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Nevertheless, fixed OADM rings are generally best-suited for static, long-standing
service profiles, e.g., weeks long or months long holding times. Moreover these setups
mandate careful demand projections, and inaccurate estimates can result in significant
stranded capacity. To mitigate operational complexity, many OADM vendors offer detailed
software planning tools. These packages allow carriers to input their connection demands
and fiber routes/characteristics and then compute the required system configurations at
all nodes, for example, wavelength assignments, VOA settings, amplifier locations, and so
on. Many such tools also provide automated order placement for required modules.
Reconfigurable Add-Drop Rings As traffic dynamics increase, static rings become less
efficient due to excessive preplanning and manual provisioning requirements. Moreover,
larger IOF rings need improved scalability and dynamic on-demand provisioning, particularly
for meshed demands. These contingencies, coupled with advances in ???soft
optics??? switching/tunable technologies, have led to the emergence of third-generation
DWDM systems [3].
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