MULTI-WAY PIPELINING FOR POWER-EFfiCIENT IP LOOKUP

1. MULTI-WAY PIPELINING FOR POWER-EFfiCIENT IP LOOKUP Author: Weirong Jiang and Viktor K. Prasanna Publisher/Conf.: IEEE GLOBECOM 2008 Speaker: Han-Jhen Guo Date: 2008.12.17

2. OUTLINE • Background and Related Work • Proposed Scheme • introduction of proposed scheme • hybrid SRAM/TCAM-based partitioning • fine-grained node-to-stage mapping • Performance

3. BACKGROUND AND RELATED WORK • Uni-bit trie Leaf pushing

4. Proposed Scheme- Introduction Of Proposed Scheme • Multi-way linear pipeline architecture (P=4) • each pipeline stores a portion of the routing table • hybrid SRAM/TCAM-based partitioning scheme • ensure that pipelines contain exactly equal numbers of trie nodes • fine-grained node-to-stage mapping scheme within each pipeline • balance the memory distribution over pipeline stages

5. Proposed Scheme- Hybrid SRAM/TCAM-based Partitioning • Prefix expansion • initial stride larger, • smaller subtries → can help balance the memory distribution across stages when mapping nodes to stages within a pipeline • more prefix duplication (a prefix may be copied to multiple subtries) initial stride (I)

6. Proposed Scheme- Hybrid SRAM/TCAM-based Partitioning • Post-order split • ensures that each pipeline contains ceiling of (total nodes of subtries / number of pipelines) nodes (except the last one pipeline) • sort the subtries obtained after prefix expansion in decreasing order of size ceiling of (3+11+1+3) / 2

7. Proposed Scheme- hybrid SRAM/TCAM-based partitioning • Index table implementation priority(SRAM_B) > priority(SRAM_A) remaining subtries based on I

8. Proposed Scheme- fine-grained node-to-stage mapping • Leaf reduction after leaf reduction subtries in pipeline 1

9. Proposed Scheme- fine-grained node-to-stage mapping • Eg. of node-to-stage mapping with pipeline 1

10. Proposed Scheme- hybrid SRAM/TCAM-based partitioning • Index table implementation address of the subtrie’s root in the 1st stage of pipeline 0 1 2

11. PERFORMANCE • Node distribution over 8 pipelines • results for 16 routing tables partitioning scheme achieved a balanced memory allocation among the eight pipelines

12. PERFORMANCE • Node distribution over 25 stages in the 8-way pipeline architecture there were few nodes at the top levels of any subtrie → unbalanced at first several stages each pipeline

13. Thanks for your listening!