JP2013197690A - Pon system, onu and olt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress interruption of an optical access service in the event of a failure with low installation cost, and to provide a user with a communication path having a bandwidth wider than in the conventional PON system.SOLUTION: An ONU 4 includes a plurality of PON interfaces 41, 42 connected to an OLT 1 through different communication paths. The OLT 1 includes: optical transceiver units 11, 12 for transmitting/receiving signals to/from each ONU 4 through the PON interfaces 41, 42; communication parameter monitoring control units 13, 14 for acquiring parameters indicative of communication quality of the communication paths from the optical transceiver units 11, 12, and for detecting abnormality of the communication paths on the basis of the parameters; a switch unit 16 for selecting a communication path to be used; and a switch control unit 15 for instructing the switch unit 16 to switch over the communication path on the basis of the monitoring results by the communication parameter monitoring control units 13, 14.

Description

  The present invention relates to a PON (Passive Optical Network) system in which a plurality of in-house terminal devices (ONUs) are connected to an optical line terminal (OLT) through an optical branching unit. In particular, the present invention relates to a PON system, ONU, and OLT having a redundant path in a PON section for the purpose of improving communication quality.

  One of methods for providing users with optical access services such as FTTH (Fiber To The Home) is a passive optical network (PON). In this PON system, a high-speed access service using an optical fiber can be provided at low cost by adopting a star-type connection form in which a plurality of ONUs share an OLT and a transmission path (optical fiber).

  In a conventional PON system, when a failure occurs in a communication path between a server located in an upper network of an OLT that provides content to a user and a user terminal device that performs optical communication using the PON system via an ONU There is a problem that the optical access service is interrupted until the network manager detects the failure and eliminates the failure.

  As a measure to improve this, a PON equipped with a redundant path that enables the communication path to be switched when a failure occurs by duplicating the physical path in the communication path between the OLT and the upper network of the OLT or the communication path in the PON section. A system is defined (see, for example, Patent Documents 1 and 2).

  In the PON system disclosed in Patent Document 1, the physical path between the OLT and the upper network of the OLT is configured to be duplicated. When a failure occurs in an NNI (Network Node Interface), which is an upper interface of the OLT, the communication path is dynamically switched according to the communication status of the NNI port. As a result, it is possible to prevent traffic from being concentrated on one NNI port and, as a result, congestion in the PON section.

  In the PON system disclosed in Patent Document 2, the physical path of the PON section is duplicated, and when a failure such as erroneous light emission occurs in one PON section, the communication path is secured by switching to the communication path of the other PON. To do. In this PON system, assuming that the ONU has one PON interface, two communication paths are secured in the PON section using two ONUs. Therefore, the PON section duplication function can be realized relatively easily.

JP 2010-193056 A JP 2004-179723 A

However, the PON system of Patent Document 1 has a problem that it is difficult to maintain an optical access service for a plurality of ONUs connected under the OLT when a failure occurs in the PON section.
Further, in the PON system of Patent Document 2, even when a failure occurs in the PON section, it is possible to maintain an optical access service by adopting a redundant configuration and selecting the other communication path in which no failure has occurred. It becomes. However, there is a problem that installation cost is high.

  The present invention has been made in order to solve the above-described problems, and it is possible to suppress interruption of the optical access service even when a failure occurs in the PON section at a low installation cost. An object of the present invention is to provide a PON system, an ONU, and an OLT that can provide a user with a wider communication path than a conventional PON system by providing the system.

  The PON system according to the present invention includes a plurality of ONUs and OLTs connected to the respective ONUs, the ONU includes a plurality of PON interfaces connected to the OLTs through different communication paths, and the OLT is connected via the PON interface. Communication parameter monitoring control for acquiring a parameter indicating the communication quality of the communication path from the optical transmitter / receiver and detecting an abnormality of the communication path based on the parameter , A switch unit for selecting a communication path to be used, and a switch control unit for instructing the switch unit to switch the communication path based on a monitoring result by the communication parameter monitoring control unit.

  According to the present invention, the optical access service is provided to the user even when a failure occurs in the PON section, except when a failure occurs in all of the plurality of communication paths between the OLT and the ONU. Can be provided continuously. In addition, as a means for securing a plurality of communication paths between the OLT and the ONU, since the ONU is provided with a plurality of PON interfaces, it is high quality for the user at a lower installation cost than the PON system of Patent Document 2. It is possible to provide services.

