Bug ID 425250: If datagram lb is enabled with a parking iRule, TMM may crash if more than one response is received

Last Modified: Jul 12, 2023

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

Known Affected Versions:
11.2.0, 11.3.0, 11.4.0, 11.4.1

Fixed In:
11.5.0, 11.4.1 HF9, 11.3.0 HF9

Opened: Jul 15, 2013

Severity: 3-Major

Related Article: K14582


The TMM will segfault. It is difficult to identify this issue without a core analysis.


The TMM will crash and write out a core file. The system should recover on its own. Note, however, that this crash is caused by a specific sequence of events and if those events replay or are mirrored to another device, failover systems may also crash.


* Datagram load-balancing is enabled. * An iRule command which parks is used. Examples include 'delay' and 'table'. * More than one response is received. An example of this situation might be the use of udp dns with the udp_gtm_dns profile (which enabled datagram lb). The DNS_RESPONSE event triggers for each DNS response. If a parking iRule command is used in this event and more than one response is returned from the DNS server, the TMM may crash.


If using datagram load balancing, avoid iRule commands which park in events which may trigger multiple times (e.g. DNS_RESPONSE).

Fix Information

TMM no longer crashes when using iRule parking commands with Datagram Load Balancing. This version silently drops any datagrams received after the first response datagram is egressed to the client.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips