Bug ID 760050: "cwnd too low" warning message seen in logs

Last Modified: Jul 12, 2023

Affected Product(s):
BIG-IP TMOS(all modules)

Known Affected Versions:
15.1.0, 15.0.0, 14.1.0,,, 12.1.4,, 11.5.9

Fixed In:
16.0.0, 15.1.4,,

Opened: Feb 28, 2019

Severity: 3-Major


The following benign message appears in the log: "cwnd too low." The message can be seen in both tmm logs (where it shows as 'notice' severity) and also in the ltm log (where it shows as 'crit' (critical) severity).


None. TCP resets the congestion window to 1 MSS.


The TCP congestion window has dropped below one Maximum Segment Size, which should not happen.


This message does not indicate a functional issue, so you can safely ignore this message. There is no action to take, but the presence of the message can be useful information for debugging other TCP problems.

Fix Information


Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips