JPH09130304A - Line switchng system for data communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the inexpensive switching system for means, not losing data in switching a line. SOLUTION: The error detection signal imparting part 102 of an equipment 1 imparts a counted value to the data signals of an information processing part 101 and outputs them. An active transmission part 103 and a standby transmission part 113 perform output to the equipment 1 as an outgoing standby line. The equipment 2 receives an outgoing active line in an active reception part 221 and an active error detection part 222 outputs active error presence/ absence signals. In a standby error detection part 232, standby error presence/ absence signals are outputted. A switching part 223 switches active data signals and standby data signals, based on the output changeover control signals of the information processing part 201. In the case of receiving a changeover request from the equipment 2, the information processing part 101 prolongs the time of an idle state until information signals to be transmitted next. The information processing part 201 of the equipment 2 also behaves similarly in the case of receiving the changeover request.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching system for data communication in which a line is switched between a working line and a protection line to relieve a data line failure.

[0002]

2. Description of the Related Art In a conventional data signal line switching system,
Line switching was performed regardless of the content of the data signal being transmitted.

An example of a conventional data signal line switching system is disclosed in Japanese Patent Application Laid-Open No. 2-90773.

In the above-mentioned publication, as shown in the block diagram of FIG. 6, when a failure occurs in the dedicated line 11 for data communication, a message is transmitted from the calling station 13 to the called station 14 and transmitted to the called station 14. When the 14 returns a response, the identification message registered in the identification message holding unit 15 is transmitted by the message transmission unit 16. In the called station 14, after receiving the identification message in the message receiving unit 17, the identification message determining unit 18 determines the validity of the identification message. According to the result, the line switching is performed.

[0005] As described above, when switching is performed, a system is used in which switching is performed as long as the line involved in switching is confirmed.

[0006]

In the above-mentioned conventional configuration, when a failure occurs in the line and an error occurs in the data being transmitted, the line is switched even when the content of the data being transmitted is in the middle of a message. For example, even if a control signal or information signal is being transmitted, switching occurs and even if the data on the protection line that is transmitting normal data is received, a normal protection line is transmitted in the middle of the telegram. As for the data, at least one telegram was wasted.

In order to solve the above problem, the present invention does not perform line switching immediately when it is determined that line switching is necessary, for example, when an error is detected in the working line in the slave device and the number of errors is counted and it is determined that line switching is necessary. In this case, the parent device is informed of the intention of line switching and the idle state is lengthened, so that the contents of the data signal being transmitted are not wasted, and the line switching is performed during the idle state without transmitting the control signal or the information signal. By doing so, it is an object to provide a circuit switching configuration with less waste and high reliability.

[0008]

According to the line switching method of the data communication of the present invention, two opposing devices for transmitting and receiving a data signal each transmit on a transmitting line through a working line and a protection line,
In a line switching method of data communication in which a receiving side detects an error in the received data of the working line and the protection line and switches to a normal line side, one of the two devices detects the predetermined number or more of the errors. If it is determined that line switching is necessary, the device sends a line switching request to the other device, and after confirming that the idle state has continued for a predetermined time M after receiving the received data, means for switching the line. And the other device sets the idle state between transmission data to a predetermined time N during normal operation, and further receives the line switching request of the one device and further sets the idle state time between the transmission data to the predetermined time N. There is a means to lengthen.

According to the present invention, when a fault occurs in a line and an error occurs in a received data signal, a line switching request is transmitted to the transmitting side, the idle state is continued for a fixed time, and the idle state is set for a predetermined time. Since line switching is performed during the idle state after confirming that the line switching is performed, that is, line switching is not performed during transmission of a control signal or an information signal, etc. Moreover, line switching can be performed without hits.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a line switching system according to one embodiment of the present invention.

[0011] In the figure, there is a bidirectional connection between the uplink and the downlink, and the configurations of the uplink and the downlink are the same. Here, the communication devices 1 and 2 have the same configuration, and exchange data signals such that the device 2 returns a response signal to control or information signals from the device 1.

First, a control signal, an information signal, and the like (hereinafter, referred to as a control signal) are output from the information processing section 101 of the device 1 as a transmission data signal S1. The transmission data signal S1 is not an output of a control signal or the like having different contents continuously, but is in an idle state in which no data is output for a predetermined time N after one control signal is output.

The error detection signal adding section 102 receives the transmission data signal S1, counts the error for error detection, adds the counted value to the transmission data signal, and outputs it as a data signal S2.

The working transmitter 103 receives the data signal S2 and outputs it on the downstream working line S5.

[0015] The spare transmission section 113 receives the data signal S2 and sends it out on the downlink spare line S4.

The working receiver 221 of the device 2 receives the data signal S2 on the downlink working line S5 and receives the working reception signal S2.
Send 1

The working error detection section 222 receives the working reception signal S21, performs error detection, counts the number of errors, and if the number of errors exceeds a preset threshold, exceeds the number of errors.
It outputs a working error presence / absence signal S23 for notifying that there is an error in the working line and further a working data signal S27.

As with the working line, the protection line 231 of the device 2 receives the signal of the downlink protection line S4 and outputs a protection reception signal S22 in the same manner as the working line.

The spare error detector 232 has the same function as the working error detector 222, receives the spare received signal S22, detects an error, and outputs a spare data signal S26 and a spare error presence / absence signal S24 as an error detection count result. I do.

In the switching section 223, the working data signal S27
, A spare data signal S26 and a switching control signal S27, and performs line switching based on the switching control signal S25 to output a reception data signal S28.

The information processing unit 201 of the device 2 receives the received data signal S28 and performs various processes. Information processing unit 20
As the contents of the transmission data signal S29 output from the communication device 1, in addition to the response to the control contents from the information processing unit 101 of the device 1, in particular, the working error existence signal S23 and the spare error existence signal S24 are inputted, The presence or absence of an error is monitored, and as a result of the monitoring, for example, if an error occurs in the downlink working line and the downlink protection line has no error, a line switching request signal is output as the transmission data signal S29. Further, when a line switching request is made, the idle state continues for a predetermined time M (M is a time shorter than L, which will be described later) after receiving the erroneous reception data signal S28. Switch control signal S2
5 is output.

The error detection signal adding section 202 receives the transmission data signal S29, counts it for error detection, and adds the counted value to the transmission data signal S29 to add the data signal S30.
Output as

In the active transmission unit 203, the data signal S30
And sends it out on the upstream working line S31.

In the preliminary transmission section 213, the data signal S30
And sends it out on the upstream protection line S32.

The circuit configuration on the upstream side of the device 1 is as follows.
It has the same configuration as the downstream side of the device 2.

The information processing unit 101 of the apparatus 1 performs various processes on the input received data signal S35. In particular, when the content is a line switching request, a predetermined time L (L is longer than N) ) Only idle continuously. Thereafter, the information signal to be transmitted next is transmitted.
Even the information processing unit 101 of the device 1 is the information processing unit 2 of the device 2.
As in the case of 01, the working error presence / absence signal S34 and the protection error presence / absence signal S33 are input, and the presence or absence of a line error is monitored. In this case, the idle control time until the next transmission data signal S1 to be transmitted is output is extended, and the switching control signal S36 is output.

Therefore, in the downlink, after the line switching request is output, the line is switched when the idle state continues for a predetermined time M (idle state), and the line is switched during the idle state in the uplink. Since line switching is not performed during transmission of a message such as a control signal, line switching can be performed without hitting while maintaining the line quality without wasting the message.

FIG. 2 is an example of a transmission / reception sequence of a transmission / reception signal between the device 1 and the device 2.

The device 1 outputs a control signal 1 and the like. Device 2
Outputs the response signal 1 after receiving the control signal 1 and the like.

After receiving the response signal 1, the device 1 enters an idle state for a certain period of time.

After the device 1 has been idle for a certain period of time,
It outputs a control signal 2 and the like.

The device 2 outputs a response signal 2 after receiving the control signal 2 and the like.

That is, a control signal or the like is not continuously transmitted from the device 1 to the device 2, and an idle state exists between the control signal and the next control signal.

In the above description, the case where a failure has occurred in the downstream working line has been described, but the same operation is performed in the upstream line.

FIG. 3 shows an example of the format of data transmitted and received between the device 1 and the device 2.

The control signal / response signal includes an address, data and an error detection code between a start flag and an end flag. The control signal and the response signal are idle for a time N.

FIG. 4 shows an example of a transmission / reception sequence of a transmission / reception signal between the device 1 and the device 2 when a failure occurs in the working line.

When an error is detected in the control signal 1 of the working line output from the device 1, a response signal 1 requesting line switching is output from the device 2.

The device 1 continues the normal idle state for a predetermined time because it is a request for switching the line by looking at the content of the response signal 1 from the device 2.

The device 2 counts the idle state time, confirms that the idle state has continued for a predetermined time, and issues a line switching instruction to the switching control signal S2.
5, output to S36.

The device 1 outputs a control signal or the like 2 after continuing the idle state for a predetermined time. The device 2 uses a control signal or the like 2 received on the protection line.

FIG. 5 is an example of a timing chart for performing line switching when a failure occurs on a working line for transmitting and receiving signals between the device 1 and the device 2.

When an error is detected in the control signal or the like 1 of the downstream working line, a line switching request is transmitted in response 1 using the upstream working line.

The downlink output from the apparatus 1 is in an idle state continuously for a predetermined time since the downlink request is received.

The device 2 confirms that the idle state of the downlink has continued for a preset time and outputs a line switching instruction with a switching control signal to switch from the working line to the protection line. .

[0046]

As described above, according to the present invention,
In the case of a downlink, an error occurs in the selected line, and when performing line switching, the necessity of line switching is communicated to the sending end station, and the idle state time is extended, and line switching is performed during the extended idle state. By carrying out, in the case of the uplink, the idle switching time is extended and the line switching is performed during the idle state, that is, the line switching is performed during transmission / reception of a valid control signal, concession signal, response signal, or the like. Therefore, there is an effect that line switching can be performed in a hitless manner by minimizing waste of transmission / reception signals.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a line switching system for data communication according to an embodiment of the present invention.

FIG. 2 is a sequence diagram of a line switching system for data communication according to an embodiment of the present invention.

FIG. 3 is a data format diagram of a line switching system for data communication according to an embodiment of the present invention.

FIG. 4 is a sequence diagram of a line switching method for data communication according to an embodiment of the present invention.

FIG. 5 is a timing chart of a line switching method for data communication according to an embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional data communication line switching method.

[Explanation of symbols]

 Reference Signs List 1 device 2 device 11 dedicated line 12 protection line 13 calling station side 14 called station side 15 identification message holding unit 16 message transmission unit 17 message reception unit 18 message judgment unit 19 line switching unit 101 information processing unit 102 error detection signal addition Unit 103 Working transmitting unit 104 Reserve transmitting unit 121 Working receiving unit 122 Working error detecting unit 124 Switching unit 131 Reserve receiving unit 132 Reserve error detecting unit 221 Working receiving unit 222 Working error detecting unit 223 Switching unit 231 Reserve receiving unit 232 Reserve error detecting Unit 201 information processing unit 202 error detection signal assigning unit 203 working transmission unit 204 preliminary transmission unit

Claims (4)

[Claims] An apparatus for transmitting and receiving a data signal transmits and receives data on a working line and a protection line on a transmitting side, respectively.
In a line switching method of data communication in which a receiving side detects an error in received data of the working line and the protection line and switches to a normal line side, one of the two devices detects the error of a predetermined number or more. However, if it is determined that line switching is necessary, the device sends a line switching request to the other device, and after confirming that the idle state has continued for a predetermined time M after receiving the received data, the line switching is performed. The other device, when normal, the idle state between the transmission data is a predetermined time N, in response to a line switching request of the one device, further idle time between the transmission data is the predetermined time N Circuit switching system for data communication, comprising means for making the time longer than the time N. 2. The line switching method for data communication according to claim 1, wherein said predetermined time M is longer than said predetermined time N. 3. The means for making the length of time longer than the predetermined time N, wherein the idle state between transmission data is set to a time L longer than a predetermined time M in response to a line switching request of the one device,
2. The data communication line switching method according to claim 1, wherein when the line switching is necessary, the time is increased by a time required for the line switching. 4. A line switching method of data communication for switching a working line and a protection line between a first device and a second device to remedy a data line failure, the first device and the first device The sending end of the device 2 counts the transmission data signal, adds the count value to the transmission data signal and outputs the data signal, and an error detection code addition unit that inputs the data signal and outputs it as the working line. A working transmission unit, a protection transmission unit that inputs the data signal and outputs it as a protection line, and a reception side of the first device and the second device that receives the working line and outputs a working reception signal. A receiver,
The working reception signal is inputted, error detection is performed, the number of errors in the reception data signal is counted, and if the number of errors exceeds a predetermined first threshold, a working error signal for outputting a working error presence / absence signal and a reception data signal is output. A detection unit, a standby reception unit that receives the standby line and outputs a standby reception signal, and inputs the standby reception signal, performs error detection, counts the number of errors in the received data signal, and sets the number of errors to a predetermined second number. When the threshold value is exceeded, a spare error detection unit that outputs a spare error presence / absence signal and a spare received data signal, and inputs the working data signal, the spare data signal, and the switching control signal, and switches the line based on the switching control signal. A switching unit that switches and outputs one of a working data signal and a protection data signal as a reception data signal, wherein the first device and the second device are configured to receive the input working error signal. And, based on the preliminary error presence / absence signal, when it is determined that line switching is necessary, a line switching request is output as the transmission data signal, and when a line switching request is made, the reception data signal having the error is output. After confirming that the idle state has continued for a predetermined time after the input, the switching control signal is output. After outputting the transmission data signal, the transmission data signal is set to the idle state for a predetermined time N and the next transmission data signal is output. When it is determined that line switching is necessary based on the input working error presence / absence signal and the spare error presence / absence signal based on the input working error presence / absence signal and the spare error presence / absence signal, A line switching method for data communication, comprising: an information processing unit for controlling to output a line switching control signal in which an idle state time is extended by a time relating to line switching.