Bug ID 624193: Topology load balancing not working as expected

Last Modified: Apr 28, 2025

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

Known Affected Versions:
11.5.4, 11.5.4 HF1, 11.5.4 HF2, 11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8, 11.6.1, 11.6.1 HF1, 11.6.1 HF2, 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

Fixed In:
13.0.0, 12.1.2 HF1, 11.6.2, 11.5.4 HF3

Opened: Oct 21, 2016

Severity: 3-Major

Related Article: K51651365

Symptoms

Under certain conditions, load balancing decisions can result in an unequal or unexpected distribution.

Impact

The resulting load balancing decisions can lead to an unequal or unexpected distribution of pool selections.

Conditions

Occurs when topology load balancing is used for a wide IP and more than one pool share the highest assigned score for a particular load balancing decision.

Workaround

Topology records and pools can be configured to avoid the conditions which cause the condition.

Fix Information

A system DB variable, gtm.wideiptoporandom, has been added. When this system DB variable is assigned the value of "enable" and more than one pool shares the highest assigned score for a given load balancing decision, a random pool is selected.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips