Symptoms

Any virtual server with UDP profile executing iRule using parking command such as table set. The BIG-IP system drops further UDP packets received on the same connflow while waiting for iRule execution to be completed.

Impact

BIG-IP system drops further UDP packets on the same connflow until iRule execution is completed.

Conditions

This occurs when using iRules containing a parking command in virtual server with UDP profiles. For more information on iRules that suspend processing, see K12962: Some iRule commands temporarily suspend iRule processing at https://support.f5.com/csp/article/K12962

Workaround

Enable datagram-load-balancing in UDP profile associated with the virtual server. This will cause each UDP packet to be treated as a new connflow. This is a valid workaround only if the UDP packets in question can be treated as separate flows (and be load balanced individually).

Fix Information

In 13.0.0, two new parameters have been added to the UDP profile, which can be used to add buffering to UDP flows. Note: The default values create no buffer (buffer-max-packets 0). (tmos)# list ltm profile udp udp all-properties ltm profile udp udp { buffer-max-bytes 655350 buffer-max-packets 0 . . . }

Behavior Change