Bug ID 514521: Rare TMM Cores with TCP SACK and Early Retransmit

Last Modified: Aug 19, 2026

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

Known Affected Versions:
11.6.0, 11.6.0 hf1, 11.6.0 hf2, 11.6.0 hf3, 11.6.0 hf4, 11.6.0 hf5, 11.6.0 hf6, 11.6.0 hf7, 11.6.0 hf8, 11.6.1, 11.6.1 hf1, 11.6.1 hf2, 11.6.2, 11.6.2 hf1, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 11.6.5.3

Fixed In:
12.0.0

Opened: Mar 26, 2015

Severity: 2-Critical

Related Article: K16417

Symptoms

In certain isolated cases, TCP profiles with Early Retransmit and SACK enabled will cause a TMM Crash.

Impact

Traffic disrupted while tmm restarts.

Conditions

The connection is not in fast recovery but a SACK hole has been retransmitted.

Workaround

Disable Early Retransmit in the TCP profile.

Fix Information

Early retransmit now handles corner cases where the SACK scoreboard is empty.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips