Alcatel Lucent

Lucent Technologies Inc.

Alcatel-lucent USA Inc.

Anthony Vernon Walker Smith

Douglas Rider

James Craig Slezak

Jonathan Titchener

Kotikalapudi Sriram

John Peter Guy

Mukul Katiyar

Rajender Rao Nednur

Robert Alain Nadon

The method of placing regenerators along a trail connecting a source network node with a destination network node of an automatically switched optical network first identifies N tentative regeneration sites and n+1 optical paths along the trail. Wavelengths are assigned to each optical path, and the performance of the trail is assessed based on regenerator placement data and wavelength assignment data.

Regenerators placement mechanism for wavelength switched optical networks

The method of placing regenerators along a trail connecting a source network node with a destination network node of an automatically switched optical network first identifies N tentative regeneration sites and n+1 optical paths along the trail. Wavelengths are assigned to each optical path; and the performance of the trail is assessed based on regenerator placement data and wavelength assignment data. The data identifying this regenerator path, namely regenerator placement data, the wavelength assignment data and the performance parameter of the trail are stored in a list, if the performance parameter is over a threshold. Selection of the tentative sites is revised whenever the initial placement fails due to a reach problem, a wavelength-blocking problem or a path quality problem. If the time for revising the initial placement, or the cost of a regenerator path is unacceptable, the regenerator path is abandoned and a further placement is initiated. Next, a further regenerator placement is attempted for the same trail using n+1 regenerators, and the further regenerator path is stored in the list, etc. Still further, regenerator placement is attempted for another trail, and so on, until a specified number of regenerator paths are stored in the list.

In an automatically switched optical network, the wavelengths are assigned to optical path based on their intrinsic physical performance and on the current network operating parameters. The wavelength performance information is organized in binning tables, based primarily on the wavelength reach capabilities. A network topology database provides the distance between the nodes of the network, which is used to determine the length of the optical path. Other network operating parameters needed for wavelength selection are also available in this database. Once a bin corresponding to the path length is identified in the binning table, the wavelength for that path is selected based on length only, or based on the length and one or more additional parameters. The optical path performance is estimated for the selected wavelength, and the search continues if the estimated path performance is not satisfactory. Several available wavelengths are searched and of those, the wavelength that is most used along the optical path in consideration or alternatively network-wide is selected and assigned. This method helps minimize wavelength fragmentation. The binning tables may have various granularities, and may be organized by reach, or by reach, wavelength spacing, the load on the respective optical path, the fiber type, etc.

Dynamic assignment of wavelengths in agile photonic networks

The routing cycles method establishes a connection between a source network node and a destination network node based on a cycles graph. For each connection request, the network identifies 'k' valid solution cycles on the cycles graph, taking into account any constraints imposed by the type of routing requested. Each valid solution cycle is then split into a pair of routes, which are validated against explicit constraints received with the request, if any. The performance of each pair is then estimated and the pairs are ordered in a list based on their performance. The pair ordering is carried out based on the cost of the routes and on the chance of a successful set-up, which is given by an estimated Q factor. The network attempts to set up the connection according to the class of service for the respective request, first along the best route(s) from the list. Failing this, it will try the second best route(s), etc.

Routing cycles for wavelength switched optical networks

A connection between a source node and a destination node is automatically routed and switched in a WDM photonic network, on receipt of a connection request. A switching and routing mechanism selects a plurality of valid link paths using a path tree, where invalid branches are eliminated based on constraints received in the connection request, and on a link and path cost functions. A regenerator placement tree is used for determining a plurality of viable regenerator paths for each valid link path. On the regenerator placement tree, non-viable branches are eliminated based on constraints received with the request and on regenerator availability at the intermediate nodes along the respective path, and on the specification of these available regenerators. Next, the switching and routing mechanism assigns a set of wavelengths to each viable regenerator path, and estimates the performance of the path using a Q estimator. The regenerator paths are ordered according to their performance and the switching and routing mechanism attempts to setup a paths to serve the request, starting with the best path.

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Anthony Vernon Walker Smith