PERFORMING LOOKUP OPERATIONS USING ASSOCIATIVE MEMORIES OPTIONALLY INCLUDING MODIFYING A SEARCH KEY IN GENERATING A LOOKUP WORD AND POSSIBLY FORCING A NO-HIT INDICATION IN RESPONSE TO MATCHING A PARTICULAR ENTRY

US7103708B2 · kind B2 · utility

Assignee

• Cisco Technology, Inc. · US

Inventors

• William N. Eatherton · San Jose, US
• Jaushin Lee · Saratoga, US
• Bangalore Priyadarshan · Fremont, US
• Priyank Ramesh Warkhede · Redmond, US
• Fusun Ertemalp · Menlo Park, US
• Hugh W. Holbrook · Palo Alto, US
• Dileep K. Devireddy · San Jose, US
• Bhushan Mangesh Kanekar · Saratoga, US
• Venkateshwar Rao Pullela · San Jose, US

Key dates

• Filing date: Aug 10, 2002
• Grant date: Sep 5, 2006
• Expiry date: Mar 18, 2023

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F16/90339
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

Methods and apparatus are disclosed for performing lookup operations using associative memories, including, but not limited to modifying search keys within an associative memory based on modification mappings, forcing a no-hit condition in response to a highest-priority matching entry including a force no-hit indication, selecting among various sets or banks of associative memory entries in determining a lookup result, and detecting and propagating error conditions. In one implementation, each block retrieves a modification mapping from a local memory and modifies a received search key based on the mapping and received modification data. In one implementation, each of the associative memory entries includes a field for indicating that a successful match on the entry should or should not force a no-hit result. In one implementation, an indication of which associative memory blocks or sets of entries to use in a particular lookup operation is retrieved from a memory.