Beyond 10 GbE – Looking Ahead Qwest Communications International Mark Stine, CTO Government Services Division February 2005

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 1 Some of the Panel’s Questions What problem are we trying to solve ? How does price/technology/demand determine next step beyond 10 Gbps ? Where are we now ? 40 Gbps/ OC-768 or 100 Gbps ?

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 2 What problem are we trying to solve? For Qwest any new technology must result in: Revenue improvement Enable new services Enable new services Product line consolidation Product line consolidation Increase market coverage; provide services faster Increase market coverage; provide services faster Manage disruption of legacy revenue Manage disruption of legacy revenue Cost reduction Increase utilization Increase utilization Reduce ports; minimize metallic interfaces Reduce ports; minimize metallic interfaces Increase power efficiency and equipment density Increase power efficiency and equipment density Minimize revisits to equipment Minimize revisits to equipment Remote operation Remote operation Operations simplification Convergence, integration of networks Convergence, integration of networks Ease provisioning, network configuration changes Ease provisioning, network configuration changes Improve inventory management Improve inventory management Reduce engineering and planning complexity Reduce engineering and planning complexity Business goals driven by – demand, capital, competition, relationships

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 3 Qwest Multi-service, Packet Centric Infrastructure Broadband Access Broadband Access Pipes Optical, Packet, Wireless Broadband Access Broadband Access Pipes Optical, Packet, Wireless Physical Domain (next gen optical) Physical Domain (next gen optical) OSS Next Generation OSS Control/Applications Domain (distributed intelligence & IP enabled service creation ) Control/Applications Domain (distributed intelligence & IP enabled service creation ) MPLS/IP Domain (switching, aggregation, & Layer 2/3 service intelligence) MPLS/IP Domain (switching, aggregation, & Layer 2/3 service intelligence)

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 4 How does 40 Gbps and 100 Gbps help? More efficient aggregation of traffic Today’s large metro, West coast and East coast routes have sufficient demand to support higher TDM rates beyond 10 Gbps Today’s large metro, West coast and East coast routes have sufficient demand to support higher TDM rates beyond 10 Gbps Traditionally higher TDM rate easier to manage than DWDM Traditionally higher TDM rate easier to manage than DWDM Minimizes or eliminates WDM channels Could be fairly significant in the metro environment as cost avoidance to deploying a metro DWDM system Could be fairly significant in the metro environment as cost avoidance to deploying a metro DWDM system Reduces the number of customer interfaces to manage Cheaper – 40 Gbps getting closer Higher TDM rate interface cards typically prove in at 2.5 times the cost for 4.0 times the bandwidth. For example, 10 Gbps proved in at 2.5 times the cost of 2.5 Gbps Higher TDM rate interface cards typically prove in at 2.5 times the cost for 4.0 times the bandwidth. For example, 10 Gbps proved in at 2.5 times the cost of 2.5 Gbps Solves customer application ???

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 5 Where are we today ? Qwest has demonstrated the largest known 10G/40G BW * D Field Trial Critical achievements: ULH DWDM propagation of Gbps channels at >3000 km with mixed span lengths on Qwest TWC fiber 3x40Gbps and 88x10Gbps propagated over 1516 km 10Gb/s channel 40Gb/s channels 10Gb/s channel System performance met or exceeded all key advertised features and satisfied Qwest requirements - Very good performance as measured by both pre- and post-FEC BER Key caveats System was based mostly upon GA or near GA equipment and results are realizable in real world System was based mostly upon GA or near GA equipment and results are realizable in real world Configuration is not fully optimal and better performance may be achieved Configuration is not fully optimal and better performance may be achieved - PMD not known (probably very low – less than.07ps/sqrt-km) - CD map optimized for 10Gbps (but sufficient for 40Gbps) The results do not include tolerances for best practice engineering (link margins, end-of-life, etc…) The results do not include tolerances for best practice engineering (link margins, end-of-life, etc…)

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 6 40G Trial Configuration:1516km 14 tunable 10Gbps (50 GHz) transponders 3 fixed 40Gbps (100 GHz) transponders 74 CW lasers

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 7 Where are we going? Key Trends in Transport Metro Optical Networking – Large scale EXC/MSPP with optical interfaces Large scale EXC/MSPP with optical interfaces 160Gbps-1.28Tbps capacity 160Gbps-1.28Tbps capacity OC-3c – OC-768(c) OC-3c – OC-768(c) VCAT combined with L2 capabilities VCAT combined with L2 capabilities Metro Optical Ethernet – Carrier grade L2 devices Carrier grade L2 devices Options for MPLS or VLAN traffic management/organization Options for MPLS or VLAN traffic management/organization Ethernet over dark fiber and over DWDM Ethernet over dark fiber and over DWDM Fast-E through 10G LAN PHY Fast-E through 10G LAN PHY Long Haul Optical Transport Expansion of Ethernet in carrier transport space – Ethernet aggregation Expansion of Ethernet in carrier transport space – Ethernet aggregation Agile optical switching (OXCs, ROADMs) Agile optical switching (OXCs, ROADMs) Integrated 10G and 40G DWDM systems Integrated 10G and 40G DWDM systems Tunable and integrated optics Tunable and integrated optics Optical control plane: GMPLS Optical control plane: GMPLS G.709 digital wrappers G.709 digital wrappers Ultra FEC Ultra FEC Raman amplification options Raman amplification options

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 8 Key Disruptive Optical Trends to Watch Optical component consolidation Price disruption may drive optical architectures around these optical components. Price disruption may drive optical architectures around these optical components. Coherent modulation May help enable 40 and 100 Gbps bit rates with lower symbol rates May help enable 40 and 100 Gbps bit rates with lower symbol rates Debate over opaque (digital) and transparent (analog) architectures Depends on the network physical topology, demand set, applications, etc. Depends on the network physical topology, demand set, applications, etc. Some elements of both architectures will be optimal Some elements of both architectures will be optimal

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 9 Optical component consolidation For the last 10 yrs we have been reducing the number of lasers in an optical transport network to reduce cost Ultra Long Haul transponders/modulators, FEC, Raman to improve reach and reduce regeneration Ultra Long Haul transponders/modulators, FEC, Raman to improve reach and reduce regeneration Transparency to reduce through traffic regeneration Transparency to reduce through traffic regeneration What if the costs of lasers and optical components became cheap? Different paradigm. Very disruptive. Consolidation of multiple discrete optical components onto silicon Consolidation of multiple discrete optical components onto silicon Chip yields in full production environment?? Chip yields in full production environment??

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 10 Coherent Modulation - Radio Communications 101 Today’s optical transport equipment uses OOK modulation Some version of NRZ, RZ, & CS-RZ formats Some version of NRZ, RZ, & CS-RZ formats Future coherent modulation is disruptive in the long haul QPSK, PSK, dQPSK, dPSK, QAM, etc QPSK, PSK, dQPSK, dPSK, QAM, etc Offers up to a theoretical gain of 3 dB OSNR over OOK Offers up to a theoretical gain of 3 dB OSNR over OOK More complex receiver design More complex receiver design Appears to be more tolerant to some nonlinear effects, chromatic dispersion and PMD Appears to be more tolerant to some nonlinear effects, chromatic dispersion and PMD

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc. 11 Optical Networking Choices Opaque (Digital) network Transparent (Analog) Network EXC TR SR Passthru Wavelengths EXC Opaque (Digital) Additional grooming points Additional grooming points Simpler design Simpler design More optical signal regeneration on passthru wavelengths More optical signal regeneration on passthru wavelengths Transparent (Analog) Longer reach, More complex modulation and amplification system Longer reach, More complex modulation and amplification system Low cost passthru wavelengths Low cost passthru wavelengths More upfront cost with more all optical components More upfront cost with more all optical components Answer: For Metro and Long Haul Some of both

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc Gbps - Challenges and Answers Fiber PMD on older single mode fiber PMD on older single mode fiber Costs Not quite there Not quite there The technology is in-place and emerging with GA products Qwest has demonstrated in the field that 40 Gbps is viable over real fiber over varying span lengths in the metro and long haul network Good Polarization Mode Dispersion characteristics on TrueWave fiber Likely sweet spot for metro transport as a cost avoidance to DWDM Coherent modulation schemes will improve long haul economics Challenges Answers

Qwest Proprietary and Confidential © 2004 Qwest Communications International Inc Gbps - Challenges and Answers Fiber PMD serious problem on today’s fiber, requires PMD compensators PMD serious problem on today’s fiber, requires PMD compensators Dispersion managed fiber likely required and active dispersion compensators Dispersion managed fiber likely required and active dispersion compensators Component and material limitations Transmitter/Receivers – near electro-optics limits, may require OTDM vs ETDM Transmitter/Receivers – near electro-optics limits, may require OTDM vs ETDM Lasers – very narrow, high repetition pulse rate with low jitter Lasers – very narrow, high repetition pulse rate with low jitter Processors – processing at line rate challenging (limits FEC, for example) Processors – processing at line rate challenging (limits FEC, for example) System concerns Channel spacing fairly wide to avoid FWM Channel spacing fairly wide to avoid FWM OSNR challenged for current long haul amplifier spacing OSNR challenged for current long haul amplifier spacing Nonlinear effects: SPM, XPM Nonlinear effects: SPM, XPM Not yet clear whether 100 Gbps offers net benefits 100 Gbps line rate very tough; may need new fiber for long haul transport Coherent modulation and Inverse Muxing appear most promising  Allows 100 Gbps to be transmitted as multiple 10/20 Gbps signals Challenges Answers

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