Monitoring device

Abstract

An object is to provide a monitoring device capable of acquiring ONU-specific information and connection information even in the case of an optical communication system with the MC system, and enabling optical fiber cable switching work to be finished in a short time. The monitoring device according to the present invention is a monitoring device that monitors an optical communication system in which an OLT and an ONU are connected by a communication optical fiber, and includes: an optical receiver for receiving a signal beam transmitted by the ONU from the communication optical fiber; and an OAM frame analysis unit for extracting, from the signal beam received by the optical receiver, an OAM frame at a MEG level at which the ONU and the OLT are set as monitoring end points, and acquiring a transmission source address and a MEG-ID that identifies a MEG in the OAM frame.

Claims

1. A monitoring device that monitors an optical communication system in which an optical line terminal (OLT) and an optical network unit (ONU) are connected by a communication optical fiber, the monitoring device comprising: an optical receiver for receiving a signal beam transmitted by the ONU from the communication optical fiber; an OAM (Operation Administration and Maintenance) frame analysis unit for extracting, from the signal beam received by the optical receiver, an OAM frame at a MEG (Maintenance Entity Group) level at which the ONU and the OLT are set as monitoring end points, and acquiring a transmission source address and a MEG-ID that identifies a MEG in the OAM frame; a storage unit for storing the transmission source address and the MEG-ID; and a determination unit for comparing, at the point in time, the transmission source address and the MEG-ID stored in the storage unit, and determining a state of the optical communication system, wherein the determination unit determines that the ONU has been incorrectly connected if the transmission source addresses do not match before and after the point in time, and the determination unit determines that the OLT has been incorrectly connected if the MEG-IDs do not match before and after the point in time.

2. The monitoring device according to claim 1, further comprising a signal type determination unit for detecting a MAC frame in the signal beam received by the optical receiver, determining a type of the optical communication system based on a preamble of the MAC frame, and transferring the signal beam to the OAM frame analysis unit if the optical communication system is of a point-to-point type.

3. A monitoring method of monitoring an optical communication system in which an optical line terminal (OLT) and an optical network unit (ONU) are connected by a communication optical fiber, the monitoring method comprising: receiving a signal beam transmitted by the ONU from the communication optical fiber; extracting, from the received signal beam, an OAM (Operation Administration and Maintenance) frame at a MEG (Maintenance Entity Group) level at which the ONU and the OLT are set as monitoring end points, and acquiring a transmission source address and a MEG-ID that identifies a MEG in the OAM frame; storing the transmission source address and the MEG-ID in a storage; and comparing, at a point in time, the transmission source address and the MEG-ID with the transmission source address and the MEG-ID stored in the storage, and determining a state of the optical communication system, wherein the ONU has been incorrectly connected if the transmission source addresses do not match before and after the point in time, and the OLT has been incorrectly connected if the MEG-IDs do not match before and after the point in time.

4. The monitoring method according to claim 3, further comprising: detecting a MAC frame in the received signal beam; determining a type of the optical communication system based on a preamble of the MAC frame; and extracting the OAM frame from the received signal beam if the optical communication system is of a point-to-point type.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a diagram illustrating an optical communication system with the MC system.

(2) FIG. 2 is a diagram illustrating an optical communication system with the PON system.

(3) FIG. 3 is a diagram illustrating an optical access network system in which the MC system and the PON system mix.

(4) FIG. 4 is a diagram illustrating a communication monitoring device for the MC system.

(5) FIG. 5 is a diagram illustrating a communication monitoring device for the PON system.

(6) FIG. 6 is a diagram illustrating a monitoring device according to the present invention.

(7) FIG. 7 illustrates optical fiber cable switching work using the monitoring device according to the present invention.

(8) FIG. 8 illustrates optical fiber cable switching work using the monitoring device according to the present invention.

(9) FIG. 9 is a diagram illustrating monitoring of an optical communication system using the monitoring device according to the present invention.

(10) FIG. 10 is a diagram illustrating monitoring of an optical communication system using the monitoring device according to the present invention.

DESCRIPTION OF EMBODIMENTS

(11) Embodiments of the present invention will be described with reference to the attached drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. Note that constituent elements with the same reference numerals in the specifications and the drawings are identical to each other.

(12) FIG. 6 is a functional block diagram of a communication monitoring device 10 according to the present embodiment. The communication monitoring device 10 is a monitoring device for monitoring an optical communication system in which an OLT and an ONU are connected by communication optical fibers, and includes an optical receiver 101, a signal type identification function unit 102, a PON signal processing function unit 103, an MC signal processing function unit 104, a PON communication monitoring function unit 105, an MC communication monitoring function unit 106, and a display function unit 107.

(13) The optical receiver 101 receives a signal beam (uplink optical signal) transmitted by the ONU from the communication optical fibers.

(14) The PON communication monitoring function unit 105 has an MPCP frame count table 1051 and a PON data frame count table 1053, which are stored in a memory (not shown), and a PON link establishment determination function unit 1052 and a PON communication state determination function unit 1054 for controlling access to these tables and updating thereof, respectively. Since the PON communication monitoring function unit 105 and frame processing are described in detail in PTL 2, description thereof is omitted here.

(15) The MC communication monitoring function unit 106 has an MC data frame count table 1061, which is stored in a memory (not shown), an MC communication state determination function unit 1062 for controlling access to this table and updating thereof, and an OAM frame analysis unit 1063. The OAM frame analysis unit 1063 extracts, from the signal beam received by the optical receiver 101, an OAM (Operation Administration and Maintenance) frame at MEG (Maintenance Entity Group) level at which the ONU and the OLT are set as monitoring end points, and acquires a transmission source address and an MEG-ID that identifies the MEG in the OAM frame.

(16) The signal type determination unit 102 detects a MAC frame in the signal beam received by the optical receiver 101, and determines the type of the optical communication system based on a preamble of the MAC frame. If the optical communication system is of a point-to-point type, the signal type determination unit 102 transfers the signal beam to the OAM frame analysis unit 1063.

(17) In the optical access network system such as that shown in FIG. 3, the communication monitoring device 10 connects an uplink optical signal from the ONUs 2-N to the OLTs 3-N to the optical couplers 5-N on an optical fiber transmission path. The optical receiver 101 receives the uplink optical signal, which is regarded as a received signal, and the signal type determination unit 102 determines whether this uplink optical signal is communication using the MC system or communication using the PON system, based on a difference (presence of an LLID etc.) in the preamble in the MAC frame in the received signal.

(18) If the uplink optical signal is communication using the PON system, the signal type determination unit 102 transfers the received signal to the PON signal processing unit 103. The PON signal processing unit 103 and the PON communication monitoring function unit 105 check the unique ID (e.g. MAC address) of each ONU 2-N, the connection state between each ONU 2-N and the OLT 3-N, and the state of communication with each priority for each ONU 2-N. The display function unit 107 then displays the unique ID, the connection state, and the state of communication with each priority on a predetermined display screen.

(19) If the uplink optical signal is communication using the MC system, the signal type determination unit 102 transfers the received signal to the MC signal processing unit 104. The MC signal processing unit 104 and the MC communication monitoring function unit 106 checks the unique ID of the ONU 2-N, the connection state (ID indication) between the ONU 2-N and the OLT 3-N, and the state of communication with each priority for each ONU 2-N. The display function unit 107 then displays the unique ID, the connection state, and the state of communication with each priority on a predetermined display screen using the display function unit 107.

(20) Here, it will be described that the check of the unique ID of the ONU 2-N, the connection state (ID indication) between the ONU 2-N and the OLT 3-N, and the state of communication with each priority of each ONU 2-N in the case of the MC system can be realized through processing performed by the OAM frame analysis unit 1063.

(21) The present embodiment will give a description while taking an example using an Ethernet (registered trademark) OAM technology for connection monitoring in a communication network described in ITU-T Y.1731 (see NPL 1 and NPL 2). Note that, in addition to the Ethernet (registered trademark) OAM technology, the check can be performed using a similar procedure if a frame transmitted and received between the OLT and the ONU includes information with which the ONU and the OLT can be identified, and there is a means capable of identifying the aforementioned frame.

(22) In the Ethernet (registered trademark) OAM technology, a device located at a monitoring end point is set as an MEP (MEG End Point). A plurality of MEGs (Maintenance Entity Groups) can be set as a monitoring group that includes the MEP. Also, domains of OAM functional units are configured for each of a plurality of tiered maintenance levels, which are referred to as customer level, provider level, and operator level. These domains are called MEG levels.

(23) In the Ethernet (registered trademark) OAM technology, an MEG-ID is given as an identifier that uniquely identifies a MEG at each MEG level, and enables detection of a line failure that has occurred in the MEG by regularly transmitting and receiving a MAC frame called an OAM frame for monitoring between devices in the MEG.

(24) Here, attention is paid to the MEG level at which the OLT and the ONU are set as the MEPs, and the given MEG-ID is sent out from the OLT side to the ONU side and stored in an internal memory of the ONU. OAM frames that contain the MEG-ID is also regularly transmitted and received between the OLT and the ONU.

(25) The MC signal processing function unit 104 acquires OAM frames from the ONU in the received signal.

(26) The OAM frame analysis unit 1063 extracts an OAM frame at the MEG level at which the ONU and the OLT are monitoring end points, from the OAM frames from the ONU. Then, the OAM frame analysis unit 1063 outputs, to the display unit 107, the transmission source address in this OAM frame as the unique ID of the ONU, and the MEG-ID in the OAM frame as the unique ID that identifies the MEG that includes the OLT.

(27) Meanwhile, the MC communication state determination unit 1062 reads out a user priority bit (priority) of a VLAN of data frames, and counts the data frames for each priority in a predetermined time of an observation period. The MC communication state determination unit 1062 stores the count result as the state of communication with each priority in the MC data frame count table 1061, and outputs the count result to the display unit 107.

(28) FIGS. 7 and 8 are diagrams illustrating optical fiber cable switching work using the communication monitoring device 10. External output of the communication monitoring device 10 is connected to a storage unit 20 and a determination unit 30. Here, the storage unit 20 stores the aforementioned transmission source address and MEG-ID acquired by the OAM frame analysis unit 1063. The determination unit 30 compares, at a point in time, the transmission source address and the MEG-ID acquired by the OAM frame analysis unit 1063 with the transmission source address and the MEG-ID stored in the storage unit 20, and determines the state of the optical communication system. If the transmission source address does not match before or after that point in time, the determination unit 30 determines that the ONU has been incorrectly connected, and if the MEG-ID does not match, the determination unit 30 determines that the OLT has been incorrectly connected.

(29) FIG. 7 illustrates switching of an optical fiber cable 50 between a communication equipment building and a user's house. OLTs 3-N and ONUs 2-N are set as MEPs, which are assigned a MEG-ID. As shown in FIG. 7(a), the communication monitoring device 10 is connected to an optical coupler in the optical fiber termination stand 5, and the transmission source address (BBB123) and the MEG-ID (YYY111) before the switching of the optical fiber cable 50 are stored in the communication monitoring device 10.

(30) As shown in FIG. 7(b), if the optical fiber cable 50 is correctly switched to an optical fiber cable 51, the transmission source address and the MEG-ID match before and after the switching of the optical fiber cable. For this reason, the operator or the determination unit 30 of the communication monitoring device 10 determines that the optical fiber has been correctly switched.

(31) On the other hand, if the optical fiber cable 50 is incorrectly switched to an optical fiber cable 52 and connected to a different ONU as shown in FIG. 7(c), the transmission source address is BBB123 before the switching of the optical fiber cable, but is AAA123 after the switching. Since the transmission source address differs before and after the switching of the optical fiber cable, the operator or the determination unit 30 of the communication monitoring device 10 can determine that the optical fiber has been incorrectly switched (incorrect connection).

(32) FIG. 8 illustrates switching of an optical fiber cable between an OLT 3-N and the optical fiber termination stand 5 in a communication equipment building. The OLT 3-N and an ONU 2-N are set as MEPs, which are assigned a MEG-ID. As shown in FIG. 8(a), the communication monitoring device 10 is connected to an optical coupler in the optical fiber termination stand 5, and the transmission source address (BBB123) and the MEG-ID (YYY111) are stored in the communication monitoring device 10 before the switching of the optical fiber cable 50.

(33) As shown in FIG. 8(b), if the optical fiber cable 50 is correctly switched to an optical fiber cable 51 in the communication equipment building, the transmission source address and the MEG-ID match before and after the switching of the optical fiber cable. For this reason, the operator or the determination unit 30 of the communication monitoring device 10 determines that the optical fiber has been correctly switched.

(34) On the other hand, if the optical fiber cable 50 is incorrectly switched to an optical fiber cable 52 and connected to a different OLT in the communication equipment building as shown in FIG. 8(c), a new MEG-ID (XXX111) is sent from the OLT to the ONU, and the new MEG-ID (XXX111) is sent from the ONU to the communication monitoring device 10. Since the MEG-ID differs before and after the switching of the optical fiber cable, the operator or the determination unit 30 of the communication monitoring device 10 can determine that the optical fiber has been incorrectly switched (incorrect connection).

(35) Thus, the use of the communication monitoring device 10 is also helpful in specifying a cause in the case of an incorrect switching, in addition to the determination that an optical fiber cable has been correctly switched.

(36) In the present embodiment, an OLT 3-N and an ONU 2-N are used as MEPs. As another embodiment, a MEG-ID assigned to MEGs that are an ONU 2-N and a relay device 11 connected to an OLT 3-N, and a transmission source address of the ONU may alternatively be used, as shown in FIG. 9. Also, as another embodiment, a MEG-ID assigned to MEPs that are terminal devices 1-N connected to respective ONUs 2-N, and a transmission source address of a terminal devices 1-N may alternatively be used, as shown in FIG. 10.

(37) [Supplementary Note] The following is a description of the communication monitoring device according to the present embodiment.

(38) (1):

(39) In an optical communication system in which an OLT and an ONU are connected by one or more communication optical fibers, the communication monitoring device is connected to

(40) an optical coupler for splitting a signal beam propagated from the ONU through the communication optical fibers, to cause the signal beam to flow toward an optical fiber for measurement, the optical coupler being disposed between the OLT and the ONU on the communication optical fiber, and

(41) to the optical fiber for measurement, acquires an identifier from the signal beam propagated from the connected ONU, checks the acquired identifier against identifier stored in advance, and

(42) uses, as the identifier, an address that identifies a management unit of the OLT and the ONU.

(43) (2):

(44) The communication monitoring device according to (1) above, which is connected to the optical fiber for measurement, acquires an identifier from a signal beam propagated from the connected ONU, and checks the acquired identifies against the identifies stored in advance,

(45) uses, as the identifier, the address that identifies the management unit of the OLT and the ONU described in (1) above, and a transmission source address described in a frame of the signal beam propagated from the ONU.

(46) (3):

(47) In the communication monitoring device according to (1) or (2) above, which is connected to the optical fiber for measurement, acquires an identifier from a signal beam propagated from the connected ONU, and checks the acquired identifies against the identifies stored in advance,

(48) determines, when connected to an optical fiber, whether a transmission method is of a point-to-point type or a point-to-multipoint (P2MP) type, based on the signal beam from the ONU, and performs processing described in (1) or (2) above only if the transmission method is of the point-to-point type.

(49) Effects

(50) By determining an optical communication system with the MC system and a connection state, an on-site operator can promptly determine whether or not an optical fiber cable has been correctly switched in optical fiber cable switching work.

(51) In addition, the switching of an optical fiber cable can be finished in a short time without placing a burden on an operator in an operation center, and the present invention also contributes to service improvement for users, including prevention of incorrect connection, shortening of the time during which the service is not available, and so on.

(52) In the case of an incorrect connection, whether it has occurred on the OLT side or the ONU side can be determined, and it is therefore possible to recheck and reconnect the optical fiber in a short time.

INDUSTRIAL APPLICABILITY

(53) The monitoring device according to the present invention can be applied to not only Gigabit Ethernet (registered trademark) as in the embodiments, but also other standards (Ethernet (registered trademark) with a communication speed of 100 Mbps or 10 Gbps, for example).

REFERENCE SIGNS LIST

(54) 1, 1-N Communication terminal 2, 2-N ONU 3, 3-N OLT 4 Optical splitter 5 Optical fiber termination stand 6 Service demultiplexing device 7 OTDR 8 MC communication monitoring device 9 PON communication monitoring device 10 Communication monitoring device 11 Relay device 20 Storage unit 30 Determination unit 50, 51, 52 Optical fiber cable 81 Optical receiver 82 MC signal processing unit 83 Display unit 91 Optical receiver 92 PON signal processing unit 93 Display unit 101 Optical receiver 102 Signal type identification function unit 103 PON signal processing function unit 104 MC signal processing function unit 105 PON communication monitoring function unit 106 MC communication monitoring function unit 107 Display function unit 1051 MPCP frame counter table 1052 PON link establishment determination unit 1053 PON data frame counter table 1054 PON communication state determination unit 1061 MC data frame counter table 1062 MC communication state determination unit 1063 OAM frame analysis unit