JP4244746B2 - Optical subscriber line terminal equipment and bandwidth allocation method used thereby - Google Patents

Description

  The present invention relates to a PON (Passive Optical Network) that is a medium-shared communication in which a plurality of home-side devices share a medium and transmit data, and in particular, EPON (Transmission of data as an Ethernet (R) frame) The present invention relates to an OLT (optical subscriber line terminal equipment) that efficiently allocates an upstream band in Ethernet (R) PON), an ONU (optical subscriber line terminal equipment) connected thereto, and a bandwidth allocation method used by them.

  In recent years, the Internet has become widespread, and users can access various information on sites operated in various parts of the world and obtain the information. Along with this, the demand for broadband access such as ADSL (Asymmetric Digital Subscriber Line) and FTTH (Fiber To The Home) is also increasing rapidly.

  FIG. 31 is a block diagram showing a schematic configuration of a conventional PON system. This PON system mainly branches an OLT 101 installed in a telephone office or the like, a plurality of ONUs 102-1 to 102-n mainly installed in each home, and an optical signal transmitted from the OLT 101 to split the ONU 102-1. 102-n, a splitter 105 for converging optical signals sent from the ONUs 102-1 to 102-n and sending them to the OLT 101, and a user terminal 111 connected to each of the ONUs 102-1 to 102-n including. Note that the first ONU 102-1 to the n-th ONU 102-n have the same configuration.

  The OLT 101 sends the data received via the upper network 109 to the ONUs 102-1 to 102-n via the transmission path 104 and the splitter 105. Further, the OLT 101, based on the report 107 transmitted from the ONUs 102-1 to 102-n, transmits the transmission start time of data stored in the buffers 103-1 to 103-n in the ONUs 102-1 to 102-n and The grant permission amount is calculated, and the grant 106 into which the instruction signal is inserted is sent to the ONUs 102-1 to 102-n via the transmission path 104 and the splitter 105.

  For example, when the ONU 102-1 receives the uplink information frame 108 from the user terminal 111 via the lower network 110, the uplink information frame 108 is temporarily stored in the buffer 103-1. When the ONU 102-1 receives the grant 106 from the OLT 101, the ONU 102-1 notifies the OLT 101 with the report 107 of the data amount in the buffer 103-1 at the time designated by the grant 106. The uplink information frame 108 arrives in variable length packet units.

  When the ONU 102-1 receives the grant 106 in which the instruction signal is inserted from the OLT 101, the ONU 102-1 transmits the data in the buffer 103-1 to the OLT 101 together with the report 107 based on the instruction signal.

  FIG. 32 is a sequence diagram for explaining the operation procedure of the conventional PON system. This sequence diagram is for the operations of the OLT 101 and the ONU 102-1, but the same is true for the operations of the other ONUs 102-2 to 102-n.

  At the operation time start time T0, the OLT 101 has already calculated an RTT (Round Trip Time) for the ONUs 102-1 to 102-n. At time Ta1, the OLT 101 transmits a grant 121 including the report transmission start time Tb2 to the ONU 102-1, in order to notify the transmission request amount. This report transmission start time Tb2 is calculated so as not to collide with reports transmitted from other ONUs.

  When the ONU 102-1 receives the grant 121 for itself, the ONU 102-1 calculates the requested transmission amount by referring to the data amount stored in the buffer 103-1, and the OLT 101 receives the report transmission start time Tb2 included in the grant 121. A report 122 including the requested transmission amount is transmitted.

  When the OLT 101 receives the report 122, the OLT 101 calculates a value that is equal to or less than the fixed or variable maximum allowable transmission amount and can transmit as much data as possible in the buffer included in the report 122, and grants the calculation result as the allowable transmission amount. 123. When the transmission request amount included in the report 122 is zero, the operation result by the OLT 101 is zero and no bandwidth is allocated. However, since the ONU 102-1 needs to transmit the report, the OLT 101 causes the ONU 102-1 to send the report. The grant 123 is always transmitted.

  The transmission start time Tb4 included in the grant 123 uses the calculated scheduled ONU data reception time, the previous ONU transmission permission amount, the RTT related to the current ONU, and the guard time which is a fixed time, and data and reports. Is calculated so as not to collide with data or reports from other ONUs. The OLT 101 calculates a time Ta3 at which the grant 123 including the transmission permission amount and the transmission start time Tb4 is transmitted so that the grant 123 arrives at the ONU 102-1 by the transmission start time Tb4.

  When the ONU 102-1 receives the grant 123 for itself, the ONU 102-1 sends the data 124 corresponding to the transmission permission amount to the OLT 101 together with the report including the next transmission request amount at the transmission start time Tb4 included in the grant 123. This report is sent immediately before or after the data. When the report is sent immediately before the data, the value to be reported to the OLT 101 as the send request amount is the data amount stored in the buffer 103-1 and the data 124. This is the difference from the amount of data.

  When the OLT 101 receives the data and the report 124, the OLT 101 sends the data to the upper network 109, and the report is processed in the same manner as the processing for the report 122. The processing described above is performed independently for all the ONUs 102-1 to 102-n, and the processing from time Ta3 to time Ta4 is repeated until the operation time ends.

  FIG. 33 is a diagram illustrating an example of a distributed allocation method. This diagram is a sequence diagram showing bandwidth allocation when the number of ONUs is 3, and transmission / reception of grants and reports between OLT-ONUs.

  The OLT 101 sequentially sends grants 131 to 133 to the ONUs 102-3, 102-2, and 102-1. When the OLT 101 receives the reports 134 to 136 from the ONUs 102-3, 102-2, and 102-1, it first sends a grant 137 to the ONU 102-3 that permits transmission of data.

  The OLT 101 receives the data 138 sent from the ONU 102-3 and sends a grant 139 to the ONU 102-2 in parallel with this. Thereafter, similar processing is repeated, and the OLT 101 sequentially allocates bands to the ONUs 102-1 to 102-3 and repeats data reception.

  As can be seen from FIG. 33, the waiting time from when the data sent from the user terminal 111 arrives at the ONU 102-1 until it is sent is the data corresponding to the report after the ONU 102-1 sends the report. Depends on the time to send That is, it varies depending on the amount of data transmitted from all ONUs 102-1 to 102-3.

  For example, if all the transmission request amounts by the reports from the ONUs 102-1 to 102-n shown in FIG. 31 are permitted, the waiting time from the transmission of the report to the transmission of data is greatly increased, which affects the service that requires real-time. As well as greatly affecting TCP (Transmission Control Protocol) throughput. Therefore, the OLT 101 needs to control the amount of data transmitted from the ONUs 102-1 to 102-n so that the waiting time in the buffer in the ONU can be suppressed within an allowable time.

  In order to solve this problem, after the OLT 101 receives a report from the ONUs 102-1 to 102-n, a credit (maximum transmission permission amount) is used to limit the transmission permission amount of the ONUs 102-1 to 102-n. The concept is introduced. If the total number of ONUs that can be transmitted is N, the line speed of the transmission path 104 is r [bps], and the allowable delay time is td [sec], the credit c [bit] is calculated by the following equation.

c = r × td / N (1)
As described above, the OLT 101 allocates a fixed amount of credit to each of the ONUs 102-1 to 102-n, and controls the amount of data transmitted from the ONUs 102-1 to 102-n. The data transmission waiting time in the buffers 103-1 to 103-n is suppressed within an allowable time.

  As a related prior art, “IPACT: A Dynamic Protocol for an Ethernet® PON” (Glen Kramer et al., Pp74-80, IEEE Commun, Feb. 2002.) (hereinafter referred to as the first prior art). ) And “Dynamic Bandwidth Allocation Algorithm Suitable for GE-PON” (Yoshihara et al., IEICE Technical Report, NS2002-17, pp1-4, 2002.04) (hereinafter referred to as second prior art).

  The first prior art relates to a dynamic allocation method in the EPON type FTTH service, in which the OLT sends a report to each ONU independently, and each time the OLT issues a grant to the corresponding ONU. It relates to the allocation method.

The second prior art relates to a centralized allocation method, in which the ONU has a buffer amount up to the maximum data size that can be allocated per grant period, and a buffer amount that is less than or equal to the specified upper limit from the beginning of the buffer. Are sent as a report. The OLT permits a buffer amount equal to or less than the upper limit value in order from the first ONU, and reduces the allocation loss by giving the unallocated bandwidth as a grant only to the last ONU of the grant period.
"IPACT: A Dynamic Protocol for an Ethernet (R) PON" (Glen Kramer et al., Pp74-80, IEEE Commun, Feb. 2002.) “Dynamic Bandwidth Allocation Algorithm Suitable for GE-PON” (Yoshihara et al., IEICE Tech. Technical Report, NS2002-17, pp1-4,2002.04)

  In the method of assigning the credit calculated by the equation (1) to each ONU, there is a problem that if the credit is small, even if only a small number of ONUs can monopolize the line, the uplink bandwidth cannot be used efficiently. there were.

  FIG. 34 is a diagram for explaining a problem in the first prior art. When the OLT recognizes only the transmission permission band for the transmission request amount (buffer declaration amount) included in the report received from the ONU # 1, the ONU # 1 uses the MAC (Media Access) for the transmission permission band. Control) frames 141, 142, and 143 are transmitted, but an allocation loss occurs because the MAC frame 144 cannot be transmitted within the permitted transmission band.

  Similarly, ONU # 2 cannot send MAC frame 153 within the transmission-permitted band, and ONU # 3 cannot send MAC frame 163 within the transmission-permitted band, so an allocation loss occurs. This allocation loss corresponds to the maximum MAC frame length in the worst case. Therefore, there is a problem that the uplink information frame cannot be efficiently transmitted.

  In the second prior art, the number of ONUs to which the OLT gives a large permitted amount within the same period is one, and the other ONUs can only allocate a small permitted amount, so the uplink information frame is stored in the buffer. There was a problem that the time is long. In the second prior art, a fixed maximum transmission permission amount is allocated from the OLT when the ONU is connected.

The present invention has been made to solve the above problems, the purpose of that, the optical line termination capable of determining the credits allocated to each queue in accordance with the baseband section of the queue And a bandwidth allocation method used thereby.

  An optical subscriber line terminal apparatus according to claim 1 is an optical subscriber line terminal apparatus that sends a grant in response to a report from an optical subscriber line termination apparatus. First receiving means for receiving data and reports, first transmitting means for sending data received by the first receiving means to the upper network, and reports received by the first receiving means The maximum transmission permission amount of each queue is calculated according to the request amount of the queue length of each queue included in each queue and the bandwidth classification of each queue, a grant including the calculated maximum transmission permission amount is generated, Generating means for generating a grant so that the sending permission amount of each queue is equal to or less than the maximum sending permission amount of each queue with respect to the sending request amount of each queue included in the report received by the receiving means; Second receiving means for receiving data from the network, storage means for storing the data received by the second receiving means and the grant generated by the generating means, and data stored by the storing means And a second transmission means for sending the grant to the optical subscriber line terminating device.

The generation unit calculates the maximum transmission permission amount of each queue according to the request amount of the queue length of each queue included in the report received by the first reception unit and the bandwidth classification of each queue. Allocation can be performed according to the bandwidth classification, and the maximum transmission permission amount is notified using the grant, so that it is possible to suppress the transmission request amount included in the report received in the next period.
An optical subscriber line terminal apparatus according to claim 2 is an optical subscriber line terminal apparatus that sends a grant in response to a report from the optical subscriber line termination apparatus. First receiving means for receiving data and reports, first transmitting means for sending data received by the first receiving means to the upper network, and reports received by the first receiving means The maximum transmission permission amount of each queue is calculated according to the queue length request amount of each queue included in each queue and the bandwidth classification of each queue, and the calculated maximum transmission permission amount is notified to the optical subscriber line terminating equipment. Generation for generating a grant so that the transmission permission amount of each queue is equal to or less than the maximum transmission permission amount of each queue with respect to the transmission request amount of each queue included in the report received by the first receiving means in the cycle hand A second receiving means for receiving data from the upper network, a storage means for storing the data received by the second receiving means and the grant generated by the generating means, and stored by the storing means Second transmission means for transmitting the received data and grant to the optical subscriber line terminating device.

The optical subscriber line terminal apparatus according to claim 3 is the optical subscriber line terminal apparatus according to claim 1 or 2 , wherein the generating means is included in the report received by the first receiving means. It is determined whether each queue of the optical subscriber line terminating equipment is active by referring to the request amount of the queue length of each queue, and information on whether each queue is active and the bandwidth classification of each queue. In response, the maximum transmission permission amount of each queue is calculated, the calculated maximum transmission permission amount is notified to the optical subscriber line terminating device, and each queue included in the report received by the first receiving means in the next period The grant is generated so that the transmission permission amount of each queue is equal to or less than the maximum transmission permission amount of each queue with respect to the transmission request amount.

  Since the generating means determines whether or not each queue of the optical subscriber line terminating device is active with reference to the request amount of the queue length of each queue, it becomes possible to allocate the band more efficiently.

An optical subscriber line terminal apparatus according to claim 4 is the optical subscriber line terminal apparatus according to any one of claims 1 to 3 , wherein the generation unit is configured to grant a grant period to a fixed queue. The value obtained by subtracting the transmission request amount from the scheduled arrival data amount is set as the maximum transmission permission amount every time, and the scheduled arrival data amount is set again as the maximum transmission permission amount when the data arrival interval elapses.

  Since the value obtained by subtracting the transmission request amount from the scheduled arrival data amount for each grant cycle is set as the maximum transmission permission amount, the fixed data delay time can be kept small.

The optical subscriber line terminal apparatus according to claim 5 is the optical subscriber line terminal apparatus according to any one of claims 1 to 4 , wherein the generation means is configured for the queues of Assured and Non-Assured. Thus, the maximum transmission permission amount is given only once in a plurality of grant periods.

  Therefore, it is possible to increase the maximum threshold value of the transmission request amount, and prevent the transmission request from being disabled even when the number of optical subscriber line terminal stations or the number of queues increases. Is possible.

The optical subscriber line terminal apparatus according to claim 6 is the optical subscriber line terminal apparatus according to any one of claims 1 to 5 , wherein the generation means is connected to each optical subscriber line terminal apparatus. If the total value of the requested amount of transmission suppressed by the maximum allocated value is equal to or greater than the bandwidth that can be allocated to the Best-Effort, the bandwidth that can be allocated to the Best-Effort is rearranged in order of increasing the requested amount of transmission. If the transmission request amount suppressed by the maximum allocation value is smaller than the average value divided by the number of optical subscriber line terminating equipment to which credit has not yet been allocated, the transmission request amount suppressed by the maximum allocation value is maximized. The bandwidth that can be allocated to Best-Effort is subtracted from the bandwidth that can be allocated to Best-Effort, the transmission request amount suppressed by the maximum allocation value, and the bandwidth that can be allocated to Best-Effort is still When the transmission request amount suppressed by the maximum allocated value is larger than the average value divided by the number of optical subscriber line terminating devices to which no digit is allocated, the average value is set as the maximum permitted transmission amount and the best-effort is set. The average value is subtracted from the band that can be allocated.

  Since the transmission request amount or average value suppressed by the maximum allocated value is set as the maximum transmission permission amount, it is possible to prevent a problem that the optical subscriber line terminating apparatus cannot make a transmission request even though the transmission request amount is small. It becomes possible.

The optical subscriber line terminal device according to claim 7 is the optical subscriber line terminal device according to any one of claims 1 to 5 , wherein the generation means is provided from each optical subscriber line terminal device. Bandwidth that can be allocated to Best-Effort sequentially from the optical subscriber line terminator pointed to by the pointer if the total value of the transmission request amounts suppressed by the maximum allocation value is equal to or greater than the band that can be allocated to Best-Effort. The transmission request amount suppressed by the maximum allocation value within a range not exceeding the maximum allocation value is set as the maximum transmission permission amount, and the transmission request amount suppressed by the maximum allocation value is subtracted from the band that can be allocated to Best-Effort.

  In order from the optical subscriber line terminating device pointed to by the pointer, the transmission request amount suppressed by the maximum allocation value within the range not exceeding the band that can be allocated to the best-effort is set as the maximum transmission permission amount, so the transmission request amount is small. Nevertheless, it is possible to prevent the problem that the optical subscriber line terminating device cannot make a transmission request.

An optical subscriber line terminal apparatus according to claim 8 is the optical subscriber line terminal apparatus according to any one of claims 1 to 5 , wherein the generation means is connected to each optical subscriber line terminal apparatus. The total transmission request amount suppressed by the maximum allocation value is equal to or greater than the band that can be allocated to Best-Effort, and the transmission request amount suppressed by the maximum transmission permission amount from each optical subscriber line terminating device. If the total is equal to or greater than the bandwidth that can be allocated to Best-Effort, the maximum allocated value was suppressed within the range that does not exceed the bandwidth that can be allocated to Best-Effort in order from the optical subscriber line terminating device indicated by the pointer. The transmission request amount is set as a transmission permission amount, and the transmission request amount suppressed by the maximum allocation value is subtracted from the band that can be allocated to Best-Effort.

  In order from the optical subscriber line terminating device pointed to by the pointer, the transmission request amount that is controlled by the maximum allocation value within the range that does not exceed the bandwidth that can be allocated to the best-effort is set as the transmission permission amount. Nevertheless, it is possible to prevent the problem that the optical subscriber line terminating device cannot make a transmission request.

The optical subscriber line terminal apparatus according to claim 9 is the optical subscriber line terminal apparatus according to any one of claims 1 to 5 , wherein the generation means is connected to each optical subscriber line terminal apparatus. The total transmission request amount suppressed by the maximum allocation value is equal to or greater than the band that can be allocated to the best-effort, and the transmission request amount suppressed by the maximum transmission permission amount from each optical subscriber line terminating device. If the total is less than or equal to the band that can be allocated to Best-Effort, the transmission request amount suppressed by the maximum allocation value is set as the transmission permission amount for a predetermined optical subscriber line terminating device, and then another optical For the subscriber line terminating device, the transmission request amount suppressed by the maximum transmission permission amount is set as the transmission permission amount.

  For a given optical subscriber line termination device, the transmission request amount suppressed by the maximum allocated value was set as the permitted transmission amount, and then the maximum permitted transmission amount was suppressed for other optical subscriber line termination devices. Since the transmission request amount is set as the transmission permission amount, it is possible to perform bandwidth allocation according to the situation.

An optical subscriber line terminal apparatus according to claim 10 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum permitted transmission amount is a multipoint control protocol register. Notification is made using a frame.

  Since the multipoint control protocol register frame is transmitted during the discovery process of the optical subscriber line terminating device, it is advantageous for setting the initial value of the maximum permitted transmission amount.

An optical subscriber line terminal apparatus according to claim 11 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum permitted transmission amount is operations, administration, and maintenance. Notification is made using a frame.

  The Operations, Administration, and Maintenance frame has a function to notify management information, and is therefore suitable for notifying the maximum transmission permission amount.

An optical subscriber line terminal apparatus according to claim 12 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum transmission permission amount is a simple network management protocol. Over User Datagram Protocol / Internet Protocol Notified using packet.

  Simple Network Management Protocol Over User Datagram Protocol / Internet Protocol Since the packet is a standard for notifying management information, it is suitable for notifying the maximum transmission permission amount.

The optical subscriber line terminal apparatus according to claim 13 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum transmission permission amount is a simple network management protocol. Notification is made using an over Ethernet (registered trademark) packet.

  Simple Network Management Protocol Over Ethernet (R) packet is a standard for notifying management information, and is therefore suitable for notifying the maximum permitted transmission amount.

An optical subscriber line terminal apparatus according to claim 14 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum transmission permission amount is a common management information protocol. Notification is made using a packet.

  Common Management Information Protocol Since the packet is an international standard for notifying management information, it is suitable for notifying the maximum transmission permission amount.

An optical subscriber line terminal apparatus according to claim 15 is the optical subscriber line terminal apparatus according to any one of claims 1 to 9 , wherein the maximum permitted transmission amount is a local area network / metropolitan Notification is made using an area network management frame.

  Since the local area network / metropolitan area network management frame is a standard for notifying management information, it is suitable for notifying the maximum transmission permission amount.

The bandwidth allocation method according to claim 16 is a bandwidth allocation method in which an optical subscriber line terminal device sends a grant to a report from an optical subscriber line termination device, wherein the optical subscriber line terminal device Calculating a maximum transmission permission amount of each queue according to a queue length request amount of each queue included in a report received from the optical subscriber line terminating device and a bandwidth classification of each queue, and an optical subscriber line terminal station A step in which the device notifies the optical subscriber line terminating device of the calculated maximum transmission permission amount; and an optical subscriber line terminal device determines that the transmission permission amount of each queue is equal to each queue with respect to the transmission request amount of each queue. Generating a grant so as to be less than or equal to the maximum permitted transmission amount and transmitting the grant to the optical subscriber line terminating device.

The maximum transmission permission amount of each queue is calculated according to the queue length request amount and each queue bandwidth classification included in the report received from the optical subscriber line terminating equipment. It becomes possible to perform according to.
An optical subscriber line terminal apparatus according to claim 17 is an optical subscriber line terminal apparatus that sends a grant in response to a report from the optical subscriber line termination apparatus. First receiving means for receiving data and reports, first transmitting means for sending data received by the first receiving means to the upper network, and reports received by the first receiving means The maximum transmission permission amount is calculated according to the request amount of the queue length of each queue included in the queue, the calculated maximum transmission permission amount is notified to the optical subscriber line terminating device, and is received by the first receiving means in the next period. Generating means for generating a grant so that the transmission permission amount is less than or equal to the maximum transmission permission amount with respect to the transmission request amount of each queue included in the received report, and a second for receiving data from the upper network A receiving means; a storage means for storing the data received by the second receiving means and the grant generated by the generating means; and sending the data and grant stored by the storing means to the optical subscriber line terminating device Second transmission means.
The bandwidth allocation method according to claim 18 is a bandwidth allocation method in which an optical subscriber line terminal device transmits a grant to a report from an optical subscriber line termination device, wherein the optical subscriber line terminal device is A step of calculating a maximum transmission permission amount according to a request amount of the queue length of each queue included in the report received from the optical subscriber line terminating device, and the optical subscriber line terminal station device calculates the calculated maximum transmission permission A step of notifying the optical subscriber line terminating device of the amount, and the optical subscriber line terminal device generating a grant so that the transmission permission amount is less than or equal to the maximum transmission permission amount with respect to the transmission request amount of each queue. Transmitting to an optical subscriber line termination device.

According to the optical subscriber line terminal apparatus according to claim 1 or 2 , the generating means determines the queue length request amount of each queue included in the report received by the first receiving means and the bandwidth classification of each queue. Accordingly, the maximum transmission permission amount of each queue is calculated, so that it is possible to perform bandwidth allocation for each queue according to the bandwidth classification.

According to the optical subscriber line terminal apparatus according to claim 3 , the generation means determines whether or not each queue of the optical subscriber line termination apparatus is active with reference to a request amount of the queue length of each queue. Therefore, it becomes possible to allocate the bandwidth more efficiently.

According to the optical subscriber line terminal apparatus of claim 4 , since a value obtained by subtracting the transmission request amount from the arrival arrival data amount for each grant period is set as the maximum transmission permission amount, the delay time of the fixed data is reduced. It became possible to keep it small.

According to the optical subscriber line terminal apparatus according to claim 5 , the generation means gives the maximum transmission permission amount only once in a plurality of grant periods to the Assured and Non-Assueed queues. The maximum threshold of the amount can be increased, and even when the number of optical subscriber line terminal stations or the number of queues increases, it is possible to prevent the transmission request from being disabled. It was.

According to the optical subscriber line terminal apparatus of claim 6 , the transmission request amount or the average value suppressed by the maximum allocated value is set as the maximum transmission permission amount. It has become possible to prevent the problem that the subscriber line terminating device cannot make a transmission request.

According to the optical subscriber line terminal apparatus of claim 7 , the maximum allocated value is suppressed within a range not exceeding the bandwidth that can be allocated to the best-effort in order from the optical subscriber line terminating device indicated by the pointer. Since the transmission request amount is set as the maximum transmission permission amount, it is possible to prevent a problem that the optical subscriber line terminating device cannot make a transmission request even though the transmission request amount is small.

According to the optical subscriber line terminal apparatus of claim 8 , the maximum allocated value is suppressed in a range not exceeding the bandwidth that can be allocated to the best-effort in order from the optical subscriber line terminating device indicated by the pointer. Since the transmission request amount is set as the transmission permission amount, it is possible to prevent a problem that the optical subscriber line terminating device cannot make a transmission request even though the transmission request amount is small.

According to the optical subscriber line terminal apparatus of claim 9, after a predetermined requested amount of optical subscriber line termination device is set to a transmission permission amount that is a transmission request amount suppressed by the maximum allocation value, For the subscriber line termination device, since the transmission request amount suppressed by the maximum transmission permission amount is set as the transmission permission amount, it becomes possible to perform bandwidth allocation according to the situation.

According to the optical subscriber line terminal device according to claim 10 , the multipoint control protocol register frame in which the maximum transmission permission amount is notified is transmitted at the time of discovery processing of the optical subscriber line termination device. It became advantageous to set the initial value of the maximum sending permission amount.

According to the optical subscriber line terminal apparatus of claim 11 , since the operations, administration, and maintenance frame for notifying the maximum transmission permission amount has a function of notifying management information, the maximum transmission permission is provided. Suitable for notifying the amount.

According to the optical subscriber line terminal apparatus of claim 12 , the simple network management protocol over user datagram protocol / Internet protocol packet in which the maximum transmission permission amount is notified, and the management information is notified. Therefore, it is suitable for notifying the maximum transmission permission amount.

According to the optical subscriber line terminal apparatus of claim 13 , the simple network management protocol over Ethernet (registered trademark) packet in which the maximum transmission permission amount is notified is a standard for notifying management information. Therefore, it is suitable for notifying the maximum transmission permission amount.

According to the optical subscriber line terminal station apparatus of claim 14 , the common management information protocol packet in which the maximum transmission permission amount is notified is an international standard for notifying management information. Suitable for notifying the allowed amount.

According to the optical subscriber line terminal apparatus of claim 15 , the local area network / metropolitan area network management frame in which the maximum transmission permission amount is notified is a standard for notifying management information. Therefore, it is suitable for notifying the maximum transmission permission amount.

  According to the bandwidth allocation method of claim 16, the maximum transmission permission amount of each queue according to the request amount of the queue length of each queue and the bandwidth classification of each queue included in the report received from the optical subscriber line terminating device. Therefore, it becomes possible to perform bandwidth allocation for each queue according to bandwidth classification.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of the OLT according to the first embodiment of the present invention. The OLT 1 receives an optical signal from the ONU and outputs a frame, a transmission unit 12 that transmits a data frame received from the reception unit 11 to a higher-level network, and a report frame received from the reception unit 11. A control frame processing unit 13 that generates a grant frame based on the received data and performs transmission control of a data frame received from the higher level network, a reception unit 14 that receives a frame from the higher level network, and the reception unit 14 It includes a buffer memory 15 that accumulates frames, and a transmission unit 16 that sends frames accumulated in the buffer memory 15 under the control of the control frame processing unit 13 to the ONU. The buffer memory 15 may be any memory that can store data, such as a register, a flip-flop circuit, or a latch circuit.

  The receiving unit 11 receives the optical signal from the ONU and reads the header portion of the frame to determine whether it is a data frame or a control frame such as a report frame. If the received frame is a data frame, the reception unit 11 transfers the data frame to the transmission unit 12. If the received frame is a control frame, the receiving unit 11 transfers the control frame to the control frame processing unit 13.

  When receiving the data frame from the reception unit 11, the transmission unit 12 transmits the data frame to the upper network.

  The control frame processing unit 13 includes a transmission permission amount storage table, a scheduled arrival time storage table, an RTT storage table, and an active information storage table, which will be described later, and has a bandwidth allocation calculation function and a downlink control frame creation function. When receiving a report frame from the receiving unit 11, the control frame processing unit 13 creates a grant frame by a process described later and transfers it to the buffer memory 15. The control frame processing unit 13 also performs transmission control of frames stored in the buffer memory 15.

  The control frame processing unit 13 generates and sends out a control frame for periodically detecting whether or not there is a newly connected ONU, and a table such as an active information storage table according to the detection result. Rewrite the contents of. In addition, when the connected ONU is disconnected, the control frame processing unit 13 detects that and rewrites the contents of a table such as an active information storage table.

  The receiving unit 14 receives a frame from the upper network and transfers it to the buffer memory 15. The buffer memory 15 accumulates the control frames and data frames transferred from the control frame processing unit 13 and the receiving unit 14 in the queue, and transfers the frames accumulated in the queue to the transmission unit 16 under the control of the control frame processing unit 13. . The transmission unit 16 transmits the control frame and data frame transferred from the buffer memory 15 to the ONU.

  FIG. 2 is a flowchart for explaining the processing procedure of the control frame processing unit 13. First, when receiving a report frame from the ONU received by the reception unit 11 (S11), the control frame processing unit 13 refers to the transmission source information in the header of the report frame and corresponds to the transmission source information from the storage table. The ONU information is read (S12).

  FIG. 3 is a diagram illustrating an example of a storage table provided in the control frame processing unit 13. FIG. 3A shows a transmission permission amount storage table in which ONU transmission permission amounts are stored in correspondence with the ONU number k determined to be active at the current time. This transmission permission amount storage table is updated at the time of report / grant frame processing.

  FIG. 3B shows an estimated arrival time storage table, in which the estimated arrival time of the frame is stored in correspondence with the ONU number k determined to be active at the current time. This estimated arrival time storage table is updated at the time of report / grant frame processing.

  FIG. 3C shows an RTT storage table, in which each RTT is stored corresponding to the numbers 1 to N of ONUs that can be transmitted. This RTT storage table is updated when measuring the distance to the ONU.

  FIG. 3D shows an active information storage table, in which information indicating whether each ONU is active is stored in correspondence with ONU numbers 1 to N that can be transmitted. This active information storage table is updated when a new ONU is detected, when an ONU disconnection is detected, and during a report / grant process.

  When a new ONU is detected, information corresponding to the ONU is added to the RTT storage table and the active information storage table. When the disconnection of the ONU is detected, information corresponding to the ONU is deleted from the RTT storage table and the active information storage table.

  When a new ONU is connected to the network, the ONU sends an uplink control frame in response to the downlink control frame periodically sent by the OLT 1. The OLT 1 recognizes that the ONU is connected by receiving the control frame from the ONU, and detects the round trip time between the OLT 1 and the ONU, that is, the RTT based on the response time.

  The OLT 1 determines that the ONU has been disconnected when a report frame is not returned for a certain period of time with respect to the grant frame transmitted to the ONU or when a control frame indicating a disconnection request is received from the ONU.

  Returning to the description of the flowchart of FIG. Next, the control frame processing unit 13 determines the ONU's current arrival schedule from the ONU's estimated arrival time and transmission permission amount processed immediately before the ONU read from the storage table, and the ONU's RTT. The time and the transmission start time are calculated (S13).

  Further, the control frame processing unit 13 refers to the active information storage table, and calculates a credit according to the following equation according to the number of active ONUs and whether or not the ONUs are active (S14). The total number of ONUs that can be transmitted is N, the line speed of the transmission path is r [bps], the allowable delay time is td [sec], and the ratio of active ONUs is α (0 <α ≦ 1). . Here, it is assumed that the active ONU is the ONU whose transmission request amount is not zero among the reports from the previous N ONUs at the time when the transmission permission amount of the ONU is calculated.

c = r × td / (N × α) (2)
By dynamically changing the credits of active ONUs according to equation (2), it is possible to efficiently allocate an upstream band even when only a small number of ONUs are active.

  However, when the credit is calculated using Expression (2), the delay time may exceed the allowable range when the number of active ONUs increases. In particular, since the delay time may increase at the operation start time, it is desirable to use a calculation method that fixes credits as much as possible.

  As another credit calculation method, a method of changing the credit depending on whether or not the ONU transmission request amount was not zero in the previous report can be considered. If the previous transmission request amount of the ONU is zero at the time when the transmission permission amount of the ONU is calculated, the credit of the ONU is expressed by the following equation. Note that M is a fixed value [bit].

c = M (3)
Further, when the previous transmission request amount of the ONU is not zero at the time when the transmission permission amount of the ONU is calculated, the credit of the ONU is calculated by the following equation.

c = M + (r × td−N × M) / (N × α) (4)
If the current transmission request amount of the ONU is zero, the ONU is set as an inactive ONU, and the contents of the storage table are updated. By using this calculation method, the delay time can be suppressed to an allowable value or less, and when a small number of active ONUs can monopolize the bandwidth, the transmission permission amount can be sufficiently increased for the ONUs. it can.

  Next, the control frame processing unit 13 determines whether or not the transmission request amount of the ONU is equal to or less than the calculated credit (S15). If the transmission request amount is equal to or less than the credit (S15, Yes), the transmission permission amount is set as the transmission request amount (S16). Also, if the transmission request amount is larger than the credit (S15, No), the transmission permission amount is set as the credit value (S17).

  Next, the control frame processing unit 13 determines whether the ONU is active at the current time from the transmission request amount. Then, the contents of the storage table are updated depending on whether or not the ONU is active (S18).

  Finally, the control frame processing unit 13 creates a grant frame composed of a transmission source address (OLT address), a transmission destination address (address of the ONU), a transmission start time, and a transmission permission amount, and stores it in the buffer memory 15. The transmission is instructed to transmit this grant frame during the downlink data frame (S19).

  In the above description, the control frame processing unit 13 determines whether or not each ONU is active depending on whether or not the previous transmission request amount (transmission request amount in the previous cycle) of each ONU is zero. However, the previous request amount of transmission of each ONU may be retained several times in a new order, and it may be determined that the ONU is active if the number of request requests that are not zero in the history is equal to or greater than the specified number. .

  Further, as shown in FIG. 4A, it is determined whether the ONU is active based on whether the previous transmission request amount of the ONU (transmission request amount in the previous cycle) is zero, and the ONU is determined to be active. When it is determined that it is not active, the minimum permitted sending amount M is assigned to the ONU. However, as shown in FIG. 4B, it is determined whether the ONU is active depending on whether the previous transmission request amount of the ONU (transmission request amount in the previous period) is L or more. If the ONU is not active, a minimum guaranteed transmission permission amount M may be allocated to the ONU. Here, in L, for example, a maximum MAC frame length of 1522 (when a VLAN tag is included) is set.

  Alternatively, the previous transmission request amount of each ONU may be held several times in a new order, and if the transmission request amount that is L or more in the history is equal to or more than the specified number, it may be determined that the ONU is active.

  Furthermore, the upper limit of the maximum allocation that is different for each service class with different guaranteed bandwidths is set in the ONU, so that many credits are allocated to classes that require a large guaranteed bandwidth, and fewer credits are allocated to classes that have a small guaranteed bandwidth. The delay time of a class that requires a large guaranteed bandwidth may be shortened.

  As described above, according to the OLT 1 in the present embodiment, since the credit (maximum transmission permission amount) is dynamically changed according to the number of active ONUs, the transmission delay time is within a certain time. It is possible to allocate large credits to ONUs that are requesting data transmission.

(Second Embodiment)
The OLT and ONU according to the second embodiment of the present invention eliminate the allocation loss that occurs in the transmission permitted band described with reference to FIG. 18 and prevent a decrease in bandwidth efficiency. The OLT in the present embodiment writes the credit calculated using the formula (2) or the formulas (3) and (4) in the grant frame, and notifies each ONU of the current credit. The ONU that has received the credit notifies the OLT of the maximum amount of data that can be transmitted in units of frames from the first data frame that is equal to or less than the credit and that can be transmitted in units of frames.

  The schematic configuration of the OLT in the present embodiment differs from the schematic configuration of the OLT 1 in the first embodiment shown in FIG. 1 only in that the function of the control frame processing unit is different. Therefore, detailed description of overlapping configurations and functions will not be repeated. Note that the reference numeral of the control frame processing unit in the present embodiment will be described as 13 '.

  The control frame processing unit 13 ′ in the present embodiment has a credit storage table for storing credits of each ONU in addition to the transmission permission amount storage table, the estimated arrival time storage table, the RTT storage table, and the active information storage table. The control frame processing unit 13 ′ refers to the credit storage table and notifies the ONU of the credit.

  FIG. 5 is a block diagram showing a schematic configuration of the ONU according to the second embodiment of the present invention. The ONU 2 receives an optical signal from the OLT and outputs a frame addressed to itself, a transmission unit 22 that transmits a data frame received from the reception unit 21 to a terminal on the user side, and a reception unit 21. A control frame processing unit 23 that generates a report frame based on the received grant frame and controls transmission of a data frame received from the user terminal, and a receiving unit 24 that receives a frame from the user terminal. A buffer memory 25 for storing the data frame received by the receiving unit 24 and the control frame generated by the control frame processing unit 23, and a frame stored in the buffer memory 25 under the control of the control frame processing unit 23 in the OLT. Each data frame received by the transmitting unit 26 to be transmitted and the receiving unit 24 And a counter 27 for counting the length.

  The receiving unit 21 receives an optical signal from the OLT and reads the header portion of the frame to determine whether or not the frame is addressed to itself. The receiving unit 21 takes in the frame if the received frame is addressed to itself, and discards the frame if it is addressed to another ONU or a device connected to another ONU. In addition, the receiving unit 21 determines whether it is a data frame or a control frame such as a grant frame based on the header portion of the captured frame. If the received frame is a data frame, the reception unit 21 transfers the data frame to the transmission unit 22. If the received frame is a control frame, the receiving unit 21 transfers the control frame to the control frame processing unit 23.

  When receiving the data frame from the receiving unit 21, the transmitting unit 22 transmits the data frame to a link to which a user terminal or the like is connected.

  The control frame processing unit 23 includes a data length storage table for storing the length of the data frame transferred from the counter 27, and has a transmission request amount calculation function and an uplink control frame creation function. When the control frame processing unit 23 receives the grant frame from the receiving unit 11, the control frame processing unit 23 creates a report frame by a process described later and transfers it to the buffer memory 25. The control frame processing unit 23 also performs transmission control of frames stored in the buffer memory 25.

  In addition, the control frame processing unit 23 executes processing of control frames other than the grant frame from the OLT, stores the control frames in the buffer memory 25, and performs control frame transmission control.

  The receiving unit 24 receives a frame from a user terminal (link) and transfers the frame to the buffer memory 25. The buffer memory 25 temporarily accumulates the control frames and data frames transferred from the control frame processing unit 23 and the receiving unit 24 for each frame type, and transmits the frames accumulated in the queues under the control of the control frame processing unit 13. Transfer to the unit 26. The transmission unit 26 transmits the control frame and data frame transferred from the buffer memory 25 to the OLT.

  The counter 27 counts the length of the data frame received by the receiving unit 24 and notifies the control frame processing unit 23 of the length of each data frame.

  FIG. 6 is a flowchart for explaining the processing procedure of the control frame processing unit 23. First, when receiving a grant frame from the OLT received by the receiving unit 21 (S21), the control frame processing unit 23 updates the contents of the data length storage table corresponding to the transmission permission amount and includes the grant frame in the grant frame. Credit to be read (S22).

  FIG. 7 is a diagram illustrating an example of the data length storage table. A data length storage table corresponding to each of the queues 1 to Q of the buffer memory 25 is provided. When the data frame is transferred from the receiving unit 24 to the queue in the buffer memory 25, the length of the data frame is detected by the counter 27, and the data length of the data length storage table corresponding to the queue in which the data frame is stored The data length of the data frame is written in order from the top in an area where no is recorded.

  When the grant frame is received, the control frame processing unit 23 deletes the data length corresponding to the transmission permission amount data from the data length storage table, and instructs the buffer memory 25 to transmit the corresponding data frame.

  Further, when creating the report frame, the control frame processing unit 23 reads the data length of the data frame in the priority order for the specified queue. That is, the total amount of data corresponding to the maximum amount of data that can be transmitted in units of frames from the first data frame that is less than or equal to the credit included in the grant frame and that is to be transmitted becomes the transmission request amount.

  Returning to the description of the flowchart of FIG. Next, the control frame processing unit 23 refers to the credit included in the grant frame received from the OLT, and calculates the maximum amount of data that can be transmitted in frame units from the first data frame that is equal to or less than the credit and is transmitted. Then, the value is set as the requested transmission amount (S23).

  Next, the control frame processing unit 23 creates a report frame including a transmission source address (address of the ONU), a transmission destination address (OLT address), and a transmission request amount, and transfers it to the buffer memory 25 (S24). ).

  Finally, the control frame processing unit 23 instructs the buffer memory 25 and the transmission unit 26 to transmit the report frame and the data frame for the transmission permission amount at the transmission start time included in the grant frame (S25).

  FIG. 8 is a flowchart for explaining an OLT processing procedure according to the second embodiment of the present invention. First, when receiving a report frame from the ONU received by the receiving unit 11 (S31), the control frame processing unit 13 ′ determines whether or not the transmission request amount included in the report frame is equal to or less than the credit (S32). ).

  When the transmission request amount is equal to or less than the credit (S32, Yes), the transmission permission amount is set as the transmission request amount (S33). Further, if the transmission request amount is larger than the credit (S32, No), the transmission permission amount is set as the credit value (S34).

  Next, the control frame processing unit 13 ′ determines whether the ONU is active based on the transmission request amount, updates the contents of the storage table (S35), and reads the ONU read from the storage table. From the estimated arrival time and transmission permission amount of the ONU processed one time before and the RTT of the ONU, the current arrival time and transmission start time of the ONU are calculated (S36).

  Also, the control frame processing unit 13 ′ refers to the active information storage table, and determines whether the number of active ONUs and whether the ONU is active or not (2) or (3) and (4). ) To calculate the credit (S37) and update the contents of the credit storage table (S38).

  Finally, the control frame processing unit 13 ′ creates a grant frame composed of a transmission source address (OLT address), a transmission destination address (address of the ONU), a transmission start time, and a transmission permission amount, and creates a buffer memory 15 And instruct the transmission of this grant frame during the downlink data frame (S39).

  FIG. 9 is a sequence diagram for explaining how the transmission timing of the uplink data frame is determined when the OLT 1 transmits the i-th grant frame to the ONU 2, focusing on one ONU 2. is there.

  The i-th grant frame includes a transmission permission amount for the i-th uplink data frame, a transmission start time, and credits allowed for the i + 1-th report. When the ONU 2 receives this grant frame, it transmits to the OLT 1 an i-th report frame including the i + 1-th transmission request amount below credit and an i-th data frame including data equal to or less than the transmission permission amount.

  When the OLT 1 receives the i-th report frame, it determines whether or not the transmission request amount is less than or equal to the credit. If the transmission request amount exceeds the credit, the credit is set as a transmission permission amount. The OLT determines whether the ONU is active by referring to the transmission request amount.

  Next, the OLT 1 calculates the i + 1-th data arrival time of the ONU 2 from the estimated arrival time and the transmission permission amount of the ONU processed immediately before. The OLT 1 can calculate from the data arrival time and the RTT how long the i + 1-th grant frame should be sent to the ONU. Therefore, the OLT 1 can determine the time at which the i + 1th grant frame is transmitted, and can also calculate the transmission start time at which the ONU 2 that has received the grant frame transmits the report frame.

  These calculations can be performed immediately after receiving the report. Credits that have not yet been calculated may be calculated immediately after receiving the report, or may be immediately before the grant frame transmission time in order to use as new information as possible. The OLT 1 sends a grant frame including a sending start time, a sending permission amount and a credit to the ONU 2 at the grant sending time. By repeating the procedure described above and repeating the same processing for other ONUs 2, it is possible to eliminate credit allocation loss.

  As described above, according to the OLT 1 and the ONU 2 in the present embodiment, the ONU 2 calculates the transmission request amount according to the credit included in the grant frame received from the OLT 1, and sends it to the OLT 1. The OLT 1 can eliminate the allocation loss that occurs when the transmission permission amount is allocated to the ONU 2.

  In the above description, the OLT 1 uses the credit amount as the permitted amount of transmission if the transmission request amount from the ONU 2 is larger than the credit. However, the OLT 1 uses the difference between the credit and the transmission request amount from the ONU 2 as follows. The next credit may be increased or decreased.

(Third embodiment)
The OLT according to the first embodiment and the second embodiment of the present invention relates to the OLT using the distributed band allocation method, but the OLT according to the third embodiment of the present invention is concentrated. The present invention relates to an OLT using a type bandwidth allocation method. In the distributed bandwidth allocation method described above, when the OLT receives a report frame from the ONU, the OLT calculates a credit from the traffic situation known at that time, issues a grant frame, and notifies the ONU of the credit and the permitted transmission amount. It was a thing.

  On the other hand, the OLT using the centralized bandwidth allocation method according to the present embodiment waits until report frames from all ONUs arrive, and calculates the credits for each ONU when all the report frames are received. A grant frame is transmitted to each ONU.

  The schematic configuration of the OLT in the present embodiment differs from the schematic configuration of the OLT 1 in the first embodiment shown in FIG. 1 only in that the function of the control frame processing unit is different. Therefore, detailed description of overlapping configurations and functions will not be repeated. Note that the reference numeral of the control frame processing unit in the present embodiment is described as 13a. Since the ONU in the present embodiment is the same as the ONU described in the second embodiment of the present invention, detailed description will not be repeated.

  FIG. 10 is a diagram illustrating an example of a centralized bandwidth allocation scheme according to the third embodiment of the present invention. This diagram is a sequence diagram showing bandwidth allocation when the number of ONUs is 3, and transmission / reception of grants and reports between OLT-ONUs.

  The OLT 1 sequentially sends grants 31 to 33 to the ONUs 2-3, 2-2, and 2-1. When the OLT 1 receives the reports 34 to 36 from the ONUs 2-3, 2-2 and 2-1, the OLT 1 sequentially sends grants 37 to 39 for the ONU 2-3, the ONU 2-2 and the ONU 2-1.

  When the OLT 1 receives the data 43 transmitted from the ONU 2-3, the OLT 1 subsequently receives the data 44 transmitted from the ONU 2-2, and further receives the data 45 transmitted from the ONU 2-1. The OLT 1 generates the next grant for the ONUs 2-1 to 2-3 in parallel with the reception of the data 44 and 45 and sequentially transmits them. Thereafter, the same processing is repeated.

  In FIG. 10, for the sake of simplicity, the grant period start time is defined as the grant transmission start time from the OLT 1, and the grant period start time is indicated by a broken line. The OLT 1 calculates a credit for each ONU based on the report message received in the previous period, and notifies it with a grant frame.

  The difference between the distributed bandwidth allocation method and the centralized bandwidth allocation method is that in the distributed bandwidth allocation method, the information that the ONU is active is determined from the previous transmission request amount of the ONU, and in some cases, the slightly old information is In some cases, the centralized bandwidth allocation method can acquire the amount of transmission requests from all ONUs at almost the same time, so it can be determined whether or not the ONU is active, and credits can be obtained using newer information. It is a point that can be calculated.

  In FIG. 10, OLT 1 transmits only the grant frame to the ONU, and transmits only the report frame to the ONU, and then transmits only the data frame. These data frames may also be transmitted.

  FIG. 11 is a flowchart for explaining an OLT processing procedure according to the third embodiment of the present invention. First, the control frame processing unit 13a substitutes 1 for a variable i (S41), and receives a report frame from the ONU received by the receiving unit 11 (S42). Then, the control frame processing unit 13a determines whether or not the transmission request amount included in the report frame is equal to or less than the credit (S43).

  When the transmission request amount is equal to or less than the credit (S43, Yes), the transmission permission amount is set as the transmission request amount (S44). Further, if the transmission request amount is larger than the credit (S43, No), the transmission permission amount is set as the credit value (S45).

  Next, the control frame processing unit 13a determines whether the ONU is active based on the transmission request amount, updates the contents of the storage table, and increments the variable i by 1 (S46). In the present embodiment, it is assumed that there are as many ONUs as there are transmission permission amount storage tables shown in FIG. 3A and scheduled arrival time storage tables shown in FIG.

  Next, the control frame processing unit 13a determines whether or not the variable i is equal to the number N of ONUs (S47). If the variable i is not equal to the number n of ONUs (S47, No), it is determined that there is an ONU that has not received a report frame, and the process returns to step S42 and the subsequent processing is repeated.

  If the variable i is equal to the number n of ONUs (S47, Yes), the control frame processing unit 13a determines the arrival time and transmission permission amount of the ONU processed immediately before the ONU corresponding to the variable i, The RTU of the ONU is read from the storage table (S48), and the current arrival time and transmission start time of the ONU are calculated (S49).

  In addition, the control frame processing unit 13a refers to the active information storage table, and the expression (2) or the expressions (3) and (4) depending on the number of active ONUs and whether the ONU is active. (S50), the contents of the credit storage table are updated (S51), and the variable i is decremented by 1 (S51).

  Then, the control frame processing unit 13a determines whether or not the variable i is 1 (S52). If the variable i is not 1 (S52, No), it is determined that there is an ONU for which the estimated arrival time and the transmission start time are not calculated, and the process returns to step S48 and the subsequent processing is repeated.

  If the variable i is 1 (S52, Yes), the control frame processing unit 13a is configured by a transmission source address (OLT address), a transmission destination address (address of the ONU), a transmission start time, and a transmission permission amount. A grant frame is created for each ONU and transferred to the buffer memory 15 to instruct the transmission of the grant frame during the downlink data frame (S53).

  As described above, according to the OLT 1 in the present embodiment, even if the centralized bandwidth allocation method is used, the effects described in the first embodiment or the second embodiment can be obtained. Became possible.

(Fourth embodiment)
The OLT 1 in the first embodiment and the second embodiment of the present invention notifies one ONU of one credit even if the ONU has a plurality of queues, and each ONU It was left to assign credits to the queue.

  On the other hand, in the IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 802.3ah standardization committee, a proposal has been made to store a plurality of request amounts for each ONU queue in a report frame. The present embodiment relates to a bandwidth allocation method corresponding to this proposal.

  FIG. 12 is a diagram illustrating an example of the contents of a grant frame issued by the OLT according to the fourth embodiment of the present invention. This grant frame includes a maximum of four permitted transmission amounts, a transmission start time corresponding to each permitted transmission amount, and a maximum permitted transmission amount (credit) corresponding to each queue of the ONU. In addition, the actual grant frame stores a destination address, a transmission source address, and the like in addition to this, but since it is not directly related to the present embodiment, a detailed description thereof will be omitted.

  The OLT 1 can give the transmission permission up to four times to the ONU. When giving a transmission permission for a plurality of times to the ONU, as shown in FIG. 12, the OLT 1 stores a transmission permission amount corresponding to the transmission permission for a plurality of times in the grant frame. The OLT 1 stores a transmission start time corresponding to a plurality of transmission permits in the grant frame.

  The OLT 1 stores credits in the grant frame corresponding to the number of ONU queues. For example, if an ONU that issues a grant frame has eight queues, eight credits are stored in the grant frame, and the corresponding queue number is designated.

  FIG. 13 is a diagram illustrating an example of the contents of a report frame issued by the ONU according to the fourth embodiment of the present invention. This report frame includes a request amount of a queue length for each of up to eight queues and a request amount equal to or less than a credit for each of up to eight queues. In addition, in the actual report frame, a destination address, a transmission source address, and the like are stored in addition to this, but since they are not directly related to the present embodiment, detailed description thereof is omitted.

  FIG. 14 is a flowchart for explaining an OLT processing procedure according to the fourth embodiment of the present invention. First, when receiving a report frame from the ONU received by the receiving unit 11 (S61), the control frame processing unit 13b determines whether or not the transmission request amount of each queue included in the report frame is equal to or less than the credit of each queue. Is determined (S62).

  If the queue send request amount is equal to or less than the queue credit (S62, Yes), the send permission amount is set as the queue send request amount (S63). Also, if the queue send request amount is larger than the queue credit (No in S62), the send permission amount is set to the credit value (S64).

  Next, the control frame processing unit 13b calculates the sum of the transmission permission amounts of the respective queues and sets it as the ONU transmission permission amount (S65). As described above, when the transmission permission is given to the ONU only a plurality of times, the transmission permission amount is also divided into a plurality of calculations. For example, the number of ONU queues is eight, data stored in the first to fourth queues is sent at the first transmission opportunity, and data stored in the fifth to eighth queues is sent for the second time. When sending on occasion, the sum of sending permission amounts corresponding to the first to fourth queues is calculated as the first sending permission amount, and sending corresponding to the fifth to eighth queues as the second sending permission amount. Calculate the total allowed amount.

  Next, the control frame processing unit 13b determines whether each queue of the ONU is active using the queue length for each queue included in the report frame, and updates the contents of the storage table (S66). The current arrival time and transmission start time of the ONU are calculated from the estimated arrival time and transmission permission amount of the ONU processed from the storage table immediately before the ONU and the RTT of the ONU ( S67). Note that an area for storing the queue length of each queue is added to the storage table, and the control frame processing unit 13b rewrites the contents of the area to update the queue length of each queue of the ONU.

  Next, the control frame processing unit 13b refers to the storage table, calculates the credit of each queue of the ONU (S68), and updates the contents of the credit storage table (S69). Below, the credit calculation method for each queue will be described.

  In the present embodiment, ITU (International Telecommunication Union) -TG. According to 983.4, the bandwidth is divided into Fixed, Assured, Non-Assured and Best-Effort, and each queue is characterized by one or a combination of these bandwidth divisions. . The four band sections are assumed to have a high priority in the above order.

  The Fixed and Assured bands are determined at the time of contract between the user of the terminal device connected to the ONU and the connection supplier of the EPON system, and the values are used. Fixed is used when it is necessary to shorten the delay time of transmitted data, such as an IP (Internet Protocol) telephone. This fixed band is determined assuming a fixed frame length. Asserted assumes that the minimum bandwidth determined by the contract is guaranteed.

  Further, the requested bandwidth of Non-Assured and Best-Effort varies dynamically. Non-Assured is allocated in proportion to the bandwidth of the Assured, but the minimum bandwidth is not guaranteed. In Best-Effort, the remaining bandwidth to which Fixed, Assured, and Non-Assured bandwidths are allocated is allocated.

(1) Fixed
A credit BFi for the fixed queue i is calculated and allocated from the bandwidth WFi that is negotiated at the time of the contract. Voice data or the like is assigned to this band division, but the voice data arrives at the ONU at a frequency of about one frame every 20 ms, and it is not efficient to assign credits every grant period. Therefore, when there is a request for transmission of Fixed data, the next transmission request can be predicted by a contract agreement. Therefore, the bandwidth WFi that is negotiated only before and after the predicted cycle is allocated. However, if the request amount of the queue length from the queue that stores only the fixed data is not 0 in a cycle in which no credit is allocated, Fixed is a band segment having a high priority, so credits are allocated. It may be.

(2) Assured
The credit BAi for the queue i of the Assured is calculated and allocated from the bandwidth WAi that is negotiated at the time of the contract. However, since the Assured data is transmitted by a variable-length frame, the ONU rarely uses up all the credits and returns the requested amount of transmission. Therefore, the credit BAi may be allocated in a large amount at a fixed ratio. In order to achieve the contracted bandwidth in the long run, the unused portion of the credit is added to the credit of the next cycle.

(3) Non-Assured
First, the total amount BNA of the bandwidth allocated to the non-assured queue among the queues in all ONUs is determined. This total amount BNA may be determined by the number of all queues, or may be a predetermined constant value. In addition, a maximum allocation amount (hereinafter referred to as maxBNAi) is determined for each queue. Only a maximum bandwidth of maxBNAi is allocated to queue i.

  Further, the total amount BNA for the queue having Non-Assessed is allocated in proportion to the contracted bandwidth WAi of the Assured. Furthermore, assuming that the request amount related to Non-Assured among the queue lengths of each queue is RNAi, the credit BNAi allocated to the active queue in the Non-Assured queue is expressed by the following equation. Note that ΣWAj represents the total sum of the subscribed contracted bands WAi of active queues.

BNAi = min (max BNAi, RNAi, BNA × WAi / ΣWAj) (5)
On the other hand, BNAi is set to 0 for inactive queues. Since the credit is 0, the transmission request amount suppressed below the credit is 0, but the queue length RNAi related to Non-assured is also included in the report frame, so whether or not the queue is active using that value. Determine. A value equal to or smaller than the weighted average distribution BNA × WAi / ΣWAj is used as a threshold for the determination. Note that ΣWAj represents the sum of contracted bandwidths for all queues including Assured connected to the OLT.

  Further, in Expression (5), the request amount RNAi regarding the Non-Assured queue is included, but since there is a time lag between the request time of the queue length by the report frame and the time of notifying the credit, Expression (5) RNAi may be excluded from

  Further, the sum of the credit BNAi calculated by the equation (5), the sum of the transmission request amounts from the ONUs suppressed to the credit BNAi or less, does not exceed the sum of the bandwidths BNA allocated to the non-assured queue. The sum BNA may be set larger. Further, BNAi equal to or less than the weighted average distribution may be given to the inactive queue.

(4) Best-Effort
First, the total amount BB of bandwidth allocated to the best-effort queue among the queues in all ONUs is determined. This total amount BB may be the total allocation amount that can be allocated within one grant period minus the sum of the credit values used for the Fixed, Assured and Non-Assured queues, or for all queues. It may be determined by a number, or may be a predetermined constant value. In addition, a maximum allocation amount (hereinafter referred to as maxBBi) is determined for each queue. Only a maximum bandwidth of maxBBi is allocated to the queue i.

  Also, let RBi be the request amount based on the queue length of the queue related to Best-Effort. Furthermore, if the total amount BB is assigned to each queue in proportion to the request amount according to the queue length of the queue relating to Best-Effort, the credit BBi assigned to the queue i is expressed by the following equation. Note that ΣRBj represents the sum of the request amounts for all the queues including the ONU Best-Effort connected to the OLT. Therefore, for Best-Effect, it is not determined whether the queue is active.

BBi = min (max BBi, RBi, BB × RBi / ΣRBj)
... (6)
In addition, BB × RBi / ΣRBj in Expression (6) may be BB × min (maxBBi, RBi) / Σmin (maxBBj, RBj) constrained by maxBBi. Further, RBi may be excluded when calculating the credit, as in the case of the credit for the non-assured queue.

  In this way, the OLT 1 allocates a credit to each queue of the ONU, but if the sum of the requested amounts from the ONUs that are kept below the credit does not reach the total allocated amount that can be allocated, which ONU Also, a period in which no credit is allocated may be provided, or transmission permission for all queue lengths or more may be given to any ONU queue within a range not exceeding the maximum allocated amount. Good.

  Returning to the description of the flowchart shown in FIG. Finally, the control frame processing unit 13b creates a grant frame configured by a transmission source address (OLT address), a transmission destination address (address of the ONU), a transmission start time, a transmission permission amount, and credits, and creates a buffer memory. 15 to instruct the transmission of the grant frame during the downlink data frame (S70).

  FIG. 15 is a flowchart for explaining the processing procedure of the control frame processing unit 23b in the ONU according to the fourth embodiment of the present invention. First, when receiving a grant frame from the OLT received by the receiving unit 21 (S71), the control frame processing unit 23b updates the contents of the data length storage table corresponding to the transmission permission amount of each queue, and grants the grant frame. The credit of each queue included in the frame is read (S72).

  When receiving the grant frame, the control frame processing unit 23b deletes the data length corresponding to the transmission permission amount data of each queue from the data length storage table, and instructs the buffer memory 25 to transmit the corresponding data frame. To do.

  Next, the control frame processing unit 23b calculates the queue length of each queue with reference to the data length storage table (S73).

  Next, the control frame processing unit 23b refers to the credit of each queue included in the grant frame received from the OLT, and is the maximum amount of data that can be transmitted in units of frames from the first data frame that is equal to or less than the credit and is transmitted. Is calculated for each queue, and the value is set as a request amount for transmission (S74).

  Next, the control frame processing unit 23b reports a report frame configured by a transmission source address (address of the ONU), a transmission destination address (address of OLT), a queue length request amount of each queue, and a transmission request amount of each queue. Is transferred to the buffer memory 25 (S75).

  Finally, the control frame processing unit 23b instructs the buffer memory 25 and the transmission unit 26 to transmit the report frame and the data frame for the transmission permission amount at the transmission start time included in the grant frame (S76).

  Note that only one type of bandwidth classification is not allocated to each queue of the ONU. For example, among the eight queues, it is predetermined that queue 3 stores the data of Assured and Non-Assured, and queue 4 stores only the data of Assured. The correspondence between the bandwidth classification and the queue is defined in IEEE 802.1D according to the number of queues.

  When there are a plurality of bandwidth divisions in one queue, the credit for that queue is the sum of the credits for all bandwidth divisions. For example, when a certain queue stores data of Assured and Non-Assured, it is assumed that a request amount corresponding to Non-Assured is obtained by subtracting the bandwidth BAi of Assured from the request amount related to the queue. Or not, and a credit is calculated. The credit for the queue is obtained by adding the credit related to Assured and the credit related to Non-Assured.

  As described above, according to the OLT and ONU in this embodiment, the OLT calculates credits according to the bandwidth classification of each queue of the ONU and notifies each ONU, and the ONU corresponds to the bandwidth classification of each queue. Since the request amount for each queue is calculated with reference to the credit to be used, the credit that the OLT allocates to each queue of the ONU can be determined according to the bandwidth classification, and the bandwidth allocation to each queue of the ONU is facilitated. It became possible to control.

