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MPLS Local Restoration using Optimized Aggregate Information

MPLS Local Restoration using Optimized Aggregate Information. Zartash Afzal Uzmi Computer Science and Engineering Lahore University of Management Sciences. Outline. Introduction QoS Requirements Local Restoration: Types of Backup Paths Local Restoration: Fault Models

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MPLS Local Restoration using Optimized Aggregate Information

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  1. MPLS Local Restoration using Optimized Aggregate Information Zartash Afzal Uzmi Computer Science and Engineering Lahore University of Management Sciences

  2. Outline • Introduction • QoS Requirements • Local Restoration: Types of Backup Paths • Local Restoration: Fault Models • Backup Bandwidth Sharing • Activation sets • The new model for bandwidth sharing • Optimized aggregate information scenario (oAIS) • Experiments, simulations, and results Lahore University of Management Sciences

  3. QoS Requirements • Bandwidth Guaranteed Primary Paths • Bandwidth Guaranteed Backup Paths • BW remains provisioned in case of network failure • Minimal “Restoration Latency” • Restoration latency is the time that elapses between the occurrence of a failure and the diversion of network traffic on a new path Path Restoration  More Latency Local Restoration  Less Latency Lahore University of Management Sciences

  4. Types of Backup Paths • A next hop (nhop) path that spans a link (i, j) is a backup path which: • originates at node i, and • provides restoration for a primary LSP that traverses (i, j), if (i, j) fails. i j nhop path that spans (i, j) PLR: Point of Local Repair Lahore University of Management Sciences

  5. Types of Backup Paths • A next next hop (nnhop) path that spans a link (i, j) is a backup path which: • originates at node i, and • provides restoration for a primary LSP that traverses (i, j), if either (i, j) or node j fails. nnhop path that spans (i, j) j i PLR: Point of Local Repair Lahore University of Management Sciences

  6. A B C D Local Restoration: Fault Models Link Protection Node Protection A B C D Element Protection A B C D Lahore University of Management Sciences

  7. Primary Path Backup Path nhop and nnhop paths nnhop A B D C E nhop PLR: Point of Local Repair All links and all nodes are protected! Lahore University of Management Sciences

  8. Opportunity cost of backup paths • Local Protection requires that backup paths are setup in advance • Upon failure, traffic is promptly switched onto preset backup paths • Bandwidth must be reserved for all backup paths • This results in a reduction in the number of Primary LSPs that can otherwise be placed on the network • Can we reduce the amount of “backup bandwidth” but still provide guaranteed backups? Lahore University of Management Sciences

  9. Sharing Primary Path Backup Path BW Sharing in backup Paths • Example: L1 BW: X A B X X max(X, Y) X E G F X+Y Y Y C D L2 BW: Y Lahore University of Management Sciences

  10. Activation Sets A A E E B B C C D D Activation set for node B Activation set for link (A,B) Lahore University of Management Sciences

  11. Extent of BW Sharing: oAIS • Aggregate Information Scenario (AIS) • Fij: Bandwidth reserved on link (i, j) for all primary LSPs • Gij: Bandwidth reserved on link (i, j) for all backup LSPs • Optimized AIS (oAIS) – (Hij instead of Fij) • Hij: Maximum bandwidth reserved on any one link by all backup paths spanning link (i, j) More Information propagated  More potential for BW sharing Lahore University of Management Sciences

  12. oAIS versus AIS: Example LSP Request-1 (src, dst, bw) = (A, C, 4) D E F GAF=4 FAB=4 A B C HAB=4 G Lahore University of Management Sciences

  13. oAIS Example LSP Request-2 (src, dst, bw) = (A, C, 5) D E F GAF=4 FAB=9 FAB=4 A B C HAB=5 HAB=4 GAG=5 G Lahore University of Management Sciences

  14. oAIS Example LSP Request-3 (src, dst, bw) = (D, E, 7) FDE=7 D E F GAF=4 GAF=7 FAB=9 A B C HAB=5 GAG=5 G Lahore University of Management Sciences

  15. oAIS Example LSP Request-4 (src, dst, bw) = (A, C, 6) Need to Evaluate cost of all possible backup paths? FDE=7 How much BW is shareable on (A, F)? D E AIS: Shareable = max(0, GAF - FAB) = GAF - min(GAF, FAB) = 0 Additional resv = 6 F GAF=7 oAIS: (HAB≤ FAB) Shareable = GAF - min(GAF, HAB) = 2 Additional resv = 6 - 2 = 4 FAB=9 A B C HAB=5 CIS: (link (A,B) knows BWred) Shareable = GAF - BWred = 7 - 4 = 3 Additional resv = 6 - 3 = 3 GAG=5 G Lahore University of Management Sciences

  16. Bandwidth Sharing Model • Previous: • Aij:= Set of all primaries traversing through (i, j) • Bij:= Set of all backups traversing through (u, v) • Our definition (for link protection case): • Aij:= Set of all primaries traversing through (i, j) • Bij:= Set of all nhop paths traversing through (u, v) • µij:= Set of all nhop paths that span (i, j) • ijuv:= Buv ∩ µij Lahore University of Management Sciences

  17. Bandwidth Sharing Model RED=7 BLU=2 u v GRN=3 (New Request) Guv = 10 3 k i j NEW MODEL: Aij = {R, B} Buv = {nhijr, nhijb, …} (nhops through (u, v)) µij = {nhijr, nhijb, …} (nhops spanning (i, j)) ijuv = µij ∩ Buv= {nhijr} || ijuv || = 2 + 7 = 9 (Un-shareable) Shareable = Guv - || ijuv || = 10 - 9 = 1 OLD MODEL: Aij = {R, B} Buv = {R, B, …} Aij ∩ Buv= {R, B} || Aij ∩ Buv || = 2+7 = 9 Un-shareable = 9 Shareable = 10 - 9 = 1 Lahore University of Management Sciences

  18. Bandwidth Sharing Model RED=7 BLU=2 u v GRN=3 (New Request) Guv = 10 3 k i j OLD MODEL: Aij = {R, B} Buv = {R, B, …} Aij ∩ Buv= {R, B} || Aij ∩ Buv || = 2+7 = 9 Un-shareable = 9 Shareable = 10 - 9 = 1 NEW MODEL: Aij = {R, B} Buv = {nhijr, nhjkb, …} (nhops through (u, v)) µij = {nhijr, nhijb, …} (nhops spanning (i, j)) ijuv = µij ∩ Buv= {nhijr} || ijuv || = 7 (Un-shareable) Shareable = Guv - || ijuv || = 10 - 7 = 3 Lahore University of Management Sciences

  19. Simulation Experiments • Rejected Requests Experiments • Simulated on two topologies • Measure the number of rejected LSPs for each information scenario • Network Loading Experiments • Simulated on two topologies • Link capacities set to infinity • Measure the total bandwidth required to service a given set of LSPs for each information scenario Lahore University of Management Sciences

  20. Single Link Protection: Network 1 Lahore University of Management Sciences

  21. Single Link Protection: Network 1 Lahore University of Management Sciences

  22. Single Link Protection: Network 2 Lahore University of Management Sciences

  23. Single Link Protection: Network 2 Lahore University of Management Sciences

  24. Single Node Protection: Network 1 Lahore University of Management Sciences

  25. Single Element Protection: Network 1 Lahore University of Management Sciences

  26. Questions & Answers Lahore University of Management Sciences

  27. Restoration in MPLS Path Protection A B C D E MPLS path Protection may take 100s of ms, whereas MPLS Local protection takes less than 10 ms. Primary Path Backup Path Lahore University of Management Sciences

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