Certain Boolean functions can be generated by irredundant branch-networks, i.e. with networks with only one branch for each variable (literal) of the function. A simple solution (based on graph-theory) is given to the realizability problem for irredundant branch-networks. The theory of irredundant networks is significant for the design of redundant networks, i.e. networks generating functions with a certains protection against temporary branch-errors. A few examples on redundant networks are given and the method of design is compared with methods of coding theory.