). Although three-dimensional MEMS can support much larger port counts, the postbubble
market has curtailed most development efforts. Hence, only a few vendors offer
all-optical OXC systems today, and future variants will likely use hybrid OXC + DCS
designs. Ring interconnection will likely be the first application of such designs [3].
Optical mesh control frameworks have seen aggressive standardization over the last
decade. Additionally, a wide range of RWA schemes??”centralized and distributed??”have
been developed to provision and recover lightpath connections. Specifically, DWDM
mesh networks can employ both protection and restoration strategies [4]. The former
uses preassigned recovery routes (fiber or lightpath level), whereas the latter uses active,
post-fault signaled recovery (lightpath level). Protection is generally much faster
and offers high availability via dedicated and shared strategies. This enables mesh
networks to support multiple service tiers, akin to SPRING. Meanwhile, restoration
schemes are very wavelength efficient but have slower recovery times (hundreds of
milliseconds).
Coarse WDM (CWDM) Coarse WDM (CWDM) is a form of WDM that is targeted for costsensitive
carriers with smaller metro-edge reach requirements.
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