The advent of cyber threats has created a need for a new network planning, design, architecture, operations, control,
situational awareness, management, and maintenance paradigms. Primary considerations include the ability to assess
cyber attack resiliency of the network, and rapidly detect, isolate, and operate during deliberate simultaneous attacks
against the network nodes and links. Legacy network planning relied on automatic protection of a network in the event
of a single fault or a very few simultaneous faults in mesh networks, but in the future it must be augmented to include
improved network resiliency and vulnerability awareness to cyber attacks. Ability to design a resilient network requires
the development of methods to define, and quantify the network resiliency to attacks, and to be able to develop new
optimization strategies for maintaining operations in the midst of these newly emerging cyber threats. Ways to quantify
resiliency, and its use in visualizing cyber vulnerability awareness and in identifying node or link criticality, are
presented in the current work, as well as a methodology of differential network hardening based on the criticality profile
of cyber network components.
Optical coherent techniques are used to eliminate power fading found in optical subcarrier multiplexed systems. In a double-side band optical subcarrier system with direct detection the signal experiences a periodic power fading that is dependent on the fiber dispersion and subcarrier frequency. This power fading results from interference between the two side-bands following the square-law photodetector. It is shown that the use of an appropriately modulated optical local oscillator to coherently detect the subcarrier channel can eliminate this power fading as well as phase error that gives rise to eye distortion. For homodyne detection an optical local oscillator, centered at the optical carrier, is double-sideband suppressed-carrier (DSB-SC) amplitude modulated by the subcarrier frequency of interest. By independently controlling the phases of the optical local oscillator and the DSB-SC modulation both the phase error and power fading of the detected subcarrier channel can be eliminated. This technique also allows the subcarrier to be selected optically, before the optical-to-electrical conversion.
We present a new WADM network node with 50% optical component reduction, 30% smaller footprint, and 35% electrical power saving compared with conventional WADM for optical channel shared protection ring application. It has no single-point-of-failure. Since coherent crosstalk might be a potential issue in this design, we experimentally measured the Q-factor as function of Signal-to-Interference Ratio (SIR) to characterize its performance.