Bug ID 1549397: Pool member from statically-configured node deleted along with ephemeral pool member using same IP address

Last Modified: May 29, 2024

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

Known Affected Versions:
15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 15.1.1, 15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5, 16.1.4, 16.1.4.1, 16.1.4.2, 16.1.4.3, 17.0.0, 17.0.0.1, 17.0.0.2, 17.1.0, 17.1.0.1, 17.1.0.2, 17.1.0.3, 17.1.1, 17.1.1.1, 17.1.1.2, 17.1.1.3

Opened: Feb 19, 2024

Severity: 3-Major

Symptoms

If an LTM pool is created containing both FQDN and statically-configured pool members using different port numbers, and the FQDN name resolves to the same IP address as the statically-configured node, if the FQDN name no longer resolves to that IP address, the statically-configured pool member may be deleted along with the ephemeral pool member with the same IP address. In this configuration, the pool in question may be found to contain: -- a statically-configured (not ephemeral) pool member referencing the statically-configured node -- an ephemeral pool member with the same node name and IP address as the statically-configured node Both pool members have the same node name and IP address, since only one node can exist for a given IP address. This prevents a separate ephemeral node from being created with the same IP address as the statically-configured node, forcing both pool members to reference the same statically-configured node with the given IP address.

Impact

Pool members may be deleted unexpectedly when DNS records/name resolution changes.

Conditions

-- The LTM pool contains both FQDN pool members and pool members referencing statically-configured nodes. -- The FQDN and statically-configured pool members use different port numbers. -- The FQDN name resolves to one or more IP addresses that match the statically-configured node. -- The DNS server subsequently no longer resolves the FQDN name to that IP address.

Workaround

To work around this issue: -- Use the same port number for both statically-configured pool members and FQDN pool members. -- Add the statically-configured pool member(s) to the pool before adding any FQDN pool members which resolve to the same IP address(es).

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips