Each IMP monitors the percentage utilization of lines. Associated with this is a real variable u, whose value lies between 0, 0 and 1.0 u is periodically updated using.
unew = auold + (1-a) f
f -> Instance of line utilization . (0 or 1)
a -> constant which determines how fast the IMP 'forgets' recent history.
As 'u' crosses a threshold, the output line enters a 'warning' state. Then a 'Choke Packet' is sent to the source host. When the source host receives the choke packet it is required to reduce the traffic to the destination by X percent. Since some packets have already been sent, the successive choke packets are ignored for some time. Even after that, if choke packets arrive, then the traffic is still reduced.
Two threshold levels can be used. Above the first level the packets are sent and above the second level the packets are discarded. Queue length can also be monitored instead of line utilization.
unew = auold + (1-a) f
f -> Instance of line utilization . (0 or 1)
a -> constant which determines how fast the IMP 'forgets' recent history.
As 'u' crosses a threshold, the output line enters a 'warning' state. Then a 'Choke Packet' is sent to the source host. When the source host receives the choke packet it is required to reduce the traffic to the destination by X percent. Since some packets have already been sent, the successive choke packets are ignored for some time. Even after that, if choke packets arrive, then the traffic is still reduced.
Two threshold levels can be used. Above the first level the packets are sent and above the second level the packets are discarded. Queue length can also be monitored instead of line utilization.
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