A ternary content addressable search engine

Abstract

This paperdeseribes the design, implementation, and experimental results for a ternary content addressable search engine cfdp, known as the Database Accelerator (DBA). The DBA chip architecture is presented, and it is well suited to serve as a coprocessor for a variety of logical search applications. The core of the DBA system is composed of novel high-density content addressable memory (CAM) cells capable of storing three states. The design of these cells and their support circuitry is described. The CAM cell and support circuitry were fabricated and their operation confirmed. The circuit implementation of the DBA data path is described with particular emphasis on the optimization of the multiple response resolver. The timing and control methodology, which simultaneously satisfies the complexity, speed, and robustness requirements of the DBA chip, is reported. Fhally, experimental DBA chip results are presente@ these results verify the full functionality and testability of the design.

Coolcams: power-efficient TCAMs for forwarding engines

“…One of the earliest works to introduce ternary CAMs was by Wade and Sodini [12]-later, the authors proposed using TCAMs in a hardware search engine called a Database Accelerator [13]. The use of TCAMs for routing table lookups was first proposed by McAuley and Francis [7]; they also described the problem of updating TCAM-based routing tables that are sorted with respect to prefix lengths.…”

“…The second reason is that of high power consumption. Current high-density TCAM devices consume as much as [12][13][14][15] Watts each when all the entries are enabled for search. Moreover, a single linecard may require multiple TCAMs to handle filtering and classification as well as IP lookup on large forwarding tables.…”

Decoupled dynamic ternary content addressable memories

“…A CAM performs a parallel comparison of stored data with an input argument. These features have earned CAM's widespread usage which include: translation look-aside buffers for virtual memory systems, tag directories in fully associative cache organizations [1], collision detection VLSI processor for intelligent vehicles [2], interconnection network router [3], [4], database accelerator [5], self-testing reconfigurable CAM [6], and applications in artificial intelligence and image processing. Additional applications include logic inference, classifiers [7], [8], pattern matching [9], sorting [10], and applications that require searches in specific address ranges [11].…”

A keyword match processor architecture using content addressable memory

“…In applications that require fast search times, application specific hardware implementations have been introduced [13,8,10,14], and for the most part, these hardware implementations have included the use of content addressable memories (CAM). CAMs allow keyword matches to be done in a single cycle making search a constant time operation rather Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page.…”

“…The use of content addressable memories for text search has centered around two strategies: cellular automata [12,10,11] and finite state machines [14,7]. The cellular automata methods cascade CAMs temporally and then use pointers to propagate matches from one CAM set to another [9].…”