  In addition, since the OLT determines whether or not the queue is active according to the request amount of the queue length of each queue included in the report frame from the ONU, the OLT credits the queue of the inactive ONU. Can be set to 0, and it becomes possible to allocate the bandwidth more efficiently than in the first and second embodiments.

(Fifth embodiment)
In the fourth embodiment of the present invention, the OLT calculates the credit using the maximum threshold value corresponding to the bandwidth division of each queue of the ONU. However, when the number of ONUs or the number of queues increases, the maximum threshold value for the amount of transmission request for one queue decreases, and it is assumed that the ONU cannot make a transmission request.

  On the other hand, when the number of ONUs or the number of queues increases, if the grant cycle time, which is the basic period of bandwidth allocation, is increased, the arrival time of data that requires a short delay time, such as voice data, will be delayed. . The OLT according to the present embodiment increases the maximum threshold value of the request amount for one queue to some extent while keeping the delay time of data requiring a short delay time short.

  The schematic configuration of the OLT in the present embodiment differs from the schematic configuration of the OLT 1 in the first embodiment shown in FIG. 1 only in that the function of the control frame processing unit is different. Therefore, detailed description of overlapping configurations and functions will not be repeated. Note that the reference numeral of the control frame processing unit of the OLT in the present embodiment is described as 13c.

  FIG. 16 is a flowchart for explaining an OLT processing procedure according to the fifth embodiment of the present invention. First, when receiving a report frame from the ONU received by the receiving unit 11 (S81), the control frame processing unit 13c determines whether or not the transmission request amount of each queue included in the report frame is equal to or less than the credit of each queue. Determine. If the queue send request amount is equal to or less than the queue credit, the send permission amount is set as the queue send request amount. If the queue request amount is larger than the queue credit, the send permission amount is set to the credit value (S82).

  Next, the control frame processing unit 13c calculates the sum of the transmission permission amounts of the respective queues, and sets it as the ONU transmission permission amount (S83). Then, the control frame processing unit 13c determines whether each queue of the ONU is active using the queue length for each queue included in the report frame, and updates the contents of the storage table (S84).

  Next, the control frame processing unit 13c determines whether or not report frames have been received from all ONUs (S85). If there is an ONU that has not yet received a report frame (S85, No), the process returns to step S81 to receive a report frame from the ONU.

  When the report frame is received from all ONUs (S85, Yes), the control frame processing unit 13c determines the ONU scheduled arrival time and the transmission permission amount processed immediately before each ONU from the storage table, and the ONU. RTT is read (S86), and the current arrival time and transmission start time of the ONU are calculated from these pieces of information (S87).

  Next, the control frame processing unit 13c refers to the storage table, calculates the credit of each queue of the ONU (S88), and updates the content of the credit storage table (S89). A method of calculating the credits for each queue will be described later.

  Next, the control frame processing unit 13c determines whether or not calculations have been performed for all ONUs (S90). If there is an ONU that has not been operated (S90, No), the process returns to step S86 and the subsequent processing is repeated.

  If the calculation is performed for all the ONUs (S90, Yes), the control frame processing unit 13c transmits the transmission source address (OLT address), the transmission destination address (address of the ONU), transmission start time, transmission A grant frame composed of the permitted amount and the credit is created and transferred to the buffer memory 15, and an instruction to transmit this grant frame is given during the downlink data frame (S91).

  Here, the credit calculation method for each queue in step S88 will be described.

(1) Fixed
In the fourth embodiment, for each grant cycle time, the estimated arrival data amount for the fixed queue i is calculated from the bandwidth WFi determined at the time of the contract, and assigned as credit BFi. In the present embodiment, the credit is calculated using the data arrival interval F_CYC and the scheduled arrival data amount BFi within the period. The data arrival interval F_CYC is longer than the grant cycle time.

  First, the control frame processing unit 13c notifies BON as a credit to the ONU, and when there is an actual transmission request from the ONU, the control frame processing unit 13c notifies the transmission request amount in the grant frame as a transmission permission amount. In the next grant period, a value obtained by sequentially subtracting the transmission request amount from BFi is notified to the ONU as a credit. When the data arrival interval F_CYC has elapsed, BFI is again notified to the ONU as a credit, and the same processing is repeated. In this way, sending data beyond the contract is prohibited.

(2) Assured, Non-Assured
In the fourth embodiment, the credit is calculated and notified to the ONU every grant cycle time. In the present embodiment, credit is given to the ONU once in a plurality of grant periods, for example, two of the grant periods. For example, the ONU that provides the service is divided into two groups (A and B), and credit is given to the group A with an odd period of the grant, and credit is given to the group B with an even period of the grant. To do. For the ONU to which no credit is allocated, credit 0 is notified in that cycle.

(3) Best-Effort
In the fourth embodiment, the credit is calculated using the transmission request amount suppressed below the credit and the sum of the request amounts for all the queues, and is notified to the ONU. In the present embodiment, the transmission request amount suppressed by credit (hereinafter referred to as request amount A) and the transmission request suppressed by the maximum allocation value (fixed value) that can be allocated in one grant cycle. The credit is calculated using the amount (hereinafter referred to as the required amount B).

  The total amount of bandwidth allocated to the Best-Effect queue is subtracted from the total allocated amount that can be allocated within one grant period, and the total credit value used for the Fixed, Assured, and Non-Assured queues. Shall be.

  The control frame processing unit 13c adds the request amount B when the report frame is received from the ONU, and if the total value of the request amounts B from all ONUs is less than the bandwidth that can be allocated to the Best-Effort. The requested amount B for each ONU is a credit corresponding to the requested amount A.

  If the total value of the request amount B from all ONUs is equal to or greater than the bandwidth that can be allocated to Best-Effort, the control frame processing unit 13c rearranges the request amount B in ascending order, and sequentially performs the following processing To do.

  (I) When the requested amount B is smaller than the average value obtained by dividing the bandwidth that can be allocated to Best-Effort by the number of ONUs to which credit has not yet been allocated, the requested amount B is regarded as a credit corresponding to the requested amount A. , The request amount B is subtracted from the bandwidth that can be allocated to Best-Effort.

  (Ii) If the requested amount B is larger than the average value obtained by dividing the bandwidth that can be allocated to Best-Effort by the number of ONUs to which credit has not yet been allocated, the average value is regarded as a credit corresponding to the requested amount A, The average value is subtracted from the bandwidth allocated to Best-Effort.

  As described above, according to the OLT in the present embodiment, in the case of Fixed, the value obtained by subtracting the transmission request amount from the scheduled arrival data amount BFi is used as a credit for each grant period. Data delay time can be kept small.

  In addition, in the case of Assured and Non-Assured, credits are given only once for a plurality of grant periods, so that the maximum threshold value for the requested amount of transmission can be increased. Therefore, even when the number of ONUs or the number of queues is increased, it is possible to prevent the transmission request from being disabled.

  Further, in the case of Best-Effect, if the total value of the request amount B from each ONU is equal to or greater than the bandwidth that can be allocated to the Best-Effort, the request amount B can be obtained in order from the ONU with the smaller request amount. Since the limit is given, it is possible to prevent a problem that the transmission request cannot be made even though the transmission request amount is small. In the fourth embodiment, since credits are calculated by weighted proportional distribution of transmission request amounts, there is a case where unfairness occurs in the bandwidth allocated depending on the buffer size and the line rate on the user side. In the embodiment, such a problem can be solved.

(Sixth embodiment)
The schematic configuration of the OLT in the sixth embodiment of the present invention is different from the schematic configuration of the OLT in the first embodiment shown in FIG. 1 only in that the function of the control frame processing unit is different. Further, the OLT processing procedure in the present embodiment is different from the OLT processing procedure in the fifth embodiment shown in FIG. 16 only in that the credit calculation method in the case of Best-Effect is different. Therefore, detailed description of overlapping configurations, functions, and processing procedures will not be repeated. Note that the reference numeral of the control frame processing unit in the present embodiment is described as 13d.

  The control frame processing unit 13d adds the request amount B when receiving the report frame from the ONU, and if the total value of the request amounts B from all ONUs is less than the bandwidth that can be allocated to the Best-Effort. The requested amount B for each ONU is a credit corresponding to the requested amount A.

  In addition, if the total value of request amount B from all ONUs is equal to or greater than the bandwidth that can be allocated to Best-Effort, the bandwidth that can be allocated to Best-Effort is exceeded in order from the ONU indicated by the Best-Effort allocation pointer. The requested amount B is set as a credit corresponding to the requested amount A within a range, and the requested amount B is subtracted from the bandwidth that can be allocated to Best-Effort, and the ONU indicated by the Best-Effort allocation pointer is updated to the next ONU. Note that the Best-Effort allocation pointer is controlled so as to sequentially point to all ONUs connected to the OLT.

  The above processing is sequentially repeated, and when the requested amount B exceeds the bandwidth that can be allocated to Best-Effort, all the remaining bandwidths are set as credits corresponding to the requested amount A for that ONU. The last assigned ONU or the next ONU is the ONU pointed to by the Best-Effort assignment pointer in the next grant period.

  As described above, according to the OLT in the present embodiment, the request amount B is sequentially given to the ONU pointed to by the Best-Effort allocation pointer within a range not exceeding the band that can be allocated to the Best-Effort. As a result, it has become possible to prevent a problem that a transmission request cannot be made even though the transmission request amount is small.

(Seventh embodiment)
The schematic configuration of the OLT in the seventh embodiment of the present invention is different from the schematic configuration of the OLT in the first embodiment shown in FIG. 1 only in that the function of the control frame processing unit is different. Therefore, detailed description of overlapping configurations and functions will not be repeated. Note that the reference numeral of the control frame processing unit in the present embodiment will be described as 13e.

  FIG. 17 is a flowchart for explaining an OLT processing procedure according to the seventh embodiment of the present invention. First, when the control frame processing unit 13e receives a report frame from the ONU received by the receiving unit 11 (S101), the control frame processing unit 13e calculates the permitted transmission amount of Fixed, Assured, and Non-Assured (S102). This calculation method is the same as the method described in the fifth embodiment.

  Next, the control frame processing unit 13e calculates Fixed and Assured credits (S103). This calculation method is the same as the method described in the fifth embodiment. Then, the control frame processing unit 13e determines whether each queue of the ONU is active using the queue length for each queue included in the report frame, and updates the contents of the storage table (S104).

  Next, the control frame processing unit 13e determines whether or not report frames have been received from all ONUs (S105). If there is an ONU that has not yet received a report frame (S105, No), the process returns to step S101 to receive a report frame from the ONU.

  When the report frame is received from all the ONUs (S105, Yes), the control frame processing unit 13e determines the arrival time and the permitted transmission amount (Fixed, Assured) of the ONU processed immediately before each ONU from the storage table. , Non-Assured) and the RTT of the ONU (S106), and calculates and adds Non-Assured credits (S107). The non-assured credit calculation method is the same as the method described in the fifth embodiment.

  Next, the control frame processing unit 13e calculates a transmission permission amount of Best-Effort (S108). If the total amount of request amount B included in the report frame from the ONU is equal to or less than the remaining bandwidth BE_TL after allocation to Fixed, Assured, and Non-Assured, the request amount B is sent to each ONU. And

  Further, if the total value of the request amount B included in the report frame from the ONU is equal to or greater than the remaining bandwidth BE_TL and the total value of the request amount A from the ONU is equal to or greater than the remaining bandwidth BE_TL, the sixth embodiment Similarly to the embodiment, in order from the ONU pointed to by the Best-Effort allocation pointer, the request amount A is set as a transmission permission amount within a range not exceeding the remaining band BE_TL, the request amount A is subtracted from the remaining band BE_LT, and the Best-Effort allocation is performed. The ONU indicated by the pointer is updated to the next ONU.

  The above processing is sequentially repeated, and when the request amount A exceeds the remaining bandwidth BE_LT, all the remaining bandwidths for the ONU are set as transmission permission amounts. The last assigned ONU or the next ONU is the ONU pointed to by the Best-Effort assignment pointer in the next grant period.

  Further, if the total value of the request amount B included in the report frame from the ONU is equal to or greater than the remaining bandwidth BE_TL and the total value of the request amount A from the ONU is equal to or less than the remaining bandwidth BE_TL, the relationship of the following equation is established. Have.

Σ (request amount A) ≦ BE_LT <Σ (request amount B) (7)
Here, BE_RL = BE_LT-Σ (request amount A) is defined, and the request amount B is allocated as a transmission permission amount until BE_RL is completely allocated in order from the ONU indicated by the Best-Effort allocation pointer, and the value of the Best-Effort allocation pointer Update. After the BE_LT is completely allocated, the request amount A is allocated as a transmission permission amount to all ONUs after the ONU pointed to by the Best-Effort allocation pointer.

  Note that if the total value of the request amount B included in the report frame from the ONU is equal to or greater than the remaining bandwidth BE_TL and the total value of the request amount A from the ONU is equal to or less than the remaining bandwidth BE_TL, all the ONUs After the request amount A is allocated, the request amount B is allocated as a transmission permission amount instead of the request amount A within a range not exceeding the remaining bandwidth in order from the ONU indicated by the Best-Effort allocation pointer. Then, the last assigned ONU or the next ONU may be the ONU indicated by the Best-Effort assignment pointer in the next grant period.

  Returning to the description of the flowchart shown in FIG. The control frame processing unit 13e calculates the sum of transmission permission amounts of each queue and sets it as the ONU transmission permission amount (S109). Then, the control frame processing unit 13e determines the ONU's current estimated arrival time and the ONU's estimated arrival time and transmission allowance processed immediately before each ONU read from the storage table, and the ONU's RTT. The sending start time is calculated (S110).

  Next, the control frame processing unit 13e calculates a best-effort credit corresponding to the request amount A by the following equation (S111). Α is an appropriate constant of 1 or more, and BB indicates the maximum allocation amount that can be allocated to Best-Effort. Further, BB1 calculated by the following equation is used as a credit for all ONUs.

BB1 = α × max (max (BB, Σ (request amount B)) / number of ONUs,
Maximum MAC frame size) (8)
Next, the control frame processing unit 13e updates the contents of the credit storage table (S112), and determines whether or not calculations have been performed for all ONUs (S113). If there is an ONU that has not been operated (S113, No), the process returns to step S106 and the subsequent processing is repeated.

  If the calculation is performed for all ONUs (S113, Yes), the control frame processing unit 13e transmits the transmission source address (OLT address), transmission destination address (address of the ONU), transmission start time, transmission A grant frame composed of the permitted amount and the credit is created and transferred to the buffer memory 15, and the transmission of the grant frame is instructed during the downlink data frame (S114).

  As described above, according to the OLT in the present embodiment, a common credit BB1 is given to all ONUs, and the total value of the request amount B included in the report frame from the ONU is less than or equal to the remaining bandwidth BE_TL. Since the request amount A or the request amount B is assigned to each ONU as a transmission permission amount depending on whether or not the total amount of the request amount A from the ONU is equal to or less than the remaining bandwidth BE_TL. It became possible to perform bandwidth allocation according to the situation.

  That is, in the fourth embodiment, since the transmission request amount in the next period is predicted for all the queues and credits are allocated, the bandwidth is required when the OLT receives a transmission request that is significantly different from the prediction. In other words, there is a problem in that waste occurs and the cycle time increases. In the present embodiment, these problems can be solved.

  FIG. 18 is a diagram illustrating a best-effort credit allocated to each ONU in the fourth to sixth embodiments of the present invention. The OLT credit allocation method in the seventh embodiment is fundamentally different from the OLT credit allocation method in the fourth to sixth embodiments, and is not shown in FIG.

  FIG. 18A is a diagram showing the amount of transmission requested from each ONU. The ONU 1 notifies the OLT of the total queue length 100, the ONU 2 reports the total queue length 200, and the ONU 3 reports the total queue length 1700 as the transmission request amount. In addition, the credit allocation amount of Best-Effort is 1000.

  FIG. 18B is a diagram showing the allocation of credits of each ONU when the OLT credit allocation method according to the fourth embodiment of the present invention is used. ONU1 is assigned credit 50, ONU2 is assigned credit 100, and ONU3 is assigned credit 850. Therefore, all of the ONUs 1 to 3 cannot transmit data.

  FIG. 18 (c) is a diagram illustrating allocation of credits of each ONU when the OLT credit allocation method according to the fifth embodiment of the present invention is used. A credit 100 is assigned to ONU1, a credit 200 is assigned to ONU2, and a credit 700 is assigned to ONU3. Therefore, ONU1 and ONU2 can send data.

  FIG. 18D is a diagram showing allocation of credits of each ONU when the OLT credit allocation method according to the sixth embodiment of the present invention is used. This is a case where the Best-Effort assignment pointer points to ONU3. Credit 0 is assigned to ONU1, credit 0 is assigned to ONU2, and credit 1000 is assigned to ONU3. Therefore, all of the ONUs 1 to 3 cannot transmit data. However, when the Best-Effort allocation pointer moves to ONU 1 in the next grant period, ONU 1 and ONU 2 can send data if the credit allocatable amount is the same 1000.

(Eighth embodiment)
In the first to seventh embodiments of the present invention, the OLT 1 dynamically changes a credit and notifies the OLT using a grant frame, and an MPCP (Multi-Point Control Protocol) gate frame The explanation is based on the assumption that The eighth to thirteenth embodiments of the present invention define a protocol for sending credits and a frame format.

  Note that the OLT in the eighth embodiment of the present invention notifies credits using an MPCP register frame that is being standardized by IEEE 802.3ah.

  First, ONU discovery processing by OLT will be described with reference to FIG. First, the OLT issues a gate frame for discovery to all ONUs connected to the OLT. This gate frame is periodically issued from the OLT.

  Of the ONUs that have received the gate frame, the ONU that makes a registration request sends a REGISTER_REQUEST frame to the OLT. When the OLT receives the REGISTER_REQUEST frame, the OLT issues a REGISTER frame to the ONU. The credit calculated by the above-described method is inserted into this REGISTER frame.

  Finally, the ONU that has received the REGISTER frame sends REGISTER_ACK to the OLT, whereby the ONU discovery process by the OLT is completed. The credit described above is calculated assuming that the ONU discovered in this way is currently operating.

  FIG. 20 is a diagram for explaining the format of the MPCP register frame. The MPCP register frame includes a transmission destination address (DA) 51, a transmission source address (SA) 52, a protocol type (Type) 53, an operation code (OP) 54, a time stamp (TM) 55, a flag ( 56) and data (Data) 57.

  As described above, since the MPCP register frame is transmitted from the OLT to the ONU at the time of registration of the ONU, it is advantageous to set the initial value of the credit to the ONU.

(Ninth embodiment)
The OLT according to the ninth embodiment of the present invention notifies credits using an OAM (Operations, Administration, and Maintenance) frame that is being standardized by IEEE 802.3ah.

  FIG. 21 is a diagram for explaining a protocol used by the OLT and the ONU in the ninth embodiment of the present invention. This protocol includes a physical (PHY) layer 71, a MAC (Media Access Control) layer 72, and an OAM layer 73. In this protocol, an upper layer 74 may exist on the OAM layer.

  The OAM layer 73 implements functions such as remote failure detection, remote loopback, and link monitoring. The command notification between the OAM 73 of the OLT 1 and the OAM 73 of the ONU 2 is performed by an OAM PDU (Protocol Data Unit).

  FIG. 22 is a diagram for explaining the format of an OAM frame used by the OLT and the ONU in the ninth embodiment of the present invention. The OAM frame indicates a destination address (DA) 51, a source address (SA) 52, a length / protocol type (Length / type) 58, a protocol sub-type (Subtype) 59, and a function type. A code (OAM code) 60 and OAM data 61 are included.

  Credit is a type of management information, but the MPCP gate frame described above is not supposed to notify such management information. On the other hand, since the OAM frame has a function of notifying such management information, it is suitable for notifying a credit.

  In addition, since this protocol does not require an upper layer protocol, the device can be simplified and the cost can be reduced. Furthermore, it is possible to reduce processing performance overhead.

(Tenth embodiment)
The OLT according to the tenth embodiment of the present invention notifies a credit using a Simple Network Management Protocol (SNMP) over a User Datagram Protocol (UDP) / Internet Protocol (IP) packet.

  FIG. 23 is a diagram for explaining a protocol used by the OLT and the ONU in the tenth embodiment of the present invention. This protocol includes a physical layer (PHY) 71, a MAC layer 72, an IP layer 75, a UDP layer 76, and an SNMP layer 77. The SNMP PDU is notified to the SNMP layer 77 via the IP layer 75 and the UDP layer 76.

  The UDP layer 76 is located in a transport layer above the IP layer 75 and provides connectionless communication. In the SNMP layer 77, network management is executed by a manager making a collection / change request for management information to an agent.

  FIG. 24 is a diagram for explaining a format of an SNMP over UDP / IP packet used by the OLT and the ONU in the tenth embodiment of the present invention. The SNMP over UDP / IP packet includes a destination address (DA) 51, a source address (SA) 52, a protocol type (type) 53, an IPH 62 for IP identification, and an UDP identification. UDPH 63 and SNMP data 64 are included.

  The SNMP over UDP / IP packet is widely used in network devices and is a standard for notifying management information, and is therefore suitable for notifying credits. Further, by using the SNMP mechanism, it is possible to easily ensure the interoperability (connection with devices of other companies).

(Eleventh embodiment)
The OLT according to the eleventh embodiment of the present invention notifies a credit using an SNMP over Ethernet (R) packet.

  FIG. 25 is a diagram for explaining a protocol used by the OLT and the ONU in the eleventh embodiment of the present invention. This protocol includes a physical layer (PHY) 71, a MAC layer 72, and an SNMP layer 77. There may be an OAM layer 73 between the MAC layer 72 and the SNMP layer 77.

  FIG. 26 is a diagram for explaining a format of an SNMP over Ethernet (R) packet used by the OLT and the ONU in the eleventh embodiment of the present invention. The SNMP over Ethernet (R) packet includes a transmission destination address (DA) 51, a transmission source address (SA) 52, a protocol type (type) 53, and SNMP data 64.

  The SNMP over Ethernet (R) packet is widely used in network devices and is a standard for notifying management information, and is therefore suitable for notifying credits. Further, by using the SNMP mechanism, it is possible to easily ensure the interoperability (connection with devices of other companies).

  In addition, since this protocol does not require an upper layer protocol, the device can be simplified and the cost can be reduced. Furthermore, it is possible to reduce processing performance overhead.

(Twelfth embodiment)
The OLT according to the twelfth embodiment of the present invention notifies a credit using a CMIP (Common Management Information Protocol) packet.

  FIG. 27 is a diagram for explaining a protocol used by the OLT and the ONU in the twelfth embodiment of the present invention. This protocol includes a physical layer (PHY) 71, a MAC layer 72, an OAM layer 73, an IP layer 75, a UDP layer 76, and a CMIP layer 78. The CMIP PDU is notified to the SNMP layer 77 via the IP layer 75 and the UDP layer 76.

  The CMIP layer 78 is a protocol standardized by ISO (International Organization for Standardization), and is a protocol for realizing CMIS (Common Management Information Service) which is an OSI (Open Systems Interconnection) management service.

  FIG. 28 is a diagram for explaining the format of the CMIP packet used by the OLT and ONU in the twelfth embodiment of the present invention. The CMIP packet includes a transmission destination address (DA) 51, a transmission source address (SA) 52, a protocol type (type) 53, an IPH 62 for IP identification, and CMIP data 67.

  Since the CMIP packet is an international standard for notifying management information, it is suitable for notifying a credit. Therefore, by using the CMIP mechanism, it is possible to easily ensure the mutual connectivity (connection with devices of other companies).

(Thirteenth embodiment)
The OLT according to the thirteenth embodiment of the present invention notifies credits using an IEEE 802.2-compliant LAN (Local Area Network) / MAN (Metropolitan Area Network) management frame.

  FIG. 29 is a diagram for explaining a protocol used by the OLT and the ONU in the thirteenth embodiment of the present invention. This protocol includes a physical layer (PHY) 71, a MAC layer 72, an OAM layer 73, and a CMIP layer 78.

  FIG. 30 is a diagram for explaining the format of the LAN / MAN management frame used by the OLT and ONU in the thirteenth embodiment of the present invention. The LAN / MAN management frame includes a transmission destination address (DA) 51, a transmission source address (SA) 52, a protocol type (type) 53, and LAN / MAN data 68.

  Since the LAN / MAN management frame is a standard for notifying management information, it is suitable for notifying credit.

