the switch controller swc reserves any packet transfer unit rtb for a certain outgoing route it notifies the rtb that it has been reserved and the outgoing route number through the bus ib during the time in which any packet transfer unit rtb is reserved for a certain outgoing route the switching controller swc upon receipt of a request for connection to the outgoing route from the packet handler ph connects the packet handler ph and the packet transfer unit rtb reserved for that outgoing route so that the packet designated for the outgoing route is transmitted to the transfer unit rtb when a packet is received by the packet receiver pr in the packet transfer unit rtb it is stored in the route packet buffer rpbf in sequence thus when the packet is stored in the packet buffer rpbf the route packet buffer controller rbc requests the switch controller swc through the bus ib to connect itself to the circuit in the desired outgoing route as in the case of the packet handler ph however since there are a plurality of outgoing circuits nc in the packet transfer unit rtb a plurality of connection requests may if necessary be made depending on the number of packets stored in the packet buffer rpbf upon receipt of a connection completion notification from the switch controller swc the packet transfer unit rtb opens the output gate og to transmit the stored packets to the outgoing circuits in sequence when all the packets stored in the packet buffer rpbf have been transmitted and if no new packet is being received the packet transfer unit rtb gives the switch controller swc a packet transmission completion notification the switch controller swc receiving the notification processes any connection.