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ITU-T Kaleidoscope 2010 Beyond the Internet? - Innovations for future networks and services

Introducing Elasticity and Adaptation into the Optical Domain Toward More Efficient and Scalable Optical Transport Networks. ITU-T Kaleidoscope 2010 Beyond the Internet? - Innovations for future networks and services. M. Jinno , T. Ohara, Y. Sone, A. Hirano O. Ishida, and M. Tomizawa

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ITU-T Kaleidoscope 2010 Beyond the Internet? - Innovations for future networks and services

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  1. Introducing Elasticity and Adaptation into the Optical Domain Toward More Efficient and Scalable Optical Transport Networks ITU-T Kaleidoscope 2010Beyond the Internet? - Innovations for future networks and services M. Jinno, T. Ohara, Y. Sone, A. Hirano O. Ishida, and M. Tomizawa NTT Network Innovation Labs. (Jinno.masahiko@lab.ntt.co.jp)

  2. Outline • Background: Growing anticipation • SE-conscious optical networking • Early initiatives by ITU-T • Elastic optical path network as a candidate to support future Internet and services • Adoption scenarios from rigid optical networks to elastic optical path network • Possible standardization study items and some solutions relevant to future ITU-T activities

  3. Background (1): Successful Deployment of Optical Networks 100 T 100 Gb/s x 80 (projected) 10 T WDM 40 Gb/s x 40 1 T 10 Gb/s x 80 10 100 G Per fiber capacity (b/s) Spectral efficiency (b/s/Hz) 1 TDM 10 G 0.1 1 G 0.01 100 M 1980 1990 2000 2010 2020 Year of commercialization in Japan • Worldwide intensive R&D activities • Continuous initiative by ITU-T toward OTNs and ASONs • G.709 OTN augmentation to transport 100 GE traffic

  4. Background (2): Slowing Down of SE Improvement BPSK QPSK 1 10 DP-QPSK DP-16QAM Relative optical reach with constant energy per bit (a.u.) Spectral efficiency (b/s/Hz) DP-64QAM 0.1 0.1 DP-256QAM TDM WDM @25 Gbaud DP-1024QAM 0.01 0.01 0 100 200 300 400 500 600 Multi-level mod. Bit rate per channel (Gb/s) PDM Multiplexing technology evolution • Fixed optical amplifier bandwidth (~ 5 THz) • Per fiber capacity increase has been accomplished through boosting SE (bit rate, wavelength, symbol per bit, state of polarization) • Bit loading higher than that for QPSK causes rapid increase in SNR penalty, and results in shorter optical reach • SE improvement for P2P is slowing down, meaning higher rate data need more spectrum Optical amplifier bandwidth (~ 5 THz)

  5. Background (3): Growing Concern of SE in Networking 2008.9 2009.3 2009.9 2010.3 2010.9 2011.3 ECOC2008 “Demonstration of novel spectrum-efficient elastic optical path network ….” (NTT) • Fiber capacity crunch concerns are driving optical networking toward a spectral-efficiency-conscious design philosophy • Right-sized optical bandwidth is adaptively allocated to an end-to-end optical path • Spectral-efficiency-conscious, adaptive networking approach has attracted growing interest • Ex. Elastic optical path network ECOC2009 Symposium “Dynamic multi-layer mesh network” OFC2010 WS “How can we groom and multiplex data for ultra-high-speed transmission” OECC2010 Symposium “Future optical transport network” ECOC2010 Symposium “Towards 1000 Gb/s” OFC2011 WS “Spectrally/bit-rate flexible optical network”

  6. Expected Early ITU-T Initiatives • Early ITU-T initiatives on studying possible extension of OTN and ASON standards are indispensable. • Greatly support rapid advance and adoption of spectrally-efficient and adaptive optical networks • Starting point regarding studying possible extension of OTN and ASON standards in terms of network efficiency • Clarify what should be inherited, what should be extended, and what should be created

  7. Elastic Optical Path Network Path length 1,000 km 1,000 km 1,000 km 250 km 250 km Bit rate 400 Gb/s 400 Gb/s 100 Gb/s 400 Gb/s 100 Gb/s Conventional design Fixed format, grid QPSK 200 Gb/s QPSK QPSK 16QAM 16QAM Adaptive modulation Elastic optical path network Elastic channel spacing • Spectrum-efficient transport of 100 Gb/s services and beyond through introduction of elasticity and adaptation into optical domain • Adaptive spectrum resource allocation according to • Physical conditions on route (path length, node hops) • Actual user traffic volume • SE-conscious adaptive signal modulation • SE-conscious elastic channel spacing

  8. Enabling Hardware Technologies (1)Rate and Reach Flexible Transponder 100 G 100 G~ 400 G 400 G Flexible reach transmitter Flexible rate/reach transmitter • Introduce coherent detection followed by DSP • Optimizing 3 parameters provides required data rate and optical reach while minimizing spectral width • (Symbol rate) x (Number of modulation levels) x （Number of sub-carriers） • Flexible reach • Change the number of bits per symbol with high-speed digital-to-analogue converter and IQ-modulator • Flexible rate • Optical OFDM is spectrally-overlapped orthogonal sub-carrier modulation scheme • Customize number of sub-carriers of OFDM

  9. Enabling Hardware Technologies (2)Bandwidth Agnostic WXC 400 Gb/s 40 Gb/s Trans- mittance Input fiber Output fiber BV WXC 400 Gb/s BV WSS Optical freq. BV WSS 100 Gb/s 40 Gb/s BV WSS BV WSS Spatial light modulator BV WSS BV WSS 100 Gb/s Bandwidth agnostic WXC Grating BV transponder BV transponder Bandwidth variable wavelength selective switch (WSS) • Introduce bandwidth-variable WSS based on, e.g., LCoS • Required minimum spectrum window (optical corridor) is open at every node along optical path • Required width of optical corridor is determined by factoring in signal spectral width and filter clipping effect accumulated along nodes.

  10. Possible Adoption Scenarios Step-by-step Triggered by future higher rate client signals (e.g., 400 Gbps) Earlier adoption To facilitate 100 Gbps ROADM design

  11. Step-by Step Adoption Scenario: Higher Rate Client Triggered (e.g., 400 Gb/s) Equally-spaced Non-ITU-T grid High-SE 400 G accommodation 1 T OTU5 (projected) 400 GE (projected) P2P P2P OTU4 100 GE 100 G OTU3 Elastic channel spacing High-SE multi-rate traffic accommodation STM256 40 GE Bit rate (b/s) OTU2 STM64 10 GE 10 G OTU1 Distance adaptive spectral allocation High-SE multi-reach traffic accommodation GE 1 G Network 1995 2000 2005 2010 2015 2020 Year of standardization Dynamic spectral allocation Optical BoD, highly survivable restoration • Possible next Ethernet rate, 400 G, could appear around 2015. • Optical reach and SE are not independent parameters in 400 G era. • Balancing optical reach and SE in 400 G systems will most likely require elastic spectral allocation

  12. Earlier Adoption Scenario:Large-Scale 100 Gb/s ROADM Design Facilitation 100 GHz grid 100 112 Gb/s DP-QPSK 7 1 12 2 6 75 -45% 11 3 5 112 Gb/s DP-QPSK Required total spectrum at most occupied link (THz) 4 50 100 GHz grid 10 4 112 Gb/s DP-QPSK Allocated spectral width [GHz] 3 Distance adaptive 112Gb/s DP-16QAM 9 5 Distance adaptive 25 2 8 6 1 7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0 Distance–adaptive spectrum allocation Number of node hops Network utilization efficiency Spectrum allocation maps • Even employing DP QPSK modulation, transmitting 100 Gbps signals over multiple hops of ROADMs on a 50 GHz grid is still tough task. • Distance adaptive spectrum allocation will facilitate 100 Gb/s ROADM design for longer paths • Significant spectral-saving when compared with the worst-case design on a 100 GHz grid.

  13. Possible SG15 Study Items OTN • NW Architecture • IF & Mapping Physical Layer • Frequency Grid • Line-IF Application ASON • Protocol Neutral Spec. • Routing & Signaling

  14. OTN Network Architecture OTS OTS OTS OTS OTS OTS OMS OMS OMS Bandwidth agnostic WXC Bandwidth agnostic WXC Tx Tx Rx 3R Mux Demux Mux Demux Mux Demux OCh OCh OTUflex, OTUk-xv OTUflex, OTUk-xv ODUflex, ODUk • G.872 “Architecture of optical transport networks” specifies functional architecture of OTN from network level viewpoint • Layered structure of Optical Channel (OCh), Optical Multiplex Section (OMS), and Optical Transmission Section (OTS) • Although data rate, modulation format, and spectral width of optical path in elastic optical path network may change, elastic optical path is naturally mapped into OCh • See no significant impact on current G.872

  15. OTN Interfaces and Mapping:Current OTN OTU 4 ODU 4 ODU 0 ODU (L) ODU (H) • G.709 “Interfaces for the optical transport network (OTN)” specifies Interfaces and mappings of OTN • Conflicting operator requirements • Transport a wide variety of client signals while minimizing types of line-interfaces in order to reduce capital expenditures, which are dominated by line-interface costs. • LO/HO ODUs and ODUflex can address these conflicting requirements. • LO ODU offers versatility to accommodate various client signals and HO ODU offers simplicity in terms of physical interface. 100 Gb/s OTU 3 ODU 3 OTU 2 10 Gb/s ODU 2 OCh ODUflex (L) OTU 1 ODU 1 1 Gb/s Client signal Map Mux Map E/O OTU OCh ODU

  16. OTN Interfaces and Mapping:Possible Flexible OTU Extension • Rate-flexible OCh enables cost-effective transport of various client signals in fully optical domain w/o electrical multiplexing and grooming • Introduction of rate-flexible OTUs (OTUflex) and rate-flexible HO ODUs (HO ODUflex). Rate-flexible transponder 1 Tb/s ODUflex (L) ODUflex (H) ODUflex OTUflex OTUflex OTU 4 ODU 4 100 Gb/s OCh OTU 3 ODU 3 OTU 2 10 Gb/s ODU 2 OTU 1 Conventional transponder ODU 1 ODU 0 1 Gb/s Client signal Map Mux Map E/O ODU (L) ODU (H) OTU OCh

  17. Physical Layer Specification (1): Possible Frequency Grid Extension f=193.1 THz f=193.2 THz f=193.0 THz n=-1 n=0 n=1 100 GHz 50 GHz 25 GHz 12.5 GHz Frequency grid (G.694.1) -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 Frequency slot (12.5 GHz width) L H L H L H 37.5 GHz 125 GHz 50 GHz Frequency slot allocation • G.694.1 “Spectral grids for WDM applications: DWDM frequency grid” • Anchored to 193.1 THz, and supports various channel spacings of 12.5 GHz, 25 GHz, 50 GHz, and 100 GHz • Explicitly allocate spectral resources to optical path • To quantize continuous spectrum into contiguous frequency slots with appropriate slot width.

  18. Physical Layer Specification (2):Possible Intra-Domain Application Extension TD: Target distance TC: Target capacity BR: Bit rate Recommendation G.696.1Longitudinally compatible intra-domain DWDM applications (TD1, TC1) Capacity Ex. Capacity 40.10G-20L652A(C) (TD2, TC2) (TD, TC) Target distance =20-span, long-haul G.652.A- fiber (C-band) Target Capacity =40 x 10 Gb/s (TD3, TC3) Distance Distance Elastic optical path network Conventional optical network • Conventional systems: • Target distance and capacity are a fixed set of values • Elastic optical path network: • Line interfaces will have multi-reach functionality • Trade-off between optical reach and SE • Variable sets of parameters for target distance and capacity

  19. ASON Control Plane • G. 805, G.7713, G.7714, and G.7715 provide network resource model, requirements, architecture, and protocol neutral specifications for automatically switched optical networks (ASONs), • Based on functional models for SDH (G.803) and OTN (G.872) • No significant impact on current ASON standards when introducing distributed control plane into elastic optical path networks

  20. Possible Technology-Specific Extension of Routing and Signaling PATH message RESV message … Parameters in objects … Label request object Switching type: spectrum switching capable Upstream label object Label object Label: (start slot, end slot) Explicit route object Record route object Modulation format: (symbol rate, no. of sub-carriers, modulation level) Sender TSpec object Flow spec object … … • Need discussion on extension of GMPLS protocols in IETF and OIF with ITU-T SG15 • Define new parameters in signaling messages

  21. Conclusions Elastic optical path network Required minimum spectral resources are adaptively allocated Possible adoption scenarios Study items relevant to future standardization activities of ITU-T SG15 Possible extension of OTN, physical layer, and ASON standards in terms of network efficiency

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