Bug ID 757827: Allow duplicate FQDN ephemeral create/delete for more reliable FQDN resolution

Last Modified: Oct 16, 2019

Bug Tracker

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

Known Affected Versions:
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, 12.1.5, 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, 13.1.3, 13.1.3.1, 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, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.4, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 15.0.0, 15.0.1

Opened: Feb 06, 2019
Severity: 3-Major

Symptoms

When using FQDN nodes and pool members, ephemeral pool members may not be created as expected immediately after a configuration-load or BIG-IP reboot operation.

Impact

When this issue occurs, some subset of ephemeral pool members may not be created as expected. As a result, some pools may not have any active pool members, and will not pass traffic. This issue, when it occurs, may persist until the next DNS queries occur for each FQDN name, at which point the missing ephemeral pool members are typically created as expected. Using the default fqdn interval value of 3600 seconds, such downtime would last approximately one hour.

Conditions

This may occur on affected BIG-IP versions when: 1. Multiple FQDN names (configured for FQDN nodes/pool members) resolve to the same IP address. 2. DNS queries to resolve these FQDN names occur almost simultaneously. 3. The BIG-IP version in use contains the fix for ID 726319. The occurrence of this issue is very sensitive to timing conditions, and is more likely to occur when there are larger numbers of FQDN names resolving to a common IP address.

Workaround

To minimize the duration of time when pools may be missing ephemeral pool members, configure a shorter fqdn interval value for the FQDN nodes: tmsh mod ltm node fqdn-node-name { fqdn { interval ## } } Where ## is the desired number of seconds between successive DNS queries to resolve the configure FQDN name.

Fix Information

None

Behavior Change