It is a figure which shows the whole structure of the PON system which concerns on Embodiment 1 of this invention. It is a figure which shows the management format of the authentication database in Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the PON system which concerns on Embodiment 1 of this invention. It is a figure which shows the whole structure of the PON system which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a diagram showing an overall configuration of a PON system according to Embodiment 1 of the present invention.
In the PON system, as shown in FIG. 1, a single station side line terminating device (hereinafter referred to as OLT) 1 has a plurality of in-house terminal devices (hereinafter referred to as ONU) 4 via optical branching devices 2 and 3. -1 to 4-n are connected. Further, subscriber terminals 5-1 to 5-n, which are lower-level terminals, are connected to the ONUs 4-1 to 4-n.
In the following description, the ONUs 4-1 to 4-n and the subscriber terminals 5-1 to 5-n are simply referred to as the ONU 4 and the subscriber terminal 5 unless it is necessary to distinguish between them.

The ONU 4 includes a plurality of (2 ports in the figure) PON interfaces 41 and 42 so as to secure at least two communication paths in the PON section. For example, in FIG. 1, the ONU 4-1 secures two physical paths with the OLT 1 using the PON interfaces 41-1 and 42-1. The ONU 4-n secures two physical paths with the OLT 1 using the PON interfaces 41-n and 42-n.
When the ONU 4 receives an uplink communication frame from the subscriber terminal 5, the ONU 4 duplicates the uplink communication frame and transfers it to each communication path via the PON interfaces 41 and 42 holding the uplink communication frame. .

  On the other hand, the OLT 1 includes optical transmission / reception units 11 and 12, communication parameter monitoring control units 13 and 14, a switch control unit 15, a switch unit 16, and an authentication database 17.

The optical transmission / reception unit 11 transmits / receives signals to / from each ONU 4 via the PON interface 41.
The optical transmission / reception unit 12 transmits / receives signals to / from each ONU 4 via the PON interface 42.

The communication parameter monitoring control unit 13 periodically acquires a predetermined parameter (a parameter indicating the communication quality of the communication path between the OLT 1 and the ONU 4 connected under the optical transmission / reception unit 11) from the optical transmission / reception unit 11, and the parameter Based on the above, an abnormality in each communication path is detected. When the acquired parameter is outside the threshold range set by the network administrator, the communication parameter monitoring control unit 13 detects that a failure has occurred in its communication path, and sends a communication path alarm to the switch control unit 15. Notice.
The communication parameter monitoring control unit 14 periodically acquires a predetermined parameter (a parameter indicating the communication quality of the communication path between the OLT 1 and the ONU 4 connected under the optical transmission / reception unit 12) from the optical transmission / reception unit 12, and the parameter Based on the above, an abnormality in each communication path is detected. When the acquired parameter is outside the threshold range set by the network administrator, the communication parameter monitoring control unit 14 detects that a failure has occurred in its communication path, and sends a communication path alarm to the switch control unit 15. Notice.

Here, the parameters acquired by the communication parameter monitoring control unit 13 include the optical transmission output power of the optical transmission / reception unit 11, the received light power from the ONU 4 input to the optical transmission / reception unit 11, the operating temperature of the optical transmission / reception unit 11, light The power supply voltage of the transmission / reception unit 11, the bias current of the optical transmission / reception unit 11, the link state of the authentication ONU, and the like are included. The same applies to parameters acquired by the communication parameter monitoring control unit 14.
Further, the communication path alarm notified to the switch control unit 15 includes the MAC address of the ONU 4 located under the communication path where the failure has occurred. The MAC address is a physical address uniquely assigned to the data link layer in order to identify a communication device on the network.

  The switch control unit 15 instructs the switch unit 16 to switch communication paths based on the MAC address availability flag of the ONU entry registered in the authentication database 17. When the switch control unit 15 receives a communication path alarm from the communication parameter monitoring control unit 13 or the communication parameter monitoring control unit 14, the switch control unit 15 receives the MAC address from the authentication database 17 based on the MAC address included in the communication path alarm. Is searched for, and the availability flag of the MAC address is set to invalid (unusable).

  The switch unit 16 learns the MAC address included in the transmission source header of the uplink communication frame from the subscriber terminal 5, and uses the MAC address included in the destination header of the downlink communication frame received from the upper network. A route is selected. Further, the switch unit 16 switches the communication path according to control by the switch control unit 15.

  The authentication database 17 holds information related to the PON interfaces 41 and 42 when communicating with the OLT 1 by simultaneously using the PON interfaces 41 and 42 included in the ONU 4. As shown in FIG. 2, the authentication database 17 includes a MAC address assigned to one PON interface 41 of the ONU 4, a MAC address assigned to the other PON interface 42, and the PON interfaces as shown in FIG. The PON port number of the OLT 1 to which the ONU 4 is connected via 41 and 42 and the availability flag (index) of each MAC address are registered in association with each other.

Next, the operation of the PON system configured as described above will be described with reference to FIG. The operation of the communication parameter monitoring control unit 13 will be described below, but the same applies to the operation of the communication parameter monitoring control unit 14.
In the operation of this PON system, as shown in FIG. 3, first, the communication parameter monitoring control unit 13 first communicates with the predetermined parameter (OLT 1 and the ONU 4 connected under the optical transmission / reception unit 11) from the optical transmission / reception unit 11. (Parameter indicating communication quality) is periodically acquired (step ST1).

Next, the communication parameter monitoring control unit 13 determines whether the acquired parameter is outside the threshold range set by the network administrator (step ST2).
In step ST2, if the communication parameter monitoring control unit 13 determines that the parameter is outside the threshold range, the communication parameter monitoring control unit 13 detects that a failure has occurred in its own communication path, and subordinates the communication path in which the failure has occurred. A communication path alarm including the MAC address of the ONU 4 located at is notified to the switch control unit 15 (step ST3).

  Next, the switch control unit 15 searches the authentication database 17 for an ONU entry including the MAC address based on the MAC address included in the communication path alarm from the communication parameter monitoring control unit 13, and uses the MAC address availability flag. Is set to invalid (step ST4).

  On the other hand, if the communication parameter monitoring control unit 13 determines in step ST3 that the parameter is within the threshold value range, the communication parameter monitoring control unit 13 detects that no failure has occurred in its communication path, and sends it to the switch control unit 15. The communication path alarm is not notified. Thereafter, the sequence proceeds to step ST5.

  Next, the switch control unit 15 controls the switch unit 16 based on the MAC address availability flag of the ONU entry registered in the authentication database 17 (step ST5). Here, when the availability flag of the MAC address of the ONU entry registered in the authentication database 17 is both invalid (unusable), the switch control unit 15 does not control the switch unit 16. On the other hand, when the MAC address availability flag is valid (usable) only, the switch control unit 15 transfers the communication frame to the MAC address for which the availability flag is invalid to the other MAC address. The transfer unit of the communication frame is controlled by the switch unit 16 so as to transfer to the destination. On the other hand, when both the MAC address availability flags are valid, the switch unit 16 is controlled to transfer the communication frame to the two PON interfaces 41 and 42 provided in the ONU 4.

  As described above, according to the first embodiment, the ONU 4 is provided with the plurality of PON interfaces 41 and 42 connected to the OLT 1 through different communication paths, and the OLT 1 is connected to each ONU 4 via the PON interfaces 41 and 42. Communication parameters for acquiring communication quality of a communication path from the optical transmission / reception units 11 and 12 and transmitting / receiving signals between the optical transmission / reception units 11 and 12, and detecting an abnormality of the communication path based on the parameters The monitoring control units 13 and 14, the switch unit 16 for selecting the communication path to be used, and the switch control unit 15 for instructing the switching unit 16 to switch the communication path based on the monitoring results by the communication parameter monitoring control units 13 and 14. Except when a failure occurs in all of the plurality of communication paths between the OLT 1 and the ONU 4. Continue to optical access services to users, even when a failure occurs in the PON section there is an effect that can be provided. Further, as a means for securing a plurality of communication paths between the OLT 1 and the ONU 4, the ONU 4 is provided with a plurality of PON interfaces 41 and 42, so that it is possible for the user at a lower installation cost than the PON system of Patent Document 2. It is possible to provide high quality services.

Embodiment 2. FIG.
In the first embodiment, as shown in FIG. 1, the case where the PON interfaces 41 and 42 (2 ports) of the ONU 4 are connected to different ports (optical transceivers 11 and 12) of the OLT 1 has been described. On the other hand, Embodiment 2 shows a case where the same port is connected.
FIG. 4 is a diagram showing a configuration of a PON system according to Embodiment 2 of the present invention. The PON system according to the second embodiment shown in FIG. 4 is modified so that both the optical branching devices 2 and 3 of the PON system according to the first embodiment shown in FIG. 1 are connected to the optical transceiver 11 of the OLT 1. . Other configurations are the same, and the same reference numerals are given and description thereof is omitted.

  In the configuration shown in FIG. 4, when a branch line failure or a failure of the single PON interface 41 (42) of the ONU 4 occurs between the OLT 1 and the ONU 4, communication can be restored by switching the PON interfaces 41 and 42 of the ONU 4. . The branch line failure refers to a partial communication failure under the PON, such as disconnection of an optical fiber between the optical branching device 2 and the optical branching device 3 or between the optical branching device 2 and the ONU 4.

  As described above, according to the second embodiment, since the PON interfaces 41 and 42 of the ONU 4 are connected to the same port of the OLT 1, a branch line failure occurs between the OLT 1 and the ONU 4, and the single PON interface 41 (42) of the ONU 4 Even if a failure occurs, communication can be restored by switching the PON interfaces 41 and 42 of the ONU 4.

Embodiment 3 FIG.
In the third embodiment, a case will be described in which a communication path is switched from a priority frame when a communication path is switched on one of a plurality of paths in a PON section. The PON system according to the third embodiment is the same as the configuration of the PON system according to the first embodiment shown in FIG. 1, and will be described below with reference to FIG.

  When a trunk failure occurs in the PON section, in the first embodiment, switching of communication paths between a plurality of OLT1-ONUs 4 occurs simultaneously. The trunk line failure means that all terminals connected under the PON cannot continue communication using the PON, such as when the optical transmission / reception units 11 and 12 of the OLT 1 fail or the ONU 4 under the PON erroneously emits light. Refers to communication failure. When communication paths between a plurality of OLT1-ONUs 4 are to be switched as described above, communication data that requires real-time performance such as a voice call is given priority over communication data that does not require real-time performance such as the Internet. It is required to switch.

  Therefore, when the MAC addresses of a plurality of ONUs 4 become invalid, the switch control unit 15 identifies a priority frame from communication frames exchanged between the OLT 1 and the ONU 4, and switches the communication path in order from the priority frame. The switch unit 16 is controlled. At this time, the switch control unit 15 uses a value that can identify the priority of the frame, such as the value of the TOS (Type Of Service) field of the IP packet or the value of the VID (Virtual Local Area Network Identifier). Identify.

  As described above, according to the third embodiment, the priority frame is identified based on the TOS field and the VID value of the communication frame exchanged between the OLT 1 and the ONU 4, and the communication path is switched from the priority frame. Since the switch unit 16 is configured to be controlled, priority frame communication can be maintained even when a trunk failure occurs in the PON section.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1 Station side line terminating equipment (OLT), 2,3 optical branching equipment, 4,4-1 to 4-n Residential terminal equipment (ONU), 5,5-1 to 5-n subscriber terminal, 11,12 optical Transmission / reception unit, 13, 14 Communication parameter monitoring control unit, 15 switch control unit, 16 switch unit, 17 authentication database, 41, 41-1 to 41-n, 42, 42-1 to 42-n PON interface.

Claims (8)

In a PON system comprising a plurality of ONUs and an OLT connected to each ONU,
The ONU is
A plurality of PON interfaces connected to the OLT through different communication paths;
The OLT is
An optical transceiver for transmitting and receiving signals to and from each ONU via the PON interface;
Obtaining a parameter indicating the communication quality of the communication path from the optical transmission and reception unit, and detecting a communication path monitoring control unit based on the parameter;
A switch unit for selecting the communication path to be used;
A PON system comprising: a switch control unit that instructs the switch unit to switch the communication path based on a monitoring result by the communication parameter monitoring control unit. The OLT is
A database in which a physical address assigned to each PON interface is associated with an index indicating whether the physical address can be used;
The switch control unit, when an abnormality is detected by the communication parameter monitoring control unit, sets a corresponding index in the database to be unusable, and controls the switch unit based on the database. Item 2. The PON system according to item 1. 3. The PON system according to claim 1, wherein the ONU duplicates a communication frame from a lower terminal and transfers the communication frame to each of the communication paths via each of the PON interfaces. 4. The PON system according to claim 1, wherein each PON interface of the ONU is connected to an optical transceiver different in the OLT. 5. 4. The PON system according to claim 1, wherein each PON interface of the ONU is connected to the same optical transceiver of the OLT. 5. The switch control unit identifies a priority frame based on a TOS field and a VID value of a communication frame exchanged between the OLT and the ONU, and switches the communication unit to switch the communication path from the priority frame. The PON system according to claim 1, wherein the PON system is controlled. In the ONU connected to the OLT,
An ONU comprising a plurality of PON interfaces connected to the OLT through different communication paths. In OLT connected to multiple ONUs,
An optical transmission / reception unit that transmits / receives signals to / from each ONU via a PON interface connected to the own device through a different communication path;
Obtaining a parameter indicating the communication quality of the communication path from the optical transmission and reception unit, and detecting a communication path monitoring control unit based on the parameter;
A switch unit for selecting the communication path to be used;
An OLT comprising: a switch control unit that instructs the switch unit to switch the communication path based on a monitoring result by the communication parameter monitoring control unit.

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