JP2005260734A - Line quality monitoring system and line quality monitoring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line quality monitoring system for monitoring a quality of a line between transmission apparatuses at all the time. <P>SOLUTION: The line quality monitoring system comprises: a first main signal inspection means that is provided in a first transmission apparatus for inspecting normality of a main signal received from a host device; a transmission means that is provided in the first transmission apparatus for producing a line monitoring signal and transmitting the signal to a second transmission apparatus if no main signal is received from the host device for a predetermined time; a second main signal inspection means that is provided in the second transmission apparatus for inspecting normality of a main signal received from the first transmission apparatus; a line monitoring signal inspection means that is provided in the second transmission apparatus for inspecting normality of the line monitoring signal received from the first transmission apparatus; and an alarm means that is provided in the second transmission apparatus for determining frequency of abnormality detection by the second main signal inspection means and the line monitoring signal inspection means and issuing an alarm if the frequency exceeds a threshold which is held in advance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a line quality monitoring system and a line quality monitoring method for monitoring line quality between transmission apparatuses.

FIG. 5 shows transmission path switching control in a conventional data transmission system.
The data transmission system 20 includes switching devices 1 and 2 provided between transmission devices that transmit and receive data via the active transmission line 11 and the standby transmission line 12, and the active transmission line 11 and the switching devices 1 and 2. There are active media converters 5 and 6 provided between them, and standby media converters 7 and 8 provided between the standby transmission line 12 and the switching devices 1 and 2, respectively.

  In the data transmission system 20 having such a configuration, when a physical failure (transmission path disconnection) indicated by a cross in the figure occurs in the active transmission line 11, the media converters 5 and 6 are connected to the active transmission line 11 side. Link disconnection is detected, and the links on the switching devices 1 and 2 side are forcibly blocked. As a result, since the switching devices 1 and 2 are in an input-off state, the transmission / reception routes are switched from the active system to the standby system by the switching circuits 3 and 4, respectively. As a result, the transmission line switching due to the physical failure of the working transmission line 11 is completed. The transmission line switching from the standby system to the active system is performed in the same manner.

Patent Document 1 discloses a data transmission system without affecting user frame traffic by inserting and transmitting a maintenance management frame including maintenance management information in a guard time (idle time) between user frames. Techniques for performing maintenance and management are disclosed.
JP 2003-18162 A

  However, in the data transmission system 20 described above, deterioration of the line quality in the working transmission line 11 and the standby transmission line 12 is not a factor for switching the transmission line, so the working transmission line 11 (standby transmission line 12). Even if the line quality deteriorates and the data transmission is hindered, the transmission line cannot be switched. For this reason, data transmission is not performed smoothly, and data retransmission processing occurs frequently, increasing the load on the entire network. Further, in the Ethernet (registered trademark) service, user frames are not always transmitted between transmission apparatuses, and therefore, line quality between transmission apparatuses cannot be monitored during a period in which user frames are not transmitted. Accordingly, it is impossible to constantly monitor the line quality between transmission apparatuses.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a line quality monitoring system and a line quality monitoring method capable of constantly monitoring the line quality between transmission apparatuses. Another object of the present invention is to perform transmission line switching when line quality deterioration occurs between transmission apparatuses.

  The line quality monitoring system according to claim 1 transmits a main signal received from a higher-level device to a transmission line, and transmits a main signal received from the first transmission device via the transmission line to a lower-level device. A channel quality monitoring system for monitoring the channel quality with a second transmission device that performs the first main signal test that is provided in the first transmission device and that checks the normality of the main signal received from the host device Means, and a transmission means provided in the first transmission device and generating a line monitoring signal and transmitting to the second transmission device when a main signal is not received from the host device for a predetermined time, and to the second transmission device Provided is a second main signal checking means for checking the normality of the main signal received from the first transmission device, and the normality of the line monitoring signal provided in the second transmission device and received from the first transmission device. Line monitoring signal to inspect An inspection unit is provided in the second transmission device, and the frequency of abnormality detection by the second main signal inspection unit and the line monitoring signal inspection unit is obtained, and an alarm is issued when the frequency exceeds a pre-stored threshold value. And an alarm means for issuing a warning.

The line quality monitoring system according to claim 2 is the line quality monitoring system according to claim 1,
The second main signal inspection means, the line monitoring signal inspection means, and the alarm means provided in the second transmission device corresponding to the transmission lines constituted by an active transmission line and a standby transmission line, The main signal provided to the second transmission device and transmitted to the subordinate device when the alarm means corresponding to the active transmission line issues an alarm, from the main signal received via the active transmission line And switching means for switching to a main signal received via the backup transmission line.

