The Road from 10G to 40G to 100G DWDM Networks www.huawei.com Christopher Skarica Chief Technology Officer North American MSO and Cable Ottawa, Ontario AGENDA WDM Introduction Optical Layer Convergence Dense and Coarse WDM DWDM System Building Blocks DWDM Optical Line Design Considerations Current DWDM Networks and Service Drivers 40G Overview 40G Facts 40G System Design Considerations 40G Deployment Challenges 100G Status 100G Standards Bodies Work and Review (IEEE, ITU, OIF) 100G System Design Considerations 100G Deployment Challenges 40G/100G Components Maturity Review Conclusions Page 2 Definition of WDM W Wavelength D Division M Multiplexing A technology that puts data from different optical sources together, on a single optical fiber, with each signal carried on it’s own separate light wavelength or optical channel Page 3 Easy Integration of WDM Technology with Existing Optical Transport Equipment WDM Fiber Mux 1 SONET Independent Optical Bit Rates and Formats 2 3 4 ATM Gigabit Ethernet Fibre Channel Single Optical Fiber WDM systems integrate easily with existing optical transport equipment and enable access to the untapped capacity of the embedded fiber. They also eliminate the costs associated with mapping common data protocols into traditional networking payloads. Page 4 Convergence at the Optical Layer Traditional Approach Wavelength Networking D1 Video Video Commercial Services IP ESCON SONET SONET OC-1/3/12/48 Fibre Channel Gigabit Ethernet FICON DWDM Optical Network Async •Special Assemblies •Network Overlays •Ubiquitous Networking •Forecast Tolerant One Network = Rapid Services Turn-up & Reduced Operations Costs Page 5 DWDM and CWDM Technology Definitions DWDM – Dense WDM Technology for amplified, high bandwidth applications. Ideal for Metro Core, Regional, and Long Haul applications. Squeezes as many channels as possible into optical spectrum supported by today’s optical amplifier technology. Characterized by a tight channel spacing over a narrow wavelength spectrum, typically 50 – 200 GHz (I.e. 0.4nm – 1.6nm) spacing in the C and L Bands O - Band E - Band 1360 1400 1440 S - Band 1480 1520 C-Band 1560 L - Band 1600 1640 (nm) (nm) 1280 1320 1310 nm DWDM WINDOW CWDM – Coarse WDM Technology for un-amplified, lower channel count applications. Less cost than DWDM. Ideal for Metro Access applications. Characterized by a wide channel spacing over a wide optical spectrum – 20 nm spacing from 1270 – 1610 nm 1310 1290 1330 1270 1350 1370 1390 1410 1430 1450 1470 1490 1510 1530 1550 1570 1590 1610 O - Band E - Band 1360 1400 1440 S - Band 1480 1520 C-Band 1560 L - Band 1600 1640 (nm) (nm)1280 1320 CWDM WINDOW Page 6 EDFA Gain Spectrum O - Band E - Band 1360 1400 1440 S - Band 1480 1520 C-Band 1560 L - Band 1600 1640 (nm) (nm) 1280 1320 1310 nm DWDM WINDOW Operates in 3rd low-loss window of optical fiber near 1.5mm Broad operating range of >30nm Amplification across multiple wavelengths Available for both C-Band and L-Band High optical gain of 20dB to 30dB All-optical amplification Bit-rate insensitive (OC-12, OC-48, OC-192 and beyond) Page 7 Dense WDM Wavelength Plan – ITU-T G.694.1 ITU-T G.694.1 Standard DWDM Channel Assignments 200 GHz spacing = 20 Channels in C Band 100 GHz spacing = 40 Channels in C Band 50 GHz spacing = 80 Channels in C Band 25 GHz spacing = 160 Channels in C Band Standard ITU Grid allows lasers and filters to be built to a common specification Page 8 Optical Network Building Blocks Terminal Line -Translator for Pt. to Pt. connectivity -Translator for Pt. to Pt. connectivity Terminal L2/L3 Switch or SONET Cross Connect L2/L3 Switch or SONET Cross Connect L2/L3 Switch or SONET Cross Connect Line – a DWDM fiber optic system with Optical Amplifiers, dispersion compensation, and optical couplers providing high capacity, pt. to pt., ring, or mesh based connectivity between end points 100’s or 1000’s of km apart Terminal – wavelength translators/combiners for conversion of client optical signals to 1550 nm, DWDM compliant wavelengths AND/OR SONET and L2/L3 switches providing client signal aggregation and presentation of 1550nm, DWDM compliant wavelengths. Page 9 DWDM Building Blocks Software Control ROADM Channel Filter Transponders Group Filter Lambda Granularity Optical Branching Remote Reconfiguration 1 SONET … … Routers Amp Product „x‟ n Channel Filters 