Prefix search circuitry and method
First Claim
1. A method of prefix search comprising:
- distributing prefix search keys to plural prefix search engines; and
at each search engine, reading data from a prefix search data tree structure stored in memory and, in a comparator, performing prefix search comparisons of search keys and data from the prefix search tree data structure to determine, in a forward pass of the tree data structure toward a leaf, memory addresses of nodes of the tree data structure to read the data from memory and obtain prefix search results,the method further comprising storing a prefix search tree data structure across plural banks of memory units and accessing the tree structure in successive read cycles, duplicate copies of internal nodes of the tree structure being stored in each of plural banks.
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Accused Products
Abstract
Prefix searches for directing internet data packets are performed in a prefix search integrated circuit. The integrated circuit includes an array of search engines, each of which accesses a prefix search tree data structure to process a prefix search. An SDRAM is dedicated to each search engine, and SDRAMs share address and control pins to plural search engines on the IC chip. Internal nodes of the tree data structure are duplicated across banks of the SDRAMs to increase bandwidth, and leaf nodes are stored across the SDRAM banks to reduce storage requirements. Within each search engine, data stored in a data register from an SDRAM is compared to a prefix search key stored in a key register. Based on that comparison, an address is calculated to access further tree structure data from the SDRAM. Packet descriptors containing search keys are forwarded to the search engines from an input queue and the search results are forwarded to an output queue, the same packet order being maintained in the two queues.
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Citations
6 Claims
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1. A method of prefix search comprising:
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distributing prefix search keys to plural prefix search engines; and at each search engine, reading data from a prefix search data tree structure stored in memory and, in a comparator, performing prefix search comparisons of search keys and data from the prefix search tree data structure to determine, in a forward pass of the tree data structure toward a leaf, memory addresses of nodes of the tree data structure to read the data from memory and obtain prefix search results, the method further comprising storing a prefix search tree data structure across plural banks of memory units and accessing the tree structure in successive read cycles, duplicate copies of internal nodes of the tree structure being stored in each of plural banks. - View Dependent Claims (2, 3, 4)
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5. A method of prefix search comprising:
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distributing prefix search keys to plural prefix search engines; and at each search engine, reading data from a prefix search data tree structure stored in memory and, in a comparator, performing prefix search comparisons of search keys and data from the prefix search tree data structure to determine, in a forward pass of the tree data structure toward a leaf, memory addresses of nodes of the tree data structure to read the data from memory and obtain prefix search results; the step of reading data further comprising; addressing a memory unit from each search engine over integrated circuit pins shared with another search engine; and reading the data in bursts over integrated circuit data pins dedicated to the search engine from the address locations in the memory unit. - View Dependent Claims (6)
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Specification