JPH02170655A - Common signal line switching system - Google Patents

Abstract

PURPOSE:To maintain a signal transmitting function and to efficiently use signal terminal equipment by switching the connection to one of plural auxiliary common signal lines in an idle condition when a signal link cannot transmit the signal due to a fault or a maintenance work, and forming the new signal link. CONSTITUTION:The plural auxiliary common signal lines are provided in a switching part 10 of signal terminal equipment 12, when the common signal line part in a signal link 11 cannot be used due to the fault or maintenance work, a signal link control part 13 outputs unusable signal link information to a common signal line state control means 17. The common signal line state control means 17 discriminates the usable auxiliary common signal line depending on the state of a common signal line terminal 16b, selects one of the plural auxiliary common signal lines, outputs it to a switch control part 14 together with the information of the signal terminal equipment, prepares a path 102 between the signal terminal equipment 12 and the auxiliary common signal terminal 16b, and forms the new signal link.

Description

[Detailed Description of the Invention] [Summary] A signal terminal device that transmits and receives signals using a common line signaling method;
Regarding the common signal line switching method of an exchange in which a signal link is configured by a common signal line equipped with a common signal line terminal and a path of a switch unit that connects the signal terminal device and the common signal line terminal, the common signal line portion is used. Common signal line switching enables efficient use of signal terminal equipment by forming a new signal link without using other operating signal links if the signal terminal equipment is normal The purpose is to provide a common signal line terminal that connects to multiple spare common signal lines, and when the signal link in use becomes unavailable, a detection output is generated from the signal terminal device, and the signal link control unit activates the common signal line status management means for selecting a spare common signal line in response to the detection output, and when the switch control section of the exchange receives the selection result of the spare common signal line from the common signal line status management means. A path is configured to connect the signal terminal device and the selected spare common signal line terminal.

[Industrial Field of Application] The present invention relates to a signal terminal device that transmits and receives signals using a common line signaling method, a common signal line having a common signal line terminal, and a switch unit that connects the signal terminal device and the common signal line terminal. This invention relates to a common signal line switching system for an exchange that forms a signal link with a path.

In recent years, a system has been used in exchange networks in which signals for connection control are transmitted and received through a common signal line separate from a call signal line, and is known as a common line signal system.

Switches using this system usually have multiple sets of signal links (consisting of a signal terminal device and a common signal line connected to it) for opposing stations, but these links may be interrupted due to failures or maintenance work. If even one link becomes unusable, the load on the remaining signal links will increase, causing delays in signal transmission and reception, and reduced signal reliability, so it is best to avoid this situation as much as possible. desired.

[Conventional technology] A configuration diagram of a conventional example is shown in FIG.

In the figure, 603 and 60b are signal links, 61a and 61b are signal terminal devices, 62 is a switch section of an exchange, and 63a and 63
b is a common signal line terminal, 64 is a switch control section, and 65 is a central control section.

In the configuration of the conventional example, the switch section 62 is provided with a call signal terminal and an output terminal, although not shown, and switching is performed by the switch section.

The common signal line is connected from the common signal line terminal to another exchange (or relay station of the common signal line), not shown, and transmits signals for connection control, and the common signal line includes the signal terminal device 61a and the common signal line terminal 63a. One signal link is formed by the line and the fixed path 620 of the switch section 62 that connects the two.

In FIG. 6, another signal link is provided by a common signal line including a signal terminal device 6 lb, a fixed path 621 of the switch section, and a common signal line terminal 63b. Note that this exchange may not only be a space division type exchange, but also a digital time division type exchange, and in the latter case, the common signal line uses a specific channel allocated in advance.

In the configuration of this conventional example, if the common signal line connected to the common signal line terminal 63a in one signal link 60a becomes unusable due to a failure or maintenance work, that signal link becomes unusable.

