A method for assigning a network path after receiving a connection request to connect a first node with a second node of a network. The method including evaluating a network utilization parameter of the network, such as a network load or blocking probability, at that point in time. If the network utilization parameter is below a minimum threshold level, the method includes carrying out the steps of identifying a set of n network paths through the network that connect the first node with the second node and are absent non-linear links, performing network path selection by selecting p network paths from the set of n network paths that have the best linear OSNR, and, selecting a network path from the set of p network paths that balances the wavelength utilization between the first node and the second node of a network.

It is difficult in an optical network to achieve fault recovery in case of multiple failures without decreasing the usage efficiency of the optical network; therefore, an optical communication system according to an exemplary aspect of the present invention includes an optical network management device including an optical path setting means for setting, to a physical route differing from each other, a backup path corresponding to each of a plurality of active paths on an identical physical route, and a failure-case optical path setting means for setting a failure-case backup path with a compressed band of the backup path, to a physical route without a failure in a case where failures arising on more than one physical route among the physical routes; and an optical node device including an optical transceiver means for transmitting and receiving optical signals using failure-case backup path information resulting from setting by the failure-case optical path setting means.

The invention discloses a communication method includes: receiving, by the ONU by using the first port or the second port, a wavelength switching request message delivered by the OLT, where the wavelength switching request message carries second wavelength channel information and port information that is of the second port; switching, by the ONU, an operating wavelength channel of an optical module connected to the second port from a first wavelength channel to a second wavelength channel corresponding to the second wavelength channel information; and sending, by the ONU, a wavelength switching complete message to the OLT by using the first port. According to the communication method provided in embodiments of the present invention, quick wavelength switching is performed based on the second port, so that a service is not interrupted in a wavelength switching process, and user experience is better.

As network traffic grows and more data needs to be transmitted through a network, it is desired to use optical switching systems that allow for switching between a large number of nodes. An optical switching system according to one embodiment disclosed herein allows different nodes to transmit optical signals having the same optical wavelength, in order to accommodate a larger number of nodes. For example, one cluster of nodes may transmit data using optical wavelengths that are the same as optical wavelengths that may also be used by other clusters of nodes. A controller performs scheduling and reconfiguration in the optical switching system, as needed, e.g. in order to mitigate collisions.

Systems and methods for adaptive and automated traffic engineering of data transport services may include learning the demand between devices and data paths based on application workloads, prediction of traffic demand and paths based on the workload history, provisioning and management of data paths (i.e. network links) based on the predicted demand, and real-time monitoring and data flow adaptation. Systems and methods for adaptive and automated traffic engineering of data transport services may also include learning the variation of traffic (data flow in the network) on various links (data paths) of the network topology using historical data (e.g. a minute, an hour, a day, or a week of data), predicting the data flow pattern for a time interval, and provisioning the services to steer data to meet the application requirements and other network wide goals (e.g., load balancing).

In general, techniques are described for dynamically determining a logical network topology for more efficiently transporting network traffic over a physical topology based on end-to-end network traffic demands and optical transport network (OTN) characteristics of the network. The techniques may be applicable to meeting network traffic demands placed upon a multi-layer network having a base transport layer and a logical or overlay Internet Protocol (IP) layer routed on the transport layer.

In an optical communication network that includes a plurality of interconnected network nodes, a method includes storing in each network node, and for each communication channel that traverses the node, one or more impairment margins of respective impairments that affect the communication channel. A potential communication channel that traverses a subset of the nodes in the network is identified. A quality of the potential communication channel is evaluated by processing the impairment margins stored in the nodes in the subset.

Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.

Optical protection switching apparatus (10), for a single fibre bidirectional WDM optical ring, comprising: first (12) and second (14) ports for coupling to first and second adjacent portions of a single fibre bidirectional WDM optical ring; an optical splitter (16) comprising an input to receive a WDM aggregate optical signal, and first and second outputs coupled to the first and second ports; an optical switch (108) between the second output and the second port; and processing circuitry (24) to receive at least one of an indication of transmission continuity in the optical ring and an indication of transmission discontinuity in the optical ring, and to generate a switch control signal (20) comprising instructions to cause the optical switch to be open when there is transmission continuity in the optical ring and to cause the optical switch to be closed when there is transmission discontinuity in the optical ring.

A data centre network, comprises a first group of optical ports for connection to respective servers of a first group of servers; a second group of optical ports for connection to respective servers of a second group of servers; a first lower passive optical routing element arranged to route optical communication signals between the first group of optical ports and a first lower optical communication path; a second lower passive optical routing element arranged to route optical communication signals between the second group of optical ports and a second lower optical communication path; an upper passive optical routing element arranged to: (i) route optical communication signals between the first lower optical communication path and an upper optical communication path, and (ii) route optical communication signals between the second lower optical communication path and the upper optical communication path.