JP3106652B2 - Switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching device, and more particularly to a switching device for switching between an active unit and a standby unit in a transmission system.

2. Description of the Related Art In recent years, a transmission device has been currently used (WOR
There is a request to have a PROTECT unit in addition to the K) unit. Therefore, a switching device for switching between the working unit and the spare unit is required.

[0003]

2. Description of the Related Art FIG. 4 shows a conventionally known switching device, in which 1 is an active unit, 2 is a spare unit, 3 and 4 are signal loss detection circuits, and 5 and 6 are three-state buffers ( SW1 to SW4 indicate switches.

The active unit 1 includes a switch SW1 for turning on / off data flowing from the terminal S1 to S2, a switch SW2 for turning on / off data from the terminal R1 to the terminal R2, and a signal disconnection detection of data from the terminal S1. Signal disconnection detection circuit 3 and the data from the switch SW1 are turned on / off.
And a buffer 5 for turning off.

Similarly, the spare unit 2 also has
A switch SW3 for turning on / off data from the terminal S1 to the terminal S2, a switch SW4 for turning on / off data from the terminal R1 to the terminal R2, and a buffer 6 for turning on / off data from the terminal S1. Have.

In such a switching device, when switching from the working unit 1 to the standby unit 2 is required for some reason or when a failure occurs in the working unit 1, the switching occurs in the CPU of the optical transmission device (not shown). The two switches SW1 and SW2 of the working unit 1 are turned off and the two switches SW3 and SW4 of the spare unit 2 are turned on by the switch control signal. These switch positions are just opposite to the positions shown.

At this time, since the switch SW1 is turned off in the signal interruption detection circuit 3 of the working unit 1,
In this state, a signal loss is detected, and an alarm is generated from the signal loss detection circuit 3 in spite of normal switching. Therefore, it is determined that the switch SW1 is normally turned off and the inhibit signal INH, for example, When the H-level signal is given to the signal loss detection circuit 3,
The generation of alarm is prohibited. That is, for example, when the switch SW1 is not turned off despite the necessity of switch switching, the inhibit signal INH
Is not generated, an alarm is generated from the signal interruption detection circuit 3 to notify an abnormal state at the time of switching. However, the inhibit signal INH itself is connected to the terminal S2.
Inhibit signal IN
H causes the buffer 5 to enter a high impedance state, blocking the route from the switch SW1 to the terminal S2.

On the other hand, in the spare unit 2, since the two switches SW3 and SW4 are turned on opposite to the positions shown in the drawing, the data from the terminal S1 is output to the terminal S2. The data from the terminal R1 is output from the terminal R2.

[0009]

In such a conventional example, the inhibit signal INH is supplied from the switch SW1 to the signal disconnection detection circuit 3 and from the switch SW3 to the signal disconnection detection circuit 4. Because
The configuration inside the units 1 and 2 has a problem that the scale becomes large and the alarm control takes time.

According to the present invention, two switches for controlling on / off of data in two directions are respectively provided. A signal disconnection detection circuit for detecting a disconnection state of data in one direction at an output side of one switch, and turning on the data. A switch control signal switches between the working unit and the spare unit, each of which has a buffer for turning on / off and a common input terminal and an output terminal for each data, by a switch control signal. It is an object to eliminate the need for an inhibit signal to a detection circuit.

[0011]

FIG. 1 is a block diagram of the principle of a switching device according to the present invention. In the figure, the same reference numerals as those in FIG.

According to the present invention, two switches SW1, SW2; S for controlling on / off of data in two directions, respectively.
W3, SW4, signal disconnection detection circuits 3, 4 on the output side of one of the switches for detecting a disconnection state of one of the data, and buffers 5, 6 for turning on / off the data. Input terminals S1, R1
The active unit 1 and the standby unit 2 having the output terminals S2 and R2 are connected to the switches SW1 and SW2 when a failure occurs in the units 1 and 2 or for other reasons. In the switching device that switches by controlling SW3 and SW4, the two switches SW1 and SW2 in the units 1 and 2;
W3 and SW4 are changeover switches connecting the off sides, and two switches SW1 and SW2 of one of the units 1 and 2 turned off by the switch control signal;
The data in one direction is looped back as data in the other direction via SW3 and SW4 to prohibit the signal break detection circuits 3 and 4 from detecting signal breaks, and the buffers 5 and 6 are set to the open state, and the loopback is performed. The output data from colliding with the output data.

A level adjusting PA is provided between the off sides of the switches SW1 and SW2 and the switches SW3 and SW4.
D7 and D8 may be provided and connected via the PAD7 and PAD8.

Further, a PN signal generating circuit 32 for generating a PN signal to the working unit 1 and the spare unit 2 respectively,
33, selectors 30 and 31 for selecting one of the PN signal generation circuits 32 and 33 and data from the terminal R1.
For example, when a failure occurs in the unit 2, the selectors 30 and 31 of the units 1 and 2 that are turned off are controlled by a switch control signal sent from a CPU (not shown) to generate the PN signal. The circuits 32 and 33 are selected, and the switches SW1 and SW2 of the units 1 and 2;
, The data of the PN signal generation circuits 32 and 33 are folded back as data in the other direction, and
4 and the buffer 5,
6 is kept open to prevent the folded data from colliding with the output data.

In the units 1 and 2 as well, PADs 7 and 8 for level adjustment are provided between the off sides of the switches SW1 and SW2 and the switches SW3 and SW4.
Connection can also be made via ADs 7 and 8.

[0016]

In the operation of the present invention shown in FIG. 1, when a switch control signal is sent from the active unit 1 to the standby unit 2 due to a failure in the active unit 1 and the like, a failure occurs in the active unit. 1 switches SW1 and SW2
Is controlled to be switched off to the opposite side from the illustrated position, and the switches SW3 and SW4 of the spare unit 2 are also controlled to be switched to the on side opposite to the illustrated position.

Therefore, the data from the terminal S1 is supplied via the switch SW3 of the spare unit 2 and the buffer 6 to the current operation.
The data is sent to the terminal S common to the spare unit and the data from the terminal R1 is output to the terminal R2 via the switch SW4.

In the working unit 1, the terminal R
1 is returned via the two switches SW2 and SW1, but the returned data (signal) causes the buffer 5 to enter a high impedance state and cuts off the returned data. Is avoided.

Also, the signal break detection circuit 3 uses the data turned back from the terminal R1 via the switches SW2 and SW1.
Prevents signal disconnection detection, thereby eliminating the need for an inhibit signal.

When there is a level difference between the input data, the level difference can be absorbed by connecting the off sides of the changeover switches via the PADs 7 and 8 for level adjustment. .

The working unit 1 and the spare unit 2 have PN signal generation circuits 32 and 33 and selectors 30 and 33, respectively.
31 and the selector 3 is controlled by the switch control signal.
When the switch from the working unit 1 to the spare unit 2 becomes necessary when a switch control signal is sent, the selector 30 of the working unit 1 generates the PN signal when the switching from the working unit 1 to the spare unit 2 is required. Select circuit 32,
Since the signal of the PN signal generation circuit 32 is sent to the signal disconnection detection circuit 3 and the buffer 5, the signal disconnection detection circuit 3 determines that the level is normal, and the buffer 5 enters a high impedance state to output the PN signal. Since the signal of the generation circuit 32 is cut off, collision with the data from the buffer 6 can be avoided.

Therefore, even if the data from the terminal R1 is in an abnormal state such as disconnection, no signal disconnection is detected and no alarm is generated.

[0023]

Next, an embodiment will be described with reference to FIGS. 2 and 3. FIG. FIGS. 2 and 3 show an embodiment of the switching device according to the present invention shown in FIG. 1. In this embodiment, SONE is used.
T (Synchronous Optical Net)
(work) system optical transmission device.

2 and 3, the same components as those shown in FIGS. 1 and 4 indicate the same function, and 7 and 8 are PADs and 11 and 21 are bipolar unipolar converters (B
/ U), 13 and 23 are unipolar bipolar converters (U
/ B), 12 and 22 are LSIs incorporating signal disconnection detection circuits 3 and 4 and buffers 5 and 6, 30 and 31 are selectors (SEL), and 32 and 33 are PN signal generation circuits.

First, the first embodiment shown in FIG. 2 will be described. In this embodiment, DS based on the SONET system is used.
The data as three signals (44.736 MHz) passes through a switch SW1 to a bipolar unipolar converter (B / B / B).
U) 11, the signal is converted into a unipolar signal and sent to the LSI 12. In the LSI 12, the STS-1 level (51.
84 MHz) and transmitted from the output terminal S2 to the next higher-order group multiplexing unit (not shown).

The data from the input terminal R1 is an LSI
At 12, the signal is converted to the DS3 level, and at the unipolar bipolar conversion unit (U / B) 13, converted to a bipolar signal. The signal is output from the output terminal R 2 via the switch SW 2 to the next lower order group (not shown). Will be.

The spare unit 2 also has the same structure. When the active unit 1 is switched to the spare unit 2, the data from the terminal S1 passes through the switch SW3, and furthermore, the bipolar unipolar conversion unit 21 and the LSI 22 Is transmitted from the common input terminal S2 via the common input terminal R2, and data from the common input terminal
Is converted into a bipolar signal by the unipolar bipolar converter 23, and is transmitted as DS3 level data from the output terminal R2 via the switch SW4.

At this time, in the working unit 1, the switches SW1 and SW2 are switched to the off position, contrary to the illustration, so that the data from the input terminal R1 is transmitted through the LSI 12 and the unipolar bipolar converter 13. Since the signal is sent from the bipolar unipolar converter 11 to the LSI 12 by passing through the switches SW2, PAD7 and SW1, the signal loss detection circuit 3 included in the LSI 12 does not generate an alarm signal for signal loss detection without an inhibit signal. ing. However, the folded data from the bipolar / unipolar converter 11 is cut off by the high impedance state of the buffer 5 so as not to collide with the data from the LSI 22.

The PAD 7 and the PAD 8 are circuits for comparing the levels on the transmission side and the reception side to make the levels coincide with each other, and various currently known circuits can be used. Next, a second embodiment of FIG. 3 will be described. When the working unit 1 is in operation, the working unit 1
Is the same as that of the first embodiment, so that duplicate explanation is avoided.

At this time, in the spare unit 2, the switches SW3 and SW4 are in the OFF position as shown in the figure. For example, the data from the PN signal generation circuit 33 such as the PN20 stage or the PN15 stage is transmitted to the selector 31 and the The switch SW4 via the unipolar bipolar converter 23,
The data is sent from the bipolar unipolar conversion unit 21 to the LSI 22 via the PAD 8 and the switch SW3.

Here, since the signal disconnection detection circuit 4 included in the LSI 22 detects the folded data of the PN signal generation circuit 33, the signal disconnection detection alarm is always performed regardless of the data from the terminal R1. Operate so as not to generate a signal. At the same time, the data of the PN signal generation circuit 33 turned back from the bipolar unipolar conversion unit 21 is cut off by controlling the buffer 6 to the high impedance state, and does not collide with the data output from the LSI 12.

Next, when the working unit 1 is switched to the spare unit 2, the switch SW of the working unit 1 is switched.
1 and SW2 are switched to the OFF position, but the selector 30 selects the PN signal generation circuit 32 and the data of the PN signal generation circuit 32 is looped back to the LSI 12, so that the signal disconnection detection circuit 3 outputs the data of the terminal R1. Regardless,
No level break is detected.

[0033]

As described above, according to the present invention,
When switching between the active unit and the standby unit of the switching device,
Since the data is folded back through the switch of the unused unit and is configured not to collide with the data passing through the unused unit, the signal interruption detection circuit does not generate an alarm. Therefore, a circuit for performing the inhibition can be omitted, which can contribute to a reduction in circuit scale and cost.

In the case where instantaneous interruption or large level fluctuation occurs in the data to be turned back, a PN signal generating circuit and a selector are provided, and the signal of the PN signal generating circuit is turned back to generate an alarm of the signal break detecting circuit. Can be prevented. Note that the PN signal generation circuit and the selector can be realized on a small scale and can be easily incorporated in an LSI, which can contribute to a reduction in circuit scale and cost.

Further, even if there is a level difference in the folded data, a PAD can be provided and the level can be adjusted, so that the signal break detection circuit can be operated stably.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a switching device according to the present invention.

FIG. 2 is a first embodiment of a switching device according to the present invention.

FIG. 3 is a second embodiment of the switching device according to the present invention.

FIG. 4 is an example of a conventional switching device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Working unit 2 Spare unit 3, 4 Signal loss detection circuit 5, 6 Buffer (three-state buffer) 7, 8 PAD 11, 21 Bipolar unipolar conversion part (B / U) 12, 22 LSI 13, 23 Unipolar bipolar conversion part ( U / B) 30, 31 Selector (SEL) 32, 33 PN signal generation circuit SW1-SW4 Switch

Claims (4)

(57) [Claims] 1. Two switches (SW1, SW2; SW3) for controlling on / off of data in two directions, respectively.
SW4), a signal disconnection detection circuit (3, 4) on the output side of one switch for detecting a disconnection state of one data, and a buffer (5, 6) for turning on / off the data, respectively. , Common input terminals (S1,
R1) and the active unit (1) having the output terminals (S2, R2) and the spare unit (2) when a failure occurs in the unit (1, 2) that is controlled to be turned on, or for any other reason. In the switching device that switches by controlling the switch (SW1, SW2; SW3, SW4) transmitted by the switch control signal, the two switches (SW1, SW1) in the unit (1, 2) are switched.
SW2; SW3, SW4) are changeover switches connecting the off sides, and the two switches (SW1, SW2; SW3, SW3) of one of the units (1, 2) turned off by the switch control signal. SW4), the data in one direction is looped back as data in the other direction to inhibit the signal loss detection circuit (3, 4) from detecting a signal loss,
A switching device, wherein the buffer (5, 6) is opened to prevent the folded data from colliding with output data. 2. The working unit (1) according to claim 1, wherein:
And switches (SW1, SW2;
SW for level adjustment between the off sides of SW3 and SW4)
D (7, 8) provided and connected via the PAD (7, 8). 3. A PN signal generating circuit (32, 33) for generating a PN signal in each of an active unit (1) and a standby unit (2), and the PN signal generating circuit (32, 33). And a selector (30, 31) for selecting one of the data from the terminal R1 and the selector (30, 31) of one of the units (1, 2) turned off by the transmitted switch control signal. )
To select the PN signal generation circuit (32, 33) and switch (SW1, SW) of the unit (1, 2).
2; SW3, SW4), the data of the PN signal generation circuit (32, 33) is turned back as data in the other direction, and the signal break detection circuit (3, 4) inhibits the signal break detection. A switching device for opening the buffers (5, 6) to prevent the folded data from colliding with output data. 4. The switch according to claim 3, wherein the working unit (1) and the spare unit (2) are provided with switches (SW1, S2).
W2: A switching device characterized in that a PAD (7, 8) for level adjustment is provided between the off sides of SW3 and SW4) and connected via the PAD (7, 8).