Nesting of the different interface types
We deal with four different kinds of interfaces: physical, bond, bridge and vlan. Some of these are used to construct other interfaces, e.g. two or more physical interfaces are combined into a bond.
The figure on the left shows all the ways in which different interface types can be nested; if we remove VLAN's from the graph, the graph becomes acyclic, which implies that the nesting of interfaces, except for VLAN's, forms a tree.
While the figure indicates there's a loop in using bridges and vlans, in practice, that loop leads to meaningless network configurations.