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FIB Aggregation with SMALTA

FIB Aggregation with SMALTA. Zartash Uzmi Ahsan Tariq Paul Francis draft-uzmi-smalta-00. FIB Aggregation Work. Normal Operation. Introduced at IETF 76 draft-zhang-fibaggregation Level 1-4 SMALTA == Level 5 Better aggregation No extra-routable space Comparable update processing

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FIB Aggregation with SMALTA

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  1. FIB Aggregation with SMALTA Zartash Uzmi Ahsan Tariq Paul Francis draft-uzmi-smalta-00

  2. FIB Aggregation Work Normal Operation • Introduced at IETF 76 • draft-zhang-fibaggregation • Level 1-4 • SMALTA == Level 5 • Better aggregation • No extra-routable space • Comparable update processing • For community information RIB Primary Routes FIB With Aggregation Original Table Aggregated Table FIB FIB Aggregation with SMALTA

  3. Comparative Summary *1 From various RIB snapshots (from routeviews) since 2004 FIB Aggregation with SMALTA

  4. FIB Aggregation: basic idea Aggregated Table Original Table /22 /22 Level 1 Specifics Removed A A /23 A /22 Level 2 Specifics Combines (beyond L1) A /23 /23 A A Exploit aggregation opportunities over entire Table FIB Aggregation with SMALTA

  5. Where does SMALTA stand? RIB snapshot  Aggregate  FIB: One-shot Algo BGP updates  Aggregated table: Update Algo FIB Aggregation with SMALTA

  6. One-shot and WITHDRAW Original Aggregated (SMALTA) C C With Level 1-4 Can’t aggregate any further! • Deaggregation • Opportunities to • aggregate more A B A A A A B Withdraw Withdraw C C A B A B B FIB Aggregation with SMALTA

  7. SMALTA Update 1. How far aggregated you are after N updates? After applying a full-day update trace: SMALTA loses between 1-6% of fully-aggregated state (one-shot) Measured for numerous routing tables across different years! 2. How many RIB-to-FIB downloads per update? Each update may result in just ONE change in Original Table RIB-to-FIB downloads: Exactly 1 (No Aggregation) 0/1/more (With Aggregation) FIB Aggregation with SMALTA

  8. Remarks • SMALTA One-Shot (300-400ms) ~3-4x more processing than L1 and L2 Applied very infrequently • SMALTA Update ~ same processing time as L1 and L2 Fewer avg. RIB-to-FIB downloads FIB Aggregation with SMALTA

  9. Comments / Questions

  10. Backup Slides

  11. Withdraw Withdraw Basic Idea for Updates Example 2: Aggregate specifics [having same next hop] – Level2 /22 A /23 /23 A A A FIB Aggregation with SMALTA

  12. One-shot + ANNOUNCE + WITHDRAW Original Aggregated (with SMALTA) C C A B A Announce(Q) A B Announce(Q) C C A B A A Q What if? Withdraw B Q FIB Aggregation with SMALTA

  13. Incremental Updates: Analysis • How far aggregated you are after N updates? • How long does it take to incorporate updates? • How many RIB to FIB downloads per update? FIB Aggregation with SMALTA

  14. Practicalities • Can’t aggregate entire table on every update • One-shot aggregation • Take current snapshot of RIB and Aggregate • On “significant” routing changes (e.g., BGP hard reset) • Perform a monolithic download after one-shot • To reflect BGP updates in FIB • Incremental updates to aggregated table FIB Aggregation with SMALTA

  15. Status: FIB Aggregation Work • Problem well-understood in GROW • draft-zhang-fibaggregation With Aggregation Normal Operation RIB Primary Routes Original Table [RIB] Aggregated Table Routing Updates Routing Updates IGP IGP FIB FIB FIB Aggregation with SMALTA

  16. SMALTA One-shot1,2 (no policy) Average Size  66% 44% 34% (of original) • Tables from a routeviews “collection” router [41-46 peers] • Policy (for best path): shortest AS path length preferred FIB Aggregation with SMALTA

  17. SMALTA Update: time consumed How long*3 does it take to incorporate an update? *3 Dependent on Platform and implementation (reportedfor comparison only) FIB Aggregation with SMALTA

  18. SMALTA: RIB to FIB Downloads(15-min update trace) *1 From a 15-minute update trace FIB Aggregation with SMALTA

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