JP5366905B2 - Buffer control method and buffer control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote power saving of a PON system by controlling switching of buffers, relating to an ONU equipped with an internal buffer of small capacity and an external buffer of large capacity. <P>SOLUTION: The buffer control method includes: accumulation control processing means 11 which acquires packet information containing at least a packet length and a destination of the packet inputted in an OLT to control accumulation of the packets in a downlink buffer 12 of the OLT; accumulation information management processing means which records and manages the packet information; external buffer triggering state determination processing means 14 which determines whether or not an external buffer of an ONU is in triggering process based on the packet information; and downlink data rate control processing means 15 which, based on the determination result of the external buffer triggering state determination processing means 14, does not adjust output interval of packets to be transmitted to the ONU if the external buffer is not in triggering process, but adjusts the output interval of the packets to be transmitted to the ONU if the external buffer is in triggering process, thus the downlink data rate is limited to a specified value or lower. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a buffer control method and buffer control in a downlink buffer of a first network device that buffers data to be transmitted to the second network device in a network in which the first network device and the second network device are connected. Relates to the device.

  In particular, a PON (Passive Optical Network) to which an OLT (Optical Line Terminal) corresponding to a first network device and an ONU (Optical Network Unit: subscriber side device) corresponding to a second network device are connected. : Passive optical network) In a system, the present invention relates to a buffer control method and a buffer control device for an OLT downlink buffer.

  Downstream buffer of 10G-EPON (10 Gigabit Ethernet (registered trademark) PON) system as a network connecting a first network device having a downlink buffer and a second network device having an internal buffer and an external buffer as a downlink buffer Will be described as an example. In the 10G-EPON system, the first network device corresponds to the OLT, and the second network device corresponds to the ONU. The external buffer is mounted using a memory externally attached to the protocol control LSI, and the internal buffer is mounted using a memory built in the protocol control LSI.

FIG. 8 shows a downstream buffer of the 10G-EPON system.
In FIG. 8, both the OLT and a plurality of ONUs connected to the OLT are provided with a downlink buffer. Downstream 10 Gbit / s data from NNI (Network Node Interface) connected to the upper network is transmitted to the PON section (effective communication speed 8.7 Gbit / s) via the OLT down buffer, and received from the PON section Is output to the UNI (User Network Interface) via the ONU downstream buffer.

  In the UNI, there are cases where the communication speed is the same or high as compared with the PON section, and at a low speed. The high speed is, for example, the case where the UNI communication speed is 10 Gbit / s, and the low speed is, for example, the case where the UNI communication speed is 1 Gbit / s.

  Since an ONU with a low UNI has an output communication speed lower than that of an input, a large-capacity downlink buffer is required. On the other hand, an ONU with a fast UNI can be handled with a small-capacity downlink buffer because the output communication speed is faster or the same as the input. However, in the ONU, since the UNI communication speed varies depending on the user, it is necessary to provide a large-capacity downlink buffer in accordance with the low communication speed.

  An external buffer is generally used for a large-capacity downlink buffer, and an internal buffer is used for a small-capacity downlink buffer. When an external buffer is used, a dedicated control circuit and I / O are required in the protocol control LSI, so that power consumption is larger than that of the internal buffer.

  By the way, in recent years, power saving has been demanded for PON systems, and in particular, it has been demanded to reduce power consumption of ONUs having a larger number of devices than OLTs. The ONU downstream buffer includes both a small-capacity internal buffer and a large-capacity external buffer as downstream buffers, as in Non-Patent Document 1, and a method for the switching control unit to switch these buffers according to the situation is omitted. Effective for power generation. For example, in the case of an ONU, this situation is the amount of buffer storage (the total length of packets stored in the buffer).

The ONU downlink buffer switching control operation will be described with reference to FIG.
(1) If the amount of downstream buffer storage is small, the external buffer is stopped and input data is stored only in the internal buffer.

  (2) If the amount of data stored in the downstream buffer is large and input data cannot be stored using only the internal buffer, the switching control unit issues a start instruction to the external buffer and starts storing in the external buffer.

  (3) When the buffer accumulation amount decreases again from the state of (2), the input data is accumulated in the internal buffer, and when the external buffer becomes empty, the switching control unit issues a stop instruction to the external buffer, and the external buffer Stop the buffer.

  In the process (2), immediately after issuing an activation instruction to the external buffer, the external buffer is in an initialization process (hereinafter referred to as activation process), and data cannot be stored in the external buffer. Therefore, in order to prevent data input during the external buffer activation process from being discarded, the external buffer is accumulated in a dedicated accumulation area (hereinafter referred to as an activation area) during the external buffer activation process. The capacity of this area is a value obtained by the product of the downlink data rate and the startup processing time of the external buffer.

Hiroyuki Serizawa et al., "Examination of OLT buffer control method in power-saving PON", IEICE Society Conference (Sep, 2009)

  In a network device (ONU) having an internal buffer and an external buffer as downlink buffers, the capacity of the activation area in the internal buffer is relatively large. For this reason, it is difficult to reduce the capacity of the internal buffer and the chip area of the protocol control LSI.

