1. 2001 Altamar Networks. All rights reserved Designing US Scale Networks By Paul Tomlinson

2. Overview Transmission technologies –4 technologies Long Reach & Ultra Long Reach With & without Raman –Varying reaches with fibre different types Links –Arbitrary lengths –Arbitrary dB loss Solution test all design possibilities even the use of technology ‘patch works’

3. X Transmission Technology Choice 2,500 km Hypothetical data, do not use out of example context Long Reach (1,000km) Ultra Long Reach (2,000km) Long Reach + Raman (1,500km) Ultra Long Reach + Raman (3,000km) 3R X Good fitGood fit but includes cost of 2 Regens! Regen Required - high cost! Wastage of reach distance & inclusion of 3R costMixture of technologies – Case #1Mixture of technologies – Case #2

4. X Transmission Technology Choice 2,500 km Hypothetical data, do not use out of example context Long Reach (1,000km) Ultra Long Reach (2,000km) Long Reach + Raman (1,500km) Ultra Long Reach + Raman (3,000km) X Cost of transponders Cost of regenerators Cost of Raman amps Number of wavelengths Fibre, floor space, … Which technology gives the least cost fit? Dependencies:

5. Transmission Technology Choice Long Reach (1,000km) Ultra Long Reach (2,000km) Long Reach + Raman (1,500km) Ultra Long Reach + Raman (3,000km) Long Reach only$24m Ultra Long Reach only$27m Long Reach + Raman only$27m Ultra Long Reach + Raman only$15m Ultra Long Reach & Long Reach + Raman$22m Long Reach & Long Reach + Raman$19m Cheapest because no regenerators are required However this can all change with varying distances, number of wavelengths and hardware costs! Hypothetical data, do not use out of example context 2500km link 80km amp spacing Including dispersion compensation 40 Representative costs!

6. Example: least cost transmission technology Link Distance (km) Wavelength Loading LR ULR ULR with Raman LR with Raman Hypothetical data, do not use out of example context The plot shows the least cost technology for varying link distances and wavelength loadings. It varies for different relative component costs.

7. Geography and Topology Constraints Throughout a real network large span distances and poor fiber can reduce dB loss, thus making the minimal cost solution less straight forward x x Node ANode Z Large span distances force the need for regeneration R {{ x x Node ANode Z Or Raman pump over these difficult spans But trade-offs exist! So each possible design must be tested to gain the minimal cost

8. Geography and Topology Constraints Throughout a real network large span distances and poor fiber can reduce dB loss, thus making the minimal cost solution less straight forward x x Node ANode Z OADM’s reduce transparency distances OADM x x Node ANode Z So Raman pump to recover the range But eventually regeneration is needed! So again, each possible design must be tested to gain the minimal cost OADM R

9. Integrated transmission & switching Mux/demux + grooming Service interfaces Patch panel Short reach interfaces Trunk interfaces Mux/demux + grooming Service interfaces Trunk interfaces WDM

10. The following slides were used for the WorldCom presentation – they were based on a generic network design and could be adapted …

11. Value of switch-transport integration 25% capex savings on whole network Up to 46% capex savings on individual nodes –Fewer network elements to manage OC-192 LR/ULR Transponders OC-192 LR/ULR Transponders OC-192 LR/ULR Transponders OC-192 SR Transponders x x Integrated Titanium Stand- Alone Integrated Vs Stand-alone Switch & Transport Stand-Alone Switch + TransportIntegrated Solution Price ($)

12. Value of integrated OADM Fewer transponders & smaller switch matrix reduces capex by further ~13% –Integrated management of pass through channels x OC-192 LR/ULR Transponders all channels Titanium o-e-o x OADM OC-192 LR/ULR Transponders Add-drop channels only Titanium OADM Price Difference with & without OADMs Solution without OADMsSolution with OADMs Price ($) Common Equipment OADMs Optical Shelves Switch Shelves Transponder Shelves

13. Linear scalability Cost scales linearly with growth –All demands were increased by 20% period on period

14. Spares … need more work

15. Challenges in designing transport networks Where should we use OADM’s? Where should we use Raman? What is the best protection type for a given application? How do we trade off transparency with connectivity when applying OADM’s? How can we optimize customer network designs & minimize costs? Where should we groom? How valuable is integration? How scalable is the solution? How can we compare solutions?

16. Generic network How do opaque and transparent networks compare? –Transparent exploits transparency range but analogue performance constrains flexibility –Opaque allows grooming and maximises fill