JP3507552B2 - Network synchronous clock selection circuit for private branch exchange. - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network synchronous clock selection circuit for a private branch exchange, and more particularly to a network synchronous clock selection circuit for a building block type private branch exchange divided into a plurality of system racks.

[0002]

2. Description of the Related Art Generally, when connecting a private branch exchange to a digital line, it is necessary to synchronize the internal clock of the private branch exchange with the network synchronization clock of the digital line. Therefore, the clock is extracted from the digital line and used as the internal clock of the private branch exchange.

A conventional private branch exchange having a single system rack and a small number of lines to be connected is, as shown in FIG. 2, connected to a plurality of lines 42, 43 and 44 and to each line 42, 4 respectively.
It has a clock extraction unit 38 that extracts clocks from the signals 3 and 44. The clock extraction unit 38 is connected to the clock selection unit 39 that selects a desired clock based on the selection control signal via the extraction clock lines 45, 46, and 47, and which line can extract the clock? A selection control unit 41 that sends a selection control signal to the clock selection control line 50, which receives information via the clock monitoring line 49 and selects one from the clock extractable lines.
Are connected. The clock selecting section 39 is connected to a clock generating section 40 which converts the clock selected by the clock selecting section 39 into a frequency used inside the private branch exchange and outputs the frequency to the internal clock line 51 via the selected clock line 48. There is.

Next, the operation of this conventional example will be described.

The clock extraction unit 38 causes the lines 42, 4
Clocks are extracted from 3, 44, and the extracted clocks are sent to the clock selection unit 39 via the extracted clock lines 45, 46, 47. The clock extraction unit 38 sends information about which line can be used for clock extraction to the selection control unit 41 via the clock monitoring line 49. A desired clock is selected by the clock selector 39 based on the selection control signal from the selection controller 41, and the selected clock is output to the selected clock line 48. The selected clock received by the clock generation unit 40 via the selected clock line 48 is converted into a frequency used inside the private branch exchange, output to the internal clock line 51, and supplied to each unit of the private branch exchange.

[0006]

As described above, when there is one system rack and one line interface card, the clock selected by the clock selecting section 39 in the interface card is used as the internal clock of the exchange. It can be used, but if the number of lines accommodated in the switch increases and the system is divided into multiple system racks and multiple line interface cards can be accommodated in one system rack, it is necessary to select a clock. When the management becomes complicated and an abnormality occurs in the line that supplies the clock, it takes a lot of time to switch the line, and efficient operation cannot be performed.

The present invention has been made in order to solve the above-mentioned problems, and even if an abnormality occurs in the line which is supplying the network synchronization clock, the clock management is performed by the three-stage hierarchical clock selection circuit. It is an object of the present invention to provide a network synchronous clock selection circuit for a private branch exchange which can facilitate the above and shorten the line switching time.

[0008]

According to the present invention, the above-mentioned object is a network synchronization clock selection circuit of a building block type private branch exchange which is divided into a plurality of system racks, and a predetermined network synchronization is performed from a plurality of lines. A plurality of line interface means for selecting a line from which the clock can be extracted,
System management means for selecting a line interface means having a line capable of extracting the predetermined network synchronization clock from the plurality of line interface means and controlling outputting the predetermined network synchronization clock to a clock line of a system rack. A frequency that can be used in the private branch exchange by selecting a clock line of the system rack having a line capable of extracting the predetermined network synchronization clock from the clock lines of the plurality of system racks, extracting the predetermined network synchronization clock The network synchronous clock selection circuit of the private branch exchange according to claim 1, further comprising a switching process management means for generating the clock of the above.

According to the present invention, for the above-mentioned object, the line interface means selects a clock extracting unit for extracting a plurality of clocks from the plurality of lines, and selects the predetermined network synchronization clock from the plurality of clocks. 3. A network synchronous clock selection circuit for a private branch exchange according to claim 2, further comprising a clock selection unit and a clock transmission control unit for controlling outputting the predetermined network synchronization clock selected by the clock selection unit to the clock line. Achieved by

According to the present invention, the above-mentioned object is to provide another clock selection section for the exchange processing management means to select a clock line having the predetermined network synchronization clock from the clock lines of the plurality of system racks. 4. A network synchronization clock selection circuit for a private branch exchange according to claim 3, further comprising a clock generation unit for generating a clock having a frequency usable in the private branch exchange from a selected predetermined network synchronization clock.

[0011]

According to the network synchronous clock selection circuit of the private branch exchange of claim 1, the circuit capable of extracting a normal clock from the circuits connected to the respective circuit interface cards in each system rack is hierarchically selected. Select by department,
Since it is output, the switching time of the line can be shortened when the clock of the selected line is abnormal, and management is facilitated by hierarchically managing the clock selection line. The control of the clock selection unit in each line interface card is performed within that card, so that if a line that was supplying the clock fails, a line that can supply the normal clock to the card In some cases, it can switch to that line, which is a very fast switch. If there is no line that can supply a normal clock in the same line interface card, and if there is another line interface card in the same system rack, the system management command to send the clock from that card. As a result, lines can be switched in the same system rack, and switching can be performed faster than selecting a clock from the entire exchange. When an error occurs in all the lines in the system rack, the switching process management unit that manages the entire exchange switches to the clock from the system rack that is sending another normal clock.

According to another aspect of the present invention, there is provided a network synchronization clock selection circuit for a private branch exchange, wherein the clock extraction unit extracts a plurality of clocks from the plurality of lines, and the clock selection unit selects the predetermined network synchronization from the plurality of clocks. Select a clock,
The clock transmission control unit controls the output of the predetermined network synchronization clock selected by the clock selection unit to the clock line. Therefore, it is possible to shorten the line switching time with respect to the abnormal clock of the selected line.

According to another aspect of the present invention, there is provided a network synchronization clock selection circuit for a private branch exchange, wherein the other clock selection unit selects a clock line having the predetermined network synchronization clock from the clock lines of the plurality of system racks and clocks the selected clock line. The generation unit generates a clock having a frequency usable in the private branch exchange from the selected predetermined network synchronization clock. Therefore, if an error occurs in all the lines in the system rack, the clock is switched to the clock from the system rack that is sending another normal clock.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a network synchronous clock selection circuit of a private branch exchange according to claim 1 will be described below with reference to FIG. It is an object of the present embodiment to provide a network synchronous clock selection circuit for a private branch exchange which can facilitate clock management and shorten the line switching time even if an abnormality occurs in the line that has supplied the network synchronous clock. To do.

In this embodiment, a plurality of system racks 1 to n are used.
The system racks 1 to n are connected by communication lines 33 to 37. Since the system racks 1 to n have the same configuration, the system rack 1 will be described as an example.

The system rack 1 includes a plurality of line interface cards 1 as a plurality of line interface means.
1 to 1n, a system management unit 20 as a system management unit for controlling clock transmission from each of the line interface cards 11 to 1n, and an exchange processing management unit 65 as an exchange processing management unit for managing the entire apparatus. is doing. Since the line interface cards 11 to 1n have the same configuration, the line interface card 11 will be described as an example.

The line interface card 11 is connected to a plurality of lines 52, 53, 54 and each line 52, 5
Clock extraction unit 21 for extracting clocks from 3, 54
And the extracted clock lines 55, 5 to the clock extraction unit 21.
6, a clock selection unit 22 for selecting a desired clock based on a selection signal connected thereto, and a clock monitoring line 58 for transmitting information about which line is a clock extractable line. The CPU 23 that selects one of the lines that can be extracted and sends a selection signal to the clock selection line 59 and the clock output selection line 60.
And a clock transmission control unit 24 that outputs the clock selected by the clock selection unit 22 that is received via the selected clock line 61 to the clock line 31.

The system management unit 20 has a CPU 25 for judging which of a plurality of line interface cards the clock is to be output from.
U25 is connected to the CPU 23 of each line interface card by communication lines 26 and 27.

Further, the exchange processing management unit 65 controls the system management unit 20 and the like, a CPU 62, a clock selection unit 63 which selects a network synchronization clock based on a selection signal from the CPU 62, and a selected network synchronization clock. And a clock generator 64 for converting the input clock into a clock having a frequency that can be used by the entire private branch exchange.

Next, the operation of this embodiment will be described.
For ease of explanation, the first system rack 1 will be described as an example.

In the line interface card 11,
A clock is extracted from the lines 52, 53, 54 by the clock extracting unit 21, and the extracted clock is sent to the clock selecting unit 22 via the extracted clock lines 55, 56, 57. At this time, information indicating that the clock cannot be extracted due to disconnection of any one of the lines is the clock extraction unit 21.
It is sent to the CPU 23 via the clock monitoring line 58. A desired clock is selected by the clock selection unit 22 based on a selection signal from the CPU 23, and the selected clock is sent to the clock transmission control unit 24 via the selected clock line 61. At this time, the clock is similarly selected in the other line interface cards 11 to 1n.

In the system management unit 20, the CPU 25 causes the line interface cards 11 to 1n and the communication line 2
Communication is performed via 6, 27, and it is determined whether or not the clock can be extracted from the lines 52, 53, 54 by the line interface cards 11 to 1n. Based on this judgment information, the CPU 25 determines from which line interface card the clock is to be output, and through the communication lines 26 and 27, each line interface card 11
It is instructed whether to output a clock to 1n. For example, when the line interface card 11 is selected, the CPU 23 controls the clock transmission control unit 24 via the clock output selection line 60, and the network synchronization clock line 31 on the data highway bus between the system racks receives the network synchronization clock. Sent out. Note that the network synchronization clocks are similarly sent to the network synchronization clock lines 33 and 34 from the other system racks 2 to n.

