A NOVEL LEVEL-BASED IPV6 ROUTING LOOKUP ALGORITHM Author: Xiaohong Huang, Xiaoyu Zhao, Guofeng Zhao, Wenjian Jiang, Dongqu Zheng, Qiong Sun and Yan Ma Publisher/Conf.: IEEE GLOBECOM 2008 Speaker: Han-Jhen Guo Date:

OUTLINE Introduction The Proposed Algorithm Performance Evaluation 2

INTRODUCTION IPv6 address allocation hierarchy 3 global unicast IPv6 addresses of /23 from “001*” /32 /48

INTRODUCTION IPv6 Prefix Length Distribution 6 IPv6 backbone BGP routing tables in the real world the number of routing entries in a routing table < lookup frequently lookup frequently default route default route mainly used mainly used secondly no prefixes no prefixes

INTRODUCTION Characteristics according to RFC3587, the first three bits of IPv6 unicast address should be constantly ‘001’→ needs no process lookup on 128 bits can be focused mainly on the 16th ~ 64th bits the values of word consisting of the 4rd ~16th bits are numerable lookup on the 17th ~ 32nd bits is very frequent lookup on the 33rd ~ 64th bits can take advantage of the hierarchy of prefixes lookup on the 65th ~128th bits can be processed separately 5

THE PROPOSED ALGORITHM - OUTLINE Level-based Routing Lookup (LRL) algorithm Data Structure 6 16 bits for each lv.

THE PROPOSED ALGORITHM - LEVEL 1 Level 1: Index Table first three bits = 001 → 2 (16-3) entries use 4 th ~ 16 th bits to index data structure of each entry 7

THE PROPOSED ALGORITHM - LEVEL 2 Level 2: Segment Table 2 16 entries use 17 th ~ 32 th bits to index data structure Max_MaskLength : length of the longest prefix whose prefix length is no longer than 32 and the value of the second word (17th ~ 32nd bits) is corresponding to this Segment Table entry CollidePointer : the length of prefixes which have the same second word-value but shorter than prefix of Length 8 use for “update”

THE PROPOSED ALGORITHM - LEVEL 3 Level 3: Prefix Hierarchical Trie (PHT) use 33 th ~ 64 th bits definition Sub-prefix if a prefix is covered by another one, we call the former a sub-prefix of the latter one ( descendent ) Direct sub-prefix if a prefix is directly covered by another one, we call the former a direct sub- prefix of the latter one ( direct descendent ) Brother-prefix all direct sub-prefixes of one same prefix 9

THE PROPOSED ALGORITHM - LEVEL 3 Construction a PHT 10 direct sub-prefixbrother-prefix

THE PROPOSED ALGORITHM - LEVEL 3 Searching on a PHT search the IP = * 000* 10* 0000*010* 0100* 011* 1010* 111* 1011*1010* return next-hop info. = 4

THE PROPOSED ALGORITHM - LEVEL 3 Insertion into a PHT insert a prefix = 101* 12 0* 000* 10* 0000*010* 0100* 011* 1010* 111* 1011*1010* len. of inserted prefix < searched prefix or a NULL ptr. is searched →stop and insert there *

THE PROPOSED ALGORITHM - LEVEL 4 Level 4: Bucket use 65 th ~ 128 th bits data structure depend on lookup approach (such as linear search, binary search, etc.) 13

PERFORMANCE EVALUATION Evaluation using real world IPv6 routing tables lookup performance comparison 14

PERFORMANCE EVALUATION Evaluation using real world IPv6 routing tables memory consumption 15

PERFORMANCE EVALUATION Evaluation using synthetically created IPv6 routing tables lookup performance comparison 16

PERFORMANCE EVALUATION Evaluation using synthetically created IPv6 routing tables memory consumption 17 stable than other schemes

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