Bug ID 648544: HSB transmitter failure may occur when global COS queues enabled

Last Modified: Oct 16, 2023

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

Known Affected Versions:
11.5.4, 11.5.5, 11.5.6, 11.5.7, 11.5.8, 11.5.9, 11.5.10, 11.6.0, 11.6.1, 11.6.2, 11.6.3,,,,, 11.6.4, 11.6.5,,,, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1

Fixed In:
13.1.0, 12.1.2 HF1

Opened: Mar 01, 2017

Severity: 3-Major

Related Article: K75510491


An HSB transmitter failure may occur if global COS queues enabled. The HSB transmitter failure is logged in the TMM log files.


If this issue occurs then the BIG-IP is rebooted.


With global COS queues enabled, the HSB's watchdog loopback packets are sent on HSB ring 2, instead of ring 0. If HSB ring 2 is heavily utilized, this could cause the loopback packets to be dropped. If this occurs, then the watchdog may trigger an HSB transmitter failure.


Do not use global COS queues.

Fix Information

Loopback packet priority is now set during runtime to guarantee transmit on mgmt ring 0.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips