Scalable Research & Education Networks

1. Scalable Research & Education Networks Dr. Brian Smith, Senior Optical Systems Designer

2. Content • Introduction. • Review of Requirements for Research and Education Regional Optical Networks. • Comparing Strategies for Regional Optical Networks. • Towards seamless overlay of 10Gbps and 40Gbps traffic.

3. Introduction • Regional Optical Networks for Research and Education are being built at an increasing rate • Acquisition of dark fiber – lit up as private networks • Some University focused – some joint education/government initiatives. • Large Scale Research Applications are driving the demand for dedicated bandwidth • Real time image sharing between collaborating institutions • Very Large Baseline Interferometry • Distributed supercomputer simulations • Interactive Video Requires a network that can respond quickly to the demands of the Research Community

4. What features would be required in such a network ? • Dynamic Provisioning • Fully reconfigurable wavelength node • Simple migration from ring to mesh networking. • Ability to switch light-paths using Central/Distributed Management workstation(s). • Single wavelength granularity add and drop. • Seamless switching between DWDM and CWDM providing cost effective multi-grid networks. • Bit rate and protocol transparency – universal interface to higher layers. • Traffic grooming down to ‘STS-1’ level for ultimate flexibility but with GFP for protocol transparency. = Optimum network configuration matched to actual demand.

5. Other Features ? • Simple and Cost-Effective • Transport platform that integrates WDM transmission, wavelength switching and SDH/SONET grooming. • Central or distributed management of all network elements. • Layer 1 performance monitoring at every node – fault isolation. • Auto discovery of nodes, cards and optical interfaces • Interface directly to existing GigE /10GigE routers/switches (carry 10GigE LAN PHY natively without expensive WAN PHY/SONET encapsulation). • Carry any service (Ethernet, SONET, SAN) at wire speed from Fast Ethernet to 10GigE and beyond. Reduced cost and complexity = Rapid response to new Research Initiatives

6. Scalability • Add wavelengths ‘in-service’ with no impact on existing traffic. • Add wavelengths with no adjustments to network provisioning (amplifiers etc). • Seamless overlay of wavelengths carrying traffic up to 2.5G, 10G and 40G over the same fiber. • Allow addition of on-grid alien wavelengths. • Make full use of industry standard technologies such as SFP/XFP to reduce cost and complexity of sparing. All of these features ARE available. . . . .

7. Meriton Product Family Fully Managed via the 8600 NMS & 8300 EMS Metro Access Metro Core & Regional Link Extension Products • 7200 OADX • Multi-transport platform • Wavelength switching (128 l) • STS1 grooming (320G) • CWDM, DWDM & ROADM transmission • Transparent & GFP interfaces • Mesh, ring, star • Scaleable • 1450 OFA Line • Pre/post/line EDFA • Raman Amplifiers • Intelligent controls • Transient suppression • 1510nm OSC • Up to 600 km linkswithout regen • 1100 DCMs • Fully passive with low insertion loss • 3300 OSU • CWDM & DWDM • Transparent & SRM- Ethernet & SANs- STMx, OCx • Ring, star, & linear • 10Gbps supported • Seamless interworking with 7200 OADX

8. OADM vs OADXNetwork Issues

9. Typical OADM Complicates network planning/engineering. - adding a filter affects the whole network. Serial Filter Design Dedicated WDM Transponders Prevents interconnection of CWDM to DWDM. Results in stranded wavelengths around the ring. - all wavelengths in a band are expected to be dropped at the same site Lambda Add/Drop Fixed by Band Adding wavelengths requires service outage. - filter insertion, re-cabling, and power re-balancing. Lack of wavelength switching. - limits networking to point-to-point or ring only. Protection Switching Limited to LOS. Can only switch on hard failures eg. fiber cuts. - Cannot switch on data error rate degradation. Performance Monitoring Limited to Optical Level. Cannot monitor layer 1 (protocol level) error rate. - Cannot detect data errors and degradation. Protocol-specific client-side cards. Truck rolls required to add new service type. - different trib card required per protocol type. Limited Maintenance & Diagnostic Support. Difficult to isolate faults - no electrical loop-backs. Transponder-Based Architecture

10. 7200 OADX –Unique Product Architecture Simplified network design. - Link based design Full 3R Regeneration Wavelength Translation Full CWDM to DWDM connectivity. Non-blocking add/drop of wavelengths. (any wavelength in to any wavelength out). No stranded wavelengths. Wavelength Switching at the Electrical Level Hitless maintenance switches. - of protected lightpaths or cross-connects. Supports up to 16 WDM network interfaces. - allow support of multiple point-to-point, ring, and mesh networks concurrently. Monitoring and detection of layer 1 data errors and degradation. (SONET/SDH, GIGE, FICON, ESCON, Fiber Channel) Performance Monitoring at the Optical and Electrical Level. Protection switching on data error threshold. - protection on loss of signal or error threshold detect Universal client-side cards. Same trib card supports multiple service types. - simplified sparing, pay as you grow upgrade - SFPs Supports Multiple Loopbacks at the Electrical Level. Simplified network troubleshooting. Electronic ROADM Architecture

11. OADM vs OADXMulti-Degree Support West East West East Meriton 7200 OADX Typical OADM 2 WDM Network Interfaces Maximum 16 WDM Network Interfaces Single point-to-point, or single ring network only Multiple point-to-point, multiple ring, multiple mesh network configurations concurrently. Shared network – Not dedicated

12. OADM vs OADXMulti-WDM Interface Support CWDM DWDM CWDM West East CWDM DWDM CWDM DWDM DWDM DWDM West East DWDM CWDM DWDM DWDM DWDM DWDM West East CWDM DWDM DWDM DWDM CWDM CWDM DWDM CWDM CWDM CWDM CWDM DWDM CWDM CWDM DWDM CWDM CWDM OR Meriton 7200 OADX Typical OADM AND AND AND WDM network interfaces must match. Any combination of WDM network interfaces.

13. OADM vs OADX High Error Rate Protection Switching Layer 1 performance monitoring detects high error rate and initiates protection switch. Layer 1 performance monitoring detects high error rate and initiates protection switch. Fiber Kink DWDM CWDM DWDM High error rate initiated protection switching is NOT supported by OADMs. - no level 1 performance monitoring to detect data errors OADX layer 1 performance monitoring is used to detect high error rates and automatically trigger protection switching.

14. OADM vs OADXAdding Wavelengths

15. Typical OADM capacity upgrade 2 L 2L 3L 4L 4 1 3 • OADM solutions address fiber exhaust needs but introduce difficult operational and engineering constraints • Serial Architecture Filter Design (Cascaded & Banded) • Result in Stranded Bandwidth • Serious Scaling Pains w/Re-engineering Required Output w/No Balancing DWDM NE Maximum Power Optical Power l OEO OEO OEO OEO Filter Loss = L

16. 7200 OADX capacity upgrade Mux DWDM band 1 DWDM 1 DWDM 1 DWDM Output w/No Balancing Optical Power l • No power balancing or equalization required when adding wavelengths. • No re-engineering required simply plug in card / SFP / XFP and your up and running

17. Capacity Upgrade – Line Amplifiers 7200 OADX OADM Re-provision optical amplifiers to maintain link-budget 1450 OFA amplifiers use gain control – More Gain – No Pain!

18. OADM vs OADXAdding New Nodes

19. OADM vs OADX – Network Changes Need to add an additional service, including inserting a new POP/node here. “Bridge” the existing service on-the-fly: using existing capacity, point, click, up and running in seconds. “Roll” the existing connection: hitlessly swing the service to the new path, with no service outage. Break the fibre. No service outages! Bring the new Meriton node into service, into the existing network. No service outages! Establish connections to the new equipment. Provision and activate a new light path. “Roll” the existing service back to its original route. Existing operational network and service 7200 OADX bridge-and-roll provides hitless maintenance operations. Bridge and roll is NOT supported by OADMs. - all switch operations result in service disruptions

20. OADM vs OADXMulti-Protocols Trib Card Support SONET OC-12 SONET OC-48 SDH STM-1 SDH STM-4 GigE Meriton 7200 OADX Typical OADM • Single Tributary Interface Card. • Multiple Protocols Require Multiple Cards • Any port – Any Protocol. • More Costly and Complex Upgrades • Universal Pluggable SFP/XFP Interface • More expensive Sparing • Cost Effective Sparing

21. Meriton 7200 OADX vs OADM

22. Overlaying 10G and 40G traffic on existing networks

23. Link Engineering- Challenges 2.5G DWDM 2.5G DWDM DCM OFA 10GOTR Mux DCM OFA DCM OFA 40G Need to understand dispersion tolerance and PMD tolerance to overlay 10G Dispersion tolerance and PMD are much more of an issue when overlaying 40G traffic Lets have a quick look at these issues . . .

24. Dispersion Tolerance Wavelength (nm) Compensation (ps/nm) Dispersion (ps/nmkm) Wavelength (nm) • The dispersion experienced over any km of fiber segment lies within a range defined by the manufacturer. • Similarly, the amount of compensation delivered by a typical DCM is only accurately known within a range.

25. Dispersion Tolerance (cont. .) • Taking a 6 span x 80km link with each span compensated 100%, the actual net dispersion can lie between –500 and +500 ps/nm ! • So how would this large range in net dispersion affect the eye closure penalty for 2.5, 10 and 40G traffic ?

26. 6x80kmx26dB - 32 needs ADCM + enhanced FEC 40G needs FEC 10G 2.5G

27. Polarization Mode Dispersion • Using 6x80kmx26dB with 6 EDFA and 6 DCM, the calculated average DGD (assuming fiber is post 1995) = 2.5 ps • The PMD tolerance (and expected outage) for various data rates is: Rate pmd tolerance system outages/yr 2.5G 30ps insignificant pmd outages/yr 10G 7.6ps insignificant pmd outages/yr 40G(NRZ) 1.9ps ~ 22 minutes/year uncompensated 40G(RZ) 2.7ps ~0.5 seconds/year uncompensated 40G scenarios improved using enhanced FEC and/or PMD compensation.

28. 10G + 40G overlay on existing traffic • With an appropriate adaptive DCM at the receiver and enhanced FEC, 40G traffic can be transmitted over a system designed to support 2.5 and 10G traffic. • With PMD compensation and/or FEC, a 40G(NRZ) system is capable of reaching ~ 500km with no significant outages resulting from PMD. • A 40G(RZ) system with FEC is capable of reaching ~ 700km with no significant outages resulting from PMD

29. Summary • Reviewed some of the requirements for Research and Education Regional Optical Networks. • Compared OADM vs OADX strategies for Regional Optical Networking. • Analyzed the impact of Chromatic Dispersion and PMD tolerance for migration to 40Gbps traffic over existing networks.

30. Thank You Dr. Brian Smith brian.smith@meriton.com