Аннотация:There are considered networks possessing structure of combined combinatorial block design. The latter are built on the basis of any balanced incomplete combinatorial block design and are distinguished by an explicit representation of both blocks and duality blocks. Considered networks are built on the basis of connecting internal and external subnets, corresponding to blocks and duality blocks of a combinatorial block design. Such systems can be computer networks, key spaces of wireless sensor networks, communication systems and others. The combined representation of blocks and duality blocks is convenient for constructing routing algorithms in such systems, taking into account possible degradation. It is shown that the same combined combinatorial block design can be a model of different systems.