The line quality monitoring system according to claim 3 is the line quality monitoring system according to claim 1, wherein the line monitoring signal is used for signal start information indicating the start of the signal and normality inspection of the line monitoring signal inspection means. It is characterized by error check information and signal end information indicating the end of the signal.
A line quality monitoring system according to a fourth aspect is the line quality monitoring system according to the first aspect, further comprising threshold setting means provided in the second transmission device for arbitrarily setting a threshold for issuing an alarm in the alarm means. It is characterized by that.

  The line quality monitoring method according to claim 5 is a first transmission device that transmits a main signal received from a higher-level device to a transmission line, and a main signal received from the first transmission device via the transmission line to a lower-level device. A channel quality monitoring method for monitoring the channel quality with a second transmission device, wherein the first transmission device checks the normality of the main signal received from the host device and receives the main signal from the host device. When the signal is not received for a predetermined time, a line monitoring signal is generated and transmitted to the second transmission apparatus. On the second transmission apparatus side, the normality of the main signal received from the first transmission apparatus and the line monitoring signal It is characterized in that the normality is checked, the frequency of abnormality detection of the main signal and the line monitoring signal is obtained, and an alarm is issued when the frequency exceeds a pre-stored threshold.

  The line quality monitoring method according to claim 6 is the line quality monitoring method according to claim 5, corresponding to the transmission line constituted by an active transmission line and a standby transmission line on the second transmission device side, Main signal normality check, line monitoring signal normality check and alarm issuance are performed, and when an alarm corresponding to the working transmission line is issued, the main signal to be transmitted to the subordinate device is sent to the working system. The main signal received through the transmission line is switched to the main signal received through the backup transmission line.

  The line quality monitoring method according to claim 7 is the line quality monitoring method according to claim 5, wherein a threshold value for issuing an alarm is arbitrarily set on the second transmission device side.

  In the line quality monitoring system of claim 1 and the line quality monitoring method of claim 5, when a main signal is transmitted between the first and second transmission apparatuses, the normality of the main signal is inspected, and the first and first When the main signal is not transmitted between the two transmission apparatuses, a line monitoring signal is generated and transmitted instead of the main signal, and the normality of the line monitoring signal is checked. For this reason, either the main signal or the line monitoring signal can be always transmitted between the first and second transmission devices, and the normality of the main signal and the normality of the line monitoring signal are respectively inspected. And the line quality between the second transmission devices can be constantly monitored.

  Further, when an alarm is issued, it is easy to estimate the location of the failure by the inspection result of the main signal normality inspection in the first transmission device. That is, when an alarm is issued and no abnormality of the main signal is detected in the first transmission device, it can be determined that the line quality has deteriorated between the first and second transmission devices, and the first transmission When an abnormality of the main signal is detected in the device, it can be determined that there is a problem on the upper device side than the first transmission device.

In the line quality monitoring system according to claim 2 and the line quality monitoring method according to claim 6, since the transmission line can be switched when the line quality deteriorates in the working transmission line, smooth data transmission can be maintained, It is possible to prevent an increase in the load on the entire network due to frequent retransmission processing.
In the line quality monitoring system according to claim 3, since the line monitoring signal is composed of minimum information necessary for monitoring the line quality between the first and second transmission apparatuses, the first transmission apparatus includes the main signal. The line monitoring signal can be transmitted without affecting the transmission operation.

  In the line quality monitoring system according to claim 4 and the line quality monitoring method according to claim 7, since the threshold value for issuing an alarm can be arbitrarily set, it is possible to flexibly respond to various requirements regarding the line quality between the first and second transmission apparatuses. Yes.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the present invention.
A data transmission system to which the present invention is applied includes a transmission apparatus 100 (first transmission apparatus) and a transmission apparatus 200 (first transmission apparatus) that transmit a user frame (main signal) in an Ethernet (registered trademark) frame format via an optical transmission line 300. 2 transmission devices).

The transmission apparatus 100 includes a reception status monitoring unit 102, a timer setting unit 104, a monitoring frame generation unit 106, a packet buffer 108 (first main signal inspection unit and transmission unit), and an EO converter (electro-optic converter) 110. Yes.
The reception status monitoring unit 102 monitors the reception status of a user frame (a frame that originally includes information to be transmitted) transmitted from a higher-level device in the transmission device 100. When receiving the user frame transmitted from the host device, the reception status monitoring unit 102 transmits the user frame to the packet buffer 108. The reception status monitoring unit 102 includes a timer 112 that can be set to a predetermined time by the timer setting unit 104. When the user frame is not received before the timer 112 times out, that is, the user frame is determined in advance. When the time is not received, this is notified to the monitoring frame generation unit 106. The timer 112 is initialized when reception of a user frame is detected or when a timeout occurs.

The monitoring frame generation unit 106 generates a monitoring frame (line monitoring signal) for inspecting the line quality between the transmission apparatuses 100 and 200 when the timeout of the timer 112 is recognized by the notification from the reception state monitoring unit 102. To the packet buffer 108. Details of the monitoring frame generated by the monitoring frame generation unit 106 will be described with reference to FIG.
The packet buffer 108 checks the normality of the user frame received from the host device via the reception status monitoring unit 102. Specifically, the packet buffer 108 has a cyclic redundancy check (CRC) using the FCS (Frame Check Sequence) field prepared in the Ethernet (registered trademark) frame format, and the frame size of the user frame is normal. A test for confirming that the total number of bits of the user frame is an integral multiple of 8 is performed. In the cyclic redundancy check, the packet buffer 108 has a remainder when the polynomial based on the data from the DA (Destination Address) field to the DATA field of the user frame divided by a certain generating polynomial matches the value (CRC value) of the FCS field. Whether or not there is an error in the user frame is determined by checking whether or not to do so.

  If the packet buffer 108 does not detect any abnormal user frame (FCS error, frame size error (short frame and long frame), alignment error), the user frame is transferred to the optical transmission line 300 via the EO converter 110. When a user frame abnormality is detected, the user frame is discarded. Further, when receiving the monitoring frame from the monitoring frame generation unit 106, the packet buffer 108 sends the monitoring frame to the optical transmission line 300 via the EO converter 110.

The transmission apparatus 200 includes an OE converter (photoelectric converter) 202, a packet buffer 204 (second main signal inspection unit), a monitoring frame inspection unit 206 (line monitoring signal inspection unit), an error counter 208 (alarm unit), and threshold setting. The unit 210 (threshold setting means) is included.
The packet buffer 204 receives a frame (user frame or monitoring frame) sent from the transmission apparatus 100 to the optical transmission line 300 via the OE converter 202. When the received frame is a user frame, the packet buffer 204 performs a normality check on the user frame in the same manner as the packet buffer 108 of the transmission apparatus 100. If the packet buffer 108 does not detect any user frame abnormality (FCS error, frame size error, alignment error), the packet buffer 108 sends the user frame to the lower level device. If the user frame abnormality is detected, the packet buffer 108 displays the user frame. Discard. The packet buffer 204 notifies the error counter 208 of the inspection result every time the normality inspection of the user frame is performed. When the received frame is a monitoring frame, the packet buffer 204 sends the monitoring frame to the monitoring frame inspection unit 206.

When the monitoring frame inspection unit 206 receives the monitoring frame from the packet buffer 204, the monitoring frame inspection unit 206 performs a cyclic redundancy check on the monitoring frame. The monitoring frame inspection unit 206 notifies the error counter 208 of the inspection result every time the cyclic redundancy inspection of the monitoring frame is performed.
The error counter 208 increases the counter value in response to the abnormality detection notification from the packet buffer 204 and the abnormality detection notification from the monitoring frame inspection unit 206. The error counter 208 calculates a ratio (error frame rate) of the number of notifications of abnormality detection to the total number of notifications from the packet buffer 204 and the monitoring frame inspection unit 208 in a predetermined cycle, and the calculated error frame rate is calculated by the threshold setting unit 210. Monitoring control for monitoring and controlling the entire network when a set threshold value is exceeded (for example, when the packet buffer 204 receives 10,000 frames within a predetermined time and the number of frames in which an abnormality is detected is greater than 1). An alarm is issued to the center 400.

FIG. 2 shows details of the monitoring frame generated by the monitoring frame generation unit 106 of FIG.
The monitoring frame generated by the monitoring frame generation unit 106 (FIG. 1) includes an 8-bit SSD (Start-of-Stream Delimiter) field (signal start information), a 12-bit DATA field, and a 4-bit FCS field (error check). Information) is composed of a 4-bit ESD (End-of-Stream Delimiter) field (signal end information).

  The SSD field is fixed to “10101010” and indicates the start of the monitoring frame. The DATA field indicates random data used in the cyclic redundancy check by the monitoring frame check unit 206 of the transmission apparatus 200. The FCS field indicates a remainder obtained by dividing a polynomial based on random data in the DATA field by a generator polynomial. The ESD field is fixed to “1010” and indicates the end of the monitoring frame. Thus, by newly defining the monitoring frame, the packet buffer 204 of the transmission apparatus 200 can easily identify the user frame and the monitoring frame. In addition, the monitoring frame inspection unit 206 of the transmission apparatus 200 checks whether the remainder when the polynomial based on the DATA field of the monitoring frame is divided by a generator polynomial matches the value of the FCS field. Determine whether there is a frame error.

FIG. 3 shows an overview of the monitoring frame transmission operation in the transmission apparatus 100 of FIG.
The packet buffer 108 transmits the monitoring frame to the optical transmission line 300 when the monitoring frame is received, that is, when the reception status monitoring unit 102 does not detect reception of the user frame for a predetermined time T. The predetermined time T is set sufficiently smaller than the idle time between user frames, that is, the interframe gap IFG (minimum value: 12 bytes). Since the monitoring frame is composed of 28 bits, the packet buffer 108 can send the monitoring frame to the optical transmission line 300 without affecting the traffic of the user frame.

  In the data transmission system configured as described above, when a user frame is transmitted between the transmission apparatuses 100 and 200, the normality of the user frame is checked, and when the user frame is not transmitted between the transmission apparatuses 100 and 200, A monitoring frame is generated and transmitted instead of the user frame, and the normality of the monitoring frame is checked. Therefore, either the user frame or the monitoring frame is always transmitted between the transmission apparatuses 100 and 200, and the line quality between the transmission apparatuses 100 and 200 is checked by checking the normality of the user frame and the normality of the monitoring frame, respectively. Is constantly monitored.

As described above, in the first embodiment, either the user frame or the monitoring frame can be constantly transmitted between the transmission apparatuses 100 and 200, and by checking the normality of the user frame and the normality of the monitoring frame, respectively. The line quality between the transmission apparatuses 100 and 200 can be constantly monitored.
Further, when an alarm is issued by the error counter 208 of the transmission apparatus 200, the location where a failure has occurred can be easily estimated from the inspection result of the user frame in the packet buffer 108 of the transmission apparatus 100. That is, when an alarm is issued by the error counter 208, if no abnormality of the user frame is detected by the packet buffer 108, it can be determined that the line quality has deteriorated between the transmission apparatuses 100 and 200, and the packet buffer When an abnormality of the user frame is detected by 108, it can be determined that there is a problem on the higher-level device side than the transmission device 100.

  Furthermore, since the monitoring frame is composed of the minimum necessary fields (SSD, DATA, FCS, ESD) for monitoring the line quality between the transmission apparatuses 100 and 200, it does not affect the traffic of the user frame. A monitoring frame can be transmitted. Further, since the threshold value for issuing an alarm can be changed by the threshold setting unit of the transmission apparatus 200, it is possible to flexibly cope with various requests for the line quality between the transmission apparatuses 100 and 200.

FIG. 4 shows a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the element same as the element demonstrated in 1st Embodiment, and detailed description is abbreviate | omitted.
A data transmission system to which the present invention is applied is a transmission apparatus 100a that transmits a user frame (main signal) in an Ethernet (registered trademark) frame format via an active transmission line 302 and a standby transmission line 304 (optical transmission line). (First transmission device) and transmission device 200a (second transmission device).

The transmission apparatus 100a is configured by adding an EO converter 114 to the transmission apparatus 100 (FIG. 1) of the first embodiment. The packet buffer 108 sends the user frame and the monitoring frame to the active transmission line 302 via the EO converter 110, and sends the same user frame and the monitoring frame to the standby transmission line 304 via the EO converter 114. To do.
The transmission apparatus 200 a includes interface units 212 and 214, a switching circuit 216, and a switching control unit 218 connected to the active transmission line 302 and the standby transmission line 304, respectively. The interface units 212 and 214 include the EO converter 202, the packet buffer 204, the monitoring frame inspection unit 206, the error counter 208, and the threshold setting unit 210 in the first embodiment (FIG. 1), respectively.

  The switching circuit 216 receives a user frame sent from the interface unit 212 and a user frame sent from the interface unit 214. In response to the switching request from the switching control unit, the switching circuit 216 transmits a user frame to be transmitted to the lower-level device from a user frame transmitted from the interface unit 212 (214) to a user transmitted from the interface unit 214 (212). Switch to frame. The switching control unit 218 issues a switching request to the switching circuit 216 in response to issuing an alarm from the interface units 212 and 214. Further, the switching control unit 218 notifies the monitoring control center 400 that the line quality has deteriorated in the active transmission line 302 (standby transmission line 304) in response to the alarm issued by the interface unit 212 (214). To do.

As described above, also in the second embodiment, the same effect as in the first embodiment can be obtained. Further, since transmission line switching can be performed when line quality degradation occurs in the active transmission line 302 (standby transmission line 304), smooth data transmission can be maintained, and data re-transmission processing occurs frequently, resulting in the entire network. Can be prevented from increasing.
In the above-described embodiment, an example in which the present invention is applied to a data transmission system using light as a communication medium has been described. However, the present invention is not limited to such an embodiment. For example, the present invention may be applied to a data transmission system using electricity as a communication medium. In this case, the EO converter and the OE converter in the transmission apparatus are not necessary.

  As mentioned above, although this invention was demonstrated in detail, the above-mentioned embodiment and its modification are only examples of this invention, and this invention is not limited to these. Obviously, modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows the 1st Embodiment of this invention. It is explanatory drawing which shows the detail of a monitoring frame. It is explanatory drawing which shows the outline | summary of the transmission operation | movement of a monitoring frame. It is a block diagram which shows the 2nd Embodiment of this invention. It is explanatory drawing which shows the transmission-line switching control in the conventional data transmission system.

Explanation of symbols

100, 100a Transmission device 102 Reception status monitoring unit 104 Timer setting unit 106 Monitoring frame generation unit 108 Packet buffer 110, 114 EO converter 112 Timer 200, 200a Transmission device 202 OE converter 204 Packet buffer 206 Monitoring frame inspection unit 208 Error counter 210 Threshold setting units 212 and 214 Interface unit 216 Switching circuit 218 Switching control unit 300 Optical transmission line 302 Active transmission line 304 Backup transmission line 400 Monitoring control center

Claims (7)

A line between the first transmission device that transmits the main signal received from the higher-level device to the transmission path and the second transmission device that transmits the main signal received from the first transmission device via the transmission path to the lower-level device. A line quality monitoring system for monitoring quality,
A first main signal inspection means provided in the first transmission device for inspecting normality of a main signal received from the host device;
A transmission means provided in the first transmission device and configured to generate a line monitoring signal and transmit it to the second transmission device when a main signal is not received from the host device for a predetermined time;
Second main signal inspection means provided in the second transmission device for inspecting normality of the main signal received from the first transmission device;
Line monitoring signal inspection means provided in the second transmission device, for checking the normality of the line monitoring signal received from the first transmission device;
An alarm that is provided in the second transmission device, obtains an abnormality detection frequency by the second main signal inspection means and the line monitoring signal inspection means, and issues an alarm when the frequency exceeds a pre-stored threshold value A line quality monitoring system. In the line quality monitoring system according to claim 1,
The second main signal inspection means, the line monitoring signal inspection means, and the alarm means provided in the second transmission device corresponding to the transmission lines constituted by an active transmission line and a standby transmission line,
The main signal provided to the second transmission device and transmitted to the subordinate device when the alarm means corresponding to the active transmission line issues an alarm, from the main signal received via the active transmission line And a switching means for switching to a main signal received via the backup transmission line. In the line quality monitoring system according to claim 1,
The line monitoring signal is composed of signal start information indicating the start of a signal, error check information used for normality check of the line monitor signal checking means, and signal end information indicating the end of the signal. Line quality monitoring system. In the line quality monitoring system according to claim 1,
A line quality monitoring system comprising threshold setting means provided in the second transmission device for arbitrarily setting a threshold for issuing an alarm in the alarm means. A line between the first transmission device that transmits the main signal received from the higher-level device to the transmission path and the second transmission device that transmits the main signal received from the first transmission device via the transmission path to the lower-level device. A line quality monitoring method for monitoring quality,
On the first transmission device side,
Check the normality of the main signal received from the host device,
If the main signal is not received from the host device for a predetermined time, a line monitoring signal is generated and transmitted to the second transmission device,
On the second transmission device side,
Check the normality of the main signal received from the first transmission device and the normality of the line monitoring signal,
A line quality monitoring method characterized in that an abnormality detection frequency of a main signal and a line monitoring signal is obtained, and an alarm is issued when the frequency exceeds a pre-stored threshold value. The line quality monitoring method according to claim 5, wherein
On the second transmission device side,
Corresponding to the transmission line composed of the active transmission line and the standby transmission line, the main signal normality inspection, the line monitoring signal normality inspection and the warning issuance are performed, respectively.
The main signal received via the backup transmission line from the main signal received via the working transmission line when the alarm corresponding to the working transmission line is issued A line quality monitoring method characterized by switching to The line quality monitoring method according to claim 5, wherein
A line quality monitoring method, wherein a threshold value for issuing an alarm is arbitrarily set on the second transmission device side.

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