Finding ways to connect quantum systems in a controlled and flexible fashion lies at the core of constructing quantum information processing systems. Superconducting quantum circuits present a particularly promising platform for engineering quantum systems from the ground up: the strong light-matter interactions in these circuits can readily be used to realize interactions between different components. There remain interesting questions, however, about what types of interactions we can realize. This includes finding means for increasing the degree of connectivity between individual qubits (or qudits), and determine how to dynamically engineer interactions in modular systems. In this talk I will review ongoing efforts to achieve modular scaling using microwave photons as information carriers. I will focus on the use of nonlinear mixing in Josephson junctions to realize microwave photonic interconnects that allow connecting individual qubits and cavities on-demand. Recent experiments in this area have enabled prototypical quantum networks. I will discuss ongoing work that shows the potential for achieving multi-node networks with high degrees of connectivity, and how the tools used in these approaches could be utilized to investigate quantum information protocols in open systems.