Abstract: In general, techniques are described for inline packet replication in network devices. A network device referred to as an optical line terminal (OLT) may implement the techniques. The OLT comprises a customer interface that supports different logical interfaces to which couple a plurality of optical network terminals (ONTs) and a network interface that receives a data unit. The OLT further comprises a conversion unit, such as a media access control (MAC) module, located in a data path of the optical line terminal that determines whether the received data unit is a candidate for replication. The conversion unit includes an inline packet processing module that performs replication to generate at least one copy of the data unit based on the determination that the received packet is a candidate for packet replication. The customer interface outputs the at least one copy of the data unit to the ONTs.

Abstract: One or more devices of a network having asymmetric delay are configured to participate in time synchronization protocol sessions in which a client device synchronizes its local clock to a master device. In one example, a system includes an optical line terminal configured to receive a time synchronization protocol packet from a grandmaster clock and an optical network unit (ONU) configured to calculate a residence time of the time synchronization protocol packet, encode the residence time into the packet, and to forward the packet to a client device. Moreover, the system may participate in a plurality of time synchronization protocol sessions with a plurality of client devices, such that the client devices become synchronized in frequency and phase.

Abstract: In general, techniques are described for protecting optical networks from consecutive identical digit (CID) errors. An optical network device comprising a control unit and an interface may implement the techniques described in this disclosure. The control unit determines whether a data packet will result in a CID error prior to encapsulating at least a portion of the data packet to form a passive optical network (PON) frame and then, in response to the determination that the data packet will result in the CID error, modifies the data packet to form a modified data packet so that the modified data packet will not result in the CID error. The control unit encapsulates the modified data packet to form a PON frame. The control unit applies a scrambling polynomial to the PON frame to form a scrambled PON frame. The interface transmits the scrambled PON frame.

Abstract: One or more devices of a network having asymmetric delay are configured to participate in time synchronization protocol sessions in which a client device synchronizes its local clock to a master device. In one example, a system includes an optical line terminal configured to receive a time synchronization protocol packet from a grandmaster clock and an optical network unit (ONU) configured to calculate a residence time of the time synchronization protocol packet, encode the residence time into the packet, and to forward the packet to a client device. Moreover, the system may participate in a plurality of time synchronization protocol sessions with a plurality of client devices, such that the client devices become synchronized in frequency and phase.

Abstract: Techniques are disclosed that relate to synchronizing a clock on a network interface device with a clock on an optical line terminal (OLT). In one example, the technique to synchronizing the clocks may include monitoring one or more instances when the network interface device transmits information to the OLT and determining when a frame should be received by the network interface device based on the monitored one or more instances when the network interface device transmits information the OLT.

Abstract: Techniques are disclosed that relate to synchronizing a clock on a network interface device with a clock on an optical line terminal (OLT). In one example, the technique to synchronizing the clocks may include monitoring one or more instances when the network interface device transmits information to the OLT and determining when a frame should be received by the network interface device based on the monitored one or more instances when the network interface device transmits information the OLT.

Abstract: An example method includes encapsulating, by an optical network device, at least a portion of a data packet to form a passive optical network (PON) frame. The method further includes applying, by the optical network device, a scrambling polynomial to at least a portion of the PON frame to generate a scrambled PON frame. The method further includes determining, by the optical network device, that the scrambled PON frame comprises a consecutive identical digit (CID) sequence greater than a threshold length. The method further includes replacing, by the optical network device the determined CID sequence with a correction pattern to generate a modified scrambled PON frame. The method further includes transmitting, by the optical network device, the modified scrambled PON frame.

Abstract: The disclosure presents techniques for merging multiple data flows in a network such as a Passive Optical Network (PON). The PON comprises an interface module and network nodes connected to the interface module via an optical fiber link. Each network node further serves client devices. The client devices request multiple data flows, requiring the interface module to serve multiple data flows to a network node for delivery to the devices. The interface module merges received data flows to permit multiple flows to be processed by a single segmentation and reassembly (SAR) engine, reducing hardware cost and complexity within the node. However, subunits associated with different data flows within a merged data flow are not interleaved with one another. Instead, the subunits associated with an original unit of information are transmitted contiguously within the merged data flow, facilitating identification and reassembly of the subunits for a particular microflow.

Abstract: In general, techniques are described for protecting optical networks from consecutive identical digit (CID) errors. An optical network device comprising a control unit and an interface may implement the techniques described in this disclosure. The control unit determines whether a data packet will result in a CID error prior to encapsulating at least a portion of the data packet to form a passive optical network (PON) frame and then, in response to the determination that the data packet will result in the CID error, modifies the data packet to form a modified data packet so that the modified data packet will not result in the CID error. The control unit encapsulates the modified data packet to form a PON frame. The control unit applies a scrambling polynomial to the PON frame to form a scrambled PON frame. The interface transmits the scrambled PON frame.

Abstract: An example method includes encapsulating, by an optical network device, at least a portion of a data packet to form a passive optical network (PON) frame. The method further includes applying, by the optical network device, a scrambling polynomial to at least a portion of the PON frame to generate a scrambled PON frame. The method further includes determining, by the optical network device, that the scrambled PON frame comprises a consecutive identical digit (CID) sequence greater than a threshold length. The method further includes replacing, by the optical network device the determined CID sequence with a correction pattern to generate a modified scrambled PON frame. The method further includes transmitting, by the optical network device, the modified scrambled PON frame.

Abstract: In general, techniques are described for inline packet replication in network devices. A network device referred to as an optical line terminal (OLT) may implement the techniques. The OLT comprises a customer interface that supports different logical interfaces to which couple a plurality of optical network terminals (ONTs) and a network interface that receives a data unit. The OLT further comprises a conversion unit, such as a media access control (MAC) module, located in a data path of the optical line terminal that determines whether the received data unit is a candidate for replication. The conversion unit includes an inline packet processing module that performs replication to generate at least one copy of the data unit based on the determination that the received packet is a candidate for packet replication. The customer interface outputs the at least one copy of the data unit to the ONTs.

Abstract: This disclosure is directed to techniques for facilitating clock recovery in optical networks. An optical network terminal (ONT) that terminates a fiber link of an optical network includes a clock mode selection module that automatically selects a clock recovery mode based on a type of optical network to which the ONT connects and a type of service provided to one or more subscriber devices coupled to the ONT. By automatically selecting the clock recovery module, an administrator or other user need not provision this aspect of the optical network, thereby reducing administrative tasks and facilitating the provisioning of the optical network. In addition, the techniques enable selection of the most optimal clock recovery mode based on the current state of the optical network.

Abstract: Techniques are disclosed that relate to synchronizing a clock on a network interface device with a clock on an optical line terminal (OLT). In one example, the technique to synchronizing the clocks may include monitoring one or more instances when the network interface device transmits information to the OLT and determining when a frame should be received by the network interface device based on the monitored one or more instances when the network interface device transmits information the OLT.

Abstract: This disclosure is directed to devices and methods for facilitating the upgrade of optical networks. An optical network terminal (ONT) that terminates an optical fiber link of an optical network comprises two or more transport engines that each converts data transmitted via different transports to data corresponding to a service. For example, the ONT may include a first transport engine and a second transport engine. The first transport engine converts data received over the optical network via a first transport, e.g., a legacy transport, into data corresponding to a service for one or more subscriber devices. The second transport engine converts the data received over the optical network via a second transport, e.g., a next generation transport, into the data corresponding to the service for the subscriber devices. The ONT is selectively configurable to select one of the first and second transport engines, thereby making the ONT upgrade-resilient.

Abstract: In general, techniques are described for inline packet replication in network devices. A network device referred to as an optical line terminal (OLT) may implement the techniques. The OLT comprises a customer interface that supports different logical interfaces to which couple a plurality of optical network terminals (ONTs) and a network interface that receives a data unit. The OLT further comprises a conversion unit, such as a media access control (MAC) module, located in a data path of the optical line terminal that determines whether the received data unit is a candidate for replication. The conversion unit includes an inline packet processing module that performs replication to generate at least one copy of the data unit based on the determination that the received packet is a candidate for packet replication. The customer interface outputs the at least one copy of the data unit to the ONTs.

Abstract: The disclosure presents techniques for merging multiple data flows in a network such as a Passive Optical Network (PON). The PON comprises an interface module and network nodes connected to the interface module via an optical fiber link. Each network node further serves client devices. The client devices request multiple data flows, requiring the interface module to serve multiple data flows to a network node for delivery to the devices. The interface module merges received data flows to permit multiple flows to be processed by a single segmentation and reassembly (SAR) engine, reducing hardware cost and complexity within the node. However, subunits associated with different data flows within a merged data flow are not interleaved with one another. Instead, the subunits associated with an original unit of information are transmitted contiguously within the merged data flow, facilitating identification and reassembly of the subunits for a particular microflow.

Abstract: The disclosure presents techniques for merging multiple data flows in a network such as a Passive Optical Network (PON). The PON comprises an interface module and network nodes connected to the interface module via an optical fiber link. Each network node further serves client devices. The client devices request multiple data flows, requiring the interface module to serve multiple data flows to a network node for delivery to the devices. The interface module merges received data flows to permit multiple flows to be processed by a single segmentation and reassembly (SAR) engine, reducing hardware cost and complexity within the node. However, subunits associated with different data flows within a merged data flow are not interleaved with one another. Instead, the subunits associated with an original unit of information are transmitted contiguously within the merged data flow, facilitating identification and reassembly of the subunits for a particular microflow.

Abstract: This disclosure is directed to techniques for facilitating clock recovery in optical networks. An optical network terminal (ONT) that terminates a fiber link of an optical network includes a clock mode selection module that automatically selects a clock recovery mode based on a type of optical network to which the ONT connects and a type of service provided to one or more subscriber devices coupled to the ONT. By automatically selecting the clock recovery module, an administrator or other user need not provision this aspect of the optical network, thereby reducing administrative tasks and facilitating the provisioning of the optical network. In addition, the techniques enable selection of the most optimal clock recovery mode based on the current state of the optical network.

Abstract: This disclosure is directed to devices and methods for facilitating the upgrade of optical networks. An optical network terminal (ONT) that terminates an optical fiber link of an optical network comprises two or more transport engines that each converts data transmitted via different transports to data corresponding to a service. For example, the ONT may include a first transport engine and a second transport engine. The first transport engine converts data received over the optical network via a first transport, e.g., a legacy transport, into data corresponding to a service for one or more subscriber devices. The second transport engine converts the data received over the optical network via a second transport, e.g., a next generation transport, into the data corresponding to the service for the subscriber devices. The ONT is selectively configurable to select one of the first and second transport engines, thereby making the ONT upgrade-resilient.

Abstract: The disclosure is directed to techniques for merging multiple data flows in a Passive Optical Network (PON). The PON comprises an interface module and a plurality of network nodes connected to the interface module via an optical fiber link. Each of the network nodes further serves client devices. The client devices request multiple data flows, requiring the interface module to serve multiple data flows to a network node for delivery to the devices. The interface module merges received data flows to permit multiple flows to be processed by a single segmentation and reassembly (SAR) engine, reducing hardware cost and complexity within the node. However, subunits associated with different data flows within a merged data flow are not interleaved with one another. Instead, the subunits associated with an original unit of information are transmitted contiguously within the merged data flow, facilitating identification and reassembly of the subunits for a particular microflow.