JP2015211225A - Slave station device, master station device, control device, optical communication system, and band allocation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ONU capable of reducing a buffer memory capacity of the ONU.SOLUTION: An ONU10-1, connected with an optical communication path to an OLT1, to which a communication band in an upstream direction, which is a direction heading for the OLT1, is allocated, includes: a communication monitoring unit 111 for monitoring an amount of transmission data transmitted to the OLT1; and a band request unit 113 for calculating a report band, which is a request band for requesting to the OLT1 on the basis of an amount of transmission data and reporting the report band to the OLT1.

Description

  The present invention relates to a slave station device, a master station device, a control device, an optical communication system, and a bandwidth allocation control method.

  In an optical access system such as a PON (Passive Optical Network) system, a plurality of ONUs (Optical Network Units) are connected to an OLT (Optical Line Terminal) via an optical multiplexer / demultiplexer such as an optical splitter. Take.

  In the PON system, a wavelength division multiplexing (WDM) method using different wavelengths is generally used for downlink communication from the OLT to the ONU and uplink communication from the ONU to the OLT.

  In the PON system, since one optical fiber is shared by a plurality of ONUs, a plurality of pieces of data (time division multiplexing (TDM)) are used in downstream communication from the OLT to the ONUs (Time Division Multiplexing). (Downlink data) are multiplexed and transmitted so that they do not overlap in time. In downlink communication, all ONUs connected to the same optical splitter receive the same data, and each ONU extracts only data corresponding to itself.

  On the other hand, in uplink communication from the ONU to the OLT, data (uplink data) transmitted from a plurality of ONUs are multiplexed by the optical splitter. In the PON system, the data transmission start time and the data transmission amount of each ONU are controlled by using TDMA for uplink communication so that no collision occurs on the transmission path after multiplexing. Thus, uplink data is multiplexed while avoiding collision on the transmission path.

  In the conventional bandwidth allocation control method, when transmission waiting data is accumulated in the ONU, the ONU notifies the OLT of the requested bandwidth. Based on the notification of the requested bandwidth from each ONU, the OLT arbitrates the total bandwidth allocated to each ONU so that it falls within the usable upstream bandwidth, and transmits the data transmission start time and data transmission of each ONU. Determine the amount. Then, the OLT notifies the ONU of the determined data transmission start time and data transmission amount.

  Conventionally, as a bandwidth allocation control method, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation G. 983.4 defines an SR (Status Reporting) method and an NSR (Non-Status Reporting) method. Patent Document 1 below discloses a method in which the OLT includes means for analyzing the change amount of the requested bandwidth notified from the ONU, and the bandwidth allocation control method is switched based on the analysis result. In the method described in Patent Document 1 below, when it is determined that there is an increasing tendency with respect to the required amount of change in the bandwidth, the bandwidth allocation control method is switched to the SR method. Further, when it is determined that the required bandwidth change amount is decreasing or no change, the bandwidth allocation control method is switched to the NSR method.

  Patent Document 2 below discloses a bandwidth control device that detects a TCP (Transmission Control Protocol) connection establishment request signal or a connection disconnection signal by a communication monitoring means, and switches a bandwidth allocation control method based on the detection result. It is disclosed.

JP 2010-199861 A JP 2012-257163 A

  In a concentrator network such as an optical access system typified by a PON system, a buffer memory for temporarily storing data is necessary to compensate for a difference in communication speed between different devices. For this reason, there is a problem that the capacity of the buffer memory increases as the communication speed increases. There is also a problem that power consumption increases with an increase in buffer memory.

  The OLT needs to temporarily store upstream data transmitted from the connected ONU in a buffer memory inside the OLT. The ONU needs to temporarily store upstream data transmitted from network connection devices such as HGW (Home Gate Way) in a buffer memory provided in the ONU.

  Conventionally, in the bandwidth allocation control method used in the PON system, the data transmission start time and the data transmission amount of uplink communication of each ONU are performed by the dynamic bandwidth allocation (DBA) function implemented in the OLT. Is controlling. The ONU transmits uplink data according to the data transmission start time and the data transmission amount notified from the OLT. Even when the requested bandwidth notified by the ONU is the same, the data transmission start time and the data transmission amount allocated to each ONU differ depending on the bandwidth allocation control method implemented in the OLT. For this reason, the capacity of the buffer memory required in the ONU depends on the bandwidth allocation control method. Therefore, the ONU has a problem that it is difficult to reduce the capacity of the buffer memory because the capacity of the buffer memory capable of supporting a plurality of bandwidth allocation control methods is secured.

  The technologies described in Patent Documents 1 and 2 are technologies for switching the OLT bandwidth allocation control method, and are aimed at improving the bandwidth utilization efficiency or reducing the capacity of the buffer memory provided in the OLT. For this reason, the capacity of the ONU buffer memory cannot be reduced.

  The present invention has been made in view of the above, and a slave station device, a master station device, a control device, an optical communication system, and bandwidth allocation control capable of reducing the capacity of a buffer memory of a slave station device (ONU) The purpose is to obtain a method.

  In order to solve the above-described problems and achieve the object, the present invention is connected to a master station device through an optical communication path, and transmits an upstream communication band to the master station device from the master station device. A slave station device to be allocated, a communication monitoring unit that monitors the amount of transmission data transmitted to the parent station device, and a notification bandwidth that is a request bandwidth requested to the parent station device based on the amount of transmission data And a bandwidth request unit for notifying the master station device of the notification bandwidth.

  According to the present invention, it is possible to reduce the capacity of the buffer memory of the slave station apparatus (ONU).

FIG. 1 is a diagram showing a configuration example of a PON system according to the present invention. FIG. 2 is a diagram illustrating an example of message exchange regarding bandwidth allocation between the OLT and the ONU. FIG. 3 is a diagram illustrating an example of a required bandwidth determination processing procedure.

  Embodiments of a slave station device, a master station device, a control device, an optical communication system, and a bandwidth allocation control method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a configuration example of a PON (Passive Optical Network) system (optical communication system) according to the present invention. As shown in FIG. 1, the PON system according to the present embodiment operates as a station side optical communication device (also referred to as “Optical Line Terminal”, hereinafter referred to as “OLT”) that operates as a master station device, and as a slave station device. A plurality of user-side optical communication devices (also referred to as “Optical Network Unit”, hereinafter referred to as “ONU”).

  The OLT 1 and the ONUs 10-1 to 10-3 are connected by an optical fiber (optical communication path) 30 via a splitter 40. The splitter 40 branches the trunk optical fiber 30 connected to the OLT 1 into the number of ONUs 10-1 to 10-3. The ONU 10-1 is connected to the network device 20-1 and the network device 20-2. The network devices 20-1 and 20-2 are, for example, HGW (Home Gate Way). In this example, three ONUs are shown, but the number of ONUs is not limited to this, and any number may be used. In this example, the number of network devices connected to the ONU 10-1 is two, but the number of network devices connected to the ONU 10-1 is not limited to this and may be any number.

  The OLT 1 includes a PON control unit 2 (master station control unit) that performs processing on the OLT side based on the PON protocol, and an upstream buffer 3 that is a buffer for storing upstream data received from the ONUs 10-1 to 10-3. A downlink buffer 4 that is a buffer for storing downlink data to be transmitted to the ONUs 10-1 to 10-3 received from the upper network (CoreNetwork) 50, an optical transceiver 5 that performs optical signal transmission / reception processing, and an uplink And a WDM (Wavelength Division Multiplexing) coupler (WDM) 6 that wavelength-multiplexes data and downlink data. The PON control unit 2 includes a bandwidth allocation unit 21. If wavelength multiplexing is not performed, the WDM coupler 6 may not be provided.

  The PON protocol is a control protocol used in a MAC (Media Access Control) layer, which is a sub-layer of Layer 2, and is, for example, MPCP defined by IEEE (Institute of Electrical and Electronic Engineers). (Multi-point Control Protocol) and OAM (Operation Administration and Maintenance).

  The ONU 10-1 is a PON control unit 11 (slave station control unit) (control device) that performs processing on the ONU side based on the PON protocol, and a buffer memory for storing transmission data (upstream data) to the OLT 1 A certain upstream buffer 12, a downstream buffer 13, which is a buffer memory for storing received data (downstream data) from the OLT 1, an optical transmitter / receiver 14, and a WDM coupler that wavelength-multiplexes upstream and downstream optical signals. WDM) 15. If wavelength multiplexing is not performed, the WDM coupler 15 may not be provided. The PON control unit 11 includes a communication monitoring unit 111, a communication amount comparison unit 112, and a bandwidth request unit 113. Thereafter, when individually specifying ONUs, they are described with branch numbers, such as ONU10-1, and shown as ONUs 10-1 to 10-3 in general without distinguishing between ONUs 10-1 to 10-3. In this case, it is described as ONU10.

  The PON protocol is a control protocol used in a MAC (Media Access Control) layer, which is a sub-layer of Layer 2, and is, for example, MPCP (Multi-point Control Protocol) defined by IEEE, OAM (Operation Administration and Maintenance). The PON protocol applied to the present invention is not limited to these examples and may be any type.

  In the following description, the PON system will be described as an example. However, the present invention is not limited to the PON system, and can be applied to any optical communication system in which a master station device allocates a band to a slave station device. Furthermore, the present invention can be similarly applied to a communication system other than the optical communication system as long as the master station apparatus allocates a band to the slave station apparatus.

  Next, the overall operation of the OLT 1 and the ONUs 10-1 to 10-3 according to the present embodiment will be described. Here, the ONU 10-1 will be described as an example, but the operations of the ONUs 10-2 and 10-3 are the same as the operation of the ONU 10-1.

  First, the operation of the OLT 1 will be described. The OLT 1 stores the downlink data received from the upper network 50 in the downlink buffer 4. The PON control unit 2 reads the downlink data stored in the downlink buffer 4 and transmits it to the ONUs 10-1 to 10-3 via the optical transceiver 5 and the WDM 6. The PON control unit 2 generates a control signal such as a transmission permission signal for communicating the band allocation result, and transmits the control signal to the ONUs 10-1 to 10-3 via the optical transceiver 5 and the WDM 6. The optical transceiver 5 converts the electrical signal input from the PON control unit 2 into an optical signal. The WDM 6 wavelength-multiplexes the optical signal input from the optical transceiver 5 and sends it to the optical fiber 30.

  The optical transceiver 5 converts an optical signal received from the ONUs 10-1 to 10-3 via the WDM 6 into an electrical signal and inputs the electrical signal to the PON control unit 2. The PON control unit 2 stores upstream data to be transmitted from the optical transceiver 5 to the upper network 50 among the electrical signals in the upstream buffer 3. The PON control unit 2 performs a process according to the PON protocol such as a band allocation process based on the received control signal for a control signal such as a band request signal among the electric signals from the optical transceiver 5.

  Next, the operation of the ONU 10-1 will be described. The optical transceiver 14 converts an optical signal received from the OLT 1 via the WDM 15 into an electrical signal and inputs the electrical signal to the PON control unit 11. The PON control unit 11 stores the downlink data received from the OLT 1 via the optical transceiver 14 in the downlink buffer 13. The PON control unit 11 performs an operation based on the control signal received from the OLT 1. Further, the PON control unit 11 reads the downlink data from the downlink buffer 13 and transmits the downlink data to the destination network devices 20-1 and 20-2.

  Further, the PON control unit 11 stores the uplink data received from the network devices 20-1 and 20-2 in the uplink buffer 12. The PON control unit 11 reads the uplink data stored in the uplink buffer 12 and transmits the uplink data to the OLT 1 via the optical transceiver 14 and the WDM 15 based on the band allocation result notified from the OLT 1. The PON control unit 11 generates a control signal such as a band request signal and transmits the control signal to the OLT 1 via the optical transceiver 14 and the WDM 15.

  Next, bandwidth allocation control according to the present embodiment will be described. In the present embodiment, similarly to the conventional PON system, the bandwidth allocation control is performed using the bandwidth request signal (Report message, etc.) and the transmission permission signal (Gate message, Grant message, etc.) for the upstream communication bandwidth. . Hereinafter, the Report message is taken as an example of the band request signal and the Gate message is taken as an example of the transmission permission signal, but the formats of the band request signal and the transmission permission signal are not limited thereto.

  FIG. 2 is a diagram illustrating an example of message exchange regarding bandwidth allocation between the OLT 1 and the ONU 10. As shown in FIG. 2, the OLT 1 periodically transmits a Gate message (steps S1, S3, S6), for example. This Gate message stores the bandwidth (for example, transmission start time and transmission amount) allocated to each ONU by the bandwidth allocation unit 21 of the PON control unit 2 of the OLT 1. The OLT 1 allocates a band for transmitting the Report message to the ONU 10 that has not notified the requested band (the requested band is 0). The OLT 1 allocates a band for transmitting a Report message and a band for transmitting uplink data to the ONU 10 that notifies the requested band (the requested band is not 0). There is no restriction on the bandwidth allocation algorithm executed by the bandwidth allocation unit 21, and any algorithm may be used. For example, ITU-T Recommendation G. There are SR method, NSR method and the like defined in 983.4.

  The bandwidth request unit 113 of the PON control unit 11 of the ONU 10 determines a requested bandwidth based on the amount of data stored in the downlink buffer 13 and the adjustment result of the requested bandwidth described later, and sends a Report message storing the requested bandwidth. It is generated and transmitted to the OLT 1 via the optical transceiver 14 and the WDM 15 (steps S2 and S5). When the PON control unit 11 of the ONU 10 is notified of the bandwidth for the uplink data (for example, the data transmission start time and the data transmission amount) by the Gate message, the upstream data is transmitted to the upstream buffer based on the notified bandwidth. 12 is transmitted to the OLT 1 via the optical transceiver 14 and the WDM 15 (step S4).

  A concentrator network such as an optical access system typified by a PON system includes a buffer memory that temporarily stores data in order to compensate for a communication speed difference between different devices. Specifically, the OLT 1 temporarily stores upstream data transmitted from the ONUs 10-1 to 10-3 in the upstream buffer 3, and transmits data to the upstream network 50 in accordance with the communication speed of the upstream network 50. The ONUs 10-1 to 10-3 temporarily store the upstream data transmitted from the network devices 20-1 and 20-2 in the upstream buffer 12, and store the upstream data to the OLT 1 based on the transmission permission signal from the OLT 1. Send.

  Uplink data stored in the uplink buffer 12 included in the ONUs 10-1 to 10-3 may include uplink data to be subject to priority control. When priority control is performed, uplink data having a high priority is transmitted with priority, but any specific control method may be used without any particular limitation.

  As described above, the ONU 10 transmits uplink data to the OLT 1 based on the transmission permission signal from the OLT 1. The band notified by this transmission permission signal differs depending on the allocation control method in the OLT 1. Therefore, for example, an excessive band may be allocated to data actually transmitted by the ONU 10, and conversely, an excessive band may be allocated. Therefore, the amount of data actually transmitted by the ONU 10 does not always match the band permitted by the transmission permission signal.

  Further, the uplink data received by the ONU 10 from the network devices 20-1, 20-2, etc. changes with time. When the increase rate of the uplink data is remarkable, it is conceivable that the amount of data stored in the uplink buffer 12 will increase rapidly in the future, and it is more efficient to request more bandwidth. Further, when the uplink data has a decreasing tendency, the amount of data stored in the uplink buffer 12 in the future decreases. For this reason, for example, if the upstream buffer 12 does not overflow, there is virtually no problem even if the required bandwidth is reduced, and this reduced portion is used for transmission of upstream data of the other ONUs 10-1 to 10-3. May be efficient overall.

  From the above, in this embodiment, the ONU 10 includes the communication monitoring unit 111 and the communication amount comparison unit 112. Then, the communication monitoring unit 111 monitors the bandwidth (data transmission amount) notified from the OLT 1 and the data amount actually transmitted from the ONU 10 to the OLT 1. Through this monitoring, the communication monitoring unit 111 changes the rate of change (first rate of change) of the bandwidth (data transmission amount) notified from the OLT 1 and the rate of change (first rate of data actually transmitted by the ONU 10 to the OLT 1). 2 change rate). The communication amount comparison unit 112 calculates a difference between the data transmission amount notified by the transmission permission signal and the data amount actually transmitted from the ONU 10 to the OLT 1. The ratio between the difference and the data transmission amount notified by the transmission permission signal is defined as an increase / decrease rate. The bandwidth request unit 113 determines a requested bandwidth based on the amount of upstream data stored in the upstream buffer 12 and one or more of the first change rate, the second change rate, and the increase / decrease rate.

  FIG. 3 is a diagram illustrating an example of a required bandwidth determination processing procedure according to the present embodiment. The communication monitoring unit 111 monitors the allocated bandwidth (data transmission amount) notified based on the transmission permission signal from the OLT 1 (step S1). The communication monitoring unit 111 monitors the amount of data actually transmitted from the ONU 10 to the OLT 1 (step S2). The communication monitoring unit 111 changes the change rate (first change rate) of the bandwidth (allocated bandwidth) notified from the OLT 1 and the change rate (second change rate) of the data amount actually transmitted from the ONU 10 to the OLT 1. Are calculated (step S3). The communication amount comparison unit 112 calculates the difference between the data transmission amount notified by the transmission permission signal and the data amount actually transmitted from the ONU 10 to the OLT 1 (step S4). Further, the communication amount comparison unit 112 calculates an increase / decrease rate based on the difference calculated in step S4 (step S5).

  The bandwidth request unit 113 calculates the requested bandwidth based on the uplink data amount stored in the uplink buffer 12 and one or more of the first change rate, the second change rate, and the increase / decrease rate (step S6). ). The bandwidth request unit 113 stores the calculated request bandwidth in a bandwidth request signal and transmits it to the OLT 1 (step S7).

  The bandwidth request unit 113 determines the requested bandwidth to be notified to the OLT 1 based on the uplink data amount stored in the uplink buffer 12 and one or more of the first change rate, the second change rate, and the increase / decrease rate. Various methods are conceivable and any method may be used. For example, the following method is used. In any method, first, a requested bandwidth based on the amount of uplink data stored in the upstream buffer 12 (requested bandwidth based on the accumulated amount) is calculated, and the first bandwidth is calculated with respect to the requested bandwidth based on this accumulated amount. Based on one or more of the change rate, the second change rate, and the increase / decrease rate, the request bandwidth is obtained by increasing or decreasing the request bandwidth.

(A) Method using the second rate of change Based on the second rate of change, that is, the rate of change of the amount of data actually transmitted by the ONU 10 to the OLT 1, the amount of transmitted data continuously increases. Can be determined, a value obtained by adding a value corresponding to the second rate of change from the requested bandwidth based on the accumulated amount to the requested bandwidth based on the accumulated amount is set as the requested bandwidth to be notified. Further, when it can be determined that the amount of transmitted data is continuously decreasing based on the rate of change of the amount of data actually transmitted by the ONU 10 to the OLT 1, the value corresponding to the second rate of change is stored. The value subtracted from the requested bandwidth based on the above is used as the requested bandwidth to be notified (notified bandwidth).

