An island-based integrated circuit includes a configurable mesh data bus. The data bus includes four meshes. Each mesh includes, for each island, a crossbar switch and radiating half links. The half links of adjacent islands align to form links between crossbar switches. A link is implemented as two distributed credit FIFOs. In one direction, a link portion involves a FIFO associated with an output port of a first island, a first chain of registers, and a second FIFO associated with an input port of a second island. When a transaction value passes through the FIFO and through the crossbar switch of the second island, an arbiter in the crossbar switch returns a taken signal. The taken signal passes back through a second chain of registers to a credit count circuit in the first island. The credit count circuit maintains a credit count value for the distributed credit FIFO.