KPI trajectory-driven outlier detection in a network assurance service

In one embodiment, a network assurance service that monitors a network receives a plurality of key performance indicators (KPIs) for a networking device in the network over time. The network assurance service represents relationship changes between the KPIs over time as a set of one or more KPI trajectories. The network assurance service uses a machine learning-based model to determine that a behavior of the networking device is anomalous, based on the one or more KPI trajectories. The network assurance service provides an indication of the anomalous behavior of the networking device to a user interface.