In a packet switched communications system having a plurality of switching nodes, each user terminal transmits a packet of data-link layer control protocol including a network-layer control protocol to an adjacent switching node to cause it to be routed to an outgoing transmission link according to the...http://www.google.de/patents/US4799215?utm_source=gb-gplus-sharePatent US4799215 - High-speed packet-switched communications system with end-to-end flow control and retransmission
