JP2007228031A - Optical communication network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical network in which a terminal station apparatus can accurately and quickly judge a fault in a relaying apparatus. <P>SOLUTION: The relaying apparatus includes: a fault detection section for detecting a fault in incoming and outgoing transmitter-receivers; and a fault information notice section for writing fault information including identification information of the relay apparatus to section management information of a transmission signal relayed by a transmitter-receiver whose fault is not detected when the fault detection section detects a fault in one of the incoming and outgoing transmitters. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical communication network, and more particularly to an optical communication network capable of notifying terminal station devices and the like of circuit failure information of relay devices.

  In recent years, high-speed digital transmission networks have been widely used with the spread of the Internet and the development of subscriber optical access networks such as FTTH (Fiber To The Home). Such digital transmission devices include high-speed digital communication systems such as SDH (Synchronous Digital Hierarchy) and SONET (Synchronous Optical NETwork).

  Such a digital transmission system includes various functions related to operation management. Among them, a management function in the event of a failure is very important. In other words, failure location identification, failure notification function, and path switching function when a failure occurs are important (see, for example, Patent Document 1).

  For example, in a transmission line using the SDH interface, section management information (SOH: section overhead) is used to perform alarm transfer in the intermediate relay section. SOH is management information for maintenance / operation added to a virtual container (VC), and is information for transferring maintenance information such as path / section operation status display and error monitoring. For example, it is specified that a predetermined byte of the SOH, for example, a byte called F1 byte indicates failure identification.

  FIG. 1 is a diagram showing a frame format (conforming to TTC standard JT-G707) of STM-0 (STM: Synchronous Transport Module) which is a synchronous transfer mode.

  As shown in the figure, the STM-0 frame consists of three areas, namely, overhead, AU pointer, and payload. The overhead is composed of SOH of 3 rows 3 bytes and 5 rows 3 bytes, that is, a relay section overhead (R-SOH) and a terminal station section overhead (M-SOH), respectively. It is specified that one VC-3 and fixed stuff (FS) are accommodated in the payload, and the head position is specified by the H1 and H2 bytes.

  FIG. 2 is a diagram showing a general definition of the F1 byte indicating failure identification of the intermediate relay device in the section management information (SOH).

  The first and second bits of the F1 byte, that is, the b1 and b2 bits (R section) indicate a detection alarm, and the third to eighth bits (b3 to b8 bits) are identification numbers of the intermediate relay apparatuses in which the abnormality is detected. (ID) is shown.

The R section indicates a normal state when “00”, and indicates that a failure is detected when “01”, “10”, and “11”. More specifically, when the R section is “10”, this indicates that an input signal loss or loss of frame synchronization has been detected (the failure is expressed as “REC”). Further, “01” and “11” indicate that an error (the failure is expressed as “MAJ ERR” and “ERR MON”, respectively) is detected by error monitoring (BIP-N calculation).
FIG. 3 shows the terminal device 111 and 112 and the relay devices 121, 122, and 123 arranged between the terminal devices 111 and 112.

  Bidirectional transmission paths 131, 132, 133, and 134 are provided between the terminal device 111, the relay devices 121, 122, 123, and the terminal device 112, respectively. Note that the direction from the terminal station device 111 to the terminal station device 112 is assumed to be an upward direction, and the direction from the terminal station device 112 to the terminal station device 111 is assumed to be a downward direction. In addition, a transmission / reception circuit of a relay device to be described later will be described by adding subscripts A and B, respectively, and distinguishing between an upstream direction and a downstream direction.

In the network shown in FIG. 3, a case will be described where the transmission / reception circuit 121A (TR-A) in the direction (upward direction) from the terminal station device 111 to the terminal device 112 in the relay apparatus 121 fails. In this case, the relay device 122 issues an F1 byte (“10000002”) representing “REC + (ID = 2)”. The relay device 123 sends this F1 byte as it is to the transmission line 134, and the terminal device 112 receives this F1 byte. However, the F1 byte has the same content (“10000002”) as that when the transmission path 132 fails. Further, the terminal device 111 performs normal reception (normal reception). Therefore, if the failure location is determined from these pieces of information, the relay device 121 and the transmission path 132 are suspected, and it takes time to determine the failure location.
JP 2001-217901 A (page 3, FIG. 1)

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide an optical network capable of accurately and quickly determining a failure of a relay device at a terminal device. And

  The optical communication network of the present invention includes a first and a second terminal device and a relay including an uplink and a downlink transmitter / receiver for respectively relaying uplink and downlink synchronous digital transmission signals between the first and second terminal devices. An optical communication network including a device, wherein the relay device detects a failure in the uplink and downlink transceivers, and a failure is detected in any one of the uplink and downlink transceivers in the failure detection unit. A failure information notifying unit that writes failure information including identification information of the relay device into section management information of a transmission signal relayed by a transmitter / receiver in which no failure has been detected.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings described below, substantially the same or equivalent components and parts are denoted by the same reference numerals.

  FIG. 4 is a block diagram schematically showing the configuration of the optical network 10 according to the present invention. The optical network 10 includes first and second terminal devices (# 1, # 2) 11 and 12, and at least one relay device arranged between the terminal devices 11 and 12. In this embodiment, three relay apparatuses, that is, relay apparatuses 21, 22, and 23 are arranged in order from the terminal station 11 side.

  Transmission paths 31, 32, 33, and 34 are provided between the terminal station device (# 1) 11, the relay devices 21, 22, 23, and the terminal station device (# 2) 12, respectively. The transmission lines 31, 32, 33, and 34 are bidirectional optical transmission lines using optical fibers.

  For convenience of explanation, the direction from the terminal station apparatus 11 to the terminal station apparatus 12 will be described as an upstream direction, and the direction from the terminal station apparatus 12 to the terminal station apparatus 11 will be described as a downstream direction. In addition, a transmission / reception circuit of a relay device to be described later will be described by adding subscripts A and B, respectively, and distinguishing between an upstream direction and a downstream direction.

  In the present embodiment, in the relay device 21 of the optical network 10 shown in FIG. 4, the transmission / reception circuit 21A (TR-A) in the direction (upward direction) from the terminal station device 11 to the terminal device 12 fails. Will be described as an example.

  FIG. 5 is a block diagram schematically showing the configuration of the relay device 21. The relay device 21 is configured as an SDH relay device. The relay device 21 includes an upstream transmission / reception circuit 21A, a downstream transmission / reception circuit 21B, and a failure monitoring circuit 40.

  The upstream transmission / reception circuit 21 </ b> A receives the upstream optical signal from the first terminal device (# 1) 11, which is the preceding device, via the transmission line 31.

  The received signal is converted into an electrical signal by an upstream opto-electric converter (hereinafter referred to as O / E converter) 41 and supplied to the upstream SOH processing unit 42. In the upstream SOH processing unit 42, the received signal is subjected to serial-parallel conversion, and then subjected to SOH reception processing and SOH transmission processing. After these SOH processes are performed, parallel-serial conversion is performed. In the SOH processing unit, processing such as BIP (Bit Interleaved Parity) calculation is performed. More specifically, BIP calculation (BIP-8 calculation) results are matched in the reception process of the SOH processing unit. In addition, SOH data such as BIP data is generated and placed in a signal during transmission processing.

  By such SOH processing, it is possible to determine a transmission line failure and a transmission / reception circuit failure. After these SOH treatments, the light is converted into an optical signal by an electro-optical converter (hereinafter referred to as E / O converter) 43 and sent to the transmission path 32.

  Similar signal processing is performed in the transmission / reception circuit 21B in the downstream direction. That is, the transmission / reception circuit 21B receives a downstream optical signal via the transmission path 32 from the relay device 22 which is a preceding device. The received optical signal is photoelectrically converted by the O / E converter 44, SOH processing is performed by the SOH processing unit 45, and then the electrical / optical conversion is performed by the E / O converter 46, which is sent to the transmission line 31. Is done.

  The optical signal processing circuits such as the O / E converters 41 and 44 and the E / O converters 43 and 46 are configured as optical modules, and the SOH processing units 42 and 45 are programmable LSIs such as FPGAs. (Field Programmable Gate Array), but is not limited thereto.

  The failure monitoring circuit 40 monitors the operation of the relay device 21 and detects a predetermined failure. For example, the internal voltage level is monitored and the operation of the mounted optical module is monitored. Further, it is determined which of the upstream transmission / reception circuit 21A and the downstream transmission / reception circuit 21B has failed.

