A communications network including nodes which permit networks to be tunnelled across intermediate networks. The present invention has application, in particular, to SDH networks, SONET and OTN. The content of entities for transportation across an existing network are mapped into a series of subframes and are virtually concatenated across the network. Each subframe is assigned a sequence indicator, which allows the original entity to be assembled at a remote node.

Method and apparatus for tunnelling data in a network

A compact, low-crosstalk 8/spl times/8 optical matrix switch module has been developed. A thermooptic switch chip and driving circuits with TTL interfaces are integrated on a 100-mm/sup 2/ ceramic substrate. It achieved a low insertion loss of 10.0 dB, a low crosstalk level of -25.9 dB, and had excellent stability in practical operation. A photonic intermodule connector for electronic switching systems in the near future is also demonstrated through the use of these optical switch modules. >

Silica-based 8/spl times/8 optical matrix switch module with hybrid integrated driving circuits and its system application

We study dynamically rearrangable end-to-end transport networks by means of SDH/SONET and/or ATM virtual paths. The concept and its advantages are brie y reviewed and we propose a new algorithm for designing such networks. Our algorithm provides integer solutions, handles non-linear equivalent bandwidths, finds its own paths, and allows for an arbitrary design optimisation criterion. It is found to perform equal to or better than an earlier, comparable though more restricted, algorithm. We also put forward a strategy for managing virtual paths in real time. It consists of a repeated cycle of on-line measurement of offered traffics followed by the design and implementation of a new virtual path network. Methods and parameters for traffic measurements and network updating frequency are studied and optimised. Applying the strategy to rearrangeable networks subject to variable traffics in a simulator, we discover considerable gains and a robustness in our parameter settings.

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Management of Reconfigurable Virtual Path Networks

The requirement of a separate payload clock in an ATM system is eliminated by increasing the number of bytes in an ATM cell and controllably generating and inserting idle cells so that a clock rate equal to that of the incoming SDH, SONET or the like clock rate may be used as a read clock. In one embodiment, the number of cells in a predetermined interval, for example 125 μsec., is adjusted to be a predetermined integer number by inserting idle cells. This, in turn, allows the use of a "standard" available clock to delineate cell boundaries.

Asynchronous transfer mode (ATM) payload synchronizer

A method and apparatus for cross-connecting arbitrary fragments of an incoming virtual tributary synchronous payload envelope, or arbitrary fragments of any incoming transmission stream, at a cross-connect element within a communications network is provided without incurring a delay associated with aligning a frame phase of the first digital stream to any arbitrary frame timing reference The arbitrary fragments are sized smaller than a complete virtual tributary, or equivalent thereof, of the first digital stream, and comprise one or more incoming payload bytes The incoming payload bytes have incoming identifiers related to their incoming locations and outgoing identifiers related to their outgoing locations One method achieves this cross-connect by looking up pre-recorded cross-connect information for the fragments in a cross-connect map memory at fixed sequence storage locations related to the incoming identifiers at times synchronous with the incoming first digital transmission stream, presenting outgoing identifiers provided by the cross-connect map memory to an addressing input of the payload memory at times synchronous with the incoming fragments so as to store the incoming fragments in a payload memory in an order to be synchronous with an outgoing second digital transmission stream, and then reading the stored fragments from the payload memory from a fixed sequence of storage locations related to the outgoing identifiers at times synchronous with the outgoing second digital transmission stream This cross-connect avoids any delay associated with first aligning or locking a frame phase of the incoming stream with any arbitrary frame timing reference

DSO cross-connect for floating virtual tributaries

The main concepts and interfacing and multiplexing techniques for an NNI (network node interface) as set forth in CCITT (International Consultive Committee for Telephone and Telegraph) Recommendations are described. The objectives and history of the NNI standardization are reviewed together with concepts, basic requirements, and features of the NNI. The nine-row-based frame structure and the virtual container (VC) concept, which are the main features of the NNI, are introduced. The multiplexing principle and method, the detailed frame structure and overhead, and mapping methods related to the NNI are described. Applications of the NNI in the synchronous network and international interworking are presented. The future application of asynchronous transfer mode (ATM) is discussed. >

Keith R. Harrison

Papers

CCITT standardization of network node interface of synchronous digital hierarchy

CCITT standardization of network node interface of synchronous digital hierarchy