Bug ID 938309: In-TMM Monitors time out unexpectedly

Last Modified: Sep 16, 2020

Bug Tracker

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

Known Affected Versions:
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, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 13.1.3, 13.1.3.1, 13.1.3.2, 13.1.3.3, 13.1.3.4, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.0.0.5, 14.0.1, 14.0.1.1, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 14.1.2.2, 14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 15.0.0, 15.0.1, 15.0.1.1, 15.0.1.2, 15.0.1.3, 15.0.1.4, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 16.0.0, 16.0.0.1

Opened: Aug 20, 2020
Severity: 3-Major

Symptoms

When using the in-TMM monitoring feature, monitored targets (nodes/pool members) may be marked DOWN unexpectedly if there is a delay in responding to ping attempts. Specifically, if the ping response from the target is delayed by more than the 'interval' value configured for the monitor, but less than the 'timeout' value configured for the monitor, the target may be marked DOWN.

Impact

The monitored target may be marked DOWN if it does not respond to ping attempts within the 'interval' value configured for the monitor, instead of within the 'timeout' value configured for the monitor.

Conditions

This may occur when either: -- In-TMM monitoring is enabled (sys db bigd.tmm = enable) and the monitor type uses in-TMM monitoring; OR -- Bigd is configured to NOT reuse the same socket across consecutive ping attempts (sys db bigd.reusesocket = disable) AND: -- The monitored target does not respond to ping attempts within the 'interval' value configured for the monitor.

Workaround

To work around this issue, use one of the following methods: -- Disable in-TMM monitoring and enable bigd socket reuse (sys db bigd.tmm = disable, and sys db bigd.reusesocket = enable). -- Configure the monitor with an 'interval' value longer than the expected response time for the monitored target(s).

Fix Information

None

Behavior Change