  Further, when a failure is detected, the failure monitoring circuit 40 uses a predetermined byte of the section management information (SOH), that is, one byte of unused or undefined bytes (hereinafter referred to as X byte). An alarm indicating that a failure has occurred in the relay device 21 is issued.

  As the byte used for the X byte, for example, any one of D1 to D12 and Z1 to Z2 bytes which are not defined in TTC standard G.707 can be used. Note that if the relay device 21 is operating normally without a failure, the received data is passed through without being processed.

  FIG. 6 is a diagram showing the definition of the X byte described above. The first and second bits of the X byte, that is, the b1 and b2 bits (hereinafter referred to as R2-section) indicate a detection alarm, and the third to eighth bits (b3 to b8 bits) are intermediate points where a failure is detected. It is defined to indicate an identification number (ID) of the relay device.

  More specifically, the R2-section indicates a normal state when “00”, and indicates that a failure of the device itself is detected when “01”. For example, when a device failure of the relay device 21 (identification number ID = 1) is detected, data (“01000001”) is generated and issued as X bytes (see FIG. 4).

  As shown in FIG. 4, the F1 byte (“10000002”) representing “REC + ID” is issued from the relay device 22 (ID = 2) at the next stage in the upstream direction. Further, the relay device 23 receives this F1 byte and sends it to the transmission line 34 as it is. Then, the terminal device 12 receives this F1 byte.

  FIG. 7 is a block diagram schematically illustrating an example of a detailed configuration of the failure monitoring circuit 40 in order to describe the function / operation of the failure monitoring circuit 40 in more detail. The failure monitoring circuit 40 includes a failure detection unit 40A that detects a device failure of the relay device 21, a failure transmission / reception circuit determination unit 40B, and a failure information notification (uplink / downlink SOH data generation) unit 40C.

  The failure transmission / reception circuit determination unit 40B determines whether the failure has occurred in the upstream transmission / reception circuit 21A or the downstream transmission / reception circuit 21B. Then, the failure transmitting / receiving circuit determination unit 40B supplies the determination result to the failure notification (up / down SOH data generation) unit 40C.

  The failure information notification unit 40C uses the determination result from the failure transmission / reception circuit determination unit 40B in response to the detection of the device failure in the failure detection unit 40A, and the section of the transmission signal relayed by the transmitter / receiver in which no failure is detected. It operates to write failure information including identification information of the relay device in the management information.

  More specifically, the failure information notification unit 40C has a function of generating uplink / downlink SOH data. The failure information notification unit 40C generates X bytes whose data is “01000001” (data indicating failure occurrence and device identifier) based on the determination result from the failure transmission / reception circuit determination unit 40B. Furthermore, when the failure information notification unit 40C determines that the failure has occurred in the upstream transmission / reception circuit 21A in the failure transmission / reception circuit determination unit 40B, the other transmission / reception circuit in which no failure has occurred, that is, The generated X byte ("01000001") is supplied to the downlink SOH processing unit 45 of the downlink transmission / reception circuit 21B to notify the failure information. That is, the downstream SOH processing unit 45 overwrites and rewrites the X byte in the SOH of the downstream signal with the supplied X byte ("01000001"). Then, the failure information is notified to the first terminal device (# 1) 11 by transmitting the SOH including the X byte in the downstream direction.

  On the other hand, if it is determined that a failure has occurred in the downlink transmission / reception circuit 21B, it is generated for the other transmission / reception circuit in which no failure has occurred, that is, the uplink SOH processing unit 42 of the uplink transmission / reception circuit 21A. The supplied X byte ("01000001") is supplied to notify the failure information. That is, the upstream SOH processing unit 42 rewrites the supplied X byte (“01000001”) by overwriting the X byte in the SOH of the upstream signal. Then, the failure information is notified to the second terminal device (# 2) 12 by transmitting the SOH including the X byte in the upstream direction.

  In addition, although the case where the failure information notification unit 40C is configured to generate the X-byte data (“01000001”) indicating the failure occurrence and the device identifier has been described as an example, the present invention is not limited thereto. For example, the failure information notification unit 40C sends a data generation instruction signal instructing to generate the X-byte data (“01000001”) to the downstream SOH processing unit 45 or the upstream SOH processing unit 42, and the downstream SOH processing unit 45 Alternatively, the upstream SOH processing unit 42 may be configured to rewrite the X byte of the SOH with data indicating the failure occurrence and the device identifier (“01000001”).

  As described above, when a failure occurs, the X byte in the SOH of the transmission signal is rewritten and transferred to data representing the failure occurrence and the device identifier. Then, the first terminal device (# 1) 11 or the second terminal device (# 2) 12 determines that a failure has occurred in the relay device 21 from the X byte of the SOH.

  Further, the terminal devices 11 and 12 monitor the X byte of the SOH of the transmission signal and extract the occurrence of a failure in the relay device and the identification number (ie, failure information) of the relay device in which the failure has occurred from the X byte. A failure information extraction unit (not shown) is provided.

  In the above-described embodiment, the case where a failure has occurred in the upstream transmission / reception circuit 21A of the relay device 21 has been described as an example. The same applies to the case where a failure occurs in any one of the relay devices 22, 23, 24 other than the relay device 21.

  Further, in the above-described embodiment, the up direction and the down direction are provided for convenience, and any of them may be the up direction or the down direction. Further, the case of a bidirectional transmission path in which the upstream direction and the downstream direction are configured by one optical fiber has been described. However, this is the case of an optical network in which the upstream direction and the downstream direction are each configured by different optical fibers. However, the same can be applied.

  Furthermore, although the case where the transmission network is an SDH transmission system and STM-0 transmission has been described as an example, the present invention is not limited thereto. For example, a SONET transmission system or a transmission system formed by connecting SONET / SDH, or an STM-1, 4, 16, or OC-3, 12, 48 transmission system is similarly applied. be able to.

  As described above in detail, when a failure occurs in the optical network, it is possible to provide an optical network in which a failure of the relay device can be accurately and quickly determined by the terminal device.

  The above-described embodiments are merely examples. In addition, the above-described embodiments can be applied with appropriate modifications and combinations.

It is a figure which shows the frame format (compliant with TTC standard JT-G707) of STM-0 which is a synchronous transfer mode. It is a figure which shows the general definition of F1 byte which makes a failure specification in section management information (SOH). It is a block diagram which shows typically the structure of the optical network which has a terminal station apparatus and the relay apparatus distribute | arranged between the said terminal station apparatuses. It is a block diagram which shows typically the structure of the optical network by this invention. It is a block diagram which shows typically the structure of the SDH relay apparatus shown in FIG. It is a figure which shows the definition of X byte of the section management information (SOH) in which failure information is written. FIG. 3 is a block diagram schematically illustrating an example of a detailed configuration of a failure monitoring circuit in order to explain functions and operations of the failure monitoring circuit in more detail.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical network 11, 12 Terminal station apparatus 21, 22, 23 Relay apparatus 21A Up direction transmission / reception circuit 21B Down direction transmission / reception circuit 31, 32, 33, 34 Transmission path 40 Failure monitoring circuit 40A Failure detection part 40B Failure transmission / reception circuit discrimination | determination part 40C Failure information notification unit 41, 44 O / E converter 42, 45 SOH processing unit 43, 46 E / O converter

Claims (4)

An optical communication network comprising first and second terminal devices, and a relay device including uplink and downlink transceivers that relay uplink and downlink synchronous digital transmission signals between the first and second terminal devices, respectively. There,
The relay apparatus detects a failure when a failure is detected in any one of the uplink and downlink transceivers in the failure detection unit and a failure detection unit that detects a failure of the uplink and downlink transceivers. An optical communication network, comprising: a failure information notifying unit that writes failure information including identification information of the relay device in section management information of a transmission signal relayed by a non-transmitter / receiver.   The optical communication network according to claim 1, wherein the failure information notification unit writes the failure information in any one of a plurality of unit blocks constituting the section management information.   2. The optical communication network according to claim 1, wherein the synchronous digital transmission conforms to an SDH standard, and one of the unit blocks is one of undefined bytes in the SDH standard.   The optical communication network according to claim 1, wherein the terminal device includes a failure information extraction unit that extracts the failure information from the section management information received from the relay device.

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