Author ： Hyesook Lim, Changhoon Yim, and

Earl E. Swartzlander, Jr., Fellow

Publisher ： IEEE TRANSACTIONS ON COMPUTERS, VOL. 59, NO. 6, JUNE 2010

Presenter ： Yu-To Chen

Date ： 2011/09/21

Priority Tries for IP Address Lookup

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INTRODUCTIONTHE PROPOSED ALGORITHM

range representation of prefixespriority tries

PERFORMACE ANALYSIS AND SIMULATION

Outline

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In this range representation, prefixes are represented as ranges on a number line between 0 and 1 without expanding to the maximum length

The priority trie is based on the trie structure, with empty internal nodes in the trie replaced by the priority prefix which is the longest among those in the subtrie rooted by the empty nodes.

Introduction

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The prefix can be represented as a half-open range : range(prefix)=[lower bound , upper bound) 其中 ,

為 prefix length

range inclusion problem.

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Insert 規則1. 先將 prefix 排序由

長到短排序 ( 等長度隨機 )

2. 從 root 開始放 , 最長的放 root( 第 0 層 ),之後的由第一個位元開始依照 0 或 1 往左右走 ,遇到空的點或是該點為priority nood( 白點 )且 prefix 被自己包含即放入 , 並設為 priority nood

3. 若是層級剛好等於prefix 長度 , 則設為ordinary nood ( 黑點 ) 並佔據那一格

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Insert prefix : 1001101*

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Delete node : 10011*

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The entry width of the routing table can be designed with 39 bits (1 bit for the node identity, i.e., priority node or ordinary node, 25 bits for the prefix considering that the shortest prefix length is 8 bits, 5 bits for the prefix length, and 8 bits for routing information) plus two fields for child pointers.

The number of bits for the child pointers depends on the size of routing data set.

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