Bug ID 700405: Disabling TCP segmentation offload can lead to a tmm assert

Last Modified: Jul 12, 2023

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

Known Affected Versions:
13.1.0,,,,,,,,, 13.1.1,,,,, 13.1.3,,,,,,, 13.1.4,, 13.1.5,

Fixed In:

Opened: Jan 02, 2018

Severity: 3-Major


If using vmxnet3 or virtio tmm drivers (not unic), if TCP segmentation offload is disabled while processing traffic, a tmm assert may be observed and tmm will restart. The tmm assert appears similar to the following: notice tso ioctl for member:0 of /Common/internal failed with value: 32tso ioctl for member:0 of /Common/external failed with value: 32panic: ./local/net/packet.h:328: Assertion "packet_ref: not free" failed.


Sometimes tmm will restart, which will lead to traffic group failovers. This is a fairly rare situation, and disabling TCP segmentation offloading is not something routinely done, but if done while under load, this failure might occur.


-- Deploy Virtual Edition (VE) using vmxnet3 or virtio tmm drivers. -- Continuously pass traffic through the system. -- Disable the DB variable tm.tcpsegmentationoffload.


There is no workaround at this time.

Fix Information

This issue no longer occurs.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips