Transcript Congestion Avoidance - TCP Reno and TCP New Reno

Fast
Retransmission
TCP Reno
send missing
packet
≥ 3 dup
ACK’s
≥ 3 dup
ACK’s
cwnd = cwnd + 1
send
packet
cwnd = cwnd +
ACK
Slow
Start
ACK
cwnd ≥ ssthresh
Congestion
Avoidance
send
packet
start FR: cwnd +3
2
1 .
cwnd
Fast
Recovery
dup ACK
cwnd =
cwnd + 1
start
timeout
timeout
non dup ACK
cwnd/2 ( at the start
of the Fast Recovery )
send
packet
start FR
send
packet
timeout
Retransmission
Timeout
TCP New-Reno
Fast
Retransmission
send missing
packet
≥ 3 dup
ACK’s
≥ 3 dup
ACK’s
cwnd = cwnd + 1
send
packet
cwnd = cwnd +
ACK
Slow
Start
start
start FR: cwnd +3
2
send
packet
ACK
cwnd ≥ ssthresh
Congestion
Avoidance
timeout
timeout
1 .
cwnd
send
packet
cwnd = cwnd/2
dup ACK
Fast
Recovery
all packets not ACKed
at the start of the Fast send
Recovery are ACKed
packet
send
packet
timeout
Retransmission
Timeout
cwnd =
cwnd + 1
1st non
dup ACK
cwnd = cwnd
2
send
packet
ACK
cwnd =
cwnd + 1