Note, however, that EoWDM benefits tremendously from
the use of Fast Ethernet thin-mux aggregation blades, without which the cost would spiral
well over EoS. Overall, the declining costs of DWDM technology (20 percent per year)
coupled with increasing gigabit-level demands present very good amortization/payback
periods, for example, range of months to a few years. More importantly, most ROADM
systems feature modularized designs that can grow to accommodate increased channel
counts at moderate costs, providing lower cost-per-bit for higher-volume services.
Carefully note that dark fiber costs are not factored into this study. Instead, it is simply
assumed there are multiple fiber pairs available on the ring. In practice, however, the
lower scalability of EoS will require ???stacking??? multiple TDM rings to match increased
demands, and hence, fiber costs may not be negligible (unless of course EoS is blended
with DWDM transponders). This is of particular relevance to greenfield scenarios.
Solution
Laser
Transponders
(# / Cost)
Thin-mux or
ADM (# / Cost)
AWG Filters
(# / Cost)
WDM EDFA
(# / Cost)
Protection
Modules
(# / Cost)
Total
Cost
EoS (Small) 16 / 128 16 / 128 - / - - / - 8 / 32 288
EoS (Medium) 20 / 196 20 / 160 - / - - / - 8 / 32 388
EoS (Large) 28 / 296 28 / 300 - / - - / - 8 / 32 628
EoWDM (Small) 12 / 48 12 / 48 8 / 64 8 / 32 8 / 32 224
EoWDM (Medium) 16 / 72 16 / 72 8 / 64 8 / 32 8 / 32 272
EoWDM (Large) 20 / 96 20 / 120 8 / 64 8 / 32 8 / 32 344
TABLE 8.
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