what is the initial snd_ssthresh value

[Haijin Yan <yan@greenhouse.cs.uga.edu>]

Hi,
  What is the initial value of snd_ssthresh for linux 2.4? I guess when 
snd_cwnd grows cross this value, snd_cwnd is governed by cong avoid
algorithm and increases 1 segment every RTT. 

Can anyone clarifies this piece of code?

void tcp_update_metrics(struct sock *sk)
{
      ....
      if (tp->snd_ssthresh >= 0xFFFF) {
      /* Slow start still did not finish. */
      
      }else if (tp->snd_cwnd > tp->snd_ssthresh &&
                 tp->ca_state == TCP_CA_Open) {
      /* Cong. avoidance phase, cwnd is reliable. */
      
        
}

In cong avoidance, snd_cwnd increases at a rate of one seg in a RTT.
so for each ack, does it increase like this:
   tp->snd_cwnd += 1 / tp->snd_cwnd
and snd_cwnd increase 1 only when snd_cwnd acks recieved?
Where the RTT reflects itself here?

Thanks,

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