In addition, there are no standardized
protocols for optical layer protection. Although many vendors provide good
solutions, these are proprietary and borrow heavily from SONET/SDH schemes. In
all, these factors give increased OSS integration costs, low interoperability, and impose
complexities for operations staff. By contrast, EoS can extend established carrierclass
OAM coverage to full and fractional-rate EPL/EVPL services via new standards
such as generic framing procedure (GFP), ITU-T G.7041, and link capacity adjustment
scheme (LCAS), ITU-T G.7042 (see Figure 8.8).
Finally, DWDM is a relatively new and highly specialized technology with complex
underlying physical-layer concerns. Hence, most DWDM networks require a sizeable
amount of preplanning design and continual fine-tuning to maintain BER performance.
Some of the key issues here include span loss budgets, amplifier placements, dispersion
compensation, and wavelength assignment. Although third-generation soft-optics DWDM
technologies (see Optical Network Architectures) are helping automate many manual
provisioning tasks, it will still take time and money for carriers to master these technologies.
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