Abstract: Flow of data packets through virtual circuits in a multinode packet switching network is controlled by authorizing packets to enter and to leave each node. When a packet entering a node does not have an authorization (credit) to leave, it is placed in a pool of buffers common to all virtual circuits to await reception of an output credit for the virtual circuit. To avoid buffer congestion, a count is maintained of packets presently stored in and being processed through the node and packets that the node anticipates it will receive. If the count exceeds a predetermined threshold, a packet cannot get an authorization to enter the node unless it has a credit to leave. If the count is below the threshold, credits are granted for packets to enter the node even though there is no authorization to leave.