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The NPP++ Framework for Protection Routing in MPLS

The NPP++ Framework for Protection Routing in MPLS. Zartash Afzal Uzmi Computer Science and Engineering Lahore University of Management Sciences (LUMS) Pakistan. Outline. Background and Preview IP and MPLS Routing Protection Routing in MPLS Backup Bandwidth Sharing

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The NPP++ Framework for Protection Routing in MPLS

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  1. The NPP++ Framework forProtection Routing in MPLS Zartash Afzal Uzmi Computer Science and Engineering Lahore University of Management Sciences (LUMS) Pakistan

  2. Outline • Background and Preview • IP and MPLS Routing • Protection Routing in MPLS • Backup Bandwidth Sharing • Sharing with Primary Paths • NPP++ Protection Routing Framework • Routing Overhead • Path Computation • Path Signaling • Simulation Results • Evaluation and Experimentation • Simulation Parameters • Comparative Results

  3. Outline • Background and Preview • IP and MPLS Routing • Protection Routing in MPLS • Backup Bandwidth Sharing • Sharing with Primary Paths • NPP++ Protection Routing Framework • Routing Overhead • Path Computation • Path Signaling • Simulation Results • Evaluation and Experimentation • Simulation Parameters • Comparative Results

  4. IP versus MPLS Routing • IP Routing • Destination-based • Hop-by-hop • MPLS Routing: • An MPLS path or “virtual circuit” from source to destination (ingress to egress) A label switched path (LSP) is pre-established

  5. 31 D 17 D 11 D MPLS Flow Progress destination D ingress D R1 LSR4 R2 LSR1 D S source LSR6 egress LSR3 LSR2 LSR5 LSP

  6. Protection Routing with MPLS • Bandwidth Guaranteed Primary Paths • Bandwidth Guaranteed Backup Paths • BW remains provisioned in case of a failure • Minimal “Recovery Latency” Need Preset backup paths with Local Protection

  7. Primary Path Backup Path Types of Backup Paths LOCAL PROTECTION of one primary path from A to E nnhop A B D C E nhop PLR: Point of Local Repair All links and all nodes are protected!

  8. Opportunity cost of backup paths • Backup paths are setup in advance • Upon failure, traffic is promptly switched onto preset backup paths • Bandwidth must be reserved for all backup paths • Reduced number of Primary LSPs (that can otherwise be placed) • Can we reduce the amount of “backup bandwidth”? • YES: Try to share the bandwidth along backup paths

  9. Primary Path Backup Path BW Sharing in backup Paths • Example: LSP1 BW: X Sharing is possible IF Links (A,B) and (C,D) do not simultaneously fail! A B X X max(X, Y) X E G F X+Y Y Y C D BW: Y LSP2

  10. Activation Sets A A E E B B C C D D Activation set for node B Activation set for link (A,B) Paths in the same activation set MUST not share bandwidth

  11. Sharing with Primary Paths • Can we do any sharing with primary paths? • Normally, the answer is NO because… • Traffic is always flowing on the primary paths • BUT… • Backup paths protecting a node N may share bandwidth with primary paths that originate or terminate at node N because… • Such backup will be active when: • node N fails, and in that condition… • No primary originates or terminates at node N Sharing with (some) primary paths is possible

  12. Outline • Background and Preview • IP and MPLS Routing • Protection Routing in MPLS • Backup Bandwidth Sharing • Sharing with Primary Paths • NPP++ Protection Routing Framework • Routing Overhead • Path Computation • Path Signaling • Simulation Results • Evaluation and Experimentation • Simulation Parameters • Comparative Results

  13. Protection Routing Framework • Tasks of a protection routing framework: • Path computation • Path signaling and setup • Objectives of a protection routing framework 1. Incur scalable routing overhead 2. Find optimal primary paths 3. Find optimal backup paths 4. Maximize bandwidth sharing • NPP++ framework achieves all of above • However, (2) and (3) are not achieved jointly Primary and Backup   

  14. 1.Scalable routing overhead • 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 • Rij: Bandwidth remaining on link (i, j) • NPP++ relies on AIS • Low routing overhead More Information propagated  More potential for BW sharing

  15. 2.Optimal backup paths • Who computes the backup paths? • Node that computes backup paths maintains two local maps: • BFTLIM • How much backup bandwidth will fall on a given link (u,v) if this element fails • PFTLIM • How much primary bandwidth will be available on a given link (u,v) if this element fails • FTLIMs keep historical information about bandwidth reserved for protecting an element • Leads to the computation of backup paths that are optimal

  16. Path Computation in NPP++ R2 Contains: a) BFTLIM b) PFTLIM GOAL: Find a backup path that protects R2 R1 R5 R2 R3 R4 Path computation is shifted to R2 because… Only R2 has full knowledge of its own Activation set

  17. 3.Maximum Bandwidth Sharing • Optimal path is signaled with requirements for FULL bandwidth • All nodes (along the backup path) maintain two local data structures: • BLTFIM • How much backup bandwidth will fall on this link if a given element fails • PLTFIM • How much primary bandwidth will be released on this link if a given element fails • LTFIMs help nodes reserve only what is needed • Leading to maximum sharing along backup paths

  18. NPP++ Summary Protecting R2 (1) Advertise aggregate link usage information only LTFIMs R4 R1 R2 R3 FTLIMs FTLIMs FTLIMs LTFIMs LTFIMs (2) Path computation is shifted to special nodes • Results: • Path computation is optimal • Bandwidth sharing on backup paths is maximum. • Advertisement overhead is minimum (3) Nodes in primary path maintain “local data structures” called BFTLIM/PFTLIM Primary Path (4) Nodes in backup paths maintain “local data structures” called BLTFIM/PLTFIM Backup Path

  19. Outline • Background and Preview • IP and MPLS Routing • Protection Routing in MPLS • Backup Bandwidth Sharing • Sharing with Primary Paths • NPP++ Protection Routing Framework • Routing Overhead • Path Computation • Path Signaling • Simulation Results • Evaluation and Experimentation • Simulation Parameters • Comparative Results

  20. Evaluation & Experimentation • Traffic generation • Used existing traffic models • Rejected requests experiments • Generate a set of LSP requests • Measure the number of rejected requests • Simulate on various topologies • Scalability of local state information • How do the average number of entries in locally stored maps grow with the number of requests

  21. Simulation Parameters • Simulations performed on two networks • Network 1: • 15-node heterogeneous topology • Core links with capacity 480 units, other links 120 units • Network 2: • 20-node homogenous topology (metros in the U.S.) • Each link with capacity 120 units • LSP requests arrive one-by-one • Ingress/Egress pairs chosen randomly • Bandwidth demand for each request is uniformly distributed between 1 and 6 • 100 experiments with different traffic matrices

  22. Comparative Results: Network 1

  23. Comparative Results: Network 2

  24. Local Storage: Network 1

  25. Local Storage: Network 2

  26. Conclusions: NPP++ • Optimal path computation • Maximum sharing along computed path • With backup paths and with primary paths • Scalable routing overhead • Practically feasible • 15% – 40% improvement over existing protection schemes

  27. Last slide… Thank you! Questions?

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