Congestion Action on Loss
TCP has different behaviors, depending on the way it detects loss (RFC2001):
- RTX timer expires:
- ssthresh = MAX(MIN(win,cwnd)/2,2)
- cwnd = 1 (initiates slow-start)
- fast retransmit (fast recovery):
- ssthresh = MAX(MIN(win,cwnd)/2,2)
- cwnd = ssthresh + 3
- each additional dupack increments cwnd by 1
- fast recovery
- (cwnd = ssthresh on new ACK)