selects cells to be read from the active switch and the backup switch; and a second monitoring control section that controls selection of the selection circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. The difference between this embodiment and the conventional method shown in FIG. The supervisory control units 3 and 7 are provided to control the branch circuit 4 and the selection circuit 8, respectively, while monitoring the control cells. In the conventional system shown in FIG.
Since the switching information transmitted from the switch directly controls the branch circuit 14 and the selection circuit 18, the switch performs switching, so when the switching information is received, the active system switch 5 (or standby system switch) 6
) will be discarded.

In this embodiment, the switching information received from the upper control unit 2 is written into the idle cell received by the switching information insertion unit 1.

The supervisory control unit 3 monitors the appearance of a switching control cell in which the switching information is written, and when a switching control cell is received, controls the branch circuit 4 to switch from the active switch 5 to the standby switch 6. I do. As a result, the switching control cells are accumulated at the end of the buffer 51 in the active switch 5, and the cells immediately following the switching control cells are accumulated in the buffer 61 of the standby switch 6. When the supervisory control unit 7 receives the switching control cell while selecting the output signal S7 from the active switch 5, it switches to select the output signal S8 from the standby switch 6. Thereby, when switching information is received from the upper control unit 2, the cells stored in the buffer 51 of the active switch 5 are not discarded, and switch switching can be performed without momentary interruption.

FIG. 2 is a block diagram of a second embodiment of the present invention. This embodiment has a configuration in which a data erasing section 9.11 is added to the first embodiment (see FIG. 1). When performing redundancy switching, the buffer 61 in the standby switch 6 is made into a state where nothing is written by the data erasing section 11,
Switching information S2 is transmitted from the upper control unit 2 to the switching information inserting unit 1. The switching information insertion unit 1 writes switching information S2 into a vacant cell (idle cell) of data S1.

When the supervisory control unit 3, which monitors empty cells of the data S3 input to the branch circuit 4, detects an empty cell with switching information, it sends the empty cell to the active switch 5, and then outputs the same data as the data S5. The branch circuit 4 is instructed to send the data S6 to the standby switch 6, and the branch port Ft@4
is the same data S for the active switch 5 and the standby switch 6.
5. Send S6 and write in the same way. Here, if we focus on the buffer 51 and its backup buffer 61, we can see that there are cells in the buffer 51 that are earlier in order than empty cells that have switching information, empty cells that have switching information, and cells that are earlier than empty cells that have switching information. The subsequent cells are written as data. In addition, cells that are later in order than empty cells having switching information are written as data in the banner 61. The supervisory control unit 7 monitors the selection circuit 8 that sequentially reads data written in the buffer 51, and when it detects that the selection circuit 8 has read out an empty cell having switching information, it sends a message to the selection circuit. and issues an instruction to switch from the active switch 5 to the standby switch 6. After the switching of the selection circuit 8 is completed, the branch circuit 4 selects the data S5.
stop sending.

After switching to the backup system switch 6, the selection circuit 8 sequentially reads out the data written in the buffer 61 and outputs it as data StO.

The data erasing unit 9 erases data remaining in the buffer 51 of the active switch 5 in preparation for switching back from the backup switch 6 to the active switch 5. Switching back from the standby switch 6 to the active switch 5 is the reverse of the above operation.

If the above procedure is performed, no cells carrying valid data will be discarded, so redundancy switching can be performed without momentary interruption.

FIG. 3 is a block diagram showing a third embodiment of the present invention. In this embodiment, a periodic cell generating section 10 is provided which generates internal control cells at a constant period, multiplexes time division cells with input data S1, writes switching information to this periodic cell, and writes the switching information to the first or second cell. As in the case of the embodiment described above, the active system switch 5 and the standby system switch 6 are mutually switched, and redundant switching can be performed without momentary interruption.

〔Effect of the invention〕

As explained above, the present invention enables ATM switch redundancy switching without a momentary interruption without discarding cells by writing switching information into idle cells or synchronous cells of input data for redundancy switching timing instructions. It has the effect of being able to do the following.

[Brief explanation of the drawing]

1 to 3 are block diagrams showing embodiments of the present invention, and FIG. 4 is a block diagram showing a conventional ATM switch redundancy switching system. 1... Switching information insertion section, 2, 12... Upper control section,
3.7...Monitoring control unit, 4,14...Branch circuit, 5゜1
5... Active system switch, 51... Buffer, 6゜1
6... Backup system switch, 61... Buffer, 7...
・Cell monitoring and selection circuit control unit for switching control, 8, 18・
...Selection circuit, 9.11...Data erasing section, 10...
- Synchronous cell generation section.

Claims (1)

[Claims] 1. An active switch and a standby switch for asynchronous transfer mode (ATM) each having a buffer for temporarily storing cell data, and switching information insertion for writing switching information into cells in input data. a branch circuit that monitors the cells in which the switching information is written and distributes the cells to be transferred to the active switch and the backup switch; and a first monitoring control that controls the cell distribution of the branch circuit. an ATM switch comprising: a selection circuit that selects cells to be read from the active switch and the standby switch; and a second supervisory control unit that controls selection of the selection circuit. Redundant switching method. 2. The redundant switching system for an ATM switch according to claim 1, wherein the cell into which the switching information is written is an empty cell in the input data. 3. Claim (1) wherein the cell in which the switching information is written is a synchronous cell generated at a constant period in the input data.
) Redundant switching method for ATM switches described in ). 4. The AT according to claim (1), further comprising a data erasing section that erases data in the buffers of the active switch and the backup switch prior to control according to the switching information.
Redundant switching method of M switch.