Ciena

About: Ciena is a company organization based out in Hanover, Maryland, United States. It is known for research contribution in the topics: Signal & Node (networking). The organization has 1259 authors who have published 1557 publications receiving 25989 citations.

Bidirectional WDM optical communication systems with bidirectional optical amplifiers

Abstract: The present invention provides a bidirectional WDM optical communication system with bidirectional optical amplifiers for optically amplifying two counter-propagating WDM optical signals. The bidirectional system includes two sets of optical transmitters for respectively creating a set of west-east optical channels and a set of counter-propagating east-west optical channels. The respective channel sets are multiplexed by optical combiners and output to an optical transmission path. A bidirectional optical amplifier positioned in the optical transmission path amplifies the west-east and east-west WDM signals. In an exemplary embodiment, the amplifier includes at least two optical circulators with at least first, second, and third circulating ports. A gain block interconnects the circulators for optically amplifying the WDM signals. Bragg gratings configured to reflect either the west-east or the east-west channel band are positioned in optical paths which optically communicate with the optical circulators. The bidirectional WDM optical system further includes two receiving systems for demultiplexing the WDM signals and routing the individual optical channels to their respective receivers.

WDM optical communication systems with wavelength stabilized optical selectors

Abstract: The present invention provides a wavelength division multiplexed optical communication system with dynamically stabilized wavelength selectors. To accurately correlate the wavelength of a wavelength selector to the wavelength emitted by an optical transmission source, the present invention uses an optical detector and feedback loop to optimize the wavelength of an optical selection element in accordance with a wavelength of an incident optical channel. In one embodiment, the optical selection element is a Bragg grating associated with a grating wavelength controller, such as a temperature regulator or strain tuning system, to adjust the wavelength band of maximum reflectivity of the grating. The feedback loop communicates with the optical detector and the wavelength controller to modify the grating's reflection wavelength band in accordance with the wavelength of an incident optical channel.

Tracking distributed data retrieval in a network device

Abstract: The present invention provides a method and apparatus for tracking distributed statistical data retrieval in a network device. Periodically, statistical data is gathered by processes on one or more remote cards in a network device and transferred to a central process. The distributed processes register each different type of statistical data to be gathered with the central process allowing the central process to maintain an accurate inventory of distributed processes expected to send particular statistical data. Tracking statistical data gathering processes allows the central process to consistently report data while allowing each process to remain modular. In addition, tracking increases a network device's scalability. For example, new processes may be added to a network device without affecting existing processes. Moreover, tracking increases a network device's availability. For instance, tracking provides fault tolerance, such that if one statistical data gathering process fails the other statistical data gathering processes are not affected and data continues to be reported. Importantly, data not reported by a registered process may be quickly detected and, where necessary, reported to a network management system. Tracking also provides for auto deregistration, for example, when hot swapping of cards out of a network device, tracking deregisters processes as necessary.

Packet and circuit network convergence with OpenFlow

Abstract: IP and Transport networks are controlled and operated independently today, leading to significant Capex and Opex inefficiencies for the providers. We discuss a unified approach with OpenFlow, and present a recent demonstration of a unified control plane for OpenFlow enabled IP/Ethernet and TDM switched networks.

Out-of-band network management channels

Abstract: The present invention provides a method and apparatus for improving management and network availability by providing out-of-band management channels between network/element management system (NMS) clients and servers. High priority client requests and server notifications may be sent over the out-of-band management channels to ensure fast response times. In addition, periodic roll calls between NMS clients and NMS servers may be executed over the out-of-band management channels to allow for quick discovery of any disconnects and reclaiming associated client resources. Further, periodic roll calls may be conducted between the NMS servers and the network devices to which they are connected, and if a server discovers that a network device has gone down, it may send a high priority notification to appropriate NMS clients over the out-of-band management channels to ensure a fast response by the clients. Sending high priority messages over out-of-band management channels maximizes client/server management availability and, hence, network availability.