Apparatus and method for large scale ATM switching
First Claim
1. An optical switch for switching a succession of ATM cells, each ATM cell being received on one of a plurality of input lines and each being switched to one of a plurality of output lines to which it is directed as determined by an embedded identifier in each received cell, comprising:
- a plurality of input modules, each input module connected to a different subset of the plurality of input lines and each input module comprising a buffer for sequentially storing ATM cells received on the input lines to which it is connected and a tunable laser that is tunable to a plurality of different wavelengths;
a plurality of output modules, each output module connected to a different subset of the plurality of the output lines and each output module comprising an optical receiver fixed-tuned to receive one of the plurality of different wavelengths to which the tunable lasers in the input modules and tunable;
a contention resolution device electrically connected to each of said plurality of input modules for selecting from a head of queue of ATM cells stored in the buffer of each input module at most one ATM cell to be transmitted during a cell transmission time to each output module; and
an optical star coupler connecting said input modules and said output modules for simultaneously transmitting to each output module during each cell transmission time the ATM cells selected by the contention resolution device form the head of queue of ATM cells stored in the buffers of the input modules;
the tunable laser in each input module which has an ATM cell selected to be transmitted being tuned during each cell transmission time to the wavelength associated with the receiver of the output module connected to the output line to which the selected ATM cell is directed as determined by the embedded identifier in the selected ATM cell when received by one of the input modules.
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Abstract
Apparatus and method for large scale asynchronous transfer mode (ATM) switching utilizing tunable lasers and fixed-tuned receivers are provided. The apparatus, an optical switch, includes a plurality of input modules for receiving ATM cells to be switched and a plurality of output modules for outputting the switched ATM cells. The optical switch also includes an optical transmission network for optically transmitting each ATM cell from an input module to a particular output module, and a contention resolution device in electrical communication with the plurality of input modules for selecting the ATM cells from the plurality of input modules to be switched. Preferably, each output module includes a plurality of fixed-tuned receivers and each input module includes a plurality of tunable lasers. The fixed-tuned receivers of each output module are tuned to a particular wavelength so as to pass only those ATM cells optically received from the optical transmission network at the particular wavelength. The tunable lasers are tunable to a plurality of distinct wavelengths for optically transmitting the ATM cell to the optical transmission network at the particular distinct wavelength associated with the output module to which the ATM cell is destined.
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Citations
16 Claims
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1. An optical switch for switching a succession of ATM cells, each ATM cell being received on one of a plurality of input lines and each being switched to one of a plurality of output lines to which it is directed as determined by an embedded identifier in each received cell, comprising:
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a plurality of input modules, each input module connected to a different subset of the plurality of input lines and each input module comprising a buffer for sequentially storing ATM cells received on the input lines to which it is connected and a tunable laser that is tunable to a plurality of different wavelengths; a plurality of output modules, each output module connected to a different subset of the plurality of the output lines and each output module comprising an optical receiver fixed-tuned to receive one of the plurality of different wavelengths to which the tunable lasers in the input modules and tunable; a contention resolution device electrically connected to each of said plurality of input modules for selecting from a head of queue of ATM cells stored in the buffer of each input module at most one ATM cell to be transmitted during a cell transmission time to each output module; and an optical star coupler connecting said input modules and said output modules for simultaneously transmitting to each output module during each cell transmission time the ATM cells selected by the contention resolution device form the head of queue of ATM cells stored in the buffers of the input modules; the tunable laser in each input module which has an ATM cell selected to be transmitted being tuned during each cell transmission time to the wavelength associated with the receiver of the output module connected to the output line to which the selected ATM cell is directed as determined by the embedded identifier in the selected ATM cell when received by one of the input modules. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of switching a succession of ATM cells, each ATM cell being received on one of a plurality of input lines and each being switched to one of a plurality of output lines to which it is directed as determined by an identifier embedded in the received cell, different subsets of the output lines being associated with different fixed wavelengths, the method comprising the steps of:
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sequentially storing the ATM cells received on different subsets of the input lines; determining from the embedded identifier the destination subset of output lines of each ATM cell in a head of queue of stored ATM cells associated with each different subset of input lines; resolving contention between different cells at the head of queue of stored ATM cells that are directed at the same time to output lines in the same subset of output lines so that at most only one ATM cell is selected for transmission during a cell transmission time to the same subset of output lines; simultaneously optically transmitting to the different subsets of output lines over an optical star coupler during the cell transmission time each cell selected for transmission each at the wavelength associated with the subset of output lines to which the cell is directed as determined by the embedded identifier in the selected cell when received on one of the input lines; in each one of the different subsets of output lines filtering all the possible different transmission wavelengths other than the one fixed wavelength associated with that one subset of output lines. - View Dependent Claims (13, 14, 15, 16)
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Specification