A SubnetworkConnection is a logical connection across a subnetwork. A subnetwork is a feature implemented in element managers that allows management of locally connected network elements.
A SubnetworkConnection may pass over several protection groups. It is represented using the relationship LayeredOver a number of LogicalConnections that each represent the connection across a protection group.
If a SubnetworkConnection passes through only one protection group, or it uses linear connection, it is LayeredOver the physical objects directly (TopologicalLinkGroup, or TopologicalLink).
In the case of a singleton subnetwork that passes through only one network element, the SubnetworkConnection has no LayeredOver relationship, but its CTPs are LayeredOver the appropriate PTPs on the network element.