The impact of nonlinear propagation impairments, amplifier gain ripple, and
inband crosstalk on the performance of an interconnected-ring metropolitan
-scale wavelength-division-multiplexed (WDM) network is investigated. Despi
te the apparently short fiber spans typically encountered in metro networks
, longer paths may arise in interconnected ring architectures. Within these
, nonlinear transmission impairments may become significant even at relativ
ely low launched powers, These paths should be properly engineered to balan
ce the effects of both receiver electrical noise as well as fiber nonlinear
ities. Common-channel crosstalk will also accumulate in typical worst-case
paths introducing additional performance deterioration and as a result cros
stalk level performance requirements need to be set for each elementary com
ponent in the path.