[Problems to be Solved by the Invention] According to the configuration of the conventional example described above, the signal terminal device constituting the signal link and the common signal line connected thereto are fixed, and the common signal line portion becomes unusable. In this case, even if the terminal device A and R can operate normally, that signal link becomes unusable, and another signal link that can be used as a signal link (in the case of Fig. 6, the signal link 60
We have adopted a method using b). However, in addition to the original signal transmission and reception, other signal links have to transmit and receive signals that should be handled by another signal link, which increases the load, causing delays in signal transmission and reception and a decrease in signal reliability. It was causing problems.

Even if the common signal line portion becomes unusable, if the signal terminal device is normal, a new signal link is formed without using other operating signal links, and the signal terminal device is efficiently operated. The purpose is to provide a common signal line switching scheme that can be used.

[Means to solve the problem] FIG. 1 is a diagram showing the basic configuration of the present invention.

In FIG. 1, 10 is a switch section, 11 is a signal link, 12 is a signal terminal device, 13 is a signal link control section, 14 is a switch control section, 15a, b are call signal line terminals, 16a, b are common signal line terminals , 17 is a common signal line state management means.

The present invention provides a plurality of spare common signal lines, and when the currently connected common signal line becomes unusable,
Select one of the available spare common signal lines,
By switching the connection to the signal terminal device and forming a new signal link, the signal transmission function is restored and the signal terminal device is used efficiently.

[Function] The signal terminal device 12 in FIG.
1 is connected to the common signal line terminal 16a to form a signal link 11. This switch section 10 is provided with a plurality of spare common signal lines, and in FIG. 1, one common signal line terminal 16 is representative of the terminals connected to the spare common signal lines.
b is shown.

When the common signal line portion (on the trunk line including the common signal line terminal 16a) of the signal link 11 becomes unusable due to a failure or maintenance work, the signal terminal device 12 detects this and informs the signal link control unit 13 that it is unusable. Notification will be given. In response, the signal link control section 13 outputs information on the signal link that has become unusable to the common signal line state management means 17.

The common signal line state management means 17 identifies a usable spare common signal line by the state of the common signal line terminal 16b, selects one from among the plurality of spare common signal lines, and controls the signal terminal device. It is output to the switch control unit 14 along with the information. Upon receiving the information, the switch control section 14 controls the switch section 10, creates a bus 102 between the signal terminal device 12 and the spare common signal line terminal 16b, and forms a new signal link. Therefore, even if the common signal line portion becomes unusable, when the signal terminal device can operate normally, the signal transmission function of the signal terminal device can be utilized as long as there is a vacant common signal line.

[Example] Fig. 2 is a system configuration diagram of a digital exchange in which the present invention is implemented, Fig. 3 is an explanatory diagram of the relationship between circuits and lines housed in a digital switch module, and Fig. 4 is a processing flow diagram of the embodiment. , FIG. 5 is an explanatory diagram of a method for detecting a fault in a common signal line.

In FIG. 2, 20a and 20b are signal terminal devices, 21 is a digital switch module (indicated by DSM) for time-division exchange of digital call signals and common signal line signals, and 22 is a call processing and signal terminal. Call processor (indicated by CPR) that processes the device, 2
3 represents a digital terminal trunk card (indicated by DT) equipped with a circuit for PCM multiplexing channel signals input from a large number of terminals and outputting the same to the link LINK. In this example, the DSM has a two-sided configuration, one for switching in the transmission direction and the other for switching in the reception direction.

Moreover, the signal terminal devices 20a and 20b each have an error (
A common signal line device that performs functions such as adding check codes for signal transfer, detecting transmission errors, confirming transmission, and controlling retransmission (represented by CSE).
el signaling equipment) and a common signal line equipment interface (denoted as CSEI: C
oa+1lon channel signaling
The call processor 22 consists of a central controller (indicated by CC: Central Controller) and a channel control device (indicated by CHC: Channel Co).
controller), and performs bidirectional communication via a common signal line.

