Impairment Constraints in Transparent Subnetworks
Opaque: each link is optically isolated by expensive transponders doing O/E/O conversions from other links
Transparent: all-optical, bit rate and format independent
- Advantages: cost saving, upgrade flexibility, etc.
- Disadvantage: accumulation of physical impairments
- Not all paths through a transparent subnetwork is feasible in general
Objective: allow expansion of “domain of transparency” with proper routing
=>Need to consider physical impairments including Polarization Mode Dispersion (PMD), Amplifier Spontaneous Emission (ASE), and others