Method for collecting data at ONU of optical distribution network

Abstract

A method for collecting data, the method comprising: at an ONU of an optical distribution network: receiving downstream data packets in a downstream frame, each downstream data packet comprising a Layer 2 header comprising at least an upstream transmission opportunity and a corresponding allocation ID, where each allocation ID identifies a T-CONT of the ONU of the optical distribution network, the upstream transmission opportunity defines an upstream bandwidth allocation for the T-CONT of the ONU; extracting an upstream transmission opportunity and at least a portion of its corresponding allocation ID from the Layer 2 header; and collecting at least a portion of the upstream transmission opportunities and the corresponding allocation IDs for transmission as a Layer 3 output payload.

Description

Technical Field

[0001] The present disclosure relates to apparatus and methods for collecting data in downstream frames at an ONU of an optical distribution network.

[0002] In particular, the present disclosure relates to apparatus and methods for monitoring granted bandwidth allocations in an optical distribution network.

[0003] definition

[0004] In order to better understand the context of the present invention, several definitions in the ITU-T G.984.4 specification are listed below. In the present disclosure, the following definitions apply to any passive optical network, including but not limited to a gigabit-capable passive optical network.

[0005] Bandwidth Allocation: An upstream transmission opportunity granted by an Optical Line Terminal (OLT) to a designated service-bearing entity (also known as a T-CONT) within an Optical Network Unit (ONU) for the duration of a specified time interval.

[0006] Dynamic Bandwidth Allocation (DBA): The process by which an optical line terminal (OLT) allocates upstream passive optical network (PON) capacity among service-bearing entities within an optical network unit (ONU) based on dynamic indications of the activity status of those service-bearing entities and their configured service contracts.

[0007] Gigabit-capable passive optical network (G-PON): A variant of passive optical network (PON) access technology that supports transmission rates exceeding 1 Gbit / s and is based on the G.984 series of ITU-T recommendations.

[0008] G-PON transmission convergence (GTC) layer: A protocol layer of the G-PON protocol family located between the physical medium dependent (PMD) layer and the G-PON client. The G-PON transmission convergence (GTC) layer includes the GTC framing sublayer and the GTC adaptation sublayer.

[0009] GTC Adaptation Sublayer: A sublayer of the Gigabit-capable Passive Optical Network (G-PON) transport convergence layer that supports the functions of user data segmentation and desegmentation, Gigabit-capable Passive Optical Network Encapsulation Method (GEM) encapsulation, GEM frame delineation, and GEM port ID filtering.

[0010] GTC Framing Sublayer: A sublayer of the Gigabit-capable Passive Optical Network (G-PON) transport convergence layer that supports the functions of G-PON transport convergence (GTC) frame / burst encapsulation and delineation, embedded operations, administration and maintenance (OAM) processing, and allocation identifier (Alloc-ID) filtering.

[0011] Optical Access Network (OAN): A group of access links that share the same network-side interface and are supported by an optical access transmission system. An OAN may include multiple optical distribution networks (ODNs) connected to the same optical line terminal (OLT).

[0012] Optical Distribution Network (ODN): In the context of a Passive Optical Network (PON), a tree of optical fibers in an access network supplemented by power or wavelength splitters, filters, or other passive optical devices.

[0013] Optical Line Terminal (OLT): A device that terminates the common (root) endpoint of an optical distribution network (ODN), implements the passive optical network (PON) protocol (such as that defined by [ITU-T G.984.1]), and adapts PON protocol data units (PDUs) for uplink communications over the provider service interface. The Optical Line Terminal (OLT) provides management and maintenance functions for the subtended ODN and Optical Network Units (ONUs).

[0014] Optical Network Terminal (ONT): A single subscriber device that terminates any distributed (leaf) endpoint of an optical distribution network (ODN), implements the Passive Optical Network (PON) protocol, and adapts the PON protocol data unit (PDU) to the subscriber service interface. An ONT is a special case of an Optical Network Unit (ONU).

[0015] Optical Network Unit (ONU): A generic term for a device that terminates any distributed (leaf) endpoint of an optical distribution network (ODN), implements the Passive Optical Network (PON) protocol, and adapts PON protocol data units (PDUs) to subscriber service interfaces. In some contexts, ONU means multi-subscriber equipment.

[0016] Physical layer OAM (PLOAM): A message-based operations and management channel between the optical line terminal (OLT) and the optical network unit (ONU) that supports PON TC layer management functions, including ONU activation, ONU management and control channel (OMCC) establishment, encryption configuration, key management, and alarm signaling.

[0017] PDU: Protocol Data Unit

[0018] GEM: A Gigabit-Capable Passive Optical Network Packaging Method

[0019] GTC: Gigabit-capable passive optical network transmission convergence

[0020] OAM: Operations, Administration, and Maintenance

[0021] PLOAM: Physical layer OAM operations, administration and maintenance. Background Art

[0022] Passive Optical Network (PON) is a fiber-optic telecommunications technology used to provide broadband network access to end customers.

[0023] Its architecture implements a point-to-multipoint topology, where a single optical fiber serves multiple endpoints by dividing the fiber bandwidth between the endpoints using unpowered (passive) fiber splitters.

[0024] In the downstream direction, the service multiplexing function is centralized. The OLT uses the port ID as a key to multiplex frames onto the transmission medium to identify frames belonging to different downstream logical connections. Each ONU filters downstream frames based on their port IDs and processes only frames belonging to that ONU.

[0025] In the upstream direction, the service multiplexing function is distributed. The OLT grants upstream transmission opportunities or upstream bandwidth allocations to the service bearer entities in the opposite ONU. The service bearer entity of the ONU, which is the recipient of the upstream bandwidth allocation, is identified by its allocation ID (Alloc-ID). Bandwidth allocations to different Alloc-IDs are multiplexed in time as specified in the bandwidth map sent downstream by the OLT. Within each bandwidth allocation, the ONU uses the port ID as a multiplexing key to identify frames belonging to different upstream logical connections.

[0026] In other words, due to the topology of PON, the transmission modes for downstream (i.e., from OLT to ONU) and upstream (i.e., from ONU to OLT) are different. For downstream transmission, OLT broadcasts optical signals to all ONUs in continuous mode, that is, the downstream channel always has optical data signals. However, in the upstream channel, ONU cannot send optical data signals in CM. Using continuous mode will cause all signals sent from ONU to converge (with attenuation) into one optical fiber through a power splitter (used as a power coupler) and overlap. In order to solve this problem, burst mode (BM) is adopted for the upstream channel. A given ONU only sends optical packets when it is assigned a time slot and it needs to send, and all ONUs share the upstream channel in time division multiplexing (TDM) mode.

[0027] The OLT is responsible for dynamically calculating time slots and allocating them to different Alloc-IDs (transmission containers for data, several for each ONU) of the ONUs on the PON.

[0028] The OLT sends the time slots in a structure called a "bandwidth map / map" (BWmap).

[0029] The bandwidth map is embedded in the header of the downstream frame at the transport convergence layer.

[0030] Each ONU parses the entire header and looks up its Alloc-ID, and thus knows when to send data in the correct time slot.

[0031] During development of a new board, especially when utilizing new technologies, a large part of the bring-up and subsequent debug process involves checking the values ​​of these headers.

[0032] Furthermore, bandwidth maps and their generation define the behavior of the PON in all scenarios: reactivity to surges in upstream traffic, fairness during congestion, ranging, etc. Being able to study them in real time in dynamic scenarios and develop appropriate algorithms is a key enabler to bring more value to the OLT.

[0033] However, it is still difficult to directly and easily access bandwidth maps.

[0034] Several issues remain to be addressed:

[0035] - To debug new technologies (e.g. 25G), there is simply no dedicated equipment to read these headers available. Therefore, currently, the transport layer of new fiber technologies is built “in the dark” by observing the effects and reverse engineering the values ​​that produce them rather than just reading the values.

[0036] - In any case, the known equipment for the new technology is very expensive and difficult to obtain in large quantities.

[0037] - Known devices for current technology (particularly GPON and XGSPOON) are available but very specialized and not very scalable to obtain direct images or retransmissions of broadband mapping. In practice, known devices for current technology use on-board processing to record header values ​​and present a summary to the user via a graphical interface. The amount of headers that can be captured is defined by the device. However, this presentation is not achieved continuously (i.e., in real time) and the amount of headers that can be captured is limited.

[0038] Therefore, there is a need for an apparatus and method that can directly and easily access bandwidth mapping. Summary of the invention

[0039] An apparatus and method for collecting data packets in downstream frames at an ONU of an optical distribution network are disclosed.

[0040] In some embodiments, the present disclosure provides a method for collecting data, the method comprising: at an ONU of an optical distribution network:

[0041] receiving a downstream data packet in a downstream frame,

[0042] Each downstream data packet comprises a layer 2 header including at least an upstream transmission opportunity and a corresponding allocation identifier (Alloc-ID),

[0043] Wherein, each allocation ID identifies a T-CONT of an ONU of the optical distribution network,

[0044] Wherein, the upstream transmission opportunity defines the upstream bandwidth allocation for the T-CONT of the ONU;

[0045] extracting at least a portion of the upstream transmission opportunity and its corresponding allocation ID from the layer 2 header; and

[0046] At least a portion of the upstream transmission opportunities and corresponding allocation IDs are collected for transmission as a layer 3 output payload.

[0047] Due to these features, the method enables the collection of upstream transmission opportunities. This collection can in turn be used to analyze bandwidth allocation in a cheaper and easier way without requiring any additional equipment.

[0048] Another way of understanding it is that the method allows duplication at one ONU of the ODN of upstream transmission opportunities granted by the OLT for all ONUs of the ODN.

[0049] An upstream bandwidth allocation is a certain time period during which an ONU - identified by its Alloc-ID - can send data in the upstream direction of the optical distribution network.

[0050] The method may also include one or more of the following features.

[0051] In an embodiment, the method is implemented for each downstream frame at a nominal bit rate comprised between 120 μs and 130 μs.

[0052] Due to this feature, the collection and hence the analysis is done on-board or in real-time. As a result, issues can be detected and resolved faster.

[0053] In an embodiment, the upstream transmission opportunity includes upstream bandwidth management information and / or dynamic bandwidth allocation.

[0054] In an embodiment, the method further comprises the step of sending the layer 3 output payload to a user output port of the ONU for further processing, for example by a computer coupled to the ONU.

[0055] In an embodiment, the layer 3 output payload is an Ethernet packet payload.

[0056] Typically, Ethernet packets are in a standard encapsulation format, so upstream transmission opportunities can be sent as any payload encapsulated in this standard format.

[0057] In an embodiment, the optical distribution network is a G-PON, such as XGS-PON, and layer 2 is a transmission convergence layer.

[0058] In an embodiment, Layer 2 is a transmission convergence layer comprising three sub-layers:

[0059] - Service Adaptation Sublayer,

[0060] - Framing sublayer,

[0061] - Physical Adaptation Sublayer;

[0062] And the received layer 2 header is part of the framing sublayer.

[0063] In an embodiment, the method further comprises determining that the allocation ID included in the layer 2 header is an active allocation ID, and sending the upstream transmission opportunity as a layer 3 output payload to an OLT of the optical distribution network.

[0064] Due to these features, transmission opportunities can be collected more easily because they are in a frame comprising the same, unique and dedicated header relative to the activation allocation ID.Thus, the golden ONU mode can be remotely activated by receiving the activation allocation ID.

[0065] In an embodiment, the method comprises the step of storing the layer 3 output payload in a memory of the ONU.

[0066] In an embodiment, the method further comprises:

[0067] - running a checking routine on the collected upstream transmission opportunities, wherein the checking routine comprises at least searching for mathematical errors in the collected upstream transmission opportunities.

[0068] In fact, since the received upstream transmission opportunities can be collected as useful data, they can then be processed. A useful process is to observe the bandwidth map sent by the OLT to the ONUs of the network. This analysis can be done in real time or with periodic updates. In turn, the bandwidth map can be analyzed and problems in the OLT can be detected.

[0069] In an embodiment, the optical distribution network is part of a mobile network, wherein the upstream transmission opportunity defines a target bandwidth allocated to the mobile antenna at a certain point in time, and the method further comprises:

[0070] - Comparing the target bandwidth allocated to the mobile antenna with the bandwidth required by the mobile antenna at that point in time.

[0071] In an embodiment, the method further comprises:

[0072] - encapsulate the Layer 3 output payload as a payload in an upstream packet, and

[0073] - Sending upstream packets in the upstream direction through the optical distribution network to the Optical Line Terminal (OLT) for inspection of the layer 3 output payload at the OLT.

[0074] In practice, processing of the extracted and collected upstream transmission opportunities can be done at the OLT level or higher. The OLT has better computing power, so a more advanced inspection of the collected upstream transmission opportunities can be achieved. Statistics about the bandwidth mapping can be recorded and used for monitoring.

[0075] In an embodiment, the method further comprises the step of sending the layer 3 output payload to a user output port of the ONU for further processing, for example by a computer coupled to the ONU.

[0076] In some embodiments, the present disclosure provides an apparatus comprising means for performing the following operations:

[0077] - receiving downstream data packets in downstream frames,

[0078] - each downstream data packet comprises a layer 2 header including at least an upstream transmission opportunity and a corresponding allocation ID (Alloc-ID),

[0079] Wherein, each allocation ID identifies a T-CONT of an ONU of the optical distribution network,

[0080] Wherein, the upstream transmission opportunity defines the upstream bandwidth allocation for the T-CONT of the ONU;

[0081] - extracting at least a portion of the upstream transmission opportunity and its corresponding allocation ID from the layer 2 header; and

[0082] - Collect at least a portion of upstream transmission opportunities and corresponding allocation IDs for transmission as layer 3 output payload.

[0083] In some example embodiments, the components in the apparatus further include:

[0084] - at least one processor; and

[0085] - at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the operation of the apparatus.

[0086] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0087] -Storing the layer 3 output payload in the network element's memory.

[0088] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0089] - Determine that the allocation ID included in the layer 2 header is an active allocation ID, and send the upstream transmission opportunity as a layer 3 output payload to the OLT.

[0090] Any other specific operations may be implemented by at least one processor.

[0091] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0092] - Sending the layer 3 output payload to a user output port of the network element for further processing, for example by a computer coupled to the network element.

[0093] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0094] - encapsulate the Layer 3 output payload as a payload in an upstream packet, and

[0095] - Sending the layer 3 output payload in the upstream direction through the optical distribution network to the Optical Line Terminal (OLT) for inspection at the OLT.

[0096] The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0097] - Real-time inspection of Layer 3 output payloads including upstream transmission opportunities, e.g., in the event of math errors, and / or

[0098] -Detect errors in upstream transmission opportunities.

[0099] In an embodiment, the optical distribution network is part of a mobile network, wherein an upstream transmission opportunity defines a target bandwidth allocated to a mobile antenna at a certain point in time, and the at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to:

[0100] - Comparing the target bandwidth allocated to the mobile antenna with the bandwidth required by the mobile antenna at that point in time.

[0101] In some example embodiments, the present disclosure also provides an apparatus comprising:

[0102] A first receiving circuit is configured to: receive a downstream data packet in a downstream frame,

[0103] Each downstream data packet includes a layer 2 header, which includes at least an upstream transmission opportunity and a corresponding allocation ID (Alloc-ID),

[0104] Wherein, each allocation ID identifies a T-CONT of an ONU of the optical distribution network,

[0105] Wherein, the upstream transmission opportunity defines the upstream bandwidth allocation for the T-CONT of the ONU;

[0106] A first extraction circuit configured to: extract at least a portion of an upstream transmission opportunity and its corresponding allocation ID from a layer 2 header; and

[0107] A first collection circuit is configured to collect at least a portion of upstream transmission opportunities and corresponding allocation IDs as a layer 3 output payload.

[0108] In some embodiments, the present disclosure further provides an apparatus comprising a first execution circuit configured to: periodically execute the above method with a time period included between 120 μs and 130 μs.

[0109] In some embodiments, the present disclosure further provides an apparatus comprising:

[0110] - a first storage circuit configured to store the layer 3 output payload in a memory of the apparatus.

[0111] In some embodiments, the present disclosure further provides an apparatus comprising:

[0112] - a first transmission circuit configured to: transmit the layer 3 output payload to a user output port of the apparatus for further processing, for example by a computer coupled to the apparatus.

[0113] In some embodiments, the present disclosure further provides an apparatus comprising:

[0114] - a first encapsulation circuit configured to: encapsulate the layer 3 output payload as a payload in an upstream packet, and

[0115] - A second transmitting circuit configured to transmit the upstream packets in an upstream direction through the optical distribution network to an optical line terminal (OLT) for inspection of a layer 3 output payload at the OLT.

[0116] In some embodiments, the optical distribution network is part of a mobile network, wherein an upstream transmission opportunity defines a target bandwidth allocated to a mobile antenna at a certain point in time, and the present disclosure further provides an apparatus comprising:

[0117] - a first comparison circuit, which is configured to compare the target bandwidth allocated to the mobile antenna with the bandwidth required by the mobile antenna at the time point. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] For a more complete understanding of example embodiments of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0119] Figure 1 A functional schematic diagram of a GPON network is shown;

[0120] Figure 2 shows a common functional view of the G-PON transmission convergence layer;

[0121] Figure 3 A functional schematic diagram showing bandwidth mapping granted by the OLT to the ONU 1;

[0122] Figure 4 A schematic diagram showing a downstream GTC frame structure;

[0123] Figure 5 and Figure 6 A schematic diagram showing the information encoded in a BWmap;

[0124] Figure 7 Shows multiple sub-layers of the transmission convergence layer in XGS-PON;

[0125] Figure 8 is a block diagram illustrating an apparatus 1200 operating in accordance with the example embodiments described above;

[0126] Fig. 9 Shows the relationship between ONU / ONT, T-CONT and GEM ports;

[0127] Fig.10 A sample / example model showing downstream business management;

[0128] Fig.11 A sample / example model showing upstream traffic management. DETAILED DESCRIPTION

[0129] Example embodiments of the present application are described in detail herein and illustrated by way of example in the accompanying drawings. It should be understood that although specific embodiments are discussed herein, it is not intended to limit the scope of the present invention to such embodiments. On the contrary, it should be understood that the embodiments discussed herein are for illustrative purposes, and modified and alternative embodiments may be implemented without departing from the scope of the present invention as defined in the claims. The order of the method steps is not limited to a specific embodiment, and the method steps may be performed in other possible orders. Similarly, the specific structural and functional details disclosed herein represent only the purpose of describing the embodiments. However, the invention described herein may be embodied in many alternative forms and should not be construed as being limited only to the embodiments set forth herein.

[0130] Generic architecture for passive optical networks

[0131] exist[ Figure 1 ] depicts a schematic view of a GPON network. A GPON network is a type of PON network. A Passive Optical Network (PON) is a level 1 fiber optic transmission principle used in fiber-to-the-home (FTTx) networks, characterized by a passive point-to-multipoint fiber architecture (several users share the same fiber and there are no active devices between the switch and the subscribers).

[0132] In the downstream direction, the OLT provides different ONUs via the ODN. In the upstream direction, the ONUs can send upstream information via the OLT.

[0133] OLT is the first aggregation point in the GPON access network. OLT terminates the GPON transmission convergence (GTC) layer on the user side and forwards Ethernet frames to the Ethernet layer on the network side. Figure 1 ] shows the termination points for the ONU / ONT scenario.

[0134] The U reference point represents the customer-facing interface of the ONU / ONT. When the ONT and RG equipment are combined into a single device, the U reference point may be within the ONU / ONT equipment.

[0135] The R / S reference point represents the ONT interface towards the OLT. The S / R reference point represents the GPON interface on the Optical Distribution Network (ODN) connecting the OLT. The S / R and R / S interfaces contain all the protocol elements required to allow communication between the OLT and one or more ONTs through the ODN.

[0136] The V reference point represents the network-facing interface of the OLT.

[0137] [ Fig. 9 ] describes the relationship between ONU / ONT, T-CONT and GEM port.

[0138] T-CONT: A service bearer object within an ONU / ONT that represents a group of logical connections and is considered a single entity for upstream bandwidth allocation purposes on a PON. In the upstream direction, it is used to carry service traffic. Each T-CONT corresponds to a service traffic of one bandwidth type. Each bandwidth type has its own QoS characteristics.

[0139] ALLOC_ID: Each T-CONT is uniquely identified by ALLOC_ID. ALLOC_ID ranges from 0 to 4095. It is allocated by the OLT, i.e., a T-CONT can be used by only one ONU / ONT per PON interface on the OLT.

[0140] GEM port: GPON encapsulation method (GEM) port is a virtual port, which is used to perform GEM encapsulation for sending frames between OLT and ONU / ONT. Each different service class (TC) of each UNI is assigned a different GEM port. Each T-CONT includes one or more GEM ports. Each GEM port carries a service business, that is, T-CONT type.

[0141] GEM Port ID: Each GEM port is uniquely identified by a Port ID. The Port ID ranges from 0 to 4095. It is assigned by the OLT, i.e., a GEM port can be used only by a single ONU / ONT per PON interface on the OLT.

[0142] Between the ONT and the OLT is the ODN, and Ethernet frames are carried on the ODN using GEM channels. GPON uses the GEM channel as part of its GTC layer. The GEM channel carries variable-length Ethernet frames. The GEM channel is identified by the GEM port ID. This identifier is assigned by the OLT when a new channel is created and is valid only during the entire life cycle of the channel. Each GPON interface for a given ONT can have several GEM ports. The GEM port ID is unique per GPON interface and represents a specific service or flow group between the OLT and the ONT.

[0143] There are 2 types of GEM channels:

[0144] Downstream GEM channels only - These channels are used to send downstream broadcast / multicast traffic from the OLT to all ONTs. The ONTs identify traffic intended for them based on the GEM port ID.

[0145] Bidirectional GEM channels - These channels are used for upstream and downstream traffic between the OLT and the ONTs. Frames are sent from the OLT into the GPON interface and forwarded only on the U interface of the ONT that has been assigned a GEM port.

[0146] GEM ports are used to differentiate service classes (TCs). A U interface may have several GEM ports associated with it that support different TCs. Thus, within a GPON interface, each GEM port carries one or more service flows associated with a specific TC.

[0147] On the U interface, the business is classified into VLANs with various Ethernet priorities based on the following items: physical port, VLAN ID, 802.1p bit, and / or DSCP. Once the business has been assigned VLAN and COS (802.1p) values, these two values ​​are used to select the upstream GEM port so that QoS can be applied to the stream carried by the GEM port. The GEM port always belongs to a single T-CONT. In the downstream direction, the ONT forwards the business received by the GEM port to the appropriate U interface.

[0148] Different VLAN architectures can be used. For example, 1:1 VLAN or N:1 VLAN can be used.

[0149] Time Division Multiplexing Architecture

[0150] For any passive optical network (eg, G-PON or XGS-PON), the principles of time division multiplexing (TDM) and time division multiple access (TDMA) apply.

[0151] As from Figure 1 As can be seen in Figure 1, GPON links connect OLT and ONT to transport Ethernet services. Note that GPON can also encapsulate ATM and TDM (E1, E3) services. The GTC adaptation sublayer maps Ethernet frames into GPON GEM frames. QoS mechanisms are required in GEM to support Ethernet QoS (i.e., 802.1p bits). To provide QoS, two mechanisms are used:

[0152] - Classify the business into business categories

[0153] - Forwards traffic classes to GEM ports and T-CONTs configured to emulate Ethernet QoS services

[0154] In the downstream direction of the PON, the service multiplexing function is centralized. The OLT multiplexes frames onto the transmission medium using the port ID as a key to identify frames belonging to different downstream logical connections. Each ONU filters downstream frames based on their port ID and processes only frames belonging to that ONU. Multicast ports can be used to carry frames to more than one ONU.

[0155] [ Fig.10 ] shows a sample / example model of downstream traffic management. In the downstream direction, T-CONT is not used. Traffic received from the V interface at the OLT is assigned to queues according to TC. In turn, it is sent to the PON interface in the downstream direction by using a scheduler. At the ONT, the traffic is again classified and placed into the appropriate queue for each U interface. The scheduler is used to send frames to the U interface.

[0156] In the upstream direction of the PON, the service multiplexing function is distributed. The OLT grants upstream transmission opportunities or upstream bandwidth allocations to the service bearer entities in the opposite ONU. The service bearer entity of the ONU, which is the recipient of the upstream bandwidth allocation, is identified by its allocation ID (Alloc-ID). Bandwidth allocations to different Alloc-IDs are multiplexed in time as specified in the bandwidth map sent downstream by the OLT. Within each bandwidth allocation, the ONU uses the port ID as a multiplexing key to identify frames belonging to different upstream logical connections.

[0157] [ Fig.11 ] shows a sample / example model for upstream traffic management. It shows 4 T-CONTs per PON interface, where each T-CONT represents a specific traffic class (TC). The classifier receives traffic from the U interface and maps it to queues as configured using the associated GEM port. If there is a second UNI interface on the same ONT, it will also perform classification and map traffic to TCs. As mentioned above, the GEM port must carry one or more T-CONTs. Depending on the TC, other upstream traffic from other ONTs is mapped to the other 4 T-CONTs.

[0158] At the OLT, each TC is mapped into a separate queue. T-CONTs from various ONTs sharing the same TC are mapped to the same queue and a scheduler is used in the queue towards the network facing port (ie, V interface).

[0159] Protocol Stack

[0160] A protocol stack or network stack is an implementation of a computer network protocol cluster or family. Some of these terms are used interchangeably, but strictly speaking, the cluster / family is the definition of the communication protocol and the stack is their software implementation.

[0161] In this document, since different layers include a physical medium dependent (PMD) layer and a transmission convergence layer (for a G-PON network, referred to as a G-PON transmission convergence layer), a protocol cluster / family is implemented.

[0162] In other words, layer 1 is the physical medium dependent (PMD) layer, and layer 2 is the transmission convergence layer (for a G-PON network, it is called the G-PON transmission convergence layer).

[0163] [ Figure 2 ] depicts a common functional view of the G-PON transmission convergence layer.

[0164] The GTC layer includes two sublayers, namely the GTC framing sublayer and the GTC adaptation sublayer. From another perspective, the GTC includes a control and management plane (C / M plane), which manages user traffic flows, security and OAM features, and a user data plane (U plane) that carries user traffic. In the GTC framing sublayer, the GEM part, the embedded OAM and the PLOAM part are identified according to the position on the GTC frame. For the purpose of local control, the embedded OAM is terminated at this sublayer because the information of the embedded OAM is directly included in the GTC frame header. The PLOAM information is processed at the PLOAM block located as the client of this sublayer. At the GTC adaptation sublayer, the service data unit (SDU) in the GEM part is converted / converted from a conventional GEM protocol data unit (PDU) to a conventional GEM protocol data unit (PDU).

[0165] In addition, these GEM PDUs carry OMCI channel data. OMCI channel data is identified at the adaptation sublayer and switched from / to the OMCI entity. Embedded OAM, PLOAM and OMCI are classified into the C / M plane. SDUs (except OMCI on GEM) are classified into the U plane.

[0166] The GTC framing sublayer has global visibility of all data sent, and the OLT GTC framing sublayer is a direct peer of all ONU GTC framing sublayers.

[0167] In addition, a DBA control block or a DBA function module is designated as a common function block in the GTC adaptation sublayer.

[0168] Downstream and upstream transmission

[0169] The OLT is required to send all pointers to any single ONU in ascending order of the start time.

[0170] Dynamic bandwidth allocation

[0171] Dynamic bandwidth allocation (DBA) in Gigabit-capable passive optical networks (G-PONs) is the process by which the optical line terminal (OLT) reallocates upstream transmission opportunities to service bearer entities within the optical network unit (ONU) based on dynamic indications of their activity status and their configured service contracts. Activity status indications can be explicit through buffer status reporting or implicit through the transmission of idle GEM frames in place of granted upstream transmission opportunities.

[0172] like[ Figure 3As shown in FIG. 1 , for each Alloc-ID logical buffer, the DBA function module of the OLT infers occupancy information by collecting in-band status reports or indirectly observing the upstream idle mode. Then, it derives the bandwidth allocation for each Alloc-ID based on these inputs, configurations, and fairness requirements, and then provides input to the OLT upstream bandwidth mapper, which is responsible for generating BWmaps at the frame rate. The BWmaps are transmitted to the ONU in-band together with the downstream traffic.

[0173] As an example, in [ Figure 4 A schematic diagram of the downstream GTC frame structure is shown in . For XGS-PON 10G, the frame duration is 125 μs and the length is 38880 words, which corresponds to a downstream data rate of 2.48832 Gbit / s. The PCBd length range depends on the number of allocation structures per frame.

[0174] However, the characteristics of the frame depend on the PON network. The frame can be different in the following PONs: GPON, XGS, 2.5 / XGS, 10G GHSP or 25G GHSP, etc.

[0175] Frame header and BWmap

[0176] The GTC system provides media access control for upstream services. In basic concept, the downstream frame indicates the permitted position of upstream services in the upstream GTC frame synchronized with the downstream GTC frame. Figure 5 ] shows the media access control concept in the GTC system.

[0177] The OLT sends pointers in the upstream bandwidth map (BWmap) field of the downstream physical control block (PCBd), and these pointers indicate the time when each ONU can start and end its upstream transmission. In this way, only one ONU can access the medium / medium at any time, and there is no competition in normal operation. The pointers are given in bytes, allowing the OLT to control the medium / medium with an effective static bandwidth granularity of 64kbit / s. However, some implementations of the OLT may choose to set the value of the pointer at a larger granularity (e.g., in words) and implement fine bandwidth control via dynamic scheduling.

[0178] The bandwidth map (BWmap) is a scalar array of 8-byte allocation structures. Each entry in the array represents a single bandwidth allocation for a specific Alloc-ID. The bandwidth map includes and defines one transmission opportunity per T-CONT of the ONU. Generally speaking, for PON efficiency, transmission opportunities for T-CONTs of the same ONU are grouped together as much as possible, but this is not mandatory.

[0179] The number of entries in the map is given in the PLend field. The format of each entry is given below and is given in [ Figure 6 ] is shown in ].

[0180] The OLT is required to send all pointers to any single ONU in ascending order of start time. It is recommended that all pointers be sent in ascending order of start time. The ONU shall be able to support up to eight allocation structures in any single BWmap, and optionally may support more allocation structures. In addition, the maximum BWmap size limit for an ONU shall be at least 256 allocation structures, with optional support for larger BWmaps.

[0181] The Allocation ID field contains a 12-bit number that indicates the recipient of the bandwidth allocation, i.e., a specific T-CONT within the ONU or an upstream OMCC. The 12-bit field is usually unstructured, but some conventions apply. First, the ONU is addressed directly using the lowest 254 Allocation ID values. During the ranging process, the first Alloc-ID provided to the ONU should be within this range. The first Alloc-ID provided to the ONU is called the default allocation ID. This Alloc-ID number is the same as the ONU-ID number (used in the PLOAM message). It is used to carry PLOAM and OMCI services and optional user services. If further.

[0182] The ONU requires Alloc-ID values, which should be obtained from values ​​above 255. In addition, Alloc-ID=254 is an Alloc-ID used to discover unknown ONUs, and Alloc-ID=255 is an unallocated Alloc-ID. This is used to indicate that no T-CONT can use the associated allocation structure.

[0183] The StartTime field contains a 16-bit number that indicates the start time of the allocation.

[0184] For GPON, this time is measured in bytes, starting from zero at the start of the upstream GTC frame. This limits the size of the upstream GTC frame to 65536 bytes. This is sufficient to handle upstream rates up to 4.194Gbit / s.

[0185] StartTime points to the start of valid data transmission and does not include the PLOu field. This makes the meaning of the pointer the same regardless of its position in a set of consecutive allocations for the same ONU. The physical layer overhead time is defined as the time required to include tolerance (guard time), receiver recovery, signal level recovery, timing recovery, delimiter, and three ONU specific fields, as defined in clause 8.2.2. The value used for the physical layer time varies based on the data rate in the upstream direction. Both the OLT and the ONU should be designed to accommodate the physical overhead time. The OLT has the responsibility to design the bandwidth mapping so that the physical layer overhead time is properly considered.

[0186] For GPON, BWmaps include StartTime and StopTime.

[0187] Note that StartTime must point to the time that occurs in the upstream GTC frame. Therefore, for all bit rates, the minimum value of StartTime can be zero. The maximum value depends on the bit rate, as follows: for an upstream bit rate of 1244.16 Mbit / s, the maximum StartTime value is 19438, and for 2488.32 Mbit / s it is 38878.

[0188] The StopTime field contains a 16-bit number that indicates the stop time of the allocation.

[0189] For GPON, this time is measured in bytes, starting from zero at the start of the upstream GTC frame. StopTime points to the last valid data byte associated with this allocation. Note that StopTime must indicate the time within the frame at which the allocation started. For XGS PON, BWmaps includes a StartTime and Duration similar to the StartTime of GPON, i.e., the length for the first T-CONT. Furthermore, the StartTime parameter can be omitted for other T-CONTs in the same ONU.

[0190] GTC Framing Sublayer

[0191] The GTC framing sublayer has the following three functions:

[0192] -1) Multiplexing and demultiplexing

[0193] -2) Header creation and decoding

[0194] -3) Internal routing function based on Alloc-ID

[0195] 1) Multiplexing and demultiplexing

[0196] The PLOAM and GTC payload parts are multiplexed into the downstream GTC frame as per the specified frame format. In the upstream direction, each part is extracted from the burst according to the BWmap corresponding to the upstream GTC frame to which the upstream burst belongs. See clause 8 for the downstream and upstream GTC frame format specifications.

[0197] 2) Header creation and decoding

[0198] Creates the GTC frame header and formats it in the downstream frame. Decodes the upstream burst header. Also, performs embedded OAM.

[0199] 3) Internal routing function based on Alloc-ID

[0200] Alloc-ID based routing is performed for data from / to the GEM TC adapter.

[0201] Summary of the Invention

[0202] PON systems are becoming more and more complex, and therefore bandwidth mapping is also becoming more and more complex.

[0203] For example, the number of T-CONTs and ONUs to be considered by the OLT is increasing, and efficient and high-performance reallocation of upstream transmission opportunities is becoming increasingly challenging.

[0204] For example:

[0205] - Some T-CONTs may take precedence over other T-CONTs,

[0206] -OLT can provide grants to the same T-CONT several times per frame,

[0207] -OLT can provide permission for T-CONT at a specific time.

[0208] As a result, optimizing bandwidth becomes increasingly difficult.

[0209] The ideas and advantages behind this invention are:

[0210] -Collect and stream the headers of downstream frames as standard data output on the ONU, which allows continuous capture and investigation / research using a computer. In addition, there is no limit on the amount of capture.

[0211] - Use the collected headers to investigate / study the instantaneous state of the PON (e.g., adding a new ONU, a sharp increase in traffic, a sudden decrease in traffic, burst traffic)

[0212] method

[0213] The following method is applicable to any passive optical network.

[0214] The example of a G-PON is described, but the invention is not limited to this particular passive optical network.

[0215] It is proposed to create a transport header sniffer using common equipment: ONU and computer equipment. A new conventional pipeline is added in the ONU chip to read, process (as it always does) the header in real time and then pass it to one of the ONU standard service outputs.

[0216] A computer plugged into the ONU reads the header as data, and in turn software on the computer can perform any number of processes on the collected and read data.

[0217] The processing is designed to be real-time, but any amount of post-processing can also be performed on the recording of the data.

[0218] The present disclosure proposes to add an option (e.g., software configuration option) on the ONU to set the ONU in a special operation mode called "golden ONU mode." The ONU suitable for operating in this special operation mode is called a "golden ONU."

[0219] In the golden ONU mode, the transport layer information (especially the framing sublayer information) is usually processed by the ONU.

[0220] Therefore, the ONU of the optical distribution network - hereinafter referred to as the golden ONU - receives downstream frames sent by the OLT to the multiple ONUs of the ODN.

[0221] The downstream frames include downstream data packets. Each downstream data packet includes a layer 2 header including at least an upstream transmission opportunity and a corresponding Alloc-ID.

[0222] Each corresponding Alloc-ID identifies a T-CONT of an ONU of an optical distribution network or a T-CONT of an ONU of a network segment of an optical distribution network.

[0223] Thus, the golden ONU receives all upstream transmission opportunities granted by the OLT to the different ONUs of the optical distribution network or segment.

[0224] The data packet may also include a layer 3 payload.

[0225] The upstream transmission opportunity includes upstream bandwidth management information and / or dynamic bandwidth allocation. In fact, the upstream opportunity granted by the OLT ("grant") is the result of dynamic bandwidth allocation and may include upstream bandwidth management information (e.g., a flag for requesting the T-CONT to indicate its queue length).

[0226] As an example, [ Figure 7] depicts multiple sublayers of the transmission convergence layer (GTC) in XGS-PON. In this particular PON network, the FS header includes an upstream transmission opportunity. Therefore, in this particular PON network, the layer 2 header including at least the upstream transmission opportunity and the corresponding ONU-ID is a FS header.

[0227] exist[ Figure 7 ], GTC is the entire layer including multiple sublayers. The framing (FS) sublayer is one of them. Therefore, the GTC frame includes the FS frame, and in particular, the FS header is the first part of the FS frame, and then it is also the last part of the GTC header.

[0228] For example, the upstream transmission opportunity includes the bandwidth map described above, and in particular the allocation ID field, the StartTime and the StopTime.

[0229] For example, the ONU-ID is the Alloc-ID of the PON network.

[0230] In the G-PON network, Layer 2 is the transmission convergence layer, which includes three sublayers:

[0231] - Service Adaptation Sublayer,

[0232] - Framing sublayer,

[0233] - Physical Adaptation Sublayer;

[0234] In turn, the received layer 2 header is processed by the layer 3 processing unit of the ONU as a layer 3 output payload. For example, they are processed by the Ethernet sublayer.

[0235] As a reminder, the PON assumes downstream distribution, and each ONU receives all downstream packets for all ONUs, but one ONU will only process packets for it, i.e., when it is identified in the layer 2 header of its own ONU-ID, it will further process the layer 2 header at the layer 2 level and process the payload. In addition, when the ONU cannot identify its own ONU-ID, it will not perform any processing on the layer 2 header. Here, according to the golden ONU mode, after the downstream packet has been processed, the layer 2 header is not discarded because the associated Alloc-ID is not its Alloc-ID, but the golden ONU extracts at least a part of the upstream transmission opportunity and its corresponding Alloc-ID from the layer 2 header.

[0236] In turn, the golden ONU collects the upstream transmission opportunities extracted from the layer 2 header and at least a portion of the extracted corresponding Alloc-IDs.

[0237] From this collection, the Golden ONU can then transmit the upstream transmission opportunity of the layer 2 header and its corresponding Alloc-ID to one of its output points via a dedicated route.

[0238] For example, it may be encapsulated as an Ethernet packet payload. In other words, the collected upstream transmission opportunities of the received layer 2 header may be sent as an Ethernet packet.

[0239] In other words, the Gold ONU sends the layer 3 output payload including the layer 2 header of the downstream frame to one of its output points through a dedicated routine.

[0240] For example, specialized routines may include:

[0241] - After processing the received layer 2 header, the golden ONU forwards the data packet including the layer 2 header of the upstream transmission opportunity to a specific processing unit of layer 3,

[0242] - the Golden ONU packages the data packets including the upstream transmission opportunity in the determined output format, for example as Ethernet packet payload, and

[0243] - The Golden ONU sends data packets including upstream transmission opportunities as normal output payload.

[0244] This causes the Gold ONU to output the layer 2 header information as a normal data stream (ie, as a layer 3 output payload).

[0245] For example, it allows sending the layer 3 output payload to the user output port of the ONU for further processing by, for example, a computer coupled to the ONU. In turn, the computer coupled to the ONU allows reading the bandwidth map granted by the OLT and in turn running a checking routine of the collected upstream transmission opportunities. For example, the checking routine may include searching for mathematical errors in the collected upstream transmission opportunities.

[0246] The ONU typically has an Ethernet port to connect to the user network, but it can also connect to devices according to other protocols besides the Ethernet protocol. This capability is one of the advantages of the method.

[0247] In an embodiment, the dedicated routine may include the step of storing packets corresponding to upstream transmission opportunities in a memory of the golden ONU.

[0248] In an embodiment, the golden operating mode may include:

[0249] - encapsulate the Layer 3 output payload as a payload in an upstream packet, and

[0250] - Sending upstream packets in the upstream direction through the optical distribution network to the Optical Line Terminal (OLT) for inspection of the layer 3 output payload at the OLT.

[0251] advantage

[0252] Connected devices

[0253] Due to the Golden ONU and the Golden Operation Mode, a device (eg, a computer) may also be connected to this standard data interface for real-time processing of the collected upstream transmission opportunities instead of discarding them.

[0254] In practice, the method implemented in the golden operating mode is implemented for each downstream frame, therefore assuming a nominal bit rate comprised between 120 and 130 μs.

[0255] Here are some other advantages of this approach:

[0256] - This allows capture during transition states of the PON and recording of bandwidth mapping during the entire event;

[0257] - This is a very common and relatively cheap device (it is just an ONU);

[0258] - The processing of data can be programmed very flexibly on a standard computer using any programming language.

[0259] One possible post-processing is to read the upstream transmission opportunities included in the layer 3 output payload (the bandwidth map generated by DBA and BWM) and check the upstream transmission opportunities in real time, for example, in case of mathematical errors.

[0260] Thanks to the invention, the behavior of the embedded code on the OLT (ie the bandwidth allocation code or the transmission protocol) can be analyzed and debugged when running on a circuit board.

[0261] For example, for any receiver device, you can:

[0262] - receiving at the ONU, within a determined amount of time, packets corresponding to upstream transmission opportunities collected in a determined number of downstream frames,

[0263] - read the bandwidth map of the ONU within a determined amount of time,

[0264] - Analyze the received bandwidth map.

[0265] Furthermore, errors in bandwidth mapping can be detected.

[0266] The upstream transmission opportunity may also be sent in the upstream direction through the PON to the OLT, for example to be checked at the OLT with respect to available data at the OLT.

[0267] When ONU is part of a mobile network deployment

[0268] In an embodiment, a PON network is used to transmit delay sensitive mobile data.

[0269] At one of the end-user ports of the ONU, a mobile station may be coupled to the port. The mobile station reports its required upstream mobile bandwidth. There are different ways in the prior art, for example, from the mobile station to the mobile core in the network (through the PON) according to the mobile protocol. The mobile core provides this bandwidth requirement to the OLT, which uses this information to calculate the appropriate "upstream transmission opportunity" for the end-user point of the ONU.

[0270] In other words, the upstream transmission opportunity defines in real time the target bandwidth allocated to the mobile antenna at a certain point in time for each frame.

[0271] In turn, the required upstream mobile bandwidth and upstream transmission opportunities may be checked / compared relative to each other.

[0272] Therefore, the target bandwidth allocated to the mobile antenna can be compared in real time with the bandwidth required by the mobile antenna at that point in time for each frame.

[0273] At the Gold ONU level

[0274] The extracted upstream transmission opportunities as described above may also be used directly at the golden ONU.

[0275] The Golden ONU can use them to read the bandwidth map granted by the OLT based on the extracted upstream transmission opportunities.

[0276] In turn, the golden ONU may run a check routine on the collected upstream transmission opportunities.

[0277] Preferably, the checking routine comprises at least searching for mathematical errors in the collected upstream transmission opportunities.

[0278] For example, basic or advanced checks, such as sanity checks, may be run on the collected upstream transmission opportunities.

[0279] Sanity checks may include checking that no grants overlap, or that no grants exceed the temporal boundaries of a frame.

[0280] Activate Alloc-ID

[0281] The golden operation mode implemented by the golden ONU may benefit from the fact that one of the received data packets comprises an activation Alloc-ID.

[0282] For example, a downstream data packet including an activation Alloc-ID may be created and sent by the OLT.

[0283] As a reminder, if the ONU-ID is the Alloc-ID of the PON network, they should be obtained from the values ​​above 255. In addition, Alloc-ID=254 is an Alloc-ID used to discover unknown ONUs, and Alloc-ID=255 is an unallocated Alloc-ID. This is used to indicate that no T-CONT can use the associated allocation structure.

[0284] Thus, for example, the active Alloc-ID may be set to 255. However, any Alloc-ID that does not exist on the PON may be used and all ONUs on the PON will simply ignore the entry as normal.

[0285] Furthermore, the golden operation mode may further include determining that the Alloc-ID included in the layer 2 header is an activation Alloc-ID, and sending the upstream transmission opportunity as a layer 3 output payload to the OLT.

[0286] By doing so, transmission opportunities can be collected more easily because they are in frames that include the same, unique and dedicated header relative to the activation Alloc-ID.

[0287] Here, the OLT receives the extracted upstream transmission opportunities, but any receiver device may be used. For example, the receiving device part of the optical distribution network may be used. Thus, the collected transmission opportunities are received better and faster.

[0288] Another potential use of ActivateAlloc-ID would be to stream the interval values ​​of the OLT relative to the BWmaps, i.e. any information or parameter relative to the BWmaps set by the OLT that changes at the frame rate and therefore cannot be recorded on the OLT itself. That is why by implementing this ActivateAlloc-ID mechanism, this information is published on the PON and in particular on the Golden ONU. The Golden ONU can thus observe and collect this information and in turn can do any processing / recording to capture the evolution of this internal value relative to the BWmaps.

[0289] Device

[0290] Figure 81 is a block diagram illustrating an apparatus 1200 operating according to the example embodiments described above (i.e., implementing the example embodiments). The apparatus 1200 may be, for example, an electronic device such as a chip, a chipset, an electronic device, or an access network controller. The apparatus 1200 includes a processor 1110 and a memory 1160. In other examples, the apparatus 1200 may include multiple processors.

[0291] exist Figure 8 In the example of the present invention, the processor 1110 is a control unit that is operably connected to read from and write to the memory 1160. The processor 1110 may also be configured to receive control signals received via the input interface and / or the processor 1110 may be configured to output control signals via the output interface. In an example embodiment, the processor 1110 may be configured to convert the received control signals into appropriate commands for controlling the functions of the device.

[0292] The memory 1160 stores computer program instructions 1120 which, when loaded into the processor 1110, control the operation of the apparatus 1200 according to the various embodiments described above. In other examples, the apparatus 1200 may include more than one memory 1160 or different kinds of storage devices.

[0293] The computer program instructions 1120 or a portion of such computer program instructions for implementing the exemplary embodiments of the present invention may be loaded onto the device 1200 by the manufacturer of the device 1200, the user of the device 1200, or the device 1200 itself based on a download program, or the instructions may be pushed to the device 1200 by an external device. The computer program instructions may arrive at the device 1200 via an electromagnetic carrier signal, or may be copied from a physical entity (such as a computer program product, a memory device or a recording medium, such as a compact disc (CD), a compact disc read-only memory (CDROM), a digital versatile disc (DVD) or a Blu-ray disc, a USB-KEY), or may be copied from the OLT.

[0294] According to an example embodiment, the apparatus 1200 comprises components, wherein the components include at least one processor 1110, at least one memory 1160 including computer program code 1120, the at least one memory 1160 and the computer program code 1120 being configured to, together with the at least one processor 1110, cause execution of the apparatus 1200.

[0295] Embodiments of the present invention may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside on an apparatus, a separate device, or multiple devices. If desired, portions of the software, application logic, and / or hardware may reside on an apparatus, portions of the software, application logic, and / or hardware may reside on separate devices, and portions of the software, application logic, and / or hardware may reside on multiple devices. In example embodiments, the application logic, software, or instruction set is stored on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any medium or component that can contain, store, communicate, propagate, or transmit instructions for execution by an instruction execution system, apparatus, or device (such as a computer, an example of which is Figure 8 Computer-readable media may include computer-readable storage media, which may be any medium or component that can contain or store instructions for use by or in conjunction with an instruction execution system, apparatus, or device (such as a computer).

[0296] If desired, the different functions discussed herein may be performed in different orders and / or simultaneously with each other. In addition, if desired, one or more functions described above may be optional or may be combined.

[0297] Although aspects of the invention are described in the independent claims, further aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with features of the independent claims, and not just the combinations explicitly described in the claims.

[0298] It will be obvious to a person skilled in the art that as technology advances, the inventive concept can be implemented in various ways.The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. A method for collecting data, the method comprising: At the ONU of the optical distribution network: receiving a downstream data packet in a downstream frame, Each downstream data packet comprises a layer 2 header including at least an upstream transmission opportunity and a corresponding allocation identifier, wherein each allocation identifier identifies a T-CONT of an ONU of the optical distribution network, wherein the upstream transmission opportunity defines an upstream bandwidth allocation for the T-CONT of the ONU; extracting at least a portion of the upstream transmission opportunity and its corresponding allocation identifier from the layer 2 header; and The at least a portion of the upstream transmission opportunities and the corresponding allocation identifiers are collected for transmission as a layer 3 output payload.

2. The method according to claim 1, wherein: The steps of claim 1 are performed periodically with a time period comprised between 120 μs and 130 μs.

3. The method according to any one of the preceding claims, further comprising the steps of: - sending the layer 3 output payload to a user output port of the ONU for further processing, for example by a computer coupled to the ONU.

4. A method according to any one of the preceding claims, wherein: The layer 3 output payload is an Ethernet packet payload.

5. A method according to any one of the preceding claims, wherein: The optical distribution network is a G-PON, for example, XGS-PON, and the layer 2 is a transmission convergence layer.

6. The method according to any one of the preceding claims, further comprising: An allocation identifier included in a layer 2 header is determined to be an active allocation identifier, and the upstream transmission opportunity is sent as a layer 3 output payload to an OLT of the optical distribution network.

7. The method according to any one of the preceding claims, further comprising the steps of: The layer 3 output payload is stored in a memory of the ONU.

8. The method according to any one of the preceding claims, further comprising: A checking routine is run on the collected upstream transmission opportunities, wherein the checking routine includes at least searching for mathematical errors in the collected upstream transmission opportunities.

9. A method according to any one of the preceding claims, wherein: The optical distribution network is part of a mobile network, wherein the upstream transmission opportunity defines a target bandwidth allocated to a mobile antenna at a certain point in time, and the method further comprises: - comparing the target bandwidth allocated to the mobile antenna with the bandwidth required by the mobile antenna at the point in time.

10. The method according to any one of the preceding claims, further comprising: - encapsulating the layer 3 output payload as a payload in an upstream packet, and - sending said upstream packets in an upstream direction through said optical distribution network to an optical line terminal, OLT, for inspection of said layer 3 output payload at said OLT.

11. A network unit for an optical distribution network, the network unit comprising components for performing the following operations: receiving downstream data packets in a downstream frame, each downstream data packet comprising a layer 2 header, the layer 2 header comprising at least an upstream transmission opportunity and a corresponding allocation identifier, wherein: Each allocation identifier identifies a T-CONT of an ONU of the optical distribution network, wherein the upstream transmission opportunity defines an upstream bandwidth allocation for the T-CONT of the ONU; extracting at least a portion of the upstream transmission opportunity and its corresponding allocation ID from the layer 2 header; and The at least a portion of the upstream transmission opportunities and the corresponding allocation IDs are collected for transmission as a layer 3 output payload.

12. The network element according to the preceding claim, further comprising means for storing the layer 3 output payload in a memory of the network element.

13. The network unit according to any one of claims 11 to 12, further comprising means for performing the following operations: The layer 3 output payload is sent to a user output port of the network element for further processing, for example, by a computer coupled to the network element.

14. The network unit according to any one of claims 11 to 13, further comprising means for performing the following operations: encapsulating the layer 3 output payload as a payload in an upstream packet, and The upstream packets are sent in an upstream direction through the optical distribution network to an optical line terminal, OLT, for inspection of the layer 3 output payload at the OLT.

15. The network unit according to any one of claims 11 to 14, wherein: The optical distribution network is part of a mobile network, wherein the upstream transmission opportunity defines a target bandwidth allocated to a mobile antenna at a certain point in time, and the network unit further includes a component for performing the following operations: comparing the target bandwidth allocated to the mobile antenna with the bandwidth required by the mobile antenna at the point in time.

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