JP4709020B2 - Software transfer method - Google Patents

Description

  The present invention relates to a software transfer method, and more specifically, a software transfer method from a station side device OLT (Optical Line Terminal) in a passive optical network PON (Passive Optical Network) to each subscriber connection device ONT (Optical Network Terminal). About.

  As one of access networks to a wide area network such as the Internet, there is a passive optical network (PON) system in which a plurality of subscribers can share an optical fiber. The PON system consists of a plurality of subscriber connection devices (access nodes) ONT each connected to a subscriber terminal, and a station side device (access node termination device) OLT connected to these devices by optical fiber, An optical fiber connected to the station side device OLT and a plurality of branch line optical fibers connected to each subscriber connection device ONT are coupled by an optical coupler (star coupler), and the optical fiber is connected between the optical coupler and the station side device OLT. By sharing the optical fiber with a plurality of subscriber terminals, it is possible to significantly reduce the installation cost of the optical fiber.

  The PON system includes B-PON (Broadband PON) that transmits information using fixed-length ATM cells in the optical fiber section (PON section), G-PON (Gigabit PON) that enables high-speed data transfer in the Gigabit class, and Ethernet. There is a GE-PON (Giga-Ethernet PON) suitable for (registered trademark) services. In G-PON (GE-PON), variable length frames can be transferred. Note that ITU-T recommendations regarding G-PON include, for example, Non-Patent Document 1 to Non-Patent Document 4.

  In the PON system, a transmission frame (downstream frame) from the OLT is branched to all branch optical fibers by an optical coupler. Each subscriber connection device ONT determines a frame to be received according to destination information included in the received frame. A transmission frame (upstream frame) from each ONT reaches the OLT in a state of being multiplexed by the optical coupler. In this case, each ONT outputs a transmission frame to the branch optical fiber in a time zone specified in advance from the OLT so that frames transmitted from a plurality of ONTs do not collide on the optical fiber.

  Data transmitted and received between the OLT and each ONT includes client data (for example, telephone, video, text data, etc.) handled by the subscriber terminal and ONT monitoring control data. Since the ONT monitoring control data is transmitted to the PON section via the ONT management control interface OMCI (ONT Management Control Interface) logically existing in the OLT as described later, in the following description, the ONT monitoring control data A frame including data is called an OMCI frame. The client data and the OMCI frame are mounted on the payload portion of the downstream frame unique to the PON section and transmitted to each ONT.

  FIG. 2 shows a format of a client frame 50 (hereinafter referred to as a GEM (G-PON Encapsulation Mode) client frame) received by each subscriber connection device ONT from the OLT in the G-PON. The GEM client frame 50 includes a 5-byte GEM header 51 and a variable-length GEM payload 52. The GEM header 51 includes a port ID that identifies a destination subscriber connection device. Each subscriber connection device ONT identifies the frame addressed to itself according to the port ID indicated by the GEM header 51 of the received frame, and relays the contents of the GEM payload 52 to the subscriber terminal.

  The port ID includes a port ID that individually designates a subscriber connection device and a multicast port ID that designates all subscriber connection devices connected to the same optical fiber. By applying the multicast port ID, the OLT can simultaneously distribute the payload information of the GEM frame to a plurality of ONTs.

FIG. 3 shows the format of the OMCI frame 60.
The OMCI frame 60 includes a GEM header 61, an OMCI header 62, and a message content field 63. The GEM header 61 includes a port ID that identifies a destination subscriber connection device. Since it is assumed that OMCI message contents are individually transmitted to each access node ONT, the multicast port ID is not defined in the GEM header 61 of the OMCI frame 60.

FIG. 4 shows the format of a GTC (G-PON Transmission Convergence) TC (Transmission Convergence) downstream frame 70 transmitted from the OLT to the ONT in the G-PON.
The GTC TC downstream frame 70 includes a PCBd (Physical Control Block downstream) 71 serving as a header and a GTC payload 72, and has a total length of 38880 bytes. The GEM client frame 50 and the OMCI frame 60 are transmitted to the optical fiber (PON section) in a form mapped to the payload 72 of the GTC TC downstream frame 70.

  The length of the PCBd 71 increases by 8 bytes in proportion to the number of frames mapped to the GTC payload 72. When the number of frames included in the GTC payload 72 is one, the PCBd length is the shortest 38 bytes. The GTC payload 72 has a length obtained by subtracting the PCBd length from 38880 bytes. The OLT converts the GTC TC downstream frame 70 into an optical signal and transmits it to the PON section.

ITU-T G.984.1 “Gigabit-capable Passive Optical Networks (GPON): General characteristics” ITU-T G.984.2 `` Gigabit-capable Passive Optical Networks (GPON): Physical Media Dependent (PMD) layer specification '' ITU-T G.984.3 “Gigabit-capable Passive Optical Networks (GPON): Transmission convergence layer specification” ITU-T G.984.4 `` Gigabit-capable Passive Optical Networks (GPON): ONT management and control interface specification ''

  In the G-PON system, when the ONT software file is transferred (downloaded) from the monitoring control device to each subscriber connection device ONT by remote operation, first, the software file is transferred from the monitoring control device to the station side device OLT. In response to a file transfer instruction from the monitoring control device, the OLT transfers the software file to the ONT.

  Since the software file transfer (download) from the OLT to the ONT corresponds to software maintenance which is a kind of ONT monitoring control, conventionally, the OLT transfers the ONT software to each ONT using an OMCI frame. However, since the payload (message content field 63) of the OMCI frame has a fixed length of 32 bytes, the OLT usually divides the ONT software to be transferred into a plurality of data blocks of 32 bytes length. A plurality of OMCI frames including data blocks are mapped to the GTC TC downstream frame 70 and transferred to the ONT.

  However, a multicast port ID is not defined in the OMCI frame. Therefore, when it is desired to transfer the same software file to a plurality of ONTs simultaneously, the OLT needs to generate a plurality of OMCI frames including ONT individual port IDs in the GEM header for each data block of the ONT software.

  That is, as shown in FIG. 5A, the OLT divides the ONT software (file) D into a plurality of data blocks D1 to Dm having a length of 32 bytes. As shown in FIG. , A plurality (N) of OMCI frames F1 (1) to F1 (n) having different port IDs of the GEM header 61 are generated, and the N-folded OMCI frame is mounted on the GTC TC downstream frame 70 to form a PON section. Had to be sent to.

  However, as shown in FIG. 3, the OMCI frame requires 25 bytes for the GEM header and the OMCI header for a payload length of 32 bytes, so that the overhead is too large for the ONT software transfer frame. There was a problem.

  Also, in the GTC TC downstream frame, the length of the header part (PCBd) 71 increases in proportion to the number of frames mapped to the GTC payload 72, as described with reference to FIG. In the GTC payload 72, a maximum of 597 57-byte OMCI frames can be mounted. In this case, the PCBd 71 is 4806 bytes, which occupies 12% of the entire GTC TC downstream frame. When 597 OMCI frames are mapped to the GTC payload 72, the PCBd 71, the GEM header, and the OMCI header occupy about 51% of the entire GTC TC downstream frame, resulting in very inefficient data transfer. End up.

  Furthermore, in the case of transferring the N-multiplied OMCI frame by the GTC TC downstream frame 70 as described above, when viewed from each ONT, the effective OMCI frame addressed to the own node is only 1 / N of the received frame, In addition, since only 32 bytes of data are extracted from one valid OMCI frame, there is a problem that it takes a long time to download large-capacity software.

  An object of the present invention is to provide an improved software transfer method capable of efficiently transferring a large-capacity ONT software file to a plurality of subscriber connection devices ONT in a G-PON system.

  In order to achieve the above object, according to the software transfer method of the present invention, the station side device OLT divides software to be distributed to the plurality of subscriber connection devices ONT into a plurality of data blocks, and each data block is used as a header portion. Mounted in the payload portion of the client frame including the port ID for multicast, and mounted on the payload portion of the downstream frame unique to the PON section, sent to the optical fiber, and received each downstream frame The ONT stores the data block extracted from the client frame including the multicast port ID in the header portion in the software file memory.

  More specifically, the client frame is a GEM (G-PON Encapsulation Mode) client frame, and the downstream frame transmitted from the OLT to the PON section is a GTC TC downstream frame. In the preferred embodiment of the present invention, the OLT divides the software file to be transferred to the ONT into data blocks up to 38837 bytes long, and in each GTC TC downstream frame payload, a single GEM client for software transfer. Mount the frame.

  According to the present invention, since the payload in the downstream frame in the PON section can be used effectively, the software transfer (download) from the OLT to the ONT can be completed in a short time.

FIG. 1 is a diagram schematically showing an example of a G-PON system to which the present invention is applied.
The G-PON system includes a station side device OLT 10, a plurality of subscriber connection devices ONT 20 (20-1 to 20-n), and a monitoring control device 30. Each ONT 20 is connected to branch optical fibers 41 (41-1 to 41-n) branched from an optical fiber 40 connected to the OLT 10 by an optical coupler 42.

  The OLT 10 includes a first signal processing unit 11 connected to the optical fiber 40 and the wide area network NW1, a control unit 13 connected to the signal processing unit 11 via an ONT management control interface (OMCI) 12, and a control unit. 13 includes a second signal processing unit 14 for communicating with the monitoring control device 30 via the control network NW2, and a memory 15 for storing the ONT software file. The first signal processing unit 11 includes, for example, A transmission time zone allocation function to each ONT, a termination function of a reception frame from the ONT, a transfer function to the wide area network NW1, and a downstream PON frame including a reception frame (packet) from the wide area network NW1 or an ONT monitoring control frame A function of generating (GTC TC downstream frame 70) is provided.

  Each ONT 20 is connected to the signal processing unit 21 connected to the branch optical fiber 41, the control unit 23 connected to the signal processing unit 21 through the ONT management control interface (OMCI) 22, and the signal processing unit 21. A subscriber terminal such as a telephone 24A, a video terminal 24B, a data terminal 24C, and a memory 25 for storing ONT software files.

  The signal processing unit 21 transmits the transmission data from the subscriber terminal to the branch optical fiber in the time zone specified by the OLT, and the GEM client frame or the OMCI frame extracted from the downstream PON frame (GTC TC downstream frame 70). From the port ID indicated by the GEM header, the frame to be received and processed by the own node is identified. The signal processing unit 21 transfers the OMCI frame having its own port ID in the GEM header to the control unit 23, and the GEM client frame having its own port ID in the GEM header extracts the contents of the payload, and the subscriber terminal 24A Output to ~ 24C.

  In the present invention, as will be described later, the OLT 10 divides the ONT software file into a plurality of data blocks, and transmits each data block to the ONT in a GEM client frame including a multicast port ID in the GEM header. When the signal processing unit 21 receives the GEM client frame having the multicast port ID in the GEM header, the signal processing unit 21 transfers it to the control unit 23. The control unit 23 extracts data blocks from the payload of the GEM client frame, stores them one after another in the memory 25, and configures an ONT software file.

  The monitoring control device 30 includes a signal processing unit 31 for communicating with the OLT 10 via the control network NW2, a control unit 33 connected to the signal processing unit 31, an input / output device 34 serving as an operator interface, and ONT software. It comprises a memory 35 for storing files.

  When the operator of the monitoring control device 30 designates the file name from the input / output device 34 and instructs the file transfer to the OLT 10 in the state where the ONT software file is already stored in the memory, the control unit 33 causes the ONT 20 to be transferred from the memory 35. The ONT software file to be downloaded to (20-1 to 20-n) is read, and is transmitted to the control network NW2 through the signal processing unit 31 in a predetermined frame format having an address addressed to the OLT 10.

  When receiving the frame from the control network NW2, the second signal processing unit 14 of the OLT 10 inputs the frame to the control unit 13. The control unit 13 stores the ONT software extracted from the received frame in the memory 15. When the ONT software file has a large capacity, the monitoring control device 30 divides the software file into a plurality of data blocks, and transmits the ONT software file to the OLT 10 in a plurality of frames.

  When the operator of the monitoring control device 30 designates a file transfer to the ONT by specifying the file name and port ID from the input / output device 34, the control unit 33 controls the file transfer instruction control message having an address addressed to the OLT 10. Is transmitted to the control network NW2 via the signal processing unit 31. The control message is transferred to the OLT 10 and input from the second signal processing unit 14 to the control unit 13.

  Upon receiving the control message, the control unit 13 reads out a software file having a designated file name from the memory 15, and generates a GEM client frame including the software file in the payload, as will be described later. Thereafter, the control unit 13 commands the first signal processing unit 11 to transfer the GEM client frame to the ONT via the ONT management control interface (OMCI) 12. The first signal processing unit 11 mounts this GEM client frame on the payload of the GTC TC downstream frame and sends it out to the optical fiber 40.

  When the software file has a large capacity that cannot be transferred by one GEM client frame, the control unit 13 divides the software file into a plurality of data blocks having a predetermined size, and each of the plurality of GEM client frames each including one data block. Generate. When the control message from the monitoring control device 30 instructs the file transfer to the specific ONT, the control unit 13 generates a GEM client frame including the port ID of the specific ONT in the GEM header. When the control message indicates that the file transfer to all ONTs connected to the optical fiber 40 is instructed, the control unit 13 includes the GEM client frame including the multicast port IDs of the ONTs 20-1 to 20-n in the GEM header. Is generated.

In this embodiment, a case where ONT software is multicast to ONTs 20-1 to 20-n will be described.
When the ONT software is transferred to all ONTs connected to the optical fiber 40, the OLT 10 (control unit 13) converts the ONT software (file) D into a plurality of fixed-length data blocks D1 and D2, as shown in FIG. ,... And generates a series of GEM client frames 50 each containing one data block in the GEM payload 52. The last data block Dj is a data block with a fractional byte length. In the preferred embodiment of the present invention, the ONT software is divided into 38837 byte long data blocks D1, D2,.

  When each data block length is 38837 bytes, the GTC payload 72 of the GTC TC downstream frame 70 can be used most efficiently. That is, in the GTC TC downstream frame 70, as the number of frames included in the GTC payload 72 increases, the length of the header part (PCBd) 71 increases by 8 bytes, so the number of frames included in the GTC payload 72 is reduced to one. The GTC payload length can be a maximum value of 38842 bytes.

  If each data block length is 38837 bytes, the length of the GEM client frame including this data block in the payload 52 is equal to the GTC payload length 38842 by adding the 5-byte GEM header 51. In this case, the loss due to the PCBd 71 and the GEM header 51 can be minimized, and the ONT software can be transferred most efficiently in the PON section.

FIG. 7 shows a sequence diagram of software file transfer according to the present invention.
Upon receiving a file transfer command from the operator to the OLT, the monitoring control device 30 (control unit 33) reads the ONT software file designated by this command from the memory 35 and transfers it to the OLT 10 in a predetermined communication message format (SQ1). ). The OLT 10 stores the ONT software file extracted from the received message in the memory 15 (S1), and then returns a reception response to the monitoring control device 30 (SQ2). When the software file has a large capacity, the transfer of the ONT software file is divided into a plurality of messages and transferred to the OLT 10.

  When the transfer of the ONT software file to the OLT 10 is completed, the monitoring control device 30 instructs the OLT 10 to transfer the ONT software file by a control message designating the file name and the port ID (SQ3). Here, the multicast port IDs of the ONTs 20-1 to 20-n are designated as the port IDs. However, the monitoring control device 30 may specify the identifier of the optical fiber 40 instead of specifying the multicast port ID. In this case, conversion to the multicast port ID is performed on the OLT 10 side.

  Upon receiving the ONT software file transfer instruction, the OLT 10 reads the ONT software file from the memory 15, divides the ONT software file into a plurality of data blocks as described with reference to FIG. 50 is generated (S2). Next, the OLT 10 generates a GTC TC downstream frame 70 including the GEM client frame 50 in the payload (S3), and transmits it to the optical fiber 40 (SQ4).

  The GTC TC downstream frame 70 is branched from the optical fiber 40 to branch optical fibers 41-1 to 41-n and reaches a plurality of ONTs 20-1 to 20-n. Each ONT 20 confirms the port ID indicated by the header 51 of the GEM client frame included in the payload of the received GTC TC downstream frame (S11). When detecting that the port ID is for multicast, each ONT 20 stores the software data block included in the GEM payload in the software memory 25 (S12), and a response indicating that the OLT 10 has received the GEM client frame. The message is returned (SQ5).

  When the OLT 10 receives response messages from all ONTs connected to the optical fiber 40, the OLT 10 checks whether there is a data block to be transmitted (S4), and if there is an untransmitted data block, generates a GEM client frame 50. (S2), this is loaded on the GTC TC downstream 70 (S3) and transmitted to the optical fiber 40 (SQ4). When the transfer of all data blocks of the ONT software is completed, the OLT 10 transmits a file transfer completion notification message to the monitoring control device 30 (SQ6).

  According to the present embodiment, software files can be stored in a plurality of ONTs by effectively using the payloads of the GTC TC downstream frame and the GEM frame, and without including a GEM frame that overlaps the contents of the GTC TC downstream frame. Therefore, ONT software maintenance can be completed efficiently in a short time.

  When the software is divided into 38837-byte data blocks to maximize the utilization rate of the GTC payload, the payload of the GTC TC downstream frame is occupied by the GEM client frame for software transfer. The frame cannot be transferred. Therefore, if the GTC TC downstream is continuously used for software transfer to the ONT, the first signal processing unit 11 of the OLT cannot transfer the data packet received from the network NW1, and the reception buffer overflows. there is a possibility.

  In order to avoid the overflow of the reception buffer, the signal processing unit 11 determines whether or not the GEM client frame for software transfer can be transmitted from the data accumulation state of the reception buffer, and the GEM from the control unit 13 to the signal processing unit 11 The sending of client frames may be controlled.

  As an alternative method, when a software transfer request is received from the control unit 13, the payload length of the GEM client frame for software transfer is specified from the signal processing unit 11 to the control unit 13, and the control unit 13 is specified. The software data block may be transmitted with a payload length. In this case, since the payload of the GTC TC downstream frame can be shared by the GEM client frame for software transfer and the GEM client frame for normal user data, the accumulated data in the reception buffer can be continuously discharged.

  The payload length of the GEM client frame for software transfer is dynamically specified for each GTC TC downstream frame from the signal processing unit 11 to the control unit 13 according to the data accumulation state of the reception buffer in the signal processing unit 11. It may be. In this case, when the designated payload length is zero, transmission of the GEM client frame for software transfer is suppressed, and when the maximum length (38837 bytes), the GTC TC downstream frame is occupied for software transfer, and the maximum length If not, the GTC TC downstream frame is shared by the GEM client frame for software transfer and the GEM client frame for normal user data.

1 is a configuration diagram showing an example of a G-PON system to which the present invention is applied. The format figure of a GEM client frame. The format figure of an OMCI frame. The format figure of a GTC TC downstream frame. The figure for demonstrating the relationship between the data block and communication frame in the conventional software file transfer. The figure for demonstrating the relationship between the data block and communication frame in the software file transfer of this invention. The sequence diagram of the software file transfer by this invention.

Explanation of symbols

10: Station side device OLT, 20 subscriber connection device ONT, 30: supervisory control device, 40: optical fiber, 41: branch optical fiber, 42: optical coupler, 11, 14, 21, 31: signal processing unit, 13, 23, 33: Control unit, 15, 25, 35: ONT software file memory, 50: GEM client frame, 60: OMCI frame, 70: GTC TC downstream frame.

Claims (5)

Are connected by the optical line terminal (OLT) and a plurality of subscriber connection devices (ONT) and the passive optical network (PON), addressed to any ONT from the OLT, the user data is loaded into the variable length of the client frames, monitoring The control data is transmitted by mounting the destination ONT in a fixed-length monitoring control frame that cannot be specified by the multicast port ID, and mounting the client frame and the control monitoring frame in the payload portion of the downstream frame unique to the PON section. A software transfer method in the PON system as described above ,

Above the OLT, the software to be distributed to the ONT is divided into a plurality of data blocks having a larger byte length than the payload of the monitoring control frame, if the software where the software is distributed to the plurality of ONT, each The data block is mounted on the payload portion of the client frame including the multicast port ID in the header portion, and the client frame is mounted on the payload portion of the downstream frame unique to the PON section and transmitted to the optical fiber of the passive optical network. And
Each ONT which has received the downstream frame, transferred from the client frame including a port ID for multicast header and extracts the data blocks, the software characterized by storing the data block in the memory for the software file Method. The client frame is a GEM (G-PON Encapsulation Mode) client frame;
The monitoring control frame is an OMCI (ONT Management Control Interface) frame;
The software transfer method according to claim 1, wherein the downstream frame transmitted from the OLT to the PON section is a GTC (G-PON Transmission Convergence) TC downstream frame. 3. The software transfer method according to claim 2, wherein each GTC TC downstream frame includes a single GEM client frame for software transfer. 4. The software transfer method according to claim 3, wherein the OLT divides the software file into data blocks having a maximum length of 38837 bytes. Depending on the accumulation status of data packets to be transferred to the passive optical network, the OLT has a payload length of a client frame in which the software data block is mounted, or the client frame in which the software data block is mounted. 5. The software transfer method according to claim 1, wherein mounting on a downstream frame is controlled.

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