Cisco Technology, Inc.

Priyank Ramesh Warkhede

William Norman Eatherton

Jaushin Lee

Fusun Ertemalp

Bangalore Priyadarshan

Dileep Kumar Devireddy

Venkateshwar Rao Pullela

Bhushan Mangesh Kanekar

Hugh Holbrook

Peram Marimuthu

Stewart Frederick Bryant

Shyamsundar Nandkishor Maniyar

Bangalore L Priyadarshan

Reverse path forwarding protection of packets is provided using automated population of access control lists based on a forwarding information base. One implementation identifies a lookup value by extracting one or more values including a source address from a packet. An access control list lookup operation is performed on an access control list based on the lookup value to identify a permit or a deny condition, the access control list including multiple access control list entries. The packet is processed based on the permit or the deny condition identified in by the access control list lookup operation, this processing the packet based on the permit condition includes performing a forwarding lookup operation on a representation of a forwarding information base to identify a location and forwarding the packet to the location. The access control list entries are automatically generated based on a forwarding information base.

Reverse path forwarding protection of packets using automated population of access control lists based on a forwarding information base

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.

Performing lookup operations on associative memory entries

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

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 blocks or sets of associative memory entries in determining a lookup result, and detecting and propagating error conditions. In one implementation, indications of which associative memory blocks to use and/or enable in a particular lookup operation are retrieved from one or more memories, such as that based on received a profile ID. In one implementation, which may or may not be in a cascaded configuration, one or more identified or received error conditions are propagated in such a manner as to identify a source of each error condition.

Performing lookup operations using associative memories optionally including selectively determining which associative memory blocks to use in identifying a result and possibly propagating error indications

Methods and apparatus are disclosed for mapping prefixes and/or values of a hierarchical space to other representations while maintaining the original hierarchy, which may be especially useful in conjunction with associative memories, such as binary and ternary content-addressable memories. In one implementation, a set of prefixes associated with a hierarchical space is received. A new representation of the set of prefixes is developed, such as by using a trie representation, with the new representation maintaining the original hierarchical relationship. This new representation may be an optimized representation selected to reduce or minimize the depth of the trie or some other cost. A set of new prefixes are generated along with a set of lookup values. During processing, a value, such as that included in a packet, is converted to one of the lookup values, which is used to generate a lookup word for use in matching against the new prefixes.

Method and apparatus for mapping prefixes and values of a hierarchical space to other representations

Methods and apparatus are disclosed for allocating and using range identifiers as input values to associative memories, especially binary content-addressable memories (CAMs) and ternary content-addressable memories (TCAMs). In one implementation, each of multiple non-overlapping intervals are identified with one of multiple unique identifiers. An indication of a mapping between the multiple non-overlapping intervals and the multiple unique identifiers is maintained. A particular unique identifier is determined from said multiple unique identifiers based on a value and said multiple non-overlapping intervals. A lookup operation is performed on an associative memory using the particular unique identifier to generate a result. One implementation uses a trie representation of a range tree of the intervals to derive the unique identifiers. Moreover, one implementation evaluates and selects among various possible trie representations, especially to determine identifiers such that a TCAM prefix may match multiple intervals corresponding to a desired range.

Method and apparatus for allocating and using range identifiers as input values to content-addressable memories

Growing community of inventors

Santa Clara, CA, United States of America

Priyank Ramesh Warkhede