ltm rule command TCP snd ssthresh

iRule(1)		      BIG-IP TMSH Manual		      iRule(1)



TCP::snd_ssthresh
       Returns the TCP slow start threshold (ssthresh).

SYNOPSIS
       TCP::snd_ssthresh

DESCRIPTION
       The slow start threshold (ssthresh) is the point at which the
       congestion window (cwnd) grows less aggressively. When the cwnd is less
       than ssthresh, it roughly doubles for every cwnd worth of acknowledged
       data. When cwnd is greater than ssthresh, it increases by approximately
       one MSS for each cwnd worth of acknowledged data.

       ssthresh starts at 1,073,725,440 bytes unless there is a cmetrics cache
       entry. When TCP detects packet loss it usually sets ssthresh to a value
       between 1/2 cwnd and cwnd, depending on	connection conditions and the
       congestion control algorithm.

RETURN VALUE
       The connection slow start threshold in bytes.

VALID DURING
       ANY_EVENT

EXAMPLES
	when CLIENT_ACCEPTED {
	    # Get BIGIP's initial slow-start threshold.
	    log local0. "BIGIP's ssthresh: [TCP::snd_ssthresh]"
	}
	when CLIENT_CLOSED {
	    # Get BIGIP's last slow-start threshold.
	    log local0. "BIGIP's ssthresh: [TCP::snd_ssthresh]"
	}

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-12.0.0 --First introduced the command.



BIG-IP				  2017-01-31			      iRule(1)