(B) Method Using Increase / Decrease Rate When the increase / decrease rate is 1, that is, when the data transmission amount notified by the transmission permission signal matches the data amount actually transmitted to the OLT 1 by the ONU 10 A value larger than the requested bandwidth based on the accumulated amount is set as a requested bandwidth to be notified, for example, by adding this value to the requested bandwidth based on the accumulated amount. Further, when the increase / decrease rate is smaller than the threshold value, that is, when the data amount actually transmitted to the OLT 1 by the ONU 10 is smaller than the data transmission amount notified by the transmission permission signal, the value corresponding to the increase / decrease rate is based on the accumulated amount. The value subtracted from the requested bandwidth is used as the requested bandwidth to be notified.

(C) Method of combining second change rate and increase / decrease rate Based on the second change rate, it is not determined that the data transmission amount notified by the transmission permission signal has increased continuously, and the increase / decrease rate is 1 In this case, a value larger than the requested bandwidth based on the accumulated amount is set as a requested bandwidth to be notified by adding a predetermined value to the requested bandwidth based on the accumulated amount. Also, based on the second rate of change, if it is not determined that the data transmission amount notified by the transmission permission signal has continuously decreased and the rate of increase / decrease is smaller than the threshold value, a value corresponding to the rate of increase / decrease is accumulated. The value subtracted from the requested bandwidth based on the amount is set as the requested bandwidth to be notified.

  In the above example, since the first rate of change is not directly used, the first rate of change need not be calculated, but the requested bandwidth is determined in more detail using the first rate of change. You may make it do.

  Although the increase / decrease rate is used here, instead of the increase / decrease rate, it is directly based on the difference between the data transmission amount notified by the transmission permission signal and the data amount actually transmitted to the OLT 1 by the ONU 10. A band to be added to or subtracted from the requested band based on the accumulated amount may be obtained.

  As described above, in the present embodiment, the communication monitoring unit 111 monitors the bandwidth (data transmission amount) notified from the OLT 1 and the data amount actually transmitted from the ONU 10 to the OLT 1, and the ONU 10 performs the OLT 1. The rate of change in the amount of data actually transmitted is calculated. Further, the communication amount comparison unit 112 obtains a difference between the data transmission amount notified by the transmission permission signal and the data amount actually transmitted from the ONU 10 to the OLT 1, and obtains an increase / decrease rate based on the difference. Then, the bandwidth request unit 113 determines the requested bandwidth to be notified to the OLT 1 based on the upstream data amount stored in the upstream buffer 12 and one or more of the above change rate and increase / decrease rate. did. For this reason, efficient bandwidth allocation can be realized and the capacity of the buffer memory (upstream buffer 12) of the ONU 10 can be reduced.

  As described above, the slave station device, the master station device, the control device, the optical communication system, and the bandwidth allocation control method according to the present invention are useful for the PON system.

  1 OLT, 2,11 PON control unit, 3,12 upstream buffer, 4,13 downstream buffer, 5,14 optical transceiver, 6,15 WDM, 10-1 to 10-3 ONU, 20-1, 20-2 Network equipment, 21 Band allocation unit, 30 Optical fiber, 40 Splitter, 111 Communication monitoring unit, 112 Traffic volume comparison unit, 113 Band request unit

Claims (14)

A slave station device that is connected to the master station device by an optical communication path, and is assigned from the master station device with an upstream communication band that is a direction toward the master station device,
A communication monitoring unit for monitoring the amount of transmission data transmitted to the master station device;
A bandwidth request unit that calculates a notification bandwidth that is a request bandwidth requested to the master station device based on the transmission data amount, and notifies the master station device of the notification bandwidth;
A slave station device comprising: The communication monitoring unit obtains a change rate of the transmission data amount,
The slave station apparatus according to claim 1, wherein the bandwidth request unit calculates the notification bandwidth based on the transmission data amount. An upstream buffer for storing data to be transmitted to the master station device;
When the bandwidth request unit determines that the transmission data transmitted to the master station device has continuously increased based on the rate of change, the bandwidth request unit is calculated based on the accumulation amount accumulated in the uplink buffer. The slave station apparatus according to claim 2, wherein a value obtained by adding a value corresponding to the rate of change to a requested band based on a quantity is calculated as the notification band. An upstream buffer for storing data to be transmitted to the master station device;
If the bandwidth request unit determines that the transmission data transmitted to the master station device has continuously decreased based on the change rate, the bandwidth request unit is calculated based on the accumulation amount accumulated in the uplink buffer. The slave station apparatus according to claim 2 or 3, wherein a value obtained by subtracting a value corresponding to the rate of change from a request band based on a quantity is calculated as the notification band. The communication monitoring unit further monitors the allocated bandwidth allocated from the master station device,
The slave station apparatus according to claim 1, wherein the bandwidth request unit determines the requested bandwidth based on a difference between the allocated bandwidth and the transmission data amount. An upstream buffer for storing data to be transmitted to the master station device;
6. The bandwidth request unit according to claim 5, wherein, when determining that the allocated bandwidth and the transmission data amount match, the bandwidth request unit calculates a value larger than the storage amount stored in the uplink buffer as the notification bandwidth. The slave station device described. An upstream buffer for storing data to be transmitted to the master station device;
When the bandwidth request unit determines that the amount of transmission data is smaller than the allocated bandwidth, a value corresponding to the difference is obtained in a requested bandwidth based on an accumulated amount calculated based on an accumulated amount accumulated in the uplink buffer. The slave station apparatus according to claim 5, wherein a value obtained by subtracting is calculated as the notification band. The communication monitoring unit further monitors the allocated bandwidth allocated from the master station device,
The bandwidth request unit obtains a change rate of the transmission data amount, and determines the request bandwidth based on a difference between the allocated bandwidth and the transmission data amount and the change rate. The slave station device described. An upstream buffer for storing data to be transmitted to the master station device;
When the bandwidth request unit determines, based on the change rate, that transmission data transmitted to the master station device does not continuously increase and determines that the allocated bandwidth matches the transmission data amount 9. The slave station apparatus according to claim 8, wherein a value larger than the accumulation amount accumulated in the uplink buffer is calculated as the notification band. An upstream buffer for storing data to be transmitted to the master station device;
The bandwidth request unit, based on the rate of change, determines that transmission data transmitted to the master station device is not continuously reduced, and determines that the transmission data amount is smaller than the allocated bandwidth, 10. The notification band according to claim 8, wherein a value obtained by subtracting a value corresponding to the difference from a request band based on an accumulation amount calculated based on an accumulation amount accumulated in an upstream buffer is calculated as the notification band. The slave station device described.   An uplink communication band, which is connected to the slave station device according to any one of claims 1 to 10 by an optical communication path and is directed from the slave station device to itself, is allocated to the slave station device. A featured master station device. A control device in the slave station device, which is connected to the master station device by an optical communication path, and is assigned from the master station device with an upstream communication band that is a direction toward the master station device,
A communication monitoring unit for monitoring the amount of transmission data transmitted to the master station device;
A bandwidth request unit that calculates a notification bandwidth that is a request bandwidth requested to the master station device based on the transmission data amount, and notifies the master station device of the notification bandwidth;
A control device comprising: The slave station device according to any one of claims 1 to 10,
A master station device that allocates an upstream communication band from the slave station device to the slave station device;
An optical communication system comprising: A bandwidth allocation control method in a slave station device, which is connected to the master station device by an optical communication path and is allocated from the master station device with an upstream communication band that is a direction toward the master station device,
A first step of monitoring a transmission data amount transmitted to the master station device;
A second step of calculating a notification band which is a request band to be requested to the parent station device based on the transmission data amount, and notifying the notification band to the parent station device;
A bandwidth allocation control method comprising:

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