Bug ID 527537: CGNAT experiences increased CPU utilization with a high concurrent connection load and persistence enabled

Last Modified: Aug 19, 2026

Affected Product(s):
BIG-IP CGN(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: Jun 11, 2015

Severity: 3-Major

Symptoms

Elevated CPU with CGNAT when carrying the same load between 11.5 and 11.6

Impact

Elevated CPU = reduced capacity

Conditions

CGNAT lsn-pools high number of concurrent connections persistence = address-port and/or inbound enabled

Workaround

None

Fix Information

Change the sessionDB sweeper to reduce the amount of work it does managing large bins.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips