JP2008227782A - Line duplex ge-pon system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform switch processing with a simple means by connecting a master station device and a slave station device with two communication lines and allowing communication by one line when the other line deteriorates in communication with respect to a line duplex GE-PON (Gigabit Ethernet (R)-Passive Optical Network) system. <P>SOLUTION: A GEPON master station device 1-2 is connected to a backbone via a higher order switch device 1-1, mounts a plurality of interface boards (RIF#1, PIF#2, and so on), and is connected to a plurality of GEPON slave station devices 1-5 on a plurality of subscribers' side with a line used at a normal time and a line used at an abnormal time via an optical fiber catle 103 and a photocoupler 104. When it is detected by the master station device 1-2 or the slave station device 1-5 that the quality of the line used at a normal time deteriorates, the line used is physically switched to the line used at the abnormal time, and a frame signal with a MAC address of a lower order side device of the slave device 1-5 as a transmitter address is transmitted to a higher order switch device 1-1 and to have it learn the MAC address. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dual line GE-PON (Gigabit Ethernet (registered trademark) -Passive Optical Network) system, and in the GE-PON system, it is possible to prevent a PON section communication failure or a non-communication state due to a deterioration in the communication state of the PON section. The present invention relates to a dual line GE-PON system.

  The GE-PON uses an optical fiber cable and a photocoupler to connect a plurality of subscriber-side line terminators (ONU) to one station-side line terminator (OLT). This is a network that enables bidirectional communication at a communication rate in units of gigabits / s between a station side line terminator (OLT) and a subscriber side line terminator (ONU).

  During normal operation of GE-PON, the optical fiber cable deteriorates or an abnormality occurs in the photocoupler etc. in the communication path, and the downstream communication from the station side to the subscriber premises side or from the subscriber side Communication in the upstream direction to the station side may deteriorate. At this time, the signal between the deteriorated station side line terminator (OLT) and the subscriber side line terminator (ONU) is communicated with other subscriber side line terminators (ONUs) in the same GE-PON section. May be adversely affected.

  In order to prevent such a situation from occurring, it is necessary to increase the reliability of the communication line by, for example, duplicating the communication path. However, the duplication of communication paths has various problems depending on the communication method of the higher-level equipment connected to the station-side line terminator (OLT) and the subscriber-side line terminator (ONU). There is a need for a means of implementation that includes avoidance of points.

In the PON system, an invention relating to a communication device that realizes duplexing of a physical route to a subscriber side is described in Patent Document 1 below. The invention described in this document connects at least two subscriber-side line terminators (ONUs) to a station-side line terminator (OLT) and either one of the two subscriber-side line terminators (ONUs). One is selected using a spanning tree protocol, or the two subscriber-side line termination units (ONUs) are connected by a link aggregation protocol.
JP 2004-179723 A

  Due to deterioration of communication media such as optical fiber cables and photocouplers in the PON section, communication failure occurs in the subscriber-side line termination unit (ONU) itself connected to the deteriorated medium. The calculation of dynamic bandwidth allocation (DBA) in the device (OLT) is not normally performed, which may adversely affect other subscriber line terminating devices (ONUs) in the same PON section.

  In the conventional PON system, no bandwidth is given to the subscriber-side line terminator (ONU) connected to the line in which the error is detected in the communication signal, so that the other subscriber-side line terminator (ONU) A measure was taken to prevent adverse effects. However, this means cannot relieve the communication failure of the subscriber-side line terminator (ONU) connected to the deteriorated line.

  In addition, in order to duplicate the communication line between the station side and the subscriber side and connect between them by the spanning tree protocol or the link aggregation protocol, it is necessary to have a processing function unit for executing these complicated protocol processing procedures. Therefore, it is difficult to realize by simple means.

  In the present invention, a master station device and a slave station device are always connected by two communication lines, and even if one line causes communication deterioration, communication can be performed by using the other normally operating line. An object of the present invention is to save communication failures due to degradation of the quality of the line and to realize switching processing thereof with simple means.

  The line duplex GE-PON system according to the present invention is a GE-PON system in which one master station device and a plurality of slave station devices are connected by a communication line using a plurality of optical fiber cables and photocouplers. The slave station apparatus is connected to the master station apparatus through the two communication lines of the normal use line and the abnormal use line, and the normal station apparatus is connected to the master station apparatus through the two communication lines. A normal-time transmission / reception unit connected to the normal-use line and an abnormal-time transmission / reception unit connected to the abnormal-use line, wherein the normal-time transmission / reception unit and the abnormal-time transmission / reception unit are transmitted from the master station device. A system that has a signal reception deterioration detection unit that detects a signal deterioration of a direction signal, and switches a use line based on a signal reception deterioration detection state input from the signal reception deterioration detection unit of the normal transmission / reception unit A system that outputs a selection signal and a common unit that transmits a frame signal having the MAC address of the lower-level device of the own device as a transmission source address to the higher-level switch device of the master station device, and is output from the common unit A transmission / reception system selection switch that outputs a frame signal input from a user interface to either the normal-time transmission / reception unit or the abnormal-time transmission / reception unit according to a selection signal is provided.

  The master station device connected to one slave station device through the two communication lines includes first and second interface boards connected to the normal use line and the abnormal use line, and And the second interface board each have a signal degradation detection unit and a common unit for detecting signal degradation of the uplink signal transmitted from the slave station device, and the signal reception degradation detection input from the signal degradation detection unit Based on the situation, the first and second interface boards are provided with a control board for transmitting a control signal for switching the use line from the normal use line to the abnormal use line to the first and second interface boards. When the common part of the interface board receives a control signal from the control board, it transmits an instruction to switch the used line to the slave station device, and is transmitted from the slave station device. Receiving a frame signal as the source address MAC address of the lower-side device of the child station device characterized by having a configuration for transmitting the frame signal to the upper switch device.

  In addition, when the master station device switches from the normal use line to the abnormal use line, a frame signal having a MAC address of a lower-level device of the slave station device as a transmission destination address is transmitted from the slave use line to the slave station. When the slave station device receives the frame signal from the abnormal use line, the slave station device transmits a frame signal having the transmission destination address of the frame signal as a transmission source address to the master station device. The base station apparatus transmits the frame signal transmitted from the slave station apparatus to the higher order switch apparatus.

  According to the present invention, the master station device and the slave station device are always connected by two lines, and when one line is deteriorated or damaged in communication, the connection is physically switched to the other line. Because the MAC address of the lower-level device of the slave station device connected to the performed line is notified to the higher-level switch device, even if one line causes communication deterioration, it depends on the other normal line Communication is possible and communication failures due to line quality deterioration can be saved, and switching processing thereof can be quickly executed by simple means without executing a processing procedure using a complicated protocol.

  FIG. 1 shows the configuration of a GE-PON duplex system according to the present invention. In the figure, a GEPON master station device 1-2 installed on the station side is connected to a backbone (a large-capacity backbone communication line connecting communication carriers) via a higher-level switch device 1-1 such as a layer 2 switch. A plurality of interface boards (PIF # 1, PIF # 2,...) Having a function of converting an optical signal transmitted and received by an optical fiber cable into an electrical signal is mounted.

  Each interface board (PIF # 1, PIF # 2,...) Of the GEPON master station device 1-2 is connected to a plurality of subscribers via an optical fiber cable 1-3 and a photocoupler 1-4. It is connected to the optical modules (MDL # 1, MDL # 2) in the GEPON slave station device 1-5.

  As shown in FIG. 1, the GEPON slave station device 1-5 includes two optical modules (MDL # 1, MDL # 2) connected to the GEPON master station device 1-2 via two optical fiber cables. One of them, for example, an optical module (MDL # 1) is prepared for a communication line used during normal operation, and the other, for example, an optical module (MDL # 2) is prepared for a communication line used when abnormal.

  When it is recognized that the communication quality of the communication line used during normal operation has deteriorated for some reason and the communication is in an abnormal state, processing is performed to switch the used line to the use line side at the time of abnormality. Remedy from the degraded state. In the GEPON slave station device 1-5, the communication deterioration state is recognized by detecting an error by CRC (Cyclic Redundancy Check) code check of downlink communication data, detecting a packet loss, etc. The device 1-2 recognizes the error by detecting an error by checking the CRC code of the uplink communication data, detecting the state of the handshake signal (OAM frame) from the GEPON slave station device 1-5, or the like.

  These communication deterioration state detections recognize a communication deterioration state causing a communication abnormal state when the number of occurrences of the deterioration state within a predetermined time exceeds a certain threshold value, and switch the use line to the line used in the event of an abnormality. It can be set as the structure which processes.

  Here, the problem when switching from the normal use line to the abnormal use line is the switching of the lower communication line in the upper switch device 1-1 connected to the upper side of the GE-PON. Accordingly, the association (MAC address) between the MAC (Media Access Control) address of the communication device to which the lower communication line is connected and the port number of the upper switch device 1-1 to which the lower communication line is connected. It is how to conduct learning.

  In the upper switch apparatus 1-1, normally, the MAC address connected to the lower communication line device is learned and held, and the unlearned MAC address among the upstream frame signals input to each port is stored. In many cases, a frame signal having a transmission source address is not transmitted to the backbone side because it is an error frame signal.

  Therefore, when the communication deterioration state of the normal line is detected and the line is switched from the normal line to the abnormal line, even if the line state is improved on the GE-PON, the abnormal line is used. Since the association between the line port number and the source MAC address is different from the association that has already been learned and held, it means that an unlearned frame signal has been received, and the higher-level switch 1-1 discards the frame signal. May end up.

  In order to avoid such a situation, when the use line in the GE-PON is switched from the normal use line to the abnormal use line, the GEPON master station device 1-2 is connected to the normal line. The frame signal having the MAC address of the lower-level device as the transmission destination address is transmitted for several frames to the GEPON slave station device 1-5 from the use line at the time of abnormality. When receiving the frame signal, the GEPON slave station device 1-5 transmits several frames of the frame signal in which the transmission destination address of the frame signal is replaced with the transmission source address from the use line at the time of abnormality.

  As a result, the upper switch device 1-1 learns the correspondence between the connection port number of the line used in the event of an abnormality and the MAC address of the lower device of the GEPON slave station device 1-5 connected to the connection port. The upper switch apparatus 1-1 also recognizes the switching of the used line, and it is possible to avoid discarding the frame signal in the upper switch apparatus 1-1.

  In addition, after switching the use line from the normal use line to the abnormal use line, the normal use line is used from the GEPON master station device 1-2 to the GEPON slave station device 1-5 for settings other than the optical interface portion. The same setting information is written at the same time and the setting of the GEPON slave station device 1-5 is performed to control the data transmission / reception function of the GEPON slave station device 1-5.

  FIG. 2 shows the configuration of the GEPON master station device (OLT). As shown in the figure, the GEPON master station device (OLT) includes n interface boards (IF # 1, IF # 2,... IF # n) and an OLT control board. Here, it is assumed that the first interface board (IF # 1) and the second interface board (IF # 2) are connected to a normal use line and an abnormal use line for one GEPON slave station device. .

  In each interface board (IF # 1, IF # 2,...), The optical receiver 2-1 is an optical module that receives an optical signal of the PON interface, and converts the optical signal into an electrical signal. The optical transmission unit 2-2 is an optical module that converts an electrical signal into an optical signal of a PON interface and transmits the optical signal.

  The serial / parallel converter 2-3 changes the electrical serial signal output from the optical receiver 2-1 to an electrical parallel signal. The parallel / serial conversion unit 2-4 converts the parallel signal processed by the common unit (signal processing unit) 2-6 into a serial signal and outputs the serial signal to the signal deterioration detection unit 2-5.

  The signal degradation detection unit 2-5 performs signal degradation detection by CRC code error check of the parallel signal output from the serial / parallel conversion unit 2-3 or calculation of the number of packet loss, and the number of signal degradation occurrences within a predetermined time. Is detected to exceed a certain threshold value, the deterioration state of the received signal is notified to the common unit 2-6.

  The common unit 2-6 notifies the OLT control version 2-7 of the degradation state of the received signal input from the signal degradation detection unit 2-5, and OAM (Operation, Administration and Maintenance) from the GEPON slave station device When the frame is processed and reception deterioration information in the PON section is included in the OAM frame, the information is notified to the OLT control board 2-7.

  The common unit 2-6 sends the parallel signal output from the serial / parallel converter 2-3 to the upper switch device of the CNI interface, and the parallel signal input from the upper switch device is converted into the parallel / serial converter. Send to 2-4.

  The OLT control version 2-7 sets the line to be used to the common unit 2-6 of the first and second interface boards (IF # 1, IF # 2) based on the notification information of the degradation state of the received signal. A control signal for switching from the normal use line to the abnormal use line is transmitted.

  FIG. 3 shows the configuration of the GEPON slave station device (ONU). The GEPON slave station device (ONU) includes first and second transmission / reception units (# 1, # 2) as shown in FIG. Here, it is assumed that the first transmission / reception unit (# 1) is used in a normal state and the second transmission / reception unit (# 2) is used in an abnormal state.

  In the first and second transmission / reception units (# 1, # 2), the transmission unit 3-1 has a connection port of a PON interface, and is a serial electrical input from the user interface via the common unit 3-7. A signal is converted into an optical signal of a PON interface and a transmission optical module is provided.

  The reception unit 3-2 includes a connection port for the PON interface, and includes an optical module that receives an optical signal of the PON interface and converts it into an electrical signal. The reception serial / parallel conversion unit 3-3 converts the electrical serial signal output from the reception unit 3-2 into an electrical parallel signal.

  The signal reception degradation detection unit 3-4 performs signal degradation detection by CRC error check of the parallel electric signal output from the reception serial / parallel conversion unit 3-3 or calculation of the number of packet losses, and the signal degradation within a predetermined time. When the number of occurrences exceeds a certain threshold value, the common unit 3-7 is notified of the deterioration state of the received signal.

  The common unit 3-7 performs control of the GEPON slave station device (ONU), signal processing, switching of the used line when the quality of the used line is normal, etc., and the signal input from the signal reception deterioration detecting unit 3-4 Based on the reception deterioration detection status, a system selection signal for switching the used line to the used line at the time of abnormality is output to the transmission / reception system selection switch unit 3-5.

  The transmission parallel / serial conversion unit 3-6 converts the parallel signal input from the user interface and subjected to signal processing by the common unit 3-7 to serial, and outputs the serial signal to the transmission / reception system selection switch unit 3-5. The transmission / reception system selection switch unit 3-5 sends the serial frame signal output from the transmission parallel / serial conversion unit 3-6 to the first transmission / reception unit (# 1) or according to the system selection signal from the common unit 3-7. The data is output to one of the transmission units 3-1 of the second transmission / reception unit (# 2).

  Next, a flow of processing for switching from a normal use line to an abnormal use line will be described with reference to FIGS. FIG. 4 shows a process flow when line deterioration is detected by the GEPON slave station apparatus, and FIG. 5 shows a process flow when line deterioration is detected by the GEPON master station apparatus.

  As shown in FIG. 4, in the normal communication state (4-1), the GEPON slave station device performs handshake in the PON section by exchanging OAM frames with the GEPON master station device and the normal use line. The OAM frame also includes state information of the GEPON slave station device and the GEPON master station device.

  The signal reception degradation detection unit 3-4 of the GEPON slave station apparatus performs signal degradation detection by CRC code error check of the downlink signal coming from the GEPON master station apparatus or calculation of the number of packet losses (4-2) When the number of signal degradation occurrences within a predetermined time exceeds a certain threshold, the reception degradation information is notified to the common unit 3-7 (4-3).

  When receiving the reception deterioration information, the common unit 3-7 generates an OAM frame and notifies the GEPON master station device of the line deterioration information of the normal use line (# 1 system) (4-4). The common unit 3-7 issues a line switching command and sends a system selection signal for switching the used line to the transmission / reception system selection switch unit 3-5 (4-5).

  The transmission / reception system selection switch unit 3-5 switches the used line to the used line at the time of abnormality in response to the system selection signal from the common unit 3-7 (4-6). After that, for the frame signal transmitted from the GEPON master station device to the MAC address of the lower device of the own device, the frame signal in which the transmission destination address of the frame signal is replaced with the transmission source address is Transmit to the higher-level switch device (4-7).

  In the upper switch device of the GEPON master station device, the source MAC address of the frame signal received from the GEPON slave station device through the abnormal use line is associated with the port number of the port to which the abnormal use line is connected. And automatically recognizes that the line has been switched (4-8).

  When the line degradation is detected in the GEPON master station device, as shown in FIG. 5, in the normal communication state (5-1), the GEPON master station device is in the PON section by the GEPON slave station device and the normal use line. Handshake is performed by exchanging OAM frames. The signal degradation detection unit 2-5 of the GEPON master station apparatus performs signal degradation detection by checking the CRC code error of the upstream signal coming from the GEPON slave station apparatus or calculating the number of packet losses (5-2). When the number of signal degradation occurrences in time exceeds a certain threshold, the reception unit 2-6 is notified of reception degradation information (5-3).

  When receiving the reception deterioration information, the common unit 2-6 notifies the OLT control version 2-7 of the deterioration state of the received signal, and the OLT control version 2-7 receives the first and second interface boards (IF # 1). , IF # 2) transmits a control signal for switching the used line from the normal use line to the abnormal use line to the common unit 2-6, and the common unit 2-6 issues a line switching command (5- 4).

  The common unit 2-6 generates an OAM frame and transmits a line switching command for switching the used line to the used line at the time of an abnormality to the GEPON slave station apparatus (5-5). Further, in the GEPON master station device, the second interface board (IF # 2) side for the line used at the time of abnormality is switched to the active state (5-6).

  Thereafter, for a frame signal transmitted from the GEPON master station device to the MAC address of the lower-level device of the GEPON slave station device, a frame signal obtained by replacing the transmission destination address of the frame signal from the GEPON slave station device with the source address And transmits the frame signal to the upper switch device (5-7).

  In the upper switch device of the GEPON master station device, the source MAC address of the frame signal received from the GEPON slave station device through the abnormal use line is associated with the port number of the port to which the abnormal use line is connected. Automatically recognizes that the line has been switched (5-8)

It is a figure which shows the structure of the duplication system of GE-PON of this invention. It is a figure which shows the structure of the GEPON master station apparatus (OLT) of this invention. It is a figure which shows the structure of the GEPON subunit | mobile_unit apparatus (ONU) of this invention. It is a figure which shows the processing flow at the time of detecting line degradation in the GEPON subunit | mobile_unit apparatus by this invention. It is a figure which shows the processing flow at the time of detecting line degradation in the GEPON master station apparatus by this invention.

Explanation of symbols

1-1 Host switch device 1-2 GEPON master station device 1-3 Optical fiber cable 1-4 Photocoupler 1-5 GEPON slave station device

Claims (3)

In a GE-PON system in which one master station device and a plurality of slave station devices are connected by communication lines using a plurality of optical fiber cables and photocouplers,
The master station device and at least one slave station device are connected by two communication lines, a normal use line and an abnormal use line,
The slave station device connected to the master station device via the two communication lines includes a normal-time transmission / reception unit connected to the normal-use line and an abnormal-time transmission / reception unit connected to the abnormal-use line,
The normal-time transmission / reception unit and the abnormal-time transmission / reception unit include a signal reception deterioration detection unit that performs signal deterioration detection of a downlink signal transmitted from the master station device,
Based on the signal reception degradation detection status input from the signal reception degradation detection unit of the normal transmission / reception unit, outputs a system selection signal for switching the used line, and sends it to the upper switch device of the master station device to the lower level of its own device A common unit that transmits a frame signal with the MAC address of the side device as the source address,
A transmission / reception system selection switch unit that outputs a frame signal input from the user interface to either the normal-time transmission / reception unit or the abnormal-time transmission / reception unit by a system selection signal output from the common unit. Dual-line GE-PON system characterized by this. In a GE-PON system in which one master station device and a plurality of slave station devices are connected by communication lines using a plurality of optical fiber cables and photocouplers,
The master station device and at least one slave station device are connected by two communication lines, a normal use line and an abnormal use line,
The master station device connected to one slave station device via the two communication lines includes first and second interface boards connected to the normal use line and the abnormal use line,
The first and second interface boards each have a signal degradation detection unit and a common unit for performing signal degradation detection of an uplink signal transmitted from the slave station device,
Based on the signal reception deterioration detection status input from the signal deterioration detection unit, a control signal for switching the use line from the normal use line to the abnormal use line is provided to the first and second interface boards. With a control board to transmit,
When the control unit receives a control signal from the control board, the common unit of the first and second interface boards transmits a command to switch the used line to the slave station device, and is transmitted from the slave station device. In addition, a line duplex GE-PON system having a configuration for receiving a frame signal having a MAC address of a lower-level device of the slave station device as a transmission source address and transmitting the frame signal to a higher-level switch device. When the master station device switches from a normal use line to an abnormal use line, a frame signal having a MAC address of a lower-level device of the slave station device as a transmission destination address is transmitted from the abnormal use line to the slave station device. Send to
When the slave station device receives the frame signal from the abnormal use line, a frame signal having the transmission destination address of the frame signal as a transmission source address is sent back to the master station device from the abnormal use line,
The line duplex GE-PON system according to claim 1 or 2, wherein the master station device transmits a frame signal transmitted from the slave station device to the higher order switch device.

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