JP4809867B2 - Optical access termination device - Google Patents

Description

  The present invention relates to an optical access termination device applied to an optical subscriber access network.

  As a network system generally used in the optical subscriber access service, there is a passive optical network (PON). FIG. 1 shows a configuration example of a PON. One optical access terminal device 31, one or more optical network units (ONUs) 32, an optical splitter 38, and an optical fiber 39 that connects them are shown. It is configured using. The ONU 32 is placed, for example, in a subscriber house of an optical subscriber access service, and the optical access termination device 31 is placed in a service provider's building or the like. A card having a function corresponding to the optical access terminal unit 31 in FIG. 1 is referred to as an OSU (Optical Subscriber Unit). However, since the function sharing between the OLT and the OSU can be reconfigured as necessary, these are hereinafter collectively referred to as an optical access termination device.

  In PON, a plurality of ONUs share a band by transmitting upstream signals so that timings do not overlap each other. This is called time division multiple access (TDMA). For downlink signals, signals from the optical access termination device to each ONU are multiplexed and transmitted in different time frames. This is called time division multiplexing (TDM). The configuration and operation of the PON are described in detail in Non-Patent Document 1, for example. PON includes EPON standardized by IEEE 802.3 and G. There is a GPON standardized as the 984 series. The transmission rate of EPON is 1.25 Gbit / s for both uplink and downlink, and the transmission rate of GPON is 1.25 Gbit / s for uplink and 2.5 Gbit / s for downlink (622 Mbit / s, 1.25 Gbit / s). Etc.)

  As shown in FIG. 1, the optical access termination device 31 generally terminates at least an optical transmission / reception means 33 for converting between an electrical signal and an optical signal, and a PON-specific signal format using TDMA. A PON protocol terminator 35 for inserting and extracting PON control protocol information and a service node interface (SNI) 36 for connecting to a service device such as an Ethernet (registered trademark) switch or an IP router. The upstream signal from each ONU 32 is multiplexed into one optical fiber 39 by the optical splitter 38 and transmitted to the optical access termination device 31. In the optical access termination device 31, the upstream signal input from the optical transmission / reception unit 33 is terminated by the PON protocol termination unit 35 and converted into a communication protocol signal (for example, Ethernet (registered trademark) signal) suitable for connection with the service device. It is converted and output to the SNI 36. On the other hand, the downstream signal input from the SNI 36 is input to the optical transmission / reception unit 33 as the downstream signal of the PON via the PON protocol termination unit 35, converted into an optical signal, and then transmitted to each ONU 32 by the optical splitter 38. Branch off.

  In FIG. 1, the number of optical splitters is one, but a configuration in which a plurality of optical splitters are cascade-connected is also common. That is, in order to connect 32 ONUs, one 1-to-32 optical splitter may be used, or (as viewed from the service provider side), a 1-to-4 optical splitter is arranged first and beyond. Alternatively, four 1 to 8 optical splitters may be connected.

  By the way, in order to achieve high reliability of the communication network, the optical access termination device can be connected to a plurality of service devices, and even if one of the service devices has an abnormality, the service is performed by the other service device. Can be used. To this end, it is conceivable to duplicate the service node interface (SNI) of the optical access termination device.

  In order to duplicate the SNI of the PON, for example, it is conceivable to arrange an electrical or optical switch before the SNI and perform 1 + 1 switching or 1: 1 switching. FIG. 2 shows an example of this configuration. In the optical access termination device 41, a 1 × 2 (one input and two output) optical switch (or distributor) 34A is arranged on the upstream signal path between the PON protocol termination means 35 and the SNI 36A and SNI 36B. A × 2 optical switch 34B (or distributor) is arranged in the downstream signal path between the PON protocol termination means 35 and the SNI 36A and SNI 36B so that one of the two SNIs 36A and 36B can be selected. Yes.

  The optical access termination device 41 includes SNI link monitoring means 37, and monitors normality / abnormality of communication related to the corresponding SNIs 36A and 36B. The normality / abnormality of communication related to the SNI means normality / abnormality of a service device connected to the opposite side via the SNI, normality / abnormality of a transmission path between the SNI and the service device, and the like. For example, the presence or absence of an SNI input signal or ITU-T G. Normality / abnormality of communication related to the SNI is distinguished by an Ethernet (registered trademark) OAM (Operation And Maintenance) signal defined in 1731.

SNI 36A and SNI 36B have one (for example, SNI 36A) as the active system and the other (SNI 36B) as the standby system. Only when the communication related to the SNI 36A is abnormal and the communication related to the SNI 36B is normal, the PON protocol termination means inputs and outputs signals to and from the standby SNI 36B. The optical switches 34A and 34B may be switched.
Technology Basic Course “GE-PON Technology 1st PON”, NTT Technical Journal, Vol. 17, no. 8, pp. 71-74, 2005

In order to achieve the above object, an optical access termination apparatus according to the present invention terminates a plurality of optical transmission / reception means for converting electrical signals and optical signals from each other, a PON-specific signal format using TDMA, and PON control protocol information. A link for monitoring normality / abnormality of communication related to the plurality of service node interfaces in an optical access termination apparatus comprising two PON protocol termination means for inserting and extracting PON and a plurality of service node interfaces for connecting to a higher level network A bandwidth allocation unit that allocates a bandwidth to one or more optical network units connected to each of the plurality of optical transmission / reception units, and between the plurality of optical transmission / reception units and the two PON protocol termination units . a first electric circuit arranged upstream signal path, the band allocation means, before When communication related to a plurality of service node interfaces is normal, the optical network unit connected to the optical transmission / reception means corresponding to the PON protocol termination means shares the bandwidth that can be processed by the PON protocol termination means, When a bandwidth is allocated to the optical network unit and communication related to any of the plurality of service node interfaces becomes abnormal, the bandwidth that can be processed by the PON protocol terminator corresponding to the normal side corresponds to the abnormal side. A bandwidth is allocated to the optical network unit so that the optical network unit connected to the optical transmission / reception means and the optical network unit connected to the optical transmission / reception means corresponding to the normal side share, and the optical transmission / reception corresponding to the abnormal side A band of one or more optical network units connected to the means And assigned to the continuous time domain, the bandwidth of one or more optical network units connected to the optical transmitting and receiving means corresponding to the normal side, assigned to another continuous time domain, the first electrical circuit, said When communication related to a plurality of service node interfaces is normal, an upstream signal input from each optical transmission / reception unit is output to the PON protocol termination unit corresponding to the optical transmission / reception unit, and any of the plurality of service node interfaces is output. When communication related to the above becomes abnormal, either the upstream signal input from the optical transmission / reception means corresponding to the abnormal side or the upstream signal input from the optical transmission / reception means corresponding to the normal side is dynamically changed. Select and output to the PON protocol terminator corresponding to the normal side, and to the abnormal side based on the band allocation by the band allocation unit In the band allocated to the optical network unit connected to the corresponding optical transmission / reception means, the upstream signal input from the optical transmission / reception means corresponding to the abnormal side is selected, and the optical signal connected to the optical transmission / reception means corresponding to the normal side is selected. In the band allocated to the network unit, an uplink signal input from the optical transmission / reception unit corresponding to the normal side is selected and output to the PON protocol termination unit corresponding to the normal side .

  The present invention has been made in view of such problems, and an object of the present invention is to multiplex service node interfaces (SNIs) for connection to service devices and when there is no abnormality in communication. Another object of the present invention is to provide an optical access termination device that can efficiently use a service node interface (SNI).

  In order to achieve the above object, an optical access termination apparatus according to the present invention terminates a plurality of optical transmission / reception means for converting electrical signals and optical signals from each other, a PON-specific signal format using TDMA, and PON control protocol information. A link for monitoring normality / abnormality of communication related to a plurality of service node interfaces in an optical access termination apparatus comprising a plurality of PON protocol termination means for inserting and extracting a plurality of PON protocol termination means and a plurality of service node interfaces for connecting to a higher level network Monitoring means, and a first electric circuit is disposed in an upstream signal path between the plurality of optical transmission / reception means and the plurality of PON protocol termination means, and the first electric circuit is connected to the plurality of service node interfaces. When such communication is normal, the upstream signal input from each optical transmission / reception means Output to the PON protocol termination means corresponding to the communication means, and when communication related to any of the plurality of service node interfaces becomes abnormal, an upstream signal input from the optical transmission / reception means corresponding to the abnormal side; One of the uplink signals input from the optical transmission / reception means corresponding to the normal side is dynamically selected and output to the PON protocol termination means corresponding to the normal side.

  Further, the optical access termination device of the present invention arranges a second electrical circuit in a downstream signal path between the plurality of optical transmission / reception means and the plurality of PON protocol termination means, and the second electrical circuit is When communication related to a plurality of service node interfaces is normal, a downlink signal input from each PON protocol termination unit is output to the optical transmission / reception unit corresponding to the PON protocol termination unit, and the plurality of service node interfaces When any of the communication is abnormal, it is preferable that a downlink signal input from the PON protocol termination unit corresponding to the normal side is branched and output to the plurality of optical transmission / reception units.

  Further, the optical access termination apparatus of the present invention comprises a plurality of groups of optical transmission / reception means, each group consisting of a plurality of optical transmission / reception means, instead of the plurality of optical transmission / reception means, Electrical coupling means for coupling upstream signals of each group is disposed between the first electrical circuit, and downstream signals of each group are disposed between the optical transmission / reception means of each group and the second electrical circuit. It is preferable that an electrical branching means for branching is arranged.

  The first and second electric circuits are multi-input multi-output electric circuits that select a plurality of branching means for branching a signal input from the input side and signals from the plurality of branching means. It is preferable to provide a plurality of selection means for outputting.

  Further, the first and second electric circuits are electric circuits having a plurality of inputs and a plurality of outputs, and a plurality of buffers for accumulating signals input from the input side and signals from the plurality of buffers are multiplexed. It is preferable to provide a plurality of multiplexing means for outputting.

The optical access termination device of the present invention multiplexes the service node interface (SNI) for connection to the service device, and performs communication using the normal SNI when there is an abnormality in communication. When there is no abnormality, communication is performed using all of the multiplexed SNI, so that the SNI can be used efficiently.
In addition, the optical access termination apparatus of the present invention can be used without changing the standardized specifications for PON optical transmission and protocol.

Embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 3 shows the configuration of an optical access termination device according to the first embodiment of the present invention and an optical access network to which this optical access termination device is applied. The optical access termination device 1 includes two optical transmission / reception means 3A and 3B for converting electrical signals and optical signals, two PON protocol termination means 5A and 5B for inserting and extracting PON control protocol information, and Ethernet (registration). 2) service node interfaces (SNI) 6A and 6B for connecting to a higher level network including switches and IP routers, SNI link monitoring means 7 for monitoring SNI 6A and 6B, and PON protocol termination means 5A and 5B. The bandwidth allocating means 8 for allocating the bandwidth to the connected optical network units (ONU) 2 ₁ to 2 _n (n is a natural number) and two 2 × 2 (2 inputs 2 outputs) electric circuits 4U, 4D Consists of As shown in FIG. 3, among ONUs 2 ₁ to 2 _n , ONUs 2 ₁ to 2 _m are connected to the optical access terminator 1 via optical transmission / reception means 3A, and ONUs 2 _{m + 1} to 2 _n are optical transmission / receptions. It is connected to the optical access termination device 1 through the means 3B (m is a natural number smaller than n).

  The SNI link monitoring means 7 monitors normality / abnormality of communication related to the corresponding SNI 6A, 6B. For example, the presence / absence of an input signal to SNI 6A, 6B, or ITU-T G. Normal / abnormal is distinguished by an Ethernet (registered trademark) OAM (Operation And Maintenance) signal defined in 1731.

  As shown in FIG. 3, the 2 × 2 (2-input 2-output) electric circuit 4U is connected to the upstream signal path between the two optical transmission / reception units 3A and 3B and the two PON protocol termination units 5A and 5B. Be placed. In accordance with the monitoring information of the SNI link monitoring means 7, the 2 × 2 electric circuit 4U detects the upstream signal input from the optical transmission / reception means 3A when the communication related to both SNIs 6A and 6B is detected as normal. It outputs to the PON protocol termination means 5A, and outputs the upstream signal input from the optical transmission / reception means 3B to the PON protocol termination means 5B. When communication related to either SNI 6A or 6B (for example, SNI 6A) indicates an abnormality, the upstream signal input from the optical transmission / reception means 3A corresponding to the abnormal side and the optical transmission / reception means 3B corresponding to the normal side Is dynamically selected and output toward the PON protocol terminator 5B corresponding to the normal side.

  As shown in FIG. 3, the 2 × 2 electric circuit 4U can be configured by two branching units 9A and 9B and two selection units 10A and 10B. The branching unit 9A branches the upstream signal input from the optical transmission / reception unit 3A into two, and the branching unit 9B branches the upstream signal input from the optical transmission / reception unit 3B into two. The selection unit 10A corresponds to the PON protocol termination unit 5A, and is configured to be able to select either an upstream signal input from the optical transmission / reception unit 3A or the optical transmission / reception unit 3B. The selection unit 10B includes the PON protocol termination unit 5A. It corresponds to the means 5B and is configured to be able to select either an upstream signal input from the optical transmission / reception means 3A or the optical transmission / reception means 3B.

  As shown in FIG. 3, the 2 × 2 (2-input 2-output) electric circuit 4D is connected to the downstream signal path between the two optical transmission / reception units 3A and 3B and the two PON protocol termination units 5A and 5B. Be placed. In accordance with the monitoring information of the SNI link monitoring means 7, the 2 × 2 electric circuit 4D detects the downstream signal input from the PON protocol termination means 5A when it detects that the communication related to both SNIs 6A and 6B is normal. The optical signal is output to the optical transmission / reception means 3A, and the downstream signal input from the PON protocol termination means 5B is output to the optical transmission / reception means 3B. When the communication related to either SNI 6A or 6B (for example, SNI 6A) shows an abnormality, the optical transmission / reception means 3A and the optical transmission / reception means receive the downstream signal input from the PON protocol termination means 5B corresponding to the normal side. Branch to 3B and output.

  As shown in FIG. 3, the 2 × 2 electric circuit 4D can be configured by two branching units 11A and 11B and two selection units 12A and 12B. The branching unit 11A branches the downlink signal input from the PON protocol termination unit 5A into two, and the branching unit 11B branches the downlink signal input from the PON protocol termination unit 5B into two. The selection unit 12A corresponds to the optical transmission / reception unit 3A, and is configured to be able to select either a downstream signal input from the PON protocol termination unit 5A or the PON protocol termination unit 5B. The selection unit 12B It corresponds to the means 3B, and is configured to be able to select either a downstream signal input from the PON protocol termination means 5A or the PON protocol termination means 5B.

  By configuring the optical access termination device in this way, SNI duplication can be realized, and both SNIs can be used for communication even when communication related to the two SNIs is normal.

  Note that the maximum number of ONUs that can be handled by a single optical transmission / reception means is limited to the loss of the optical splitter that increases with an increase in the number of branches. When the transmission speed is about 1.25 Gbit / s, 16 to 64 It will be about. Therefore, in this embodiment, the maximum number m of ONUs connected to the optical transmission / reception unit 3A is, for example, 16 to 64, and the maximum number n of ONUs connected to the optical transmission / reception unit 3A and the optical transmission / reception unit 3B is For example, it is 32-128.

As shown in FIG. 3, the optical access termination apparatus 1 further includes a common bandwidth allocation unit 8 related to both the PON protocol termination units 5A and 5B.
The bandwidth allocating unit 8 determines the bandwidth that can be processed by the PON protocol termination unit 5A when the communication related to the SNIs 6A and 6B is normal, and the ONU connected to the optical transmission / reception unit 3A corresponding to the PON protocol termination unit 5A. A band is allocated to the ONUs 2 ₁ to 2 _m so that 2 _{1 to} 2 _m are shared, and a band that can be processed by the PON protocol termination unit 5B is connected to the optical transmission / reception unit 3B corresponding to the PON protocol termination unit 5B. A bandwidth is allocated to ONU 2 _{m + 1} to 2 _n so that ONU 2 _{m + 1 to} 2 _n share the same. Further, when the communication related to either SNI 6A or 6B (for example, SNI 6A) becomes abnormal, the bandwidth that can be processed by the PON protocol terminator 5B corresponding to the normal side is transmitted / received corresponding to the abnormal side. and ONU ₂ 1 to 2 _m, which is connected to means 3A, to be shared by the ONU _{2 m} + 1 ~2 _n connected to the light receiving means 3B corresponding to the normal side, allocates a bandwidth to the _ONU 2 1 to 2 _n .

FIG. 4 is a diagram showing a bandwidth allocation method when the ONUs 2 ₁ to 2 _n perform communication in the configuration of FIG. In FIG. 4, ONU 2 ₁ to 2 _m are represented as ONU ₁ to _m , and ONU 2 _{m + 1} to 2 _n are represented as ONU _{m + 1} to _n . LLID (Logical Link IDentifier) in FIG. 4 is an identifier of a logical link, and corresponds to the LLID defined in the standard in the case of GE-PON standardized by IEEE802.3. The reference numerals in the figure indicate the case where ONUs and LLIDs have a one-to-one correspondence. In some cases, one ONU uses a plurality of logical link identifiers. In this case, a method of performing bandwidth allocation not for each ONU but for each LLID is also common, and therefore, the following description will be made using LLID.

  FIG. 4 (1) is a diagram showing an example of bandwidth allocation of the uplink signal processed by the PON protocol terminator 5A when the communication related to the SNIs 6A and 6B is normal, and FIG. 4 (2) is a diagram showing the SNI 6A. , 6B is a diagram showing an example of bandwidth allocation of the upstream signal processed by the PON protocol termination unit 5B when the communication related to both is normal. The PON protocol termination unit 5A transmits, to LLIDs 1 to m, a control signal that specifies the uplink signal transmission time so that the uplink signals do not overlap with each other in time. In the case of GE-PON standardized by IEEE802.3, this is specified by a control frame called a Gate frame. Similarly, the PON protocol termination unit 5B transmits a control signal for designating the uplink signal transmission time to the LLIDs m + 1 to n + 1 so that the uplink signals do not overlap with each other in time. When the communication related to the SNIs 6A and 6B is both normal, as shown in FIGS. 4 (1) and (2), the time between the upstream signals of LLID 1 to m and the upstream signals of LLID m + 1 to n There is no need to consider the overlap. The grant period is a period of repeated band allocation, and as shown in FIGS. 4A and 4B, the allocation time to each LLID may be changed for each grant period (dynamic band allocation method). ).

  FIG. 4 (3) is a diagram showing an example of bandwidth allocation of the uplink signal processed by the PON protocol termination unit 5B when the communication related to the SNI 6A is abnormal. When the communication related to the SNI 6A is abnormal, the PON protocol termination unit 5B transmits a control signal designating the upstream signal transmission time of all LLIDs (1 to m and m + 1 to n). Further, the 2 × 2 electric circuit 4U dynamically switches the uplink signals input from the optical transmission / reception means 3A and 3B based on the uplink signal transmission time specified here. FIG. 4 (4) is a diagram showing a signal selection state of the 2 × 2 electric circuit 4U. Specifically, the 2 × 2 electric circuit 4U has the LLID 1 as shown in FIG. 4 (4). In the time (band) assigned to ~ m, it operates to select the upstream signal input from the optical transmission / reception means 3A, and from the optical transmission / reception means 3B in the time (band) assigned to LLID m + 1 to n. Operate to select the upstream signal to be transmitted. That is, FIG. 4 (4) can be used as a signal for driving the selection means inside the 2 × 2 electric circuit 4U as it is.

  At this time, as shown in FIGS. 4 (3) and (4), when the communication related to either SNI 6A or 6B (for example, SNI 6A) is abnormal, the bandwidth of the uplink signal of LLID 1 to m is set. By assigning to the continuous time domain and assigning the upstream signal band of LLID m + 1 to n to another continuous time domain, the number of times of switching the 2 × 2 electric circuit U can be reduced. That is, time slots are allocated so that the time is not complicated, such that the upstream signals of LLID 1 to m are the first half of the grant period, and the upstream signals of LLID m + 1 to n are the second half of the grant period.

  The same may be done when the communication related to SNI 6B is abnormal. FIG. 4 (5) is a diagram showing an example of bandwidth allocation of the upstream signal processed by the PON protocol termination unit 5A when the communication related to the SNI 6B is abnormal, and FIG. 4 (6) is a 2 × 2 electric circuit. It is the figure which showed 4D signal selection state.

  Since the distance between the optical access termination device and each ONU differs for each ONU, this causes a propagation delay difference. The bandwidth allocation function of the PON normally specifies the upstream signal transmission time of each ONU by subtracting this propagation delay difference so that the upstream signal arrival time does not overlap the optical access termination device. This function is a basic function deployed in all PONs, and is also necessary when performing the bandwidth allocation of the present embodiment described above.

(Second Embodiment)
FIG. 5 shows the configuration of an optical access termination device according to the second embodiment of the present invention and an optical access network to which this optical access termination device is applied. In the optical access termination device 21 according to the second embodiment, instead of the two optical transmission / reception units 3A and 3B in the first embodiment, two groups of optical transmission / reception units 3A ₁ , 3A ₂ , 3A ₃ ,. 3A _k (hereinafter referred to as group A), 3B ₁ , 3B ₂ , 3B ₃ ,... 3B _k (hereinafter referred to as group B) are arranged (k is a natural number). The ONUs 2 _{1 to} 2 _m are respectively connected to any one of the optical transmission / reception means of the group A, and the ONUs 2 _{m + 1} to 2 _n are respectively connected to any one of the optical transmission / reception means of the group B. Between the × 2 electrical circuit 4U, two electrical coupling means 13A and 13B for coupling the upstream signals of the groups A and B are arranged, and between the optical transmission / reception means and the 2 × 2 electrical circuit 4D, the group A, Two electric branching means 14A and 14B for branching the downstream signals of B are arranged.

  That is, in the second embodiment, a part of the upstream / downstream signal coupled / branched by the optical splitter in the first embodiment is performed by the electrical coupling / branching means in the optical access termination device. The optical transmission section of the PON is generally one-core bi-directional, and the optical splitter can combine the combination of the upstream signal and the branch of the downstream signal. However, the electrical signal in the optical access termination device is different for upstream and downstream. In order to propagate the path, the electrical coupling means and the electrical branching means are separated.

By the way, the maximum number of ONUs that can be handled by a single optical transmission / reception means is limited to the loss of the optical splitter that increases as the number of branches increases, and when the transmission rate is about 1.25 Gbit / s, 16 to 64. I mentioned earlier that this would be a degree. In the case of this embodiment, for example, four optical transmission / reception means of group A (3A ₁ , 3A ₂ , 3A ₃ , 3A ₄ ) are arranged, and four optical transmission / reception means of group B (3B ₁ , 3B ₂ , 3B ₃ , 3B ₄ ), the maximum number m of ONUs connected to the optical transmission / reception means of group A is 64 to 256, and the maximum number n of ONUs connected to the optical transmission / reception means of group A and group B Becomes 128-512.

  By using such a configuration, the number of shared 2 × 2 electric circuits U and 2 × 2 electric circuits D can be increased without being limited by the number of ONUs that can be connected to a single optical transmission / reception means. That is, if one user uses one ONU, the cost per user can be reduced.

(Third embodiment)
Next, an optical access termination apparatus according to a third embodiment of the present invention will be described. In the optical access termination device according to the third embodiment, the configuration of the 2 × 2 electrical circuit is different from the configuration of the 2 × 2 electrical circuit in the first and second embodiments. FIG. 6 shows a configuration example of the 2 × 2 electric circuit 24U according to the third embodiment arranged in the upstream signal path, and FIG. 7 shows 2 × 2 electric circuit according to the third embodiment arranged in the downstream signal path. The structural example of the circuit 24D is shown. These 2 × 2 electric circuits temporarily buffer the input signal for each frame, and then output each frame to one of the multiplexing means according to the header information of the frame. For header information indicating the output destination, LLID may be used in the case of PON standardized by IEEE.

  As shown in FIG. 6, the 2 × 2 electric circuit 24U includes two input buffers 25A and 25B and two output side multiplexing means 26A and 26B. When the communication related to the SNIs 6A and 6B is normal, the frame of the input buffer 25A is always output to the multiplexing unit 26A, and the frame of the input buffer 25B is always output to the multiplexing unit 26B. When the communication related to the SNI 6A is abnormal, both the frame of the input buffer 25A and the frame of the input buffer 25B are output to the multiplexing unit 26B. When the communication related to the SNI 6B is abnormal, both the frame of the input buffer 25A and the frame of the input buffer 25B are output to the multiplexing unit 26A.

  As shown in FIG. 7, the 2 × 2 electric circuit 24D is similarly configured and includes two input buffers 27A and 27B and two output side multiplexing means 28A and 28B.

  If the communication related to SNI 6A (or SNI 6B) is abnormal when the 2 × 2 electric circuit having the above-described configuration is used, the frame is once stored in the input buffer, so that the 2 × 2 electric circuit (24U or 24D), for example, it is only necessary to read out the frame to two multiplexing means alternately so that the timing does not overlap, and in accordance with the PON time slot allocation as described with reference to (4) and (6) of FIG. There is no need to perform selective control.

In the above-described embodiment, the case where the service node interface (SNI) related to the connection to the service device is duplicated has been described. However, the present invention is not limited to the case where the SNI is duplicated. This also applies to the case where two or more SNIs are provided and multiplexed.
For example, with three SNIs, the first electrical circuit is a 2 × 3 (2 inputs 3 outputs) electrical circuit, the second electrical circuit is a 3 × 2 (3 inputs 2 outputs) electrical circuit, and the SNI is tripled This also applies to the case where the change is made.

As described above, the optical access termination device of the present invention multiplexes the service node interface (SNI) related to the connection to the service device and communicates using the normal SNI when there is an abnormality in communication. If there is no abnormality in communication, communication is performed using the multiplexed SNI, so that the SNI can be used efficiently (100%).
In addition, the optical access termination apparatus of the present invention can be used without changing the standardized specifications for PON optical transmission and protocol.

It is a figure which shows the structural example of PON. It is a figure which shows the structural example of PON which duplexed SNI. 1 is a diagram illustrating an optical access termination device according to a first embodiment of the present invention and a configuration of an optical access network to which the optical access termination device is applied. It is a figure which shows the band allocation method in case ONU communicates in the structure of FIG. It is a figure which shows the structure of the optical access termination device which concerns on the 2nd Embodiment of this invention, and the optical access network to which this optical access termination device is applied. It is a figure which shows the other structural example of the 2 * 2 electric circuit arrange | positioned at an upstream signal path | route. It is a figure which shows the other structural example of the 2 * 2 electric circuit arrange | positioned at a downstream signal path | route.

Explanation of symbols

1,21,31,41 optical access termination device 2 ₁ ~2 _n, 32 ONU
3A, 3B, 3A _{1 to} 3A _n , 3B _{1 to} 3B _n , 33 Optical transmission / reception means 4U, 4D, 24U, 24D 2 × 2 electric circuit 5A, 5B, 35 PON protocol termination means 6A, 6B, 36, 36A, 36B SNI
7, 37 SNI link monitoring means 8 Bandwidth allocation means 9A, 9B, 11A, 11B Branch means 10A, 10B, 12A, 12B Selection means 13A, 13B Electrical coupling means 14A, 14B Electrical branch means 25A, 25B, 27A, 27B Input buffer 26A, 26B, 28A, 28B Multiplexing means 34A, 34B Switch 38 Optical splitter 39 Optical fiber

Claims (5)

Optical access comprising a plurality of optical transmission / reception means for converting electrical signals and optical signals to each other, two PON protocol termination means for inserting and extracting PON control protocol information, and a plurality of service node interfaces for connection to a higher level network In the termination equipment,
Link monitoring means for monitoring normality / abnormality of communication related to the plurality of service node interfaces ;
Band allocation means for allocating a band to one or more optical network units connected to each of the plurality of optical transmission / reception means ,
A first electrical circuit is disposed in an upstream signal path between the plurality of optical transmission / reception means and the two PON protocol termination means;
The bandwidth allocating means includes
When communication related to the plurality of service node interfaces is normal, the optical network unit connected to the optical transmission / reception means corresponding to the PON protocol termination means shares the bandwidth that can be processed by the PON protocol termination means. Allocate bandwidth to the optical network unit,
When communication related to any of the plurality of service node interfaces becomes abnormal, a band that can be processed by the PON protocol termination unit corresponding to the normal side is connected to the optical transmission / reception unit corresponding to the abnormal side. One or more bandwidths are allocated to the optical network unit so that the network unit and the optical network unit connected to the optical transmission / reception means corresponding to the normal side are shared, and one or more connected to the optical transmission / reception means corresponding to the abnormal side The bandwidth of one optical network unit is assigned to a continuous time domain, and the bandwidth of one or more optical network units connected to the optical transmission / reception means corresponding to the normal side is assigned to another continuous time domain,
The first electric circuit is:
When communication related to the plurality of service node interfaces is normal, an upstream signal input from each optical transmission / reception unit is output to the PON protocol termination unit corresponding to the optical transmission / reception unit,
When communication related to any of the plurality of service node interfaces becomes abnormal, the uplink signal input from the optical transmission / reception means corresponding to the abnormal side and the uplink signal input from the optical transmission / reception means corresponding to the normal side One of the signals is dynamically selected and output to the PON protocol termination unit corresponding to the normal side, and connected to the optical transmission / reception unit corresponding to the abnormal side based on the band allocation by the band allocation unit In the band allocated to the optical network unit, the upstream signal input from the optical transmission / reception means corresponding to the abnormal side is selected, and in the band allocated to the optical network unit connected to the optical transmission / reception means corresponding to the normal side, The PON protocol terminator corresponding to the normal side by selecting the upstream signal input from the optical transmitting / receiving means corresponding to the normal side Optical access termination device according to claim <br/> be output. The optical access termination device according to claim 1 ,
A second electrical circuit is disposed in a downstream signal path between the plurality of optical transmission / reception means and the plurality of two PON protocol termination means;
The second electric circuit is:
When the communication related to the plurality of service node interfaces is normal, the downstream signal input from each PON protocol termination unit is output to the optical transmission / reception unit corresponding to the PON protocol termination unit,
When communication related to any of the plurality of service node interfaces becomes abnormal, the downlink signal input from the PON protocol termination unit corresponding to the normal side is branched and output to the plurality of optical transmission / reception units An optical access termination device. The optical access termination device according to claim 1 or 2 ,
Instead of the plurality of optical transmission / reception means, one group comprises a plurality of groups of optical transmission / reception means consisting of a plurality of light transmission / reception means
Electrical coupling means for coupling the upstream signal of each group is arranged between the optical transmission / reception means of each group and the first electric circuit, and between the optical transmission / reception means of each group and the second electric circuit. And an optical branching means for branching the downlink signal of each group. The optical access termination device according to claim 2 ,
The first and second electric circuits are:
A multi-input multi-output electric circuit, comprising: a plurality of branch means for branching a signal input from the input side; and a plurality of selection means for selecting and outputting signals from the plurality of branch means. An optical access termination device. The optical access termination device according to claim 2 ,
The first and second electric circuits are:
A multi-input multi-output electric circuit, comprising: a plurality of buffers for accumulating signals input from the input side; and a plurality of multiplexing means for multiplexing and outputting signals from the plurality of buffers. Optical access terminator.

Images