Many solutions have been proposed for fiber-fault monitoring in passive optical networks (PONs) during the last years. Optical coding has attracted particular attention for detecting fiber faults in PONs. These coding modules have particular characteristics that make it suitable for monitoring PON such as inexpensive, passive, and mature devices in their coding settings. In this paper, we investigate and analyze the performance of a set of key optical coding schemes that we have previously introduced for monitoring optical networks. We will derive their key design parameters and evaluate their performance in terms of signal-to-noise ratio, probability of misdetection, and probability of false alarm. We also show how this special category of coding techniques scales up to monitor also various complex architectures of networks. In effect, we extend this to wavelength division multiplexing (WDM) and TDM over WDM-PON. Moreover, we further extend their application to metro ring networks and integrated metropolitan and access networks, referred as long-reach PONs.