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MULTILAYER SURVIVABILITY Keerthana Boloor Raghu Kalyan Anna

MULTILAYER SURVIVABILITY Keerthana Boloor Raghu Kalyan Anna. 1. AGENDA Motivation Multilayer survivability models Common pool Survivability Dynamic multilayer resilience schemes References. MOTIVATION. Integrated solution for survivability.

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MULTILAYER SURVIVABILITY Keerthana Boloor Raghu Kalyan Anna

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  1. MULTILAYER SURVIVABILITY Keerthana Boloor Raghu Kalyan Anna 1

  2. AGENDA Motivation Multilayer survivability models Common pool Survivability Dynamic multilayer resilience schemes References

  3. MOTIVATION Integrated solution for survivability

  4. Avoiding contention between different single layer recovery schemes. Sharing capacity. (Prevent double protection) Increased overall ability of the existing infrastructure and reducing costs for certain survivability target. Project PANEL – University of Gent, Belgium.

  5. MULTILAYER SURVIVABILITY MODELS PANEL Framework

  6. Drivers for recovery at multiple layers: • Recovery at lower layers is efficient for cable cuts – bulk recovery • Recovery at higher layers is required for equipment failure • Recovery is required at layer where traffic was injected into the network for differentiation of service reliability

  7. RECOVERY AT LOWEST LAYER Recovery provided as close as possible to the layer of the failure origin.

  8. Interworking functionality required (Co-ordination of “alarm” signals – hold-off timer and recovery ratio [recovery token signal]) Spare capacity required in all layers

  9. RECOVERY AT HIGHEST LAYER Recovery at layer closer to the origin of the traffic

  10. Easier to provide multiple reliability grades Interworking complexity between multiple layers can be avoided. Slower recovery process due to finer granularity of recovery possible requirement of reconfiguration of network elements far from the source of failure Not efficient for hybrid networks.

  11. COMPARISON Average Recovery at lowest layer with hold-off timer : 250 ms Average recovery at highest layer (low loads) : 900 ms

  12. RECOVERY INTERWORKING / ESCALATION Set of rules to determine the instant of activation and termination of the activities of the different recovery schemes. Parallel activation Takes shorter recovery times but is difficult to control and is not implemented in the papers considered. Sequential activation Bottom up approach Top Down approach

  13. COMMON POOL SURVIVABILITY Multilayer survivability implies multiple spare capacity pools separately in each layer. Traditional planning approaches result in poor utilization of lower layer approaches because the server spare layers are protected in the client layers – redundant or double protection Improvements: Leave spare client resources unprotected in server layers Common pool

  14. Treat spare capacity of the client layer as unprotected preemptible traffic in the server layer

  15. EXPERIMENTAL RESULTS

  16. Spare Capacity of the ATM layer is treated as extra traffic in SDH layer The spare capacity of the SDH layer is reused for extra resilience at the ATM layer. Most effective in hybrid ATM and SDH networks. A simultaneous breakdown of the ATM equipment and an SDH cable cut cannot be survived by this approach. This kind of failure is considered to be extremely rare by the authors and effect of service availability is very low. Savings due to common pool survivability is substantial.

  17. CAPACITY REQUIREMENTS

  18. DYNAMIC MULTILAYER RESILIENCE The logical client topology is reconfigured during failure conditions. No longer a requirement for spare capacity in the IP layer Spare capacity in the lower layers for cable cuts and OXC failures required. Dynamic client layer dimensioning is carried out. Global configuration : Have an optimal topology with respect to new traffic pattern Local configuration: Reroute on the reduced topology.

  19. INTRODUCTION Increase in IP traffic growth -> network reliability Need of the hour: IP/MPLS over OTN than traditional IP/ATM/SDH over OTN MPLS introduction allows enhancement of network capabilities – TE and/or QoS

  20. INTRODUCTION (1) IP traffic – volume ( ), pattern ( ) Permanent connections established through NMS are not optimized for these IP traffic. ION – Intelligent Optical Network GMPLS – extension of MPLS concept, labels are now represented by ‘λ’ (WDM) or time slot (TDM) UNI in ASONs (Automatic Switched Optical Network ) provides switched connection services ION – ASON/GMPLS capable optical network

  21. ASON slide adopted from Dr. Raj Jain’s Optical Networks Lecture, Washington University

  22. NETWORK SURVIVABILITY Using WDM a single fiber can carry 160 or more Wavelengths Each fiber can carry up to 10 Giga Bit (Gb/s)  40 Gb/s Single cable cut can influence Tera Bit (Tb/s) of data Network Survivability : Ability of the network to recover traffic affected by failures:

  23. MULTILAYER RESILIENCE Multilayer IP-over-OTN network

  24. MULTILAYER RESILIENCE (2) Implications: If OXC D fails then OTN can recover the traffic on IP/MPLS primary path 1 using optical recovery path 1 OTN cannot restore the traffic from IP/MPLS primary path 2

