Bug ID 687044: tcp-half-open monitors might mark a node up in error

Last Modified: May 01, 2019

Bug Tracker

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

Known Affected Versions:
12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2, 12.1.2 HF1, 12.1.2 HF2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5, 12.1.3.6, 12.1.3.7, 12.1.4, 12.1.4.1, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.4

Opened: Oct 04, 2017
Severity: 3-Major

Symptoms

The tcp-half-open monitor might mark a node or pool member up when it is actually down, when multiple transparent monitors within multiple 'bigd' processes probe the same IP-address/port.

Impact

The BIG-IP system might occasionally have an incorrect node or pool-member status, where future probes may fix an incorrect status.

Conditions

All of the following are true: -- There are multiple bigd processes running on the BIG-IP system. -- There are multiple tcp-half-open monitors configured to monitor the same IP address. -- One or more of the monitored objects are up and one or more of the monitored objects are down.

Workaround

You can use any of the following workarounds: -- Configure bigd to run in single process mode by running the following command: tmsh modify sys db bigd.numprocs value 1 -- Use a tcp monitor in place of the tcp-half-open monitor. -- Configure each transparent monitor for different polling cycles to reduce the probability that an 'up' response from the IP address/port is mistakenly viewed as a response to another monitor that is currently 'down'.

Fix Information

None

Behavior Change