Examples relate to switching devices comprising a switch controller and a plurality of interconnected sub-switches forming an internal network of the switching device. A packet is received at a first sub-switch of the plurality of interconnected sub-switches. The packet is to be routed to a particular external output port of a second sub-switch of the plurality of interconnected sub-switches. Upon reception of the packet, the switch controller reserves a space for the packet in a queue associated to the particular external output port. Then, the switch controller routes the packet on the internal network to the particular external output to occupy the reserved space for the packet.