Embodiments of the present disclosure are directed to systems and methods for allocating spectrum of a flexible-grid optical network to a plurality of virtual links. Given a set of optical channels of different line rates and channel widths, a user can reserve one of the optical channels as a long-term reservation. The user can later elect to downgrade its optical channel to a smaller optical channel with lower line rate and less spectrum, for example, when the user's traffic demands decrease. The user may return (e.g., sell or de-allocate) an amount of unused spectrum to the carrier, and the carrier creates and manages a resource pool to gather unused spectrum from users. When the user's traffic increases, the user may obtain (e.g., purchase) additional spectrum from the carrier's resource pool and/or upgrade the user's optical channel to an optical channel having a higher line rate.

Embodiments of the present invention provide an optical network unit ONU registration method, apparatus, and system, to resolve a problem in the prior art that a registration process is cumbersome. The method includes: receiving an uplink optical signal, where the uplink optical signal carries ONU authentication information; sending the optical signal to a corresponding MAC module separately according to a wavelength of uplink light; extracting, by the MAC module, the ONU authentication information, and sending the extracted ONU authentication information to a processor; and receiving, by the processor, the ONU authentication information, and determining whether the ONU authentication information is consistent with ONU authentication information configured by an OLT, where if the ONU authentication information is consistent with the ONU authentication information configured by the OLT, an ONU is registered successfully.

A method includes profiling user-network interface (UNI) ports including Optical channel Data Unit flex (ODUflex) in a network; and adapting, using a max-flow routing criterion, network-network interface (NNI) ports comprising ODUflex based on the profiling. A network includes a plurality of network elements; a plurality of links interconnecting the plurality of network elements, wherein the plurality of links includes Layer 0 Dense Wave Division Multiplexing (DWDM) bandwidth and Layer 1 Optical Transport Network (OTN) bandwidth; and a control plane operating between the plurality of network elements; wherein the Layer 0 DWDM bandwidth and the Layer 1 OTN bandwidth is statistically multiplexed using the control plane and manager based on monitoring bandwidth usage thereon over time.

A method for determining a bitrate allocation of a plurality of optical channels in an optical transmission link with discretized channel bitrates, the method comprising determining an initial discretized bitrate allocation and a corresponding initial power allocation for the plurality of optical channels for supporting the initial discretized bitrate allocation with the proviso that all optical channels meet a pre-defined optical signal-to-noise, OSNR, threshold for the respective initial discretized bitrate allocated to the respective optical channel; starting from the initial power allocation, varying, for an investigated optical channel of the plurality of optical channels, a channel power of the investigated optical channel to estimate a highest supported discretized bitrate for the investigated optical channel, wherein the highest supported discretized bitrate is the highest discretized bitrate for which the investigated optical channel meets a corresponding OSNR threshold; including the investigated optical channel in an upgrade candidate subset of the plurality of optical channels for potential bitrate upgrades based on the highest supported discretized bitrate exceeding the initial discretized bitrate for the investigated optical channel; and providing the upgrade candidate subset to an upgrade allocation algorithm.

A system for activating multi-rate optical network units (ONUs) includes an optical network having an optical line terminal (OLT) optically coupled to a plurality of ONUs, including one or more multi-rate ONUs configured to support multiple upstream rates. During discovery when other ONUs are permitted to transmit in the same quiet window, a multi-rate ONU that supports a higher rate is instead configured to send a discovery response at a sufficiently low rate so as not to require training of an equalizer, thereby allowing for a short preamble for the discovery response. Thereafter, during a quiet window for ranging when only the multi-rate ONU will be transmitting to prevent data collisions, the multi-rate ONU is transitioned to a higher rate and transmits a message with a sufficiently long preamble to train an equalizer at the OLT.