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WP2 UPC Contribution to A2.2.1: Route Management

WP2 UPC Contribution to A2.2.1: Route Management. Route management. Network models Packet-switched/wavelength-switched model Routing models / Route management models Static routing model(s) [ETH, UPC, all partners] Combined intra- and inter domain routing model(s) [ETH, UPC]

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WP2 UPC Contribution to A2.2.1: Route Management

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  1. WP2UPC Contribution to A2.2.1: Route Management NOBEL: Berlin May 18-19, 2004

  2. Route management • Network models • Packet-switched/wavelength-switched model • Routing models / Route management models • Static routing model(s) [ETH, UPC, all partners] • Combined intra- and inter domain routing model(s) [ETH, UPC] • Adaptive routing model(s) • Predictive routing model(s) • Multicast routing model NOBEL: Berlin May 18-19, 2004

  3. Optical Packet and Optical Burst vsWavelength Switched Model • Physical • Technological requirements – how advanced optical components are expected • Complexity of the hardware (node architecture) • Computational • Node control algorithms complexity • Routing algorithms complexity • Performance • Efficiency, network utilization • Flexibility • Data formats, bitrates, ... • Label switching paradigm – paths (connections) granularity, scalability NOBEL: Berlin May 18-19, 2004

  4. Optical Packet and Optical Burst vsWavelength Switched Model • QoS • Difficulty in quality guarantees • Hardware and control algorithms complexity • Network • Control Plane implementation • Signalization overhead • Adaptation to traffic demands • Interworking • With legacy networks – edge node operation complexity (adaptation, aggregation, ...) • Costs • Hardware (node), building of the network, ... NOBEL: Berlin May 18-19, 2004

  5. Physical – technological, hardware requirements Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  6. Computational complexity Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  7. Optical Packet and Optical Burst vsWavelength Switched Model Performance Network utilization, efficiency • Wavelength switching • Not dynamically adopted (in real time) to the actual traffic demands • Efficiency up to 9 times worse than in OBS/OPS, very high wavelength consumption • Medium blocking probability • Burst switching • Network utilization higher than at WS (due to statistical multiplexing in optical domain) • High blocking probability - optical buffers need for fine network performance • Packet switching • Very high network utilization (statistical multiplexing in optical domain) • Needs FDLs and WC’s for high performance (low PLR) • Even with FDLs, packet delay is low due to fast optical switching (without O/E conversion of packet payload) NOBEL: Berlin May 18-19, 2004

  8. Flexibility Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  9. QoS Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  10. Network aspects Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  11. Optical Packet and Optical Burst vsWavelength Switched Model Interworking With legacy networks,edge node operation complexity (adaptation, aggregation, ...) • Wavelength switching • Lack of aggregation problem • Adaptation only in physical layer (e/o or wavelength conversion) • Burst switching • Burst assembly problem • Packet switching • Necessity of adaptation the data coming from legacy network to optical packet payload field • Packets disordering problem NOBEL: Berlin May 18-19, 2004

  12. Optical Packet and Optical Burst vsWavelength Switched Model COSTS Hardware (node), building of the network • Wavelength switching • Lower costs then in OBS/OPS case • But very high wavelength consumption • Burst switching • May use cheeper low speed switching elements than in OPS • Costs of advanced optical components • Low wavelength consumption • Packet switching • Very high costs of advanced optical components (FDLs units (for buffering, synchronization), very fast tunable wavelenght converters, very fast switching elements, …) • Costs of high performance electronic control unit • Low wavelength consumption NOBEL: Berlin May 18-19, 2004

  13. Summary Optical Packet and Optical Burst vsWavelength Switched Model NOBEL: Berlin May 18-19, 2004

  14. Nobel-WP3 UPC worksOPS environment • Previous works - studies on contention resolution algorithms for a single switch • UPC contributions in asynchronous, variable length packets scenario • Next step - studies on routing strategies for a network scenario • Adaptive vs. Multipath • Per-packet vs. per-connection • Further works • QoS management taking into account previous results NOBEL: Berlin May 18-19, 2004

  15. Nobel-WP3 UPC worksOBS environment • Previous works • Studies on contention resolution algorithms for a single switch • Burst assembly mechanisms • Signaling protocols • Next step • Studies on the effectiveness of multi-domain contention resolution in a network scenario • Studies on different routing strategies for a networks scenario • Further works • QoS management taking into account the previous results NOBEL: Berlin May 18-19, 2004

  16. Route management • Network models • Packet-switched/wavelength-switched model • Routing models / Route management models • Static routing model(s) [ETH, UPC, all partners] • Combined intra- and inter domain routing model(s) [ETH, UPC] • Adaptive routing model(s) • Predictive routing model(s) • Multicast routing model NOBEL: Berlin May 18-19, 2004

  17. Combined Intra and Inter-Domain routing model • Our Research Focus is on QoS Routing (QoSR) in Optical Networks: • Dynamic Intra-AS QoS light-path provisioning (Optical QoS aware IGP) • Dynamic Inter-AS QoS light-path provisioning (Optical QoS aware EGP) • Coupling between both QoSR mechanisms NOBEL: Berlin May 18-19, 2004

  18. Combined Intra and Inter-Domain routing model • Research Goal: provide a combined Intra and Inter-AS QoS Routing model with the following characteristics: • Highly scalable • Resilience: survivability • Loop-free • Support for different CoS and Policy Control • Clear cut between QoS aware IGP and QoS aware EGP • Per-CoS fast re-route provisioning • Efficiency in terms of the trade-off between the updating frequency, and distributing and maintaining routing state information (inaccuracies) • Suitable signaling for QoS: requirements of the Control Planes for both routing protocols, IGP and EGP NOBEL: Berlin May 18-19, 2004

  19. Combined Intra and Inter-Domain routing model • Line of work: • Survey optical extensions to classical IGPs and EGPs • Development of Metrics and Routing Algorithms for both Intra and Inter-Domain QoS Routing • Efficient coupling between both Routing Algorithms • We also plan to carefully manage how traffic flows so that no starvation of best effort traffic occurs NOBEL: Berlin May 18-19, 2004

  20. Adaptive routing: analyzing the effects of flooding on global network performance • Routing and Wavelength assignment problem (RWA) • Not tractable problem, so divided into: • Routing sub-problem • Wavelength assignment sub-problem • Routing sub-problem • Static routing • Dynamic (adaptive) routing • Static routing: • Fixed-routing • Fixed-alternate routing • Does not consider network dynamics • Dynamic (adaptive) routing: • Adaptive shortest-path routing • Least Congested Path (LCP) • Includes network dynamics in the route selection NOBEL: Berlin May 18-19, 2004

  21. Adaptive routing: analyzing the effects of flooding on global network performance • Dynamic vs static? • Static routing is simpler and not so complex • Dynamic routing is more appropriate for high dynamic networks • Dynamic routing issues: • Route selection must be adapted to network dynamics • Flooding mechanism is required • Mainly for high dynamic networks • Is the network state databases information accurate enough? • Routing inaccuracy problem • Non-suitable path selection because of having inaccurate network state information NOBEL: Berlin May 18-19, 2004

  22. Adaptive routing: analyzing the effects of flooding on global network performance • Flooding mechanism • In an N nodes network, each change results in a N2 messages to be flooded • Leads to instability and scalability • There are not many contributions on optical networks • New techniques must be sought • Approaches could be based on: • Updating by time (hold-down timer) as an IP extension • Updating by number of network state changes • Updating by minimum number of available resources NOBEL: Berlin May 18-19, 2004

  23. Adaptive routing: analyzing the effects of flooding on global network performance • Routing inaccuracy problem: • Routing algorithms must reduce the impact of selecting routes based on inaccurate routing information • New routing algorithms must be sought • Not many contributions in optical networks: • Approaches based on: • Dynamic bypass concept (BBOR): • Rerouting through alternative pre-computed paths • Prediction (PBR): • Route decision according to a “novel” concept of predicted network state information • Simultaneously, flooding is “almost” removed • In short, efforts must be done to develop new adaptive routing mechanisms which include these factors in the route decision NOBEL: Berlin May 18-19, 2004

  24. Prediction Based Routing Usual Routing Algorithms need update messages with information about the network state Network state information is not accurate: - Aggregating information - Triggering of update messages - latency associated in flooded the update messages Routing Algorithms utilise inaccurate state information (RIP) NOBEL: Berlin May 18-19, 2004

  25. Prediction Based Routing • Idea: Source nodes can learn which is the better path and wavelength without update messages • Dynamic learning according to the routing information obtained in previous connections set-up. (Based in branch prediction) • For each wavelength on a path there is a prediction table, PT, to predict the possibility of blocking • For each wavelength on a path there is a history register, WR, with information about if in the last cycles the wavelength on that path has been used NOBEL: Berlin May 18-19, 2004

  26. Prediction Based Routing Index to access PT from wavelength register histories Prediction: Read two-bit counter value < 2 not blocked, value > 1 blocked NOBEL: Berlin May 18-19, 2004

  27. Count PT lambda 0 of SP1 Count PT lambda 1 of SP1 Count PT lambda N-1 of SP1 Count PT lambda 0 of SP2 Count PT lambda N_1 of SP2 ... ... >1 >1 >1 >1 <2 <2 <2 SP1 lambda 0 SP1 lambda 1 SP1 lambda N-1 SP2 lambda 0 SP2 lambda N-1 Prediction Based Routing • Update PT: PT are updated increasing counter if connection request is blocked and decreasing otherwise • Update WR: WR of the wavelength used is updated with 0, and the WR of the unused wavelength are updated with 1 • Prediction Algorithm: Two shortest path, SP1, SP2 and N wavelengths NOBEL: Berlin May 18-19, 2004

  28. Multicast approach in optical transport networks • Main idea: to optimize optical resources utilization • Lightpaths are established point-to-multipoint to overcome the mismatching between optical and client granularities • 1xN Splitters are placed at the optical terminations in order to extend the lightpath to N destinations (N=3 in the example) NOBEL: Berlin May 18-19, 2004

  29. 3 S 1 1 1 2 1 4 1 3 3 5 2 2 1 4 5 Multicast approach in optical transport networks • Example: When a connection from 1 to 3 is requested, the optical channel is transparently extended to nodes 4 and 5 (to allocating future connections from 1 to these nodes) Although resources are wasted firstly, they will be recovered in the future (when new connections from 1 to 4 or 5 arrive). NOBEL: Berlin May 18-19, 2004

  30. Multicast approach in optical transport networks • As it seems difficult to fill a lightpath with traffic generated by a single source to an only destination, the lightpath capacity will be better used if it collects traffic from this source to many destinations. • This will only be true if the granularity difference between lightpath and connections accomplish some constraints. • Some preliminary simulations show that the applied strategy can perform well under certain conditions. NOBEL: Berlin May 18-19, 2004

  31. Multicast approach in optical transport networks • Work Plan: • Start simulations to study the feasibility of the proposed strategy • Study how to physically implement the multicast approach • Find the ratio between granularities and optimal N • To analyze different algorithms to implement the multicast approach • Simulate different traffic patterns NOBEL: Berlin May 18-19, 2004

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