Flow-rate-regulated burst switches
First Claim
1. A method of burst switching comprising:
- receiving at a core controller of a fast-switching optical core node, connecting to a plurality of edge nodes, flow-rate requirements for a set of data streams, each data stream defined by a source edge node and a destination edge node;
determining, for said each data stream, a respective burst size;
determining, for said each data stream, a respective inter-burst interval;
presenting said respective burst size and said respective inter-burst interval to a scheduler for determining instants of time at which bursts belonging to said each data stream are to be received at the optical core node;
communicating indications of said respective burst size and said instants of time to a source edge node of said each data stream;
receiving, at each edge node, data packets of arbitrary sizes from respective data sources;
associating each data packet with a data stream from among a number S, S>
1, of predefined data streams;
segmenting each data packet into data segments each of a predefined maximum size;
storing said data segments and respective sizes into a data memory organized into K memory segments, K>
S, each for storing a data segment; and
storing in at least one control memory;
two stream-tracking arrays each having S entries and indicating an address in said data memory of a front data segment and a last data segment belonging to each of said S data streams;
a linkage array having K entries indicating addresses in said data memory of intervening data segments for each data stream; and
an occupancy tracking array indicating unused segments of said data memory.
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Abstract
Burst-switching nodes using a common-memory or a time shared space switch and employing flow-rate control are disclosed. Within a switching node, data bursts are segmented into data segments of a fixed size with some segments containing information bits as well as null bits. A switching node handles data streams allocated different flow rates and, for any data stream, the internal flow rate through the switching node can be higher than the external flow rate due to null padding of segmented data. The switching node is provided with a sufficient internal capacity expansion in order to offset the effect of null padding. A controller of the switching node is provided with a flow-rate-regulation apparatus to enable scheduling the transfer of data segments across the switching node in a manner that guarantees adherence to the allocated information flow rates.
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Citations
11 Claims
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1. A method of burst switching comprising:
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receiving at a core controller of a fast-switching optical core node, connecting to a plurality of edge nodes, flow-rate requirements for a set of data streams, each data stream defined by a source edge node and a destination edge node; determining, for said each data stream, a respective burst size; determining, for said each data stream, a respective inter-burst interval; presenting said respective burst size and said respective inter-burst interval to a scheduler for determining instants of time at which bursts belonging to said each data stream are to be received at the optical core node; communicating indications of said respective burst size and said instants of time to a source edge node of said each data stream; receiving, at each edge node, data packets of arbitrary sizes from respective data sources; associating each data packet with a data stream from among a number S, S>
1, of predefined data streams;segmenting each data packet into data segments each of a predefined maximum size; storing said data segments and respective sizes into a data memory organized into K memory segments, K>
S, each for storing a data segment; andstoring in at least one control memory; two stream-tracking arrays each having S entries and indicating an address in said data memory of a front data segment and a last data segment belonging to each of said S data streams; a linkage array having K entries indicating addresses in said data memory of intervening data segments for each data stream; and an occupancy tracking array indicating unused segments of said data memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification