US Patent No: 6,266,262

Number of patents in Portfolio can not be more than 2000

Enhanced binary content addressable memory for longest prefix address matching

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Abstract

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A modified binary content addressable memory (CAM) (700) having a fast variable prefix matching capability is disclosed. The modified CAM (700) includes modified CAM cells (702(0,0) to 702(n,m)), each of which includes a store/compare circuit (704(0,0) to 704(n,m)) for storing a data value and comparing the data value to a comparand value. In addition, each modified CAM cell (702(0,0) to 702(n,m)) further includes a multiplexer (MUX) circuit (706(0,0) to 706(n,m)). Each MUX circuit (706(0,0) to 706(n,m)) receives a non-shifted comparand value from a modified CAM cell of a previous row and same column, and a shifted comparand value from a modified CAM cell of the previous row and an adjacent column. The MUX circuits (706(0,0) to 706(n,m)) enable a comparand value to be shifted as it is applied to consecutive data values.

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Patent Owner(s)

Patent OwnerAddressTotal Patents
LARA NETWORKS, INC.SAN JOSE, CA24
LARA TECHNOLOGY, INC.SAN JOSE, CA13

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Medhekar, Ajit K San Jose, CA 11 411
Ramankutty, Jayan R Fremont, CA 1 61
Washburn, James G Palo Alto, CA 5 196

Cited Art Landscape

Patent Info (Count) # Cites Year
 
ADVANCED MICRO DEVICES, INC. (1)
4,928,260 Content addressable memory array with priority encoder 98 1988
 
HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P. (1)
5,014,195 Configurable set associative cache with decoded data element enable lines 102 1990
 
MITSUBISHI DENKI KABUSHIKI KAISHA (1)
4,975,873 Content addressable memory with flag storage to indicate memory state 47 1988
 
MUSIC SEMICONDUCTORS, INC. (1)
5,383,146 Memory with CAM and RAM partitions 130 1992
 
RAYTHEON COMPANY (1)
4,845,668 Variable field content addressable memory 82 1987
 
Triad Semiconductors International BV (1)
4,791,606 High density CMOS dynamic CAM cell 107 1987

Patent Citation Ranking

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Patent Info (Count) # Cites Year
 
NETLOGIC MICROSYSTEMS, INC. (54)
6,460,112 Method and apparatus for determining a longest prefix match in a content addressable memory device 45 1999
7,143,231 Method and apparatus for performing packet classification for policy-based packet routing 9 1999
6,539,455 Method and apparatus for determining an exact match in a ternary content addressable memory device 35 1999
6,499,081 Method and apparatus for determining a longest prefix match in a segmented content addressable memory device 52 1999
6,799,243 Method and apparatus for detecting a match in an intra-row configurable cam system 9 2000
6,795,892 Method and apparatus for determining a match address in an intra-row configurable cam device 6 2000
6,751,701 Method and apparatus for detecting a multiple match in an intra-row configurable CAM system 7 2000
6,400,593 Ternary CAM cell with DRAM mask circuit 24 2001
6,910,097 Classless interdomain routing using binary content addressable memory 14 2001
6,665,202 Content addressable memory (CAM) devices that can identify highest priority matches in non-sectored CAM arrays and methods of operating same 114 2001
6,944,709 Content addressable memory with block-programmable mask write mode, word width and priority 36 2001
6,934,795 Content addressable memory with programmable word width and programmable priority 42 2001
6,757,779 Content addressable memory with selectable mask write mode 77 2001
6,697,275 Method and apparatus for content addressable memory test mode 28 2001
7,054,993 Ternary content addressable memory device 6 2002
RE41351 CAM arrays having CAM cells therein with match line and low match line connections and methods of operating same 0 2002
6,892,272 Method and apparatus for determining a longest prefix match in a content addressable memory device 9 2002
6,574,702 Method and apparatus for determining an exact match in a content addressable memory device 23 2002
7,272,684 Range compare circuit for search engine 5 2002
7,111,123 Circuit and method to allow searching beyond a designated address of a content addressable memory 9 2002
7,206,212 Content addressable memory (CAM) device with entries having ternary match and range compare functions 5 2002
7,401,180 Content addressable memory (CAM) device having selectable access and method therefor 4 2002
6,988,164 Compare circuit and method for content addressable memory (CAM) device 7 2002
6,711,041 Content addressable memory with configurable class-based storage partition 20 2003
RE39227 Content addressable memory (CAM) arrays and cells having low power requirements 0 2003
6,831,850 Content addressable memory with configurable class-based storage partition 32 2003
7,272,027 Priority circuit for content addressable memory 1 2004
7,711,893 Range code compression method and apparatus for ternary content addressable memory (CAM) devices 13 2004
7,126,834 Sense amplifier architecture for content addressable memory device 8 2004
7,173,837 Content addressable memory (CAM) cell bit line architecture 8 2004
7,230,840 Content addressable memory with configurable class-based storage partition 2 2004
7,149,101 Method and apparatus for smoothing current transients in a content addressable memory (CAM) device with dummy searches 1 2004
7,277,983 Method and apparatus for smoothing current transients in a content addressable memory (CAM) device 3 2005
7,339,810 Device and method for ensuring current consumption in search engine system 3 2005
7,126,837 Interlocking memory/logic cell layout and method of manufacture 52 2005
7,251,147 Content comparator memory (CCM) device and method of operation 1 2005
7,246,198 Content addressable memory with programmable word width and programmable priority 10 2005
7,917,694 Method and system for finding maximal stripes in cache memory with content addressable memory 1 2005
7,814,266 Partial row expansion by logically combining range representation values in content addressable memory 1 2005
7,366,830 Row expansion reduction by inversion for range representation in ternary content addressable memories 7 2005
7,324,362 Content addressable memory cell configurable between multiple modes and method therefor 3 2006
7,298,635 Content addressable memory (CAM) cell with single ended write multiplexing 12 2006
7,450,409 Content addressable memory (CAM) cell having column-wise conditional data pre-write 4 2006
7,248,492 Method and apparatus for CAM with reduced cross-coupling interference 1 2006
7,555,594 Range representation in a content addressable memory (CAM) using an improved encoding scheme 9 2006
7,362,602 Sense amplifier circuit and method 3 2006
7,417,882 Content addressable memory device 0 2006
7,859,876 Method and apparatus for CAM with reduced cross-coupling interference 0 2007
7,545,661 Content addressable memory with twisted data lines 3 2007
7,545,660 Method and apparatus for CAM with reduced cross-coupling interference 1 2007
7,522,438 Method and apparatus for CAM with reduced cross-coupling interference 1 2007
8,073,856 System and method for efficiently searching a forwarding database that is split into a bounded number of sub-databases having a bounded size 0 2008
8,214,305 Pattern matching system and method for data streams, including deep packet inspection 0 2008
7,904,643 Range code compression method and apparatus for ternary content addressable memory (CAM) devices 1 2010
 
MICRON TECHNOLOGY, INC. (3)
6,781,856 Tertiary CAM cell 5 2002
6,996,664 Ternary content addressable memory with enhanced priority matching 1 2003
6,785,153 Tertiary CAM cell 5 2003
 
CISCO TECHNOLOGY, INC. (2)
7,155,563 Circuits to generate a sequential index for an input number in a pre-defined list of numbers 0 2004
7,162,572 Memory and power efficient mechanism for fast table lookup 11 2004
 
INTERNATIONAL BUSINESS MACHINES CORPORATION (1)
6,480,931 Content addressable storage apparatus and register mapper architecture 12 1999
 
RPX CORPORATION (1)
8,073,005 Method and apparatus for configuring signal lines according to idle codes 0 2007