JP2011155442A - Traffic measurement circuit of pon system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a traffic volume for each ONU (Optical Network Unit) by focusing on concentration of traffic of the same ONU in a grant period in a PON (Passive Optical Network) system. <P>SOLUTION: This traffic measurement circuit of the PON system is equipped with: a storage means to store a cumulative traffic volume obtained by accumulating frame lengths of upstream frames for each ONU; an integration/addition means to integrate frame lengths of upstream frames transmitted from the same ONU for each grant period, and add the integration value thereof and the cumulative traffic volume of the ONU read from the storage means; and a control means to perform processes of extracting the frame lengths of the upstream frames, a process of reading, from the storage means, the cumulative traffic volume corresponding to the ONU having transmitted the first upstream frame in the grant period, instructing the integration/addition means to integrate the frame lengths, and writing, in the storage means, the cumulative traffic volume obtained by the integration/addition means when detecting a gap. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a traffic measurement circuit that measures the amount of uplink traffic (communication amount) for each user apparatus in a PON (Passive Optical Network) system.

FIG. 1 shows a configuration example in upstream communication of a PON system.
In FIG. 1, the PON system includes an OLT (Optical Line Terminal: optical subscriber line terminating device) 11 installed in a station and an ONU (Optical Network Unit: optical subscriber line network device) 12 installed in each user's house. And an optical fiber 13 and an optical splitter 14 that connect the OLT 11 and a plurality of n ONUs 12 in a 1: n manner.

  In upstream communication from the ONU to the OLT, each ONU transmits an upstream frame to which an LLID (Logical Link IDentifier: logical link identifier) assigned by the OLT is added, and the upstream frame from each ONU is joined by an optical splitter. Forwarded to OLT. The OLT discriminates and receives from which ONU the uplink frame is transmitted based on the LLID of the uplink frame.

  In addition, the OLT sets a grant period consisting of a transmission start time and a transmission duration as a band allocated to each ONU so that the upstream frame from each ONU does not collide after joining at the optical splitter. Transmit upstream frames in the grant period. This grant period is individually assigned according to the traffic amount of each ONU, and a plurality of uplink frames are transmitted together in the grant period of user 1, for example, as shown in FIG. In addition, a gap period in which no significant data exists is secured as needed between grant periods corresponding to each ONU.

  In such a PON system in which a plurality of users share a transmission path, in order to ensure QoS and fairness among users in the OLT, and to monitor the actual traffic volume and use it for bandwidth allocation, A traffic measurement circuit for measuring the traffic volume is required. Furthermore, in the 10G-PON system, a high-speed traffic measurement circuit that can cope with a transmission rate of 10 Gbps is required.

FIG. 2 shows a configuration example of a conventional traffic measurement circuit (Patent Document 1).
In FIG. 2, the conventional traffic measurement circuit includes a control circuit 21, an adder circuit 22, and a memory 23 for storing a cumulative traffic amount corresponding to a user. Based on the processing procedure shown in FIG. 3, the control circuit 21 identifies the user who is the transmission source of the received frame, calculates the address of the memory 23 corresponding to the user, and stores the calculated address and the read control signal in the memory 23. Output. The memory 23 reads the accumulated traffic amount (initial value is 0) from the address corresponding to the user of the received frame and outputs it to the adder circuit 22. In addition, the control circuit 21 extracts the frame length of the received frame, outputs the extracted frame length to the adder circuit 22, instructs addition with the accumulated traffic amount input from the memory 23, and writes to the memory 23. Output a control signal. The adder circuit 22 adds the frame length of the received frame and the accumulated traffic amount input from the memory 23 and outputs the result to the memory 23 as a new accumulated traffic amount. The memory 23 writes the accumulated traffic amount input from the adding circuit 22 back to the address corresponding to the user of the received frame in response to the write control signal of the control circuit 21.

Japanese Patent No. 2580014

  The conventional traffic measurement circuit is configured to identify the user of the transmission source every time a frame is received, and measure the traffic volume for each user by the procedure of reading the accumulated traffic volume, adding the frame length, and writing the accumulated traffic volume. there were. When such a conventional traffic measurement circuit is applied to the OLT of the PON system shown in FIG. 1, a high-speed operation is required because the communication channel is very high-speed. In particular, with respect to the memory, reading / writing is required once for each of the time corresponding to the shortest frame length, and a very high-speed memory is required. Therefore, there has been a problem that the circuit scale of the traffic measurement circuit becomes large.

  The present invention pays attention to the fact that the traffic of the same ONU is concentrated in the grant period in the PON system, and traffic that can measure the traffic amount for each ONU without using a high-speed memory for a high-speed communication channel. An object is to provide a measurement circuit.

  According to the present invention, an OLT and a plurality of ONUs are connected in a one-to-many manner, and the OLT has a predetermined blank at the boundary between the grant period and the grant period of each ONU, which are a transmission start time and a transmission duration time of an upstream frame transmitted by each ONU. It is provided in a PON system that sets a gap indicating time, continuously transmits an upstream frame in a grant period in which the ONU is set, and forwards the upstream frame transmitted from each ONU to the OLT without colliding with each ONU. In the traffic measurement circuit of the PON system that measures the amount of upstream traffic by accumulating the frame length of the upstream frame, storage means for storing the cumulative traffic amount obtained by accumulating the frame length of the upstream frame for each ONU, and for each grant period, Accumulate the frame length of upstream frames transmitted from the same ONU, and the accumulated value and storage means From the storage means, the summing / adding means for adding the accumulated traffic amount of the ONU read out from the storage means, the processing for extracting the frame length of the upstream frame, and the cumulative traffic volume corresponding to the ONU that transmitted the first upstream frame in the grant period from the storage means A control unit that performs a process of reading, a process of instructing the integration of the frame length to the integration / addition unit, and a process of writing the accumulated traffic amount obtained by the integration / addition unit to the storage unit when a gap is detected.

  In addition, when the control means is performing integration processing on the upstream frame length of the same ONU during the grant period, if the upstream frame of another ONU is received without detecting a gap, the control means -It is good also as a structure which performs the process which writes the accumulated traffic amount obtained by the addition means to a storage means, and transfers to the measurement of the upstream traffic amount with respect to the other ONU.

  The traffic measurement circuit of the PON system of the present invention utilizes the fact that uplink frames are continuously transmitted from the same ONU during the grant period, and reads out the frame length accumulation and storage means of the uplink frame during the grant period. A high-speed memory is used for a high-speed communication channel by taking a two-step procedure that only adds to the cumulative traffic volume and updates the cumulative traffic volume of the storage means when a gap at the boundary of the grant period is detected. The traffic volume for each ONU can be measured without any problem.

It is a figure which shows the structural example in the upstream communication of a PON system. It is a figure which shows the structural example of the conventional traffic measurement circuit. It is a flowchart which shows the process sequence of the control circuit 21 of the conventional traffic measurement circuit. It is a figure which shows the Example structure of the traffic measurement circuit of this invention. It is a flowchart which shows an example of the process sequence of the control circuit 31 of the traffic measurement circuit of this invention.

  FIG. 4 shows an embodiment of the traffic measuring circuit according to the present invention. The traffic measurement circuit of the present embodiment is provided in or near the OLT of the PON system shown in FIG. 1, and when each ONU transmits one to a plurality of frames together in each grant period across the gap period, In this configuration, these frames are sequentially input to measure the traffic amount for each ONU.

  In FIG. 4, the traffic measurement circuit of the present embodiment stores a control circuit 31, an integration circuit 32 for integrating the frame length, an addition circuit 33 for adding the integrated value of the frame length and the accumulated traffic amount, and a cumulative traffic amount corresponding to the user. Configured by the memory 34.

  The control circuit 31 identifies the user who is the transmission source of the received frame, calculates the address of the memory 34 corresponding to the user, and outputs the calculated address and the read control signal to the memory 34. The memory 34 reads the accumulated traffic amount (initial value is 0) from the address corresponding to the user of the received frame and outputs it to the adder circuit 33. In addition, the control circuit 31 extracts the frame length of the received frame and outputs the extracted frame length to the integrating circuit 32. Here, when the control circuit 31 continuously receives frames from the same user, the control circuit 31 outputs the extracted frame length to the integration circuit 32 without accessing the memory 34, and performs the frame length integration process. Only instruct. The integrating circuit 32 integrates the input frame length and outputs the integrated value to the adding circuit 33. The adder circuit 33 adds the integrated value of the frame length of the received frame input from the integration circuit 32 and the accumulated traffic amount input from the memory 34 and outputs the result to the memory 34 as a new accumulated traffic amount.

  In addition, the control circuit 31 outputs a write control signal to the memory 34 when it detects a gap at the boundary of the grant period assigned to each user without receiving a frame during a certain time. The memory 34 writes the accumulated traffic amount input from the adder circuit 33 in accordance with the write control signal of the control circuit 31 back to the address corresponding to the user of the received frame.

  As a result, in a situation where frames are continuously received from the same user during the grant period, the frame length is accumulated by the accumulation circuit 32 and the accumulated traffic amount is added, and the update process of the memory 34 is performed. Absent. That is, by updating the accumulated traffic amount in the memory 34 not at every received frame but at the boundary of the grant period, the traffic amount for each user can be measured without using a high-speed memory.

FIG. 5 shows an example of the processing procedure of the control circuit 31 of the traffic measurement circuit of the present invention.
In FIG. 5, a reception frame is awaited, and it is determined whether or not a frame is received within a certain time (S1). When no frame is received within a certain period of time, it is determined that a gap at the boundary of the grant period assigned to each user has been detected. First, when a frame is received before the gap is detected (S1: Yes), the user who transmitted the received frame is identified (S2) and the frame length of the received frame is extracted (S3). Next, it is determined whether or not the user of the received frame is the same as the user of the previous received frame (S4). As will be described later, since the user information is cleared after writing into the memory, the user of the frame received after detecting the gap and writing into the memory is determined as the first user.

  If the user of the received frame is the first (S4: No), the integrating flag is checked (S5). Since the initial value of the accumulation flag is “F”, here, the address of the memory 34 corresponding to the user of the received frame is calculated (S6), and the memory 34 is controlled to read from the address (S6). S7). The memory 34 reads out the accumulated traffic amount corresponding to the user stored in the address and outputs the accumulated traffic amount to the adding circuit 33. Next, the integration circuit 32 is instructed to clear the integration value (S8), the frame length of the received frame extracted in step S3 is output to the integration circuit 32, and the integration instruction is given and the integration flag is set to “T (S9), and the process for the received frame is terminated.

  On the other hand, if it is determined in step S4 that they are the same user (S4: Yes), it means that the same user's frames are continuously received, and the frame of the received frame is not performed without performing the processing of steps S5 to S8. The length is output to the integration circuit 32 to instruct integration, and the integration flag is set to “T” (S9), and the processing for the received frame is completed. That is, when continuously receiving frames from the same user, the extracted frame lengths are accumulated without accessing the memory 34, and only addition with the accumulated traffic volume is performed.

  If a gap is detected in step S1 (S1: No), the accumulation flag is checked (S10). If it is “T” indicating that accumulation is in progress, the accumulation flag is set to the initial value “F”. (S11), write control is performed on the memory 34, and the user information of the received frame is cleared (S12). At this time, the accumulated traffic amount read from the memory 34 in the process of step S7 and the accumulated value of the frame length accumulated in the integrating circuit 32 in the process of step S9 are added by the adding circuit 33, and a new accumulated traffic amount is obtained. Is output to the memory 34. The memory 34 writes back the accumulated traffic amount input from the adder circuit 33 to the address corresponding to the user of the received frame by writing control, and ends the processing for the received frame.

  If the gap is detected in the process of step S1, but the integrating flag is the initial value “F” in the process of step S10, the process of adding the frame length of the received frame is not performed, and the process ends. .

  On the other hand, if the frame is received before detecting the gap (S1: Yes) and the user of the received frame is the first (S4: No), if the integrating flag is “T” in the process of step S5, Frames from different users have been received one after another before a certain time for detecting the gap. In this case, it is necessary to write back the accumulated traffic amount obtained by adding the integrated value of the frame length to the frame from the previous user to the memory 34. Therefore, if the integrating flag is “T” in the process of step S5, write control is performed on the memory 34 (S13). That is, the cumulative traffic amount for the previous user is written back and the user information is cleared. Then, the address of the memory 34 corresponding to the current user is calculated (S6), and the memory 34 is controlled to read from the address (S7). The same applies hereinafter.

11 OLT (Optical Subscriber Line Termination Equipment)
12 ONU (Optical subscriber line network equipment)
DESCRIPTION OF SYMBOLS 13 Optical fiber 14 Optical splitter 21 Control circuit 22 Adder circuit 23 Memory 31 Control circuit 32 Accumulator circuit 33 Adder circuit 34 Memory

Claims (2)

The OLT is connected in a one-to-many relationship with a plurality of ONUs, and the OLT has a gap indicating a predetermined blank time at the boundary between the grant period and the grant period of each ONU. Is provided in a PON system that continuously transmits an upstream frame in a grant period in which the ONU is set, and forwards the upstream frame transmitted from each ONU to the OLT without colliding with the upstream frame of each ONU. In the traffic measurement circuit that measures the amount of upstream traffic by accumulating the frame length of
Storage means for storing a cumulative traffic amount obtained by accumulating the frame length of the upstream frame for each ONU;
Accumulation / addition means for accumulating the frame lengths of upstream frames transmitted from the same ONU for each grant period, and adding the accumulated value and the cumulative traffic amount of the ONU read from the storage means;
Processing for extracting the frame length of the upstream frame, processing for reading the accumulated traffic amount corresponding to the ONU that transmitted the first upstream frame in the grant period, and instructing the integration / addition unit to integrate the frame length PON system traffic measurement circuit, comprising: processing; and control means for performing processing for writing the accumulated traffic amount obtained by the integrating / adding means into the storage means when the gap is detected. In the traffic measurement circuit of the PON system according to claim 1,
When the control means is performing integration processing of upstream frame lengths of the same ONU in the grant period, if an upstream frame of another ONU is received without detecting the gap, at that time A traffic measurement circuit for a PON system that performs a process of writing the accumulated traffic amount obtained by the integrating / adding means to the storage means and shifts to the measurement of the upstream traffic amount for the other ONU .

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