  In addition, since this protocol does not require an upper layer protocol, the device can be simplified and the cost can be reduced. Furthermore, it is possible to reduce processing performance overhead.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a block diagram which shows schematic structure of OLT in the 1st Embodiment of this invention. 5 is a flowchart for explaining a processing procedure of a control frame processing unit 13; 4 is a diagram illustrating an example of a storage table provided in a control frame processing unit 13. FIG. It is a figure for demonstrating the reference value used when determining whether ONU is active. It is a block diagram which shows schematic structure of ONU in the 2nd Embodiment of this invention. 5 is a flowchart for explaining a processing procedure of a control frame processing unit 23; It is a figure which shows an example of a data length storage table. It is a flowchart for demonstrating the processing procedure of OLT in the 2nd Embodiment of this invention. FIG. 10 is a sequence diagram for explaining how the transmission timing of an uplink data frame is determined when the OLT 1 transmits the i-th grant frame to the ONU 2 by focusing on one ONU 2; It is a figure which shows an example of the centralized band allocation system in the 3rd Embodiment of this invention. It is a flowchart for demonstrating the processing procedure of OLT in Embodiment 3 of this invention. It is a figure which shows an example of the content of the grant frame which OLT in the 4th Embodiment of this invention issues. It is a figure which shows an example of the content of the report frame which ONU issues in the 4th Embodiment of this invention. It is a flowchart for demonstrating the processing procedure of OLT in the 4th Embodiment of this invention. It is a flowchart for demonstrating the process sequence of the control frame process part 23b in ONU in the 4th Embodiment of this invention. It is a flowchart for demonstrating the processing procedure of OLT in the 5th Embodiment of this invention. It is a flowchart for demonstrating the processing procedure of OLT in the 7th Embodiment of this invention. In the 4th-6th embodiment of this invention, it is a figure which shows the credit of the Best-Effort allocated to each ONU. It is a figure for demonstrating the discovery process of ONU by OLT. It is a figure for demonstrating the format of a MPCP register frame. It is a figure for demonstrating the protocol used by OLT and ONU in the 9th Embodiment of this invention. It is a figure for demonstrating the format of the OAM frame used by OLT and ONU in the 9th Embodiment of this invention. It is a figure for demonstrating the protocol used by OLT and ONU in the 10th Embodiment of this invention. It is a figure for demonstrating the format of the SNMP over UDP / IP packet used by OLT and ONU in the 10th Embodiment of this invention. It is a figure for demonstrating the protocol used by OLT and ONU in the 11th Embodiment of this invention. It is a figure for demonstrating the format of the SNMP over Ethernet (R) packet used by OLT and ONU in the 11th Embodiment of this invention. It is a figure for demonstrating the protocol used by OLT and ONU in the 12th Embodiment of this invention. It is a figure for demonstrating the format of the CMIP packet used by OLT and ONU in the 12th Embodiment of this invention. It is a figure for demonstrating the protocol used by OLT and ONU in the 13th Embodiment of this invention. It is a figure for demonstrating the format of the LAN / MAN management frame used by OLT and ONU in the 13th Embodiment of this invention. It is a block diagram which shows schematic structure of the conventional PON system. It is a sequence diagram for demonstrating the operation | movement procedure of the conventional PON system. It is a figure which shows an example of a distributed allocation system. It is a figure for demonstrating the problem in 1st prior art.

Explanation of symbols

  1,101 OLT, 2,102-1 to 102-n ONU, 11, 14, 21, 24 receiving unit, 12, 16, 22, 26 transmitting unit, 13, 23 control frame processing unit, 15, 25 buffer memory, 27 counter, 103-1 to 103-n buffer, 104 transmission path, 105 splitter, 106 grant, 107 report, 108 upstream information frame, 109 upper network, 110 lower network, 111 user terminal.

Claims (18)

An optical subscriber line terminal device that sends a grant in response to a report from an optical subscriber line terminating device,
First receiving means for receiving data and reports from the optical subscriber line termination equipment;
First transmission means for sending data received by the first reception means to an upper network;
The maximum transmission permission amount of each queue is calculated according to the request amount of the queue length of each queue included in the report received by the first receiving means and the bandwidth classification of each queue, and the calculated maximum transmission permission amount is calculated. The output permission amount of each queue is equal to or less than the maximum transmission permission amount of each queue with respect to the transmission request amount of each queue included in the report received by the first receiving means in the next period. Generating means for generating a grant,
Second receiving means for receiving data from the upper network;
Storage means for storing the data received by the second receiving means and the grant generated by the generating means;
And an optical subscriber line terminal station apparatus including second transmission means for transmitting the data and grant stored in the storage means to the optical subscriber line termination apparatus. An optical subscriber line terminal device that sends a grant in response to a report from an optical subscriber line terminating device,
First receiving means for receiving data and reports from the optical subscriber line termination equipment;
First transmission means for sending data received by the first reception means to an upper network;
The maximum transmission permission amount of each queue is calculated according to the request amount of the queue length of each queue included in the report received by the first receiving means and the bandwidth classification of each queue, and the calculated maximum transmission permission amount is calculated. The transmission permission amount of each queue is the maximum transmission permission of each queue with respect to the transmission request amount of each queue included in the report received by the first receiving means in the next period. Generating means for generating a grant so as to be less than or equal to an amount;
Second receiving means for receiving data from the upper network;
Storage means for storing the data received by the second receiving means and the grant generated by the generating means;
And an optical subscriber line terminal station apparatus including second transmission means for transmitting the data and grant stored in the storage means to the optical subscriber line termination apparatus.   The generating means determines whether each queue of the optical subscriber line terminating device is active with reference to a request amount of the queue length of each queue included in the report received by the first receiving means. Then, the maximum transmission permission amount of each queue is calculated according to the information on whether each queue is active and the bandwidth classification of each queue, and the calculated maximum transmission permission amount is notified to the optical subscriber line terminating equipment. The grant is generated so that the transmission permission amount of each queue is equal to or less than the maximum transmission permission amount of each queue with respect to the transmission request amount of each queue included in the report received by the first receiving means in the next period. The optical subscriber line terminal equipment according to claim 1 or 2.   The generation means sets the maximum transmission permission amount to a value obtained by subtracting the transmission request amount from the arrival arrival data amount for each grant period for the fixed queue, and sets the maximum arrival arrival data amount again when the data arrival interval elapses The optical subscriber line terminal apparatus according to any one of claims 1 to 3, wherein the transmission permission amount is set.   The optical subscriber line terminal apparatus according to any one of claims 1 to 4, wherein the generation unit gives a maximum transmission permission amount only once in a plurality of grant periods to the queues of Assured and Non-Assured. If the total value of the transmission request amount suppressed by the maximum allocation value from each optical subscriber line terminating device is equal to or greater than the band that can be allocated to Best-Effort, the generation means generates the transmission request amount in ascending order. Sorting,
When the transmission request amount suppressed by the maximum allocated value is smaller than the average value obtained by dividing the bandwidth that can be allocated to Best-Effort by the number of optical subscriber line terminating devices to which credit has not yet been allocated, The transmission request amount suppressed by the maximum allocation value is defined as the maximum transmission permission amount, and the transmission request amount suppressed by the maximum allocation value is subtracted from the bandwidth that can be allocated to Best-Effort,
When the transmission request amount suppressed by the maximum allocated value is larger than the average value obtained by dividing the bandwidth that can be allocated to Best-Effort by the number of optical subscriber line terminating devices to which credit has not yet been allocated, The optical subscriber line terminal apparatus according to any one of claims 1 to 5, wherein an average value is set as a maximum permitted transmission amount and the average value is subtracted from a band that can be allocated to Best-Effort.   If the total value of the requested amount of transmission suppressed by the maximum allocated value from each optical subscriber line terminating device is equal to or greater than the band that can be allocated to Best-Effort, the generating means is the optical subscriber line indicated by the pointer. In order from the end device, the maximum requested value is determined from the bandwidth that can be allocated to Best-Effort, with the requested amount of transmission suppressed by the maximum allocated value within the range that does not exceed the bandwidth that can be allocated to Best-Effort. 6. The optical subscriber line terminal apparatus according to claim 1, wherein the transmission request amount suppressed in step 1 is subtracted. The generation means has a total transmission request amount suppressed by a maximum allocation value from each optical subscriber line termination device equal to or greater than a band that can be allocated to Best-Effort, and each optical subscriber line termination device. the maximum total transmission permission amount in suppressing et a transmission request amount from that, if more bandwidth can be allocated to the Best-Effort, in order from the optical network device indicated by the pointer, be assigned to Best-Effort The transmission request amount suppressed by the maximum allocation value within a range that does not exceed the bandwidth that can be transmitted is set as the transmission permission amount, and the transmission request amount suppressed by the maximum allocation value is subtracted from the bandwidth that can be allocated to Best-Effort. Item 6. The optical subscriber line terminal device according to any one of Items 1 to 5. The generation means has a total transmission request amount suppressed by a maximum allocation value from each optical subscriber line termination device equal to or greater than a band that can be allocated to Best-Effort, and each optical subscriber line termination device. total suppressed et a transmission request amount at maximum transmission permission amount from that, if less bandwidth can be allocated to the Best-Effort, for a given optical network unit, is suppressed at the maximum assigned value 6. The transmission request amount that is limited to the maximum transmission permission amount is set as the transmission permission amount for another optical subscriber line terminating device after the transmission request amount is set as the transmission permission amount. 2. An optical subscriber line terminal device according to 1.   The optical subscriber line terminal station apparatus according to claim 1, wherein the maximum transmission permission amount is notified using a multipoint control protocol register frame.   The optical subscriber line terminal apparatus according to any one of claims 1 to 9, wherein the maximum transmission permission amount is notified using an operations, administration, and maintenance frame.   The optical subscriber line terminal station according to any one of claims 1 to 9, wherein the maximum transmission permission amount is notified using a simple network management protocol over user datagram protocol / Internet protocol packet. apparatus.   The optical subscriber line terminal apparatus according to claim 1, wherein the maximum transmission permission amount is notified using a simple network management protocol over Ethernet (registered trademark) packet.   The optical subscriber line terminal apparatus according to any one of claims 1 to 9, wherein the maximum transmission permission amount is notified using a common management information protocol packet.   10. The optical subscriber line terminal apparatus according to claim 1, wherein the maximum transmission permission amount is notified using a local area network / metropolitan area network management frame. A bandwidth allocation method in which an optical subscriber line terminal device sends a grant to a report from an optical subscriber line termination device,
The optical subscriber line terminal unit calculates the maximum transmission permission amount of each queue according to the queue length request amount and the queue division of each queue included in the report received from the optical subscriber line termination device. And steps to
The optical subscriber line terminal device notifying the optical subscriber line terminating device of the calculated maximum transmission permission amount;
The optical subscriber line terminal device generates a grant so that a transmission permission amount of each queue is equal to or less than a maximum transmission permission amount of each queue with respect to a transmission request amount of each queue, and the optical subscriber line Transmitting to the terminating device. An optical subscriber line terminal device that sends a grant in response to a report from an optical subscriber line terminating device,
First receiving means for receiving data and reports from the optical subscriber line termination equipment;
First transmission means for sending data received by the first reception means to an upper network;
The maximum transmission permission amount is calculated according to the request amount of the queue length of each queue included in the report received by the first receiving means, and the calculated maximum transmission permission amount is notified to the optical subscriber line terminating device. Generating means for generating a grant so that a transmission permission amount is equal to or less than the maximum transmission permission amount with respect to a transmission request amount of each queue included in the report received by the first reception unit in the next period; ,
Second receiving means for receiving data from the upper network;
Storage means for storing the data received by the second receiving means and the grant generated by the generating means;
And an optical subscriber line terminal station apparatus including second transmission means for transmitting the data and grant stored in the storage means to the optical subscriber line termination apparatus. A bandwidth allocation method in which an optical subscriber line terminal device sends a grant to a report from an optical subscriber line termination device,
The optical subscriber line terminal station device calculating a maximum transmission permission amount according to a request amount of a queue length of each queue included in a report received from the optical subscriber line terminal device;
The optical subscriber line terminal device notifying the calculated maximum transmission permission amount to the optical subscriber line terminating device;
The optical subscriber line terminal device generates a grant so that a transmission permission amount is equal to or less than the maximum transmission permission amount with respect to a transmission request amount of each queue, and transmits the grant to the optical subscriber line termination device And a bandwidth allocation method.

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