Bug ID 621379: TCP Lossfilter not enforced after iRule changes TCP settings

Last Modified: Sep 13, 2023

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

Known Affected Versions:
12.1.2, 12.1.3,,,,,, 13.0.0

Fixed In:
13.1.0, 13.0.0 HF1,

Opened: Oct 07, 2016

Severity: 4-Minor


TCP Lossfilter function doesn't work properly, although the first few losses will be properly ignored.


Sending rate declines due to packet losses improperly interpreted as congestion.


TCP profile has ALL of the following settings: mptcp disabled; rate-pace disabled; tail-loss-probe disabled; fast-open disabled; cmetrics-cache-timeout = 0; congestion ctrl is reno, new-reno, high-speed, or scalable; nagle enabled or disabled; rtx_thresh = 3; loss-filter settings are both > 0. an iRule changes any of the above settings except loss-filter.


Change any of the conditions above.

Fix Information

Properly handle loss-filter state when switching TCP stacks.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips