We propose Connection then Credits (CTC) as a new end-to-end flow control protocol to handle messagedependent deadlocks in networks-on-chip (NoC) for multicore systems-on-chip. CTC is based on the classic end-toend credit-based flow control protocol but differs from it because it uses a network interface micro-architecture where a single credit counter and a single input data queue are shared among all possible communications. This architectural simplification reduces the area occupation of the network interfaces and increases their design reuse: for instance, the same network interface can be used to connect a core independently of the number of incoming and outgoing communications. CTC, however, requires a handshake preamble to initialize the credit counter in the sender network interface based on the buffering capacity of the receiver network interface. While this necessarily introduces a latency overhead in the transfer of a message, simulationbased experimental results show th...