Bug ID 502238: Connectivity and traffic interruption issues caused by a stuck HSB transmit ring

Last Modified: Apr 10, 2019

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
11.5.1, 11.5.1 HF1, 11.5.1 HF10, 11.5.1 HF11, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.2, 11.5.2 HF1, 11.5.3, 11.5.3 HF1, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5

Fixed In:
12.0.0, 11.6.0 HF6, 11.5.3 HF2

Opened: Jan 22, 2015
Severity: 3-Major
Related AskF5 Article:
K16736

Symptoms

BIG-IP can experience sudden and permanent traffic interruption, impacting all traffic through TMM.

Impact

The HSB's transmit ring becomes stuck. This requires a TMM restart in order to clear.

Conditions

With TCP Segmentation Offload (TSO) enabled, it is possible to fill up the High-Speed Bridge (HSB) transmit ring, resulting in a stuck transmit ring. The exact conditions under which this occurs is unknown, but it requires sudden transmission of a number of large packets that require TSO in order to result in a full transmit ring.

Workaround

Disable TSO. This can be done using the following steps: 1. tmsh modify sys db tm.tcpsegmentationoffload value disable 2. bigstart restart tmm. If TSO is not disabled, three related fixes are needed to fully address the issue: -- ID 466260, covered in SOL15953: TMM may produce a core file with the 'Assertion we always have room in tx ring! failed' error message. -- ID 502238, covered in SOL16736: The BIG-IP system may lose connectivity and fail to process all traffic through TMM if the HSB is overloaded. -- ID 509782, covered in SOL16780: The BIG-IP system may drop TSO packets. The Solutions are available here: -- https://support.f5.com/kb/en-us/solutions/public/15000/900/sol15953.html -- https://support.f5.com/kb/en-us/solutions/public/16000/700/sol16736.html -- https://support.f5.com/kb/en-us/solutions/public/16000/700/sol16780.html

Fix Information

Three related fixes are needed to fully address the issue: -- ID 466260, covered in SOL15953: TMM may produce a core file with the 'Assertion we always have room in tx ring! failed' error message. -- ID 502238, covered in SOL16736: The BIG-IP system may lose connectivity and fail to process all traffic through TMM if the HSB is overloaded. -- ID 509782, covered in SOL16780: The BIG-IP system may drop TSO packets. The Solutions are available here: -- https://support.f5.com/kb/en-us/solutions/public/15000/900/sol15953.html -- https://support.f5.com/kb/en-us/solutions/public/16000/700/sol16736.html -- https://support.f5.com/kb/en-us/solutions/public/16000/700/sol16780.html

Behavior Change