A CTC-created overhead circuit is missing a cross-connect or network span; a
complete path from source to destination(s) does not exist, or a MAC address changed on one of the circuit nodes and the circuit is in need of repair.
In the CTC, circuits are represented using cross-connects and network spans. If
a network span is missing from a circuit, the circuit status is PARTIAL. However, a PARTIAL status does not necessarily mean a circuit traffic failure has occurred, for traffic might flow on a protect path.