WO2022267543A1 - 一种数据帧的分片方法、数据帧的解析方法及相关设备 - Google Patents

一种数据帧的分片方法、数据帧的解析方法及相关设备 Download PDF

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Publication number
WO2022267543A1
WO2022267543A1 PCT/CN2022/079466 CN2022079466W WO2022267543A1 WO 2022267543 A1 WO2022267543 A1 WO 2022267543A1 CN 2022079466 W CN2022079466 W CN 2022079466W WO 2022267543 A1 WO2022267543 A1 WO 2022267543A1
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Prior art keywords
message
header
onu
target
olt
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PCT/CN2022/079466
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English (en)
French (fr)
Inventor
颜林志
张伦
聂世玮
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华为技术有限公司
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Priority to EP22827048.4A priority Critical patent/EP4322546A1/en
Publication of WO2022267543A1 publication Critical patent/WO2022267543A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0041—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/0064—Arbitration, scheduling or medium access control aspects

Definitions

  • the present application relates to the field of optical communication, in particular to a data frame fragmentation method, a data frame analysis method and related equipment.
  • the current PON system includes gigabit PON (gigabit-capable PON, GPON), 10 gigabit per second PON (10gigabit per second PON, XG-PON), symmetrical 10 gigabit passive optical network (10-gigabit-capable symmetric passive optical network, XGS-PON), 25 gigabit per second PON (25gigabit per second PON, 25G-PON), 50 gigabit per second PON (50gigabit per second PON, 50G-PON), etc.
  • gigabit PON gigabit-capable PON, GPON
  • 10 gigabit per second PON (10gigabit per second PON, XG-PON)
  • symmetrical 10 gigabit passive optical network (10-gigabit-capable symmetric passive optical network, XGS-PON)
  • 25 gigabit per second PON 25gigabit per second PON, 25G-PON
  • 50 gigabit per second PON 50gigabit per second PON, 50G
  • each frame header needs to be sent as a whole before the service message can be sent.
  • the length of the frame header 4+8*B+48*P, where B is the number of bandwidth maps (BWmap), P is the physical layer operation management and maintenance (Physical Layer Operations , Administration and Maintenance, PLOAM) number of messages. Therefore, the length of the frame header may range from tens of bytes to several kilobytes. If there are many BWmap and PLOAM messages to be sent, it will bring a large delay to the sending of service messages.
  • the present application provides a data frame fragmentation method, a data frame analysis method and related equipment. If the length of the frame header exceeds the specified length, the OLT will actively fragment the frame header, and the fragmented sub-frame headers can support packet preemption, reducing the packet transmission delay.
  • the present application provides a data frame fragmentation method.
  • the method includes: the OLT generates an original data frame, and the original data frame includes a frame header and a message. If the length of the frame header is greater than the first preset value, the OLT fragments the frame header to obtain the target data frame. The length of each subframe header after the frame header is fragmented is less than or equal to the first preset value.
  • the target data frame includes a plurality of codewords, at least one codeword includes a first field, each codeword includes a second field, and at least one codeword further includes a third field.
  • the first field is used to carry the subframe header and the first message with low priority
  • the second field is used to carry the check code
  • the third field is used to carry the second message with high priority.
  • the sending order of the first message is located after the subframe header with the highest sending order, and the sending order of the first message is located before the sending order of at least one subframe header. Further, the OLT sends the target data frame to the optical network unit ONU.
  • the OLT will actively fragment the frame header.
  • the length of each subframe header after fragmentation does not exceed the specified length.
  • message preemption may be supported between the subframe headers of the fragments. That is to say, there is no need to wait for the entire frame header to be sent before sending the message, and the message can be sent between any sub-frame headers, which reduces the transmission delay of the message.
  • some or all of the codewords can also reserve fields for high-priority packets, thereby reducing the number of high-priority packets. transmission delay.
  • the frame header is a downstream physical control block (Physical Control Block downstream, PCBd).
  • PCBd Physical Control Block downstream
  • the OLT needs to use GPON encapsulation mode (GPON Encapsulation Mode, GEM) for the other subframe headers except the first subframe header, and the fragmentation is located at the starting position
  • GEM GPON Encapsulation Mode
  • the first subframe header still adopts the format of PCBd before fragmentation.
  • the frame header may also be a superframe (Superframe, FS) frame header.
  • the OLT needs to use the XG-PON encapsulation mode (XG-PON Encapsulation Mode, XGEM) for other subframe headers except the first subframe header.
  • XG-PON Encapsulation Mode XGEM
  • the first subframe header at the starting position still adopts the format of the FS frame header before fragmentation.
  • each subframe header includes a target GEM port identifier or a target XGEM port identifier
  • the method further includes: the OLT sends a first notification message to the ONU.
  • the first notification message includes a target GEM port identifier or a target XGEM port identifier. It should be understood that the message also needs to be encapsulated with GEM or XGEM. In order to enable the ONU to distinguish the message from the subframe header, it is necessary to define a dedicated target GEM port identifier or target XGEM port identifier for the subframe header to distinguish it from the subframe header.
  • the OLT sends the target GEM port identifier or the target XGEM port identifier to each ONU in advance, so that the ONU can smoothly analyze each subframe header after receiving the target data frame.
  • the ONU includes a first ONU and a second ONU, the first ONU supports fragmentation of the frame header, and the second ONU does not support fragmentation of the frame header.
  • each subframe header in the target data frame sent by the OLT to the first ONU includes a bandwidth map (bandwidth map, BWmap) and a downstream physical layer operation management and maintenance (Physical Layer Operations, Administration and Maintenance downstream, PLOAMd) message.
  • the target subframe header sent by the OLT to the second ONU includes BWmap and PLOAM messages, and the target subframe header is the subframe header with the highest sending order in the target data frame.
  • the above-mentioned processing method is applicable to the scene where old and new ONUs exist at the same time, and can be compatible with new ONUs that support frame header fragmentation and old ONUs that do not support fragmentation, which improves the practicability of this solution.
  • the method before the OLT sends the target data frame to the ONU, the method further includes: if the sending order of the first message is before the sending order of the second message and the length of the first message is greater than the second preset value, the OLT fragments the first packet. The length of each sub-message after the fragmentation of the first message is less than or equal to the second preset value, the sending order of the second message is after the sub-message with the highest sending order, and the sending order of the second message Prior to the sending order of at least one sub-message.
  • the second high-priority message is supported to preempt the position, which can effectively reduce the transmission delay of the high-priority message.
  • each sub-message is encapsulated by GEM or XGEM, so as to be compatible with existing standards, and facilitate the ONU to analyze each sub-message.
  • the third field includes multiple subfields, and each subfield is used to carry a part of the second packet.
  • different subfields can carry services belonging to different ONUs, which further improves the practicability of this solution.
  • the method before the OLT sends the target data frame to the ONU, the method further includes: the OLT sends a second notification message to the ONU, where the second notification message is used to indicate the target subfield corresponding to the ONU and the target subfield The starting position and length of .
  • the entire third field is encapsulated in GEM or XGEM, but in order to save overhead, each subfield is not encapsulated in GEM or XGEM one by one. Therefore, the OLT needs to send the configuration information of each subfield to each ONU, so that each ONU can extract data from its corresponding subfield.
  • the present application provides a data frame parsing method.
  • the method includes: the ONU receives the target data frame sent by the OLT.
  • the target data frame is obtained by fragmenting the frame header of the original data frame by the OLT.
  • the length of each subframe header after the frame header is fragmented is less than or equal to the first preset value.
  • the target data frame includes a plurality of codewords, at least one codeword includes a first field, each codeword includes a second field, and at least one codeword further includes a third field.
  • the first field is used to carry the subframe header and the first message
  • the second field is used to carry the check code
  • the third field is used to carry the second message.
  • the priority of the first packet is lower than that of the second packet, the sending order of the first packet is after the subframe header with the highest sending order, and the sending order of the first packet is at least one subframe header before the sending sequence. Furthermore, the ONU sequentially analyzes the codewords in the target data frame.
  • the frame header is PCBd.
  • the OLT needs to use GEM to encapsulate the other subframe headers except the first subframe header, and the fragmentation
  • the first subframe header at the starting position still adopts the format of PCBd before fragmentation.
  • the frame header can also be an FS frame header.
  • the OLT needs to use XGEM to encapsulate the other subframe headers except the first subframe header.
  • the first subframe header at the starting position still adopts the format of the FS frame header before fragmentation.
  • each subframe header includes a target GEM port identifier or a target XGEM port identifier
  • the method further includes: the ONU receives a first notification message sent by the OLT.
  • the first notification message includes a target GEM port identifier, and the target GEM port identifier is used to indicate the subframe header that adopts GEM encapsulation.
  • the first notification message includes a target XGEM port identifier, where the target XGEM port identifier is used to indicate that a subframe header using XGEM encapsulation is used.
  • each subframe header includes BWmap and PLOAM messages. If the ONU does not support fragmentation of the frame header, the target subframe header includes BWmap and PLOAM messages, and the target subframe header is the subframe header with the highest sending order in the target data frame.
  • the sending order of the first message is before the sending order of the second message and the length of the first message is greater than the second preset value
  • the first message is fragmented by the OLT into multiple sub-messages, the length of each sub-message is less than or equal to the second preset value
  • the sending order of the second message is located after the sub-message with the highest sending order
  • the sending order of the second message is located at least one sub-message before the sending sequence of the message.
  • each sub-message is encapsulated by GEM or XGEM.
  • the third field includes multiple subfields, and each subfield is used to carry a part of the second packet.
  • the method before the ONU receives the target data frame sent by the OLT, the method further includes: the ONU receives a second notification message sent by the OLT.
  • the second notification message is used to indicate the target subfield corresponding to the ONU and the start position and length of the target subfield.
  • the present application provides an OLT.
  • the OLT includes a processor and a transceiver, the processor and the transceiver are connected to each other through a line, and the processor is used to execute part or all of the steps of any method in the first aspect.
  • the OLT further includes a memory
  • the processor invokes the program code in the memory to execute part or all of the steps of any method in the first aspect.
  • the present application provides an ONU.
  • the ONU includes a processor and a transceiver, the processor and the transceiver are connected to each other through a line, and the processor is used to execute part or all of the steps of any method in the second aspect.
  • the ONU further includes a memory, and the processor invokes the program code in the memory to execute part or all of the steps of any method in the second aspect.
  • the present application provides an OLT.
  • the OLT includes a processing unit and a transceiver unit.
  • the processing unit is used for: generating an original data frame, and the original data frame includes a frame header and a message. If the length of the frame header is greater than the first preset value, the OLT fragments the frame header to obtain the target data frame. The length of each subframe header after the frame header is fragmented is less than or equal to the first preset value.
  • the target data frame includes a plurality of codewords, at least one codeword includes a first field, each codeword includes a second field, and at least one codeword further includes a third field.
  • the first field is used to carry the subframe header and the first message with low priority
  • the second field is used to carry the check code
  • the third field is used to carry the second message with high priority.
  • the sending order of the first message is located after the subframe header with the highest sending order, and the sending order of the first message is located before the sending order of at least one subframe header.
  • the transceiver unit is used for the OLT to send the target data frame to the optical network unit ONU.
  • the frame header is PCBd.
  • the OLT needs to use GEM to encapsulate the other subframe headers except the first subframe header, and the fragmentation
  • the first subframe header at the starting position still adopts the format of PCBd before fragmentation.
  • the frame header can also be an FS frame header.
  • the OLT needs to use XGEM to encapsulate the other subframe headers except the first subframe header.
  • the first subframe header at the starting position still adopts the format of the FS frame header before fragmentation.
  • each subframe header includes a target GEM port identifier or a target XGEM port identifier.
  • the transceiver unit is further configured to: send a first notification message to the ONU.
  • the first notification message includes a target GEM port identifier, and the target GEM port identifier is used to indicate the subframe header that adopts GEM encapsulation.
  • the first notification message includes a target XGEM port identifier, where the target XGEM port identifier is used to indicate that a subframe header using XGEM encapsulation is used.
  • the ONU includes a first ONU and a second ONU, the first ONU supports fragmentation of the frame header, and the second ONU does not support fragmentation of the frame header.
  • each subframe header in the target data frame sent by the OLT to the first ONU includes BWmap and PLOAM messages.
  • the target subframe header sent by the OLT to the second ONU includes BWmap and PLOAM messages, and the target subframe header is the subframe header with the highest sending order in the target data frame.
  • the processing unit before the transceiver unit sends the target data frame to the ONU, the processing unit is further configured to: if the sending order of the first message is before the sending order of the second message and the length of the first message is greater than the length of the first message Two preset values, the first packet is fragmented. The length of each sub-message after the fragmentation of the first message is less than or equal to the second preset value, the sending order of the second message is after the sub-message with the highest sending order, and the sending order of the second message Prior to the sending order of at least one sub-message.
  • each sub-message is encapsulated by GEM or XGEM.
  • the third field includes multiple subfields, and each subfield is used to carry a part of the second packet.
  • the transceiver unit before the transceiver unit sends the target data frame to the ONU, the transceiver unit is further configured to: send a second notification message to the ONU.
  • the second notification message is used to indicate the target subfield corresponding to the ONU and the start position and length of the target subfield.
  • the present application provides an ONU.
  • the ONU includes a processing unit and a transceiver unit.
  • the transceiver unit is used for: receiving the target data frame sent by the optical line terminal OLT.
  • the target data frame is obtained by fragmenting the frame header of the original data frame by the OLT, and the length of each subframe header after the fragmentation of the frame header is less than or equal to the first preset value.
  • the target data frame includes a plurality of codewords, at least one codeword includes a first field, each codeword includes a second field, and at least one codeword further includes a third field.
  • the first field is used to carry the subframe header and the first message
  • the second field is used to carry the check code
  • the third field is used to carry the second message.
  • the priority of the first packet is lower than that of the second packet
  • the sending order of the first packet is after the subframe header with the highest sending order
  • the sending order of the first packet is at least one subframe header before the sending sequence.
  • the processing unit is configured to sequentially analyze the codewords in the target data frame.
  • the frame header is PCBd.
  • the OLT needs to use GEM to encapsulate the other subframe headers except the first subframe header, and the fragmentation
  • the first subframe header at the starting position still adopts the format of PCBd before fragmentation.
  • the frame header can also be an FS frame header.
  • the OLT needs to use XGEM to encapsulate the other subframe headers except the first subframe header.
  • the first subframe header at the starting position still adopts the format of the FS frame header before fragmentation.
  • each subframe header includes a target GEM port identifier or a target XGEM port identifier
  • the transceiver unit is further configured to: receive a first notification message sent by the OLT.
  • the first notification message includes a target GEM port identifier, and the target GEM port identifier is used to indicate the subframe header that adopts GEM encapsulation.
  • the first notification message includes a target XGEM port identifier, where the target XGEM port identifier is used to indicate that a subframe header using XGEM encapsulation is used.
  • each subframe header includes BWmap and PLOAM messages. If the ONU does not support fragmentation of the frame header, the target subframe header includes BWmap and PLOAM messages, and the target subframe header is the subframe header with the highest sending order in the target data frame.
  • the sending order of the first message is before the sending order of the second message and the length of the first message is greater than the second preset value
  • the first message is fragmented by the OLT into multiple sub-message.
  • the length of each sub-message is less than or equal to the second preset value
  • the sending order of the second message is located after the sub-message with the highest sending order
  • the sending order of the second message is located after the sending order of at least one sub-message before the order.
  • each sub-message is encapsulated by GEM or XGEM.
  • the third field includes multiple subfields, and each subfield is used to carry a part of the second packet.
  • the transceiver unit before the transceiver unit receives the target data frame sent by the OLT, the transceiver unit is further configured to: receive a second notification message sent by the OLT.
  • the second notification message is used to indicate the target subfield corresponding to the ONU and the start position and length of the target subfield.
  • the OLT will actively fragment the frame header.
  • the length of each subframe header after fragmentation does not exceed the specified length.
  • message preemption may be supported between the subframe headers of the fragments. That is to say, there is no need to wait for the entire frame header to be sent before sending the message, and the message can be sent between any sub-frame headers, which reduces the transmission delay of the message.
  • some or all of the codewords can also reserve fields for high-priority packets, thereby reducing the number of high-priority packets. transmission delay.
  • FIG. 1 is a schematic diagram of a system architecture of a PON
  • Fig. 2 is the schematic diagram of an embodiment of the fragmentation method of data frame in the present application.
  • Fig. 3 (a) is a kind of structural representation of GTC frame in GPON standard
  • Figure 3(b) is a schematic structural diagram of an FS frame in the XG-PON standard
  • Fig. 4 (a) is a schematic diagram of the structure after PCBd fragmentation in the GTC frame
  • Fig. 4 (b) is a kind of structure schematic diagram after FS header fragmentation in FS frame
  • Fig. 5 is a schematic diagram of an embodiment of capability negotiation between OLT and ONU in the embodiment of the present application
  • FIG. 6 is a schematic structural diagram of an FEC codeword in an existing standard
  • Fig. 7 (a) is the first structure schematic diagram of the FEC code word in the embodiment of the present application.
  • Fig. 7 (b) is the second structure diagram of FEC code word in the embodiment of the present application.
  • Fig. 7 (c) is the second structure diagram of FEC code word in the embodiment of the present application.
  • FIG. 8 is a schematic diagram of an embodiment of the OLT notifying the ONU of the subfield configuration information in the embodiment of the present application
  • FIG. 9 is a schematic diagram of an embodiment of a method for parsing a data frame in the present application.
  • FIG. 10 is a schematic structural diagram of a possible OLT in the embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of another possible OLT in the embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a possible ONU in the embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of another possible ONU in the embodiment of the present application.
  • the present application provides a data frame fragmentation method, a data frame analysis method and related equipment. If the length of the frame header exceeds the specified length, the OLT will actively fragment the frame header, and the fragmented sub-frame headers can support packet preemption, reducing the packet transmission delay.
  • This application is mainly applied in a passive optical network (passive optical network, PON) system, and the system architecture of the PON is introduced below.
  • PON passive optical network
  • FIG. 1 is a schematic diagram of a system architecture of a PON.
  • the OLT is connected to upper-layer network-side devices (such as switches, routers, etc.), and the lower layer is connected to one or more optical distribution networks (ODN).
  • ODN optical distribution networks
  • the ODN includes a passive optical splitter for optical power distribution, a trunk fiber connected between the passive optical splitter and the OLT, and a branch fiber connected between the passive optical splitter and the ONU.
  • the ODN transmits the downstream data of the OLT to each ONU through an optical splitter, and the ONU selectively receives the downstream data carrying its own identification.
  • the ODN When transmitting data upstream, the ODN combines the optical signals sent by N ONUs into one optical signal and transmits it to the OLT. If the ONU provides user port functions at the same time, such as the ONU provides Ethernet user ports or traditional telephone service (plain old telephone service, POTS) user ports, it is called an optical network termination (ONT).
  • ONT optical network termination
  • each frame header needs to be sent as a whole before sending the message. If the frame header is too long, it will bring a large delay to the transmission of the message. For this reason, this application provides a method for fragmenting a data frame, which will be described in detail below.
  • FIG. 2 is a schematic diagram of an embodiment of a data frame fragmentation method in the present application.
  • the data frame fragmentation method includes the following steps.
  • the OLT generates an original data frame.
  • the original data frame includes a frame header and a message, wherein the frame header is located at the beginning of the original data frame.
  • the frame header is a downstream physical control block (Physical Control Block downstream, PCBd).
  • Fig. 3(a) is a schematic diagram of a structure of a GTC frame in the GPON standard.
  • PCBd includes physical synchronization sequence (Physical synchronization sequence, Psync), identification (Ident), downlink physical layer operation management and maintenance (Physical Layer Operations, Administration and Maintenance downstream, PLOAMd), bit cross parity Checksum (Bit Interleaved Parity, BIP), downlink payload length (Payload Length downstream, Plend) and bandwidth mapping table (bandwidth map, BWmap).
  • the superframe payload (FS payload) is used to carry the message.
  • the frame header is a superframe (Superframe, FS) frame header.
  • FIG. 3(b) is a schematic structural diagram of an FS frame in the XG-PON standard.
  • the FS frame header includes the downlink frame header length (Header Length downstream, Hlend), BWmap and PLOAMd.
  • the GTC frame payload is used to carry packets.
  • the original data frame includes multiple packets with different priorities.
  • the original data frame includes a first message and a second message, wherein the first message is a common message, and the second message is a message that is more sensitive to delay, that is, the priority of the first message is low on the priority of the second packet.
  • the OLT fragments the frame header to obtain the target data frame.
  • the OLT may actively segment the frame header into multiple sub-frame headers.
  • the length of each subframe header after fragmentation must be less than or equal to the first preset value.
  • the message preempts the position among the sub-frame headers, that is, the sending order of the message can be before the sending order of at least one sub-frame header. It should be understood that the first subframe header after the fragmentation of the frame header is still located at the beginning of the data frame, so the sending order of the message must be after the sending order of the first subframe header.
  • this application does not limit the specific length of each subframe header, and can be divided into pieces according to equal divisions, so that the length of each subframe header is the same as possible, or the length of each subframe header can also be adjusted randomly .
  • the above-mentioned first preset value can be flexibly configured. Taking the FS frame header with 128 BWmaps and 64 PLOAMd as an example, the total length of the FS frame header is 4100 bytes. If the first preset value is set to 512 bytes, you can Fragment the FS frame header into 9 subframe headers. If the length of the first subframe header is 512 bytes, then the message can be sent only after the 512-byte subframe header is sent.
  • Fig. 4(a) is a schematic diagram of a structure after PCBd fragmentation in a GTC frame.
  • subframe header 1 adopts the frame header format before PCBd fragmentation
  • subframe header 2 is encapsulated by GEM, and the position of the message is located between subframe header 1 and subframe header 2.
  • the number of BWmaps is indicated by Plend in each subframe header. Since Plend does not support error correction, it is necessary to repeatedly send Plend twice in each subframe header, and the ONU can select the correct one for Cyclic Redundancy Check (CRC). Use Plend.
  • Figure 4(b) is a schematic diagram of the structure of the fragmented FS frame header in the FS frame.
  • subframe header 1 adopts the frame header format before FS header fragmentation
  • subframe header 2 uses XGEM for encapsulation
  • the position of the message is located between subframe header 1 and subframe header 2.
  • Hlend in each subframe header is used to indicate the number of PLOAMd and the number of BWmap. It can be seen from the comparison that after PCBd is fragmented, only PLOAMd and BWmap are sent in the first subframe header, and only BWmap needs to be sent in other subframe headers.
  • each sub-frame header after fragmentation of the FS frame header supports sending PLOAMd and BWmap, and the fragmented sub-frame header can only send PLOAMd, or only BWmap, or send PLOAMd and BWmap at the same time.
  • each subframe header encapsulated by GEM has a GEM port identifier (GEM Port ID), wherein the GEM port identifier is located in the GEM frame header as shown in Figure 4(a).
  • each subframe header encapsulated by XGEM has an XGEM port identifier (XGEM Port ID), wherein the XGEM port identifier is located in the XGEM frame header as shown in Figure 4(b).
  • XGEM Port ID XGEM port identifier
  • the message also needs to be encapsulated with GEM or XGEM. In order to enable the ONU to distinguish the message from the subframe header, it is necessary to define a dedicated GEM Port ID or XGEM Port ID for the subframe header to distinguish it from the subframe header.
  • not all ONUs support frame header fragmentation. There will be certain differences in the processing methods between ONUs that support frame header fragmentation and ONUs that do not support frame header fragmentation. Negotiations between the capabilities are described below.
  • FIG. 5 is a schematic diagram of an embodiment of capability negotiation between the OLT and the ONU in the embodiment of the present application.
  • the OLT sends a registration and online message to the ONU.
  • the OLT Since the OLT has not yet determined whether the ONU supports frame header fragmentation, the OLT will send the PLOAMd and BWmap related to registration and online to the ONU through the first subframe header after the frame header fragmentation. In this way, even if the ONU does not support frame header fragmentation, the registration and online message sent by the OLT can be parsed through the first sub-frame header.
  • the ONU sends an uplink optical signal to the OLT.
  • the OLT can obtain the serial number (Serial Number, SN) of the ONU through the upstream optical signal sent by the ONU, and the OLT can assign the corresponding identity (Identity document, ID) to the ONU. Furthermore, the OLT will also perform ranging on the ONU, and allocate a corresponding uplink transmission time slot for the ONU, and the registration of the ONU has been completed.
  • Serial Number, SN Serial Number
  • ID Identity document
  • the OLT sends a capability negotiation message to the ONU.
  • the OLT sends a capability negotiation message to the ONU to instruct the ONU to report whether it supports the OLT to fragment the frame header.
  • the ONU sends a capability negotiation response to the OLT.
  • the ONU After receiving the capability negotiation message sent by the OLT, the ONU will report to the OLT whether it has the capability to support frame header fragmentation.
  • the OLT judges whether the ONU supports frame header fragmentation, if not, execute step 506, and if yes, execute step 507.
  • the OLT sends the PLOAMd and the BWmap to the ONU through the first subframe header.
  • the ONU does not support frame header fragmentation, it means that the ONU cannot parse the subframe header encapsulated in GEM or XGEM. Then, OLT will send PLOAMd and BWmap to ONU through the first subframe header.
  • the OLT sends a dedicated GEM Port ID or XGEM Port ID to the ONU.
  • the ONU If the ONU supports frame header fragmentation, it means that the ONU can parse subframe headers encapsulated in GEM or XGEM. Then, the ONU needs to send the dedicated GEM Port ID or XGEM Port ID to the ONU in advance, so that the ONU can successfully parse each subframe header. Specifically, the OLT can send a dedicated GEM Port ID or XGEM Port ID to the ONU through a PLOAM message or an Optical Network Unit Management Control Interface (ONU Management and Control Interface, OMCI) message.
  • ONU Management and Control Interface Optical Network Unit Management Control Interface
  • the ONU sends a response message to the OLT.
  • the ONU informs itself that it has received the dedicated GEM Port ID or XGEM Port ID by sending a response message to the OLT. It should be noted that before the OLT receives the response message sent by the ONU, it still only sends PLOAMd and BWmap to the ONU through the first subframe header. After the OLT receives the response sent by the ONU, the OLT can send PLOAMd and BWmap to the ONU through multiple subframe headers after the frame header fragmentation.
  • the above-mentioned processing method is applicable to a scene where old and new ONUs exist at the same time, and can be compatible with new ONUs that support frame header fragmentation and old ONUs that do not support fragmentation.
  • the OLT can also directly send the dedicated GEM Port ID or XGEM Port ID to the ONU without negotiating capabilities with the ONU.
  • the OLT may also actively fragment the first packet. After the first message is fragmented, a plurality of sub-messages are obtained, and the second message can preempt positions among the sub-messages, that is, the sending order of the second message can be before the sending order of at least one sub-message.
  • the transmission delay of the high-priority message can be effectively reduced. It should be understood that, in order to be compatible with existing standards and enable the ONU to parse the fragmented sub-messages, each sub-message also needs to be encapsulated with GEM or XGEM.
  • Fig. 6 is a schematic diagram of the structure of an FEC codeword in an existing standard. As shown in FIG. 6 , N codewords can be formed after performing FEC encoding on a superframe, and each codeword includes field 1 and field 2 . Wherein, field 1 is used to carry a superframe header and/or message, and field 2 is used to carry a check code.
  • FEC Forward Error Correction
  • N codewords and a downstream physical synchronization block constitute a PHY frame, and the payload area of the PHY frame is used to carry the N codewords.
  • PSBd downstream physical synchronization block
  • the multiple fields in each codeword above can also be understood as being divided into multiple time slots, and different time slots are used to transmit different information.
  • not every codeword can transmit high-priority messages. In order to reduce the transmission delay of high-priority messages, this application considers reserving The field of the high-priority message, so that the deterministic transmission delay can be provided for the high-priority message, which will be further introduced below.
  • Fig. 7(a) is a schematic diagram of the first structure of the FEC codeword in the embodiment of the present application.
  • the target data frame after FEC encoding includes N codewords.
  • Each codeword includes field 1, field 2 and field 3.
  • field 1 is used to carry the fragmented subframe header and/or the first packet with low priority
  • field 2 is used to carry the check code
  • field 3 is used to carry the second packet with high priority.
  • the lengths of field 1 and field 3 in each codeword may be fixed or variable, and the details are not limited here.
  • the relative positions of field 1 and field 3 in each codeword may be fixed or changeable, which is not specifically limited here. For example, the position of field 1 in the previous codeword may be before field 3, and the position of field 3 in the next codeword may be before field 1.
  • Fig. 7(b) is a schematic diagram of the second structure of the FEC codeword in the embodiment of the present application.
  • field 3 does not need to be reserved in every codeword, and field 3 can be configured with M codewords as a cycle according to actual needs. For example, if field 3 is configured in codeword 1, then the next codeword configured with field 3 is codeword M+1.
  • the present application does not limit the value of M. Wherein, the smaller the value of M, the better the transmission delay of the high-priority message service can be reduced, but it will also occupy more resources. Therefore, the value of M can be flexibly set according to actual requirements.
  • each codeword needs to include a field 2 for carrying a check code.
  • Codeword 1 must include field 1 for carrying a frame header, and optionally, codeword 1 may also include field 3.
  • Codewords other than codeword 1 may only include field 1 and field 2, or may only include field 2 and field 3, or may also include field 1, field 2, and field 3 at the same time.
  • Fig. 7(c) is a schematic diagram of the second structure of the FEC codeword in the embodiment of the present application.
  • the embodiment of the present application can further divide multiple subfields on the basis of the above-mentioned field 3, and each subfield is used to carry part of the second message, and the present application does not limit the field 3 The number of divided subfields and the length of each subfield. It should be understood that the entire field 3 is encapsulated in GEM or XGEM, but in order to save overhead, each subfield is not encapsulated in GEM or XGEM one by one. Therefore, in order to facilitate each ONU to extract data from its corresponding subfield, the OLT needs to send the configuration information of each subfield to each ONU, which will be described below.
  • FIG. 8 is a schematic diagram of an embodiment in which the OLT notifies the ONU of subfield configuration information in the embodiment of the present application.
  • the OLT sends subfield configuration information to the ONU.
  • the OLT may send the subfield configuration information to the ONU through a PLOAM message or an OMCI message.
  • the configuration information includes the start position and length of the target subfield corresponding to the ONU. It should be understood that different subfields can carry services belonging to different ONUs. Therefore, the OLT needs to notify each ONU of the start position and length of the corresponding subfields, so that each ONU can extract services from its corresponding subfields.
  • the ONU sends a response message to the OLT to confirm receipt of the subfield configuration information.
  • the OLT sends the target data frame to the ONU.
  • the OLT will send high priority services to the ONU through the subfield in the target data frame.
  • the OLT sends the updated subfield configuration information to the ONU.
  • the configuration information of each subfield in the above field 3 may change, then the OLT needs to send the updated configuration information of the subfields to the ONU.
  • the ONU sends a response message to the OLT to confirm receipt of the updated subfield configuration information.
  • the OLT sends the updated target data frame to the ONU.
  • the OLT sends the target data frame to the ONU.
  • the OLT will send the obtained target data frame to the ONU.
  • the OLT will actively fragment the frame header.
  • the length of each subframe header after fragmentation does not exceed the specified length.
  • message preemption may be supported between the subframe headers of the fragments. That is to say, there is no need to wait for the entire frame header to be sent before sending the message, and the message can be sent between any sub-frame headers, which reduces the transmission delay of the message.
  • some or all of the codewords can also reserve fields for high-priority packets, thereby reducing the number of high-priority packets. transmission delay.
  • the fragmentation method of the data frame executed by the OLT is introduced above, and the analysis method of the data frame executed by the ONU is introduced below.
  • FIG. 9 is a schematic diagram of an embodiment of a data frame parsing method in the present application.
  • the parsing method of the data frame includes the following steps.
  • the ONU receives the target data frame sent by the OLT.
  • step 202 for the introduction of the target data, reference may be made to the relevant description of step 202 in the above embodiment shown in FIG. 2 , which will not be repeated here.
  • the ONU sequentially parses the codewords in the target data frame.
  • the ONU since the subframe headers in the codeword are encapsulated by GEM or XGEM, and the ONU can receive the dedicated GEM Port ID or XGEM Port ID sent by the OLT in advance. Therefore, the ONU can successfully analyze each subframe header according to the dedicated GEM Port ID or XGEM Port ID.
  • the ONU may also receive the configuration information of the subfields sent by the OLT in advance. According to the configuration information, the ONU can know the start position and length of its corresponding subfield, so that it can smoothly analyze each subfield in field 3.
  • the ONU For the introduction of sending the subfield configuration information from the OLT to the ONU, reference may be made to the above embodiment shown in FIG. 8 , which will not be repeated here.
  • the OLT and ONU provided by this application are introduced below.
  • FIG. 10 is a schematic structural diagram of a possible OLT in the embodiment of the present application.
  • the OLT includes a processing unit 1001 and a transceiver unit 1002 .
  • the processing unit 1001 is configured to execute step 201 and step 202 in the above embodiment shown in FIG. 2 .
  • the transceiver unit 1002 is configured to execute step 203 in the above embodiment shown in FIG. 2 .
  • the transceiving unit 1002 is also configured to perform the steps of information interaction with the ONU in the above embodiments shown in FIG. 5 and FIG. 8 .
  • FIG. 11 is a schematic structural diagram of another possible OLT in the embodiment of the present application.
  • the OLT includes a processor 1101 and a transceiver 1102, and the processor 1101 and the transceiver 1102 are connected to each other through lines.
  • the transceiver 1102 is configured to execute the operation of transmitting and receiving information by the OLT in the above embodiments shown in FIG. 2 , FIG. 5 and FIG. 8 .
  • the processor 1101 is configured to perform other operations of the OLT in the above-mentioned embodiments shown in FIG. 2 , FIG. 5 and FIG. 8 except information sending and receiving.
  • the processor 1101 includes the aforementioned processing unit 1001
  • the transceiver 1102 includes the aforementioned transceiver unit 1002
  • the OLT may further include a memory 1103, wherein the memory 1103 is used to store program instructions and data.
  • FIG. 12 is a schematic structural diagram of a possible ONU in the embodiment of the present application.
  • the ONU includes a processing unit 1201 and a transceiver unit 1202 .
  • the processing unit 1201 is configured to execute step 902 in the above embodiment shown in FIG. 9 .
  • the transceiver unit 1202 is configured to execute step 901 in the above embodiment shown in FIG. 9 .
  • the transceiving unit 1202 is also configured to perform the steps of information interaction with the OLT in the above embodiments shown in FIG. 5 and FIG. 8 .
  • FIG. 13 is a schematic structural diagram of another possible ONU in the embodiment of the present application.
  • the ONU includes a processor 1301 and a transceiver 1302, and the processor 1301 and the transceiver 1302 are connected to each other through lines.
  • the transceiver 1302 is used to execute the operation of transmitting and receiving information by the ONU in the above embodiments shown in FIG. 9 , FIG. 5 and FIG. 8 .
  • the processor 1301 is configured to perform other operations of the ONU in the above-mentioned embodiments shown in FIG. 9 , FIG. 5 and FIG. 8 except information sending and receiving.
  • the processor 1301 includes the aforementioned processing unit 1201
  • the transceiver 1302 includes the aforementioned transceiver unit 1202
  • the ONU may further include a memory 1303, wherein the memory 1303 is used to store program instructions and data.
  • the processors shown in the above-mentioned Fig. 11 and Fig. 13 may adopt a general-purpose central processing unit (Central Processing Unit, CPU), a microprocessor, an application-specific integrated circuit ASIC, or at least one integrated circuit for Relevant programs are executed to realize the technical solutions provided by the embodiments of the present application.
  • the memories shown in FIGS. 11 and 13 above can store operating systems and other application programs.
  • the program codes for realizing the technical solutions provided by the embodiments of the present application are stored in the memory and executed by the processor.
  • the processor may include a memory inside.
  • the processor and memory are two separate structures.
  • the above-mentioned processing unit or processor can be a central processing unit, a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices , transistor logic devices, hardware components, or any combination thereof.
  • DSP digital signal processor
  • ASIC application-specific integrated circuit
  • FPGA field programmable gate array
  • the computer program product includes one or more computer instructions.
  • the computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website, computer, server or data center Transmission to another website site, computer, server, or data center by wired (eg, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (eg, infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center integrated with one or more available media.
  • the available medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, DVD), or a semiconductor medium (for example, a Solid State Disk (SSD)).
  • SSD Solid State Disk

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Abstract

