JP5655739B2 - OPTICAL LINE UNIT, OPTICAL ACCESS TERMINING DEVICE, AND COMMUNICATION CONTROL METHOD - Google Patents

Description

  The present invention relates to an optical line unit, an optical access termination device, and a communication control method, and more particularly, an optical line unit, an optical access termination device, and The present invention relates to a communication control method.

  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, devices capable of broadband access such as ADSL (Asymmetric Digital Subscriber Line) and FTTH (Fiber To The Home) are rapidly spreading.

  In IEEE Std 802.3ah (registered trademark) -2004 (non-patent document 1), a plurality of home side devices (ONU: Optical Network Unit) share an optical communication line, and a station side device (OLT: Optical Line Terminal). One method of a passive optical network (PON), which is a medium-sharing communication that performs data transmission with the network, is disclosed. That is, EPON (Ethernet (registered trademark) PON) in which all information is communicated in the form of an Ethernet (registered trademark) frame, including user information passing through the PON and control information for managing and operating the PON, and EPON An access control protocol (MPCP (Multi-Point Control Protocol)) and an OAM (Operations Administration and Maintenance) protocol are defined. By exchanging MPCP frames between the station side device and the home side device, the home side device joins and leaves, and uplink access multiplexing control is performed. Non-Patent Document 1 describes a registration method for a new home device, a report indicating a bandwidth allocation request, and a gate indicating a transmission instruction using an MPCP message.

  In addition, IEEE 802.3av (registered trademark) -2009 is standardized as the next generation technology of GE-PON (Giga Bit Ethernet (registered trademark) Passive Optical Network), which is an EPON realizing a communication speed of 1 gigabit / second. Even in the 10 G-EPON, that is, the EPON corresponding to a communication speed of 10 gigabits / second, the access control protocol is premised on MPCP.

  By the way, in general, in a network service for business, in order to provide a high quality service, it is essential to make a system redundant (redundant). Also, a highly reliable system can be provided by using a duplex system in an audio / video distribution service. In the redundant system, a redundant configuration is adopted in which each of the devices, components, and network has an active system and a standby system as required. When a failure occurs in a part of the operating system, it is possible to make the system stop time due to the failure as short as possible by performing redundant switching from the active system to the standby system.

  Even if a failure has not become apparent, the module may be replaced proactively in consideration of the deterioration tendency of characteristics, the life of parts, and the like. If the system has a redundant configuration for the module, it is possible to shorten the system stop time due to such maintenance work as much as possible.

  Here, a PON system in which the service node interface (SNI) from the station side device to the host network is duplicated is being studied. As an example of such a PON system, for example, Japanese Unexamined Patent Application Publication No. 2009-284179 (Patent Document 1) discloses the following technique. In other words, the optical access termination device includes a plurality of optical transmission / reception means for mutually converting electrical signals and optical signals, a plurality of PON protocol termination means for inserting and extracting PON control protocol information, and a plurality for connection to a higher level network. Service node interface. The optical access termination device further includes link monitoring means for monitoring normality / abnormality of communication related to the plurality of service node interfaces. A first electric circuit is disposed in an upstream signal path between the plurality of optical transmission / reception means and the plurality of PON protocol termination means. When the communication related to the plurality of service node interfaces is normal, the first electric circuit outputs an upstream signal input from each optical transmission / reception means to the PON protocol termination means corresponding to the optical transmission / reception means. . The first electrical circuit corresponds to an upstream signal input from an optical transmission / reception unit corresponding to an abnormal side and a normal side when communication related to any of the plurality of service node interfaces becomes abnormal. One of the uplink signals input from the optical transmission / reception means is dynamically selected and output to the PON protocol termination means corresponding to the normal side. In the first electric circuit, an upstream signal is temporarily stored in a buffer provided for each optical transmission / reception means, and then output to any PON protocol termination means.

IEEE Std 802.3ah (registered trademark) -2004

JP 2010-147801 A

  However, in the technique described in Patent Document 1, when traffic congestion occurs in the upper network, a frame loss occurs even though the frame storage buffer provided in the station-side apparatus is empty.

  The present invention has been made to solve the above-described problems, and its purpose is to effectively suppress loss of communication signals to be transmitted to the upper network even when traffic congestion occurs in the upper network. An optical line unit, an optical access termination device, and a communication control method are provided.

  In order to solve the above problems, an optical line unit according to an aspect of the present invention transmits / receives a communication signal to / from one or more home-side devices, and transmits the communication signal received from the home-side device to a plurality of communication paths. A plurality of buffers for storing the communication signal received from the home-side device, provided for each priority of the communication path and the communication signal; Based on the communication path of the transmission destination of the communication signal received from the home-side device and the priority, a reception distribution unit for distributing the communication signal and storing it in the buffer, and a priority of the communication signal And a transmission distribution unit for taking out the communication signal from the buffer and outputting it to the communication path of the transmission destination, and the transmission distribution unit includes the communication route. The communication signal transmission stop request is received from the upper network, and the extraction of the communication signal stored in the buffer corresponding to the communication path indicated by the transmission stop request and the output to the communication path are stopped. .

  With such a configuration, it is possible to suppress discarding of communication signals in the host device on the host network side due to excessive transmission of communication signals from the optical line unit. For example, the communication signal buffer in the host device on the host network side is not empty and the buffer on the optical line unit side has room, but the communication signal is transmitted from the optical line unit. It is possible to prevent the communication signal from being discarded. Therefore, even when traffic congestion occurs in the upper network, loss of communication signals to be transmitted to the upper network can be effectively suppressed. Compared with a configuration in which a buffer is provided for each communication path, and the reception distribution unit distributes communication signals received from the home-side device to each buffer, so that no reception distribution unit is provided and a common buffer is provided in each communication path. Thus, it is possible to prevent a decrease in the throughput of communication signal transmission. That is, since transmission of a communication signal can be controlled for each communication path, when the transmission rate of a communication signal to a certain communication path is suppressed, the transmission rate of the communication signal to another communication path is suppressed. Can be prevented.

  Preferably, the transmission stop request indicates the communication path where transmission of the communication signal should be stopped, and the priority of the communication signal where transmission should be stopped, and the transmission distribution unit includes the transmission stop request indicated by the transmission stop request. The extraction of the communication signal stored in the buffer corresponding to the communication path and the priority and the output to the communication path are stopped.

  With such a configuration, when traffic congestion occurs in the upper network, it is possible to suppress the loss of the communication signal according to the priority of the communication signal in accordance with the transmission stop request from the upper device. That is, since it is possible to perform flow control according to priority, such as stopping transmission only for buffers with low priority, loss of communication signals with high priority can be suppressed.

  Preferably, the transmission distribution unit performs another path selection operation of selecting the communication path different from the communication path corresponding to the buffer and outputting the communication signal extracted from the buffer to the selected communication path. It is possible.

  With such a configuration, when a part of the communication path cannot be used, it is possible to prevent loss of a communication signal whose destination is the unusable communication path. In addition, the configuration in which the transmission path is switched in the transmission distribution unit 22 instead of the reception distribution unit can simplify the configuration by concentrating the parts that perform the distribution process.

  More preferably, when the transmission distribution unit receives the transmission stop request in a state in which the other path selection operation is performed, the transmission corresponding to the communication path indicated by the transmission stop request and the selected transmission path The extraction of the communication signal stored in the buffer corresponding to the communication path and the output to the communication path are stopped.

  With such a configuration, it is possible to monitor the status of communication path availability and change the buffer range to dynamically apply backpressure according to the status. Even when the destination changes, a buffer for stopping the extraction and transmission of the communication signal can be appropriately selected. In addition, when it is desired to configure a configuration in which a communication signal is forcibly transmitted to one communication path due to restrictions of the host device, the output destination of the communication signal can be set.

  In order to solve the above problems, an optical access termination device according to an aspect of the present invention includes a plurality of optical line units for transmitting and receiving communication signals with one or a plurality of home side devices, and the plurality of optical line units. An optical access termination device comprising a concentrator for transmitting the communication signal received from the home side device to a higher-level network, wherein the optical line unit receives the communication signal received from the home side device as a plurality of The data amount of the communication signal that can be output to the concentrator via a communication path and that the optical line unit can receive from each home-side device per predetermined time is determined by the concentrator to the upper network. More than the data amount of the communication signal that can be transmitted per time, the optical line unit is provided for each priority of the communication path and the communication signal, Based on a plurality of buffers for storing the communication signal received from the side device, the communication path of the transmission destination of the communication signal received from the home side device, and the priority, A transmission distribution unit for accumulating in the buffer, and a transmission distribution unit for extracting the communication signal from the buffer based on the priority of the communication signal and outputting it to the communication path of the transmission destination. The unit receives a request to stop transmission of the communication signal to the communication path from the concentrator or the upper network, and extracts the communication signal stored in the buffer corresponding to the communication path indicated by the transmission stop request. And the output to the communication path is stopped.

  With such a configuration, it is possible to suppress discarding of communication signals in the host device on the host network side due to excessive transmission of communication signals from the optical line unit. For example, the communication signal buffer in the host device on the host network side is not empty and the buffer on the optical line unit side has room, but the communication signal is transmitted from the optical line unit. It is possible to prevent the communication signal from being discarded. Therefore, even when traffic congestion occurs in the upper network, loss of communication signals to be transmitted to the upper network can be effectively suppressed. Compared with a configuration in which a buffer is provided for each communication path, and the reception distribution unit distributes communication signals received from the home-side device to each buffer, so that no reception distribution unit is provided and a common buffer is provided in each communication path. Thus, it is possible to prevent a decrease in the throughput of communication signal transmission. That is, since transmission of a communication signal can be controlled for each communication path, when the transmission rate of a communication signal to a certain communication path is suppressed, the transmission rate of the communication signal to another communication path is suppressed. Can be prevented. In general, the total communication bandwidth from each home-side device to the station-side device is often larger than the communication bandwidth from the station-side device to the host network, and each home-side device has one optical line unit. In some cases, the communication bandwidth to the network becomes larger than the communication bandwidth from the station-side device to the host network. As described above, it is possible to suppress the frame loss due to the lack of communication band from the station side device to the higher-level network by the configuration for performing the transmission stop control of the upstream frame by effectively using the buffer in the optical line unit as described above. it can.

  In order to solve the above-described problem, a communication control method according to an aspect of the present invention transmits / receives a communication signal to / from one or more home-side devices, and transmits the communication signal received from the home-side device to a plurality of communication paths. A communication control method in an optical line unit that can be transmitted to a higher-level network via the communication path and the plurality of buffers provided for each priority of the communication signal. Based on the communication path and priority of the transmission destination, the step of distributing and storing the communication signal, taking out the communication signal from the buffer based on the priority of the communication signal, and sending it to the communication path of the transmission destination Receiving the communication signal transmission stop request to the communication path from the upper network, and the communication path indicated by the transmission stop request Corresponding and a step of stopping the output of the extraction and the communication path of accumulated said communication signal in the buffer.

  With such a configuration, it is possible to suppress discarding of communication signals in the host device on the host network side due to excessive transmission of communication signals from the optical line unit. For example, the communication signal buffer in the host device on the host network side is not empty and the buffer on the optical line unit side has room, but the communication signal is transmitted from the optical line unit. It is possible to prevent the communication signal from being discarded. Therefore, even when traffic congestion occurs in the upper network, loss of communication signals to be transmitted to the upper network can be effectively suppressed. Compared with a configuration in which a buffer is provided for each communication path, and the reception distribution unit distributes communication signals received from the home-side device to each buffer, so that no reception distribution unit is provided and a common buffer is provided in each communication path. Thus, it is possible to prevent a decrease in the throughput of communication signal transmission. That is, since transmission of a communication signal can be controlled for each communication path, when the transmission rate of a communication signal to a certain communication path is suppressed, the transmission rate of the communication signal to another communication path is suppressed. Can be prevented.

  According to the present invention, it is possible to effectively suppress loss of a communication signal to be transmitted to an upper network even when traffic congestion occurs in the upper network.

It is a figure which shows schematic structure of the PON system which concerns on embodiment of this invention. It is a figure which shows the structure of OSU in the station side apparatus which concerns on embodiment of this invention. It is a figure which shows the communication path | route between the buffer and SNI port in OSU which concerns on embodiment of this invention. It is a figure which shows matching with the priority which a transmission stop request | requirement shows, and a buffer in OSU which concerns on embodiment of this invention. It is a figure which shows matching with the priority which a transmission stop request | requirement shows, and a buffer in OSU which concerns on embodiment of this invention. It is a figure which shows an example of the frame transmission stop control according to the transmission stop request | requirement in OSU which concerns on embodiment of this invention. It is a figure which shows an example of the frame transmission stop control according to the transmission stop request | requirement in OSU which concerns on embodiment of this invention. It is a figure which shows the buffer of the transmission stop object according to the content of the transmission stop request | requirement in the OSU which concerns on embodiment of this invention, and the use condition of each SNI port. It is a flowchart which shows the operation | movement procedure at the time of OSU which concerns on embodiment of this invention performing frame transmission stop control. It is a flowchart which shows the operation | movement procedure at the time of OSU which concerns on embodiment of this invention performing frame transmission resumption control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration and basic operation]
FIG. 1 is a diagram showing a schematic configuration of a PON system according to an embodiment of the present invention.

  Referring to FIG. 1, a PON system 301 includes a station side device (optical access termination device) 201, m PON lines 1 to m (203-1 to 203-m) that are optical fibers, and m pieces of PON lines. Optical couplers 204-1 to 204-m and a plurality of home-side devices (ONUs) 202 are provided. The station apparatus 201 includes optical line units (hereinafter also referred to as OSUs (Optical Subscriber Units)) 1 to m (12-1 to 12-m) and a concentrator 11. Here, m is an integer of 1 or more. Further, the direction from the ONU to the upper network is referred to as an upstream direction, and the direction from the upper network to the ONU is referred to as a downstream direction.

  In the PON system 301, for example, each PON line corresponds to 10G-EPON which is an EPON that realizes a communication speed of 10 gigabits / second, and the upper network is Ethernet (registered trademark) that realizes a communication speed of 10 gigabits / second. ). Also, for example, ONU registration, withdrawal, bandwidth allocation to the ONU, bandwidth request from the ONU, communication speed switching instruction, and sleep (operation stop) instruction to the ONU are performed by the MPCP frame.

  The station apparatus 201 accommodates a plurality of PON lines corresponding to 10G-EPON. One or a plurality of ONUs are connected to one PON line. The station-side apparatus 201 multiplexes data from these PON lines to the upper network. Further, the station-side device 201 distributes data from the upper network and transmits it to each ONU in each PON line. Further, the station side device 201 allocates the upstream band of the PON line to each ONU.

  More specifically, the station-side apparatus 201 is connected to m PON lines 1 to m, and terminates the m PON lines. Each OSU is provided corresponding to a PON line, and transmits / receives a communication signal including a frame to one or a plurality of ONUs connected to the corresponding PON line. The PON lines 1 to m are connected to the optical couplers 204-1 to 204-m, and are connected to the ONUs 202 through these optical couplers. Each ONU 202 and OSU 12 are connected via a PON line 203 and an optical coupler 204, and transmit / receive optical signals as communication signals to / from each other. In the PON system 301, optical signals from each ONU 202 to the OSU 12 are time-division multiplexed on a common PON line 203.

  The line concentrator 11 transmits the upstream frame received from each ONU via a plurality of OSUs to the upper network. Specifically, the concentrator 11 multiplexes uplink frames from the OSUs 1 to m (12-1 to 12-m) and transmits them to the upper network, and distributes the downlink frames received from the upper network to appropriate OSUs. Perform processing.

  Here, the amount of uplink frame data that the OSU 12 can receive from each ONU 202 per predetermined time is equal to or greater than the amount of uplink frame data that the concentrator 11 can transmit to the upper network per predetermined time.

  For example, the bandwidth of the OSU 12 for receiving the upstream frame from each ONU 202 is 10 Gbit / second, and the bandwidth for transmitting the upstream frame from the concentrator 11 to the upper network is 10 Gbit / second, 20 Gbit / second, 1 Gbit / sec or 2 Gbit / sec.

  In the station side device 201, the SNI is multiplexed. That is, a plurality of SNIs are provided for each OSU for redundancy.

  More specifically, the OSU 12 can transmit / receive a frame to / from one or more ONUs 202 and output an upstream frame received from the ONU 202 to the concentrator 11 via a plurality of communication paths, that is, SNI ports.

  In addition, the OSU 12 includes a buffer provided for each SNI for accumulating frames received from the ONU 202.

  FIG. 2 is a diagram showing the configuration of the OSU in the station side apparatus according to the embodiment of the present invention.

  Referring to FIG. 2, the OSU 12 includes a reception distribution unit 21, buffers A1, A2, B1, and B2, a transmission distribution unit 22, an SNI-A interface unit 23, an SNI-B interface unit 24, and a concentrator. 11, a PON receiver 26, a PON transmitter 27, and a controller 28. The transmission distribution unit 22 includes a frame extraction unit 31, a scheduler 32, a buffer monitoring unit 33, a stop request processing unit 34, and an SNI state monitoring unit 35. Although the OSU 12 includes four buffers and two SNI interface units here, the number of buffers and SNI interface units is not limited to this, and various combinations are possible.

  The PON receiving unit 26 and the PON transmitting unit 27 are connected to one optical fiber that is a corresponding PON line as a starting point on the master station side of the PON line. The PON receiving unit 26 receives an upstream optical signal of a specific wavelength, for example, a 1310 nm band, and converts it into an electrical signal of 10 Gbit / second so that bidirectional communication can be performed with each ONU via this optical fiber. The PON transmission unit 27 converts the downstream frame into a downstream optical signal having a different wavelength. For example, the PON transmission unit 27 converts the downlink control frame received from the control unit 28 into an electrical signal of 10 Gbit / second and converts it into a downstream optical signal in the 1570 nm band.

  Further, the PON receiving unit 26 reconstructs a frame from the converted electrical signal and distributes the frame to the control unit 28 or the reception distributing unit 21 according to the type of the frame. Specifically, the data frame is output to the reception distribution unit 21, and a control frame such as an MPCP report frame is output to the control unit 28.

  In the OSU 12, a buffer for accumulating the upstream frames received from the ONU 202 is provided for each priority of the SNI port and the upstream frame. For example, the OSU 12 includes four buffers A1, A2, B1, and B2 provided for two SNI ports, that is, for each SNI interface unit and for each of two priorities.

  The reception distribution unit 21 analyzes the upstream frame received from the PON reception unit 26 by referring to the header information of the upstream frame, for example, and distributes and outputs to the buffers A1, A2, B1, and B2 based on the analysis result. More specifically, the reception distribution unit 21 distributes the upstream frame based on the SNI port of the transmission destination of the upstream frame received from the ONU 202 and the priority, and stores the upstream frame in the buffers A1, A2, B1, and B2.

  Buffers A 1, A 2, B 1, and B 2 accumulate uplink frames received from reception distribution unit 21.

  The transmission distribution unit 22 extracts the upstream frame from the buffers A1, A2, B1, and B2 based on the priority of the upstream frame, and outputs the upstream frame to the destination SNI interface unit.

  In the transmission distribution unit 22, the frame extraction unit 31 extracts the upstream frames stored in the buffers A1, A2, B1, and B2, distributes them to the SNI-A interface unit 23 or the SNI-B interface unit 24, and outputs them.

  The SNI-A interface unit 23 and the SNI-B interface unit 24 perform predetermined communication processing with the concentrator 11, and output the upstream frame received from the frame takeout unit 31 to the concentrator 11.

  The concentrator 11 performs predetermined communication processing with other devices in the upper network, and outputs the upstream frames received from the SNI-A interface unit 23 and the SNI-B interface unit 24 to the upper network.

  The control unit 28 performs station-side processing relating to control and management of the PON line such as MPCP and OAM. That is, by exchanging MPCP messages and OAM messages with each ONU connected to the PON line, ONU operation including upstream access control including ONU registration, withdrawal and bandwidth allocation, and sleep instruction to the ONU Perform management. The control unit 28 outputs a control frame including various control messages such as an MPCP gate frame to the PON transmission unit 27.

  In the transmission distribution unit 22, the buffer monitoring unit 33 monitors the usage state such as the free capacity of the buffers A 1, A 2, B 1, and B 2, and outputs information indicating the monitoring result to the scheduler 32.

  The stop request processing unit 34 analyzes the transmission stop request received from the concentrating unit 11, and outputs information indicating a buffer to stop transmission of the uplink frame to the scheduler 32.

  The SNI state monitoring unit 35 determines whether or not the line concentrator 11 can communicate with the SNI-A interface unit 23 and the SNI-B interface unit 24, and the SNI-A interface unit 23 and the SNI-B interface unit 24 with the line concentrator. The communication abnormality with the unit 11 is monitored, and information indicating the monitoring result is output to the scheduler 32.

  The scheduler 32 controls upstream frame extraction and distribution by the frame extraction unit 31 based on information received from the buffer monitoring unit 33, the stop request processing unit 34, and the SNI state monitoring unit 35.

  The OSU 12 can stop frame extraction from an arbitrary buffer and output to the SNI interface unit in accordance with a transmission stop request from the concentrator unit 11. For this transmission stop request, a commonly used communication protocol can be used. For example, Priority Flow Control (PFC) conforming to the IEEE 802.1Qbb standard, flow control using a pause control frame conforming to the IEEE 802.3x standard, or the like can be used. Note that the transmission stop request from the line concentrator 11 is not necessarily in a format for designating a specific buffer in the OSU 12. The transmission stop request may be generated in the concentrator 11 or may be generated in another device in the higher level network.

  FIG. 3 is a diagram showing a communication path between the buffer and the SNI port in the OSU according to the embodiment of the present invention.

  Referring to FIG. 3, buffer A1 is a buffer for frames with low priority addressed to SNI port A, and buffer A2 is a buffer for frames with high priority addressed to SNI port A. Further, the buffer B1 is a buffer for frames having a low priority addressed to the SNI port B, and the buffer B2 is a buffer for frames having a high priority addressed to the SNI port B. Here, the SNI port A corresponds to the SNI-A interface unit 23, and the SNI port B corresponds to the SNI-B interface unit 24.

  The reception distribution unit 21 accumulates uplink frames addressed to the SNI port A in the buffers A1 and A2, and accumulates uplink frames addressed to the SNI port B in the buffers B1 and B2.

  The transmission distribution unit 22 normally outputs the frame extracted from the buffers A1 and A2 to the SNI port A. In addition, the transmission distribution unit 22 outputs the frame extracted from the buffers B1 and B2 to the SNI port B at normal times.

  In addition, the transmission distribution unit 22 in the OSU 12 can perform another path selection operation of selecting an SNI port different from the SNI port corresponding to the buffer and outputting the uplink frame extracted from the buffer to the selected SNI port. is there.

  That is, the OSU 12 is a redundant route that outputs an upstream frame to an SNI port different from the normal time, as shown by the broken line arrow in FIG. 3, in order to prevent the upstream communication from being interrupted even if an abnormality occurs in one SNI. have.

  With this redundant path, when one SNI is not used or cannot be used, the upstream frame is collected at the other SNI port.

  Specifically, the transmission distribution unit 22 outputs the accumulated frames of the buffers A1, A2, B1, and B2 to the SNI port B when the SNI port A cannot be used, and the buffer A1 when the SNI port B cannot be used. , A2, B1, and B2 are output to SNI port A.

  4 and 5 are diagrams showing correspondence between the priority indicated by the transmission stop request and the buffer in the OSU according to the embodiment of the present invention.

  The transmission distribution unit 22 receives an upstream frame transmission stop request to the SNI port from the concentrator 11, and extracts the upstream frame stored in the buffer corresponding to the SNI port indicated by the transmission stop request and outputs it to the SNI port. Stop.

  Further, for example, the transmission stop request indicates the SNI port where the transmission of the uplink frame should be stopped and the priority of the uplink frame where the transmission should be stopped. The transmission distribution unit 22 stops the extraction of the upstream frame stored in the buffer corresponding to the SNI port and priority indicated by the transmission stop request and the output to the SNI port.

  Specifically, referring to FIGS. 4 and 5, in the PON system 301, for example, a PFC that can designate eight priorities is used as a transmission stop request from the concentrator 11. In the PFC, a request is made to stop transmission of an uplink frame having a specific priority for a specified period.

  On the other hand, the ONU 12 has four buffers for each SNI port and priority. Therefore, the ONU 12 associates the SNI port and priority with the buffer in order to determine which buffer corresponds to the frame indicated by the transmission stop request. The data is stored in a storage unit (not shown).

  The stop request processing unit 34 indicates that the transmission of the accumulated frame in the buffer A1 is stopped when the SNI port indicated by the transmission stop request received from the concentrator 11 is A and the priority is 0 to 3. Is output to the scheduler 32. The stop request processing unit 34 indicates that the transmission of the accumulated frame in the buffer A2 is stopped when the SNI port indicated by the transmission stop request received from the concentrator 11 is B and the priority is 4 to 7. The indicated information is output to the scheduler 32.

  Further, the stop request processing unit 34 indicates that the transmission of the accumulated frame in the buffer B1 is stopped when the SNI port indicated by the transmission stop request received from the concentrator 11 is B and the priority is 0 to 3. The indicated information is output to the scheduler 32. Further, the stop request processing unit 34 indicates that the transmission of the accumulated frame in the buffer B2 is stopped when the SNI port indicated by the transmission stop request received from the concentrator 11 is B and the priority is 4 to 7. The indicated information is output to the scheduler 32.

  Thus, the priority number X and the buffer number Y for each SNI port do not necessarily have to be associated with 1: 1. That is, the number of priorities specified by the transmission stop request may not match the number of buffers, and the transmission stop request may not indicate the priority as in the pause control frame.

  FIG. 6 is a diagram showing an example of frame transmission stop control according to the transmission stop request in the OSU according to the embodiment of the present invention. FIG. 6 shows control when both the SNI port A and SNI port B systems are usable.

  Referring to FIG. 6, for example, when transmission stop is requested for a frame of priority 0 addressed to SNI port A, transmission distribution unit 22 is directed to SNI port A as shown by a thick frame in FIG. 4. The buffer A1 in which frames corresponding to the priority 0 is stored is set as a transmission stop target, that is, the extraction and output of frames from the buffer are stopped.

  Similarly, for example, when transmission stop is requested for frames of priority 0 and 4 addressed to SNI port B, transmission distribution unit 22 prioritizes addressed to SNI port B as shown by the thick frame in FIG. The buffer B1 in which frames corresponding to the degree 0 are stored and the buffer B2 in which frames corresponding to the priority 4 addressed to the SNI port B are stored are set as transmission stop targets.

  As described above, the configuration in which the priority and the buffer are associated with each other in the stop request processing unit 34 enables flow control according to priority, for example, control for stopping only transmission of a low priority frame or a high priority frame. Become.

  FIG. 7 is a diagram showing an example of frame transmission stop control according to the transmission stop request in the OSU according to the embodiment of the present invention. FIG. 7 shows the control when the SNI port B is unavailable.

  Referring to FIG. 7, transmission distribution unit 22 changes a transmission stop target buffer according to, for example, whether or not an SNI port is available.

  That is, when the transmission distribution unit 22 receives a transmission stop request in a state where another path selection operation is being performed, the buffer corresponding to the SNI port indicated by the transmission stop request and the SNI port selected by the other path selection operation The extraction of the upstream frame stored in the buffer corresponding to the above and the output to the SNI port are stopped.

  Specifically, for example, when transmission stop is requested for a frame of priority 0 addressed to SNI port A, the transmission distribution unit 22 sets the buffer A1 as a transmission stop target as described above.

  However, since the SNI port B cannot be used, the transmission distribution unit 22 is in a state of outputting the accumulated frames of the buffers B1 and B2 to the SNI port A by the other path selection operation. For this reason, the output of the frame of priority 0 to the SNI port A cannot be completely stopped only by stopping the extraction and output of the frame from the buffer A1.

  Therefore, the transmission distribution unit 22 sets the buffer B1 as a transmission stop target in addition to the buffer A1.

  More specifically, the SNI state monitoring unit 35 in the transmission distribution unit 22 monitors the availability of each SNI interface unit, so that the scheduler 32 can dynamically change the transmission stop target buffer. As a result, when the communication between each SNI interface unit and the concentrating unit 11 is abnormal, the communication path of the uplink frame can be switched.

  The transmission distribution unit 22 can also set a transmission stop target buffer in a fixed manner. For example, when the station apparatus 201 does not include the concentrator 11, and the OSU 12 and the host apparatus are directly connected using only one system SNI port, the output destination of each buffer is set to one SNI interface. It is possible to fix to the part.

  FIG. 8 is a diagram showing a transmission stop target buffer according to the content of the transmission stop request and the usage status of each SNI port in the OSU according to the embodiment of the present invention.

  Referring to FIG. 8, when the transmission stop request indicates a frame of priority 0 addressed to SNI port A and both SNI port A and SNI port B are usable, buffer A1 is subject to transmission stop. It becomes. If the transmission stop request indicates a frame of priority 4 addressed to SNI port A, and both SNI port A and SNI port B are usable, buffer A2 is subject to transmission stop. When the transmission stop request indicates a frame of priority 0 addressed to SNI port A, when SNI port A is usable and SNI port B is unusable, buffers A1 and B1 are subject to transmission suspension. Become. When the transmission stop request indicates a frame of priority 4 addressed to SNI port A, when SNI port A is usable and SNI port B is unusable, buffers A2 and B2 are subject to transmission suspension. Become. When the transmission stop request indicates a frame of priority 0 addressed to the SNI port B, and both the SNI port A and the SNI port B are usable, the buffer B1 is a transmission stop target. When the transmission stop request indicates a frame of priority 4 addressed to SNI port B, when SNI port A is unusable and SNI port B is usable, buffers A2 and B2 are subject to transmission suspension. Become.

[Operation]
Next, an operation when the OSU according to the embodiment of the present invention performs frame transmission stop control will be described with reference to the drawings.

  FIG. 9 is a flowchart showing an operation procedure when the OSU according to the embodiment of the present invention performs frame transmission stop control.

  Referring to FIG. 9, first, transmission distribution unit 22 performs a normal frame transmission operation until it receives a transmission stop request from concentrating unit 11 (NO in step S1), and receives a transmission stop request (YES in step S1). ), The usage status of the SNI port is confirmed (step S2).

  When both the SNI port A and the SNI port B are in use (YES in step S2), the transmission distribution unit 22 uses the buffer corresponding to the stop target port and stop target priority indicated by the transmission stop request. Frame transmission stops. When receiving a pause control frame as a transmission stop request, the transmission distribution unit 22 sets all priority buffers corresponding to the stop target ports as transmission stop targets (step S3).

  On the other hand, when one of SNI port A and SNI port B is in use (NO in step S2), transmission distribution unit 22 uses SNI port A and SNI port B and the buffer corresponding to the priority to be stopped. Frame transmission stops. When receiving a pause control frame as a transmission stop request, the transmission distribution unit 22 sets all priority buffers corresponding to each stop target port as transmission stop targets (step S4).

  Next, the transmission distribution unit 22 sets a frame transmission stop time (step S5). After the stop time has elapsed, the transmission distribution unit 22 cancels the transmission stop and restarts frame transmission from the buffer that has been the target of transmission stop.

  The transmission distribution unit 22 may receive a new transmission stop request from the concentration unit 11 while frame transmission from a buffer is stopped, and may newly set another buffer as a transmission stop target. The frame transmission stop time of the buffer may be extended.

  FIG. 10 is a flowchart showing an operation procedure when the OSU according to the embodiment of the present invention performs frame transmission resumption control.

  Referring to FIG. 10, first, transmission distribution unit 22 receives a transmission resumption request from line concentrator 11 in a state where frame transmission from the buffer is stopped (YES in step S11), the usage status of the SNI port. Is confirmed (step S12).

  When both the SNI port A and the SNI port B are in use (YES in step S12), the transmission distribution unit 22 uses the restart target port indicated by the transmission restart request and the buffer corresponding to the restart target priority. Frame transmission is resumed (step S13).

  On the other hand, when one of SNI port A and SNI port B is being used (NO in step S12), transmission distribution unit 22 uses SNI port A and SNI port B and the buffer corresponding to the priority to be resumed. Frame transmission is resumed (step S14).

  By the way, in the technique described in Patent Document 1, when traffic congestion occurs in the upper network, frame loss occurs even though the frame storage buffer provided in the station side device has a space.

  On the other hand, in the OSU according to the embodiment of the present invention, the buffers A1, A2, B1, and B2 are provided for each communication path, that is, the SNI port and the priority of the upstream frame, and the upstream frame received from the ONU 202 is received. accumulate. The reception distribution unit 21 distributes the upstream frames and stores them in the buffers A1, A2, B1, and B2 based on the SNI port that is the transmission destination of the upstream frame received from the ONU 202 and the priority. The transmission distribution unit 22 extracts the upstream frame from the buffers A1, A2, B1, and B2 based on the priority of the upstream frame, and outputs the upstream frame to the transmission destination SNI port. The transmission distribution unit 22 receives a request to stop transmission of an upstream frame to the SNI port from the concentrator 11 or the upper network, extracts the upstream frame stored in the buffer corresponding to the SNI port indicated by the transmission stop request, and SNI. Stops output to the port.

  As described above, the OSU 12 can apply back pressure to an arbitrary buffer in accordance with a transmission stop request for each SNI from an upper apparatus in an OSU having a multiplexed communication path, that is, an SNI. That is, when the OSU 12 extracts an upstream frame from the buffer, the OSU 12 stops the extraction and transmission of the upstream frame from the buffer according to the remaining buffer capacity of the higher-level device that is the transmission destination of the frame.

  With such a configuration, it is possible to suppress frame discard in the host device due to excessive transmission of uplink frames from the OSU 12. For example, an upstream frame is transmitted from the OSU even though the upstream frame buffer in the upper network side has no vacancy, and the OSU side buffer has room, and the upper frame side discards the frame. Can be prevented.

  Therefore, the OSU according to the embodiment of the present invention can effectively suppress loss of communication signals to be transmitted to the upper network even when traffic congestion occurs in the upper network.

  In the OSU according to the embodiment of the present invention, as described above, a buffer is provided for each SNI port, and the reception distribution unit 21 distributes the upstream frame received from the ONU 202 to each buffer. With such a configuration, it is possible to prevent a decrease in frame transmission throughput as compared with a configuration in which the reception distribution unit 21 is not provided and a common buffer is provided in each SNI port. That is, since the transmission of the uplink frame can be controlled for each SNI port, when the transmission rate of the frame to a certain SNI port is suppressed, the transmission rate of the frame to another SNI port is suppressed. Can be prevented.

  Also, with the technique described in Patent Document 1, when traffic congestion occurs in the upper network, frame loss occurs uniformly regardless of the priority of the frame.

  On the other hand, in the OSU according to the embodiment of the present invention, the transmission stop request indicates the SNI port where the transmission of the uplink frame should be stopped and the priority of the uplink frame where the transmission should be stopped. The transmission distribution unit 22 stops the extraction of the upstream frame stored in the buffer corresponding to the SNI port and priority indicated by the transmission stop request and the output to the SNI port.

  With such a configuration, when traffic congestion occurs in the host network, frame loss can be suppressed according to the priority of the frame in accordance with a transmission stop request from the host device. That is, since it is possible to perform flow control according to priority, such as stopping transmission only for buffers with a low priority, loss of frames with a high priority can be suppressed.

  In the OSU according to the embodiment of the present invention, the transmission distribution unit 22 selects an SNI port different from the SNI port corresponding to the buffer, and outputs an upstream frame extracted from the buffer to the selected SNI port. A selection operation can be performed.

  With such a configuration, when a part of the communication path cannot be used, it is possible to prevent loss of an upstream frame whose transmission destination is the unusable communication path. Further, with the configuration in which the communication path switching is performed in the transmission distribution unit 22 instead of the reception distribution unit 21, the configuration can be simplified by concentrating the parts that perform the distribution process.

  Further, in the OSU according to the embodiment of the present invention, when receiving a transmission stop request in a state where another path selection operation is performed, the transmission distribution unit 22 buffers corresponding to the SNI port indicated by the transmission stop request. In addition, the extraction of the upstream frame stored in the buffer corresponding to the SNI port selected by the other path selection operation and the output to the SNI port are stopped.

  With such a configuration, it is possible to monitor the availability status of the SNI port and change the range of buffers to be dynamically back-pressured according to the status. Even if changes, backpressure can be applied to the appropriate buffer. In addition, when it is desired to configure a configuration in which a frame is forcibly transmitted to one communication path due to restrictions of the host device, the output destination of the frame can be set.

  The station apparatus according to the embodiment of the present invention includes one or a plurality of OSUs 12 and a concentrator 11. In the OSU 12, buffers A 1, A 2, B 1, and B 2 are provided for each priority of the SNI port and the upstream frame, and accumulate upstream frames received from the ONU 202. The reception distribution unit 21 distributes the upstream frames and stores them in the buffers A1, A2, B1, and B2 based on the SNI port that is the transmission destination of the upstream frame received from the ONU 202 and the priority. The transmission distribution unit 22 extracts the upstream frame from the buffers A1, A2, B1, and B2 based on the priority of the upstream frame, and outputs the upstream frame to the transmission destination SNI port. The transmission distribution unit 22 receives a request to stop transmission of an upstream frame to the SNI port from the concentrator 11 or the upper network, extracts the upstream frame stored in the buffer corresponding to the SNI port indicated by the transmission stop request, and SNI. Stops output to the port.

  As described above, the OSU 12 can apply back pressure to an arbitrary buffer in accordance with a transmission stop request for each SNI from an upper apparatus in an OSU having a multiplexed communication path, that is, an SNI. That is, when the OSU 12 extracts an upstream frame from the buffer, the OSU 12 stops the extraction and transmission of the upstream frame from the buffer according to the remaining buffer capacity of the higher-level device that is the transmission destination of the frame.

  With such a configuration, it is possible to suppress frame discard in the host device due to excessive transmission of uplink frames from the OSU 12. For example, an upstream frame is transmitted from the OSU even though the upstream frame buffer in the upper network side has no vacancy, and the OSU side buffer has room, and the upper frame side discards the frame. Can be prevented.

  Further, in the station side apparatus according to the embodiment of the present invention, the amount of uplink frame data that the OSU 12 can receive from each ONU 202 per predetermined time can be transmitted by the concentrator 11 to the upper network per predetermined time. It is more than the data amount of the upstream frame.

  In general, the total communication bandwidth from each ONU to the station-side device is often larger than the communication bandwidth from the station-side device to the upper network, and the communication bandwidth from each ONU to one OSU is In some cases, it may be larger than the communication band from the device to the upper network. In the station side apparatus according to the embodiment of the present invention, due to the lack of communication band from the station side apparatus to the upper network as described above, the configuration in which the transmission stop control of the uplink frame is effectively performed by using the buffer in the OSU. Frame loss can be suppressed.

  In the OSU according to the embodiment of the present invention, two SNI ports A and B are provided, and when one of the SNI port A and the SNI port B cannot be used, the transmission distribution unit 22 moves to the other SNI port. Although it is configured to output an upstream frame, the present invention is not limited to this. The OSU 12 may have a configuration in which three or more SNI ports are provided. For example, when three SNI ports are provided in the OSU 12, when a certain SNI port is unavailable, for example, another SNI port is selected and an upstream frame addressed to the unavailable port is output and another SNI port is output. Use the port as usual without selecting it.

  Moreover, although the station side apparatus which concerns on embodiment of this invention was set as the structure provided with the concentrating part 11, it is not limited to this. The concentrator 11 may be provided not on the station side device 201 but on the higher network side. In this case, the transmission stop request is directly transmitted from the upper network to the OSU 12.

  The above embodiment 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.

DESCRIPTION OF SYMBOLS 11 Concentration part 12,12-1-12-m Optical line unit 21 Reception distribution part 22 Transmission distribution part 23 SNI-A interface part 24 SNI-B interface part 26 PON reception part 27 PON transmission part 28 Control part 31 Frame extraction part 32 scheduler 33 buffer monitoring unit 34 stop request processing unit 35 SNI state monitoring unit 201 station side device (optical access termination device)
202 Home unit (ONU)
203-1 to 203-m PON line 204-1 to 204-m optical coupler 301 PON system A1, A2, B1, B2 buffer

Claims (6)

An optical line unit capable of transmitting / receiving a communication signal to / from one or a plurality of home-side devices and transmitting the communication signal received from the home-side device to a host network via a plurality of communication paths,
A plurality of buffers provided for each communication path and priority of the communication signal, for storing the communication signal received from the home device;
A receiving and distributing unit for distributing and storing the communication signal in the buffer based on the communication path of the transmission destination of the communication signal received from the home-side apparatus and the priority;
A transmission distribution unit for taking out the communication signal from the buffer based on the priority of the communication signal and outputting it to the destination communication path;
The transmission distribution unit receives a request to stop transmission of the communication signal to the communication path from the upper network, extracts the communication signal stored in the buffer corresponding to the communication path indicated by the transmission stop request, and An optical line unit that stops output to the communication path. The transmission stop request indicates the communication path to stop transmission of the communication signal, and the priority of the communication signal to stop transmission,
2. The transmission distribution unit according to claim 1, wherein the transmission distribution unit stops extraction of the communication signal stored in the buffer corresponding to the communication path and the priority indicated by the transmission stop request and output to the communication path. Optical line unit.   The transmission distribution unit can perform another path selection operation of selecting the communication path different from the communication path corresponding to the buffer and outputting the communication signal extracted from the buffer to the selected communication path. The optical line unit according to claim 1 or 2, wherein   When the transmission distribution unit receives the transmission stop request in the state of performing the other path selection operation, the transmission distribution unit sets the buffer corresponding to the communication path indicated by the transmission stop request and the communication path being selected. The optical line unit according to claim 3, wherein the extraction of the communication signal stored in the corresponding buffer and the output to the communication path are stopped. A plurality of optical line units for transmitting and receiving communication signals with one or a plurality of home-side devices;
An optical access termination device comprising: a concentrator for transmitting the communication signal received from the home side device to the host network by the plurality of optical line units;
The optical line unit can output the communication signal received from the home-side device to the line concentrator via a plurality of communication paths.
The data amount of the communication signal that the optical line unit can receive from each home-side device per predetermined time is greater than or equal to the data amount of the communication signal that the concentrator can transmit to the upper network per predetermined time. Yes,
The optical line unit is
A plurality of buffers provided for each communication path and priority of the communication signal, for storing the communication signal received from the home device;
A receiving and distributing unit for distributing and storing the communication signal in the buffer based on the communication path of the transmission destination of the communication signal received from the home-side apparatus and the priority;
A transmission distribution unit for taking out the communication signal from the buffer based on the priority of the communication signal and outputting it to the destination communication path;
The transmission distribution unit receives a transmission stop request for the communication signal to the communication path from the concentrator or the upper network, and stores the communication stored in the buffer corresponding to the communication path indicated by the transmission stop request. An optical access termination device for stopping signal extraction and output to the communication path. A communication control method in an optical line unit capable of transmitting / receiving a communication signal to / from one or a plurality of home-side devices and transmitting the communication signal received from the home-side device to a host network via a plurality of communication paths,
The communication signal is distributed to a plurality of buffers provided for each priority of the communication path and the communication signal, based on the communication path of the transmission destination of the communication signal received from the home-side device and the priority. Step to accumulate and
Extracting the communication signal from the buffer based on the priority of the communication signal, and outputting to the communication path of the transmission destination;
Upon receiving a request to stop transmission of the communication signal to the communication path from the upper network, the communication signal stored in the buffer corresponding to the communication path indicated by the transmission stop request is extracted and output to the communication path And a step of stopping the communication.

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