Advanced Metering Infrastructures (AMI) are at the base of the Smart Grid concept, as they enable, through a large deployment of metering devices, a distributed, not only energy consumption metering but also a pervasive approach to network monitoring and control. In this work we present and analyze field measurement data provided by a power network manager in order to identify routing anomalies in PLC networks that implement the G3-PLC LOADng routing protocol. In the beginning, we show different types of representations developed in order to easily visualize the network's topology and we give guidelines regarding the semantics for data structures used to describe PLC networks and their topology. We then move onto using the visual tool to incorporate routing data, to facilitate the recognition of patterns and recurring relations; considering also how the topology related to the infrastructure, we observe anomalies in the ways the protocol builds routes from nodes to the Data Concentrator. We eventually discuss how routing and geometrical properties of the topology might be related to each other.
