Discussions on Control Plane Architecture
Today’s OTS is a simple “domain of transparency” consisting of WDM Mux/Demuxers and Optical Amplifiers. Because an OTS is not easily reconfigurable today, these constraints are dealt with at the time of installation and don’t complicate routing and the control plane.
As domains of transparency become both larger and software reconfigurable, these physical constraints on connectivity and transmission quality become increasingly of concern to the control plane.
The evolution is largely technology driven => heterogeneous technologies => different in their routing implications.