Multiprefix Trie: A New Data Structure for Designing Dynamic Router-Tables Author: Sun-Yuan Hsieh, Senior Member, IEEE, Yi-Ling Huang, and Ying-Chi Yang Publisher: IEEE TRANSACTIONS ON COMPUTERS 2011 Presenter: Yu Hao, Tseng Date: 2013/05/01 1

Outline Introduction Prefix Trees Multiprefix Trie Algorithm Index Multiprefix Trie Experimental Results Conclusion 2

Introduction One key feature of our data structure is that each node can store more than one prefix, which reduces the number of memory accesses. 3

Prefix Trees 4

Multiprefix Trie A k-stride Multiprefix Trie (k-MPT), where k is the stride which is a positive integer, contains two types of nodes, a primary node (p-node) and a secondary node (s-node). 5

Multiprefix Trie (Cont.) 6

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Multiprefix Trie (Cont.) 11

Multiprefix Trie (Cont.) An internal p-node is a full p-node. (ex : a and e.) An external p-node is a nonfull p-node. (ex : b, c, d and f.) 12

Multiprefix Trie (Cont.) 13

Multiprefix Trie (Cont.) 14

Algorithm Creating an Empty k-MPT 15 Algorithm MPT_CREATE(T) 1: v := ALLOCATE_P-NODE() 2: root(T) := v

Algorithm (Cont.) 16

Algorithm (Cont.) Insertion Operation Example 1. To insert the prefix 010* into a 2-MPT with m = 5. 17

Algorithm (Cont.) Insertion Operation Example 2. To insert the prefix * into a 2-MPT with m = 5. 18

Algorithm (Cont.) Insertion Operation 19

Algorithm (Cont.) Lookup Operation Ex 1. DA = Ex 2. DA =

Algorithm (Cont.) Delete Operation Example 1. To delete the prefix 01* from the 2-MPT with m = 5. 21

Algorithm (Cont.) Delete Operation Example 2. To delete the prefix * from the 2-MPT with m = 5. 22

Algorithm (Cont.) Delete Operation Example 2. To delete the prefix * from the 2-MPT with m = 5. 23

Algorithm (Cont.) Delete Operation 24

Index Multiprefix Trie 25

Index Multiprefix Trie (Cont.) 26

Experimental Results 27

Experimental Results (Cont.) 28

Experimental Results (Cont.) 29

Experimental Results (Cont.) 30

Conclusion We have proposed two new data structures, MPT and IMPT, for dynamic router-table design. Since the structures do not contain dummy nodes, they require less storage and they are not as high as other trees. In addition, because of the lower height, they require fewer memory accesses for router-table operations. 31