The implementation of optical packet-switched networks requires that the problems of resource contention, signalling and local and global synchronization be resolved. A possible optical solution to resource contention is based on the use of switching matrices suitably connected with optical delay lines. Signalling could be dealt with using subcarrier multiplexing of packet headers. Synchronization could take advantage of clock tone multiplexing techniques, digital processing for ultra-fast clock recovery, and new distributed techniques for global packet-slot alignment. To explore the practical feasibility and effectiveness of these key techniques, a consortium was formed among the University of Massachusetts, Stanford University, and GTE Laboratories. The consortium, funded by ARPA, has three main goals: investigating networking issues involved in optical contention resolution (University of Massachusetts), constructing an experimental contention-resolution optical (CRO) device (GTE Laboratories), and building a packet-switched optical network prototype employing a CRO and novel signaling/synchronization techniques (Stanford University). This paper describes the details of the project and provides an overview of the main results obtained so far.

CORD: contention resolution by delay lines

A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

WDM optical network with passive pass-through at each node

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

An ultra-low latency optical router with a peta-bit-per-second total aggregate switching bandwidth, that will scale to a total connectivity of 1000 by 1000, and beyond by modular upgrades, that utilizes advanced optical technologies to achieve such high capacity with two to three orders of magnitude less volume and power requirements than the electrical router counter part, that serves as a universal engine to other optical routers being developed by vendors and researchers today, that can function in the context of circuit-switching, flow-switching, burst-switching, and packet-switching, that uses advanced wavelength conversion technology to effectively achieve three methods of contention resolution in the router: deflection in wavelength, deflection in space, and buffering in time, and that interfaces a local network to the Supernet.

Ultra-low latency multi-protocol optical routers for the next generation internet

As optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and the data payload propagate through network elements with the same path and the associated delays. The header routing information has sufficiently different characteristics from the data payload so that the signaling header can be detected without being affected by the data payload, and that the signaling header can also be removed without affecting the data payload. The signal routing technique can overlaid onto the conventional network elements in a modular manner using two types of applique modules. The first type effects header encoding and decoding at the entry and exit points of the data payload into and out of the network; the second type effects header detection at each of the network elements.

High-throughput, low-latency next generation internet networks using optical label switching and high-speed optical header generation, detection and reinsertion

A dynamic control mechanism, based on subcarrier-multiplexed pilot-tones and acoustooptic tunable filters, is proposed for wavelength routing in a high-capacity wavelength division multiplexed (WDM) SONET interoffice ring network. The authors experimentally verified the network concept and discussed different network applications for bursty data traffic and continuous voice/video traffic. >

J. J. Johnson

Papers

A self-routing WDM high-capacity SONET ring network

Self-routing WDM high-capacity SONET ring network