200Ghz, 100Ghz, 50Ghz, or 25GHz spacing Amplifiers Low Noise Variable Gain/Flexible Link Budgets Page 10 Optical Line Design Considerations Optical Signal to Noise Ratio performance Dictated by amplifier gain and spacing, no. of channels of system, and OSNR tolerance of DWDM receiver Chromatic and Polarization Mode Dispersion of fiber Different for different bit rate signals Causes Pulse spreading over distance More critical for 10Gbps and higher bit rate signals Non Linear effects that disturb the energy and shape of a signal Caused by high optical power levels, small fiber core diameter, and dispersion characteristic of fiber Page 11 DWDM Optical Line Systems Today The majority of deployed terrestrial DWDM optical line systems have been designed for 40/80 channels (100/50GHz spacing) of 10Gbps signals Amplifier spacing and OSNR performance, dispersion compensation, and NLE avoidance is optimized for 10 Gbps signals in the majority of today‟s networks SO, Why the talk of 40G and 100G and how do we accommodate for these higher rate signals without re-designing the embedded optical line systems ???? Page 12 MSO/Telco Optical Transport Trends National Network Long Haul Optical Networks being deployed/investigated Metro optical primary to reduce the no. of ring transport capacity Internet peering points upgrades and enable long underway….Metro • Network Operation Center distance VOIP transit DWDM Technology is • DWDM Technology • Call Processing Center winning the day Dominating • Data Center • Internet Peering Point Regional Network Regional Headend • Methods of Access network Fiber expansion being ~5km expanded investigated Primary Hub business and residential Secondary Hub service offerings 300-1200Km per span Primary Network 180 ~ 300km circumference DSL HFC PON Secondary Network Page 13 Evolving DWDM Transport Network Digital DWDM Transport Network • Larger Capacity • Flexible • Hub & Mesh Traffic Flows • High Reliability • Efficient Page 14 40G Here Today Commercially deployed and available 40G technology is now standardized in the SDH (STM-256), SONET (OC-768), and OTN (OTU-3) worlds 40G has become commercially deployed (starting in 2007) to increase fiber capacity – many large operators (eg. Verizon, AT&T, Comcast) are running out of wavelengths on existing 10G DWDM line systems 40G DWDM interfaces are about 7-8 X that of a 10G and 10G has been dropping in price more rapidly than 40G BUT, let‟s not confuse this with 40 Gigabit Ethernet which is being ratified and is not an approved standard today !!! (we‟ll talk about that shortly) Page 15 40G Facts Thus far, the largest 40G application has been router-router interconnects (using PoS) with the largest commercial deployments having been Comcast and AT&T Global revenue for 40G line cards in 2007 was $178M – expected to grow 48 percent annually through 2013 and reach almost $2B annually (Ovum) 40 G services expected to grow at a compound annual rate of 59% from 2007-2011 (Infonetics) 40 G is here to stay and will grow dramatically over the coming years How do we accommodate for these higher rate 40G signals without redesigning the embedded optical line systems ? – By using advanced modulation techniques (amplitude and phase – not just 1+0‟s, on and off anymore) to gain spectral efficiencies, coherent receiving, as well as advanced dispersion compensation techniques to make the 40G signal “look” like a 10G signal Page 16 40G Transmission Platform 1*40G SDH/SONET 4*10G SDH/SONET 1*40G SDH/SONET 43Gb/s 43Gb/s 4x10Gb/s 10G, 40G uniform platform 15*22dB @80*40G design rule Router STM-256/OC-768 Router STM-256/OC-768 Page 17 40G is More Nonlinear Sensitive than 10G additional Chirp introduction Reduce Nonlinearity impairment Lower input power under given BER RZ format Differential phase instead of absolute phase 40G is 4 times the frequency of 10G, so inter-channel and intra-channel interferences bring a bigger problem. Long distance transmission systems solve this problem by introducing additional laser chirp, RZ format, differential phase and lower input power Page 18 Technical Challenges from 10G 40G item OSNR Required Filtering effect CD tolerance Challenges: 10G40G 6dB more Solutions Advanced modulation formats 4x more Spectral-efficient modulation format (ODB, xRZ-DQPSK for WDM@50GHz) 1/16 TODC (per channel compensation) Nonlinear effects More sensitive to iFWM & iXPM Nonlinear-resilient RZ format ,chirp processing Multi-level (/multi-carrier) modulation PMD Tolerance 1/4 (DQPSK for reduced symbol rate and better optical spectrum utilization) Advanced Optical Modulation formats and Adaptive per Channel Dispersion Compensation are at the heart of solutions. Page 19 40Gbit/s Modulation summary 40G Formats Channel Space Nonlinear Tolerance Max possible Launch Power (15 spans) OSNR Sensitivity PMD Tolerance ODB CS-RZ NRZ-DPSK PDMQPSK 50GHz Good Ref. Ref. Ref. 100GHz Very Good +3dB +0.5dB 1.5x 100GHz Good +3dB +3dB 1.4x 50GHz Poor -4dB +3dB >6x (6x is 10G’s PMD tolerance) DQPSK 50GHz Good +1dB +3dB 4x Fragmented components supply chain reducing 40G cost reduction ability Page 20 Adaptive Dispersion Compensation Uneven residual dispersion due to unmatched dispersion slopes of DCM and fiber may exceed the dispersion tolerance of a 40G DWDM system ADC (Adaptive Dispersion Compensation) allows DWDM systems to compensate dispersion on per channel basis, and therefore optimize the receiving performance for native 40G over 10G optical line systems 3000 2000 Accumulated Dispersion (ps/nm) annel gth Ch avelen W r e g Lon 1000 0 Short W avelen gth Ch annel -1000 -2000 -3000 0 Terminal's Dispersion Equalization 240 480 720 960 1200 Distance (km) Same receiving performance in 400ps/nm tolerance Page 21 Native 40G over 10G Optimized Optical Line System 10 G Optimized Optical Line System VOA 2.5G OTU DCM DCM DCM DCM 2.5G OTU 10G OTU OADM ADC ADC 10G OTU 40G OTU 40G OTU 40G OTU ADC 40G transceiver unit (OTU) 40G OTU OTM OADM OTM 40G wavelength directly over the existing optimized 10G optical line system： Advanced coding format allows for existing 10G MUX/DMUX Built-in VOA and ADC allows for perfect match with 10G in power level and dispersion High sensitivity receiver (similar power level and OSNR tolerance as for 10G) Same EDFA Transparent transport of client signal 4*10G(OC-192/STM-64) 1*40G(OC-768/STM-256, 10GE WAN/LAN) Page 22 40G/100G Quick Overview The push for 40G and 100G involves BOTH Routing and Transport systems Why the quick jump to 100G from 40G ? – Network traffic growth, router efficiencies and a standards body (IEEE) that decided to work on both 40GbE and 100 GbE at the same time thereby aligning the timetables for both Is this about Cable, Telco‟s – or both ? – Both – mostly driven in North America by Comcast, AT&T, and Verizon What‟s the hype factor – Higher for 100G than 40G The 40G and 100G buzz is coming from both service providers and vendors Page 23 100G Standards Forums IEEE 802.3(40/100GE Interface) Has approved 40G/100G Ethernet Draft Standard-- IEEE802.3ba (In Dec. 2007) Final Ratification Expected in mid 2010 100GE expected to be applied in core networking (Router) and 40GE expected to be applied in servers and computing networking (LAN Switches) Two kinds of 100GE PHY optical client interface were selected: i) 4x25G CWDM for SMF; ii) 10x10G Parallel module for MMF Provide appropriate support for OTN framing (100GE to ODU-4) Proposal for ODU4 Framing It has been accepted in G.709 in Dec.2008; the rate of OTU-4 is 111.809973 Gb/s ITU-T SG15(100G OTN Mapping/Framing) Proposal for 100GE mapping to ODU4 frame: It is under discussion Proposal for OTN evolution: It is under discussion This project will specify a 100G DWDM transmission implementation agreement to include: i) Propagation performance objective ii) Modulation format : Optimized DP-QPSK with a coherent receiver – OFDM also being considered iii) Baseline Forward Error Correction (FEC) algorithm iv) Integrated photonics transmitter/receiver OIF PLL(100G LH Transmission – components/DSP) Page 24 100G – A Developing Standard We Are Here 2007 2008 2009 D J F M 2010 A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N IEEE802.3 100GE Standard IEEE 802.3ba 40GE/100GE PAR Approved IEEE 802.3ba D1.0 TF Draft IEEE 802.3ba D2.0 802.3WG Ballot IEEE 802.3ba D3.0 LMSC Ballot IEEE 802.3ba 40GE/100GE Standard ITU-T Q11/SG15 OTN Standard ODU4 Proposal G.709 Amd3 Consent OTU4 Definition G.709 New Version Consent ITU-T SG15 OTU-4 standard OIF PLL 100G LH Transmission 100G Project Kick off IA Draft IA to Straw Ballot Project Complete IA to Principal Ballot Page 25 From 40G to 100G: Additional Challenges Challenges OSNR Required 10G 40G 6dB more 40G 100G ~4dB more