In the exchange processing management unit 65 which manages the entire private branch exchange, the network synchronization clocks from the system racks 1 to n are input to the clock selection unit 63, and the CPU 62 checks the clock via the signal line 29. CPU
62 communicates with the CPU 25 of the system management unit 20 in each system rack 1-n via the communication lines 32, 36, 37 to determine whether each system rack 1-n outputs a normal clock. Information is obtained. Based on the information, the CPU 62 controls the clock selection unit 63 via the clock selection control line 28, and the network synchronization clock 30 selected by the clock selection unit 63 is output to the clock generation unit 64. The network synchronization clock selected by the clock generation unit 64 is converted into a frequency used inside the private branch exchange and supplied to each unit of the private branch exchange.

In the line interface card 11,
When the clock extracting unit 21 detects an abnormality in the line signal line 52 for which the clock is selected, the clock extracting unit 21 notifies the CPU 23 of the clock abnormality via the clock monitoring line 58, and the CPU 23 extracts the clock in the card. Normal line line 53 or 54
The clock selection unit 22 is controlled to output the clock extracted from. In this way, if there is another line from which a clock can be extracted in the line interface card in which the line abnormality has occurred, the switching process can be performed in the same card, and the line switching processing time can be shortened.

When the clock from the line interface card 11 is selected and is output to the network synchronization clock line 31, if all the lines in the line interface card 11 are abnormal, the CPU 23 notifies the system management unit of that fact. The CPU 25 in 20 is notified via the communication line 26. An instruction to stop the clock transmission to the CPU 23 in the line interface card 11 is sent from the CPU 25 receiving this information via the communication line 26, and another normal extracted clock can be sent to the line interface card 1n via the communication line 27. Clock transmission is required.

As described above, when the clock can be sent from another line interface card in the same rack, the switching processing can be performed in the same rack.
Processing time is short.

Network synchronization clock 3 from system rack 1
1 is selected by the exchange processing management unit 65, all the line interface cards 1 in the system rack 1 are selected.
When the CPU 25 in the system management unit 20 is notified of the clock abnormality from the communication system 1 to 1n via the communication lines 26 and 27, the CPU 25 communicates the fact to the CPU 62 in the exchange processing management unit 65 that manages the entire private branch exchange. Line 3
Notified via 2. CPU in system management unit 20
The exchange processing management unit 65 notified of the clock error from 25
The CPU 62 controls the clock selection unit 63 via the clock selection control line 28 so as to select the clock of the system racks 2 to n that are sending the normal clock, and the clock is switched.

As described above, when the clocks are switched to clocks from other racks, the processing can be performed in a hierarchical manner, which facilitates the clock management.

[0029]

According to the network synchronous clock selection circuit of the private branch exchange of the first aspect, even if an abnormality occurs in the line supplying the clock, the clock can be extracted into the line interface card in which the line abnormality has occurred. If there is another line, the switching process can be performed within the same card, and the line switching processing time is short. If a line error occurs in all the lines in the line interface card, but the clock can be sent from another line interface card in the same rack, the switching process can be performed in the same rack. The processing time is short. If a line error occurs in all the lines in the rack, the clock is switched to that from another rack. As a result, the processing can be performed hierarchically in three stages, which facilitates clock management.

According to the network synchronous clock selection circuit of the private branch exchange of the second aspect, the switching time of the line can be shortened when the clock abnormality of the selected line occurs.

According to the network synchronous clock selection circuit of the private branch exchange of claim 3, when an abnormality occurs in all the lines in the system rack, the clock from the system rack which is sending other normal clocks. Is switched to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a clock selection circuit of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional clock selection circuit.

[Explanation of symbols]

1-n system rack 11 to 1n line interface card 20 System Management Department 21 Clock extractor 22,63 Clock selection section 23,25,62 CPU 24 Clock transmission control unit 64 clock generator

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Claims (3)

(57) [Claims] 1. A network synchronization clock selection circuit for a building block type private branch exchange divided into a plurality of system racks, and a plurality of line interface means for selecting a line from which a predetermined network synchronization clock can be extracted from a plurality of lines. System management means for selecting a line interface means having a line capable of extracting the predetermined network synchronization clock from the plurality of line interface means, and controlling outputting the predetermined network synchronization clock to a clock line of a system rack And a clock line of the system rack having a line capable of extracting the predetermined network synchronization clock from the clock lines of the plurality of system racks, and extracting the predetermined network synchronization clock, which can be used in the private branch exchange. And a switching management means for generating a clock of frequency. And a network synchronous clock selection circuit for a private branch exchange. 2. The line interface means extracts a plurality of clocks from the plurality of lines, a clock selection unit that selects the predetermined network synchronization clock from the plurality of clocks, and the clock selection unit. 2. The network synchronous clock selection circuit for a private branch exchange according to claim 1, further comprising a clock transmission control unit that controls outputting the predetermined network synchronous clock selected by the above to the clock line. 3. The other exchange selecting means selects another clock line having the predetermined network synchronization clock from the clock lines of the plurality of system racks, and the selected predetermined network synchronization clock. 2. The network synchronous clock selection circuit for a private branch exchange according to claim 1, further comprising a clock generation unit that generates a clock having a frequency that can be used by the private branch exchange.