本申请提供了一种数据帧的分片方法、数据帧的解析方法及相关设备。OLT生成原始数据帧，该原始数据帧包括帧头和报文。若帧头的长度大于第一预设值，则OLT对帧头进行分片以得到目标数据帧。帧头分片后的每个子帧头的长度小于或等于第一预设值。目标数据帧包括多个码字，至少一个码字包括第一字段，每个码字包括第二字段，至少一个码字还包括第三字段。其中，第一字段用于承载子帧头和低优先级的第一报文，第二字段用于承载校验码，第三字段用于承载高优先级的第二报文。第一报文的发送次序位于发送次序最靠前的子帧头之后，且第一报文的发送次序位于至少一个子帧头的发送次序之前。进而，OLT向光网络单元ONU发送目标数据帧。

Description

一种数据帧的分片方法、数据帧的解析方法及相关设备
本申请要求于2021年6月22日提交中国国家知识产权局、申请号202110694345.1、申请名称为“一种数据帧的分片方法、数据帧的解析方法及相关设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光通信领域，尤其涉及一种数据帧的分片方法、数据帧的解析方法及相关设备。
背景技术
目前，越来越多的场景会用到无源光网络(Passive Optical Network，PON)***，这些场景均有低时延和低抖动的要求。目前的PON***包括千兆比特PON(gigabit-capable PON，GPON)、10吉比特每秒PON(10gigabit per second PON，XG-PON)、对称10吉比特无源光网络(10-gigabit-capable symmetric passive optical network，XGS-PON)、25吉比特每秒PON(25gigabit per second PON，25G-PON)、50吉比特每秒PON(50gigabit per second PON，50G-PON)等。
按照现有的标准，每个帧头需要整体发送完成后才能发送业务报文。以XGS-PON为例，帧头的长度＝4+8*B+48*P，其中，B为带宽映射表(bandwidth map，BWmap)个数，P为物理层操作管理和维护(Physical Layer Operations,Administration and Maintenance，PLOAM)消息个数。因此，帧头的长度可能为几十字节到几千字节不等，若需要发送的BWmap和PLOAM消息较多，会给业务报文的发送带来较大的时延。
发明内容
本申请提供了一种数据帧的分片方法、数据帧的解析方法及相关设备。如果帧头的长度超过指定长度，OLT将对帧头进行主动分片，分片的子帧头之间可以支持报文的抢占，降低了报文的传输时延。
第一方面，本申请提供了一种数据帧的分片方法。该方法包括：OLT生成原始数据帧，该原始数据帧包括帧头和报文。若帧头的长度大于第一预设值，则OLT对帧头进行分片以得到目标数据帧。帧头分片后的每个子帧头的长度小于或等于第一预设值。目标数据帧包括多个码字，至少一个码字包括第一字段，每个码字包括第二字段，至少一个码字还包括第三字段。其中，第一字段用于承载子帧头和低优先级的第一报文，第二字段用于承载校验码，第三字段用于承载高优先级的第二报文。第一报文的发送次序位于发送次序最靠前的子帧头之后，且第一报文的发送次序位于至少一个子帧头的发送次序之前。进而，OLT向光网络单元ONU发送目标数据帧。
在该实施方式中，如果帧头的长度超过指定长度，OLT将对帧头进行主动分片。分片后的每个子帧头的长度都不超过指定长度。并且，分片的子帧头之间可以支持报文的抢占。也 就是说，无需等整个帧头全部发送完成后才能发送报文，报文可以在任意的子帧头之间进行发送，降低了报文的传输时延。另外，在OLT生成的码字中除了包含承载帧头和低优先级报文的字段外，部分或者全部码字中还可以为高优先级报文预留字段，从而降低了高优先级报文的传输时延。
在一些可能的实施方式中，帧头为下行物理控制块(Physical Control Block downstream，PCBd)。为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用GPON的封装方式(GPON Encapsulation Mode，GEM)，而分片后位于起始位置的第一个子帧头仍采用分片之前的PCBd的格式。或者，帧头还可以为超帧(Superframe，FS)帧头。为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用XG-PON的封装方式(XG-PON Encapsulation Mode，XGEM)，而分片后位于起始位置的第一个子帧头仍采用分片之前的FS帧头的格式。
在一些可能的实施方式中，每个子帧头包括目标GEM端口标识或目标XGEM端口标识，OLT向ONU发送目标数据帧之前，方法还包括：OLT向ONU发送第一通知消息。其中，第一通知消息包括目标GEM端口标识或者目标XGEM端口标识。应理解，报文也需要采用GEM或XGEM进行封装，为了使ONU能够对报文和子帧头进行区分，需要为子帧头定义一个专用的目标GEM端口标识或目标XGEM端口标识，以区别于报文中的GEM端口标识或XGEM端口标识。OLT将目标GEM端口标识或目标XGEM端口标识预先发送给各ONU，可以使得ONU收到目标数据帧后可以顺利地对各子帧头进行解析。
在一些可能的实施方式中，ONU包括第一ONU和第二ONU，第一ONU支持对帧头进行分片，第二ONU不支持对帧头进行分片。其中，OLT向第一ONU发送的目标数据帧中每个子帧头包括带宽映射表(bandwidth map，BWmap)和下行物理层操作管理和维护(Physical Layer Operations,Administration and Maintenance downstream，PLOAMd)消息。OLT向第二ONU发送的目标子帧头包括BWmap和PLOAM消息，目标子帧头为目标数据帧中发送次序最靠前的子帧头。上述处理方式适用于新旧ONU同时存在的场景，可以兼容支持帧头分片的新ONU以及不支持分片的旧ONU，提高了本方案的实用性。
在一些可能的实施方式中，OLT向ONU发送目标数据帧之前，方法还包括：若第一报文的发送次序在第二报文的发送次序之前且第一报文的长度大于第二预设值，则OLT对第一报文进行分片。第一报文分片后的每个子报文的长度小于或等于第二预设值，第二报文的发送次序位于发送次序最靠前的子报文之后，且第二报文的发送次序位于至少一个子报文的发送次序之前。通过上述方式，对低优先级的第一报文分片后，支持高优先级的第二报文抢占位置，可以有效降低高优先级报文的传输时延。
在一些可能的实施方式中，每个子报文采用GEM或XGEM进行封装，以兼容现有标准，便于ONU对各子报文进行解析。
在一些可能的实施方式中，第三字段包括多个子字段，每个子字段用于承载第二报文中的部分报文。其中，不同子字段中可以承载着属于不同ONU的业务，进一步提高了本方案的实用性。
在一些可能的实施方式中，OLT向ONU发送目标数据帧之前，方法还包括：OLT向ONU发送第二通知消息，其中，第二通知消息用于指示与ONU对应的目标子字段以及目标子字段的 起始位置和长度。应理解，第三字段的整体采用GEM封装或XGEM封装，但是为了节省开销，每个子字段不再逐个进行GEM封装或XGEM封装。因此，OLT需要将各子字段的配置信息发送至各ONU，便于各ONU从各自对应的子字段中提取数据。
第二方面，本申请提供了一种数据帧的解析方法。该方法包括：ONU接收OLT发送的目标数据帧。其中，目标数据帧由OLT对原始数据帧的帧头进行分片得到。帧头分片后的每个子帧头的长度小于或等于第一预设值。目标数据帧包括多个码字，至少一个码字包括第一字段，每个码字包括第二字段，至少一个码字还包括第三字段。其中，第一字段用于承载子帧头和第一报文，第二字段用于承载校验码，第三字段用于承载第二报文。第一报文的优先级低于第二报文的优先级，第一报文的发送次序位于发送次序最靠前的子帧头之后，且第一报文的发送次序位于至少一个子帧头的发送次序之前。进而，ONU对目标数据帧中的码字依次进行解析。
在一些可能的实施方式中，帧头为PCBd，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用GEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的PCBd的格式。或者，帧头还可以为FS帧头，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用XGEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的FS帧头的格式。
在一些可能的实施方式中，每个子帧头包括目标GEM端口标识或目标XGEM端口标识，ONU接收OLT发送的目标数据帧之前，方法还包括：ONU接收OLT发送的第一通知消息。其中，第一通知消息包括目标GEM端口标识，目标GEM端口标识用于指示采用GEM封装的子帧头。或者，第一通知消息包括目标XGEM端口标识，目标XGEM端口标识用于指示采用XGEM封装的子帧头。
在一些可能的实施方式中，若ONU支持对帧头进行分片，则每个子帧头包括BWmap和PLOAM消息。若ONU不支持对帧头进行分片，则目标子帧头包括BWmap和PLOAM消息，目标子帧头为目标数据帧中发送次序最靠前的子帧头。
在一些可能的实施方式中，若第一报文的发送次序在第二报文的发送次序之前且第一报文的长度大于第二预设值，则第一报文由OLT分片为多个子报文，每个子报文的长度小于或等于第二预设值，第二报文的发送次序位于发送次序最靠前的子报文之后，且第二报文的发送次序位于至少一个子报文的发送次序之前。
在一些可能的实施方式中，每个子报文采用GEM或XGEM进行封装。
在一些可能的实施方式中，第三字段包括多个子字段，每个子字段用于承载第二报文中的部分报文。
在一些可能的实施方式中，ONU接收OLT发送的目标数据帧之前，方法还包括：ONU接收OLT发送的第二通知消息。其中，第二通知消息用于指示与ONU对应的目标子字段以及目标子字段的起始位置和长度。
第三方面，本申请提供了一种OLT。该OLT包括处理器和收发器，处理器和收发器通过线路互相连接，处理器用于执行第一方面中任意一种方法的部分或全部步骤。
在一些可能的实施方式中，OLT还包括存储器，处理器调用存储器中的程序代码用于执行第一方面中任意一种方法的部分或全部步骤。
第四方面，本申请提供了一种ONU。该ONU包括处理器和收发器，处理器和收发器通过线路互相连接，处理器用于执行第二方面中任意一种方法的部分或全部步骤。
在一些可能的实施方式中，ONU还包括存储器，处理器调用存储器中的程序代码用于执行第二方面中任意一种方法的部分或全部步骤。
第五方面，本申请提供了一种OLT。该OLT包括处理单元和收发单元。处理单元用于：生成原始数据帧，该原始数据帧包括帧头和报文。若帧头的长度大于第一预设值，则OLT对帧头进行分片以得到目标数据帧。帧头分片后的每个子帧头的长度小于或等于第一预设值。目标数据帧包括多个码字，至少一个码字包括第一字段，每个码字包括第二字段，至少一个码字还包括第三字段。其中，第一字段用于承载子帧头和低优先级的第一报文，第二字段用于承载校验码，第三字段用于承载高优先级的第二报文。第一报文的发送次序位于发送次序最靠前的子帧头之后，且第一报文的发送次序位于至少一个子帧头的发送次序之前。进而，收发单元用于OLT向光网络单元ONU发送目标数据帧。
在一些可能的实施方式中，帧头为PCBd，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用GEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的PCBd的格式。或者，帧头还可以为FS帧头，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用XGEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的FS帧头的格式。
在一些可能的实施方式中，每个子帧头包括目标GEM端口标识或目标XGEM端口标识。收发单元向ONU发送目标数据帧之前，收发单元还用于：向ONU发送第一通知消息。其中，第一通知消息包括目标GEM端口标识，目标GEM端口标识用于指示采用GEM封装的子帧头。或者，第一通知消息包括目标XGEM端口标识，目标XGEM端口标识用于指示采用XGEM封装的子帧头。
在一些可能的实施方式中，ONU包括第一ONU和第二ONU，第一ONU支持对帧头进行分片，第二ONU不支持对帧头进行分片。其中，OLT向第一ONU发送的目标数据帧中每个子帧头包括BWmap和PLOAM消息。OLT向第二ONU发送的目标子帧头包括BWmap和PLOAM消息，目标子帧头为目标数据帧中发送次序最靠前的子帧头。
在一些可能的实施方式中，收发单元向ONU发送目标数据帧之前，处理单元还用于：若第一报文的发送次序在第二报文的发送次序之前且第一报文的长度大于第二预设值，则对第一报文进行分片。第一报文分片后的每个子报文的长度小于或等于第二预设值，第二报文的发送次序位于发送次序最靠前的子报文之后，且第二报文的发送次序位于至少一个子报文的发送次序之前。
在一些可能的实施方式中，每个子报文采用GEM或XGEM进行封装。
在一些可能的实施方式中，第三字段包括多个子字段，每个子字段用于承载第二报文中的部分报文。
在一些可能的实施方式中，收发单元向ONU发送目标数据帧之前，收发单元还用于：向ONU发送第二通知消息。其中，第二通知消息用于指示与ONU对应的目标子字段以及目标子字段的起始位置和长度。
第六方面，本申请提供了一种ONU。该ONU包括处理单元和收发单元。收发单元用于： 接收光线路终端OLT发送的目标数据帧。其中，目标数据帧由OLT对原始数据帧的帧头进行分片得到，帧头分片后的每个子帧头的长度小于或等于第一预设值。目标数据帧包括多个码字，至少一个码字包括第一字段，每个码字包括第二字段，至少一个码字还包括第三字段。其中，第一字段用于承载子帧头和第一报文，第二字段用于承载校验码，第三字段用于承载第二报文。第一报文的优先级低于第二报文的优先级，第一报文的发送次序位于发送次序最靠前的子帧头之后，且第一报文的发送次序位于至少一个子帧头的发送次序之前。进而，处理单元用于对目标数据帧中的码字依次进行解析。
在一些可能的实施方式中，帧头为PCBd，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用GEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的PCBd的格式。或者，帧头还可以为FS帧头，为了使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用XGEM进行封装，而分片后位于起始位置的第一个子帧头仍采用分片之前的FS帧头的格式。
在一些可能的实施方式中，每个子帧头包括目标GEM端口标识或目标XGEM端口标识，收发单元接收OLT发送的目标数据帧之前，收发单元还用于：接收OLT发送的第一通知消息。其中，第一通知消息包括目标GEM端口标识，目标GEM端口标识用于指示采用GEM封装的子帧头。或者，第一通知消息包括目标XGEM端口标识，目标XGEM端口标识用于指示采用XGEM封装的子帧头。
在一些可能的实施方式中，若ONU支持对帧头进行分片，则每个子帧头包括BWmap和PLOAM消息。若ONU不支持对帧头进行分片，则目标子帧头包括BWmap和PLOAM消息，目标子帧头为目标数据帧中发送次序最靠前的子帧头。
在一些可能的实施方式中，若第一报文的发送次序在第二报文的发送次序之前且第一报文的长度大于第二预设值，则第一报文由OLT分片为多个子报文。每个子报文的长度小于或等于第二预设值，第二报文的发送次序位于发送次序最靠前的子报文之后，且第二报文的发送次序位于至少一个子报文的发送次序之前。
在一些可能的实施方式中，每个子报文采用GEM或XGEM进行封装。
在一些可能的实施方式中，第三字段包括多个子字段，每个子字段用于承载第二报文中的部分报文。
在一些可能的实施方式中，收发单元接收OLT发送的目标数据帧之前，收发单元还用于：接收OLT发送的第二通知消息。其中，第二通知消息用于指示与ONU对应的目标子字段以及目标子字段的起始位置和长度。
本申请实施例中，如果帧头的长度超过指定长度，OLT将对帧头进行主动分片。分片后的每个子帧头的长度都不超过指定长度。并且，分片的子帧头之间可以支持报文的抢占。也就是说，无需等整个帧头全部发送完成后才能发送报文，报文可以在任意的子帧头之间进行发送，降低了报文的传输时延。另外，在OLT生成的码字中除了包含承载帧头和低优先级报文的字段外，部分或者全部码字中还可以为高优先级报文预留字段，从而降低了高优先级报文的传输时延。
附图说明
图1为PON的***架构示意图；
图2为本申请中数据帧的分片方法的一个实施例示意图；
图3(a)为GPON标准中GTC帧的一种结构示意图；
图3(b)为XG-PON标准中FS帧的一种结构示意图；
图4(a)为GTC帧中PCBd分片后的一种结构示意图；
图4(b)为FS帧中FS帧头分片后的一种结构示意图；
图5为本申请实施例中OLT与ONU进行能力协商的一个实施例示意图；
图6为现有标准中FEC码字的结构示意图；
图7(a)为本申请实施例中FEC码字的第一种结构示意图；
图7(b)为本申请实施例中FEC码字的第二种结构示意图；
图7(c)为本申请实施例中FEC码字的第二种结构示意图；
图8为本申请实施例中OLT向ONU通知子字段配置信息的实施例示意图；
图9为本申请中数据帧的解析方法的一个实施例示意图；
图10为本申请实施例中一种可能的OLT的结构示意图；
图11为本申请实施例中另一种可能的OLT的结构示意图；
图12为本申请实施例中一种可能的ONU的结构示意图；
图13为本申请实施例中另一种可能的ONU的结构示意图。
具体实施方式
本申请提供了一种数据帧的分片方法、数据帧的解析方法及相关设备。如果帧头的长度超过指定长度，OLT将对帧头进行主动分片，分片的子帧头之间可以支持报文的抢占，降低了报文的传输时延。
本申请主要应用于无源光网络(passive optical network，PON)***中，下面对PON的***架构进行介绍。
图1为PON的***架构示意图。OLT连接上层的网络侧设备(如交换机、路由器等)，下层连接一个或者多个光分配网络(optical distribution network，ODN)。
ODN包括用于光功率分配的无源光分光器、连接在无源光分光器和OLT之间的主干光纤，以及连接在无源光分光器和ONU之间的分支光纤。下行传输数据时，ODN将OLT下行的数据通过分光器传输到各个ONU，ONU选择性接收携带自身标识的下行数据。上行传输数据时，ODN将N路ONU发送的光信号组合成一路光信号传输到OLT。如果ONU同时提供用户端口功能，如ONU提供以太网用户端口或者传统电话业务(plain old telephone service，POTS)用户端口，则称为光网络终端(optical network termination，ONT)。
在PON***应用的一些场景中，通常有低时延和低抖动的要求。因此，需要尽可能降低报文的传输时延，尤其是降低高优先级报文的传输时延。按照现有的标准，每个帧头需要整体发送完成后才能发送报文，如果帧头太长就会给报文的传输带来较大的时延。为此，本申 请提供了一种数据帧的分片方法，下面进行详细介绍。
图2为本申请中数据帧的分片方法的一个实施例示意图。在该示例中，数据帧的分片方法包括如下步骤。
201、OLT生成原始数据帧。
原始数据帧包括帧头和报文，其中，帧头位于原始数据帧中的起始位置。应理解，在不同的PON标准中，所采用的的帧头格式也会有一些差异。例如，在GPON标准中，帧头为下行物理控制块(Physical Control Block downstream，PCBd)。图3(a)为GPON标准中GTC帧的一种结构示意图。如图3(a)所示，PCBd包括物理同步序列(Physical synchronization sequence，Psync)、标识(Ident)、下行物理层操作管理和维护(Physical Layer Operations,Administration and Maintenance downstream，PLOAMd)、比特交叉奇偶校验(Bit Interleaved Parity，BIP)、下行净荷长度(Payload Length downstream，Plend)和带宽映射表(bandwidth map，BWmap)。超帧净荷(FS payload)用于承载报文。又例如，在XG-PON、XGS-PON、25G-PON或50G-PON等标准中，帧头为超帧(Superframe，FS)帧头。图3(b)为XG-PON标准中FS帧的一种结构示意图。如图3(b)所示，FS帧头包括下行帧头长度(Header Length downstream，Hlend)、BWmap和PLOAMd。GTC帧净荷用于承载报文。
在一些可能的实施方式中，原始数据帧中包括多种不同优先级的报文。例如，原始数据帧包括第一报文和第二报文，其中，第一报文为普通报文，第二报文为对时延更敏感的报文，即第一报文的优先级低于第二报文的优先级。
202、若帧头的长度大于第一预设值，则OLT对帧头进行分片得到目标数据帧。
本实施例中，如果帧头的长度太长，OLT可以主动将帧头分片成多个子帧头。其中，分片后的每个子帧头的长度要小于或等于第一预设值。并且，帧头分片后可以支持报文在各子帧头之间抢占位置，即报文的发送次序可以在至少一个子帧头的发送次序之前。应理解，帧头分片后的第一个子帧头还是位于数据帧的起始位置，因此报文的发送次序要在第一个子帧头的发送次序之后。需要说明的是，本申请不限定每个子帧头的具体长度，可以按照等分的方式进行分片，尽可能使每个子帧头的长度相同，或者，也可以随机调整每个子帧头的长度。上述第一预设值可以灵活配置，以FS帧头具有128个BWmap和64个PLOAMd为例，FS帧头的总长度为4100字节，若第一预设值设置为512字节，则可以将FS帧头分片为9个子帧头。如果第一个子帧头长度为512字节，那么最快只需要等待512字节的子帧头发送完后即可发送报文。
为了兼容现有标准，使得ONU能够解析分片后的子帧头，OLT需要对除第一个子帧头外的其他子帧头采用GPON的封装方式(GPON Encapsulation Mode，GEM)或XG-PON的封装方式(XG-PON Encapsulation Mode，XGEM)。而分片后位于起始位置的第一个子帧头仍采用分片之前的帧头格式。图4(a)为GTC帧中PCBd分片后的一种结构示意图。如图4(a)所示，子帧头1采用PCBd分片之前的帧头格式，子帧头2采用GEM进行封装，报文的位置位于子帧头1和子帧头2之间。每个子帧头中通过Plend来指示BWmap的数量，由于Plend不支持纠错，所以每个子帧头中需要重复发送2次Plend，ONU可以选择循环冗余校验(Cyclic Redundancy Check，CRC)正确的Plend使用。图4(b)为FS帧中FS帧头分片后的一种结 构示意图。如图4(b)所示，子帧头1采用FS帧头分片之前的帧头格式，子帧头2采用XGEM进行封装，报文的位置位于子帧头1和子帧头2之间。每个子帧头中的Hlend用于指示PLOAMd的数量和BWmap的数量。通过对比可以看出，PCBd分片后只在第一个子帧头发送PLOAMd和BWmap，其他的子帧头只需要发送BWmap。而FS帧头分片后的每个子帧头都支持发送PLOAMd和BWmap，分片后的子帧头可以只发送PLOAMd，也可以只发送BWmap，或者同时发送PLOAMd和BWmap。
需要说明的是，每个采用GEM进行封装的子帧头都具有GEM端口标识(GEM Port ID)，其中，GEM端口标识位于如图4(a)所示的GEM帧头中。同理，每个采用XGEM进行封装的子帧头都具有XGEM端口标识(XGEM Port ID)，其中，XGEM端口标识位于如图4(b)所示的XGEM帧头中。应理解，报文也需要采用GEM或XGEM进行封装，为了使ONU能够对报文和子帧头进行区分，需要为子帧头定义一个专用的GEM Port ID或XGEM Port ID，以区别于报文中的GEM Port ID或XGEM Port ID。为了使各ONU能提前获知采用GEM或XGEM封装的子帧头，OLT需要将专用的GEM Port ID或XGEM Port ID预先发送给各ONU。具体地，OLT可以向各ONU发送第一通知消息，第一通知消息中包括专用的GEM Port ID或XGEM Port ID。待OLT收到ONU发送的响应消息后，即可将帧头分片后的目标数据帧发送至ONU。
在一些可能的实施方式，并不是所有的ONU都支持帧头分片，对于支持帧头分片的ONU和不支持帧头分片的ONU在处理方式上会有一定差异，需要OLT和ONU之间进行能力协商，下面进行说明。
图5为本申请实施例中OLT与ONU进行能力协商的一个实施例示意图。
501、OLT向ONU发送注册上线消息。
由于OLT还不确定ONU是否支持帧头分片，因此，OLT将通过帧头分片后的第一个子帧头向ONU发送与注册上线相关的PLOAMd和BWmap。这样一来，即使ONU不支持帧头分片也能通过第一个子帧头解析OLT发送的注册上线消息。
502、ONU向OLT发送上行光信号。
OLT可以通过ONU发送的上行光信号获取ONU的序列号(Serial Number，SN)，OLT就可以为ONU分配对应的身份标识(Identity document，ID)。进而，OLT还将对ONU进行测距，并为ONU分配对应的上行传输时隙，已完成ONU的注册。
503、OLT向ONU发送能力协商消息。
OLT通过向ONU发送能力协商消息，用于指示ONU上报自身是否支持OLT对帧头进行分片。
504、ONU向OLT发送能力协商的应答。
ONU收到OLT发送的能力协商消息后，会将自身是否具有支持帧头分片的能力上报给OLT。
505、OLT判断ONU是否支持帧头分片，若否，则执行步骤506，若是，则执行步骤507。
506、OLT通过第一个子帧头向ONU发送PLOAMd和BWmap。
若ONU不支持帧头分片，即说明ONU无法解析采用GEM或XGEM封装的子帧头。那么，OLT将通过第一个子帧头向ONU发送PLOAMd和BWmap。
507、OLT向ONU发送专用的GEM Port ID或XGEM Port ID。
若ONU支持帧头分片，即说明ONU可以解析采用GEM或XGEM封装的子帧头。那么，ONU 就需要将专用的GEM Port ID或XGEM Port ID预先发送至ONU，以使得ONU可以顺利解析各子帧头。具体地，OLT可以通过PLOAM消息或光网络单元管理控制接口(ONU Management and Control Interface，OMCI)消息向ONU发送专用的GEM Port ID或XGEM Port ID。
508、ONU向OLT发送响应消息。
ONU通过向OLT发送响应消息以告知自身已经收到了专用的GEM Port ID或XGEM Port ID。需要说明的是，OLT在收到ONU发送的响应消息之前，仍然只会通过第一个子帧头向ONU发送PLOAMd和BWmap。在OLT收到ONU发送的响应之后，OLT就可以通过帧头分片后的多个子帧头向ONU发送PLOAMd和BWmap。
应理解，上述处理方式适用于新旧ONU同时存在的场景，可以兼容支持帧头分片的新ONU以及不支持分片的旧ONU。当然，在一些特定场景中，如果所有ONU都支持帧头分片，那么OLT也可以不跟ONU进行能力协商，直接将专用的GEM Port ID或XGEM Port ID发送至ONU。
在一些可能的实施方式中，如果报文中低优先级的第一报文的发送次序在高优先级的第二报文的发送次序之前，且第一报文的长度大于第二阈值，则OLT还可以主动对第一报文进行分片。第一报文分片后得到多个子报文，第二报文可以在各子报文之间抢占位置，即第二报文的发送次序可以在至少一个子报文的发送次序之前。通过上述方式，可以有效降低高优先级报文的传输时延。应理解，为了兼容现有标准，使得ONU能够解析分片后的子报文，每个子报文也需要采用GEM或XGEM进行封装。
需要说明的是，OLT在向ONU发送目标数据帧之前还需要对目标数据帧进行前向纠错(Forward Error Correction，FEC)编码。经过FEC编码后的目标数据帧包括多个码字(codeword)。图6为现有标准中FEC码字的结构示意图。如图6所示，对一个超帧进行FEC编码后可以形成N个码字，每个码字包括字段1和字段2。其中，字段1用于承载超帧帧头和/或报文，字段2用于承载校验码。进而，N个码字和下行物理同步块(downstream physical synchronization block，PSBd)构成PHY帧，PHY帧的净荷区用于承载N个码字。需要说明的是，上述每个码字中的多个字段也可以理解为划分为多个时隙，不同的时隙用于传输不同的信息。应理解，图6所示的方案中并不是每个码字都能传输高优先级报文，为了降低高优先级报文的传输时延，本申请考虑在码字中预留专门用于承载高优先级报文的字段，这样一来就可以为高优先级报文提供确定性的传输时延，下面进行进一步介绍。
图7(a)为本申请实施例中FEC码字的第一种结构示意图。如图7(a)所示，经过FEC编码后的目标数据帧包括N个码字。每个码字都包括字段1、字段2和字段3。其中，字段1用于承载分片后的子帧头和/或低优先级的第一报文，字段2用于承载校验码，字段3用于承载高优先级的第二报文。需要说明的是，每个码字中字段1和字段3的长度可以是固定的，也可以是变化的，具体此处不做限定。并且，每个码字中字段1和字段3的相对位置可以是固定，也可以是变化的，具体此处不做限定。例如，前一个码字中字段1的位置可以在字段3之前，后一个码字中字段3的位置可以在字段1之前。
图7(b)为本申请实施例中FEC码字的第二种结构示意图。如图7(b)所示，并不是每个码字中都需要预留字段3，可以根据实际需要以M个码字为周期来配置字段3。例如，码字1中配置有字段3，那么下一个配置有字段3的码字为码字M+1。需要说明的是，本申请不限定M的取值。其中，M的取值越小，可以更好地降低高优先级报文务的传输时延，但是也会 占用较多的资源。因此，可以根据实际需求来灵活设置M的取值。
需要说明的是，在实际应用中，每个码字都需要包括用于承载校验码的字段2。码字1一定包括用来承载帧头的字段1，可选地，码字1还可以包括字段3。除了码字1之外的其他码字可以只包括字段1和字段2，或者，也可以只包括字段2和字段3，又或者，还可以同时包括字段1、字段2和字段3。
图7(c)为本申请实施例中FEC码字的第二种结构示意图。如图7(c)所示，本申请实施例还可以在上述字段3的基础上进一步划分多个子字段，每个子字段用于承载第二报文中的部分报文，本申请不限定字段3划分出的子字段的数量以及每个子字段的长度。应理解，字段3的整体采用GEM封装或XGEM封装，但是为了节省开销，每个子字段不再逐个进行GEM封装或XGEM封装。因此，为了便于各ONU从各自对应的子字段中提取数据，OLT需要将各子字段的配置信息发送至各ONU，下面进行说明。
图8为本申请实施例中OLT向ONU通知子字段配置信息的实施例示意图。
801、OLT向ONU发送子字段的配置信息。
具体地，OLT可以通过PLOAM消息或OMCI消息向ONU发送子字段的配置信息。其中，配置信息包括与该ONU对应的目标子字段的起始位置和长度。应理解，不同子字段中可以承载着属于不同ONU的业务，因此，OLT需要通知各ONU与之对应的子字段的起始位置和长度，以便于各ONU从自身对应的子字段中提取业务。
802、ONU向OLT发送响应消息，以确认收到子字段的配置信息。
803、OLT向ONU发送目标数据帧。
OLT将通过目标数据帧中的子字段来向ONU发送高优先级业务。
804、OLT向ONU发送更新后的子字段的配置信息。
在一些可能的实施方式中，上述字段3中各子字段的配置信息可能会发生变化，那么，OLT需要将更新后的子字段的配置信息发送给ONU。
805、ONU向OLT发送响应消息，以确认收到更新后的子字段的配置信息。
806、OLT向ONU发送更新后的目标数据帧。
203、OLT向ONU发送目标数据帧。
应理解，在OLT完成了上述步骤202中介绍的对原始数据帧的各种处理方式后，OLT会将得到的目标数据帧发送至ONU。
本申请实施例中，如果帧头的长度超过指定长度，OLT将对帧头进行主动分片。分片后的每个子帧头的长度都不超过指定长度。并且，分片的子帧头之间可以支持报文的抢占。也就是说，无需等整个帧头全部发送完成后才能发送报文，报文可以在任意的子帧头之间进行发送，降低了报文的传输时延。另外，在OLT生成的码字中除了包含承载帧头和低优先级报文的字段外，部分或者全部码字中还可以为高优先级报文预留字段，从而降低了高优先级报文的传输时延。
上面对OLT执行的数据帧的分片方法进行了介绍，下面对ONU执行的数据帧的解析方法进行介绍。
图9为本申请中数据帧的解析方法的一个实施例示意图。在该示例中，数据帧的解析方 法包括如下步骤。
901、ONU接收OLT发送的目标数据帧。
具体地，关于目标数据中的介绍可以参考上述图2所示实施例中步骤202的相关描述，此处不再赘述。
902、ONU对目标数据帧中的码字依次进行解析。
本实施例中，由于码字中的子帧头都采用了GEM或XGEM进行封装，并且ONU可以预先接收到OLT发送的专用的GEM Port ID或XGEM Port ID。因此，ONU根据专用的GEM Port ID或XGEM Port ID可以顺利地对各子帧头进行解析。关于OLT向ONU发送专用的GEM Port ID或XGEM Port ID的介绍，可以参考上述图5所示的实施例，此处不再赘述。
另外，若码字中的字段3进一步划分出了多个子字段，ONU还可以预先接收到OLT发送的子字段的配置信息。ONU根据该配置信息即可获知自身对应的子字段的起始位置和长度，从而可以顺利地对字段3中各子字段进行解析。关于OLT向ONU发送子字段配置信息的介绍，可以参考上述图8所示的实施例，此处不再赘述。
下面对本申请提供的OLT和ONU进行介绍。
图10为本申请实施例中一种可能的OLT的结构示意图。该OLT包括处理单元1001和收发单元1002。具体地，处理单元1001用于执行上述图2所示实施例中的步骤201和步骤202。收发单元1002用于执行上述图2所示实施例中的步骤203。在一些可能的实施方式中，收发单元1002还用于执行上述图5和图8所示实施例中与ONU进行信息交互的步骤。
图11为本申请实施例中另一种可能的OLT的结构示意图。该OLT包括处理器1101和收发器1102，处理器1101与收发器1102通过线路相互连接。需要说明的是，收发器1102用于执行上述图2、图5和图8所示实施例中OLT进行信息收发的操作。处理器1101用于执行上述图2、图5和图8所示实施例中除信息收发外OLT的其他操作。在一些可能的实施方式中，处理器1101包括上述的处理单元1001，收发器1102包括上述的收发单元1002。可选地，OLT还可以包括存储器1103，其中，存储器1103用于存储程序指令和数据。
图12为本申请实施例中一种可能的ONU的结构示意图。该ONU包括处理单元1201和收发单元1202。具体地，处理单元1201用于执行上述图9所示实施例中的步骤902。收发单元1202用于执行上述图9所示实施例中的步骤901。在一些可能的实施方式中，收发单元1202还用于执行上述图5和图8所示实施例中与OLT进行信息交互的步骤。
图13为本申请实施例中另一种可能的ONU的结构示意图。该ONU包括处理器1301和收发器1302，处理器1301与收发器1302通过线路相互连接。需要说明的是，收发器1302用于执行上述图9、图5和图8所示实施例中ONU进行信息收发的操作。处理器1301用于执行上述图9、图5和图8所示实施例中除信息收发外ONU的其他操作。在一些可能的实施方式中，处理器1301包括上述的处理单元1201，收发器1302包括上述的收发单元1202。可选地，ONU还可以包括存储器1303，其中，存储器1303用于存储程序指令和数据。
需要说明的是，上述图11和图13中所示的处理器可以采用通用的中央处理器(Central Processing Unit，CPU)，微处理器，应用专用集成电路ASIC，或者至少一个集成电路，用于执行相关程序，以实现本申请实施例所提供的技术方案。上述图11和图13中所示的存储器可以存储操作***和其他应用程序。在通过软件或者固件来实现本申请实施例提供的技术 方案时，用于实现本申请实施例提供的技术方案的程序代码保存在存储器中，并由处理器来执行。在一实施例中，处理器内部可以包括存储器。在另一实施例中，处理器和存储器是两个独立的结构。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的***，装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，随机接入存储器等。具体地，例如：上述处理单元或处理器可以是中央处理器，通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现场可编程门阵列(FPGA)或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。上述的这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
当使用软件实现时，上述实施例描述的方法步骤可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘Solid State Disk(SSD))等。

Claims (36)

  1. 一种数据帧的分片方法，其特征在于，包括：
    光线路终端OLT生成原始数据帧，所述原始数据帧包括帧头和报文，所述报文包括第一报文和第二报文，所述第一报文的优先级低于所述第二报文的优先级；
    若所述帧头的长度大于第一预设值，则所述OLT对所述帧头进行分片以得到目标数据帧，所述帧头分片后的每个子帧头的长度小于或等于所述第一预设值，所述目标数据帧包括多个码字，至少一个所述码字包括第一字段，每个所述码字包括第二字段，至少一个所述码字还包括第三字段，其中，所述第一字段用于承载所述子帧头和所述第一报文，所述第二字段用于承载校验码，所述第三字段用于承载所述第二报文，所述第一报文的发送次序位于发送次序最靠前的子帧头之后，且所述第一报文的发送次序位于至少一个子帧头的发送次序之前；
    所述OLT向光网络单元ONU发送所述目标数据帧。
  2. 根据权利要求1所述的方法，其特征在于，所述帧头为下行物理控制块PCBd，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用千兆比特无源光网络的封装方式GEM进行封装；
    或，
    所述帧头为超帧FS帧头，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用10吉比特每秒无源光网络的封装方式XGEM进行封装。
  3. 根据权利要求2所述的方法，每个所述子帧头包括目标GEM端口标识或目标XGEM端口标识，其特征在于，所述OLT向所述ONU发送所述目标数据帧之前，所述方法还包括：
    所述OLT向所述ONU发送第一通知消息，其中，所述第一通知消息包括所述目标GEM端口标识，所述目标GEM端口标识用于指示采用GEM封装的子帧头，或者，所述第一通知消息包括所述目标XGEM端口标识，所述目标XGEM端口标识用于指示采用XGEM封装的子帧头。
  4. 根据权利要求1至3中任一项所述的方法，所述ONU包括第一ONU和第二ONU，第一ONU支持对所述帧头进行分片，所述第二ONU不支持对所述帧头进行分片，其中，所述OLT向所述第一ONU发送的目标数据帧中每个子帧头包括带宽映射表BWmap和物理层操作管理和维护PLOAM消息，所述OLT向所述第二ONU发送的目标子帧头包括BWmap和PLOAM消息，所述目标子帧头为所述目标数据帧中发送次序最靠前的子帧头。
  5. 根据权利要求1至4中任一项所述的方法，其特征在于，所述OLT向所述ONU发送所述目标数据帧之前，所述方法还包括：
    若所述第一报文的发送次序在所述第二报文的发送次序之前且所述第一报文的长度大于第二预设值，则所述OLT对所述第一报文进行分片，所述第一报文分片后的每个子报文的长度小于或等于所述第二预设值，所述第二报文的发送次序位于发送次序最靠前的子报文之后，且所述第二报文的发送次序位于至少一个子报文的发送次序之前。
  6. 根据权利要求5所述的方法，其特征在于，每个所述子报文采用GEM或XGEM进行封装。
  7. 根据权利要求1至6中任一项所述的方法，其特征在于，所述第三字段包括多个子字段，每个所述子字段用于承载所述第二报文中的部分报文。
  8. 根据权利要求7所述的方法，其特征在于，所述OLT向所述ONU发送所述目标数据帧 之前，所述方法还包括：
    所述OLT向所述ONU发送第二通知消息，其中，所述第二通知消息用于指示与所述ONU对应的目标子字段以及所述目标子字段的起始位置和长度。
  9. 一种数据帧的解析方法，其特征在于，包括：
    光网络单元ONU接收光线路终端OLT发送的目标数据帧，其中，所述目标数据帧由所述OLT对原始数据帧的帧头进行分片得到，所述帧头分片后的每个子帧头的长度小于或等于第一预设值，所述目标数据帧包括多个码字，至少一个所述码字包括第一字段，每个所述码字包括第二字段，至少一个所述码字还包括第三字段，其中，所述第一字段用于承载所述子帧头和第一报文，所述第二字段用于承载校验码，所述第三字段用于承载第二报文，所述第一报文的优先级低于所述第二报文的优先级，所述第一报文的发送次序位于发送次序最靠前的子帧头之后，且所述第一报文的发送次序位于至少一个子帧头的发送次序之前；
    所述ONU对所述目标数据帧中的码字依次进行解析。
  10. 根据权利要求9所述的方法，其特征在于，所述帧头为下行物理控制块PCBd，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用千兆比特无源光网络的封装方式GEM；
    或，
    所述帧头为超帧FS帧头，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用10吉比特每秒无源光网络的封装方式XGEM进行封装。
  11. 根据权利要求10所述的方法，其特征在于，每个所述子帧头包括目标GEM端口标识或目标XGEM端口标识，所述ONU接收所述OLT发送的所述目标数据帧之前，所述方法还包括：
    所述ONU接收所述OLT发送的第一通知消息，其中，所述第一通知消息包括所述目标GEM端口标识，所述目标GEM端口标识用于指示采用GEM封装的子帧头，或者，所述第一通知消息包括所述目标XGEM端口标识，所述目标XGEM端口标识用于指示采用XGEM封装的子帧头。
  12. 根据权利要求9至11中任一项所述的方法，其特征在于，若所述ONU支持对所述帧头进行分片，则每个所述子帧头包括带宽映射表BWmap和物理层操作管理和维护PLOAM消息；
    若所述ONU不支持对所述帧头进行分片，则目标子帧头包括BWmap和PLOAM消息，所述目标子帧头为所述目标数据帧中发送次序最靠前的子帧头。
  13. 根据权利要求9至12中任一项所述的方法，其特征在于，若所述第一报文的发送次序在所述第二报文的发送次序之前且所述第一报文的长度大于第二预设值，则所述第一报文由所述OLT分片为多个子报文，每个所述子报文的长度小于或等于第二预设值，所述第二报文的发送次序位于发送次序最靠前的子报文之后，且所述第二报文的发送次序位于至少一个子报文的发送次序之前。
  14. 根据权利要求13所述的方法，其特征在于，每个所述子报文采用GEM或XGEM进行封装。
  15. 根据权利要求9至14中任一项所述的方法，其特征在于，所述第三字段包括多个子字段，每个所述子字段用于承载所述第二报文中的部分报文。
  16. 根据权利要求15所述的方法，其特征在于，所述ONU接收所述OLT发送的所述目标 数据帧之前，所述方法还包括：
    所述ONU接收所述OLT发送的第二通知消息，其中，所述第二通知消息用于指示与所述ONU对应的目标子字段以及所述目标子字段的起始位置和长度。
  17. 一种光线路终端OLT，其特征在于，包括：处理器和收发器，所述处理器和所述收发器通过线路互相连接，所述处理器用于执行如权利要求1至8中任一项所述的方法。
  18. 根据权利要求17所述的OLT，其特征在于，所述OLT还包括存储器，所述处理器调用所述存储器中的程序代码用于执行如权利要求1至8中任一项所述的方法。
  19. 一种光网络单元ONU，其特征在于，包括：处理器和收发器，所述处理器和所述收发器通过线路互相连接，所述处理器用于执行如权利要求9至16中任一项所述的方法。
  20. 根据权利要求19所述的ONU，其特征在于，所述ONU还包括存储器，所述处理器调用所述存储器中的程序代码用于执行如权利要求9至16中任一项所述的方法。
  21. 一种光线路终端OLT，其特征在于，所述OLT包括处理单元和收发单元；
    所述处理单元用于：
    生成原始数据帧，所述原始数据帧包括帧头和报文，所述报文包括第一报文和第二报文，所述第一报文的优先级低于所述第二报文的优先级；
    若所述帧头的长度大于第一预设值，则对所述帧头进行分片以得到目标数据帧，所述帧头分片后的每个子帧头的长度小于或等于所述第一预设值，所述目标数据帧包括多个码字，至少一个所述码字包括第一字段，每个所述码字包括第二字段，至少一个所述码字还包括第三字段，其中，所述第一字段用于承载所述子帧头和所述第一报文，所述第二字段用于承载校验码，所述第三字段用于承载所述第二报文，所述第一报文的发送次序位于发送次序最靠前的子帧头之后，且所述第一报文的发送次序位于至少一个子帧头的发送次序之前；
    所述收发单元用于：向光网络单元ONU发送所述目标数据帧。
  22. 根据权利要求21所述的OLT，其特征在于，所述帧头为下行物理控制块PCBd，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用千兆比特无源光网络的封装方式GEM；
    或，
    所述帧头为超帧FS帧头，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用10吉比特每秒无源光网络的封装方式XGEM进行封装。
  23. 根据权利要求22所述的OLT，其特征在于，每个所述子帧头包括目标GEM端口标识或目标XGEM端口标识，其特征在于，所述收发单元向所述ONU发送所述目标数据帧之前，所述收发单元还用于：
    向所述ONU发送第一通知消息，其中，所述第一通知消息包括所述目标GEM端口标识，所述目标GEM端口标识用于指示采用GEM封装的子帧头，或者，所述第一通知消息包括所述目标XGEM端口标识，所述目标XGEM端口标识用于指示采用XGEM封装的子帧头。
  24. 根据权利要求21至23中任一项所述的OLT，其特征在于，所述ONU包括第一ONU和第二ONU，第一ONU支持对所述帧头进行分片，所述第二ONU不支持对所述帧头进行分片，其中，所述OLT向所述第一ONU发送的目标数据帧中每个子帧头包括带宽映射表BWmap和物 理层操作管理和维护PLOAM消息，所述OLT向所述第二ONU发送的目标子帧头包括BWmap和PLOAM消息，所述目标子帧头为所述目标数据帧中发送次序最靠前的子帧头。
  25. 根据权利要求21至24中任一项所述的OLT，其特征在于，所述收发单元向所述ONU发送所述目标数据帧之前，所述处理单元还用于：
    若所述第一报文的发送次序在所述第二报文的发送次序之前且所述第一报文的长度大于第二预设值，则对所述第一报文进行分片，所述第一报文分片后的每个子报文的长度小于或等于所述第二预设值，所述第二报文的发送次序位于发送次序最靠前的子报文之后，且所述第二报文的发送次序位于至少一个子报文的发送次序之前。
  26. 根据权利要求25所述的OLT，其特征在于，每个所述子报文采用GEM或XGEM进行封装。
  27. 根据权利要求21至26中任一项所述的OLT，其特征在于，所述第三字段包括多个子字段，每个所述子字段用于承载所述第二报文中的部分报文。
  28. 根据权利要求27所述的OLT，其特征在于，所述收发单元向所述ONU发送所述目标数据帧之前，所述收发单元还用于：
    向所述ONU发送第二通知消息，其中，所述第二通知消息用于指示与所述ONU对应的目标子字段以及所述目标子字段的起始位置和长度。
  29. 一种光网络单元ONU，其特征在于，包括处理单元和收发单元；
    所述收发单元用于：接收光线路终端OLT发送的目标数据帧，其中，所述目标数据帧由所述OLT对原始数据帧的帧头进行分片得到，所述帧头分片后的每个子帧头的长度小于或等于第一预设值，所述目标数据帧包括多个码字，至少一个所述码字包括第一字段，每个所述码字包括第二字段，至少一个所述码字还包括第三字段，其中，所述第一字段用于承载所述子帧头和第一报文，所述第二字段用于承载校验码，所述第三字段用于承载第二报文，所述第一报文的优先级低于所述第二报文的优先级，所述第一报文的发送次序位于发送次序最靠前的子帧头之后，且所述第一报文的发送次序位于至少一个子帧头的发送次序之前；
    所述处理单元用于：对所述目标数据帧中的码字依次进行解析。
  30. 根据权利要求29所述的ONU，其特征在于，所述帧头为下行物理控制块PCBd，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用千兆比特无源光网络的封装方式GEM；
    或，
    所述帧头为超帧FS帧头，所述目标数据帧中除了发送次序最靠前的子帧头外的其他所有子帧头都采用10吉比特每秒无源光网络的封装方式XGEM进行封装。
  31. 根据权利要求30所述的ONU，其特征在于，每个所述子帧头包括目标GEM端口标识或目标XGEM端口标识，所述收发单元接收所述OLT发送的目标数据帧之前，所述收发单元还用于：
    接收所述OLT发送的第一通知消息，其中，所述第一通知消息包括所述目标GEM端口标识，所述目标GEM端口标识用于指示采用GEM封装的子帧头，或者，所述第一通知消息包括所述目标XGEM端口标识，所述目标XGEM端口标识用于指示采用XGEM封装的子帧头。
  32. 根据权利要求29至31中任一项所述的ONU，其特征在于，若所述ONU支持对所述帧头进行分片，则每个所述子帧头包括带宽映射表BWmap和物理层操作管理和维护PLOAM消息；
    若所述ONU不支持对所述帧头进行分片，则目标子帧头包括BWmap和PLOAM消息，所述目标子帧头为所述目标数据帧中发送次序最靠前的子帧头。
  33. 根据权利要求29至32中任一项所述的ONU，其特征在于，若所述第一报文的发送次序在所述第二报文的发送次序之前且所述第一报文的长度大于第二预设值，则所述第一报文由所述OLT分片为多个子报文，每个所述子报文的长度小于或等于第二预设值，所述第二报文的发送次序位于发送次序最靠前的子报文之后，且所述第二报文的发送次序位于至少一个子报文的发送次序之前。
  34. 根据权利要求33所述的ONU，其特征在于，每个所述子报文采用GEM或XGEM进行封装。
  35. 根据权利要求29至34中任一项所述的ONU，其特征在于，所述第三字段包括多个子字段，每个所述子字段用于承载所述第二报文中的部分报文。
  36. 根据权利要求35所述的ONU，其特征在于，所述收发单元接收所述OLT发送的目标数据帧之前，所述收发单元还用于：
    接收所述OLT发送的第二通知消息，其中，所述第二通知消息用于指示与所述ONU对应的目标子字段以及所述目标子字段的起始位置和长度。
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CN106717017A (zh) * 2014-09-29 2017-05-24 华为技术有限公司 一种波分复用无源光网络通信的方法、装置及***
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