Bug ID 584029: Fragmented packets may cause tmm to core under heavy load

Last Modified: Oct 06, 2020

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.10, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.5.3 HF2, 11.5.4, 11.5.4 HF1, 11.5.4 HF2, 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, 12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2

Fixed In:
13.0.0, 12.1.2 HF1, 11.6.1 HF2, 11.5.4 HF3

Opened: Mar 30, 2016
Severity: 3-Major
Related AskF5 Article:


In rare circumstances, the Traffic Management Microkernel (TMM) process may produce a core file while processing fragmented packets. As a result of this issue, you may encounter one or more of the following symptoms: -- TMM generates a core file in the /shared/core directory. -- In one of the /var/log/tmm log files, you observe an error message similar to the following example: notice panic: ../base/flow_fwd.c:255: Assertion "ffwd flag set" failed. panic: ../net/packet.c:168: Assertion "packet is locked by a driver" failed. notice ** SIGFPE **


The BIG-IP system temporarily fails to process traffic while the TMM process restarts. If the BIG-IP system is configured for high availability (HA), the system fails over to a peer system.


This issue occurs when all of the following conditions are met: -- The TMM process offloads a fragmented packet by way of an ffwd operation. -- Your BIG-IP system is under heavy load.



Fix Information

Fragmented packets no longer cause tmm to core under heavy load.

Behavior Change