CN111133694B

CN111133694B - Data packet processing method, optical line terminal, optical network unit and system

Info

Publication number: CN111133694B
Application number: CN201780095254.8A
Authority: CN
Inventors: 李胜平; 吴朝; 陶明慧; 周军; 景磊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-09-25
Filing date: 2017-09-25
Publication date: 2021-10-15
Anticipated expiration: 2037-09-25
Also published as: CN111133694A; WO2019056371A1

Abstract

The invention discloses a data packet processing method, an optical line terminal, an optical network unit and a system. The method comprises the following steps: the optical line terminal generates and sends a data packet, the data packet comprises a preamble and an Ethernet packet, the preamble comprises a logical link identifier and a first field, and the first field is used for indicating at least one of a data rate and a modulation mode adopted by the optical line terminal for sending the Ethernet packet. The optical network unit receives the data packet and analyzes the preamble to obtain a logical link identifier and a first field; and when the logical link identification is matched with the optical network unit, the optical network unit demodulates the Ethernet packet according to the data rate or the modulation mode indicated by the first field and analyzes the demodulated Ethernet packet. Therefore, the optical line terminal can send each data packet on the same waveband, and when the ONU with multiple modulation modes exists in the upgraded PON system, the defects of overlarge complexity and overlarge insertion loss of an optical component caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

Description

Data packet processing method, optical line terminal, optical network unit and system

Technical Field

The present invention relates to the field of optical communication technologies, and in particular, to a data packet processing method, an optical line terminal, an optical network unit, and a system.

Background

Passive Optical Network (PON) technology is a point-to-multipoint Optical fiber access technology. The PON system may include an Optical Line Terminal (OLT), an Optical Distribution Network (ODN), and at least one Optical Network Unit (ONU). The OLT is connected with the ODN, and the ODN is connected with the ONU.

In the process of upgrading the PON system, the following requirements are generally required: for users without upgrading requirements, the ONU equipment of the users does not need to be changed; for users with upgrading requirements, new ONU equipment can be replaced, and the upgraded PON system can be compatible with the ONU which is not upgraded. In order to meet the above requirements, when a PON system is upgraded, a wavelength division coexistence method is generally used. That is, the uplink and downlink wavelengths used for communication between the OLT and the non-upgraded ONU are different from the uplink and downlink wavelengths used for communication between the OLT and the upgraded ONU.

However, with the continuous updating and upgrading of the PON, the types of ONUs of different generations in the PON system are increasing, and the number of wavelengths used in the wavelength division multiplexing is also increasing, so that the optical components of the OLT and the ONUs are complicated to implement, and the insertion loss is increased.

Disclosure of Invention

The embodiment of the invention provides a data packet processing method, an optical line terminal, an optical network unit and a passive optical network system, aiming at reducing the complexity and insertion loss of optical components and realizing smooth upgrading in an upgraded PON system.

In a first aspect, a method for processing a data packet is provided, where the method includes: the optical line terminal generates a data packet, wherein the data packet comprises a preamble and an Ethernet packet; the optical line terminal sends the data packet; the preamble includes a first field, where the first field is used to indicate at least one of a data rate and a modulation scheme used by the olt to send the ethernet packet.

In the method provided in the first aspect, the olt may send each data packet on the same band, and each onu may identify a preamble of each data packet, determine, according to the preamble, a modulation method of the ethernet packet corresponding to the logical link identifier of the onu, and may demodulate the ethernet packet according to a correct demodulation method. Therefore, when the PON system after upgrading has the optical network units with various modulation modes, the defects of overlarge complexity and overlarge insertion loss of optical components caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

According to the first aspect, in a first possible implementation manner of the data packet processing method, the preamble further includes a logical link identifier, and a data rate and a modulation method used for sending the ethernet packet are a data rate and a modulation method supported by an optical network unit corresponding to the logical link identifier.

According to the first aspect or the first possible implementation manner of the first aspect, in a second possible implementation manner of the packet processing method, the olt sends the preamble according to the lowest data rate or the lowest level modulation manner of each ONU that communicates with the olt, so that all ONUs in the PON system can correctly recognize the preamble; or, the optical line terminal sends the preamble according to a preset data rate or a modulation mode, so that the digital optical network unit can demodulate the preamble by adopting a correct demodulation mode.

In a second aspect, a method for processing a data packet is provided, the method comprising: an optical network unit receives a data packet, wherein the data packet comprises a preamble and an Ethernet packet, the preamble comprises a logical link identifier and a first field, and the first field is used for indicating at least one of a data rate and a modulation mode adopted by an optical line terminal for sending the Ethernet packet; the optical network unit analyzes the preamble to obtain the logical link identifier and a first field; and when the logical link identification is matched with the optical network unit, the optical network unit demodulates the Ethernet packet according to the data rate or the modulation mode indicated by the first field and analyzes the demodulated Ethernet packet.

In the method provided in the second aspect, the olt may send each data packet on the same band, and each onu may identify a preamble of each data packet, determine, according to the preamble, a modulation method of the ethernet packet corresponding to its own logical link identifier, and may demodulate the ethernet packet according to a correct demodulation method. Therefore, when the PON system after upgrading has the optical network units with various modulation modes, the defects of overlarge complexity and overlarge insertion loss of optical components caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

According to the second aspect, in a first possible implementation manner of the packet processing method, the parsing, by the onu, the preamble includes: the optical network unit demodulates the preamble according to the data rate or the modulation mode of the optical network unit and analyzes the demodulated preamble;

for the analog optical network unit, if the level of the modulation mode adopted by the optical line terminal for sending the preamble is equal to the level of the modulation mode of the analog optical network unit, the optical network unit can directly demodulate and obtain correct data. For the analog optical network unit, if the level of the modulation mode adopted by the optical line terminal to send the preamble is lower than the level of the modulation mode of the analog optical network unit, the optical network unit needs to convert the demodulated preamble to restore the correct original data. The realization mode enables each optical network unit to adopt a correct demodulation mode to demodulate the preamble.

Specifically, the step of converting the demodulated preamble by the analog optical network unit includes: converting each bit group in the demodulated preamble into a bit sequence containing M bits; the bit number of each bit group is the bit number expressed by each symbol period under the modulation mode level corresponding to the optical network unit; m is the number of bits represented by each symbol period at the level of the modulation scheme used to transmit the preamble. The conversion mode enables the optical network unit of the high-level modulation mode to still correctly analyze the data transmitted by the low-level modulation mode.

According to the second aspect, in a second possible implementation manner of the packet processing method, the parsing, by the onu, the preamble includes: and the optical network unit demodulates the preamble according to a preset data rate or a modulation mode and analyzes the demodulated preamble. The preset data rate or modulation mode is preset between the optical line terminal and the digital optical network unit. That is, the optical line terminal side also sends the preamble by using the preset data rate or modulation method, so that the digital optical network unit can demodulate the preamble by using a correct demodulation method.

According to the first aspect, the second aspect, any implementation manner of the first aspect, or any implementation manner of the second aspect, in another possible implementation manner of the data packet processing method, the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform a destination device that the optical line terminal is to change a modulation method used for sending the preamble. The second field may be a newly added field in the preamble. The second field may also be a newly added field in the ethernet packet. Alternatively, the second field may also multiplex existing fields in the preamble or in the ethernet packet.

The second field specifically indicates a modulation mode adopted by the changed preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

In this implementation manner, the optical line terminal can flexibly and dynamically change the modulation mode used for sending the preamble, and can improve the probability of correctly receiving the data packet by the optical network unit and improve the reliability of the system.

In a third aspect, an optical line terminal is provided, where the optical line terminal includes: a processor configured to generate a data packet, the data packet including a preamble and an Ethernet packet; a transceiver for transmitting the data packet; the preamble includes a first field, where the first field is used to indicate at least one of a data rate and a modulation scheme used by the olt to send the ethernet packet. The optical line terminal can send each data packet on the same waveband, each optical network unit can identify the preamble of each data packet, and determine the modulation mode of the Ethernet packet corresponding to the logical link identifier of the optical network unit according to the preamble, so that the Ethernet packet can be demodulated according to a correct demodulation mode. Therefore, when the PON system after upgrading has the optical network units with various modulation modes, the defects of overlarge complexity and overlarge insertion loss of optical components caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

In a fourth aspect, an optical network unit is provided, which includes: a transceiver, configured to receive a data packet, where the data packet includes a preamble and an ethernet packet, the preamble includes a logical link identifier and a first field, and the first field is used to indicate at least one of a data rate and a modulation scheme used by an olt to send the ethernet packet; the processor is used for analyzing the preamble to obtain the logical link identifier and a first field; the transceiver is further configured to demodulate the ethernet packet according to the data rate or modulation mode indicated by the first field when the logical link identifier matches the optical network unit; the processor is further configured to parse the demodulated ethernet packet. The optical line terminal can send each data packet on the same waveband, each optical network unit can identify the preamble of each data packet, and determine the modulation mode of the Ethernet packet corresponding to the logical link identifier of the optical network unit according to the preamble, so that the Ethernet packet can be demodulated according to a correct demodulation mode. Therefore, when the PON system after upgrading has the optical network units with various modulation modes, the defects of overlarge complexity and overlarge insertion loss of optical components caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

In a fifth aspect, a passive optical network system is provided, which includes: the optical line terminal according to the third aspect, and the optical network unit according to the fourth aspect.

In a further aspect of the present application, a computer-readable storage medium is provided, in which computer software instructions for the optical line terminal according to the third aspect are stored, and when the instructions are executed on a computer, the computer is caused to execute the method according to the above aspects.

In yet another aspect of the present application, a computer-readable storage medium is provided, in which computer software instructions for an optical network unit according to the fourth aspect are stored, and when the instructions are executed on a computer, the computer is caused to execute the method according to the above aspects.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the embodiments and the drawings used in the description of the prior art, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to these drawings without inventive labor.

Fig. 1 is a schematic diagram of a PON system according to an embodiment of the present invention;

FIG. 2 is an exemplary flow chart of a method of packet processing according to an embodiment of the invention;

FIG. 3 is a diagram illustrating an exemplary structure of a data packet according to an embodiment of the invention;

FIG. 4 is a diagram illustrating a preamble structure in the prior art;

FIG. 5 is a diagram illustrating an exemplary structure of a preamble according to an embodiment of the invention;

FIG. 6 is a diagram illustrating another exemplary structure of a preamble according to an embodiment of the invention;

figure 7 is a diagram illustrating an exemplary hardware configuration of an optical line terminal according to an embodiment of the present invention;

FIG. 8 is a diagram illustrating an exemplary hardware configuration of an ONU according to an embodiment of the present invention;

FIG. 9 is a diagram illustrating exemplary functional blocks of a communication device according to an embodiment of the present invention;

fig. 10 is a diagram illustrating another exemplary functional module of a communication device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme of the embodiment of the invention can be applied to various passive optical networks, such as: gigabit Passive Optical Network (GPON), Ethernet Passive Optical Network (EPON), ten Gigabit Passive Optical Network (XG-PON), Next Generation Passive Optical Network (NGPON), and the like.

Fig. 1 is a schematic diagram of an architecture of a PON system to which a packet processing method according to an embodiment of the present invention is applied, and as shown in fig. 1, the PON system 100 includes at least one OLT110, at least one ODN 120, and a plurality of ONUs 130. The OLT110 provides a network side interface for the PON system 100, the ONU130 provides a user side interface for the PON system 100, and the OLT110 and the ONU130 are connected to the ODN 120 respectively. If ONU130 directly provides the user port function, it is called Optical Network Terminal (ONT). For convenience of description, the ONU130 mentioned below refers to an ONT that can directly provide a user port function and an ONU that provides a user side interface. The ODN 120 is a network composed of optical fibers and passive optical splitting devices, and is used for connecting the OLT110 device and the ONU130 device, and for distributing or multiplexing data signals between the OLT110 and the ONU 130.

In the PON system 100, a direction from the OLT110 to the ONUs 130 is defined as a downstream direction, and a direction from the ONUs 130 to the OLT110 is defined as an upstream direction. In the downlink direction, the OLT110 sends downlink data to a plurality of ONUs 130 managed by the OLT110 in a Time Division Multiplexing (TDM) manner, and each ONU130 only receives data carrying its own identity. In the uplink direction, the ONUs 130 communicate with the OLT110 in a Time Division Multiple Access (TDMA) manner, and each ONU130 transmits uplink data according to the Time domain resource allocated to it by the OLT 110. With the above mechanism, the downstream optical signal transmitted by the OLT110 is a continuous optical signal, and the upstream optical signal transmitted by the ONU130 is a burst optical signal.

The PON system 100 may be a communication network system that does not require any active devices to implement data distribution between the OLT110 and the ONUs 130, for example, in a specific embodiment, data distribution between the OLT110 and the ONUs 130 may be implemented by passive optical devices (such as optical splitters) in the ODN 120. The PON system 100 may be a GPON system defined in ITU-T g.984 standard, an Ethernet Passive Optical Network (EPON) defined in IEEE 802.3ah standard, or a 10G EPON. Various passive optical network systems defined by the above standards fall within the scope of the present invention.

The OLT110 is typically located in a Central Office (CO), and may collectively manage at least one ONU130 and transmit data between the ONU130 and an upper network. Specifically, the OLT110 may act as an intermediary between the ONUs 130 and the upper Network, such as the internet, a Public Switched Telephone Network (PSTN), transmitting data received from the upper Network to the ONUs 130, and transmitting data received from the ONUs 130 to the upper Network. In one embodiment, the OLT110 may include a transmitter configured to transmit downstream continuous optical signals to the ONUs 130 and a receiver configured to receive upstream burst optical signals from the ONUs 130, wherein the downstream optical signals and the upstream optical signals may be transmitted through the ODN 120, but the embodiments of the invention are not limited thereto.

The ONUs 130 may be distributively located at customer-side locations (e.g., customer premises). The ONUs 130 are network devices for communicating with the OLT110 and users. The ONUs 130 may transmit data received from the OLT110 to a user and transmit data received from the user to the OLT 110.

The ODN 120 may be a data distribution network including optical fibers, optical couplers, optical splitters, or other devices. In one embodiment, the optical fiber, optical coupler, optical splitter, or other device may be a passive optical device. Taking an optical splitter as an example, the optical splitter may be connected to the OLT110 through a trunk fiber and connected to the plurality of ONUs 130 through a plurality of branch fibers, respectively, so as to implement point-to-multipoint connection between the OLT110 and the ONUs 130. Additionally, in other embodiments, the ODN 120 may also include one or more processing devices, such as optical amplifiers or Relay devices (Relay devices). In addition, the ODN 120 may specifically extend from the OLT110 to multiple ONUs 130, but may also be configured in any other point-to-multipoint structure, and the embodiment of the present invention is not limited thereto.

When the OLT110 and the ONU130 transmit data, the data is modulated by Non-Return-to-Zero (NRZ) code Modulation, 4-level Pulse Amplitude Modulation (PAM 4), 8-level Pulse Amplitude Modulation (PAM 8), or the like. Different data rates correspond to various levels of modulation schemes, for example, a data rate corresponding to an NRZ level modulation scheme is 25G, a data rate corresponding to a PAM4 level modulation scheme is 50G, and a data rate corresponding to a PAM8 level modulation scheme is 75G. The baud rates corresponding to the modulation modes of various levels are the same, for example, the baud rates corresponding to the modulation modes of NRZ, PAM4 and PAM8 are all 25G.

The ONU130 device may be an analog ONU device or a digital ONU device. The OLT110 device may be an analog OLT device or a digital OLT device. For the digital OLT110, when data is transmitted, multiple modulation schemes may be adopted, for example, the data transmitted by the OLT110 may simultaneously include NRZ modulated data, PAM4 modulated data, and PAM8 modulated data; similarly, when receiving data, a plurality of demodulation methods may be employed. For the analog OLT110, only one modulation scheme can be used to transmit data. Simulating the modulation mode of the OLT110 related to its hardware structure; similarly, only one demodulation method can be used for receiving data.

For the digital ONU130, it can receive data in multiple modulation schemes, and can demodulate data in various modulation schemes by using multiple demodulation schemes. For example, NRZ-modulated data is demodulated by an NRZ demodulation method, and PAM-4 demodulation is performed for PAM 4-modulated data. For the analog ONU130, there is only one demodulation mode, which is related to its specific hardware structure. The analog ONU includes a transceiver, which may include a transmitter, and the modulation mode of the analog ONU is the modulation mode of the transmitter. For example, if the transmitter is NRZ modulated, the modulation scheme of the analog ONU is NRZ.

The upgrading of the PON system can be understood as: the upgrade of the ONU130, for example, by updating hardware or software of the ONU130, enables the ONU130 to have a higher-level modulation scheme, so that the ONU130 can transmit data at a higher data rate, or has a higher-level demodulation scheme, so that the ONU130 can receive data at a higher data rate, or has both the higher-level modulation scheme and the higher-level demodulation scheme, so that the ONU130 can transmit data and receive data at a higher data rate. The upgrading of the PON system can also be understood as: the upgrading of the OLT110, for example, by updating hardware or software of the OLT110, enables the OLT110 to have a higher-level modulation scheme, so that the OLT110 can transmit data at a higher data rate, or a higher-level demodulation scheme, so that the OLT110 can receive data at a higher data rate, or both a higher-level modulation scheme and a higher-level demodulation scheme, so that the OLT110 can transmit data and receive data at a higher data rate.

When upgrading the PON system, generally, it is required that the ONU130 of the user without the upgrade requirement is not changed in hardware, and only the ONU130 of the user with the upgrade requirement (for example, a new ONU 130) is upgraded, so that the OLT110 can be upgraded. The upgraded PON system needs to be compatible with the un-upgraded ONU 130. In the upgraded PON system, the OLT110 may be an analog OLT110 or a digital OLT 110. The following embodiments are described by taking the OLT110 as a digital OLT. The ONUs 130 in the upgraded PON system may all be analog ONUs 130, may all be digital ONUs 130, or may include both analog ONUs 130 and digital ONUs 130.

In an embodiment, baud rates of all OLTs and ONUs in the PON system are the same, thereby ensuring clock synchronization. No matter the ONU130 is a digital ONU or an analog ONU, since the modulation method adopted when the OLT110 side transmits data is NRZ, PAM4, PAM8, or the like, the baud rate is guaranteed to be unchanged, and thus it can be guaranteed that all ONUs 130 in the upgraded PON system can maintain clock synchronization.

In the upgraded PON system, the OLT110 sends downstream data to each ONU130, and each ONU130 can receive all the downstream data. Since there may be ONUs 130 with different modulation levels in the upgraded PON system, data rates of downlink data corresponding to the ONUs 130 with different modulation levels are different, that is, the downlink data sent by the OLT110 has different data rates. Therefore, in order to enable each ONU130 to demodulate its own data in the downlink data according to a correct demodulation manner, a data packet processing method is proposed below, which aims to realize that an upgraded PON system can be compatible with an upgraded ONU and an un-upgraded ONU simultaneously without using a wavelength division multiplexing manner, that is, the PON system can be compatible with ONUs with different modulation levels simultaneously. The following describes in detail a packet processing method provided by an embodiment of the present invention with reference to the accompanying drawings, as shown in fig. 2, the method includes:

s200, the optical line terminal OLT generates a data packet. As shown in fig. 3, the data packet includes a preamble and an ethernet packet.

S210, the OLT sends the data packet to the ONU.

In the embodiment of the present invention, the ethernet packet may carry a Multi-Point Control Protocol (MPCP) message or may also carry data information. Specifically, as shown in fig. 3, the ethernet packet includes a destination address field, a source address field, a type/length field, and the remaining fields. The type/length field is used to indicate the type carried by the ethernet packet, and when the type indicated by the type field is data, the remaining fields include specific data information. When the type indicated by the type field is an MPCP message, the remaining fields may include a distinguishing frame type field, a timestamp field, a function field, a check field, and the like.

The preamble includes a first field, and the first field is used for indicating at least one of a data rate and a modulation scheme used by the olt to send the ethernet packet. The preamble may further include a synchronization field, a frame delimiter field, a Logical Link Identifier (LLID) field, a check field, and the like.

The first field may be a newly added field. The existing preamble is 8 bytes (as shown in fig. 4), and the first field can be added by adding bytes. For example, the first field may be represented by adding 2 bytes to the existing preamble. The position of the newly added byte in the preamble may be set according to actual needs, for example, the newly added byte may be located after the byte where the synchronization field in the preamble is located, or may be located after the byte where the frame delimiter field in the preamble is located, or may be located after the byte where the LLID field in the preamble is located, or may be located after the last byte in the preamble.

Or, the bytes of the existing field in the preamble may be reallocated, the number of bytes occupied by the existing field in the preamble may be reduced, and the first field may be represented by the saved bytes. For example, bytes 1, 2, 4 and 5 in fig. 4 are sync fields, byte 3 is a frame delimiter field, bytes 6 and 7 are LLID fields, and byte 8 is a check byte. By reallocating the sync field (as shown in fig. 5), bytes 1, 2, and 4 are taken as the sync field and byte 5 is taken as the first field. Therefore, the byte number of the preamble is not increased, and the structure of the existing preamble can be changed as little as possible. Furthermore, it is also possible to use only the 1 st, 2 nd and 5 th bytes as the sync field and the 4 th byte as the first field; alternatively, only the 1 st and 2 nd bytes may be used as the sync field, and the 4 th and 5 th bytes may be used as the first field. It should be understood that other fields in the preamble may also be used as the first field, and the above is merely an example.

Alternatively, the first field may also multiplex an existing field in the preamble. For example, the first field may multiplex the synchronization field in the preamble. The synchronization field may be used not only for synchronization but also for indicating the data rate or modulation scheme used by the OLT to send the ethernet packet. Specifically, at least two kinds of synchronization fields may be defined, and each kind of synchronization field corresponds to one modulation scheme. Since the modulation schemes correspond to the data rates one to one, each sync field corresponds to one data rate. A sync field may be defined for each modulation scheme. For example, assuming that there are three modulation schemes, i.e., NRZ, PAM4, and PAM8, in the upgraded PON system, 3 kinds of sync fields, i.e., sync field a, sync field B, and sync field C, may be defined, where the sync field a is used to indicate the modulation scheme NRZ, the sync field B is used to indicate the modulation scheme PAM4, and the sync field C is used to indicate the modulation scheme PAM 8. The ONU receives the data packet containing the synchronization field A, can synchronize and determines that the modulation mode adopted by the Ethernet packet in the data packet is NRZ according to the synchronization field A; if the ONU receives the data packet containing the synchronization field B, the data packet can be synchronized, and the modulation mode adopted by the Ethernet packet in the data packet is determined to be PAM4 according to the synchronization field B; if the ONU receives the data packet containing the synchronization field C, synchronization is performed, and the modulation mode adopted by the ethernet packet in the data packet is determined to be PAM8 according to the synchronization field C.

For example, the modulation scheme corresponding to the 25G data rate is NRZ, the modulation scheme corresponding to the 50G data rate is PAM4, and the modulation scheme corresponding to the 75G data rate is PAM 8. Therefore, the first field may indicate only the data rate, only the modulation scheme, or both the data rate and the modulation scheme (for example, the first field is divided into two parts, one part indicates the data rate and the other part indicates the modulation scheme). For example, when the data rate is 25G, the first field may indicate only the data rate of 25G, or may indicate only the NRZ modulation scheme, or may indicate both the data rate of 25G and the NRZ modulation scheme.

When the OLT sends a data packet, the preamble and the ethernet packet may use the same modulation scheme or different modulation schemes.

Firstly, a modulation mode adopted by a sending preamble:

in the mode 1, the OLT transmits the preamble according to the lowest data rate or the lowest level modulation mode of each ONU which is communicated with the OLT.

For the analog ONU, data of the same level modulation scheme can be demodulated. For example, if the modulation scheme of the analog ONU is NRZ, the analog ONU can correctly demodulate data modulated by NRZ. In addition, the analog ONU may also demodulate data of a low-level modulation scheme, but the demodulated data needs to be converted to obtain correct original data. For example, if the modulation scheme of the analog ONU is PAM4, the analog ONU may demodulate data modulated by NRZ, but the demodulated data needs to be converted, for example, every 2 bits is converted into 1 bit according to a preset conversion rule, so that correct original data can be restored.

For the digital ONU, the data of various modulation modes can be demodulated.

If the PON system has both analog ONUs and digital ONUs, or all analog ONUs in the PON system, the preamble of each packet may be modulated according to the lowest data rate or the lowest level modulation method in the PON system in order to allow all ONUs in the PON system to recognize the preamble field of each packet. It can be understood that the lowest data rate or the lowest level modulation scheme in the PON system is the lowest data rate or the lowest level modulation scheme in each analog ONU in the PON system. For example, assuming that the ONU 131 in fig. 1 is a digital ONU, the ONU 132 is an analog ONU, the modulation schemes of the ONU 131 and the ONU 132 are NRZ, the ONU 133 is an analog ONU, and the modulation scheme of the ONU 133 is PAM4, the minimum data rate of each ONU in the PON system is 25G, and the minimum level modulation scheme is NRZ.

By the method, all the ONUs in the PON system can correctly demodulate the preamble, so that each ONU can judge whether the Ethernet packet corresponding to the preamble is sent to the ONU according to the preamble, and can know the demodulation mode of the Ethernet packet corresponding to the preamble according to the preamble (the demodulation mode corresponds to the modulation mode or the data rate indicated by the first field one by one), and each ONU can correctly demodulate the Ethernet packet sent to the ONU.

And in the mode 2, the OLT sends the preamble according to a preset data rate or a modulation mode.

For the data packet sent to the digital ONU, the OLT may send the preamble according to a preset data rate or a modulation mode, where the preset data rate or the modulation mode is predetermined between the OLT and the digital ONU. Therefore, the digital ONU can adopt a correct demodulation mode to demodulate the preamble.

In an embodiment, the method may be used in a PON system in which all ONUs are digital ONUs.

In another embodiment, this approach can also be used in PON systems that include both analog and digital ONUs. At this time, the preambles of all data packets sent to the digital ONU may be sent according to a preset data rate or modulation mode, and all data packets sent to the analog ONU may be sent according to the mode 1 described above.

Secondly, the modulation mode adopted for sending the Ethernet packet is as follows:

and the data rate and the modulation mode adopted for sending the Ethernet packet are the data rate and the modulation mode supported by the optical network unit corresponding to the logical link identification LLID.

In one example, one logical link identification corresponds to one ONU. If the ONU is an analog ONU, the modulation mode adopted by the Ethernet packet sent to the analog ONU is the modulation mode of the analog ONU itself. If the ONU is a digital ONU, the digital ONU can support multiple modulation schemes, and the OLT can select one of the modulation schemes as the modulation scheme used for sending the ethernet packet.

In another example, each logical link identification corresponds to at least two ONUs. I.e. at least two ONUs are assigned the same logical link identity. When each ONU corresponding to the logical link identifier is an analog ONU, the data rate used for sending the ethernet packet is the lowest data rate supportable in each ONU corresponding to the logical link identifier, and the modulation mode used for sending the ethernet packet is the lowest level modulation mode supportable in each ONU corresponding to the logical link identifier. When each ONU corresponding to the logical link identifier is a digital ONU, the data rate and the modulation mode supported by each digital ONU may be multiple, and the data rate and the modulation mode used for sending the ethernet packet may be one selected from the data rates and the modulation modes supported by each digital ONU corresponding to the logical link identifier. When each ONU corresponding to the logical link identifier includes both a digital ONU and an analog ONU, the data rate used for sending the ethernet packet is the lowest data rate supportable by each analog ONU corresponding to the logical link identifier, and the modulation scheme used for sending the ethernet packet is the lowest level modulation scheme supportable by each analog ONU corresponding to the logical link identifier.

And S220, the ONU receives the data packet.

In the embodiment of the present invention, after the ONU completes the optical-electrical conversion, the ONU is considered to complete the receiving operation. After the optical-electrical conversion of the data by the ONU, the processes such as clock synchronization, demodulation, and analysis can be continued.

S230, the ONU analyzes the preamble and extracts the logical link identification and the first field.

If the ONU is an analog ONU, S230 includes: and the ONU demodulates the preamble according to the data rate or the modulation mode of the ONU and analyzes the demodulated preamble. Specifically, the preamble is demodulated by a Limiting Amplifier (LA) in the analog ONU, the demodulated preamble is analyzed by a Media Access Control (MAC) chip in the analog ONU, and the analysis is performed according to the protocol (for example, each field in the bitstream (for example, each field in the preamble) is identified according to a frame format specified by the protocol).

For the analog ONU, if the level of the modulation scheme used by the OLT to send the preamble is equal to the level of the modulation scheme of the analog ONU itself, the ONU may demodulate the preamble according to the modulation scheme of the ONU itself.

It should be noted that, for an analog ONU, if the level of the modulation scheme used by the OLT to transmit the preamble is lower than the level of the modulation scheme of the analog ONU itself, the ONU needs to convert the demodulated preamble.

Specifically, the step of converting the demodulated preamble by the analog ONU includes: converting each bit group in the demodulated preamble into a bit sequence containing M bits; the number of bits of each bit group is the number of bits represented by each symbol period in the modulation scheme level corresponding to the ONU, and M is the number of bits represented by each symbol period in the modulation scheme level adopted for transmitting the preamble. The number of bits represented by each symbol period in the NRZ modulation scheme is 1, the number of bits represented by each symbol period in the PAM4 modulation scheme is 2, the number of bits represented by each symbol period in the PAM8 modulation scheme is 3, and the number of bits represented by each symbol period in the PAM16 modulation scheme is 3.

The level of the modulation scheme adopted for transmitting the preamble is NRZ, and the modulation level of the ONU is PAM 4. The rule for the ONU to convert the demodulated preamble can refer to table 1 below. Ideally, the bit group corresponding to the demodulated preamble has only two values, for example, only 00 and 11, or only 00 and 10. However, due to interference of noise, the bit group corresponding to the demodulated preamble may contain at least three values of 00, 01, 10, and 11, and in order to eliminate the interference, the bit groups 00 and 01 may be converted into 0, and the bit groups 10 and 11 may be converted into 1.

TABLE 1

Before conversion	After conversion
		00	0
01	0
		10	1
11	1

For example, a certain byte in the preamble transmitted by the OLT side is 01001101 (for the purpose of explaining the demodulation process, only a certain byte in the preamble is taken as an example for explanation, it is understood that the demodulation process of the entire preamble is similar to the demodulation process of the exemplified byte), and the modulation method adopted for transmitting the preamble is NRZ, bit 0 is transmitted as a low-level signal, and bit 1 is transmitted as a high-level signal. After receiving the preamble, the ONU at PAM4 modulation level demodulates the preamble according to PAM4 modulation scheme, and bit 0 transmitted in NRZ may be demodulated to 00 or 01, for example, and bit 0 bit 1 transmitted in NRZ may be demodulated to 10 or 11, for example. In the following, bit 0 demodulation is 00 and bit 1 demodulation is 11. The demodulated preamble is 0011000011110011, and according to table 1, the demodulated preamble can be converted to 01001101, so that the PAM4 modulation level ONU can correctly resolve the preamble.

If the ONU is a digital ONU, S230 includes: and the ONU demodulates the preamble according to a preset data rate or a modulation mode and analyzes the demodulated preamble. Specifically, the preamble is demodulated by a Digital Signal Processor (DSP) in the Digital ONU, and the electrical Signal is converted into a Digital Signal (e.g., a bit stream). The demodulated preamble is parsed by a Media Access Control (MAC) chip in the digital ONU, and the digital signal is parsed according to the protocol (e.g., each field in the bitstream (e.g., each field in the preamble) is identified according to a frame format specified by the protocol). The preset data rate or modulation mode is preset between the OLT and the digital ONU. That is, the OLT side also transmits the preamble using the preset data rate or modulation method, so that the digital ONU can demodulate the preamble using a correct demodulation method.

S240, when the logical link identification is matched with the ONU, the ONU demodulates the Ethernet packet according to the data rate or the modulation mode indicated by the first field and analyzes the demodulated Ethernet packet. For the specific details of the ONU demodulating the ethernet packet, reference may be made to the description of the ONU demodulating the preamble, and details are not described herein again. The specific details of the ONU analyzing and demodulating the ethernet packet may refer to the description of the ONU analyzing and demodulating the preamble, and are not described herein again.

And the ONU judges whether the logical link identifier in the preamble is the logical link identifier distributed by the OLT for the ONU, and when the logical link identifier in the preamble is the logical link identifier distributed by the OLT for the ONU, the logical link identifier is considered to be matched with the ONU. And when the logical link identification in the preamble is different from the logical link identification allocated by the OLT for the ONU, the logical link identification is considered not to be matched with the ONU.

For the analog ONU, if the modulation scheme level indicated by the first field is lower than the modulation scheme level of the ONU itself, the ONU needs to convert the demodulated ethernet packet. For details of the specific conversion, reference may be made to the above description of the preamble conversion, which is not described herein again.

When the logical link identifier does not match the ONU, the ONU may discard the ethernet packet in the packet in which the preamble is located, or discard the packet in which the preamble is located, or not process the ethernet packet in the packet in which the preamble is located.

In the embodiment of the present invention, the data packet is generated and sent by the OLT, and the data packet includes a preamble and an ethernet packet, the preamble includes a logical link identifier and a first field, and the first field is used to indicate at least one of a data rate and a modulation mode used by the OLT to send the ethernet packet. The ONU receives the data packet and analyzes the preamble to obtain a logical link identifier and a first field; and when the logical link identification is matched with the ONU, the ONU demodulates the Ethernet packet according to the data rate or the modulation mode indicated by the first field and analyzes the demodulated Ethernet packet. Because the first field in the preamble can indicate at least one of the data rate and the modulation mode adopted by the OLT to send the Ethernet packet, all the ONUs can demodulate the Ethernet packet with the destination address of the ONU according to the modulation mode indicated by the first field, and further, the condition that the OLT must send downlink data to the ONUs with different modulation levels in a wavelength division multiplexing mode is avoided, so that the OLT can send data packets to the ONUs with different modulation levels on the same wavelength channel, and therefore, when the ONUs with multiple modulation modes exist in the upgraded PON system, the defects of overlarge complexity and overlarge insertion loss of optical components caused by the adoption of the wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

Further, based on the above embodiment, the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform the ONU that the OLT will change the modulation scheme used for sending the preamble. Alternatively, the second field may also be used to inform the ONU that the OLT will change the data rate at which the preamble is sent. Since the data rate and the modulation scheme are in one-to-one correspondence, notifying the modified modulation scheme is equivalent to notifying the modified data rate, and vice versa.

In an embodiment, assuming that the OLT sends the packet including the second field to the ONU1, the OLT may start to change the modulation scheme for the next packet sent to the ONU1, or may start to change the modulation scheme for the packet sent to the ONU1 after a predetermined number of packets are separated, and the predetermined number of the separated packets may be predefined between the OLT and the ONU.

The second field may be a newly added field. In one example, the second field may be a field added to the preamble. For example, the existing preamble is 8 bytes, and the second field can be added by adding bytes. The position of the newly added second field can be set according to actual needs, and the second field may be adjacent to the first field or not. Or, the bytes of the existing field in the preamble can be redistributed, the number of bytes occupied by the original field in the preamble is reduced, and the saved bytes are used for representing the second field. In another example, the second field may also be a newly added field in the ethernet packet. The ethernet packet may now carry MPCP messages. Specifically, how to add new ethernet packets in the ethernet packet can refer to the related description of the new ethernet packet in the preamble, and will not be described herein again.

Alternatively, the second field may also multiplex existing fields in the preamble or in the ethernet packet. The details of the specific multiplexing can refer to the above description related to the multiplexing of the first field, and are not described herein again.

In one example, the second field specifically indicates a modulation scheme adopted for transmitting the preamble after the change. For example, the OLT transmits a packet using the PAM4 modulation scheme, and the packet includes the second field, and the modified modulation scheme indicated by the second field is NRZ.

In another example, the second field specifically indicates that the OLT is to change the modulation scheme or data rate used for transmitting the preamble, and may be a flag bit, for example, if the flag bit is 1, the change is indicated, and if the flag bit is 0, the no change is indicated. As shown in fig. 6, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the modified modulation scheme used for transmitting the preamble.

In one embodiment, the third field may be a newly added field. In another embodiment, the third field may also multiplex existing fields in the preamble or in the ethernet packet. For details, reference may be made to the above description related to the second field, which is not described herein again.

In one example, at least two of the first field, the second field, and the third field may multiplex the same byte. For example, the first 4 bits of the byte represent the first field and the last 4 bits represent the second field.

In this embodiment, the OLT may flexibly and dynamically change the modulation scheme used for sending the preamble, and may improve the probability that the ONU correctly receives the data packet and improve the reliability of the system.

Further, based on the above description, the following proposes a flow of ONU registration online:

1) the OLT issues an authorization message;

2) the ONU to be registered enters a pre-registration state after the clock is locked, and starts timing;

3) and if the ONU to be registered can correctly analyze the GATE frame in the authorization message, sending a registration request message to the OLT, allocating an LLID (logical link identifier) for the ONU to be registered by the OLT according to the registration request message, performing Dynamic Bandwidth Allocation (DBA) scheduling and the like, and finishing registration.

4) If the ONU to be registered fails to correctly analyze the GATE frame in the authorization message, the ONU is in a waiting modulus, the laser is turned off, and a registration request message cannot be sent to the OLT.

5) If the OLT does not receive the registration request message returned by the ONU after issuing the authorization message for a preset time interval, it may try to reduce the level of the modulation scheme used for sending the authorization message. For example, if the modulation scheme used by the OLT to issue the grant message in step 1) is PAM4, the modulation scheme may be reduced to NRZ to send the grant message to the ONU again in step 5). It will be appreciated that this step may be repeated. Until it is reduced to the lowest level of modulation, i.e. until it is reduced to the NRZ modulation.

6) If the ONU to be registered can correctly analyze the GATE frame in the authorization message reducing the modulation mode level, executing step 3); and if the ONU to be registered still cannot correctly analyze the GATE frame in the authorization message, continuing to be in a waiting mode until the timing duration of the ONU reaches the preset duration, sending a registration releasing instruction to the OLT by the ONU, and taking the ONU off line.

The present invention also provides an OLT110 as described in the various embodiments above. As shown in fig. 7, the OLT110 may include a processor 310, a memory 320, a transceiver 330, and a wavelength division multiplexer 340.

The processor 310 may be a general Central Processing Unit (CPU), a microprocessor, an application specific integrated circuit ASIC, or at least one integrated circuit, and is configured to execute related programs to implement the technical solution provided by the embodiment of the present invention. The processor 310 is also configured to perform the modulation and demodulation functions described above.

The Memory 320 may be a Read Only Memory (ROM), a static Memory device, a dynamic Memory device, or a Random Access Memory (RAM). The memory 320 may store an operating system and other application programs. When the technical solution provided by the embodiment of the present invention is implemented by software or firmware, a program code for implementing the technical solution provided by the embodiment of the present invention is stored in the memory 320 and executed by the processor 310.

The transceiver 330 may include an optical transmitter and/or an optical receiver. The optical transmitter may be used to transmit signals and the optical receiver may be used to receive signals. The light emitter may be implemented by a light emitting device such as a gas laser, a solid laser, a liquid laser, a semiconductor laser, a direct modulation laser, or the like. The optical receiver may be implemented by a photodetector, such as a photodetector or a photodiode (e.g., an avalanche diode), etc. The transceiver 330 may also include a digital-to-analog converter and an analog-to-digital converter. The transceiver 330 may also include the limiting amplifier described above.

The OLT110 may also include a Medium Access Control (MAC) for performing the above-described parsing functions. The MAC may exist independently of processor 310 or may be part of processor 310.

The wavelength division multiplexer 340 is connected to the transceiver 330 and acts as a multiplexer when the OLT110 transmits signals. When the OLT110 receives a signal, the wavelength division multiplexer acts as a demultiplexer. Wavelength division multiplexers may also be referred to as optical couplers.

Wherein the processor 310 is configured to generate a data packet, and the data packet includes a preamble and an ethernet packet; the preamble includes a first field, and the first field is used for indicating at least one of a data rate and a modulation scheme used by the olt to send the ethernet packet.

The transceiver 330 is used for transmitting the data packet.

As can be seen from the above embodiments, the OLT110 shown in fig. 7 performs steps S200 and S210 in the embodiment shown in fig. 2. Specifically, the processor 310 executes step S200. The transceiver 330 performs step S210. Further details of the steps performed by the processor 310 and the transceiver 330 can be described in relation to the embodiments of the packet processing method and the drawings, and are not repeated herein.

It is understood that the OLT110 described above may also include other components, which are not described in detail herein.

In the embodiment of the invention, the OLT can send each data packet on the same wave band, each ONU can identify the preamble of each data packet, and the modulation mode of the Ethernet packet corresponding to the logic link identification of the ONU is determined according to the preamble, so that the Ethernet packet can be demodulated according to a correct demodulation mode. Therefore, when the ONU with multiple modulation modes exists in the upgraded PON system, the defects of overlarge complexity and overlarge insertion loss of an optical component caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

The present invention further provides an ONU130 according to the above embodiments. As shown in fig. 8, the ONU130 comprises a processor 410, a memory 420, a transceiver 430, and a wavelength division multiplexer 440.

The processor 410 may be a general-purpose Central Processing Unit (CPU), a microprocessor, an application specific integrated circuit ASIC, or at least one integrated circuit, and is configured to execute related programs to implement the technical solution provided by the embodiment of the present invention. The processor 410 is also configured to perform the modulation and demodulation functions described above.

The Memory 420 may be a Read Only Memory (ROM), a static Memory device, a dynamic Memory device, or a Random Access Memory (RAM). The memory 420 may store an operating system and other application programs. When the technical solution provided by the embodiment of the present invention is implemented by software or firmware, a program code for implementing the technical solution provided by the embodiment of the present invention is stored in the memory 420 and executed by the processor 410.

The transceiver 430 may include an optical transmitter and/or an optical receiver. The optical transmitter may be used to transmit signals and the optical receiver may be used to receive signals. The light emitter may be implemented by a light emitting device such as a gas laser, a solid laser, a liquid laser, a semiconductor laser, a direct modulation laser, or the like. The optical receiver may be implemented by a photodetector, such as a photodetector or a photodiode (e.g., an avalanche diode), etc. The transceiver 430 may also include a digital-to-analog converter and an analog-to-digital converter. The transceiver 430 may also include the limiting amplifier described above.

The ONU130 may further include a Medium Access Control (MAC) for performing the above-mentioned parsing function. The MAC may exist independent of processor 410 or may be part of processor 410.

The wavelength division multiplexer 440 is connected to the transceiver 430 and acts as a multiplexer when the ONU130 transmits signals. When the ONU130 receives a signal, the wavelength division multiplexer functions as a demultiplexer. Wavelength division multiplexers may also be referred to as optical couplers.

Wherein the transceiver 430 is configured to receive the data packet;

the processor 410 is configured to parse the preamble to obtain the logical link identifier and the first field;

the transceiver 430 is further configured to demodulate the ethernet packet according to the data rate or modulation mode indicated by the first field when the logical link identifier matches the ONU;

the processor 410 is further configured to parse the demodulated ethernet packet.

As can be seen from the above embodiment, the ONU130 shown in fig. 8 performs steps S220, S230, and S240 in the embodiment shown in fig. 2. Specifically, the processor 410 performs the parsing steps in steps S230 and S240. The transceiver 430 performs the demodulation steps in steps S220 and S240. Further details of the steps performed by the processor 410 and the transceiver 430 may be described in relation to the embodiments of the packet processing method and the drawings, and are not repeated herein.

It is understood that the ONU130 described above may further include other devices, which are not described herein.

The present invention also provides a passive optical network system, which includes the optical line terminal OLT and the optical network units ONU described in the above embodiments. Reference may be made to the above embodiments, which are not described herein again.

The embodiment of the present invention further provides a data packet, and the specific structure and description of the data packet may refer to the foregoing embodiment, which is not described herein again.

The embodiment of the present invention further provides a communication apparatus 500, where the communication apparatus 500 may be an optical line terminal, or a module, a component, a circuit, or a device in the optical line terminal. As shown in fig. 9, the communication apparatus 500 includes:

a generating module 510, configured to generate a data packet, where the data packet includes a preamble and an ethernet packet;

a sending module 520, configured to send the data packet;

the preamble includes a first field, where the first field is used to indicate at least one of a data rate and a modulation scheme used by the sending module to send the ethernet packet.

Further, the preamble further includes a logical link identifier, and the data rate and the modulation mode used by the sending module to send the ethernet packet are the data rate and the modulation mode supported by the optical network unit corresponding to the logical link identifier.

Further, the sending module 520 sends the preamble according to the lowest data rate or the lowest level of the modulation scheme of each onu in communication with the communication apparatus; or, the sending module sends the preamble according to a preset data rate or a modulation mode.

Further, the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform the destination device that the transmission module will change the modulation method used for transmitting the preamble.

Further, the second field specifically indicates a modulation method adopted by the changed preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

As can be seen from the above embodiment, the communication device 500 performs the steps S200 and S210 in the embodiment shown in fig. 2. Specifically, the generating module 510 executes step S200, and the sending module 520 executes step S210. Further details of the communication device 500 when performing the above steps can be described in relation to various embodiments of the above data packet processing method and the accompanying drawings, and are not described herein again.

In this embodiment of the present invention, the communication device 500 may send each data packet on the same band, and each ONU may identify the preamble of each data packet, determine the modulation mode of the ethernet packet corresponding to its own logical link identifier according to the preamble, and further demodulate the ethernet packet according to the correct demodulation mode. Therefore, when the ONU with multiple modulation modes exists in the upgraded PON system, the defects of overlarge complexity and overlarge insertion loss of an optical component caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

The embodiment of the present invention further provides a communication apparatus 600, where the communication apparatus 600 may be an optical network unit, an optical network terminal, a module, a component, a circuit, or a device in the optical network unit or the optical network terminal. As shown in fig. 10, the communication apparatus 600 includes:

a receiving module 610, configured to receive a data packet, where the data packet includes a preamble and an ethernet packet, where the preamble includes a logical link identifier and a first field, and the first field is used to indicate at least one of a data rate and a modulation scheme used by an olt to send the ethernet packet;

a parsing module 620, configured to parse the preamble to obtain the logical link identifier and the first field;

a demodulation module 630, configured to demodulate the ethernet packet according to the data rate or modulation mode indicated by the first field when the logical link identifier matches the communication apparatus;

the parsing module 620 is further configured to parse the demodulated ethernet packet.

Further, the demodulation module 630 is further configured to demodulate the preamble according to its own data rate or modulation mode, and the analysis module 620 is specifically configured to analyze the demodulated preamble;

or, the demodulation module 630 is further configured to demodulate the preamble according to a preset data rate or a modulation mode, and the analysis module is specifically configured to analyze the demodulated preamble.

Further, the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform the communication device that the olt will change the modulation scheme used for sending the preamble.

As can be seen from the above embodiment, the communication apparatus performs steps S220, S230, and S240 in the embodiment shown in fig. 2. Specifically, the receiving module executes step S230; the demodulation module is used for executing the demodulation step in step S230 and the demodulation step in step S240; the parsing module is used for executing the parsing step in step S230 and the parsing step in step S240. More details of the communication device when executing the above steps may be described in relation to each embodiment of the data packet processing method and the accompanying drawings, and are not described herein again.

In the embodiment of the invention, the communication device can send each data packet on the same wave band, each ONU can identify the preamble of each data packet, and determine the modulation mode of the Ethernet packet corresponding to the logical link identifier of the ONU according to the preamble, so that the Ethernet packet can be demodulated according to a correct demodulation mode. Therefore, when the ONU with multiple modulation modes exists in the upgraded PON system, the defects of overlarge complexity and overlarge insertion loss of an optical component caused by adopting a wavelength division multiplexing mode can be avoided, and smooth upgrading is realized.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the above-described embodiments of the apparatus are merely illustrative, and for example, the above-described division of the units is only one type of division of logical functions, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of some interfaces, devices or units, and may be an electric or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit may be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as a separate product. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like, and may specifically be a processor in the computer device) to execute all or part of the steps of the above-described method according to the embodiments of the present invention. The storage medium may include: a U disk, a removable hard disk, a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or other various media capable of storing program codes.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A method for packet processing, the method comprising:

the optical line terminal generates a data packet, wherein the data packet comprises a preamble and an Ethernet packet;

the optical line terminal sends the data packet;

the preamble comprises a first field, and the first field is used for indicating at least one of a data rate and a modulation mode adopted by the optical line terminal for sending the Ethernet packet;

the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform a destination device that the optical line terminal will change a modulation scheme used for sending the preamble.

2. The method according to claim 1, wherein the preamble further includes a logical link identifier, and the data rate and the modulation scheme used for sending the ethernet packet are the data rate and the modulation scheme supported by the optical network unit corresponding to the logical link identifier.

3. The method according to claim 1 or 2, wherein the optical line terminal sends the preamble according to the lowest data rate or the lowest level of modulation scheme of each optical network unit communicating with the optical line terminal; or, the optical line terminal sends the preamble according to a preset data rate or a modulation mode.

4. The method of claim 1, wherein the second field specifically indicates a modified modulation scheme used for transmitting the preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

5. A method for packet processing, the method comprising:

an optical network unit receives a data packet, wherein the data packet comprises a preamble and an Ethernet packet, the preamble comprises a logical link identifier and a first field, and the first field is used for indicating at least one of a data rate and a modulation mode adopted by an optical line terminal for sending the Ethernet packet;

the optical network unit analyzes the preamble to obtain the logical link identifier and a first field;

when the logical link identification is matched with the optical network unit, the optical network unit demodulates the Ethernet packet according to the data rate or modulation mode indicated by the first field and analyzes the demodulated Ethernet packet;

the preamble further includes a second field, or the ethernet packet includes a second field, where the second field is used to inform the onu that the olt will change the modulation scheme used for sending the preamble.

6. The method of claim 5, wherein parsing the preamble by the ONU comprises: the optical network unit demodulates the preamble according to the data rate or the modulation mode of the optical network unit and analyzes the demodulated preamble; or, the optical network unit demodulates the preamble according to a preset data rate or a modulation mode, and analyzes the demodulated preamble.

7. The method of claim 5, wherein the second field specifically indicates a modified modulation scheme used for transmitting the preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

8. An optical line terminal, characterized in that the optical line terminal comprises:

a processor configured to generate a data packet, the data packet including a preamble and an Ethernet packet;

a transceiver for transmitting the data packet;

9. The olt of claim 8, wherein the preamble further includes a logical link id, and a data rate and a modulation scheme used by the transceiver to send the ethernet packet are supported by the onu corresponding to the logical link id.

10. The olt of claim 8 or 9, wherein the transceiver sends the preamble according to a lowest data rate or a lowest level of modulation scheme of each onu in communication with the olt; or, the transceiver transmits the preamble according to a preset data rate or a modulation mode.

11. The olt of claim 8, wherein the second field specifically indicates a modified modulation scheme used to send the preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

12. An optical network unit, comprising:

a transceiver, configured to receive a data packet, where the data packet includes a preamble and an ethernet packet, the preamble includes a logical link identifier and a first field, and the first field is used to indicate at least one of a data rate and a modulation scheme used by an olt to send the ethernet packet;

the processor is used for analyzing the preamble to obtain the logical link identifier and a first field;

the transceiver is further configured to demodulate the ethernet packet according to the data rate or modulation mode indicated by the first field when the logical link identifier matches the optical network unit;

the processor is further configured to parse the demodulated ethernet packet;

13. The onu of claim 12, wherein the transceiver is further configured to demodulate the preamble according to its own data rate or modulation scheme, and wherein the processor is further configured to parse the demodulated preamble; or, the transceiver is further configured to demodulate the preamble according to a preset data rate or a modulation method, and the processor is further configured to analyze the demodulated preamble.

14. The onu of claim 12, wherein the second field specifically indicates the modified modulation scheme used for transmitting the preamble; or, the preamble or the ethernet packet further includes a third field, where the third field is used to indicate the changed modulation scheme used for transmitting the preamble.

15. A passive optical network system comprising an optical line terminal according to any of the preceding claims 8 to 11 and an optical network unit according to any of the preceding claims 12 to 14.