FIG. 3 shows an explanatory diagram of the relationship between circuits and lines housed in the digital switch module.

The DSM (digital switch module) 32 includes a C5E30 (common signal line device) that constitutes a signal terminal device.
In addition to the terminals connected to CSE I.31 (C3E interface), subscriber line trunks (indicated by SLT: 5
1ine trunk), an outgoing trunk (indicated by OCT), and an incoming trunk (indicated by ICT). On the other side of the DSM 32 are multiple DTs (digital terminal trunk cards) 33 to 3.
Each channel terminal is provided to input to PC 5, and each DT is connected to PC
A multiplexed signal having an M24 channel frame structure is output.

In this configuration, C5E30 connects DT33 from the terminal of channel CH3 via a specific bus (hot line) in DSM32.
The frame 330 is outputted from the frame 330, and the current signal is transferred to the time slot of the channel CH3.

Further, DT34 and DT35 are each provided with a spare signal channel, and DT34 has channel CH22,
Channel CHIO is assigned to channel 35. When the currently used channel is unavailable, one of these spare signal channels is selected to form a signal frame, but normally no bus is set in the DSM.

Next, the switching processing flow of the embodiment shown in FIG. 4 will be explained.

This switching process is executed in the CPR (call processor) in the configuration shown in FIG.
It is executed by exchanging signals with other devices such as E and C3EI) and DSM. A in FIG. 4 is a process in the exchange shown in FIGS. 2 and 3 (hereinafter referred to as the local exchange), and B in FIG.
This is a process executed in the other station.

At A, when a failure occurs in the common signal line for the currently activated signal link of the own station and a failure detection notification issued from the signal terminal device is received, a signal line switching check is performed (steps 401 and 402). . This check is to check whether switching of the common signal line is permitted at this point, and if it is permitted, the bus of the common signal line that has been used so far is disconnected (step 403). This disconnection is to disconnect the bus between C3E I and the current signal channel terminal (see Figure 3). Next, it is determined whether there is a spare data link (a common signal line and a spare signal channel that can be used) (steps 404, 4).
05). At this time, if it is found that there is a spare data link, it performs an operation to capture the spare data link, determines whether the capture has been performed, and if it is captured, displays information on the captured spare data link. Other signal links (
(usually provided with multiple common signal line data links) to other stations. Subsequently, when a switching operation is performed, a state of waiting for switching completion is entered (step 410).

On the other hand, other stations are also receiving (or transmitting) signals through the same common signal line, and as shown in FIG. ~41
Processing similar to that in step 0 is performed, and in step 429 the process waits for the completion of switching. The other station then receives the switching notification sent from the local station via another signal link. The switching notification includes information on the backup data link selected by the local station.

At this point, the other stations check whether the switching is prioritized (steps 431 and 432). This check is to determine which of the spare data link that was already acquired in step 426 and switched by the other station and the spare data link notified from the local station has priority. In this example, since it is set in advance that other stations have no priority, the captured data link is released, the notified spare data link is captured (step 434), the bus connection is established, and the switching is completed. (step 43).
6). Thereafter, signals are sent and received using the switched spare data link.

When the local station receives a switching notification from another station (step 410), it performs a switching priority check, but if it is determined that the local station has priority, it enters a state of waiting for switching completion (step 413). , 414). In this state, when a notification of completion of switching is received from another station via another signal link, the signal terminal equipment (C3E, C
Step 415) executes control to form a bus connecting the terminal of 3EI) and the terminal of the backup data link, and thereby starts transmitting and receiving signals using the new signal link, resulting in an active state.

Next, a failure detection operation sequence by the signal terminal device shown in FIG. 5 will be explained.

The signal terminal equipment transmits 22 signal bits in response to a message transmission request from the upper layer (upper layer of the protocol) and transfers the received signal unit to the upper layer, but when there is no transmission request from the upper layer. But signal unit (fill in signal unit 7): Fill In Signal tln
The normality of the common signal line is confirmed. On signals transmitted and received between signal terminal devices, there is always a forward sequence number (displayed as FSN: Forward 5eque) as information indicating the order of the signal.
nce Number) and backward sequence number (BS
Display with N: Backward 5equence N
umber) and sends it. The FSN indicates the sequence number of the transmitted signal unit, and the BSN is returned as an acknowledgment and indicates the sequence number of the received signal unit.Signal transmission and reception proceed while mutually confirming signal transmission and reception.

The signal unit also has forward status display bits 1-(FIB display 2) as status display bits.
dicator bit) and reverse direction status display bit (B
Display in IB: Backward Indicator
Btr) is assigned and used when a signal is lost, BIB requests retransmission by inverting the bit, and FIB
B indicates retransmission due to bit inversion (inversion of the previously sent FIB).

The sequence in FIG. 5 shows a case where the signal unit transmitted from the A station is received at the B station, and the reception result is responded to the A station.

Therefore, the FIB and FSN are used for transmission from the A station, and the BIB and BSN are used for response transmission from the B station. Note that for transmission of a signal unit in the opposite direction, that is, from station B to station A, station A transmits BIB and BSN, and station B uses FIB and FSN.

If the signal unit sent from A station is not received due to a failure (signal loss) when FSN = 4 in ■, A
The signal unit with FSN = 5 transmitted from the station has a signal sequence error (signal 5 sequence NG) at station B.
Then, 1 is added to an NG counter (not shown) provided in the signal terminal device. Thereafter, when station B responds by setting BIB=0, station A retransmits from FSN=4 to FIB=0.

In this way, in this example, whenever signal loss occurs for the signal units (■) and (2), 1 is added to the NG counter each time.

This NG counter is cleared at regular intervals, but if a loss of signal is detected a certain number of times (for example, 64 times) or more during this period, the signal terminal equipment determines that the quality of the common signal line is poor (failure), and the central Notify the control device that there is a signal link failure.

Failures in the common signal line can be detected in this way, but if the common signal line becomes unusable due to maintenance work, the switching process can be input by giving instructions from the keyboard on the console. can do.

[Effects of the Invention] According to the present invention, when a certain signal link becomes unable to transmit signals due to a fault in the common signal line or maintenance work, a vacant common communication line is selected from a plurality of prepared spare common signal lines. By switching to the line and forming a new signal link, it is possible to maintain the signal transmission function and use the signal terminal equipment efficiently.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle configuration of the present invention, Fig. 2 is a system block diagram of a digital exchange in which the invention is implemented, Fig. 3 is an explanatory diagram of the relationship between circuits and lines housed in a digital switch module, and Fig. 4 5 is a process flow diagram of the embodiment, FIG. 5 is an explanatory diagram of a common signal line failure detection method, and FIG. 6 is a configuration diagram of a conventional example. In FIG. 1, 10: Switch section 11: Signal link 12: Signal terminal device 13: Signal link control section 14: Switch control section 15a, b: Call signal line terminals 16a, b: Common signal line terminal 17: Common signal line Condition management means calyx (4'EF (--J tea area)

Claims (1)

[Claims] A signal terminal device (1
2), a common signal line with a common signal line terminal (16a), and a common signal line with the signal terminal device (12) and the common signal line terminal (16a).
In the common signal line switching system of the exchange, in which the path (101) of the switch unit (10) connecting the switch unit (10) and the signal link (11) are configured, the common signal line terminal (1) connected to a plurality of spare common signal lines is
6b) is provided, and when the signal link (11) in use becomes unavailable, the signal terminal device (12) generates a detection output, and the signal link control unit (13) responds to the detection output to send a standby common communication When the switch control unit (14) of the exchange receives the selection result of the spare common signal line from the common signal line status management unit (17), A common signal line switching method characterized by forming a path (102) connecting a device (12) and a selected spare common signal line terminal (16b).