A switching apparatus includes multiple ports, each including a respective buffer, and a switch controller. The switch controller is configured to concatenate the buffers of at least an input port and an output port selected from among the multiple ports for buffering traffic of a long-haul link, which is connected to the input port and whose delay exceeds buffering capacity of the buffer of the input port alone, and to carry out end-to-end flow control for the long haul link between the output port and the input port.