Bug ID 559522: APM + FPS alerts dropped due to "APM HTTP Body too Big"

Last Modified: Sep 13, 2023

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

Known Affected Versions:
12.1.0, 12.1.1, 12.1.2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5, 12.1.3.6, 12.1.3.7, 12.1.4, 12.1.4.1, 12.1.5, 12.1.5.1, 12.1.5.2, 12.1.5.3, 12.1.6, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 13.1.3, 13.1.3.1, 13.1.3.2, 13.1.3.3, 13.1.3.4, 13.1.3.5, 13.1.3.6, 13.1.4, 13.1.4.1, 13.1.5, 13.1.5.1, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.0.0.5, 14.0.1, 14.0.1.1

Opened: Nov 23, 2015

Severity: 2-Critical

Symptoms

FPS alerts are sent by HTTP POST to a remote server, but if that POST body is too large, APM will reset the connection before the request reaches the remote server. The reset cause will be "APM HTTP Body too Big"

Impact

FPS + APM clientless mode will not work under the default APM configurations.

Conditions

The combination of two conditions results in the dropped request: 1) One of the APM clientless modes is being used 2) The FPS alert request's body must be larger than the configured maximum request body size. The default is 64k

Workaround

The maximum request body size is configurable through a DB variable: setdb tmm.access.maxrequestbodysize 128000

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips