Thomas Kunz
Systems and Computer Engineering
371
Congestion Control - Fast retransmit
nFast retransmit
occurs when multiple (>= 3) dupacks come back
nFast
recovery follows fast retransmit
nDifferent from
timeout : slow start follows timeout
–timeout occurs when no more packets are
getting across
–fast retransmit occurs when a packet is lost,
but latter packets get through
–ack clock is still there when fast retransmit
occurs
–no need to slow start