On the design of LPM address generators using multiple LUT Cascades on FPGAs
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Authors
Qin, Hui
Sasao, Tsutomu
Butler, Jon T.
Subjects
LPM address generator
Multiple LUT cascade
FPGA
Multiple LUT cascade
FPGA
Advisors
Date of Issue
2007-05
Date
May 2007
Publisher
Language
Abstract
We propose the multiple LUT cascade as a means to configure an n-input LPM (Longest Prefix
Match) address generator commonly used in routers to determine the output port given an address.
The LPM address generator accepts n-bit addresses which it matches against k stored prefixes.
We implement our design on a Xilinx Spartan-3 FPGA for n = 32 and k = 504 ∼ 511. Also, we
compare our design to a Xilinx proprietary TCAM (ternary content-addressable memory) design and
to another design we propose as a likely solution to this problem. Our best multiple LUT cascade
implementation has 5.17 times more throughput, 40.71 times more throughput/area and is 2.97 times
more efficient in terms of area-delay product than Xilinx’s proprietary design, but its area is only
15% of Xilinx’s design. Furthermore, we derive a method to determine the optimum configuration of
the multiple LUT cascade on an FPGA.
Type
Article
Description
International Journal of Electronics, Vol. 94, Issue 5, May 2007, pp.451-467,
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted.
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted.
Series/Report No
Department
Department of Electrical and Computer Engineering
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NPS Report Number
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Citation
H. Qin, T. Sasao, and J. T. Butler, "On the design of LPM address generators using multiple LUT Cascades on FPGAs," International Journal of Electronics, Vol. 94, Issue 5, May 2007, pp.451-467,