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WP-JP-S Electro/optic switching architectures Final Review Meeting Turin, 22 April 2008

WP-JP-S Electro/optic switching architectures Final Review Meeting Turin, 22 April 2008. Speaker: Fabio Neri Politecnico di Torino. WP-JP-S : Overview. JP on Electro/optic switching architectures Led by University of Peloponnese, prof. A. Stavdas Advisory Board Andrea Bianco (PoliTo)

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WP-JP-S Electro/optic switching architectures Final Review Meeting Turin, 22 April 2008

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  1. WP-JP-S Electro/optic switching architecturesFinal Review MeetingTurin, 22 April 2008 Speaker: Fabio Neri Politecnico di Torino

  2. WP-JP-S: Overview • JP on Electro/optic switching architectures • Led by University of Peloponnese, prof. A. Stavdas • Advisory Board • Andrea Bianco (PoliTo) • Achille Pattavina (PoliMi) • Carla Raffaelli (DEIS) • Dimitris Syvridis (UoA) • Partners involved • UoPelop • DEIS-UniBO • PoliMI • PoliTO • UoA • UniVi (Collaborating Institution)

  3. Objectives • To assess the merit of all-optical, optoelectronic and electronic switching subsystems and technologies and the synergy between the different technologies for an overall cost effective solution • Study hybrid electro-optical switching architectures. Where appropriate, the corresponding multi-layer node could be comprised by “optically transparent” and “opaque” layers • Technologies and sub-systems for low cost O-E conversion and switching; photonic components as switch elements & fabrics • Migration scenarios from purely electronic switching to optoelectronic towards all-optical • Control complexity assessment of hybrid optoelectronic solutions; switch control complexity vs. network performance (loss, delay, utilization)

  4. Technical approach • In WP7 of e-Photon/ONe (Phase 1), various all-optical and optoelectronic OPXCs were proposed and studied in terms of physical and networking performance; a possible migration scenario from simple/low functionality nodes to high functionality ones was proposed • Despite these advances, it became evident that either some migration steps from a purely electronic world to an all-optical one are still missing, and that all-optical technology is not mature yet, leading to performance degradation (physical and networking) and/or high cost • One of the main and still unresolved issues with OPS and OBS is the contention resolution (applied when packets/bursts compete for the same fiber and wavelength at the same time) • Evaluate hybrid solutions with respect to: • contention resolution schemes (by means of WC, buffering) • switching components (AWGs, microrings) • control and scheduling (synchronous vs. asynchronous, scheduling)

  5. JP-S Organization • Vertical work organization focusing on the quantitative evaluation of the common identified research topics • Collaboration sought to achieve homogenity of contributions

  6. Two paths… • Packet is the new transport and switching granularity. Might be more than one packet size (i.e. L2 frames/bursts/slots) • One approach aiming to explore the IP-router legacy. Optics to merely replace parts of electronic router circuitry. • The other approach is exploring the telecom legacy. Integration of transmission and switching for efficient transportation with network wide (end-to-end) control protocols

  7. 3R regen. Possibly buffering 3R regen. Possibly buffering 3R regen. Possibly buffering Shared resources (WC, buffers) OXC 3R regen. Possibly buffering The global picture l1 lM l1 lM

  8. UoP contributions - Objectives • Contention can also be controlled by means of network-level architectural design, traffic control and network wide control mechanisms • OBS like approaches (control protocols JIT, JET etc.) • UoPelop proposal: CANON • Controlling loss and latency in dynamically reconfigurable architectures is a requirement towards efficient network resource utilization • Objective: investigate the role of switching node architectures in overall network

  9. 1:(N+R) (N+R):1 N:1 Queue Manager 1:N fabric I/F Rx Electronic transparent slot DXC l1 l1 Tx Queue Manager Tx Rx fabric I/F 1 lK lK NxK VOQ UoP contributions - Results • 1st Year Results • Evaluation of a hybrid WDM switch with shared bypass o-e-o switching subsystems • No Wavelength Conversion, no FDLs (simple & effective) • Simulation of hybrid switch in isolation (OPS/OBS paradigm) • 2nd Year Results • Simulation model of optical backbone network based on the hybrid switch node architecture • Control plane protocol is required to coordinate wavelength assignment: • JET-like one-way reservation assumed

  10. . . . … … … PoliTo contributions - Objectives • Analytical assessment of asynchronous vs. synchronous switching performance in input-queued, crossbar-based architectures • Design and performance evaluation of new hybrid electro-optical switches built around a non-blocking optical switching fabric, trying to minimize the use of packet buffering OUT 1 IN 1 . . . . . . OUT N IN N OUT N+1 IN N+1 . . . . . . OUT N+M IN N+M

  11. PoliTo contributions - Results • Switch architectures, built around optical switching fabric, exhibited interesting performance at low complexity • FIFO buffering (FDLs also possible) • Asynchronous operation does not significantly penalize performance (buffering may further improve performance) • Further issues under investigation: • performance in different traffic conditions (e.g., unbalanced destinations, bursty arrivals, different packet sizes) vs. fairness. • complexity of control strategies (eliminate coordination among line-cards)

  12. PoliMi contributions - Objectives • Analysis of OPXCs based on: • All-optical Switching Fabric (SF) based on optical passive Arrayed Waveguide Gratings (AWGs) as alternative to B&S architectures • Electronic Subsystems (ESs) able to perform packet processing and buffering • Input buffering supporting the Virtual Output Queuing (VOQ) mechanism • Performance analysis of the architectures • Comparison of different packet-scheduling algorithms adopted to manage the VOQ system

  13. PoliMi contributions - Results • The use of electronic buffers in the ESs, combined with a suitable wavelength-converter tuning range, greatly enhance the optical-switching fabric performance • Acceptable packet-loss and delay are achievable with limited buffer size • Scheduling algorithms: there is no “absolute winner” – each algorithm has pros and cons • SLIP and LQF are computationally much simpler than MSM (potentially easy hardware implementation) • Best performance in terms of packet-loss rate achieved by LQF • Best performance in terms of packet delay achieved by MSM

  14. M M INPUT 1 INPUT N R 1 L' L L R b 1 λ1 E/O O/E -- λM UniBo contributions - Objectives • N input/output fibers, M wavelengths per fiber • Strictly non-blocking space switching fabric • R Full Range Tunable Wavelength Converters (TWCs) shared per node • Queuing stage with M queues (one per wavelength), with size b • Electronic buffers • FIFO and windowingqueuing policies • Packet loss analysis and switch design to optimize optics and electronics employment

  15. WINDOWING 30 28 26 24 WINDOWING 22 20 1 buffer size 18 16 14 0.9 12 10 Frazione traffico in ottica 8 0.8 6 Ploss=1e-03 4 Ploss=1e-04 0.7 2 Ploss=1e-05 0 0 10 20 30 40 50 60 70 0.6 TWC 0.5 0.4 Ploss=1e-03 0.3 0 10 20 30 40 50 60 70 TWC UniBo contributions - Results • b=f(TWC), to obtain a target PLP • N=16, M=16, L=256, p=0.8 • Different couples (b, TWC) can be chosen to obtain the same packet loss • Switch dimensioning is done by fixing the percentage of traffic that must be forwarded witout O/E/O conversion • # of TWC and buffer size are determined • e.g. PLP = 1e-05

  16. UoA contributions - Objectives Physical Layer Performance issues in OXCs • Novel and cost-effective optical switches based on the nonlinear properties of micro ring resonators

  17. UoA contributions - Results • All-optical switches in micro ring resonators - Wavelength selective switch • A building block of large capacity multifunctional optical cross-connects (OXCs) • Main advantage: The approach combines high capacity integration with low cost fabrication, due to the simple structure of MRs Basic features • It can treat signals with 10Gb/s bitrate • It can provide more than 25dB of ON-OFF contrast ratio • Switching speed less than 1ns • Low power consumption is possible

  18. UniVi contributions - Results • Maximal Size Matching: Parallel Hierarchical Matching (PHM) • Low delay, stability but poor scalability (O(N2)) & number of iterations (O(log2N)). • Load Balanced Birkhoff-von Neumann (LB-BvN): • Scalability (O(1)), O(1) number of iterations, stability but high delay. Proposal: Decoupling PHM • Trade-off between LB-BvN and PHM properties: scalability (O((KL)2) → O(L2), log2(KL) → log2(L)/K number of iterations, stability, delay

  19. Overall assessment of results • Deliverables & Milestones on schedule • Scientific and Technical Impact • Organization & hosting of the International Conference “Photonics in Switching 2006”, held in Crete October 16-18th, 2006. Strong presence of e-photon/ONe+ • A number of papers published in conferences and journals • 7 joint papers published • 9 single papers published • Shared facilities: 5 simulators set up at 5 different partner sites • WP JP-S is characterized by • Strong focus – limited group of participants • Good collaboration • Significant technical contributions & impact

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