Fast Packet Classification Using Bloom filters Author: Sarang Dharmapurikar, Haoyu Song, Jonathan Turner, John Lockwood Publisher: Architecture for networking and communications systems, Proceedings of the 2006 ACM/IEEE symposium Presenter: Yu-Ping Chiang Date: 2008/11/5

Outline Related Work  Naive Crossproduct Algorithm  Multi-subset Crossproduct Algorithm Nested Level Tuple Space Search (NLTSS) NLT Merging and Crossproduct (NLTMC) Performance  Memory Requirement  Throughput

Naive Crossproduct Algorithm Pseudo rule  A match for a prefix also match it’s shorter prefix.  Too much overhead.

Naive Crossproduct Algorithm

Multi-subset Crossproduct Algo.

Outline Related Work  Naive Crossproduct Algorithm  Multi-subset Crossproduct Algorithm Nested Level Tuple Space Search (NLTSS) NLT Merging and Crossproduct (NLTMC) Performance  Memory Requirement  Throughput

Nested Level Tuple Space Search Definition:  Nested Level: # of marked ancestors of a marked node. Always assume root is marked

Nested Level Tuple Space Search Definition:  Nested Level Trie: remove unmarked nodes connecting marked node to nearest ancestor

Nested Level Tuple Space Search Definition:  Nested Level Tuple (NLT):

Do not need crossproduct rules. Number of NLTs is number of subsets. Nested Level Tuple Space Search

Definition:  NLT bitmap Set if prefix or it’s sub-prefix belongs to a rule contained in this NLT.  PL/NL bit-map 32 bits Set at a position indicates that the prefix of corresponding length is in the rule set.

Nested Level Tuple Space Search

Outline Related Work  Naive Crossproduct Algorithm  Multi-subset Crossproduct Algorithm Nested Level Tuple Space Search (NLTSS) NLT Merging and Crossproduct (NLTMC) Performance  Memory Requirement  Throughput

NLT Merging and Crossproduct Bounded set numbers Algorithm  Sort NLTs by the number of rules in them.  Pick most dense g NLTs. (g is limit # of subsets.)  Merge remaining NTL (rules) with one of fixed g NTLs. Choose “closest” NLT Ex: distance of [4,3,1,2,1] and [4,1,0,2,1] = |3-1| + |1-0| = 3  If there’s a pseudo-rule threshold, try to insert rule. If exceeds threshold, don’t insert it.

Outline Related Work  Naive Crossproduct Algorithm  Multi-subset Crossproduct Algorithm Nested Level Tuple Space Search (NLTSS) NLT Merging and Crossproduct (NLTMC) Performance  Memory Requirement  Throughput

On-chip bits per rule: .  For NLTSS, Off-chip bits per item: .  For NLTSS, Average memory consumption  NLTSS: 32 bytes  NLTMCL: 45 bytes Memory Requirement

Throughput Pipeline  1st stage: LPM  2nd stage: rule lookup. .. Clock rate LPM stage,144 bits/rule, Burst length: 72 bits Rule lookup stage