Bug ID 597879: CDG Congestion Control can lead to instability

Last Modified: Sep 13, 2023

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

Known Affected Versions:
11.5.1, 11.5.2, 11.5.3, 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, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 11.6.5.3, 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, 12.1.2 HF1, 12.1.2 HF2, 12.1.0, 12.1.1

Fixed In:
13.0.0, 12.1.2

Opened: Jun 07, 2016

Severity: 3-Major

Symptoms

Debug TMM crashes when the TCP congestion window allows an abnormally high or low congestion window. You can see this by looking at the bandwidth value in "tmsh show net cmetrics" if cmetrics-cache is enabled in the TCP profile.

Impact

Traffic disrupted while tmm restarts. In the default TMM, the allowed sending rate will be abnormally high or low.

Conditions

Running the Debug TMM with CDG Congestion Control.

Workaround

Use a congestion control algorithm other than CDG. Switch to the default TMM.

Fix Information

Fixed congestion window calculation in CDG.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips