Bug ID 990173: Dynconfd repeatedly sends the same mcp message to mcpd

Last Modified: Oct 04, 2024

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

Known Affected Versions:
12.1.4.1, 12.1.5, 12.1.5.1, 12.1.5.2, 12.1.5.3, 12.1.6, 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, 13.1.1.2, 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, 13.1.3.5, 13.1.3.6, 13.1.4, 13.1.4.1, 13.1.5, 13.1.5.1, 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, 14.0.1.1, 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, 14.1.2.8, 14.1.3, 14.1.3.1, 14.1.4, 14.1.4.1, 14.1.4.2, 14.1.4.3, 14.1.4.4, 14.1.4.5, 14.1.4.6, 14.1.5, 14.1.5.1, 14.1.5.2, 14.1.5.3, 14.1.5.4, 14.1.5.6, 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, 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, 15.1.10.5, 16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2, 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, 16.1.5, 16.1.5.1

Opened: Feb 03, 2021

Severity: 4-Minor

Symptoms

If dynconfd sends a single message to mcpd containing two or more operations, and one of the operations fails mcpd validation, dynconfd repeatedly sends same message to mcpd. An example of two operations in one mcp message would be an ephemeral node creation and an ephemeral pool member creation in a single mcp message. Once one such message fails, dynconfd repeatedly attempts to resend the same message. In addition, at the next DNS query interval, dynconfd may create one or more new instances of such messages, which may each be retried if they fail. The result can cause an increasing accumulation of MCP messages sent by dynconfd which must be processed by mcpd.

Impact

MCP messages from dynconfd which fail due to an error might cause the population of ephemeral nodes and pool members to fail and become out of sync with what the DNS server is resolving. By repeatedly resending the same messages, which fail repeatedly, dynconfd causes increased mcpd CPU utilization. Eventually, the load caused by processing an increasing accumulation of MCP messages may cause increasing and excessive memory usage by mcpd and a possible mcpd core, or may cause mcpd to become busy and unresponsive and be killed/restarted by SOD.

Conditions

This can occur when: -- Using FQDN nodes and FQDN pool members. -- There is an additional issue where the message from dynconfd fails validation within mcpd (e.g., a misconfiguration in which the monitor assigned to the pool is configured with a wildcard destination and the pool member is added to the pool with a port of '0' or 'any'.

Workaround

Examine the LTM logs for mcpd error messages indicating failed attempts to create ephemeral nodes or ephemeral pool members, and resolve the cause of the failed node or pool-member creation.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips