Interconnection topology describes how the processors are connected. All networks consist of switches whose links go to processor-memory nodes and to other switches. There are four generic forms of topology: star, ring, bus, and fully-connected network. Star topology consists of a single hub processor with the other processors directly connected to the single hub, the non-hub processors are not directly connected to each other. In ring topology all processors are on a ring and communication is generally in one direction around the ring. Bus topology is noncyclic, with all nodes connected; consequently, traffic travels in both directions, and some form of arbitration is needed to determine which processor can use the bus at any particular time. In a fully-connected (crossbar) network, every processor has a bidirectional link to every other processor.

Commercially-available parallel processors use multistage network topologies. A multistage network topology is characterized by 2-dimensional grid, and boolean n-cube.