The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 18, 2000
Filed:
Feb. 24, 1998
George Frank Irwin, Kanata, CA;
Nortel Networks Corporation, Montreal, CA;
Abstract
An apparatus for performing an address lookup to find a longest matching prefix for an N-bit input address in a packet data communication system that includes a memory (e.g. RAM) for storing a table containing a predefined portion of an N-bit address with an associated prefix search list containing prefix values that are candidates for the longest matching prefix. A binary search algorithm is used for selecting a specific prefix value from the prefix search list to structure the N-bit input address to form a search value. A search algorithm (e.g. a content addressable memory) is used for performing an associative search on the search value to find the longest matching prefix. The two types of memories (RAM and CAM) each provide specific functions. The RAM is used as a lookup table to provide an N/x-bit (0<x<N) binary decoding tree, and the CAM is used to provide an associative search of network addresses that are stored in logical bins that have a specific network prefix. By using the binary search algorithm that is guided by the lookup table data, the CAM can be probed to find the longest matching prefix.