  It is an object of the present invention to provide a buffer control method and a buffer control device that can reduce the capacity of an internal buffer startup area by reducing the capacity of an internal buffer of a network device without discarding data. And

  The buffer control method according to the first aspect of the present invention is the data stored in the second network device by connecting the first network device having the downlink buffer and the second network device having the internal buffer and the external buffer as the downlink buffer. A buffer control method in the first network device of the network in which the second network device activates an external buffer when the amount exceeds a threshold and accumulates data in the external buffer after completion of the external buffer activation processing, A storage control processing step for obtaining packet information including at least a destination and a packet length of the packet input to the first network device, and storing the packet in a downlink buffer of the first network device; and recording the packet information The stored information management processing step to be managed and the packet information When the external buffer is not in the startup process based on the determination result of the external buffer startup state determination processing step for determining whether the external buffer of the second network device is in the startup process and the external buffer startup state determination processing step. Does not adjust the output interval of the packet to be transmitted to the second network device, and adjusts the output interval of the packet to be transmitted to the second network device when the external buffer is in the starting process. And a downlink data rate control processing step for limiting the rate to a predetermined value or less.

  In the buffer control method of the first invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the storage control processing step includes the destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and controlling to store the packet in the OLT downlink buffer. The external buffer activation state determination processing step includes the amount of downlink data for each ONU. Calculates the buffer accumulation amount for each ONU from the UNI communication speed information, and if the calculated result exceeds the capacity of the internal buffer of the ONU, it is estimated that the external buffer of the ONU is being activated and measured in advance. Until the startup processing time of the external buffer of the ONU The data rate control processing step requires the downlink data rate to be limited to a certain value or less. The downlink data rate control processing step is configured to keep the downlink data rate constant according to the request of the external buffer activation state determination processing step. Limit to below value.

  In the buffer control method of the first invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the storage control processing step includes the destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and based on the UNI communication speed information, packets addressed to ONUs having a low UNI communication speed and to a plurality of ONUs are buffers for low-speed ONUs In the external buffer activation state determination step, the ONU external buffer of the ONU whose UNI communication speed is low is determined by the packet information. Determines whether the startup process is in progress and The processing step does not limit the downlink data rate to all ONUs when the external buffer is not in the startup process, and when the external buffer is in the startup process, the download of the packet stored in the low-speed ONU destination buffer Limit the data rate below a certain value.

  In the buffer control method of the first invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the storage control processing step includes the destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and controlling to store the packet separately in a downlink buffer for each destination ONU. It is determined whether or not the external buffer of the ONU is being activated, and the downlink data rate control processing step does not limit the downlink data rate to the ONU when the external buffer is not being activated, and the external buffer If the startup process is in progress, the downlink data rate to the ONU It is limited to less than or equal to the value.

  In the buffer control method of the first invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the external buffer activation state determination processing step is notified from the ONU to the OLT. Whether the external buffer of the ONU is being activated is determined based on the activated activation status of the external buffer.

  A buffer control device according to a second aspect of the present invention connects a first network device having a downlink buffer and a second network device having an internal buffer and an external buffer as downlink buffers, and stores data stored in the second network device. A buffer control device in the first network device of the network in which the second network device activates an external buffer when the amount exceeds a threshold and accumulates data in the external buffer after completion of the external buffer activation processing; Storage control processing means for acquiring packet information including at least a destination and a packet length of a packet input to the first network device, and storing the packet in a downlink buffer of the first network device, and recording the packet information The stored information management processing means to manage and the packet information, the second When the external buffer is not in the startup process according to the determination result of the external buffer startup state determination processing means for determining whether or not the external buffer of the network device is in the startup process and the external buffer startup state determination processing means, When the output interval of packets transmitted to the second network device is not adjusted and the external buffer is in the process of starting, the output interval of packets transmitted to the second network device is adjusted, and the downlink data rate is set to a constant value. Downlink data rate control processing means limited to the following.

  In the buffer control device of the second invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the accumulation control processing means is a destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and storing the packet in the OLT downlink buffer. The external buffer activation state determination processing means The buffer accumulation amount for each ONU is calculated from the data amount and the UNI communication speed information, and when the calculation result exceeds the capacity of the internal buffer of the ONU, it is assumed that the external buffer of the ONU is being activated. Until the start-up processing time of the external buffer of the ONU measured in advance The data rate control processing unit is required to limit the downlink data rate to a predetermined value or less, and the downlink data rate control processing unit is configured to keep the downlink data rate constant in response to a request from the external buffer activation state determination processing unit. It is the structure limited to the value or less.

  In the buffer control device of the second invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the accumulation control processing means is a destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and based on the UNI communication speed information, packets addressed to ONUs having a low UNI communication speed and to a plurality of ONUs are buffers for low-speed ONUs Is stored in the high-speed ONU-destination buffer, and the external buffer activation state determination means uses the packet information to determine whether the UNIU communication speed is low. Is configured to determine whether or not the external buffer is being activated. The data rate control processing means does not limit the downlink data rate to all ONUs when the external buffer is not in the startup process, and when the external buffer is in the startup process, the packet accumulated in the low-speed ONU destination buffer The downlink data rate is limited to a certain value or less.

  In the buffer control device of the second invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the accumulation control processing means is a destination ONU of the packet input to the OLT Packet information including at least the packet length and the UNI communication speed information of the ONU, and performing control to divide and store the packet in a downlink buffer for each destination ONU. It is configured to determine whether or not the external buffer of each ONU is being activated based on information, and the downlink data rate control processing means limits the downlink data rate to the ONU when the external buffer is not being activated. If the external buffer is in the process of starting, the downstream data to the ONU It is a configuration that limits the over preparative below a certain value.

  In the buffer control device of the second invention, the first network device is an OLT in the PON system, the second network device is a plurality of ONUs in the PON system, and the downlink data rate control processing means is such that the external buffer is in the startup process When the data addressed to the ONU is output, the number of clock cycles required by the OLT protocol control LSI is recorded, and the time equal to the value obtained by multiplying the number of clock cycles recorded from the start of data output by a predetermined value Until the elapse of time, it is prohibited to output the data addressed to the ONU from the OLT, and the predetermined value is set to a ratio between the communication speed when the downlink data rate is not limited and the communication speed when the downlink data rate is limited, and the OLT It is the product of one clock cycle time of the protocol control LSI.

  In the present invention, since the first network device (OLT) limits the downlink data rate addressed to the ONU to a certain value or less while the second network device (ONU) performs the external buffer activation process, It is possible to reduce the capacity of the internal buffer by reducing the area for starting the internal buffer in the downstream buffer of the ONU. In addition, data that is not output from the OLT while the OLT limits the downlink data rate to a certain value or less is accumulated in the downlink buffer of the OLT, so that no data is lost. In addition, since the period for limiting the downlink data rate to a certain value or less is only until the start-up process of the ONU external buffer is completed, the amount of data stored in the downlink buffer of the OLT is small. An increase in the buffer capacity of the OLT can be suppressed.

  The accumulation operation of the downstream buffer of the ONU and the effect when the present invention is applied will be described with reference to FIG. For the downstream packet received by the ONU, the type of buffer in which the packet is stored in the ONU and the total value of the stored amount are shown. The horizontal axis is time, and the vertical axis is the total accumulated amount.

  When the OLT does not apply the present invention, the downstream data rate does not change while the ONU performs the external buffer activation process, and the accumulation amount increases as shown by the broken line. It cannot be made smaller.

  On the other hand, when the OLT applies the present invention, while the ONU performs the external buffer activation process, the downlink data rate falls below a certain value, and the slope of the accumulation amount is gentle as shown by the solid line. Therefore, the internal buffer activation area can be reduced to reduce the capacity of the internal buffer.

  Further, the downlink data rate is limited to the downlink data addressed to the ONU having a low UNI communication speed that may activate the external buffer, thereby controlling the downlink data rate provided in the OLT. A single circuit may be used, and OLT data output control when the downlink data rate is limited becomes easy.

  Also, the downlink data rate is limited because the data rate is limited only for downlink data to the ONU, which has a low UNI communication speed that may activate the external buffer, and the UNI communication speed is high. It is possible to prevent a delay for downstream data to the ONU.

  Further, it becomes possible to limit the downstream data rate of the ONU whose external buffer is being activated to an arbitrary communication speed.

It is a figure which shows the structural example of the buffer control apparatus of Example 1 of this invention. 5 is a diagram illustrating a configuration example of an external buffer activation state determination processing unit 14. FIG. 6 is a timing chart showing an example of a packet output operation in a downlink data rate control processing unit 15. It is a figure which shows the structural example of the buffer control apparatus of Example 2 of this invention. 10 is a flowchart illustrating an example of a processing procedure of an accumulation control processing unit 11 according to the second embodiment. It is a figure which shows the structural example of the buffer control apparatus of Example 3 of this invention. 14 is a flowchart illustrating an example of a packet output processing procedure addressed to ONU # i in the third embodiment. It is a figure which shows the downstream buffer of 10G-EPON system. It is a figure which shows the example of switching control operation | movement of the downstream buffer of ONU. It is a timing chart which shows the example of buffer accumulation operation of ONU.

  A feature of the present invention is that, in the second network device (ONU) having both an internal buffer and an external buffer as downlink buffers, the second network device (OLT) received by the first network device (OLT) during the startup process. The data addressed to the network device (ONU) is accumulated in the downlink buffer of the first network device (OLT), and the downlink data rate at which the first network device (OLT) transmits to the second network device (ONU) is set. The first network device (OLT) has a function of limiting to a certain value or less.

  Hereinafter, a buffer control example in the OLT downlink buffer in the PON system in which the OLT and the ONU are connected will be described.

FIG. 1 shows a configuration example of a buffer control apparatus according to a first embodiment of the present invention.
In FIG. 1, the buffer control device in the OLT downlink buffer includes an accumulation control processing unit 11, a buffer 12, a packet information management processing unit 13, an external buffer activation state determination processing unit 14, and a downlink data rate control processing unit 15. .

  When the OLT downlink packet is input, the accumulation control processing unit 11 extracts the destination ONU of the packet and acquires the UNI communication speed of the ONU. Further, the packet is stored in the buffer 12 and at the same time, packet information including the destination of the packet, the packet length, the number of packet cycles, and the UNI communication speed of the destination ONU is notified to the packet information management processing unit 13. The packet cycle number is the number of clock cycles required for the OLT protocol control LSI to process the packet. The packet information management processing unit 13 records and manages the packet information. The UNI communication speed information for each ONU is acquired from the ONU by using the OAM frame, for example, and is recorded and managed by the storage control processing unit 11. As other acquisition means, a means using a MAC frame or a means such as embedding in a part of the preamble may be used.

  The packet information management processing unit 13 notifies the external buffer activation state determination processing unit 14 and the downlink data rate control processing unit 15 of the packet information recorded and managed in response to a request from the downlink data rate control processing unit 15.

  The external buffer activation state determination processing unit 14 calculates the buffer accumulation amount from the downlink data amount for each ONU and the UNI communication speed information based on the packet information, and when the calculation result exceeds the internal buffer capacity of the ONU. Estimates that the ONU external buffer is in the process of starting until the pre-measured time for starting the external buffer of the ONU elapses. Further, when the external buffer activation state determination processing unit 14 determines that the external buffers of all ONUs are not being activated, the downlink data rate control processing unit 15 does not adjust the reading interval from the buffer 12 and The packet read from the buffer 12 is output based on the packet information. On the other hand, when the external buffer activation state determination processing unit 14 determines that the external buffer of any ONU is being activated, the read interval from the buffer 12 is adjusted based on the packet information, and the downlink data to the ONU Limit the rate below a certain value.

  Details of the external buffer activation state determination processing unit 14 and the downlink data rate control processing unit 15 will be described below.

FIG. 2 shows a configuration example of the external buffer activation state determination processing unit 14.
In FIG. 2, the external buffer activation state determination processing unit 14 is based on the switching control processing units 141-1 to 141-N for estimating the activation processing state of the external buffer for each ONU and the estimation result of the activation processing state for each ONU. The limit request processing unit 142 is configured to instruct the downlink data rate control processing unit 15 to limit the downlink data rate to a predetermined value or less.

  The external buffer activation state determination processing unit 14 acquires packet information (destination ONU, packet length, UNI communication speed, etc.) for each ONU from the packet information management processing unit 13, and switches corresponding to the destinations ONU # 1 to ONU # N. Notify each of the control processing units 141-1 to 141-N. Each switching control processing unit 141 has the same function as the switching control unit in the downstream buffer of the ONU in FIG. 9, and from each ONU's buffer accumulation amount measurement and the pre-measured external buffer activation processing time, Guess the startup processing status of the external buffer. Specifically, when the buffer accumulation amount exceeds a value that can be accumulated only by the internal buffer of the ONU, it is estimated that the ONU is being activated, and the activation processing time of the ONU external buffer measured in advance is estimated. Until the time elapses, the activation processing flag is set to “1” and the restriction request processing unit 142 is notified. The activation process flag is a flag indicating whether or not the external buffer of the ONU is being activated. When the flag is “1”, the activation process is being performed, and when it is “0”, the activation process is not being performed. The buffer accumulation amount is measured by adding a value obtained by converting the packet length of the input packet to Byte, and adding it to the buffer accumulation amount, and the ONU can output to the UNI per unit time (8 × UNI communication speed [bit / s ] × value obtained in unit time) is obtained by subtracting from the buffer accumulation amount every unit time. The unit time is, for example, one clock cycle time of the OLT protocol control LSI.

  The restriction request processing unit 142 calculates the logical sum of the activation processing flags notified from the switching control processing units 141-1 to 141-N for each ONU, and notifies the downlink data rate control processing unit 15 as a restriction request flag. When the restriction request flag is “1”, it means that any external buffer of each ONU is in the process of starting, and therefore the downlink data rate control processing unit 15 limits the downlink data rate to a certain value or less. Indicates a request. When the restriction request flag is “0”, it means that none of the ONUs are in the process of starting the external buffer, and therefore it is not necessary for the downlink data rate control processing unit 15 to limit the downlink data rate to a certain value or less. It shows that.

FIG. 3 shows an example of a packet output operation in the downlink data rate control processing unit 15.
When the restriction request flag notified from the external buffer activation state determination processing unit 14 is “1”, the downlink data rate control processing unit 15 adjusts the packet reading interval from the buffer 12 to obtain a desired downlink data rate. Get.

  3A is a timing chart showing a case where the restriction request flag is “0”, and FIG. 3B is a timing chart showing a case where the restriction request flag is “1”. In FIG. 3, the horizontal axis is time, and X is the number of packet cycles of output packet # 1. The read permission flag is a flag included in the downlink data rate control processing unit 15. When the flag is “0”, reading of the next packet from the buffer 12 is prohibited, and when it is “1”, reading is permitted.

  When the restriction request flag in FIG. 3A is “0”, if the downlink data rate control processing unit 15 detects that the buffer 12 is not empty (buffer state: 0), the read permission flag is “1”. Confirm whether or not. When the read permission flag is “0”, the process waits until the read permission flag becomes “1”. In FIG. 3A, since the read permission flag is “1”, it is determined that reading is possible, and packet information is acquired from the packet information management processing unit 13. At this time, the acquired packet information is also acquired by the external buffer activation state determination processing unit 14 at the same time. The downlink data rate control processing unit 15 reads out the packet from the buffer 12 and outputs it based on the packet information. At the same time, the downlink data rate control processing unit 15 confirms whether or not the restriction request flag is “1”. In FIG. 3A, since the restriction request flag is “0”, the read permission flag is set to “0” from the start of packet output to the completion of output, and when the output of the packet is completed, the read permission flag is set to “0”. 1 ”.

When the restriction request flag in FIG. 3B is “1”, after the downlink data rate control processing unit 15 acquires the packet information, the packet reading interval from the buffer 12 is adjusted by the following method. Different from 3 (a). The downlink data rate control processing unit 15 obtains the packet information and confirms whether or not the restriction request flag is “1”. In FIG. 3B, since the restriction request flag is “1”, the downlink data rate control processing unit 15 outputs the packet from the buffer 12 based on the value of the packet cycle number X in the acquired packet information. Until the time of X · τ elapses, the read permission flag is set to “0”, and when the time of X · τ elapses, the read permission flag is set to “1”. This makes it possible to limit the downlink data rate to a desired communication speed or less. Τ is the ratio of the communication speed S _normal [bit / s] when the downlink data rate is not limited to the communication speed S _{rate down} [bit / s] when the downlink data rate is limited to one clock of the OLT protocol control LSI. (S _normal / S _{rate down} ) · T _clk obtained by the product of the cycle time T _clk [s].

FIG. 4 shows a configuration example of the buffer control apparatus according to the second embodiment of the present invention.
In FIG. 4, the buffer control apparatus according to the second embodiment includes an accumulation control processing unit 11, a low-speed ONU-addressed buffer 12A, a high-speed ONU-addressed buffer 12B, a packet information management processing unit 13, an external buffer activation state determination processing unit 14, The data rate control processing unit 15 is configured.

  In this embodiment, as the buffer 12 in the OLT downlink buffer, a low-speed ONU-destined buffer 12A for accumulating packets addressed to ONUs having a low UNI communication speed and a plurality of ONUs (hereinafter referred to as low-speed ONU groups); The second embodiment is different from the first embodiment in that it is divided into a high-speed ONU-addressed buffer 12B that accumulates packets addressed to ONUs having a high UNI communication speed, and the accumulation control processing unit 11 performs accumulation control of each packet. Here, the packets addressed to the plurality of ONUs are multicast (or broadcast) packets. Furthermore, the external buffer activation state determination processing unit 14 according to the present embodiment calculates the accumulated amount of packets in the low-speed ONU group, and determines that any of the ONUs belonging to the low-speed ONU group is performing the external buffer activation process. In this case, the downstream data rate control processing unit 15 is requested to limit the downstream data rate to the low-speed ONU group, which is different from the first embodiment. Further, the downlink data rate control processing unit 15 of this embodiment adjusts the packet interval only for the low-speed ONU addressing buffer 12A in response to a request from the external buffer activation state determination processing unit 14, and addresses the high-speed ONU. The second embodiment is different from the first embodiment in that the packet interval is not adjusted for the buffer 12B.

  Details of the accumulation control processing unit 11 and the downlink data rate control processing unit 15 in the second embodiment will be described below. The packet information management processing unit 13 has the same function as in the first embodiment.

(1) Details of Accumulation Control Processing Unit 11 The accumulation control processing unit 11 according to the second embodiment accumulates in the low-speed ONU addressing buffer 12A or the high-speed ONU addressing buffer 12B in accordance with the UNI communication speed at the destination ONU of the input packet. Control.

FIG. 5 illustrates an example of a processing procedure of the accumulation control processing unit 11 according to the second embodiment.
When an OLT downstream packet is input (step D1), the accumulation control processing unit 11 extracts a destination ONU of the packet (step D2), and determines whether the packet is a packet addressed to a plurality of ONUs ( If it is a packet addressed to a single ONU (step D3) (step D3: No), the UNI communication speed of the destination ONU is acquired (step D4). If the acquired communication speed is low (step D5: Yes), the packet is stored in the low-speed ONU addressing buffer 12A (step D7). Conversely, if the acquired communication speed is high (step D5: No), the packet is stored in the high-speed ONU addressing buffer 12B (step D6). If there are a plurality of destination ONUs for the input packet (step D3: Yes), the packet is stored in the low-speed ONU destination buffer 12A (step D7). At this time, the accumulation control processing unit 11 measures the packet length and the number of packet cycles of the packet (step D8), and notifies the packet information management processing unit 13 of packet information including at least the packet length, the destination ONU, and the UNI communication speed. To do.

(2) Details of Downlink Data Rate Control Processing Unit 15 The downlink data rate control processing unit 15 of the second embodiment is directed to the low-speed ONU when the restriction request flag from the external buffer activation state determination processing unit 14 is “1”. The downlink data rate is limited to a certain value or less by adjusting the packet reading interval only for the buffer 12A, and the downlink data rate is not more than a certain value without adjusting the packet reading interval from the high-speed ONU destination buffer 12B. Not limited to. In order to realize the processing, the packet reading from the low-speed ONU addressed buffer 12A when the restriction request flag is “1” is the same as in the first embodiment with the read permission flag in the first embodiment as the low-speed read permission flag. The packet read interval is adjusted. The low-speed read permission flag is a flag included in the downlink data rate control processing unit 15. When “0”, reading of packets from the low-speed ONU-addressed buffer 12A is prohibited, and when “1”, low-speed ONU addressed This flag indicates permission to read packets from the buffer 12A.

  When the restriction request flag is “1” and the low-speed read permission flag is “1”, the downlink data rate control processing unit 15 reads the packet preferentially from the low-speed ONU-addressed buffer 12A, and allows the low-speed read permission. When the flag is “0”, the packet is read from the high-speed ONU addressing buffer 12B. On the contrary, when the restriction request flag is “0”, the packet is read out from the low-speed ONU-addressed buffer 12A or the high-speed ONU-addressed buffer 12B and output in accordance with the following cases (1) to (3).

  (1) If the high-speed ONU-destined buffer 12B is empty, it is checked whether the low-speed ONU-destined buffer 12A is empty. If not, the packet is read from the low-speed ONU-destined buffer 12A and output.

  (2) If the low-speed ONU addressing buffer 12A is empty, it is checked whether the high-speed ONU addressing buffer 12B is empty. If not, the packet is read from the high-speed ONU addressing buffer 12B and output.

  (3) If both the low-speed ONU-addressed buffer 12A and the high-speed ONU-addressed buffer 12B are not empty, select either the low-speed ONU-addressed buffer 12A or the high-speed ONU-addressed buffer 12B according to the read permission. Read the packet from the buffer. The selection method may be arbitrary.

FIG. 6 shows a configuration example of the buffer control apparatus according to the third embodiment of the present invention.
In FIG. 6, the buffer control device according to the third embodiment includes an accumulation control processing unit 11, an ONU # 1 -destined buffer 12-1 to an ONU # N-destined buffer 12-N, and packets Information management processing unit 13, external buffer activation state determination processing unit 14, and downlink data rate control processing units 15-1 to 15-15 for each ONU that individually limit the downlink data rate for each ONU belonging to the low-speed ONU group. -N, composed of a multiplex control processing unit 16 that multiplex-controls each downlink data rate control processing unit 15-1 to 15-N.

Hereinafter, details of each part in Example 3 will be described.
(1) Details of Accumulation Control Processing Unit 11 The accumulation control processing unit 11 according to the third embodiment controls the accumulation of packets for each destination ONU. When an OLT downstream packet is input, the destination ONU of the packet is extracted, and the UNI communication speed of the ONU is acquired. Further, based on the destination ONU, the packet is stored and controlled in the ONU-destined buffer, and at the same time, the packet length and the packet cycle number of the packet are measured, and packet information including at least the packet length, the destination ONU, and the communication speed of the UNI Is notified to the packet information management processing unit 13.

(2) Details of Packet Information Management Processing Unit 13 The packet information management processing unit 13 according to the third embodiment is different from the first embodiment only in that packet information is recorded and managed for each destination ONU.

(3) Details of External Buffer Activation State Determination Processing Unit 14 The external buffer activation state determination processing unit 14 according to the third embodiment does not have the restriction request process according to the first embodiment, and is output from the switching control processing unit provided for each ONU. The difference from the other embodiments is that the processing flag is notified to the downstream data rate control processing unit 15-i of the ONU #i described later.

(4) Downlink data rate control processing units 15-1 to 15-N
The downlink data rate control processing units 15-1 to 15 -N according to the third embodiment correspond to the ONU # 1 destination buffers 12-1 to 12 -ONU according to the activation processing flag for each ONU from the external buffer activation state determination processing unit 14. It differs from the other embodiments in that the reading interval from the #N addressed buffer 12-N is individually adjusted. In order to realize this processing, each ONU downlink data rate control processing unit 15-1 to 15 -N is provided, and the external buffer activation state determination unit 14 sets the activation processing flag for each ONU downlink data rate control processing unit 15. -1 to 15-N are notified. Further, unlike the other embodiments, a multiplex control processing unit 16 that multiplexes the downlink data rate control processing units 15-1 to 15-N provided for each individual ONU is provided.

  When the activation process flag of the ONU #i is “1”, the downlink data rate control processing unit 15-i adjusts the packet reading interval from the ONU # i-addressed buffer 12-i and downloads the downlink data Limit the rate below a certain value. The method for adjusting the packet reading interval is the same as that in the first embodiment, but the restriction request flag in the first embodiment is used as the activation process flag.

FIG. 7 shows an example of a packet output processing procedure addressed to ONU # i in the third embodiment.
The downlink data rate control processing units 15-1 to 15-N and the multiplex control processing unit 16 read and output the packet for each ONU-addressed buffer according to this flowchart. The downlink data rate control processing unit 15-i confirms whether or not the ONU # i-addressed buffer 12-i is empty (step G1), and if not, checks the read permission flag (step G2). When the read permission flag is “0”, wait until it becomes “1”. When the read permission flag is “1”, the multiplex control processing unit 16 reads from the ONU # i-addressed buffer 12-i. Wait until you select (Step G3). Note that the selection method in the multiplex control processing unit 16 may be arbitrary.

  When the multiplex control processing unit 16 selects reading from the ONU # i-addressed buffer 12-i, the packet information management processing unit 13 transmits the packet information of the packets stored in the ONU # i-addressed buffer 12-i. Acquired (step G4), and reads the packet from the ONU # i-addressed buffer 12-i based on the packet information (step G5). If read permission is not given, the process waits until it is given. The processing in steps G4 and G5 is the same as that in the first embodiment.

  The external buffer activation state determination processing unit 14 according to the fourth embodiment is characterized by not including the switching control processing units 141-1 to 141-N for estimating the activation processing state of the external buffer for each ONU according to the first embodiment.

  In this embodiment, each ONU notifies the OLT of the startup processing state of the external buffer, and the OLT limits the downlink data rate based on the notification result. As a means for notifying the activation processing state of the external buffer, there is a means for each ONU to notify the OLT using, for example, an MPCP frame. As other notification means, there are means for using a MAC frame other than the MPCP frame and means for embedding in a part of the preamble. When the notification result from the ONU indicates that the external buffer is being activated, the activation process flag of the ONU is set to “1”. When the activation process is not being activated, the activation process flag of the ONU is set to “0”. The activation request flag is notified to the restriction request processing unit 142. As in the first embodiment, the restriction request processing unit 142 calculates the logical sum of the activation processing flags for each ONU and notifies the downlink data rate control processing unit 15 as a restriction request flag.

DESCRIPTION OF SYMBOLS 11 Accumulation control processing part 12 Buffer 12A Buffer for low-speed ONU 12B Buffer for high-speed ONU 13 Packet information management processing part 14 External buffer activation state determination processing part 141 Switching control processing part 142 Restriction request processing part 15 Downlink data rate control processing part 16 Multiple control processing unit

Claims (10)

A first network device having a downlink buffer is connected to a second network device having an internal buffer and an external buffer as a downlink buffer, and when the amount of data stored in the second network device exceeds a threshold, the first network device A buffer control method in the first network device of the network in which the network device of 2 activates the external buffer and accumulates data in the external buffer after the start-up processing of the external buffer is completed,
A storage control processing step for acquiring packet information including at least a destination and a packet length of a packet input to the first network device, and performing control for storing the packet in a downlink buffer of the first network device;
Accumulated information management processing step for recording and managing the packet information;
An external buffer activation state determination processing step for determining whether or not the external buffer of the second network device is being activated based on the packet information;
If the external buffer is not in the startup process according to the determination result in the external buffer activation state determination process step, the external buffer is in the startup process without adjusting the output interval of packets to be transmitted to the second network device. A downlink data rate control processing step for adjusting the output interval of packets to be transmitted to the second network device and limiting the downlink data rate to a predetermined value or less. . The buffer control method according to claim 1,
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The accumulation control processing step obtains packet information including at least the destination ONU and the packet length of the packet input to the OLT and the UNI communication speed information of the ONU, and performs control to accumulate the packet in the downlink buffer of the OLT. ,
The external buffer activation state determination processing step calculates the buffer accumulation amount for each ONU from the downlink data amount for each ONU and the UNI communication speed information, and if the calculation result exceeds the capacity of the internal buffer of the ONU, The downlink data rate is constant for the downlink data rate control processing step until the ONU external buffer is estimated to be in the startup process and the ONU external buffer startup process time measured in advance has elapsed. It is a configuration that requires limiting to below the value,
The downlink data rate control processing step limits the downlink data rate to a predetermined value or less in response to a request from the external buffer activation state determination processing step. The buffer control method according to claim 1,
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The storage control processing step obtains packet information including at least the destination ONU and the packet length of the packet input to the OLT and the UNI communication speed information of the ONU, and the UNI communication speed is determined based on the UNI communication speed information. Controls storing packets addressed to low-speed ONUs and multiple ONUs in low-speed ONU-addressed buffers, and storing packets addressed to ONUs with high UNI communication speeds in high-speed ONU-addressed buffers,
The external buffer activation state determination step determines whether or not an ONU external buffer having a low UNI communication speed is being activated based on the packet information.
The downlink data rate control processing step does not limit the downlink data rate to all ONUs when the external buffer is not being activated, and is directed to the low-speed ONU when the external buffer is being activated. A buffer control method characterized by limiting a downlink data rate of packets stored in a buffer to a predetermined value or less. The buffer control method according to claim 1,
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The storage control processing step acquires packet information including at least the destination ONU and the packet length of the packet input to the OLT and the UNI communication speed information of the ONU, and stores the packet by dividing it into a downlink buffer for each destination ONU. Control
The external buffer activation state determination step determines whether or not an external buffer of each ONU is being activated based on the packet information,
The downlink data rate control processing step does not limit the downlink data rate to the ONU when the external buffer is not being activated, and the downlink data to the ONU when the external buffer is being activated. A buffer control method characterized by limiting the rate to a certain value or less. The buffer control method according to claim 1,
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The external buffer activation state determination processing step determines whether or not the external buffer of the ONU is being activated based on the activation process state of the external buffer notified from the ONU to the OLT. To control the buffer. A first network device having a downlink buffer is connected to a second network device having an internal buffer and an external buffer as a downlink buffer, and when the amount of data stored in the second network device exceeds a threshold, the first network device A buffer control device in a first network device of the network in which the network device of 2 activates the external buffer and stores data in the external buffer after completion of the activation processing of the external buffer;
Storage control processing means for obtaining packet information including at least a destination and a packet length of a packet input to the first network device, and performing control for storing the packet in a downlink buffer of the first network device;
Accumulated information management processing means for recording and managing the packet information;
External buffer activation state determination processing means for determining whether or not the external buffer of the second network device is being activated based on the packet information;
If the external buffer is not in the startup process according to the determination result of the external buffer activation state determination processing means, the output interval of packets to be transmitted to the second network device is not adjusted, and the external buffer is in the startup process. If so, a buffer control comprising: a downlink data rate control processing unit that adjusts an output interval of packets to be transmitted to the second network device and limits a downlink data rate to a predetermined value or less. apparatus. The buffer control device according to claim 6.
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The accumulation control processing unit obtains packet information including at least the destination ONU and the packet length of the packet input to the OLT and the UNI communication speed information of the ONU, and performs control to accumulate the packet in the downlink buffer of the OLT. Configuration,
The external buffer activation state determination processing means calculates the buffer accumulation amount for each ONU from the downlink data amount for each ONU and the UNI communication speed information, and if the calculation result exceeds the capacity of the internal buffer of the ONU, The downlink data rate is fixed to the downlink data rate control processing means until the ONU external buffer is estimated to be in the startup process and the ONU external buffer startup process time measured in advance has elapsed. It is a configuration that requires limiting to below the value,
The buffer data control apparatus, wherein the downlink data rate control processing means is configured to limit a downlink data rate to a predetermined value or less in response to a request from the external buffer activation state determination processing means. The buffer control device according to claim 6.
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The storage control processing means obtains packet information including at least the destination ONU of the packet input to the OLT, the packet length, and the UNI communication speed information of the ONU, and the UNI communication speed is determined based on the UNI communication speed information. It is configured to store packets addressed to low-speed ONUs and multiple ONUs in a buffer for low-speed ONUs, and to store packets addressed to ONUs having a high UNI communication speed in a buffer for high-speed ONUs.
The external buffer activation state determination means is configured to determine whether or not an ONU external buffer having a low UNI communication speed is being activated based on the packet information.
The downlink data rate control processing means does not limit the downlink data rate to all ONUs when the external buffer is not being activated, and is directed to the low-speed ONU when the external buffer is being activated. A buffer control device characterized by being configured to limit a downlink data rate of packets accumulated in a buffer to a predetermined value or less. The buffer control device according to claim 6.
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The accumulation control processing means acquires packet information including at least the destination ONU and the packet length of the packet input to the OLT and the UNI communication speed information of the ONU, and accumulates the packet in a downlink buffer for each destination ONU. It is a configuration that performs control,
The external buffer activation state determination means is configured to determine whether or not the external buffer of each ONU is being activated based on the packet information,
The downlink data rate control processing means does not limit the downlink data rate to the ONU when the external buffer is not being activated, and the downlink data rate to the ONU when the external buffer is being activated. A buffer control device characterized in that the rate is limited to a certain value or less. The buffer control device according to claim 6.
The first network device is an OLT in the PON system, and the second network device is a plurality of ONUs in the PON system;
The downlink data rate control processing means records the number of clock cycles required by the OLT protocol control LSI when the external buffer outputs data addressed to the ONU being activated, and records from the start of output of the data Until the time equal to the value obtained by multiplying the number of clock cycles multiplied by a predetermined value elapses, it is prohibited to output data addressed to the ONU from the OLT, and the predetermined value is not limited to the downlink data rate. A buffer control device comprising: a product of a ratio of a communication speed at a time and a communication speed when a downlink data rate is limited to one clock cycle time of the protocol control LSI of the OLT.

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