Congestion control in BBN packet-switched networks

We define congestion in a packet network to be the state where performance degrades due to the saturation of a network resource . Resources required by packet networks en compass the communication links between packet switches and the switches' computational resources—processor cycles and buffe r memory . The degradation arises when the network expends resources in doing work i t can't complete . Congestion arises for a number of reasons . The network may simply be underconfigure d for the offered load . Underconfiguration can result from temporary failures elsewhere i n the network, or it may be a busy-hour occurrence, hence not worthy of reconfiguration . In a network whose resources have differen t capacities, when all the capacity of a high speed link is directed over a lower-speed link , that link cannot carry the offered load . Such over-demand can also arise due to the funnel ing together or flows from several incomin g links to an outgoing link . Packet switches should be able to cope gracefully with these situations. They may simply discard the excess packets, relying o n