Massachusetts Institute of Technology

At&t Bell Laboratories

Digital Equipment Corporation

Robert G Gallager

Muriel Medard

Alan Joseph Kirby

Adel A Saleh

Richard A Barry

Steven G Finn

Vincent W Chan

A method and apparatus for generating first and second tree topologies for any source node in a network which can be represented as a node or an edge redundant graph, such that any node in the graph remains connected to the source node via at least one tree even after the failure of a node or an edge. This technique provides a recovery mechanism upon detection of a failure in a network.

Method and apparatus for automatic protection switching

There is disclosed the architecture for an all optic network which employs a three level hierarchy using wavelength vision multiplexing. At the lowest level of the hierarchy are Level-0 all optical networks. The Level-0 networks are 'local' broadcast networks each of which supports a plurality of access ports and each access port can hear all the local traffic transmitted by all other access ports in the same Level-0 network. Each Level-0 network shares wavelengths internally, but there is extensive reuse of wavelengths among different Level-0 networks. The next higher level, which is the intermediate level, Level-1, is essentially a wavelength router coupled with one or more of the Level-0 networks to provide a wavelength path to one or more directly connect Level-0 networks or, in combination with a Level-2 network, a light path to one or more Level-0 network outside itself. The Level-2 are second level wavelength routing networks which provide light paths, as opposed to wavelength paths, between Level-1 networks. The Level-2 networks may be as simple as fiber trunks alone or they may employ frequency changing devices in addition to wavelength routers and/or spatial switches.

All-optical network architecture

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Winchester, MA, United States of America

Robert G Gallager