  25. MULTILAYER RESILIENCE (3) • Deploy recovery schemes in both layers of the network to ensure survivability of at least single root failure • Network recovery in a IP/MPLS-over-OTN scenario: • for IP/MPLS layer eg:- MPLS rerouting, Fast Topology-Driven Constraint-Based Rerouting (FTCR), and MPLS Local protection • for OTN layer eg:- Path or Link restoration, 1+1 Path protection, or 1:1 path protection

  26. MULTILAYER RESILIENCE (4) • Deployment challenges: • Inter working functionality • Spare capacity: Static transport network Vs Intelligent transport network (ION)

  27. STATIC MULTILAYER RESILIENCE (1) • Spare Capacity needed in both IP/MPLS and OTN layers. • How is IP/MPLS spare capacity is provided by OTN layer? • Double or Redundant protection • IP spare not protected • Common pool

  28. STATIC MULTILAYER RESILIENCE (2) Logical IP topology Optical Level Static Multilayer Resilience Scheme

  29. DYNAMICMULTILAYER RESILIENCE ION, Any flexibility? IP layer dimensioning: nominal and one for each IP router failure scenario N -> N + 1 worst case requirements

  30. DYNAMICMULTILAYER RESILIENCE (1) Failure-free scenario Single IP failure scenarios

  31. DYNAMICMULTILAYER RESILIENCE (1) Static Resilience scheme Dynamic Resilience scheme OTN layer requirements

  32. DYNAMICMULTILAYER RESILIENCE (2) IP topology reconfiguration schemes: ION global reconfiguration ION local reconfiguration

  33. DYNAMIC Vs STATIC RESILIENCE SCHEMES IP over optical network provided by IST LION project Logical IP topology optimized for failure-free scenario Optical layer: 14 OXCs, 28 links, biconnected mesh topology Logical IP layer: 14 routers Asymmetric traffic pattern: VoIP, email, Web browsing, FTP

  34. DYNAMIC Vs STATIC RESILIENCE SCHEMES ISO LION project: OTN layer Topology

  35. DYNAMIC Vs STATIC RESILIENCE SCHEMES ISO LION project: IP layer Topology

  36. DYNAMIC Vs STATIC RESILIENCE SCHEMES (1) Network cost is split into 3 costs: Line, Node, Tributary Cost Comparison

  37. DYNAMIC Vs STATIC RESILIENCE SCHEMES (2) Implications of Cost Analysis: ION local reconfiguration is cost efficient What can be said about Dynamic schemes? Why common pool is not least expensive?

  38. DYNAMIC Vs STATIC RESILIENCE SCHEMES Relative number staying Relative number setup ION Global Reconfiguration scheme

  39. DYNAMIC Vs STATIC RESILIENCE SCHEMES Relative number staying Relative number setup ION Local Reconfiguration scheme

  40. DYNAMIC Vs STATIC RESILIENCE SCHEMES • Operational aspects? • In static reconfiguration not required since it is static • Using ION flexibility in dynamic schemes, logical IP topology is reconfigured. • reconfigurations: number of actions for setting up or tearing down a light path • ION global reconfiguration Vs ION local reconfiguration

  41. DYNAMIC Vs STATIC RESILIENCE SCHEMES Failure types relative to IP router: local link, semi-local link, and non-local link IP link reconfiguration

  42. DYNAMIC Vs STATIC RESILIENCE SCHEMES Implication: In ION local reconfiguration scheme almost all those lightpaths can be set up by a router which detects that its immediate neighbor is no longer reachable

  43. CONCLUSION STATIC Vs DYNAMIC RESILIENCE SCHEMES ION Local reconfiguration is an attractive solution ION Global reconfiguration is more expensive than Double protection static scheme

  44. ACKNOWLEDGEMENT • FIGURES HAVE BEEN ADOPTED FROM: • 1. Resilience in Multilayer Networks, Piet Demeester, Carlo Brianza • 2. Intelligent Optical Networking for Multilayer Survivability, Didier Colle, Piet Demeester • 3. PANEL – Protection Across Network Layers, Piet Demeester, Carlo Brianza • 4. Common Pool survivability for meshed SDH-based ATM networks, Piet Demeester, Mario Pickavet • 5.http://www.cse.wustl.edu/~jain/tutorials/t_6ipwd.htm • 6.http://farm2.static.flickr.com/1245/616310509_02202b17b7.jpg

  45. REFERENCES • 1. Resilience in Multilayer Networks, Piet Demeester, Carlo Brianza • 2. Intelligent Optical Networking for Multilayer Survivability, Didier Colle, Piet Demeester • 3. PANEL – Protection Across Network Layers, Piet Demeester, Carlo Brianza • 4. Common Pool survivability for meshed SDH-based ATM networks, Piet Demeester, Mario Pickavet

  46. QUERIES ?

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