Bug ID 2186009: Increased TX IQ size for netvsc

Last Modified: Dec 19, 2025

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

Known Affected Versions:
17.5.1.3

Opened: Dec 15, 2025

Severity: 3-Major

Symptoms

In some environments, during periods of high traffic, messages could build up in the TX internal queue due to xnet-DPDK being slow to inform that messages were sent. If this goes for long enough, the internal queue will fill up and become stuck.

Impact

Internal queue gets stuck preventing BIG-IP from being able to send messages and causing traffic disruption.

Conditions

1) Using xnet-DPDK driver 2) Azure or Hyper-V 3) Sustained high (multi-GB/s) traffic rate

Workaround

Create '/config/tmm_init.tcl' and add the following line ndal tx_iq_sz 1024 f5f5:f550 Afterwards, restart tmm with 'bigstart restart tmm' to apply change.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips