Bug ID 503125: Excessive MPI net traffic can cause tmm panics on chassis systems

Last Modified: Jun 30, 2021

Bug Tracker

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

Known Affected Versions:
11.0.0, 11.1.0, 11.2.0, 11.2.1, 11.3.0, 11.4.0, 11.4.1, 11.5.0, 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, 11.5.4 HF3, 11.5.4 HF4, 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, 12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4

Fixed In:
12.1.0, 11.6.2, 11.5.5

Opened: Jan 27, 2015
Severity: 2-Critical
Related AskF5 Article:


Excessive MPI net traffic can cause tmm panics on chassis systems.


Temporary outage and possible failover when using HA. The source conditions will also continue on the new active device, which can cause repeated failovers. When this occurs, the tmm logs will contain messages similar to: notice MPI stream: connection to node expired for reason: TCP retransmit timeout


This occurs on chassis systems with excessive internal traffic resulting from abnormal load distribution or excessive session DB usage. The session DB usage can be the result of modules or of custom iRules that store session data.


If affected by this when using iRules to create custom keys and data, this can be partially mitigated by consolidating multiple keys and using smaller key lengths as possible. This is affected by the amount of data stored as well, but large keys can exacerbate the issue.

Fix Information

Excessive MPI net traffic no longer causes tmm panics on chassis systems.

Behavior Change